diff --git a/include/imodule.h b/include/imodule.h
index 9cf0ed05e6..91d9f16258 100644
--- a/include/imodule.h
+++ b/include/imodule.h
@@ -510,5 +510,5 @@ namespace module
 #elif defined(__APPLE__)
     #define DARKRADIANT_DLLEXPORT __attribute__((visibility("default")))
 #else
-    #define DARKRADIANT_DLLEXPORT
+    #define DARKRADIANT_DLLEXPORT __attribute__((visibility("default")))
 #endif
diff --git a/include/iscriptinterface.h b/include/iscriptinterface.h
index 197cef1db0..e66bfc7c0a 100644
--- a/include/iscriptinterface.h
+++ b/include/iscriptinterface.h
@@ -1,6 +1,8 @@
 #pragma once
 
 #include <memory>
+#include <vector>
+#include <utility>
 #include <pybind11/pybind11.h>
 namespace py = pybind11;
 
@@ -10,6 +12,8 @@ namespace script
 class IScriptInterface
 {
 public:
+    using Ptr = std::shared_ptr<IScriptInterface>;
+
     virtual ~IScriptInterface() {}
 
 	/**
@@ -18,6 +22,8 @@ class IScriptInterface
 	*/
 	virtual void registerInterface(py::module& scope, py::dict& globals) = 0;
 };
-typedef std::shared_ptr<IScriptInterface> IScriptInterfacePtr;
+
+using NamedInterface = std::pair<std::string, IScriptInterface::Ptr>;
+using NamedInterfaces = std::vector<NamedInterface>;
 
 }
diff --git a/libs/pybind/pybind11/attr.h b/libs/pybind/pybind11/attr.h
index e38a1a32de..0c41670926 100644
--- a/libs/pybind/pybind11/attr.h
+++ b/libs/pybind/pybind11/attr.h
@@ -1,5 +1,5 @@
 /*
-    pybind11/pybind11.h: Infrastructure for processing custom
+    pybind11/attr.h: Infrastructure for processing custom
     type and function attributes
 
     Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
@@ -12,7 +12,7 @@
 
 #include "cast.h"
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 /// \addtogroup annotations
 /// @{
@@ -23,6 +23,9 @@ struct is_method { handle class_; is_method(const handle &c) : class_(c) { } };
 /// Annotation for operators
 struct is_operator { };
 
+/// Annotation for classes that cannot be subclassed
+struct is_final { };
+
 /// Annotation for parent scope
 struct scope { handle value; scope(const handle &s) : value(s) { } };
 
@@ -37,8 +40,9 @@ struct sibling { handle value; sibling(const handle &value) : value(value.ptr())
 
 /// Annotation indicating that a class derives from another given type
 template <typename T> struct base {
+
     PYBIND11_DEPRECATED("base<T>() was deprecated in favor of specifying 'T' as a template argument to class_")
-    base() { }
+    base() { } // NOLINT(modernize-use-equals-default): breaks MSVC 2015 when adding an attribute
 };
 
 /// Keep patient alive while nurse lives
@@ -58,25 +62,67 @@ struct metaclass {
     handle value;
 
     PYBIND11_DEPRECATED("py::metaclass() is no longer required. It's turned on by default now.")
-    metaclass() = default;
+    metaclass() { } // NOLINT(modernize-use-equals-default): breaks MSVC 2015 when adding an attribute
 
     /// Override pybind11's default metaclass
     explicit metaclass(handle value) : value(value) { }
 };
 
+/// Annotation that marks a class as local to the module:
+struct module_local { const bool value; constexpr module_local(bool v = true) : value(v) { } };
+
 /// Annotation to mark enums as an arithmetic type
 struct arithmetic { };
 
+/// Mark a function for addition at the beginning of the existing overload chain instead of the end
+struct prepend { };
+
+/** \rst
+    A call policy which places one or more guard variables (``Ts...``) around the function call.
+
+    For example, this definition:
+
+    .. code-block:: cpp
+
+        m.def("foo", foo, py::call_guard<T>());
+
+    is equivalent to the following pseudocode:
+
+    .. code-block:: cpp
+
+        m.def("foo", [](args...) {
+            T scope_guard;
+            return foo(args...); // forwarded arguments
+        });
+ \endrst */
+template <typename... Ts> struct call_guard;
+
+template <> struct call_guard<> { using type = detail::void_type; };
+
+template <typename T>
+struct call_guard<T> {
+    static_assert(std::is_default_constructible<T>::value,
+                  "The guard type must be default constructible");
+
+    using type = T;
+};
+
+template <typename T, typename... Ts>
+struct call_guard<T, Ts...> {
+    struct type {
+        T guard{}; // Compose multiple guard types with left-to-right default-constructor order
+        typename call_guard<Ts...>::type next{};
+    };
+};
+
 /// @} annotations
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 /* Forward declarations */
 enum op_id : int;
 enum op_type : int;
 struct undefined_t;
 template <op_id id, op_type ot, typename L = undefined_t, typename R = undefined_t> struct op_;
-template <typename... Args> struct init;
-template <typename... Args> struct init_alias;
 inline void keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret);
 
 /// Internal data structure which holds metadata about a keyword argument
@@ -85,16 +131,18 @@ struct argument_record {
     const char *descr; ///< Human-readable version of the argument value
     handle value;      ///< Associated Python object
     bool convert : 1;  ///< True if the argument is allowed to convert when loading
+    bool none : 1;     ///< True if None is allowed when loading
 
-    argument_record(const char *name, const char *descr, handle value, bool convert)
-        : name(name), descr(descr), value(value), convert(convert) { }
+    argument_record(const char *name, const char *descr, handle value, bool convert, bool none)
+        : name(name), descr(descr), value(value), convert(convert), none(none) { }
 };
 
 /// Internal data structure which holds metadata about a bound function (signature, overloads, etc.)
 struct function_record {
     function_record()
-        : is_constructor(false), is_stateless(false), is_operator(false),
-          has_args(false), has_kwargs(false), is_method(false) { }
+        : is_constructor(false), is_new_style_constructor(false), is_stateless(false),
+          is_operator(false), is_method(false), has_args(false),
+          has_kwargs(false), has_kw_only_args(false), prepend(false) { }
 
     /// Function name
     char *name = nullptr; /* why no C++ strings? They generate heavier code.. */
@@ -123,24 +171,39 @@ struct function_record {
     /// True if name == '__init__'
     bool is_constructor : 1;
 
+    /// True if this is a new-style `__init__` defined in `detail/init.h`
+    bool is_new_style_constructor : 1;
+
     /// True if this is a stateless function pointer
     bool is_stateless : 1;
 
     /// True if this is an operator (__add__), etc.
     bool is_operator : 1;
 
+    /// True if this is a method
+    bool is_method : 1;
+
     /// True if the function has a '*args' argument
     bool has_args : 1;
 
     /// True if the function has a '**kwargs' argument
     bool has_kwargs : 1;
 
-    /// True if this is a method
-    bool is_method : 1;
+    /// True once a 'py::kw_only' is encountered (any following args are keyword-only)
+    bool has_kw_only_args : 1;
+
+    /// True if this function is to be inserted at the beginning of the overload resolution chain
+    bool prepend : 1;
 
     /// Number of arguments (including py::args and/or py::kwargs, if present)
     std::uint16_t nargs;
 
+    /// Number of trailing arguments (counted in `nargs`) that are keyword-only
+    std::uint16_t nargs_kw_only = 0;
+
+    /// Number of leading arguments (counted in `nargs`) that are positional-only
+    std::uint16_t nargs_pos_only = 0;
+
     /// Python method object
     PyMethodDef *def = nullptr;
 
@@ -157,7 +220,8 @@ struct function_record {
 /// Special data structure which (temporarily) holds metadata about a bound class
 struct type_record {
     PYBIND11_NOINLINE type_record()
-        : multiple_inheritance(false), dynamic_attr(false), buffer_protocol(false) { }
+        : multiple_inheritance(false), dynamic_attr(false), buffer_protocol(false),
+          default_holder(true), module_local(false), is_final(false) { }
 
     /// Handle to the parent scope
     handle scope;
@@ -171,17 +235,20 @@ struct type_record {
     /// How large is the underlying C++ type?
     size_t type_size = 0;
 
-    /// How large is pybind11::instance<type>?
-    size_t instance_size = 0;
+    /// What is the alignment of the underlying C++ type?
+    size_t type_align = 0;
+
+    /// How large is the type's holder?
+    size_t holder_size = 0;
 
     /// The global operator new can be overridden with a class-specific variant
-    void *(*operator_new)(size_t) = ::operator new;
+    void *(*operator_new)(size_t) = nullptr;
 
-    /// Function pointer to class_<..>::init_holder
-    void (*init_holder)(PyObject *, const void *) = nullptr;
+    /// Function pointer to class_<..>::init_instance
+    void (*init_instance)(instance *, const void *) = nullptr;
 
     /// Function pointer to class_<..>::dealloc
-    void (*dealloc)(PyObject *) = nullptr;
+    void (*dealloc)(detail::value_and_holder &) = nullptr;
 
     /// List of base classes of the newly created type
     list bases;
@@ -204,17 +271,23 @@ struct type_record {
     /// Is the default (unique_ptr) holder type used?
     bool default_holder : 1;
 
-    PYBIND11_NOINLINE void add_base(const std::type_info *base, void *(*caster)(void *)) {
-        auto base_info = detail::get_type_info(*base, false);
+    /// Is the class definition local to the module shared object?
+    bool module_local : 1;
+
+    /// Is the class inheritable from python classes?
+    bool is_final : 1;
+
+    PYBIND11_NOINLINE void add_base(const std::type_info &base, void *(*caster)(void *)) {
+        auto base_info = detail::get_type_info(base, false);
         if (!base_info) {
-            std::string tname(base->name());
+            std::string tname(base.name());
             detail::clean_type_id(tname);
             pybind11_fail("generic_type: type \"" + std::string(name) +
                           "\" referenced unknown base type \"" + tname + "\"");
         }
 
         if (default_holder != base_info->default_holder) {
-            std::string tname(base->name());
+            std::string tname(base.name());
             detail::clean_type_id(tname);
             pybind11_fail("generic_type: type \"" + std::string(name) + "\" " +
                     (default_holder ? "does not have" : "has") +
@@ -228,16 +301,19 @@ struct type_record {
             dynamic_attr = true;
 
         if (caster)
-            base_info->implicit_casts.push_back(std::make_pair(type, caster));
+            base_info->implicit_casts.emplace_back(type, caster);
     }
 };
 
-inline function_call::function_call(function_record &f, handle p) :
+inline function_call::function_call(const function_record &f, handle p) :
         func(f), parent(p) {
     args.reserve(f.nargs);
     args_convert.reserve(f.nargs);
 }
 
+/// Tag for a new-style `__init__` defined in `detail/init.h`
+struct is_new_style_constructor { };
+
 /**
  * Partial template specializations to process custom attributes provided to
  * cpp_function_ and class_. These are either used to initialize the respective
@@ -296,12 +372,24 @@ template <> struct process_attribute<is_operator> : process_attribute_default<is
     static void init(const is_operator &, function_record *r) { r->is_operator = true; }
 };
 
+template <> struct process_attribute<is_new_style_constructor> : process_attribute_default<is_new_style_constructor> {
+    static void init(const is_new_style_constructor &, function_record *r) { r->is_new_style_constructor = true; }
+};
+
+inline void process_kw_only_arg(const arg &a, function_record *r) {
+    if (!a.name || strlen(a.name) == 0)
+        pybind11_fail("arg(): cannot specify an unnamed argument after an kw_only() annotation");
+    ++r->nargs_kw_only;
+}
+
 /// Process a keyword argument attribute (*without* a default value)
 template <> struct process_attribute<arg> : process_attribute_default<arg> {
     static void init(const arg &a, function_record *r) {
         if (r->is_method && r->args.empty())
-            r->args.emplace_back("self", nullptr, handle(), true /*convert*/);
-        r->args.emplace_back(a.name, nullptr, handle(), !a.flag_noconvert);
+            r->args.emplace_back("self", nullptr, handle(), true /*convert*/, false /*none not allowed*/);
+        r->args.emplace_back(a.name, nullptr, handle(), !a.flag_noconvert, a.flag_none);
+
+        if (r->has_kw_only_args) process_kw_only_arg(a, r);
     }
 };
 
@@ -309,7 +397,7 @@ template <> struct process_attribute<arg> : process_attribute_default<arg> {
 template <> struct process_attribute<arg_v> : process_attribute_default<arg_v> {
     static void init(const arg_v &a, function_record *r) {
         if (r->is_method && r->args.empty())
-            r->args.emplace_back("self", nullptr /*descr*/, handle() /*parent*/, true /*convert*/);
+            r->args.emplace_back("self", nullptr /*descr*/, handle() /*parent*/, true /*convert*/, false /*none not allowed*/);
 
         if (!a.value) {
 #if !defined(NDEBUG)
@@ -332,7 +420,23 @@ template <> struct process_attribute<arg_v> : process_attribute_default<arg_v> {
                           "Compile in debug mode for more information.");
 #endif
         }
-        r->args.emplace_back(a.name, a.descr, a.value.inc_ref(), !a.flag_noconvert);
+        r->args.emplace_back(a.name, a.descr, a.value.inc_ref(), !a.flag_noconvert, a.flag_none);
+
+        if (r->has_kw_only_args) process_kw_only_arg(a, r);
+    }
+};
+
+/// Process a keyword-only-arguments-follow pseudo argument
+template <> struct process_attribute<kw_only> : process_attribute_default<kw_only> {
+    static void init(const kw_only &, function_record *r) {
+        r->has_kw_only_args = true;
+    }
+};
+
+/// Process a positional-only-argument maker
+template <> struct process_attribute<pos_only> : process_attribute_default<pos_only> {
+    static void init(const pos_only &, function_record *r) {
+        r->nargs_pos_only = static_cast<std::uint16_t>(r->args.size());
     }
 };
 
@@ -345,7 +449,7 @@ struct process_attribute<T, enable_if_t<is_pyobject<T>::value>> : process_attrib
 /// Process a parent class attribute (deprecated, does not support multiple inheritance)
 template <typename T>
 struct process_attribute<base<T>> : process_attribute_default<base<T>> {
-    static void init(const base<T> &, type_record *r) { r->add_base(&typeid(T), nullptr); }
+    static void init(const base<T> &, type_record *r) { r->add_base(typeid(T), nullptr); }
 };
 
 /// Process a multiple inheritance attribute
@@ -359,6 +463,11 @@ struct process_attribute<dynamic_attr> : process_attribute_default<dynamic_attr>
     static void init(const dynamic_attr &, type_record *r) { r->dynamic_attr = true; }
 };
 
+template <>
+struct process_attribute<is_final> : process_attribute_default<is_final> {
+    static void init(const is_final &, type_record *r) { r->is_final = true; }
+};
+
 template <>
 struct process_attribute<buffer_protocol> : process_attribute_default<buffer_protocol> {
     static void init(const buffer_protocol &, type_record *r) { r->buffer_protocol = true; }
@@ -369,12 +478,25 @@ struct process_attribute<metaclass> : process_attribute_default<metaclass> {
     static void init(const metaclass &m, type_record *r) { r->metaclass = m.value; }
 };
 
+template <>
+struct process_attribute<module_local> : process_attribute_default<module_local> {
+    static void init(const module_local &l, type_record *r) { r->module_local = l.value; }
+};
+
+/// Process a 'prepend' attribute, putting this at the beginning of the overload chain
+template <>
+struct process_attribute<prepend> : process_attribute_default<prepend> {
+    static void init(const prepend &, function_record *r) { r->prepend = true; }
+};
 
 /// Process an 'arithmetic' attribute for enums (does nothing here)
 template <>
 struct process_attribute<arithmetic> : process_attribute_default<arithmetic> {};
 
-/***
+template <typename... Ts>
+struct process_attribute<call_guard<Ts...>> : process_attribute_default<call_guard<Ts...>> { };
+
+/**
  * Process a keep_alive call policy -- invokes keep_alive_impl during the
  * pre-call handler if both Nurse, Patient != 0 and use the post-call handler
  * otherwise
@@ -410,6 +532,13 @@ template <typename... Args> struct process_attributes {
     }
 };
 
+template <typename T>
+using is_call_guard = is_instantiation<call_guard, T>;
+
+/// Extract the ``type`` from the first `call_guard` in `Extras...` (or `void_type` if none found)
+template <typename... Extra>
+using extract_guard_t = typename exactly_one_t<is_call_guard, call_guard<>, Extra...>::type;
+
 /// Check the number of named arguments at compile time
 template <typename... Extra,
           size_t named = constexpr_sum(std::is_base_of<arg, Extra>::value...),
@@ -418,5 +547,5 @@ constexpr bool expected_num_args(size_t nargs, bool has_args, bool has_kwargs) {
     return named == 0 || (self + named + has_args + has_kwargs) == nargs;
 }
 
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/buffer_info.h b/libs/pybind/pybind11/buffer_info.h
new file mode 100644
index 0000000000..d803004a10
--- /dev/null
+++ b/libs/pybind/pybind11/buffer_info.h
@@ -0,0 +1,146 @@
+/*
+    pybind11/buffer_info.h: Python buffer object interface
+
+    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "detail/common.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+// Default, C-style strides
+inline std::vector<ssize_t> c_strides(const std::vector<ssize_t> &shape, ssize_t itemsize) {
+    auto ndim = shape.size();
+    std::vector<ssize_t> strides(ndim, itemsize);
+    if (ndim > 0)
+        for (size_t i = ndim - 1; i > 0; --i)
+            strides[i - 1] = strides[i] * shape[i];
+    return strides;
+}
+
+// F-style strides; default when constructing an array_t with `ExtraFlags & f_style`
+inline std::vector<ssize_t> f_strides(const std::vector<ssize_t> &shape, ssize_t itemsize) {
+    auto ndim = shape.size();
+    std::vector<ssize_t> strides(ndim, itemsize);
+    for (size_t i = 1; i < ndim; ++i)
+        strides[i] = strides[i - 1] * shape[i - 1];
+    return strides;
+}
+
+PYBIND11_NAMESPACE_END(detail)
+
+/// Information record describing a Python buffer object
+struct buffer_info {
+    void *ptr = nullptr;          // Pointer to the underlying storage
+    ssize_t itemsize = 0;         // Size of individual items in bytes
+    ssize_t size = 0;             // Total number of entries
+    std::string format;           // For homogeneous buffers, this should be set to format_descriptor<T>::format()
+    ssize_t ndim = 0;             // Number of dimensions
+    std::vector<ssize_t> shape;   // Shape of the tensor (1 entry per dimension)
+    std::vector<ssize_t> strides; // Number of bytes between adjacent entries (for each per dimension)
+    bool readonly = false;        // flag to indicate if the underlying storage may be written to
+
+    buffer_info() = default;
+
+    buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
+                detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
+    : ptr(ptr), itemsize(itemsize), size(1), format(format), ndim(ndim),
+      shape(std::move(shape_in)), strides(std::move(strides_in)), readonly(readonly) {
+        if (ndim != (ssize_t) shape.size() || ndim != (ssize_t) strides.size())
+            pybind11_fail("buffer_info: ndim doesn't match shape and/or strides length");
+        for (size_t i = 0; i < (size_t) ndim; ++i)
+            size *= shape[i];
+    }
+
+    template <typename T>
+    buffer_info(T *ptr, detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
+    : buffer_info(private_ctr_tag(), ptr, sizeof(T), format_descriptor<T>::format(), static_cast<ssize_t>(shape_in->size()), std::move(shape_in), std::move(strides_in), readonly) { }
+
+    buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t size, bool readonly=false)
+    : buffer_info(ptr, itemsize, format, 1, {size}, {itemsize}, readonly) { }
+
+    template <typename T>
+    buffer_info(T *ptr, ssize_t size, bool readonly=false)
+    : buffer_info(ptr, sizeof(T), format_descriptor<T>::format(), size, readonly) { }
+
+    template <typename T>
+    buffer_info(const T *ptr, ssize_t size, bool readonly=true)
+    : buffer_info(const_cast<T*>(ptr), sizeof(T), format_descriptor<T>::format(), size, readonly) { }
+
+    explicit buffer_info(Py_buffer *view, bool ownview = true)
+    : buffer_info(view->buf, view->itemsize, view->format, view->ndim,
+            {view->shape, view->shape + view->ndim},
+            /* Though buffer::request() requests PyBUF_STRIDES, ctypes objects
+             * ignore this flag and return a view with NULL strides.
+             * When strides are NULL, build them manually.  */
+            view->strides
+            ? std::vector<ssize_t>(view->strides, view->strides + view->ndim)
+            : detail::c_strides({view->shape, view->shape + view->ndim}, view->itemsize),
+            view->readonly) {
+        this->m_view = view;
+        this->ownview = ownview;
+    }
+
+    buffer_info(const buffer_info &) = delete;
+    buffer_info& operator=(const buffer_info &) = delete;
+
+    buffer_info(buffer_info &&other) {
+        (*this) = std::move(other);
+    }
+
+    buffer_info& operator=(buffer_info &&rhs) {
+        ptr = rhs.ptr;
+        itemsize = rhs.itemsize;
+        size = rhs.size;
+        format = std::move(rhs.format);
+        ndim = rhs.ndim;
+        shape = std::move(rhs.shape);
+        strides = std::move(rhs.strides);
+        std::swap(m_view, rhs.m_view);
+        std::swap(ownview, rhs.ownview);
+        readonly = rhs.readonly;
+        return *this;
+    }
+
+    ~buffer_info() {
+        if (m_view && ownview) { PyBuffer_Release(m_view); delete m_view; }
+    }
+
+    Py_buffer *view() const { return m_view; }
+    Py_buffer *&view() { return m_view; }
+private:
+    struct private_ctr_tag { };
+
+    buffer_info(private_ctr_tag, void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
+                detail::any_container<ssize_t> &&shape_in, detail::any_container<ssize_t> &&strides_in, bool readonly)
+    : buffer_info(ptr, itemsize, format, ndim, std::move(shape_in), std::move(strides_in), readonly) { }
+
+    Py_buffer *m_view = nullptr;
+    bool ownview = false;
+};
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+template <typename T, typename SFINAE = void> struct compare_buffer_info {
+    static bool compare(const buffer_info& b) {
+        return b.format == format_descriptor<T>::format() && b.itemsize == (ssize_t) sizeof(T);
+    }
+};
+
+template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
+    static bool compare(const buffer_info& b) {
+        return (size_t) b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value ||
+            ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) ||
+            ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n")));
+    }
+};
+
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/cast.h b/libs/pybind/pybind11/cast.h
index fe19075e45..11c61a441f 100644
--- a/libs/pybind/pybind11/cast.h
+++ b/libs/pybind/pybind11/cast.h
@@ -11,97 +11,189 @@
 #pragma once
 
 #include "pytypes.h"
-#include "typeid.h"
-#include "descr.h"
+#include "detail/typeid.h"
+#include "detail/descr.h"
+#include "detail/internals.h"
 #include <array>
 #include <limits>
+#include <tuple>
+#include <type_traits>
+
+#if defined(PYBIND11_CPP17)
+#  if defined(__has_include)
+#    if __has_include(<string_view>)
+#      define PYBIND11_HAS_STRING_VIEW
+#    endif
+#  elif defined(_MSC_VER)
+#    define PYBIND11_HAS_STRING_VIEW
+#  endif
+#endif
+#ifdef PYBIND11_HAS_STRING_VIEW
+#include <string_view>
+#endif
+
+#if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
+#  define PYBIND11_HAS_U8STRING
+#endif
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
-inline PyTypeObject *make_static_property_type();
-inline PyTypeObject *make_default_metaclass();
-
-/// Additional type information which does not fit into the PyTypeObject
-struct type_info {
-    PyTypeObject *type;
-    size_t type_size;
-    void *(*operator_new)(size_t);
-    void (*init_holder)(PyObject *, const void *);
-    void (*dealloc)(PyObject *);
-    std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
-    std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;
-    std::vector<bool (*)(PyObject *, void *&)> *direct_conversions;
-    buffer_info *(*get_buffer)(PyObject *, void *) = nullptr;
-    void *get_buffer_data = nullptr;
-    /** A simple type never occurs as a (direct or indirect) parent
-     * of a class that makes use of multiple inheritance */
-    bool simple_type = true;
-    /* for base vs derived holder_type checks */
-    bool default_holder = true;
+/// A life support system for temporary objects created by `type_caster::load()`.
+/// Adding a patient will keep it alive up until the enclosing function returns.
+class loader_life_support {
+public:
+    /// A new patient frame is created when a function is entered
+    loader_life_support() {
+        get_internals().loader_patient_stack.push_back(nullptr);
+    }
+
+    /// ... and destroyed after it returns
+    ~loader_life_support() {
+        auto &stack = get_internals().loader_patient_stack;
+        if (stack.empty())
+            pybind11_fail("loader_life_support: internal error");
+
+        auto ptr = stack.back();
+        stack.pop_back();
+        Py_CLEAR(ptr);
+
+        // A heuristic to reduce the stack's capacity (e.g. after long recursive calls)
+        if (stack.capacity() > 16 && !stack.empty() && stack.capacity() / stack.size() > 2)
+            stack.shrink_to_fit();
+    }
+
+    /// This can only be used inside a pybind11-bound function, either by `argument_loader`
+    /// at argument preparation time or by `py::cast()` at execution time.
+    PYBIND11_NOINLINE static void add_patient(handle h) {
+        auto &stack = get_internals().loader_patient_stack;
+        if (stack.empty())
+            throw cast_error("When called outside a bound function, py::cast() cannot "
+                             "do Python -> C++ conversions which require the creation "
+                             "of temporary values");
+
+        auto &list_ptr = stack.back();
+        if (list_ptr == nullptr) {
+            list_ptr = PyList_New(1);
+            if (!list_ptr)
+                pybind11_fail("loader_life_support: error allocating list");
+            PyList_SET_ITEM(list_ptr, 0, h.inc_ref().ptr());
+        } else {
+            auto result = PyList_Append(list_ptr, h.ptr());
+            if (result == -1)
+                pybind11_fail("loader_life_support: error adding patient");
+        }
+    }
 };
 
-PYBIND11_NOINLINE inline internals &get_internals() {
-    static internals *internals_ptr = nullptr;
-    if (internals_ptr)
-        return *internals_ptr;
-    handle builtins(PyEval_GetBuiltins());
-    const char *id = PYBIND11_INTERNALS_ID;
-    if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
-        internals_ptr = capsule(builtins[id]);
-    } else {
-        internals_ptr = new internals();
-        #if defined(WITH_THREAD)
-            PyEval_InitThreads();
-            PyThreadState *tstate = PyThreadState_Get();
-            internals_ptr->tstate = PyThread_create_key();
-            PyThread_set_key_value(internals_ptr->tstate, tstate);
-            internals_ptr->istate = tstate->interp;
-        #endif
-        builtins[id] = capsule(internals_ptr);
-        internals_ptr->registered_exception_translators.push_front(
-            [](std::exception_ptr p) -> void {
-                try {
-                    if (p) std::rethrow_exception(p);
-                } catch (error_already_set &e)           { e.restore();                                    return;
-                } catch (const builtin_exception &e)     { e.set_error();                                  return;
-                } catch (const std::bad_alloc &e)        { PyErr_SetString(PyExc_MemoryError,   e.what()); return;
-                } catch (const std::domain_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
-                } catch (const std::invalid_argument &e) { PyErr_SetString(PyExc_ValueError,    e.what()); return;
-                } catch (const std::length_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
-                } catch (const std::out_of_range &e)     { PyErr_SetString(PyExc_IndexError,    e.what()); return;
-                } catch (const std::range_error &e)      { PyErr_SetString(PyExc_ValueError,    e.what()); return;
-                } catch (const std::exception &e)        { PyErr_SetString(PyExc_RuntimeError,  e.what()); return;
-                } catch (...) {
-                    PyErr_SetString(PyExc_RuntimeError, "Caught an unknown exception!");
-                    return;
+// Gets the cache entry for the given type, creating it if necessary.  The return value is the pair
+// returned by emplace, i.e. an iterator for the entry and a bool set to `true` if the entry was
+// just created.
+inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_type_info_get_cache(PyTypeObject *type);
+
+// Populates a just-created cache entry.
+PYBIND11_NOINLINE inline void all_type_info_populate(PyTypeObject *t, std::vector<type_info *> &bases) {
+    std::vector<PyTypeObject *> check;
+    for (handle parent : reinterpret_borrow<tuple>(t->tp_bases))
+        check.push_back((PyTypeObject *) parent.ptr());
+
+    auto const &type_dict = get_internals().registered_types_py;
+    for (size_t i = 0; i < check.size(); i++) {
+        auto type = check[i];
+        // Ignore Python2 old-style class super type:
+        if (!PyType_Check((PyObject *) type)) continue;
+
+        // Check `type` in the current set of registered python types:
+        auto it = type_dict.find(type);
+        if (it != type_dict.end()) {
+            // We found a cache entry for it, so it's either pybind-registered or has pre-computed
+            // pybind bases, but we have to make sure we haven't already seen the type(s) before: we
+            // want to follow Python/virtual C++ rules that there should only be one instance of a
+            // common base.
+            for (auto *tinfo : it->second) {
+                // NB: Could use a second set here, rather than doing a linear search, but since
+                // having a large number of immediate pybind11-registered types seems fairly
+                // unlikely, that probably isn't worthwhile.
+                bool found = false;
+                for (auto *known : bases) {
+                    if (known == tinfo) { found = true; break; }
                 }
+                if (!found) bases.push_back(tinfo);
+            }
+        }
+        else if (type->tp_bases) {
+            // It's some python type, so keep follow its bases classes to look for one or more
+            // registered types
+            if (i + 1 == check.size()) {
+                // When we're at the end, we can pop off the current element to avoid growing
+                // `check` when adding just one base (which is typical--i.e. when there is no
+                // multiple inheritance)
+                check.pop_back();
+                i--;
             }
-        );
-        internals_ptr->static_property_type = make_static_property_type();
-        internals_ptr->default_metaclass = make_default_metaclass();
+            for (handle parent : reinterpret_borrow<tuple>(type->tp_bases))
+                check.push_back((PyTypeObject *) parent.ptr());
+        }
     }
-    return *internals_ptr;
 }
 
+/**
+ * Extracts vector of type_info pointers of pybind-registered roots of the given Python type.  Will
+ * be just 1 pybind type for the Python type of a pybind-registered class, or for any Python-side
+ * derived class that uses single inheritance.  Will contain as many types as required for a Python
+ * class that uses multiple inheritance to inherit (directly or indirectly) from multiple
+ * pybind-registered classes.  Will be empty if neither the type nor any base classes are
+ * pybind-registered.
+ *
+ * The value is cached for the lifetime of the Python type.
+ */
+inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type) {
+    auto ins = all_type_info_get_cache(type);
+    if (ins.second)
+        // New cache entry: populate it
+        all_type_info_populate(type, ins.first->second);
+
+    return ins.first->second;
+}
+
+/**
+ * Gets a single pybind11 type info for a python type.  Returns nullptr if neither the type nor any
+ * ancestors are pybind11-registered.  Throws an exception if there are multiple bases--use
+ * `all_type_info` instead if you want to support multiple bases.
+ */
 PYBIND11_NOINLINE inline detail::type_info* get_type_info(PyTypeObject *type) {
-    auto const &type_dict = get_internals().registered_types_py;
-    do {
-        auto it = type_dict.find(type);
-        if (it != type_dict.end())
-            return (detail::type_info *) it->second;
-        type = type->tp_base;
-        if (!type)
-            return nullptr;
-    } while (true);
+    auto &bases = all_type_info(type);
+    if (bases.empty())
+        return nullptr;
+    if (bases.size() > 1)
+        pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
+    return bases.front();
 }
 
-PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_info &tp,
-                                                          bool throw_if_missing = false) {
-    auto &types = get_internals().registered_types_cpp;
+inline detail::type_info *get_local_type_info(const std::type_index &tp) {
+    auto &locals = registered_local_types_cpp();
+    auto it = locals.find(tp);
+    if (it != locals.end())
+        return it->second;
+    return nullptr;
+}
 
-    auto it = types.find(std::type_index(tp));
+inline detail::type_info *get_global_type_info(const std::type_index &tp) {
+    auto &types = get_internals().registered_types_cpp;
+    auto it = types.find(tp);
     if (it != types.end())
-        return (detail::type_info *) it->second;
+        return it->second;
+    return nullptr;
+}
+
+/// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr.
+PYBIND11_NOINLINE inline detail::type_info *get_type_info(const std::type_index &tp,
+                                                          bool throw_if_missing = false) {
+    if (auto ltype = get_local_type_info(tp))
+        return ltype;
+    if (auto gtype = get_global_type_info(tp))
+        return gtype;
+
     if (throw_if_missing) {
         std::string tname = tp.name();
         detail::clean_type_id(tname);
@@ -115,6 +207,199 @@ PYBIND11_NOINLINE inline handle get_type_handle(const std::type_info &tp, bool t
     return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
 }
 
+struct value_and_holder {
+    instance *inst = nullptr;
+    size_t index = 0u;
+    const detail::type_info *type = nullptr;
+    void **vh = nullptr;
+
+    // Main constructor for a found value/holder:
+    value_and_holder(instance *i, const detail::type_info *type, size_t vpos, size_t index) :
+        inst{i}, index{index}, type{type},
+        vh{inst->simple_layout ? inst->simple_value_holder : &inst->nonsimple.values_and_holders[vpos]}
+    {}
+
+    // Default constructor (used to signal a value-and-holder not found by get_value_and_holder())
+    value_and_holder() = default;
+
+    // Used for past-the-end iterator
+    value_and_holder(size_t index) : index{index} {}
+
+    template <typename V = void> V *&value_ptr() const {
+        return reinterpret_cast<V *&>(vh[0]);
+    }
+    // True if this `value_and_holder` has a non-null value pointer
+    explicit operator bool() const { return value_ptr(); }
+
+    template <typename H> H &holder() const {
+        return reinterpret_cast<H &>(vh[1]);
+    }
+    bool holder_constructed() const {
+        return inst->simple_layout
+            ? inst->simple_holder_constructed
+            : inst->nonsimple.status[index] & instance::status_holder_constructed;
+    }
+    void set_holder_constructed(bool v = true) {
+        if (inst->simple_layout)
+            inst->simple_holder_constructed = v;
+        else if (v)
+            inst->nonsimple.status[index] |= instance::status_holder_constructed;
+        else
+            inst->nonsimple.status[index] &= (uint8_t) ~instance::status_holder_constructed;
+    }
+    bool instance_registered() const {
+        return inst->simple_layout
+            ? inst->simple_instance_registered
+            : inst->nonsimple.status[index] & instance::status_instance_registered;
+    }
+    void set_instance_registered(bool v = true) {
+        if (inst->simple_layout)
+            inst->simple_instance_registered = v;
+        else if (v)
+            inst->nonsimple.status[index] |= instance::status_instance_registered;
+        else
+            inst->nonsimple.status[index] &= (uint8_t) ~instance::status_instance_registered;
+    }
+};
+
+// Container for accessing and iterating over an instance's values/holders
+struct values_and_holders {
+private:
+    instance *inst;
+    using type_vec = std::vector<detail::type_info *>;
+    const type_vec &tinfo;
+
+public:
+    values_and_holders(instance *inst) : inst{inst}, tinfo(all_type_info(Py_TYPE(inst))) {}
+
+    struct iterator {
+    private:
+        instance *inst = nullptr;
+        const type_vec *types = nullptr;
+        value_and_holder curr;
+        friend struct values_and_holders;
+        iterator(instance *inst, const type_vec *tinfo)
+            : inst{inst}, types{tinfo},
+            curr(inst /* instance */,
+                 types->empty() ? nullptr : (*types)[0] /* type info */,
+                 0, /* vpos: (non-simple types only): the first vptr comes first */
+                 0 /* index */)
+        {}
+        // Past-the-end iterator:
+        iterator(size_t end) : curr(end) {}
+    public:
+        bool operator==(const iterator &other) const { return curr.index == other.curr.index; }
+        bool operator!=(const iterator &other) const { return curr.index != other.curr.index; }
+        iterator &operator++() {
+            if (!inst->simple_layout)
+                curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs;
+            ++curr.index;
+            curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr;
+            return *this;
+        }
+        value_and_holder &operator*() { return curr; }
+        value_and_holder *operator->() { return &curr; }
+    };
+
+    iterator begin() { return iterator(inst, &tinfo); }
+    iterator end() { return iterator(tinfo.size()); }
+
+    iterator find(const type_info *find_type) {
+        auto it = begin(), endit = end();
+        while (it != endit && it->type != find_type) ++it;
+        return it;
+    }
+
+    size_t size() { return tinfo.size(); }
+};
+
+/**
+ * Extracts C++ value and holder pointer references from an instance (which may contain multiple
+ * values/holders for python-side multiple inheritance) that match the given type.  Throws an error
+ * if the given type (or ValueType, if omitted) is not a pybind11 base of the given instance.  If
+ * `find_type` is omitted (or explicitly specified as nullptr) the first value/holder are returned,
+ * regardless of type (and the resulting .type will be nullptr).
+ *
+ * The returned object should be short-lived: in particular, it must not outlive the called-upon
+ * instance.
+ */
+PYBIND11_NOINLINE inline value_and_holder instance::get_value_and_holder(const type_info *find_type /*= nullptr default in common.h*/, bool throw_if_missing /*= true in common.h*/) {
+    // Optimize common case:
+    if (!find_type || Py_TYPE(this) == find_type->type)
+        return value_and_holder(this, find_type, 0, 0);
+
+    detail::values_and_holders vhs(this);
+    auto it = vhs.find(find_type);
+    if (it != vhs.end())
+        return *it;
+
+    if (!throw_if_missing)
+        return value_and_holder();
+
+#if defined(NDEBUG)
+    pybind11_fail("pybind11::detail::instance::get_value_and_holder: "
+            "type is not a pybind11 base of the given instance "
+            "(compile in debug mode for type details)");
+#else
+    pybind11_fail("pybind11::detail::instance::get_value_and_holder: `" +
+            get_fully_qualified_tp_name(find_type->type) + "' is not a pybind11 base of the given `" +
+            get_fully_qualified_tp_name(Py_TYPE(this)) + "' instance");
+#endif
+}
+
+PYBIND11_NOINLINE inline void instance::allocate_layout() {
+    auto &tinfo = all_type_info(Py_TYPE(this));
+
+    const size_t n_types = tinfo.size();
+
+    if (n_types == 0)
+        pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types");
+
+    simple_layout =
+        n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs();
+
+    // Simple path: no python-side multiple inheritance, and a small-enough holder
+    if (simple_layout) {
+        simple_value_holder[0] = nullptr;
+        simple_holder_constructed = false;
+        simple_instance_registered = false;
+    }
+    else { // multiple base types or a too-large holder
+        // Allocate space to hold: [v1*][h1][v2*][h2]...[bb...] where [vN*] is a value pointer,
+        // [hN] is the (uninitialized) holder instance for value N, and [bb...] is a set of bool
+        // values that tracks whether each associated holder has been initialized.  Each [block] is
+        // padded, if necessary, to an integer multiple of sizeof(void *).
+        size_t space = 0;
+        for (auto t : tinfo) {
+            space += 1; // value pointer
+            space += t->holder_size_in_ptrs; // holder instance
+        }
+        size_t flags_at = space;
+        space += size_in_ptrs(n_types); // status bytes (holder_constructed and instance_registered)
+
+        // Allocate space for flags, values, and holders, and initialize it to 0 (flags and values,
+        // in particular, need to be 0).  Use Python's memory allocation functions: in Python 3.6
+        // they default to using pymalloc, which is designed to be efficient for small allocations
+        // like the one we're doing here; in earlier versions (and for larger allocations) they are
+        // just wrappers around malloc.
+#if PY_VERSION_HEX >= 0x03050000
+        nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
+        if (!nonsimple.values_and_holders) throw std::bad_alloc();
+#else
+        nonsimple.values_and_holders = (void **) PyMem_New(void *, space);
+        if (!nonsimple.values_and_holders) throw std::bad_alloc();
+        std::memset(nonsimple.values_and_holders, 0, space * sizeof(void *));
+#endif
+        nonsimple.status = reinterpret_cast<uint8_t *>(&nonsimple.values_and_holders[flags_at]);
+    }
+    owned = true;
+}
+
+PYBIND11_NOINLINE inline void instance::deallocate_layout() {
+    if (!simple_layout)
+        PyMem_Free(nonsimple.values_and_holders);
+}
+
 PYBIND11_NOINLINE inline bool isinstance_generic(handle obj, const std::type_info &tp) {
     handle type = detail::get_type_handle(tp, false);
     if (!type)
@@ -147,7 +432,7 @@ PYBIND11_NOINLINE inline std::string error_string() {
 
 #if !defined(PYPY_VERSION)
     if (scope.trace) {
-        PyTracebackObject *trace = (PyTracebackObject *) scope.trace;
+        auto *trace = (PyTracebackObject *) scope.trace;
 
         /* Get the deepest trace possible */
         while (trace->tb_next)
@@ -163,7 +448,6 @@ PYBIND11_NOINLINE inline std::string error_string() {
                 handle(frame->f_code->co_name).cast<std::string>() + "\n";
             frame = frame->f_back;
         }
-        trace = trace->tb_next;
     }
 #endif
 
@@ -174,9 +458,10 @@ PYBIND11_NOINLINE inline handle get_object_handle(const void *ptr, const detail:
     auto &instances = get_internals().registered_instances;
     auto range = instances.equal_range(ptr);
     for (auto it = range.first; it != range.second; ++it) {
-        auto instance_type = detail::get_type_info(Py_TYPE(it->second));
-        if (instance_type && instance_type == type)
-            return handle((PyObject *) it->second);
+        for (const auto &vh : values_and_holders(it->second)) {
+            if (vh.type == type)
+                return handle((PyObject *) it->second);
+        }
     }
     return handle();
 }
@@ -195,181 +480,312 @@ inline PyThreadState *get_thread_state_unchecked() {
 #endif
 }
 
-// Forward declaration
+// Forward declarations
 inline void keep_alive_impl(handle nurse, handle patient);
+inline PyObject *make_new_instance(PyTypeObject *type);
 
 class type_caster_generic {
 public:
     PYBIND11_NOINLINE type_caster_generic(const std::type_info &type_info)
-     : typeinfo(get_type_info(type_info)) { }
-
-    PYBIND11_NOINLINE bool load(handle src, bool convert) {
-        if (!src)
-            return false;
-        return load(src, convert, Py_TYPE(src.ptr()));
-    }
-
-    bool load(handle src, bool convert, PyTypeObject *tobj) {
-        if (!src || !typeinfo)
-            return false;
-        if (src.is_none()) {
-            value = nullptr;
-            return true;
-        }
-
-        if (typeinfo->simple_type) { /* Case 1: no multiple inheritance etc. involved */
-            /* Check if we can safely perform a reinterpret-style cast */
-            if (PyType_IsSubtype(tobj, typeinfo->type)) {
-                value = reinterpret_cast<instance<void> *>(src.ptr())->value;
-                return true;
-            }
-        } else { /* Case 2: multiple inheritance */
-            /* Check if we can safely perform a reinterpret-style cast */
-            if (tobj == typeinfo->type) {
-                value = reinterpret_cast<instance<void> *>(src.ptr())->value;
-                return true;
-            }
-
-            /* If this is a python class, also check the parents recursively */
-            auto const &type_dict = get_internals().registered_types_py;
-            bool new_style_class = PyType_Check((PyObject *) tobj);
-            if (type_dict.find(tobj) == type_dict.end() && new_style_class && tobj->tp_bases) {
-                auto parents = reinterpret_borrow<tuple>(tobj->tp_bases);
-                for (handle parent : parents) {
-                    bool result = load(src, convert, (PyTypeObject *) parent.ptr());
-                    if (result)
-                        return true;
-                }
-            }
+        : typeinfo(get_type_info(type_info)), cpptype(&type_info) { }
 
-            /* Try implicit casts */
-            for (auto &cast : typeinfo->implicit_casts) {
-                type_caster_generic sub_caster(*cast.first);
-                if (sub_caster.load(src, convert)) {
-                    value = cast.second(sub_caster.value);
-                    return true;
-                }
-            }
-        }
+    type_caster_generic(const type_info *typeinfo)
+        : typeinfo(typeinfo), cpptype(typeinfo ? typeinfo->cpptype : nullptr) { }
 
-        /* Perform an implicit conversion */
-        if (convert) {
-            for (auto &converter : typeinfo->implicit_conversions) {
-                temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
-                if (load(temp, false))
-                    return true;
-            }
-            for (auto &converter : *typeinfo->direct_conversions) {
-                if (converter(src.ptr(), value))
-                    return true;
-            }
-        }
-        return false;
+    bool load(handle src, bool convert) {
+        return load_impl<type_caster_generic>(src, convert);
     }
 
     PYBIND11_NOINLINE static handle cast(const void *_src, return_value_policy policy, handle parent,
-                                         const std::type_info *type_info,
-                                         const std::type_info *type_info_backup,
+                                         const detail::type_info *tinfo,
                                          void *(*copy_constructor)(const void *),
                                          void *(*move_constructor)(const void *),
                                          const void *existing_holder = nullptr) {
-        void *src = const_cast<void *>(_src);
-        if (src == nullptr)
-            return none().inc_ref();
-
-        auto &internals = get_internals();
-
-        auto it = internals.registered_types_cpp.find(std::type_index(*type_info));
-        if (it == internals.registered_types_cpp.end()) {
-            type_info = type_info_backup;
-            it = internals.registered_types_cpp.find(std::type_index(*type_info));
-        }
-
-        if (it == internals.registered_types_cpp.end()) {
-            std::string tname = type_info->name();
-            detail::clean_type_id(tname);
-            std::string msg = "Unregistered type : " + tname;
-            PyErr_SetString(PyExc_TypeError, msg.c_str());
+        if (!tinfo) // no type info: error will be set already
             return handle();
-        }
 
-        auto tinfo = (const detail::type_info *) it->second;
+        void *src = const_cast<void *>(_src);
+        if (src == nullptr)
+            return none().release();
 
-        auto it_instances = internals.registered_instances.equal_range(src);
+        auto it_instances = get_internals().registered_instances.equal_range(src);
         for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
-            auto instance_type = detail::get_type_info(Py_TYPE(it_i->second));
-            if (instance_type && instance_type == tinfo)
-                return handle((PyObject *) it_i->second).inc_ref();
+            for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
+                if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype))
+                    return handle((PyObject *) it_i->second).inc_ref();
+            }
         }
 
-        auto inst = reinterpret_steal<object>(PyType_GenericAlloc(tinfo->type, 0));
-
-        auto wrapper = (instance<void> *) inst.ptr();
-
-        wrapper->value = nullptr;
+        auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
+        auto wrapper = reinterpret_cast<instance *>(inst.ptr());
         wrapper->owned = false;
+        void *&valueptr = values_and_holders(wrapper).begin()->value_ptr();
 
         switch (policy) {
             case return_value_policy::automatic:
             case return_value_policy::take_ownership:
-                wrapper->value = src;
+                valueptr = src;
                 wrapper->owned = true;
                 break;
 
             case return_value_policy::automatic_reference:
             case return_value_policy::reference:
-                wrapper->value = src;
+                valueptr = src;
                 wrapper->owned = false;
                 break;
 
             case return_value_policy::copy:
                 if (copy_constructor)
-                    wrapper->value = copy_constructor(src);
-                else
-                    throw cast_error("return_value_policy = copy, but the "
-                                     "object is non-copyable!");
+                    valueptr = copy_constructor(src);
+                else {
+#if defined(NDEBUG)
+                    throw cast_error("return_value_policy = copy, but type is "
+                                     "non-copyable! (compile in debug mode for details)");
+#else
+                    std::string type_name(tinfo->cpptype->name());
+                    detail::clean_type_id(type_name);
+                    throw cast_error("return_value_policy = copy, but type " +
+                                     type_name + " is non-copyable!");
+#endif
+                }
                 wrapper->owned = true;
                 break;
 
             case return_value_policy::move:
                 if (move_constructor)
-                    wrapper->value = move_constructor(src);
+                    valueptr = move_constructor(src);
                 else if (copy_constructor)
-                    wrapper->value = copy_constructor(src);
-                else
-                    throw cast_error("return_value_policy = move, but the "
-                                     "object is neither movable nor copyable!");
+                    valueptr = copy_constructor(src);
+                else {
+#if defined(NDEBUG)
+                    throw cast_error("return_value_policy = move, but type is neither "
+                                     "movable nor copyable! "
+                                     "(compile in debug mode for details)");
+#else
+                    std::string type_name(tinfo->cpptype->name());
+                    detail::clean_type_id(type_name);
+                    throw cast_error("return_value_policy = move, but type " +
+                                     type_name + " is neither movable nor copyable!");
+#endif
+                }
                 wrapper->owned = true;
                 break;
 
             case return_value_policy::reference_internal:
-                wrapper->value = src;
+                valueptr = src;
                 wrapper->owned = false;
-                detail::keep_alive_impl(inst, parent);
+                keep_alive_impl(inst, parent);
                 break;
 
             default:
                 throw cast_error("unhandled return_value_policy: should not happen!");
         }
 
-        tinfo->init_holder(inst.ptr(), existing_holder);
-
-        internals.registered_instances.emplace(wrapper->value, inst.ptr());
+        tinfo->init_instance(wrapper, existing_holder);
 
         return inst.release();
     }
 
-protected:
+    // Base methods for generic caster; there are overridden in copyable_holder_caster
+    void load_value(value_and_holder &&v_h) {
+        auto *&vptr = v_h.value_ptr();
+        // Lazy allocation for unallocated values:
+        if (vptr == nullptr) {
+            auto *type = v_h.type ? v_h.type : typeinfo;
+            if (type->operator_new) {
+                vptr = type->operator_new(type->type_size);
+            } else {
+                #if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
+                    if (type->type_align > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
+                        vptr = ::operator new(type->type_size,
+                                              std::align_val_t(type->type_align));
+                    else
+                #endif
+                vptr = ::operator new(type->type_size);
+            }
+        }
+        value = vptr;
+    }
+    bool try_implicit_casts(handle src, bool convert) {
+        for (auto &cast : typeinfo->implicit_casts) {
+            type_caster_generic sub_caster(*cast.first);
+            if (sub_caster.load(src, convert)) {
+                value = cast.second(sub_caster.value);
+                return true;
+            }
+        }
+        return false;
+    }
+    bool try_direct_conversions(handle src) {
+        for (auto &converter : *typeinfo->direct_conversions) {
+            if (converter(src.ptr(), value))
+                return true;
+        }
+        return false;
+    }
+    void check_holder_compat() {}
+
+    PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
+        auto caster = type_caster_generic(ti);
+        if (caster.load(src, false))
+            return caster.value;
+        return nullptr;
+    }
+
+    /// Try to load with foreign typeinfo, if available. Used when there is no
+    /// native typeinfo, or when the native one wasn't able to produce a value.
+    PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) {
+        constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID;
+        const auto pytype = type::handle_of(src);
+        if (!hasattr(pytype, local_key))
+            return false;
+
+        type_info *foreign_typeinfo = reinterpret_borrow<capsule>(getattr(pytype, local_key));
+        // Only consider this foreign loader if actually foreign and is a loader of the correct cpp type
+        if (foreign_typeinfo->module_local_load == &local_load
+            || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
+            return false;
+
+        if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) {
+            value = result;
+            return true;
+        }
+        return false;
+    }
+
+    // Implementation of `load`; this takes the type of `this` so that it can dispatch the relevant
+    // bits of code between here and copyable_holder_caster where the two classes need different
+    // logic (without having to resort to virtual inheritance).
+    template <typename ThisT>
+    PYBIND11_NOINLINE bool load_impl(handle src, bool convert) {
+        if (!src) return false;
+        if (!typeinfo) return try_load_foreign_module_local(src);
+        if (src.is_none()) {
+            // Defer accepting None to other overloads (if we aren't in convert mode):
+            if (!convert) return false;
+            value = nullptr;
+            return true;
+        }
+
+        auto &this_ = static_cast<ThisT &>(*this);
+        this_.check_holder_compat();
+
+        PyTypeObject *srctype = Py_TYPE(src.ptr());
+
+        // Case 1: If src is an exact type match for the target type then we can reinterpret_cast
+        // the instance's value pointer to the target type:
+        if (srctype == typeinfo->type) {
+            this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
+            return true;
+        }
+        // Case 2: We have a derived class
+        else if (PyType_IsSubtype(srctype, typeinfo->type)) {
+            auto &bases = all_type_info(srctype);
+            bool no_cpp_mi = typeinfo->simple_type;
+
+            // Case 2a: the python type is a Python-inherited derived class that inherits from just
+            // one simple (no MI) pybind11 class, or is an exact match, so the C++ instance is of
+            // the right type and we can use reinterpret_cast.
+            // (This is essentially the same as case 2b, but because not using multiple inheritance
+            // is extremely common, we handle it specially to avoid the loop iterator and type
+            // pointer lookup overhead)
+            if (bases.size() == 1 && (no_cpp_mi || bases.front()->type == typeinfo->type)) {
+                this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder());
+                return true;
+            }
+            // Case 2b: the python type inherits from multiple C++ bases.  Check the bases to see if
+            // we can find an exact match (or, for a simple C++ type, an inherited match); if so, we
+            // can safely reinterpret_cast to the relevant pointer.
+            else if (bases.size() > 1) {
+                for (auto base : bases) {
+                    if (no_cpp_mi ? PyType_IsSubtype(base->type, typeinfo->type) : base->type == typeinfo->type) {
+                        this_.load_value(reinterpret_cast<instance *>(src.ptr())->get_value_and_holder(base));
+                        return true;
+                    }
+                }
+            }
+
+            // Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match
+            // in the registered bases, above, so try implicit casting (needed for proper C++ casting
+            // when MI is involved).
+            if (this_.try_implicit_casts(src, convert))
+                return true;
+        }
+
+        // Perform an implicit conversion
+        if (convert) {
+            for (auto &converter : typeinfo->implicit_conversions) {
+                auto temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
+                if (load_impl<ThisT>(temp, false)) {
+                    loader_life_support::add_patient(temp);
+                    return true;
+                }
+            }
+            if (this_.try_direct_conversions(src))
+                return true;
+        }
+
+        // Failed to match local typeinfo. Try again with global.
+        if (typeinfo->module_local) {
+            if (auto gtype = get_global_type_info(*typeinfo->cpptype)) {
+                typeinfo = gtype;
+                return load(src, false);
+            }
+        }
+
+        // Global typeinfo has precedence over foreign module_local
+        return try_load_foreign_module_local(src);
+    }
+
+
+    // Called to do type lookup and wrap the pointer and type in a pair when a dynamic_cast
+    // isn't needed or can't be used.  If the type is unknown, sets the error and returns a pair
+    // with .second = nullptr.  (p.first = nullptr is not an error: it becomes None).
+    PYBIND11_NOINLINE static std::pair<const void *, const type_info *> src_and_type(
+            const void *src, const std::type_info &cast_type, const std::type_info *rtti_type = nullptr) {
+        if (auto *tpi = get_type_info(cast_type))
+            return {src, const_cast<const type_info *>(tpi)};
+
+        // Not found, set error:
+        std::string tname = rtti_type ? rtti_type->name() : cast_type.name();
+        detail::clean_type_id(tname);
+        std::string msg = "Unregistered type : " + tname;
+        PyErr_SetString(PyExc_TypeError, msg.c_str());
+        return {nullptr, nullptr};
+    }
+
     const type_info *typeinfo = nullptr;
+    const std::type_info *cpptype = nullptr;
     void *value = nullptr;
-    object temp;
 };
 
-/* Determine suitable casting operator */
+/**
+ * Determine suitable casting operator for pointer-or-lvalue-casting type casters.  The type caster
+ * needs to provide `operator T*()` and `operator T&()` operators.
+ *
+ * If the type supports moving the value away via an `operator T&&() &&` method, it should use
+ * `movable_cast_op_type` instead.
+ */
+template <typename T>
+using cast_op_type =
+    conditional_t<std::is_pointer<remove_reference_t<T>>::value,
+        typename std::add_pointer<intrinsic_t<T>>::type,
+        typename std::add_lvalue_reference<intrinsic_t<T>>::type>;
+
+/**
+ * Determine suitable casting operator for a type caster with a movable value.  Such a type caster
+ * needs to provide `operator T*()`, `operator T&()`, and `operator T&&() &&`.  The latter will be
+ * called in appropriate contexts where the value can be moved rather than copied.
+ *
+ * These operator are automatically provided when using the PYBIND11_TYPE_CASTER macro.
+ */
 template <typename T>
-using cast_op_type = typename std::conditional<std::is_pointer<typename std::remove_reference<T>::type>::value,
-    typename std::add_pointer<intrinsic_t<T>>::type,
-    typename std::add_lvalue_reference<intrinsic_t<T>>::type>::type;
+using movable_cast_op_type =
+    conditional_t<std::is_pointer<typename std::remove_reference<T>::type>::value,
+        typename std::add_pointer<intrinsic_t<T>>::type,
+    conditional_t<std::is_rvalue_reference<T>::value,
+        typename std::add_rvalue_reference<intrinsic_t<T>>::type,
+        typename std::add_lvalue_reference<intrinsic_t<T>>::type>>;
 
 // std::is_copy_constructible isn't quite enough: it lets std::vector<T> (and similar) through when
 // T is non-copyable, but code containing such a copy constructor fails to actually compile.
@@ -378,16 +794,75 @@ template <typename T, typename SFINAE = void> struct is_copy_constructible : std
 // Specialization for types that appear to be copy constructible but also look like stl containers
 // (we specifically check for: has `value_type` and `reference` with `reference = value_type&`): if
 // so, copy constructability depends on whether the value_type is copy constructible.
-template <typename Container> struct is_copy_constructible<Container, enable_if_t<
-        std::is_copy_constructible<Container>::value &&
-        std::is_same<typename Container::value_type &, typename Container::reference>::value
-    >> : std::is_copy_constructible<typename Container::value_type> {};
+template <typename Container> struct is_copy_constructible<Container, enable_if_t<all_of<
+        std::is_copy_constructible<Container>,
+        std::is_same<typename Container::value_type &, typename Container::reference>,
+        // Avoid infinite recursion
+        negation<std::is_same<Container, typename Container::value_type>>
+    >::value>> : is_copy_constructible<typename Container::value_type> {};
+
+// Likewise for std::pair
+// (after C++17 it is mandatory that the copy constructor not exist when the two types aren't themselves
+// copy constructible, but this can not be relied upon when T1 or T2 are themselves containers).
+template <typename T1, typename T2> struct is_copy_constructible<std::pair<T1, T2>>
+    : all_of<is_copy_constructible<T1>, is_copy_constructible<T2>> {};
+
+// The same problems arise with std::is_copy_assignable, so we use the same workaround.
+template <typename T, typename SFINAE = void> struct is_copy_assignable : std::is_copy_assignable<T> {};
+template <typename Container> struct is_copy_assignable<Container, enable_if_t<all_of<
+        std::is_copy_assignable<Container>,
+        std::is_same<typename Container::value_type &, typename Container::reference>
+    >::value>> : is_copy_assignable<typename Container::value_type> {};
+template <typename T1, typename T2> struct is_copy_assignable<std::pair<T1, T2>>
+    : all_of<is_copy_assignable<T1>, is_copy_assignable<T2>> {};
+
+PYBIND11_NAMESPACE_END(detail)
+
+// polymorphic_type_hook<itype>::get(src, tinfo) determines whether the object pointed
+// to by `src` actually is an instance of some class derived from `itype`.
+// If so, it sets `tinfo` to point to the std::type_info representing that derived
+// type, and returns a pointer to the start of the most-derived object of that type
+// (in which `src` is a subobject; this will be the same address as `src` in most
+// single inheritance cases). If not, or if `src` is nullptr, it simply returns `src`
+// and leaves `tinfo` at its default value of nullptr.
+//
+// The default polymorphic_type_hook just returns src. A specialization for polymorphic
+// types determines the runtime type of the passed object and adjusts the this-pointer
+// appropriately via dynamic_cast<void*>. This is what enables a C++ Animal* to appear
+// to Python as a Dog (if Dog inherits from Animal, Animal is polymorphic, Dog is
+// registered with pybind11, and this Animal is in fact a Dog).
+//
+// You may specialize polymorphic_type_hook yourself for types that want to appear
+// polymorphic to Python but do not use C++ RTTI. (This is a not uncommon pattern
+// in performance-sensitive applications, used most notably in LLVM.)
+//
+// polymorphic_type_hook_base allows users to specialize polymorphic_type_hook with
+// std::enable_if. User provided specializations will always have higher priority than
+// the default implementation and specialization provided in polymorphic_type_hook_base.
+template <typename itype, typename SFINAE = void>
+struct polymorphic_type_hook_base
+{
+    static const void *get(const itype *src, const std::type_info*&) { return src; }
+};
+template <typename itype>
+struct polymorphic_type_hook_base<itype, detail::enable_if_t<std::is_polymorphic<itype>::value>>
+{
+    static const void *get(const itype *src, const std::type_info*& type) {
+        type = src ? &typeid(*src) : nullptr;
+        return dynamic_cast<const void*>(src);
+    }
+};
+template <typename itype, typename SFINAE = void>
+struct polymorphic_type_hook : public polymorphic_type_hook_base<itype> {};
+
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 /// Generic type caster for objects stored on the heap
 template <typename type> class type_caster_base : public type_caster_generic {
     using itype = intrinsic_t<type>;
+
 public:
-    static PYBIND11_DESCR name() { return type_descr(_<type>()); }
+    static constexpr auto name = _<type>();
 
     type_caster_base() : type_caster_base(typeid(type)) { }
     explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
@@ -402,43 +877,67 @@ template <typename type> class type_caster_base : public type_caster_generic {
         return cast(&src, return_value_policy::move, parent);
     }
 
+    // Returns a (pointer, type_info) pair taking care of necessary type lookup for a
+    // polymorphic type (using RTTI by default, but can be overridden by specializing
+    // polymorphic_type_hook). If the instance isn't derived, returns the base version.
+    static std::pair<const void *, const type_info *> src_and_type(const itype *src) {
+        auto &cast_type = typeid(itype);
+        const std::type_info *instance_type = nullptr;
+        const void *vsrc = polymorphic_type_hook<itype>::get(src, instance_type);
+        if (instance_type && !same_type(cast_type, *instance_type)) {
+            // This is a base pointer to a derived type. If the derived type is registered
+            // with pybind11, we want to make the full derived object available.
+            // In the typical case where itype is polymorphic, we get the correct
+            // derived pointer (which may be != base pointer) by a dynamic_cast to
+            // most derived type. If itype is not polymorphic, we won't get here
+            // except via a user-provided specialization of polymorphic_type_hook,
+            // and the user has promised that no this-pointer adjustment is
+            // required in that case, so it's OK to use static_cast.
+            if (const auto *tpi = get_type_info(*instance_type))
+                return {vsrc, tpi};
+        }
+        // Otherwise we have either a nullptr, an `itype` pointer, or an unknown derived pointer, so
+        // don't do a cast
+        return type_caster_generic::src_and_type(src, cast_type, instance_type);
+    }
+
     static handle cast(const itype *src, return_value_policy policy, handle parent) {
+        auto st = src_and_type(src);
         return type_caster_generic::cast(
-            src, policy, parent, src ? &typeid(*src) : nullptr, &typeid(type),
+            st.first, policy, parent, st.second,
             make_copy_constructor(src), make_move_constructor(src));
     }
 
     static handle cast_holder(const itype *src, const void *holder) {
+        auto st = src_and_type(src);
         return type_caster_generic::cast(
-            src, return_value_policy::take_ownership, {},
-            src ? &typeid(*src) : nullptr, &typeid(type),
+            st.first, return_value_policy::take_ownership, {}, st.second,
             nullptr, nullptr, holder);
     }
 
-    template <typename T> using cast_op_type = pybind11::detail::cast_op_type<T>;
+    template <typename T> using cast_op_type = detail::cast_op_type<T>;
 
     operator itype*() { return (type *) value; }
     operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
 
 protected:
-    typedef void *(*Constructor)(const void *stream);
-#if !defined(_MSC_VER)
+    using Constructor = void *(*)(const void *);
+
     /* Only enabled when the types are {copy,move}-constructible *and* when the type
-       does not have a private operator new implementaton. */
-    template <typename T = type, typename = enable_if_t<is_copy_constructible<T>::value>> static auto make_copy_constructor(const T *value) -> decltype(new T(*value), Constructor(nullptr)) {
-        return [](const void *arg) -> void * { return new T(*((const T *) arg)); }; }
-    template <typename T = type> static auto make_move_constructor(const T *value) -> decltype(new T(std::move(*((T *) value))), Constructor(nullptr)) {
-        return [](const void *arg) -> void * { return (void *) new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg)))); }; }
-#else
-    /* Visual Studio 2015's SFINAE implementation doesn't yet handle the above robustly in all situations.
-       Use a workaround that only tests for constructibility for now. */
-    template <typename T = type, typename = enable_if_t<is_copy_constructible<T>::value>>
-    static Constructor make_copy_constructor(const T *value) {
-        return [](const void *arg) -> void * { return new T(*((const T *)arg)); }; }
-    template <typename T = type, typename = enable_if_t<std::is_move_constructible<T>::value>>
-    static Constructor make_move_constructor(const T *value) {
-        return [](const void *arg) -> void * { return (void *) new T(std::move(*((T *)arg))); }; }
-#endif
+       does not have a private operator new implementation. */
+    template <typename T, typename = enable_if_t<is_copy_constructible<T>::value>>
+    static auto make_copy_constructor(const T *x) -> decltype(new T(*x), Constructor{}) {
+        return [](const void *arg) -> void * {
+            return new T(*reinterpret_cast<const T *>(arg));
+        };
+    }
+
+    template <typename T, typename = enable_if_t<std::is_move_constructible<T>::value>>
+    static auto make_move_constructor(const T *x) -> decltype(new T(std::move(*const_cast<T *>(x))), Constructor{}) {
+        return [](const void *arg) -> void * {
+            return new T(std::move(*const_cast<T *>(reinterpret_cast<const T *>(arg))));
+        };
+    }
 
     static Constructor make_copy_constructor(...) { return nullptr; }
     static Constructor make_move_constructor(...) { return nullptr; }
@@ -451,40 +950,63 @@ template <typename type> using make_caster = type_caster<intrinsic_t<type>>;
 template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
     return caster.operator typename make_caster<T>::template cast_op_type<T>();
 }
-template <typename T> typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &&caster) {
-    return cast_op<T>(caster);
+template <typename T> typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
+cast_op(make_caster<T> &&caster) {
+    return std::move(caster).operator
+        typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>();
 }
 
-template <typename type> class type_caster<std::reference_wrapper<type>> : public type_caster_base<type> {
+template <typename type> class type_caster<std::reference_wrapper<type>> {
+private:
+    using caster_t = make_caster<type>;
+    caster_t subcaster;
+    using subcaster_cast_op_type = typename caster_t::template cast_op_type<type>;
+    static_assert(std::is_same<typename std::remove_const<type>::type &, subcaster_cast_op_type>::value,
+            "std::reference_wrapper<T> caster requires T to have a caster with an `T &` operator");
 public:
+    bool load(handle src, bool convert) { return subcaster.load(src, convert); }
+    static constexpr auto name = caster_t::name;
     static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
-        return type_caster_base<type>::cast(&src.get(), policy, parent);
+        // It is definitely wrong to take ownership of this pointer, so mask that rvp
+        if (policy == return_value_policy::take_ownership || policy == return_value_policy::automatic)
+            policy = return_value_policy::automatic_reference;
+        return caster_t::cast(&src.get(), policy, parent);
     }
     template <typename T> using cast_op_type = std::reference_wrapper<type>;
-    operator std::reference_wrapper<type>() { return std::ref(*((type *) this->value)); }
+    operator std::reference_wrapper<type>() { return subcaster.operator subcaster_cast_op_type&(); }
 };
 
 #define PYBIND11_TYPE_CASTER(type, py_name) \
     protected: \
         type value; \
     public: \
-        static PYBIND11_DESCR name() { return type_descr(py_name); } \
-        static handle cast(const type *src, return_value_policy policy, handle parent) { \
+        static constexpr auto name = py_name; \
+        template <typename T_, enable_if_t<std::is_same<type, remove_cv_t<T_>>::value, int> = 0> \
+        static handle cast(T_ *src, return_value_policy policy, handle parent) { \
             if (!src) return none().release(); \
-            return cast(*src, policy, parent); \
+            if (policy == return_value_policy::take_ownership) { \
+                auto h = cast(std::move(*src), policy, parent); delete src; return h; \
+            } else { \
+                return cast(*src, policy, parent); \
+            } \
         } \
         operator type*() { return &value; } \
         operator type&() { return value; } \
-        template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>
+        operator type&&() && { return std::move(value); } \
+        template <typename T_> using cast_op_type = pybind11::detail::movable_cast_op_type<T_>
 
 
 template <typename CharT> using is_std_char_type = any_of<
     std::is_same<CharT, char>, /* std::string */
+#if defined(PYBIND11_HAS_U8STRING)
+    std::is_same<CharT, char8_t>, /* std::u8string */
+#endif
     std::is_same<CharT, char16_t>, /* std::u16string */
     std::is_same<CharT, char32_t>, /* std::u32string */
     std::is_same<CharT, wchar_t> /* std::wstring */
 >;
 
+
 template <typename T>
 struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_type<T>::value>> {
     using _py_type_0 = conditional_t<sizeof(T) <= sizeof(long), long, long long>;
@@ -503,36 +1025,34 @@ struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_t
                 py_value = (py_type) PyFloat_AsDouble(src.ptr());
             else
                 return false;
-        } else if (sizeof(T) <= sizeof(long)) {
-            if (PyFloat_Check(src.ptr()))
-                return false;
-            if (std::is_signed<T>::value)
-                py_value = (py_type) PyLong_AsLong(src.ptr());
-            else
-                py_value = (py_type) PyLong_AsUnsignedLong(src.ptr());
-        } else {
-            if (PyFloat_Check(src.ptr()))
-                return false;
-            if (std::is_signed<T>::value)
-                py_value = (py_type) PYBIND11_LONG_AS_LONGLONG(src.ptr());
-            else
-                py_value = (py_type) PYBIND11_LONG_AS_UNSIGNED_LONGLONG(src.ptr());
+        } else if (PyFloat_Check(src.ptr())) {
+            return false;
+        } else if (std::is_unsigned<py_type>::value) {
+            py_value = as_unsigned<py_type>(src.ptr());
+        } else { // signed integer:
+            py_value = sizeof(T) <= sizeof(long)
+                ? (py_type) PyLong_AsLong(src.ptr())
+                : (py_type) PYBIND11_LONG_AS_LONGLONG(src.ptr());
         }
 
-        if ((py_value == (py_type) -1 && PyErr_Occurred()) ||
-            (std::is_integral<T>::value && sizeof(py_type) != sizeof(T) &&
-               (py_value < (py_type) std::numeric_limits<T>::min() ||
-                py_value > (py_type) std::numeric_limits<T>::max()))) {
-#if PY_VERSION_HEX < 0x03000000
-            bool type_error = PyErr_ExceptionMatches(PyExc_SystemError);
+        // Python API reported an error
+        bool py_err = py_value == (py_type) -1 && PyErr_Occurred();
+
+        // Check to see if the conversion is valid (integers should match exactly)
+        // Signed/unsigned checks happen elsewhere
+        if (py_err || (std::is_integral<T>::value && sizeof(py_type) != sizeof(T) && py_value != (py_type) (T) py_value)) {
+            bool type_error = py_err && PyErr_ExceptionMatches(
+#if PY_VERSION_HEX < 0x03000000 && !defined(PYPY_VERSION)
+                PyExc_SystemError
 #else
-            bool type_error = PyErr_ExceptionMatches(PyExc_TypeError);
+                PyExc_TypeError
 #endif
+            );
             PyErr_Clear();
             if (type_error && convert && PyNumber_Check(src.ptr())) {
-                auto tmp = reinterpret_borrow<object>(std::is_floating_point<T>::value
-                                                      ? PyNumber_Float(src.ptr())
-                                                      : PyNumber_Long(src.ptr()));
+                auto tmp = reinterpret_steal<object>(std::is_floating_point<T>::value
+                                                     ? PyNumber_Float(src.ptr())
+                                                     : PyNumber_Long(src.ptr()));
                 PyErr_Clear();
                 return load(tmp, false);
             }
@@ -543,20 +1063,34 @@ struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_t
         return true;
     }
 
-    static handle cast(T src, return_value_policy /* policy */, handle /* parent */) {
-        if (std::is_floating_point<T>::value) {
-            return PyFloat_FromDouble((double) src);
-        } else if (sizeof(T) <= sizeof(long)) {
-            if (std::is_signed<T>::value)
-                return PyLong_FromLong((long) src);
-            else
-                return PyLong_FromUnsignedLong((unsigned long) src);
-        } else {
-            if (std::is_signed<T>::value)
-                return PyLong_FromLongLong((long long) src);
-            else
-                return PyLong_FromUnsignedLongLong((unsigned long long) src);
-        }
+    template<typename U = T>
+    static typename std::enable_if<std::is_floating_point<U>::value, handle>::type
+    cast(U src, return_value_policy /* policy */, handle /* parent */) {
+        return PyFloat_FromDouble((double) src);
+    }
+
+    template<typename U = T>
+    static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value && (sizeof(U) <= sizeof(long)), handle>::type
+    cast(U src, return_value_policy /* policy */, handle /* parent */) {
+        return PYBIND11_LONG_FROM_SIGNED((long) src);
+    }
+
+    template<typename U = T>
+    static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value && (sizeof(U) <= sizeof(unsigned long)), handle>::type
+    cast(U src, return_value_policy /* policy */, handle /* parent */) {
+        return PYBIND11_LONG_FROM_UNSIGNED((unsigned long) src);
+    }
+
+    template<typename U = T>
+    static typename std::enable_if<!std::is_floating_point<U>::value && std::is_signed<U>::value && (sizeof(U) > sizeof(long)), handle>::type
+    cast(U src, return_value_policy /* policy */, handle /* parent */) {
+        return PyLong_FromLongLong((long long) src);
+    }
+
+    template<typename U = T>
+    static typename std::enable_if<!std::is_floating_point<U>::value && std::is_unsigned<U>::value && (sizeof(U) > sizeof(unsigned long)), handle>::type
+    cast(U src, return_value_policy /* policy */, handle /* parent */) {
+        return PyLong_FromUnsignedLongLong((unsigned long long) src);
     }
 
     PYBIND11_TYPE_CASTER(T, _<std::is_integral<T>::value>("int", "float"));
@@ -564,7 +1098,11 @@ struct type_caster<T, enable_if_t<std::is_arithmetic<T>::value && !is_std_char_t
 
 template<typename T> struct void_caster {
 public:
-    bool load(handle, bool) { return false; }
+    bool load(handle src, bool) {
+        if (src && src.is_none())
+            return true;
+        return false;
+    }
     static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
         return none().inc_ref();
     }
@@ -592,8 +1130,9 @@ template <> class type_caster<void> : public type_caster<void_type> {
         }
 
         /* Check if this is a C++ type */
-        if (get_type_info((PyTypeObject *) h.get_type().ptr())) {
-            value = ((instance<void> *) h.ptr())->value;
+        auto &bases = all_type_info((PyTypeObject *) type::handle_of(h).ptr());
+        if (bases.size() == 1) { // Only allowing loading from a single-value type
+            value = values_and_holders(reinterpret_cast<instance *>(h.ptr())).begin()->value_ptr();
             return true;
         }
 
@@ -610,20 +1149,48 @@ template <> class type_caster<void> : public type_caster<void_type> {
 
     template <typename T> using cast_op_type = void*&;
     operator void *&() { return value; }
-    static PYBIND11_DESCR name() { return type_descr(_("capsule")); }
+    static constexpr auto name = _("capsule");
 private:
     void *value = nullptr;
 };
 
-template <> class type_caster<std::nullptr_t> : public type_caster<void_type> { };
+template <> class type_caster<std::nullptr_t> : public void_caster<std::nullptr_t> { };
 
 template <> class type_caster<bool> {
 public:
-    bool load(handle src, bool) {
+    bool load(handle src, bool convert) {
         if (!src) return false;
         else if (src.ptr() == Py_True) { value = true; return true; }
         else if (src.ptr() == Py_False) { value = false; return true; }
-        else return false;
+        else if (convert || !strcmp("numpy.bool_", Py_TYPE(src.ptr())->tp_name)) {
+            // (allow non-implicit conversion for numpy booleans)
+
+            Py_ssize_t res = -1;
+            if (src.is_none()) {
+                res = 0;  // None is implicitly converted to False
+            }
+            #if defined(PYPY_VERSION)
+            // On PyPy, check that "__bool__" (or "__nonzero__" on Python 2.7) attr exists
+            else if (hasattr(src, PYBIND11_BOOL_ATTR)) {
+                res = PyObject_IsTrue(src.ptr());
+            }
+            #else
+            // Alternate approach for CPython: this does the same as the above, but optimized
+            // using the CPython API so as to avoid an unneeded attribute lookup.
+            else if (auto tp_as_number = src.ptr()->ob_type->tp_as_number) {
+                if (PYBIND11_NB_BOOL(tp_as_number)) {
+                    res = (*PYBIND11_NB_BOOL(tp_as_number))(src.ptr());
+                }
+            }
+            #endif
+            if (res == 0 || res == 1) {
+                value = (bool) res;
+                return true;
+            } else {
+                PyErr_Clear();
+            }
+        }
+        return false;
     }
     static handle cast(bool src, return_value_policy /* policy */, handle /* parent */) {
         return handle(src ? Py_True : Py_False).inc_ref();
@@ -632,11 +1199,15 @@ template <> class type_caster<bool> {
 };
 
 // Helper class for UTF-{8,16,32} C++ stl strings:
-template <typename CharT, class Traits, class Allocator>
-struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_std_char_type<CharT>::value>> {
+template <typename StringType, bool IsView = false> struct string_caster {
+    using CharT = typename StringType::value_type;
+
     // Simplify life by being able to assume standard char sizes (the standard only guarantees
-    // minimums), but Python requires exact sizes
+    // minimums, but Python requires exact sizes)
     static_assert(!std::is_same<CharT, char>::value || sizeof(CharT) == 1, "Unsupported char size != 1");
+#if defined(PYBIND11_HAS_U8STRING)
+    static_assert(!std::is_same<CharT, char8_t>::value || sizeof(CharT) == 1, "Unsupported char8_t size != 1");
+#endif
     static_assert(!std::is_same<CharT, char16_t>::value || sizeof(CharT) == 2, "Unsupported char16_t size != 2");
     static_assert(!std::is_same<CharT, char32_t>::value || sizeof(CharT) == 4, "Unsupported char32_t size != 4");
     // wchar_t can be either 16 bits (Windows) or 32 (everywhere else)
@@ -644,8 +1215,6 @@ struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_s
             "Unsupported wchar_t size != 2/4");
     static constexpr size_t UTF_N = 8 * sizeof(CharT);
 
-    using StringType = std::basic_string<CharT, Traits, Allocator>;
-
     bool load(handle src, bool) {
 #if PY_MAJOR_VERSION < 3
         object temp;
@@ -655,31 +1224,41 @@ struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_s
             return false;
         } else if (!PyUnicode_Check(load_src.ptr())) {
 #if PY_MAJOR_VERSION >= 3
-            return false;
-            // The below is a guaranteed failure in Python 3 when PyUnicode_Check returns false
+            return load_bytes(load_src);
 #else
+            if (std::is_same<CharT, char>::value) {
+                return load_bytes(load_src);
+            }
+
+            // The below is a guaranteed failure in Python 3 when PyUnicode_Check returns false
             if (!PYBIND11_BYTES_CHECK(load_src.ptr()))
                 return false;
+
             temp = reinterpret_steal<object>(PyUnicode_FromObject(load_src.ptr()));
             if (!temp) { PyErr_Clear(); return false; }
             load_src = temp;
 #endif
         }
 
-        object utfNbytes = reinterpret_steal<object>(PyUnicode_AsEncodedString(
+        auto utfNbytes = reinterpret_steal<object>(PyUnicode_AsEncodedString(
             load_src.ptr(), UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr));
         if (!utfNbytes) { PyErr_Clear(); return false; }
 
-        const CharT *buffer = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
+        const auto *buffer = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
         size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
         if (UTF_N > 8) { buffer++; length--; } // Skip BOM for UTF-16/32
         value = StringType(buffer, length);
+
+        // If we're loading a string_view we need to keep the encoded Python object alive:
+        if (IsView)
+            loader_life_support::add_patient(utfNbytes);
+
         return true;
     }
 
     static handle cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {
-        const char *buffer = reinterpret_cast<const char *>(src.c_str());
-        ssize_t nbytes = ssize_t(src.size() * sizeof(CharT));
+        const char *buffer = reinterpret_cast<const char *>(src.data());
+        auto nbytes = ssize_t(src.size() * sizeof(CharT));
         handle s = decode_utfN(buffer, nbytes);
         if (!s) throw error_already_set();
         return s;
@@ -695,15 +1274,44 @@ struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_s
             UTF_N == 16 ? PyUnicode_DecodeUTF16(buffer, nbytes, nullptr, nullptr) :
                           PyUnicode_DecodeUTF32(buffer, nbytes, nullptr, nullptr);
 #else
-        // PyPy seems to have multiple problems related to PyUnicode_UTF*: the UTF8 version
-        // sometimes segfaults for unknown reasons, while the UTF16 and 32 versions require a
-        // non-const char * arguments, which is also a nuissance, so bypass the whole thing by just
-        // passing the encoding as a string value, which works properly:
+        // PyPy segfaults when on PyUnicode_DecodeUTF16 (and possibly on PyUnicode_DecodeUTF32 as well),
+        // so bypass the whole thing by just passing the encoding as a string value, which works properly:
         return PyUnicode_Decode(buffer, nbytes, UTF_N == 8 ? "utf-8" : UTF_N == 16 ? "utf-16" : "utf-32", nullptr);
 #endif
     }
+
+    // When loading into a std::string or char*, accept a bytes object as-is (i.e.
+    // without any encoding/decoding attempt).  For other C++ char sizes this is a no-op.
+    // which supports loading a unicode from a str, doesn't take this path.
+    template <typename C = CharT>
+    bool load_bytes(enable_if_t<std::is_same<C, char>::value, handle> src) {
+        if (PYBIND11_BYTES_CHECK(src.ptr())) {
+            // We were passed a Python 3 raw bytes; accept it into a std::string or char*
+            // without any encoding attempt.
+            const char *bytes = PYBIND11_BYTES_AS_STRING(src.ptr());
+            if (bytes) {
+                value = StringType(bytes, (size_t) PYBIND11_BYTES_SIZE(src.ptr()));
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    template <typename C = CharT>
+    bool load_bytes(enable_if_t<!std::is_same<C, char>::value, handle>) { return false; }
 };
 
+template <typename CharT, class Traits, class Allocator>
+struct type_caster<std::basic_string<CharT, Traits, Allocator>, enable_if_t<is_std_char_type<CharT>::value>>
+    : string_caster<std::basic_string<CharT, Traits, Allocator>> {};
+
+#ifdef PYBIND11_HAS_STRING_VIEW
+template <typename CharT, class Traits>
+struct type_caster<std::basic_string_view<CharT, Traits>, enable_if_t<is_std_char_type<CharT>::value>>
+    : string_caster<std::basic_string_view<CharT, Traits>, true> {};
+#endif
+
 // Type caster for C-style strings.  We basically use a std::string type caster, but also add the
 // ability to use None as a nullptr char* (which the string caster doesn't allow).
 template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type<CharT>::value>> {
@@ -711,6 +1319,7 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
     using StringCaster = type_caster<StringType>;
     StringCaster str_caster;
     bool none = false;
+    CharT one_char = 0;
 public:
     bool load(handle src, bool convert) {
         if (!src) return false;
@@ -738,7 +1347,7 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
     }
 
     operator CharT*() { return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str()); }
-    operator CharT() {
+    operator CharT&() {
         if (none)
             throw value_error("Cannot convert None to a character");
 
@@ -753,7 +1362,7 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
         // errors.  We also allow want to allow unicode characters U+0080 through U+00FF, as those
         // can fit into a single char value.
         if (StringCaster::UTF_N == 8 && str_len > 1 && str_len <= 4) {
-            unsigned char v0 = static_cast<unsigned char>(value[0]);
+            auto v0 = static_cast<unsigned char>(value[0]);
             size_t char0_bytes = !(v0 & 0x80) ? 1 : // low bits only: 0-127
                 (v0 & 0xE0) == 0xC0 ? 2 : // 0b110xxxxx - start of 2-byte sequence
                 (v0 & 0xF0) == 0xE0 ? 3 : // 0b1110xxxx - start of 3-byte sequence
@@ -762,7 +1371,8 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
             if (char0_bytes == str_len) {
                 // If we have a 128-255 value, we can decode it into a single char:
                 if (char0_bytes == 2 && (v0 & 0xFC) == 0xC0) { // 0x110000xx 0x10xxxxxx
-                    return static_cast<CharT>(((v0 & 3) << 6) + (static_cast<unsigned char>(value[1]) & 0x3F));
+                    one_char = static_cast<CharT>(((v0 & 3) << 6) + (static_cast<unsigned char>(value[1]) & 0x3F));
+                    return one_char;
                 }
                 // Otherwise we have a single character, but it's > U+00FF
                 throw value_error("Character code point not in range(0x100)");
@@ -773,66 +1383,29 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
         // surrogate pair with total length 2 instantly indicates a range error (but not a "your
         // string was too long" error).
         else if (StringCaster::UTF_N == 16 && str_len == 2) {
-            char16_t v0 = static_cast<char16_t>(value[0]);
-            if (v0 >= 0xD800 && v0 < 0xE000)
+            one_char = static_cast<CharT>(value[0]);
+            if (one_char >= 0xD800 && one_char < 0xE000)
                 throw value_error("Character code point not in range(0x10000)");
         }
 
         if (str_len != 1)
             throw value_error("Expected a character, but multi-character string found");
 
-        return value[0];
+        one_char = value[0];
+        return one_char;
     }
 
-    static PYBIND11_DESCR name() { return type_descr(_(PYBIND11_STRING_NAME)); }
-    template <typename _T> using cast_op_type = typename std::remove_reference<pybind11::detail::cast_op_type<_T>>::type;
+    static constexpr auto name = _(PYBIND11_STRING_NAME);
+    template <typename _T> using cast_op_type = pybind11::detail::cast_op_type<_T>;
 };
 
-template <typename T1, typename T2> class type_caster<std::pair<T1, T2>> {
-    typedef std::pair<T1, T2> type;
+// Base implementation for std::tuple and std::pair
+template <template<typename...> class Tuple, typename... Ts> class tuple_caster {
+    using type = Tuple<Ts...>;
+    static constexpr auto size = sizeof...(Ts);
+    using indices = make_index_sequence<size>;
 public:
-    bool load(handle src, bool convert) {
-        if (!isinstance<sequence>(src))
-            return false;
-        const auto seq = reinterpret_borrow<sequence>(src);
-        if (seq.size() != 2)
-            return false;
-        return first.load(seq[0], convert) && second.load(seq[1], convert);
-    }
-
-    static handle cast(const type &src, return_value_policy policy, handle parent) {
-        auto o1 = reinterpret_steal<object>(make_caster<T1>::cast(src.first, policy, parent));
-        auto o2 = reinterpret_steal<object>(make_caster<T2>::cast(src.second, policy, parent));
-        if (!o1 || !o2)
-            return handle();
-        tuple result(2);
-        PyTuple_SET_ITEM(result.ptr(), 0, o1.release().ptr());
-        PyTuple_SET_ITEM(result.ptr(), 1, o2.release().ptr());
-        return result.release();
-    }
 
-    static PYBIND11_DESCR name() {
-        return type_descr(
-            _("Tuple[") + make_caster<T1>::name() + _(", ") + make_caster<T2>::name() + _("]")
-        );
-    }
-
-    template <typename T> using cast_op_type = type;
-
-    operator type() {
-        return type(cast_op<T1>(first), cast_op<T2>(second));
-    }
-protected:
-    make_caster<T1> first;
-    make_caster<T2> second;
-};
-
-template <typename... Tuple> class type_caster<std::tuple<Tuple...>> {
-    using type = std::tuple<Tuple...>;
-    using indices = make_index_sequence<sizeof...(Tuple)>;
-    static constexpr auto size = sizeof...(Tuple);
-
-public:
     bool load(handle src, bool convert) {
         if (!isinstance<sequence>(src))
             return false;
@@ -842,40 +1415,55 @@ template <typename... Tuple> class type_caster<std::tuple<Tuple...>> {
         return load_impl(seq, convert, indices{});
     }
 
-    static handle cast(const type &src, return_value_policy policy, handle parent) {
-        return cast_impl(src, policy, parent, indices{});
+    template <typename T>
+    static handle cast(T &&src, return_value_policy policy, handle parent) {
+        return cast_impl(std::forward<T>(src), policy, parent, indices{});
     }
 
-    static PYBIND11_DESCR name() {
-        return type_descr(_("Tuple[") + detail::concat(make_caster<Tuple>::name()...) + _("]"));
+    // copied from the PYBIND11_TYPE_CASTER macro
+    template <typename T>
+    static handle cast(T *src, return_value_policy policy, handle parent) {
+        if (!src) return none().release();
+        if (policy == return_value_policy::take_ownership) {
+            auto h = cast(std::move(*src), policy, parent); delete src; return h;
+        } else {
+            return cast(*src, policy, parent);
+        }
     }
 
+    static constexpr auto name = _("Tuple[") + concat(make_caster<Ts>::name...) + _("]");
+
     template <typename T> using cast_op_type = type;
 
-    operator type() { return implicit_cast(indices{}); }
+    operator type() & { return implicit_cast(indices{}); }
+    operator type() && { return std::move(*this).implicit_cast(indices{}); }
 
 protected:
     template <size_t... Is>
-    type implicit_cast(index_sequence<Is...>) { return type(cast_op<Tuple>(std::get<Is>(value))...); }
+    type implicit_cast(index_sequence<Is...>) & { return type(cast_op<Ts>(std::get<Is>(subcasters))...); }
+    template <size_t... Is>
+    type implicit_cast(index_sequence<Is...>) && { return type(cast_op<Ts>(std::move(std::get<Is>(subcasters)))...); }
 
     static constexpr bool load_impl(const sequence &, bool, index_sequence<>) { return true; }
 
     template <size_t... Is>
     bool load_impl(const sequence &seq, bool convert, index_sequence<Is...>) {
-        for (bool r : {std::get<Is>(value).load(seq[Is], convert)...})
+#ifdef __cpp_fold_expressions
+        if ((... || !std::get<Is>(subcasters).load(seq[Is], convert)))
+            return false;
+#else
+        for (bool r : {std::get<Is>(subcasters).load(seq[Is], convert)...})
             if (!r)
                 return false;
+#endif
         return true;
     }
 
-    static handle cast_impl(const type &, return_value_policy, handle,
-                            index_sequence<>) { return tuple().release(); }
-
     /* Implementation: Convert a C++ tuple into a Python tuple */
-    template <size_t... Is>
-    static handle cast_impl(const type &src, return_value_policy policy, handle parent, index_sequence<Is...>) {
-        std::array<object, size> entries {{
-            reinterpret_steal<object>(make_caster<Tuple>::cast(std::get<Is>(src), policy, parent))...
+    template <typename T, size_t... Is>
+    static handle cast_impl(T &&src, return_value_policy policy, handle parent, index_sequence<Is...>) {
+        std::array<object, size> entries{{
+            reinterpret_steal<object>(make_caster<Ts>::cast(std::get<Is>(std::forward<T>(src)), policy, parent))...
         }};
         for (const auto &entry: entries)
             if (!entry)
@@ -887,9 +1475,15 @@ template <typename... Tuple> class type_caster<std::tuple<Tuple...>> {
         return result.release();
     }
 
-    std::tuple<make_caster<Tuple>...> value;
+    Tuple<make_caster<Ts>...> subcasters;
 };
 
+template <typename T1, typename T2> class type_caster<std::pair<T1, T2>>
+    : public tuple_caster<std::pair, T1, T2> {};
+
+template <typename... Ts> class type_caster<std::tuple<Ts...>>
+    : public tuple_caster<std::tuple, Ts...> {};
+
 /// Helper class which abstracts away certain actions. Users can provide specializations for
 /// custom holders, but it's only necessary if the type has a non-standard interface.
 template <typename T>
@@ -902,68 +1496,40 @@ template <typename type, typename holder_type>
 struct copyable_holder_caster : public type_caster_base<type> {
 public:
     using base = type_caster_base<type>;
+    static_assert(std::is_base_of<base, type_caster<type>>::value,
+            "Holder classes are only supported for custom types");
     using base::base;
     using base::cast;
     using base::typeinfo;
     using base::value;
-    using base::temp;
 
-    PYBIND11_NOINLINE bool load(handle src, bool convert) {
-        return load(src, convert, Py_TYPE(src.ptr()));
+    bool load(handle src, bool convert) {
+        return base::template load_impl<copyable_holder_caster<type, holder_type>>(src, convert);
     }
 
-    bool load(handle src, bool convert, PyTypeObject *tobj) {
-        if (!src || !typeinfo)
-            return false;
-        if (src.is_none()) {
-            value = nullptr;
-            return true;
-        }
+    explicit operator type*() { return this->value; }
+    // static_cast works around compiler error with MSVC 17 and CUDA 10.2
+    // see issue #2180
+    explicit operator type&() { return *(static_cast<type *>(this->value)); }
+    explicit operator holder_type*() { return std::addressof(holder); }
+    explicit operator holder_type&() { return holder; }
 
+    static handle cast(const holder_type &src, return_value_policy, handle) {
+        const auto *ptr = holder_helper<holder_type>::get(src);
+        return type_caster_base<type>::cast_holder(ptr, &src);
+    }
+
+protected:
+    friend class type_caster_generic;
+    void check_holder_compat() {
         if (typeinfo->default_holder)
             throw cast_error("Unable to load a custom holder type from a default-holder instance");
-
-        if (typeinfo->simple_type) { /* Case 1: no multiple inheritance etc. involved */
-            /* Check if we can safely perform a reinterpret-style cast */
-            if (PyType_IsSubtype(tobj, typeinfo->type))
-                return load_value_and_holder(src);
-        } else { /* Case 2: multiple inheritance */
-            /* Check if we can safely perform a reinterpret-style cast */
-            if (tobj == typeinfo->type)
-                return load_value_and_holder(src);
-
-            /* If this is a python class, also check the parents recursively */
-            auto const &type_dict = get_internals().registered_types_py;
-            bool new_style_class = PyType_Check((PyObject *) tobj);
-            if (type_dict.find(tobj) == type_dict.end() && new_style_class && tobj->tp_bases) {
-                auto parents = reinterpret_borrow<tuple>(tobj->tp_bases);
-                for (handle parent : parents) {
-                    bool result = load(src, convert, (PyTypeObject *) parent.ptr());
-                    if (result)
-                        return true;
-                }
-            }
-
-            if (try_implicit_casts(src, convert))
-                return true;
-        }
-
-        if (convert) {
-            for (auto &converter : typeinfo->implicit_conversions) {
-                temp = reinterpret_steal<object>(converter(src.ptr(), typeinfo->type));
-                if (load(temp, false))
-                    return true;
-            }
-        }
-
-        return false;
     }
 
-    bool load_value_and_holder(handle src) {
-        auto inst = (instance<type, holder_type> *) src.ptr();
-        value = (void *) inst->value;
-        if (inst->holder_constructed) {
-            holder = inst->holder;
+    bool load_value(value_and_holder &&v_h) {
+        if (v_h.holder_constructed()) {
+            value = v_h.value_ptr();
+            holder = v_h.template holder<holder_type>();
             return true;
         } else {
             throw cast_error("Unable to cast from non-held to held instance (T& to Holder<T>) "
@@ -991,24 +1557,9 @@ struct copyable_holder_caster : public type_caster_base<type> {
         return false;
     }
 
-    explicit operator type*() { return this->value; }
-    explicit operator type&() { return *(this->value); }
-    explicit operator holder_type*() { return &holder; }
-
-    // Workaround for Intel compiler bug
-    // see pybind11 issue 94
-    #if defined(__ICC) || defined(__INTEL_COMPILER)
-    operator holder_type&() { return holder; }
-    #else
-    explicit operator holder_type&() { return holder; }
-    #endif
+    static bool try_direct_conversions(handle) { return false; }
 
-    static handle cast(const holder_type &src, return_value_policy, handle) {
-        const auto *ptr = holder_helper<holder_type>::get(src);
-        return type_caster_base<type>::cast_holder(ptr, &src);
-    }
 
-protected:
     holder_type holder;
 };
 
@@ -1018,11 +1569,14 @@ class type_caster<std::shared_ptr<T>> : public copyable_holder_caster<T, std::sh
 
 template <typename type, typename holder_type>
 struct move_only_holder_caster {
+    static_assert(std::is_base_of<type_caster_base<type>, type_caster<type>>::value,
+            "Holder classes are only supported for custom types");
+
     static handle cast(holder_type &&src, return_value_policy, handle) {
         auto *ptr = holder_helper<holder_type>::get(src);
-        return type_caster_base<type>::cast_holder(ptr, &src);
+        return type_caster_base<type>::cast_holder(ptr, std::addressof(src));
     }
-    static PYBIND11_DESCR name() { return type_caster_base<type>::name(); }
+    static constexpr auto name = type_caster_base<type>::name;
 };
 
 template <typename type, typename deleter>
@@ -1030,7 +1584,7 @@ class type_caster<std::unique_ptr<type, deleter>>
     : public move_only_holder_caster<type, std::unique_ptr<type, deleter>> { };
 
 template <typename type, typename holder_type>
-using type_caster_holder = conditional_t<std::is_copy_constructible<holder_type>::value,
+using type_caster_holder = conditional_t<is_copy_constructible<holder_type>::value,
                                          copyable_holder_caster<type, holder_type>,
                                          move_only_holder_caster<type, holder_type>>;
 
@@ -1053,10 +1607,14 @@ template <typename base, typename holder> struct is_holder_type :
 template <typename base, typename deleter> struct is_holder_type<base, std::unique_ptr<base, deleter>> :
     std::true_type {};
 
-template <typename T> struct handle_type_name { static PYBIND11_DESCR name() { return _<T>(); } };
-template <> struct handle_type_name<bytes> { static PYBIND11_DESCR name() { return _(PYBIND11_BYTES_NAME); } };
-template <> struct handle_type_name<args> { static PYBIND11_DESCR name() { return _("*args"); } };
-template <> struct handle_type_name<kwargs> { static PYBIND11_DESCR name() { return _("**kwargs"); } };
+template <typename T> struct handle_type_name { static constexpr auto name = _<T>(); };
+template <> struct handle_type_name<bytes> { static constexpr auto name = _(PYBIND11_BYTES_NAME); };
+template <> struct handle_type_name<int_> { static constexpr auto name = _("int"); };
+template <> struct handle_type_name<iterable> { static constexpr auto name = _("Iterable"); };
+template <> struct handle_type_name<iterator> { static constexpr auto name = _("Iterator"); };
+template <> struct handle_type_name<none> { static constexpr auto name = _("None"); };
+template <> struct handle_type_name<args> { static constexpr auto name = _("*args"); };
+template <> struct handle_type_name<kwargs> { static constexpr auto name = _("**kwargs"); };
 
 template <typename type>
 struct pyobject_caster {
@@ -1074,7 +1632,7 @@ struct pyobject_caster {
     static handle cast(const handle &src, return_value_policy /* policy */, handle /* parent */) {
         return src.inc_ref();
     }
-    PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name());
+    PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name);
 };
 
 template <typename T>
@@ -1095,7 +1653,7 @@ template <typename T> using move_is_plain_type = satisfies_none_of<T,
 template <typename T, typename SFINAE = void> struct move_always : std::false_type {};
 template <typename T> struct move_always<T, enable_if_t<all_of<
     move_is_plain_type<T>,
-    negation<std::is_copy_constructible<T>>,
+    negation<is_copy_constructible<T>>,
     std::is_move_constructible<T>,
     std::is_same<decltype(std::declval<make_caster<T>>().operator T&()), T&>
 >::value>> : std::true_type {};
@@ -1114,17 +1672,23 @@ template <typename T> using move_never = none_of<move_always<T>, move_if_unrefer
 // everything else returns a reference/pointer to a local variable.
 template <typename type> using cast_is_temporary_value_reference = bool_constant<
     (std::is_reference<type>::value || std::is_pointer<type>::value) &&
-    !std::is_base_of<type_caster_generic, make_caster<type>>::value
+    !std::is_base_of<type_caster_generic, make_caster<type>>::value &&
+    !std::is_same<intrinsic_t<type>, void>::value
 >;
 
 // When a value returned from a C++ function is being cast back to Python, we almost always want to
 // force `policy = move`, regardless of the return value policy the function/method was declared
-// with.  Some classes (most notably Eigen::Ref and related) need to avoid this, and so can do so by
-// specializing this struct.
+// with.
 template <typename Return, typename SFINAE = void> struct return_value_policy_override {
+    static return_value_policy policy(return_value_policy p) { return p; }
+};
+
+template <typename Return> struct return_value_policy_override<Return,
+        detail::enable_if_t<std::is_base_of<type_caster_generic, make_caster<Return>>::value, void>> {
     static return_value_policy policy(return_value_policy p) {
-        return !std::is_lvalue_reference<Return>::value && !std::is_pointer<Return>::value
-            ? return_value_policy::move : p;
+        return !std::is_lvalue_reference<Return>::value &&
+               !std::is_pointer<Return>::value
+                   ? return_value_policy::move : p;
     }
 };
 
@@ -1135,7 +1699,7 @@ template <typename T, typename SFINAE> type_caster<T, SFINAE> &load_type(type_ca
         throw cast_error("Unable to cast Python instance to C++ type (compile in debug mode for details)");
 #else
         throw cast_error("Unable to cast Python instance of type " +
-            (std::string) str(handle.get_type()) + " to C++ type '" + type_id<T>() + "''");
+            (std::string) str(type::handle_of(handle)) + " to C++ type '" + type_id<T>() + "'");
 #endif
     }
     return conv;
@@ -1147,7 +1711,7 @@ template <typename T> make_caster<T> load_type(const handle &handle) {
     return conv;
 }
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 // pytype -> C++ type
 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
@@ -1164,13 +1728,16 @@ T cast(const handle &handle) { return T(reinterpret_borrow<object>(handle)); }
 
 // C++ type -> py::object
 template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> = 0>
-object cast(const T &value, return_value_policy policy = return_value_policy::automatic_reference,
+object cast(T &&value, return_value_policy policy = return_value_policy::automatic_reference,
             handle parent = handle()) {
+    using no_ref_T = typename std::remove_reference<T>::type;
     if (policy == return_value_policy::automatic)
-        policy = std::is_pointer<T>::value ? return_value_policy::take_ownership : return_value_policy::copy;
+        policy = std::is_pointer<no_ref_T>::value ? return_value_policy::take_ownership :
+                 std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
     else if (policy == return_value_policy::automatic_reference)
-        policy = std::is_pointer<T>::value ? return_value_policy::reference : return_value_policy::copy;
-    return reinterpret_steal<object>(detail::make_caster<T>::cast(value, policy, parent));
+        policy = std::is_pointer<no_ref_T>::value ? return_value_policy::reference :
+                 std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
+    return reinterpret_steal<object>(detail::make_caster<T>::cast(std::forward<T>(value), policy, parent));
 }
 
 template <typename T> T handle::cast() const { return pybind11::cast<T>(*this); }
@@ -1183,7 +1750,7 @@ detail::enable_if_t<!detail::move_never<T>::value, T> move(object &&obj) {
         throw cast_error("Unable to cast Python instance to C++ rvalue: instance has multiple references"
             " (compile in debug mode for details)");
 #else
-        throw cast_error("Unable to move from Python " + (std::string) str(obj.get_type()) +
+        throw cast_error("Unable to move from Python " + (std::string) str(type::handle_of(obj)) +
                 " instance to C++ " + type_id<T>() + " instance: instance has multiple references");
 #endif
 
@@ -1192,7 +1759,7 @@ detail::enable_if_t<!detail::move_never<T>::value, T> move(object &&obj) {
     return ret;
 }
 
-// Calling cast() on an rvalue calls pybind::cast with the object rvalue, which does:
+// Calling cast() on an rvalue calls pybind11::cast with the object rvalue, which does:
 // - If we have to move (because T has no copy constructor), do it.  This will fail if the moved
 //   object has multiple references, but trying to copy will fail to compile.
 // - If both movable and copyable, check ref count: if 1, move; otherwise copy
@@ -1215,22 +1782,22 @@ template <typename T> T object::cast() && { return pybind11::cast<T>(std::move(*
 template <> inline void object::cast() const & { return; }
 template <> inline void object::cast() && { return; }
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 // Declared in pytypes.h:
 template <typename T, enable_if_t<!is_pyobject<T>::value, int>>
 object object_or_cast(T &&o) { return pybind11::cast(std::forward<T>(o)); }
 
-struct overload_unused {}; // Placeholder type for the unneeded (and dead code) static variable in the OVERLOAD_INT macro
-template <typename ret_type> using overload_caster_t = conditional_t<
-    cast_is_temporary_value_reference<ret_type>::value, make_caster<ret_type>, overload_unused>;
+struct override_unused {}; // Placeholder type for the unneeded (and dead code) static variable in the PYBIND11_OVERRIDE_OVERRIDE macro
+template <typename ret_type> using override_caster_t = conditional_t<
+    cast_is_temporary_value_reference<ret_type>::value, make_caster<ret_type>, override_unused>;
 
 // Trampoline use: for reference/pointer types to value-converted values, we do a value cast, then
 // store the result in the given variable.  For other types, this is a no-op.
 template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&o, make_caster<T> &caster) {
     return cast_op<T>(load_type(caster, o));
 }
-template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&, overload_unused &) {
+template <typename T> enable_if_t<!cast_is_temporary_value_reference<T>::value, T> cast_ref(object &&, override_unused &) {
     pybind11_fail("Internal error: cast_ref fallback invoked"); }
 
 // Trampoline use: Having a pybind11::cast with an invalid reference type is going to static_assert, even
@@ -1242,22 +1809,26 @@ template <typename T> enable_if_t<cast_is_temporary_value_reference<T>::value, T
     pybind11_fail("Internal error: cast_safe fallback invoked"); }
 template <> inline void cast_safe<void>(object &&) {}
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
+
+template <return_value_policy policy = return_value_policy::automatic_reference>
+tuple make_tuple() { return tuple(0); }
 
 template <return_value_policy policy = return_value_policy::automatic_reference,
           typename... Args> tuple make_tuple(Args&&... args_) {
-    const size_t size = sizeof...(Args);
+    constexpr size_t size = sizeof...(Args);
     std::array<object, size> args {
         { reinterpret_steal<object>(detail::make_caster<Args>::cast(
             std::forward<Args>(args_), policy, nullptr))... }
     };
-    for (auto &arg_value : args) {
-        if (!arg_value) {
+    for (size_t i = 0; i < args.size(); i++) {
+        if (!args[i]) {
 #if defined(NDEBUG)
             throw cast_error("make_tuple(): unable to convert arguments to Python object (compile in debug mode for details)");
 #else
-            throw cast_error("make_tuple(): unable to convert arguments of types '" +
-                (std::string) type_id<std::tuple<Args...>>() + "' to Python object");
+            std::array<std::string, size> argtypes { {type_id<Args>()...} };
+            throw cast_error("make_tuple(): unable to convert argument of type '" +
+                argtypes[i] + "' to Python object");
 #endif
         }
     }
@@ -1272,14 +1843,17 @@ template <return_value_policy policy = return_value_policy::automatic_reference,
 /// Annotation for arguments
 struct arg {
     /// Constructs an argument with the name of the argument; if null or omitted, this is a positional argument.
-    constexpr explicit arg(const char *name = nullptr) : name(name), flag_noconvert(false) { }
+    constexpr explicit arg(const char *name = nullptr) : name(name), flag_noconvert(false), flag_none(true) { }
     /// Assign a value to this argument
     template <typename T> arg_v operator=(T &&value) const;
     /// Indicate that the type should not be converted in the type caster
     arg &noconvert(bool flag = true) { flag_noconvert = flag; return *this; }
+    /// Indicates that the argument should/shouldn't allow None (e.g. for nullable pointer args)
+    arg &none(bool flag = true) { flag_none = flag; return *this; }
 
     const char *name; ///< If non-null, this is a named kwargs argument
     bool flag_noconvert : 1; ///< If set, do not allow conversion (requires a supporting type caster!)
+    bool flag_none : 1; ///< If set (the default), allow None to be passed to this argument
 };
 
 /// \ingroup annotations
@@ -1312,6 +1886,9 @@ struct arg_v : arg {
     /// Same as `arg::noconvert()`, but returns *this as arg_v&, not arg&
     arg_v &noconvert(bool flag = true) { arg::noconvert(flag); return *this; }
 
+    /// Same as `arg::nonone()`, but returns *this as arg_v&, not arg&
+    arg_v &none(bool flag = true) { arg::none(flag); return *this; }
+
     /// The default value
     object value;
     /// The (optional) description of the default value
@@ -1322,6 +1899,16 @@ struct arg_v : arg {
 #endif
 };
 
+/// \ingroup annotations
+/// Annotation indicating that all following arguments are keyword-only; the is the equivalent of an
+/// unnamed '*' argument (in Python 3)
+struct kw_only {};
+
+/// \ingroup annotations
+/// Annotation indicating that all previous arguments are positional-only; the is the equivalent of an
+/// unnamed '/' argument (in Python 3.8)
+struct pos_only {};
+
 template <typename T>
 arg_v arg::operator=(T &&value) const { return {std::move(*this), std::forward<T>(value)}; }
 
@@ -1333,16 +1920,16 @@ inline namespace literals {
     String literal version of `arg`
  \endrst */
 constexpr arg operator"" _a(const char *name, size_t) { return arg(name); }
-}
+} // namespace literals
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
-// forward declaration
+// forward declaration (definition in attr.h)
 struct function_record;
 
 /// Internal data associated with a single function call
 struct function_call {
-    function_call(function_record &f, handle p); // Implementation in attr.h
+    function_call(const function_record &f, handle p); // Implementation in attr.h
 
     /// The function data:
     const function_record &func;
@@ -1353,8 +1940,15 @@ struct function_call {
     /// The `convert` value the arguments should be loaded with
     std::vector<bool> args_convert;
 
+    /// Extra references for the optional `py::args` and/or `py::kwargs` arguments (which, if
+    /// present, are also in `args` but without a reference).
+    object args_ref, kwargs_ref;
+
     /// The parent, if any
     handle parent;
+
+    /// If this is a call to an initializer, this argument contains `self`
+    handle init_self;
 };
 
 
@@ -1377,20 +1971,20 @@ class argument_loader {
     static constexpr bool has_kwargs = kwargs_pos < 0;
     static constexpr bool has_args = args_pos < 0;
 
-    static PYBIND11_DESCR arg_names() { return detail::concat(make_caster<Args>::name()...); }
+    static constexpr auto arg_names = concat(type_descr(make_caster<Args>::name)...);
 
     bool load_args(function_call &call) {
         return load_impl_sequence(call, indices{});
     }
 
-    template <typename Return, typename Func>
-    enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) {
-        return call_impl<Return>(std::forward<Func>(f), indices{});
+    template <typename Return, typename Guard, typename Func>
+    enable_if_t<!std::is_void<Return>::value, Return> call(Func &&f) && {
+        return std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
     }
 
-    template <typename Return, typename Func>
-    enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) {
-        call_impl<Return>(std::forward<Func>(f), indices{});
+    template <typename Return, typename Guard, typename Func>
+    enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) && {
+        std::move(*this).template call_impl<Return>(std::forward<Func>(f), indices{}, Guard{});
         return void_type();
     }
 
@@ -1400,18 +1994,23 @@ class argument_loader {
 
     template <size_t... Is>
     bool load_impl_sequence(function_call &call, index_sequence<Is...>) {
-        for (bool r : {std::get<Is>(value).load(call.args[Is], call.args_convert[Is])...})
+#ifdef __cpp_fold_expressions
+        if ((... || !std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])))
+            return false;
+#else
+        for (bool r : {std::get<Is>(argcasters).load(call.args[Is], call.args_convert[Is])...})
             if (!r)
                 return false;
+#endif
         return true;
     }
 
-    template <typename Return, typename Func, size_t... Is>
-    Return call_impl(Func &&f, index_sequence<Is...>) {
-        return std::forward<Func>(f)(cast_op<Args>(std::get<Is>(value))...);
+    template <typename Return, typename Func, size_t... Is, typename Guard>
+    Return call_impl(Func &&f, index_sequence<Is...>, Guard &&) && {
+        return std::forward<Func>(f)(cast_op<Args>(std::move(std::get<Is>(argcasters)))...);
     }
 
-    std::tuple<make_caster<Args>...> value;
+    std::tuple<make_caster<Args>...> argcasters;
 };
 
 /// Helper class which collects only positional arguments for a Python function call.
@@ -1484,7 +2083,7 @@ class unpacking_collector {
     }
 
     void process(list &args_list, detail::args_proxy ap) {
-        for (const auto &a : ap)
+        for (auto a : ap)
             args_list.append(a);
     }
 
@@ -1516,7 +2115,7 @@ class unpacking_collector {
     void process(list &/*args_list*/, detail::kwargs_proxy kp) {
         if (!kp)
             return;
-        for (const auto &k : reinterpret_borrow<dict>(kp)) {
+        for (auto k : reinterpret_borrow<dict>(kp)) {
             if (m_kwargs.contains(k.first)) {
 #if defined(NDEBUG)
                 multiple_values_error();
@@ -1594,11 +2193,27 @@ object object_api<Derived>::call(Args &&...args) const {
     return operator()<policy>(std::forward<Args>(args)...);
 }
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
+
 
-#define PYBIND11_MAKE_OPAQUE(Type) \
+template<typename T>
+handle type::handle_of() {
+   static_assert(
+      std::is_base_of<detail::type_caster_generic, detail::make_caster<T>>::value,
+      "py::type::of<T> only supports the case where T is a registered C++ types."
+    );
+
+    return detail::get_type_handle(typeid(T), true);
+}
+
+
+#define PYBIND11_MAKE_OPAQUE(...) \
     namespace pybind11 { namespace detail { \
-        template<> class type_caster<Type> : public type_caster_base<Type> { }; \
+        template<> class type_caster<__VA_ARGS__> : public type_caster_base<__VA_ARGS__> { }; \
     }}
 
-NAMESPACE_END(pybind11)
+/// Lets you pass a type containing a `,` through a macro parameter without needing a separate
+/// typedef, e.g.: `PYBIND11_OVERRIDE(PYBIND11_TYPE(ReturnType<A, B>), PYBIND11_TYPE(Parent<C, D>), f, arg)`
+#define PYBIND11_TYPE(...) __VA_ARGS__
+
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/chrono.h b/libs/pybind/pybind11/chrono.h
index 8a41d08b0c..c3681102da 100644
--- a/libs/pybind/pybind11/chrono.h
+++ b/libs/pybind/pybind11/chrono.h
@@ -27,15 +27,15 @@
 #define PyDateTime_DELTA_GET_MICROSECONDS(o) (((PyDateTime_Delta*)o)->microseconds)
 #endif
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 template <typename type> class duration_caster {
 public:
-    typedef typename type::rep rep;
-    typedef typename type::period period;
+    using rep = typename type::rep;
+    using period = typename type::period;
 
-    typedef std::chrono::duration<uint_fast32_t, std::ratio<86400>> days;
+    using days = std::chrono::duration<uint_fast32_t, std::ratio<86400>>;
 
     bool load(handle src, bool) {
         using namespace std::chrono;
@@ -98,7 +98,7 @@ template <typename type> class duration_caster {
 // This is for casting times on the system clock into datetime.datetime instances
 template <typename Duration> class type_caster<std::chrono::time_point<std::chrono::system_clock, Duration>> {
 public:
-    typedef std::chrono::time_point<std::chrono::system_clock, Duration> type;
+    using type = std::chrono::time_point<std::chrono::system_clock, Duration>;
     bool load(handle src, bool) {
         using namespace std::chrono;
 
@@ -106,8 +106,11 @@ template <typename Duration> class type_caster<std::chrono::time_point<std::chro
         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         if (!src) return false;
+
+        std::tm cal;
+        microseconds msecs;
+
         if (PyDateTime_Check(src.ptr())) {
-            std::tm cal;
             cal.tm_sec   = PyDateTime_DATE_GET_SECOND(src.ptr());
             cal.tm_min   = PyDateTime_DATE_GET_MINUTE(src.ptr());
             cal.tm_hour  = PyDateTime_DATE_GET_HOUR(src.ptr());
@@ -115,11 +118,30 @@ template <typename Duration> class type_caster<std::chrono::time_point<std::chro
             cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
             cal.tm_year  = PyDateTime_GET_YEAR(src.ptr()) - 1900;
             cal.tm_isdst = -1;
-
-            value = system_clock::from_time_t(std::mktime(&cal)) + microseconds(PyDateTime_DATE_GET_MICROSECOND(src.ptr()));
-            return true;
+            msecs        = microseconds(PyDateTime_DATE_GET_MICROSECOND(src.ptr()));
+        } else if (PyDate_Check(src.ptr())) {
+            cal.tm_sec   = 0;
+            cal.tm_min   = 0;
+            cal.tm_hour  = 0;
+            cal.tm_mday  = PyDateTime_GET_DAY(src.ptr());
+            cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
+            cal.tm_year  = PyDateTime_GET_YEAR(src.ptr()) - 1900;
+            cal.tm_isdst = -1;
+            msecs        = microseconds(0);
+        } else if (PyTime_Check(src.ptr())) {
+            cal.tm_sec   = PyDateTime_TIME_GET_SECOND(src.ptr());
+            cal.tm_min   = PyDateTime_TIME_GET_MINUTE(src.ptr());
+            cal.tm_hour  = PyDateTime_TIME_GET_HOUR(src.ptr());
+            cal.tm_mday  = 1;   // This date (day, month, year) = (1, 0, 70)
+            cal.tm_mon   = 0;   // represents 1-Jan-1970, which is the first
+            cal.tm_year  = 70;  // earliest available date for Python's datetime
+            cal.tm_isdst = -1;
+            msecs        = microseconds(PyDateTime_TIME_GET_MICROSECOND(src.ptr()));
         }
         else return false;
+
+        value = time_point_cast<Duration>(system_clock::from_time_t(std::mktime(&cal)) + msecs);
+        return true;
     }
 
     static handle cast(const std::chrono::time_point<std::chrono::system_clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
@@ -128,21 +150,28 @@ template <typename Duration> class type_caster<std::chrono::time_point<std::chro
         // Lazy initialise the PyDateTime import
         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
-        std::time_t tt = system_clock::to_time_t(src);
+        // Get out microseconds, and make sure they are positive, to avoid bug in eastern hemisphere time zones
+        // (cfr. https://github.com/pybind/pybind11/issues/2417)
+        using us_t = duration<int, std::micro>;
+        auto us = duration_cast<us_t>(src.time_since_epoch() % seconds(1));
+        if (us.count() < 0)
+            us += seconds(1);
+
+        // Subtract microseconds BEFORE `system_clock::to_time_t`, because:
+        // > If std::time_t has lower precision, it is implementation-defined whether the value is rounded or truncated.
+        // (https://en.cppreference.com/w/cpp/chrono/system_clock/to_time_t)
+        std::time_t tt = system_clock::to_time_t(time_point_cast<system_clock::duration>(src - us));
         // this function uses static memory so it's best to copy it out asap just in case
         // otherwise other code that is using localtime may break this (not just python code)
         std::tm localtime = *std::localtime(&tt);
 
-        // Declare these special duration types so the conversions happen with the correct primitive types (int)
-        using us_t = duration<int, std::micro>;
-
         return PyDateTime_FromDateAndTime(localtime.tm_year + 1900,
                                           localtime.tm_mon + 1,
                                           localtime.tm_mday,
                                           localtime.tm_hour,
                                           localtime.tm_min,
                                           localtime.tm_sec,
-                                          (duration_cast<us_t>(src.time_since_epoch() % seconds(1))).count());
+                                          us.count());
     }
     PYBIND11_TYPE_CASTER(type, _("datetime.datetime"));
 };
@@ -158,5 +187,5 @@ template <typename Rep, typename Period> class type_caster<std::chrono::duration
 : public duration_caster<std::chrono::duration<Rep, Period>> {
 };
 
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/class_support.h b/libs/pybind/pybind11/class_support.h
deleted file mode 100644
index 992703ff32..0000000000
--- a/libs/pybind/pybind11/class_support.h
+++ /dev/null
@@ -1,504 +0,0 @@
-/*
-    pybind11/class_support.h: Python C API implementation details for py::class_
-
-    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
-
-    All rights reserved. Use of this source code is governed by a
-    BSD-style license that can be found in the LICENSE file.
-*/
-
-#pragma once
-
-#include "attr.h"
-
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
-
-#if !defined(PYPY_VERSION)
-
-/// `pybind11_static_property.__get__()`: Always pass the class instead of the instance.
-extern "C" inline PyObject *pybind11_static_get(PyObject *self, PyObject * /*ob*/, PyObject *cls) {
-    return PyProperty_Type.tp_descr_get(self, cls, cls);
-}
-
-/// `pybind11_static_property.__set__()`: Just like the above `__get__()`.
-extern "C" inline int pybind11_static_set(PyObject *self, PyObject *obj, PyObject *value) {
-    PyObject *cls = PyType_Check(obj) ? obj : (PyObject *) Py_TYPE(obj);
-    return PyProperty_Type.tp_descr_set(self, cls, value);
-}
-
-/** A `static_property` is the same as a `property` but the `__get__()` and `__set__()`
-    methods are modified to always use the object type instead of a concrete instance.
-    Return value: New reference. */
-inline PyTypeObject *make_static_property_type() {
-    constexpr auto *name = "pybind11_static_property";
-    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
-
-    /* Danger zone: from now (and until PyType_Ready), make sure to
-       issue no Python C API calls which could potentially invoke the
-       garbage collector (the GC will call type_traverse(), which will in
-       turn find the newly constructed type in an invalid state) */
-    auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
-    if (!heap_type)
-        pybind11_fail("make_static_property_type(): error allocating type!");
-
-    heap_type->ht_name = name_obj.inc_ref().ptr();
-#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
-    heap_type->ht_qualname = name_obj.inc_ref().ptr();
-#endif
-
-    auto type = &heap_type->ht_type;
-    type->tp_name = name;
-    type->tp_base = &PyProperty_Type;
-    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
-    type->tp_descr_get = pybind11_static_get;
-    type->tp_descr_set = pybind11_static_set;
-
-    if (PyType_Ready(type) < 0)
-        pybind11_fail("make_static_property_type(): failure in PyType_Ready()!");
-
-    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
-
-    return type;
-}
-
-#else // PYPY
-
-/** PyPy has some issues with the above C API, so we evaluate Python code instead.
-    This function will only be called once so performance isn't really a concern.
-    Return value: New reference. */
-inline PyTypeObject *make_static_property_type() {
-    auto d = dict();
-    PyObject *result = PyRun_String(R"(\
-        class pybind11_static_property(property):
-            def __get__(self, obj, cls):
-                return property.__get__(self, cls, cls)
-
-            def __set__(self, obj, value):
-                cls = obj if isinstance(obj, type) else type(obj)
-                property.__set__(self, cls, value)
-        )", Py_file_input, d.ptr(), d.ptr()
-    );
-    if (result == nullptr)
-        throw error_already_set();
-    Py_DECREF(result);
-    return (PyTypeObject *) d["pybind11_static_property"].cast<object>().release().ptr();
-}
-
-#endif // PYPY
-
-/** Inheriting from multiple C++ types in Python is not supported -- set an error instead.
-    A Python definition (`class C(A, B): pass`) will call `tp_new` so we check for multiple
-    C++ bases here. On the other hand, C++ type definitions (`py::class_<C, A, B>(m, "C")`)
-    don't not use `tp_new` and will not trigger this error. */
-extern "C" inline PyObject *pybind11_meta_new(PyTypeObject *metaclass, PyObject *args,
-                                              PyObject *kwargs) {
-    PyObject *bases = PyTuple_GetItem(args, 1); // arguments: (name, bases, dict)
-    if (!bases)
-        return nullptr;
-
-    auto &internals = get_internals();
-    auto num_cpp_bases = 0;
-    for (auto base : reinterpret_borrow<tuple>(bases)) {
-        auto base_type = (PyTypeObject *) base.ptr();
-        auto instance_size = static_cast<size_t>(base_type->tp_basicsize);
-        if (PyObject_IsSubclass(base.ptr(), internals.get_base(instance_size)))
-            ++num_cpp_bases;
-    }
-
-    if (num_cpp_bases > 1) {
-        PyErr_SetString(PyExc_TypeError, "Can't inherit from multiple C++ classes in Python."
-                                         "Use py::class_ to define the class in C++ instead.");
-        return nullptr;
-    } else {
-        return PyType_Type.tp_new(metaclass, args, kwargs);
-    }
-}
-
-/** Types with static properties need to handle `Type.static_prop = x` in a specific way.
-    By default, Python replaces the `static_property` itself, but for wrapped C++ types
-    we need to call `static_property.__set__()` in order to propagate the new value to
-    the underlying C++ data structure. */
-extern "C" inline int pybind11_meta_setattro(PyObject* obj, PyObject* name, PyObject* value) {
-    // Use `_PyType_Lookup()` instead of `PyObject_GetAttr()` in order to get the raw
-    // descriptor (`property`) instead of calling `tp_descr_get` (`property.__get__()`).
-    PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
-
-    // Call `static_property.__set__()` instead of replacing the `static_property`.
-    if (descr && PyObject_IsInstance(descr, (PyObject *) get_internals().static_property_type)) {
-#if !defined(PYPY_VERSION)
-        return Py_TYPE(descr)->tp_descr_set(descr, obj, value);
-#else
-        if (PyObject *result = PyObject_CallMethod(descr, "__set__", "OO", obj, value)) {
-            Py_DECREF(result);
-            return 0;
-        } else {
-            return -1;
-        }
-#endif
-    } else {
-        return PyType_Type.tp_setattro(obj, name, value);
-    }
-}
-
-/** This metaclass is assigned by default to all pybind11 types and is required in order
-    for static properties to function correctly. Users may override this using `py::metaclass`.
-    Return value: New reference. */
-inline PyTypeObject* make_default_metaclass() {
-    constexpr auto *name = "pybind11_type";
-    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
-
-    /* Danger zone: from now (and until PyType_Ready), make sure to
-       issue no Python C API calls which could potentially invoke the
-       garbage collector (the GC will call type_traverse(), which will in
-       turn find the newly constructed type in an invalid state) */
-    auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
-    if (!heap_type)
-        pybind11_fail("make_default_metaclass(): error allocating metaclass!");
-
-    heap_type->ht_name = name_obj.inc_ref().ptr();
-#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
-    heap_type->ht_qualname = name_obj.inc_ref().ptr();
-#endif
-
-    auto type = &heap_type->ht_type;
-    type->tp_name = name;
-    type->tp_base = &PyType_Type;
-    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
-
-    type->tp_new = pybind11_meta_new;
-    type->tp_setattro = pybind11_meta_setattro;
-
-    if (PyType_Ready(type) < 0)
-        pybind11_fail("make_default_metaclass(): failure in PyType_Ready()!");
-
-    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
-
-    return type;
-}
-
-/// Instance creation function for all pybind11 types. It only allocates space for the
-/// C++ object, but doesn't call the constructor -- an `__init__` function must do that.
-extern "C" inline PyObject *pybind11_object_new(PyTypeObject *type, PyObject *, PyObject *) {
-    PyObject *self = type->tp_alloc(type, 0);
-    auto instance = (instance_essentials<void> *) self;
-    auto tinfo = get_type_info(type);
-    instance->value = tinfo->operator_new(tinfo->type_size);
-    instance->owned = true;
-    instance->holder_constructed = false;
-    get_internals().registered_instances.emplace(instance->value, self);
-    return self;
-}
-
-/// An `__init__` function constructs the C++ object. Users should provide at least one
-/// of these using `py::init` or directly with `.def(__init__, ...)`. Otherwise, the
-/// following default function will be used which simply throws an exception.
-extern "C" inline int pybind11_object_init(PyObject *self, PyObject *, PyObject *) {
-    PyTypeObject *type = Py_TYPE(self);
-    std::string msg;
-#if defined(PYPY_VERSION)
-    msg += handle((PyObject *) type).attr("__module__").cast<std::string>() + ".";
-#endif
-    msg += type->tp_name;
-    msg += ": No constructor defined!";
-    PyErr_SetString(PyExc_TypeError, msg.c_str());
-    return -1;
-}
-
-/// Instance destructor function for all pybind11 types. It calls `type_info.dealloc`
-/// to destroy the C++ object itself, while the rest is Python bookkeeping.
-extern "C" inline void pybind11_object_dealloc(PyObject *self) {
-    auto instance = (instance_essentials<void> *) self;
-    if (instance->value) {
-        auto type = Py_TYPE(self);
-        get_type_info(type)->dealloc(self);
-
-        auto &registered_instances = get_internals().registered_instances;
-        auto range = registered_instances.equal_range(instance->value);
-        bool found = false;
-        for (auto it = range.first; it != range.second; ++it) {
-            if (type == Py_TYPE(it->second)) {
-                registered_instances.erase(it);
-                found = true;
-                break;
-            }
-        }
-        if (!found)
-            pybind11_fail("pybind11_object_dealloc(): Tried to deallocate unregistered instance!");
-
-        if (instance->weakrefs)
-            PyObject_ClearWeakRefs(self);
-
-        PyObject **dict_ptr = _PyObject_GetDictPtr(self);
-        if (dict_ptr)
-            Py_CLEAR(*dict_ptr);
-    }
-    Py_TYPE(self)->tp_free(self);
-}
-
-/** Create a type which can be used as a common base for all classes with the same
-    instance size, i.e. all classes with the same `sizeof(holder_type)`. This is
-    needed in order to satisfy Python's requirements for multiple inheritance.
-    Return value: New reference. */
-inline PyObject *make_object_base_type(size_t instance_size) {
-    auto name = "pybind11_object_" + std::to_string(instance_size);
-    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name.c_str()));
-
-    /* Danger zone: from now (and until PyType_Ready), make sure to
-       issue no Python C API calls which could potentially invoke the
-       garbage collector (the GC will call type_traverse(), which will in
-       turn find the newly constructed type in an invalid state) */
-    auto metaclass = get_internals().default_metaclass;
-    auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
-    if (!heap_type)
-        pybind11_fail("make_object_base_type(): error allocating type!");
-
-    heap_type->ht_name = name_obj.inc_ref().ptr();
-#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
-    heap_type->ht_qualname = name_obj.inc_ref().ptr();
-#endif
-
-    auto type = &heap_type->ht_type;
-    type->tp_name = strdup(name.c_str());
-    type->tp_base = &PyBaseObject_Type;
-    type->tp_basicsize = static_cast<ssize_t>(instance_size);
-    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
-
-    type->tp_new = pybind11_object_new;
-    type->tp_init = pybind11_object_init;
-    type->tp_dealloc = pybind11_object_dealloc;
-
-    /* Support weak references (needed for the keep_alive feature) */
-    type->tp_weaklistoffset = offsetof(instance_essentials<void>, weakrefs);
-
-    if (PyType_Ready(type) < 0)
-        pybind11_fail("PyType_Ready failed in make_object_base_type():" + error_string());
-
-    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
-
-    assert(!PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
-    return (PyObject *) heap_type;
-}
-
-/** Return the appropriate base type for the given instance size. The results are cached
-    in `internals.bases` so that only a single base is ever created for any size value.
-    Return value: Borrowed reference. */
-inline PyObject *internals::get_base(size_t instance_size) {
-    auto it = bases.find(instance_size);
-    if (it != bases.end()) {
-        return it->second;
-    } else {
-        auto base = make_object_base_type(instance_size);
-        bases[instance_size] = base;
-        return base;
-    }
-}
-
-/// dynamic_attr: Support for `d = instance.__dict__`.
-extern "C" inline PyObject *pybind11_get_dict(PyObject *self, void *) {
-    PyObject *&dict = *_PyObject_GetDictPtr(self);
-    if (!dict)
-        dict = PyDict_New();
-    Py_XINCREF(dict);
-    return dict;
-}
-
-/// dynamic_attr: Support for `instance.__dict__ = dict()`.
-extern "C" inline int pybind11_set_dict(PyObject *self, PyObject *new_dict, void *) {
-    if (!PyDict_Check(new_dict)) {
-        PyErr_Format(PyExc_TypeError, "__dict__ must be set to a dictionary, not a '%.200s'",
-                     Py_TYPE(new_dict)->tp_name);
-        return -1;
-    }
-    PyObject *&dict = *_PyObject_GetDictPtr(self);
-    Py_INCREF(new_dict);
-    Py_CLEAR(dict);
-    dict = new_dict;
-    return 0;
-}
-
-/// dynamic_attr: Allow the garbage collector to traverse the internal instance `__dict__`.
-extern "C" inline int pybind11_traverse(PyObject *self, visitproc visit, void *arg) {
-    PyObject *&dict = *_PyObject_GetDictPtr(self);
-    Py_VISIT(dict);
-    return 0;
-}
-
-/// dynamic_attr: Allow the GC to clear the dictionary.
-extern "C" inline int pybind11_clear(PyObject *self) {
-    PyObject *&dict = *_PyObject_GetDictPtr(self);
-    Py_CLEAR(dict);
-    return 0;
-}
-
-/// Give instances of this type a `__dict__` and opt into garbage collection.
-inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
-    auto type = &heap_type->ht_type;
-#if defined(PYPY_VERSION)
-    pybind11_fail(std::string(type->tp_name) + ": dynamic attributes are "
-                                               "currently not supported in "
-                                               "conjunction with PyPy!");
-#endif
-    type->tp_flags |= Py_TPFLAGS_HAVE_GC;
-    type->tp_dictoffset = type->tp_basicsize; // place dict at the end
-    type->tp_basicsize += sizeof(PyObject *); // and allocate enough space for it
-    type->tp_traverse = pybind11_traverse;
-    type->tp_clear = pybind11_clear;
-
-    static PyGetSetDef getset[] = {
-        {const_cast<char*>("__dict__"), pybind11_get_dict, pybind11_set_dict, nullptr, nullptr},
-        {nullptr, nullptr, nullptr, nullptr, nullptr}
-    };
-    type->tp_getset = getset;
-}
-
-/// buffer_protocol: Fill in the view as specified by flags.
-extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int flags) {
-    auto tinfo = get_type_info(Py_TYPE(obj));
-    if (view == nullptr || obj == nullptr || !tinfo || !tinfo->get_buffer) {
-        if (view)
-            view->obj = nullptr;
-        PyErr_SetString(PyExc_BufferError, "generic_type::getbuffer(): Internal error");
-        return -1;
-    }
-    memset(view, 0, sizeof(Py_buffer));
-    buffer_info *info = tinfo->get_buffer(obj, tinfo->get_buffer_data);
-    view->obj = obj;
-    view->ndim = 1;
-    view->internal = info;
-    view->buf = info->ptr;
-    view->itemsize = (ssize_t) info->itemsize;
-    view->len = view->itemsize;
-    for (auto s : info->shape)
-        view->len *= s;
-    if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT)
-        view->format = const_cast<char *>(info->format.c_str());
-    if ((flags & PyBUF_STRIDES) == PyBUF_STRIDES) {
-        view->ndim = (int) info->ndim;
-        view->strides = (ssize_t *) &info->strides[0];
-        view->shape = (ssize_t *) &info->shape[0];
-    }
-    Py_INCREF(view->obj);
-    return 0;
-}
-
-/// buffer_protocol: Release the resources of the buffer.
-extern "C" inline void pybind11_releasebuffer(PyObject *, Py_buffer *view) {
-    delete (buffer_info *) view->internal;
-}
-
-/// Give this type a buffer interface.
-inline void enable_buffer_protocol(PyHeapTypeObject *heap_type) {
-    heap_type->ht_type.tp_as_buffer = &heap_type->as_buffer;
-#if PY_MAJOR_VERSION < 3
-    heap_type->ht_type.tp_flags |= Py_TPFLAGS_HAVE_NEWBUFFER;
-#endif
-
-    heap_type->as_buffer.bf_getbuffer = pybind11_getbuffer;
-    heap_type->as_buffer.bf_releasebuffer = pybind11_releasebuffer;
-}
-
-/** Create a brand new Python type according to the `type_record` specification.
-    Return value: New reference. */
-inline PyObject* make_new_python_type(const type_record &rec) {
-    auto name = reinterpret_steal<object>(PYBIND11_FROM_STRING(rec.name));
-
-#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
-    auto ht_qualname = name;
-    if (rec.scope && hasattr(rec.scope, "__qualname__")) {
-        ht_qualname = reinterpret_steal<object>(
-            PyUnicode_FromFormat("%U.%U", rec.scope.attr("__qualname__").ptr(), name.ptr()));
-    }
-#endif
-
-    object module;
-    if (rec.scope) {
-        if (hasattr(rec.scope, "__module__"))
-            module = rec.scope.attr("__module__");
-        else if (hasattr(rec.scope, "__name__"))
-            module = rec.scope.attr("__name__");
-    }
-
-#if !defined(PYPY_VERSION)
-    const auto full_name = module ? str(module).cast<std::string>() + "." + rec.name
-                                  : std::string(rec.name);
-#else
-    const auto full_name = std::string(rec.name);
-#endif
-
-    char *tp_doc = nullptr;
-    if (rec.doc && options::show_user_defined_docstrings()) {
-        /* Allocate memory for docstring (using PyObject_MALLOC, since
-           Python will free this later on) */
-        size_t size = strlen(rec.doc) + 1;
-        tp_doc = (char *) PyObject_MALLOC(size);
-        memcpy((void *) tp_doc, rec.doc, size);
-    }
-
-    auto &internals = get_internals();
-    auto bases = tuple(rec.bases);
-    auto base = (bases.size() == 0) ? internals.get_base(rec.instance_size)
-                                    : bases[0].ptr();
-
-    /* Danger zone: from now (and until PyType_Ready), make sure to
-       issue no Python C API calls which could potentially invoke the
-       garbage collector (the GC will call type_traverse(), which will in
-       turn find the newly constructed type in an invalid state) */
-    auto metaclass = rec.metaclass.ptr() ? (PyTypeObject *) rec.metaclass.ptr()
-                                         : internals.default_metaclass;
-
-    auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
-    if (!heap_type)
-        pybind11_fail(std::string(rec.name) + ": Unable to create type object!");
-
-    heap_type->ht_name = name.release().ptr();
-#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
-    heap_type->ht_qualname = ht_qualname.release().ptr();
-#endif
-
-    auto type = &heap_type->ht_type;
-    type->tp_name = strdup(full_name.c_str());
-    type->tp_doc = tp_doc;
-    type->tp_base = (PyTypeObject *) handle(base).inc_ref().ptr();
-    type->tp_basicsize = static_cast<ssize_t>(rec.instance_size);
-    if (bases.size() > 0)
-        type->tp_bases = bases.release().ptr();
-
-    /* Don't inherit base __init__ */
-    type->tp_init = pybind11_object_init;
-
-    /* Supported protocols */
-    type->tp_as_number = &heap_type->as_number;
-    type->tp_as_sequence = &heap_type->as_sequence;
-    type->tp_as_mapping = &heap_type->as_mapping;
-
-    /* Flags */
-    type->tp_flags |= Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
-#if PY_MAJOR_VERSION < 3
-    type->tp_flags |= Py_TPFLAGS_CHECKTYPES;
-#endif
-
-    if (rec.dynamic_attr)
-        enable_dynamic_attributes(heap_type);
-
-    if (rec.buffer_protocol)
-        enable_buffer_protocol(heap_type);
-
-    if (PyType_Ready(type) < 0)
-        pybind11_fail(std::string(rec.name) + ": PyType_Ready failed (" + error_string() + ")!");
-
-    assert(rec.dynamic_attr ? PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC)
-                            : !PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
-
-    /* Register type with the parent scope */
-    if (rec.scope)
-        setattr(rec.scope, rec.name, (PyObject *) type);
-
-    if (module) // Needed by pydoc
-        setattr((PyObject *) type, "__module__", module);
-
-    return (PyObject *) type;
-}
-
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
diff --git a/libs/pybind/pybind11/common.h b/libs/pybind/pybind11/common.h
index ac2be7aeff..6c8a4f1e88 100644
--- a/libs/pybind/pybind11/common.h
+++ b/libs/pybind/pybind11/common.h
@@ -1,719 +1,2 @@
-/*
-    pybind11/common.h -- Basic macros
-
-    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
-
-    All rights reserved. Use of this source code is governed by a
-    BSD-style license that can be found in the LICENSE file.
-*/
-
-#pragma once
-
-#if !defined(NAMESPACE_BEGIN)
-#  define NAMESPACE_BEGIN(name) namespace name {
-#endif
-#if !defined(NAMESPACE_END)
-#  define NAMESPACE_END(name) }
-#endif
-
-// Neither MSVC nor Intel support enough of C++14 yet (in particular, as of MSVC 2015 and ICC 17
-// beta, neither support extended constexpr, which we rely on in descr.h), so don't enable pybind
-// CPP14 features for them.
-#if !defined(_MSC_VER) && !defined(__INTEL_COMPILER)
-#  if __cplusplus >= 201402L
-#    define PYBIND11_CPP14
-#    if __cplusplus > 201402L /* Temporary: should be updated to >= the final C++17 value once known */
-#      define PYBIND11_CPP17
-#    endif
-#  endif
-#endif
-
-// Compiler version assertions
-#if defined(__INTEL_COMPILER)
-#  if __INTEL_COMPILER < 1500
-#    error pybind11 requires Intel C++ compiler v15 or newer
-#  endif
-#elif defined(__clang__) && !defined(__apple_build_version__)
-#  if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 3)
-#    error pybind11 requires clang 3.3 or newer
-#  endif
-#elif defined(__clang__)
-// Apple changes clang version macros to its Xcode version; the first Xcode release based on
-// (upstream) clang 3.3 was Xcode 5:
-#  if __clang_major__ < 5
-#    error pybind11 requires Xcode/clang 5.0 or newer
-#  endif
-#elif defined(__GNUG__)
-#  if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
-#    error pybind11 requires gcc 4.8 or newer
-#  endif
-#elif defined(_MSC_VER)
-// Pybind hits various compiler bugs in 2015u2 and earlier, and also makes use of some stl features
-// (e.g. std::negation) added in 2015u3:
-#  if _MSC_FULL_VER < 190024210
-#    error pybind11 requires MSVC 2015 update 3 or newer
-#  endif
-#endif
-
-#if !defined(PYBIND11_EXPORT)
-#  if defined(WIN32) || defined(_WIN32)
-#    define PYBIND11_EXPORT __declspec(dllexport)
-#  else
-#    define PYBIND11_EXPORT __attribute__ ((visibility("default")))
-#  endif
-#endif
-
-#if defined(_MSC_VER)
-#  define PYBIND11_NOINLINE __declspec(noinline)
-#else
-#  define PYBIND11_NOINLINE __attribute__ ((noinline))
-#endif
-
-#if defined(PYBIND11_CPP14)
-#  define PYBIND11_DEPRECATED(reason) [[deprecated(reason)]]
-#elif defined(__clang__)
-#  define PYBIND11_DEPRECATED(reason) __attribute__((deprecated(reason)))
-#elif defined(__GNUG__)
-#  define PYBIND11_DEPRECATED(reason) __attribute__((deprecated))
-#elif defined(_MSC_VER)
-#  define PYBIND11_DEPRECATED(reason) __declspec(deprecated)
-#endif
-
-#define PYBIND11_VERSION_MAJOR 2
-#define PYBIND11_VERSION_MINOR 1
-#define PYBIND11_VERSION_PATCH 1
-
-/// Include Python header, disable linking to pythonX_d.lib on Windows in debug mode
-#if defined(_MSC_VER)
-#  if (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 4)
-#    define HAVE_ROUND 1
-#  endif
-#  pragma warning(push)
-#  pragma warning(disable: 4510 4610 4512 4005)
-#  if defined(_DEBUG)
-#    define PYBIND11_DEBUG_MARKER
-#    undef _DEBUG
-#  endif
-#endif
-
-#include <Python.h>
-#include <frameobject.h>
-#include <pythread.h>
-
-#if defined(_WIN32) && (defined(min) || defined(max))
-#  error Macro clash with min and max -- define NOMINMAX when compiling your program on Windows
-#endif
-
-#if defined(isalnum)
-#  undef isalnum
-#  undef isalpha
-#  undef islower
-#  undef isspace
-#  undef isupper
-#  undef tolower
-#  undef toupper
-#endif
-
-#if defined(_MSC_VER)
-#  if defined(PYBIND11_DEBUG_MARKER)
-#    define _DEBUG
-#    undef PYBIND11_DEBUG_MARKER
-#  endif
-#  pragma warning(pop)
-#endif
-
-#include <cstddef>
-#include <forward_list>
-#include <vector>
-#include <string>
-#include <stdexcept>
-#include <unordered_set>
-#include <unordered_map>
-#include <memory>
-#include <typeindex>
-#include <type_traits>
-
-#if PY_MAJOR_VERSION >= 3 /// Compatibility macros for various Python versions
-#define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyInstanceMethod_New(ptr)
-#define PYBIND11_BYTES_CHECK PyBytes_Check
-#define PYBIND11_BYTES_FROM_STRING PyBytes_FromString
-#define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyBytes_FromStringAndSize
-#define PYBIND11_BYTES_AS_STRING_AND_SIZE PyBytes_AsStringAndSize
-#define PYBIND11_BYTES_AS_STRING PyBytes_AsString
-#define PYBIND11_BYTES_SIZE PyBytes_Size
-#define PYBIND11_LONG_CHECK(o) PyLong_Check(o)
-#define PYBIND11_LONG_AS_LONGLONG(o) PyLong_AsLongLong(o)
-#define PYBIND11_LONG_AS_UNSIGNED_LONGLONG(o) PyLong_AsUnsignedLongLong(o)
-#define PYBIND11_BYTES_NAME "bytes"
-#define PYBIND11_STRING_NAME "str"
-#define PYBIND11_SLICE_OBJECT PyObject
-#define PYBIND11_FROM_STRING PyUnicode_FromString
-#define PYBIND11_STR_TYPE ::pybind11::str
-#define PYBIND11_PLUGIN_IMPL(name) \
-    extern "C" PYBIND11_EXPORT PyObject *PyInit_##name()
-#else
-#define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyMethod_New(ptr, nullptr, class_)
-#define PYBIND11_BYTES_CHECK PyString_Check
-#define PYBIND11_BYTES_FROM_STRING PyString_FromString
-#define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyString_FromStringAndSize
-#define PYBIND11_BYTES_AS_STRING_AND_SIZE PyString_AsStringAndSize
-#define PYBIND11_BYTES_AS_STRING PyString_AsString
-#define PYBIND11_BYTES_SIZE PyString_Size
-#define PYBIND11_LONG_CHECK(o) (PyInt_Check(o) || PyLong_Check(o))
-#define PYBIND11_LONG_AS_LONGLONG(o) (PyInt_Check(o) ? (long long) PyLong_AsLong(o) : PyLong_AsLongLong(o))
-#define PYBIND11_LONG_AS_UNSIGNED_LONGLONG(o) (PyInt_Check(o) ? (unsigned long long) PyLong_AsUnsignedLong(o) : PyLong_AsUnsignedLongLong(o))
-#define PYBIND11_BYTES_NAME "str"
-#define PYBIND11_STRING_NAME "unicode"
-#define PYBIND11_SLICE_OBJECT PySliceObject
-#define PYBIND11_FROM_STRING PyString_FromString
-#define PYBIND11_STR_TYPE ::pybind11::bytes
-#define PYBIND11_PLUGIN_IMPL(name) \
-    static PyObject *pybind11_init_wrapper();               \
-    extern "C" PYBIND11_EXPORT void init##name() {          \
-        (void)pybind11_init_wrapper();                      \
-    }                                                       \
-    PyObject *pybind11_init_wrapper()
-#endif
-
-#if PY_VERSION_HEX >= 0x03050000 && PY_VERSION_HEX < 0x03050200
-extern "C" {
-    struct _Py_atomic_address { void *value; };
-    PyAPI_DATA(_Py_atomic_address) _PyThreadState_Current;
-}
-#endif
-
-#define PYBIND11_TRY_NEXT_OVERLOAD ((PyObject *) 1) // special failure return code
-#define PYBIND11_STRINGIFY(x) #x
-#define PYBIND11_TOSTRING(x) PYBIND11_STRINGIFY(x)
-#define PYBIND11_INTERNALS_ID "__pybind11_" \
-    PYBIND11_TOSTRING(PYBIND11_VERSION_MAJOR) "_" PYBIND11_TOSTRING(PYBIND11_VERSION_MINOR) "__"
-
-/** \rst
-    This macro creates the entry point that will be invoked when the Python interpreter
-    imports a plugin library. Please create a `module` in the function body and return
-    the pointer to its underlying Python object at the end.
-
-    .. code-block:: cpp
-
-        PYBIND11_PLUGIN(example) {
-            pybind11::module m("example", "pybind11 example plugin");
-            /// Set up bindings here
-            return m.ptr();
-        }
-\endrst */
-#define PYBIND11_PLUGIN(name)                                                  \
-    static PyObject *pybind11_init();                                          \
-    PYBIND11_PLUGIN_IMPL(name) {                                               \
-        int major, minor;                                                      \
-        if (sscanf(Py_GetVersion(), "%i.%i", &major, &minor) != 2) {           \
-            PyErr_SetString(PyExc_ImportError, "Can't parse Python version."); \
-            return nullptr;                                                    \
-        } else if (major != PY_MAJOR_VERSION || minor != PY_MINOR_VERSION) {   \
-            PyErr_Format(PyExc_ImportError,                                    \
-                         "Python version mismatch: module was compiled for "   \
-                         "version %i.%i, while the interpreter is running "    \
-                         "version %i.%i.", PY_MAJOR_VERSION, PY_MINOR_VERSION, \
-                         major, minor);                                        \
-            return nullptr;                                                    \
-        }                                                                      \
-        try {                                                                  \
-            return pybind11_init();                                            \
-        } catch (pybind11::error_already_set &e) {                             \
-            e.clear();                                                         \
-            PyErr_SetString(PyExc_ImportError, e.what());                      \
-            return nullptr;                                                    \
-        } catch (const std::exception &e) {                                    \
-            PyErr_SetString(PyExc_ImportError, e.what());                      \
-            return nullptr;                                                    \
-        }                                                                      \
-    }                                                                          \
-    PyObject *pybind11_init()
-
-NAMESPACE_BEGIN(pybind11)
-
-using ssize_t = Py_ssize_t;
-using size_t  = std::size_t;
-
-/// Approach used to cast a previously unknown C++ instance into a Python object
-enum class return_value_policy : uint8_t {
-    /** This is the default return value policy, which falls back to the policy
-        return_value_policy::take_ownership when the return value is a pointer.
-        Otherwise, it uses return_value::move or return_value::copy for rvalue
-        and lvalue references, respectively. See below for a description of what
-        all of these different policies do. */
-    automatic = 0,
-
-    /** As above, but use policy return_value_policy::reference when the return
-        value is a pointer. This is the default conversion policy for function
-        arguments when calling Python functions manually from C++ code (i.e. via
-        handle::operator()). You probably won't need to use this. */
-    automatic_reference,
-
-    /** Reference an existing object (i.e. do not create a new copy) and take
-        ownership. Python will call the destructor and delete operator when the
-        object’s reference count reaches zero. Undefined behavior ensues when
-        the C++ side does the same.. */
-    take_ownership,
-
-    /** Create a new copy of the returned object, which will be owned by
-        Python. This policy is comparably safe because the lifetimes of the two
-        instances are decoupled. */
-    copy,
-
-    /** Use std::move to move the return value contents into a new instance
-        that will be owned by Python. This policy is comparably safe because the
-        lifetimes of the two instances (move source and destination) are
-        decoupled. */
-    move,
-
-    /** Reference an existing object, but do not take ownership. The C++ side
-        is responsible for managing the object’s lifetime and deallocating it
-        when it is no longer used. Warning: undefined behavior will ensue when
-        the C++ side deletes an object that is still referenced and used by
-        Python. */
-    reference,
-
-    /** This policy only applies to methods and properties. It references the
-        object without taking ownership similar to the above
-        return_value_policy::reference policy. In contrast to that policy, the
-        function or property’s implicit this argument (called the parent) is
-        considered to be the the owner of the return value (the child).
-        pybind11 then couples the lifetime of the parent to the child via a
-        reference relationship that ensures that the parent cannot be garbage
-        collected while Python is still using the child. More advanced
-        variations of this scheme are also possible using combinations of
-        return_value_policy::reference and the keep_alive call policy */
-    reference_internal
-};
-
-/// Information record describing a Python buffer object
-struct buffer_info {
-    void *ptr = nullptr;         // Pointer to the underlying storage
-    size_t itemsize = 0;         // Size of individual items in bytes
-    size_t size = 0;             // Total number of entries
-    std::string format;          // For homogeneous buffers, this should be set to format_descriptor<T>::format()
-    size_t ndim = 0;             // Number of dimensions
-    std::vector<size_t> shape;   // Shape of the tensor (1 entry per dimension)
-    std::vector<size_t> strides; // Number of entries between adjacent entries (for each per dimension)
-
-    buffer_info() { }
-
-    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t ndim,
-                const std::vector<size_t> &shape, const std::vector<size_t> &strides)
-        : ptr(ptr), itemsize(itemsize), size(1), format(format),
-          ndim(ndim), shape(shape), strides(strides) {
-        for (size_t i = 0; i < ndim; ++i)
-            size *= shape[i];
-    }
-
-    buffer_info(void *ptr, size_t itemsize, const std::string &format, size_t size)
-    : buffer_info(ptr, itemsize, format, 1, std::vector<size_t> { size },
-                  std::vector<size_t> { itemsize }) { }
-
-    explicit buffer_info(Py_buffer *view, bool ownview = true)
-        : ptr(view->buf), itemsize((size_t) view->itemsize), size(1), format(view->format),
-          ndim((size_t) view->ndim), shape((size_t) view->ndim), strides((size_t) view->ndim), view(view), ownview(ownview) {
-        for (size_t i = 0; i < (size_t) view->ndim; ++i) {
-            shape[i] = (size_t) view->shape[i];
-            strides[i] = (size_t) view->strides[i];
-            size *= shape[i];
-        }
-    }
-
-    buffer_info(const buffer_info &) = delete;
-    buffer_info& operator=(const buffer_info &) = delete;
-
-    buffer_info(buffer_info &&other) {
-        (*this) = std::move(other);
-    }
-
-    buffer_info& operator=(buffer_info &&rhs) {
-        ptr = rhs.ptr;
-        itemsize = rhs.itemsize;
-        size = rhs.size;
-        format = std::move(rhs.format);
-        ndim = rhs.ndim;
-        shape = std::move(rhs.shape);
-        strides = std::move(rhs.strides);
-        std::swap(view, rhs.view);
-        std::swap(ownview, rhs.ownview);
-        return *this;
-    }
-
-    ~buffer_info() {
-        if (view && ownview) { PyBuffer_Release(view); delete view; }
-    }
-
-private:
-    Py_buffer *view = nullptr;
-    bool ownview = false;
-};
-
-NAMESPACE_BEGIN(detail)
-
-inline static constexpr int log2(size_t n, int k = 0) { return (n <= 1) ? k : log2(n >> 1, k + 1); }
-
-inline std::string error_string();
-
-/// Core part of the 'instance' type which POD (needed to be able to use 'offsetof')
-template <typename type> struct instance_essentials {
-    PyObject_HEAD
-    type *value;
-    PyObject *weakrefs;
-    bool owned : 1;
-    bool holder_constructed : 1;
-};
-
-/// PyObject wrapper around generic types, includes a special holder type that is responsible for lifetime management
-template <typename type, typename holder_type = std::unique_ptr<type>> struct instance : instance_essentials<type> {
-    holder_type holder;
-};
-
-struct overload_hash {
-    inline size_t operator()(const std::pair<const PyObject *, const char *>& v) const {
-        size_t value = std::hash<const void *>()(v.first);
-        value ^= std::hash<const void *>()(v.second)  + 0x9e3779b9 + (value<<6) + (value>>2);
-        return value;
-    }
-};
-
-/// Internal data structure used to track registered instances and types
-struct internals {
-    std::unordered_map<std::type_index, void*> registered_types_cpp;   // std::type_index -> type_info
-    std::unordered_map<const void *, void*> registered_types_py;       // PyTypeObject* -> type_info
-    std::unordered_multimap<const void *, void*> registered_instances; // void * -> PyObject*
-    std::unordered_set<std::pair<const PyObject *, const char *>, overload_hash> inactive_overload_cache;
-    std::unordered_map<std::type_index, std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
-    std::forward_list<void (*) (std::exception_ptr)> registered_exception_translators;
-    std::unordered_map<std::string, void *> shared_data; // Custom data to be shared across extensions
-    PyTypeObject *static_property_type;
-    PyTypeObject *default_metaclass;
-    std::unordered_map<size_t, PyObject *> bases; // one base type per `instance_size` (very few)
-#if defined(WITH_THREAD)
-    decltype(PyThread_create_key()) tstate = 0; // Usually an int but a long on Cygwin64 with Python 3.x
-    PyInterpreterState *istate = nullptr;
-#endif
-
-    /// Return the appropriate base type for the given instance size
-    PyObject *get_base(size_t instance_size);
-};
-
-/// Return a reference to the current 'internals' information
-inline internals &get_internals();
-
-/// from __cpp_future__ import (convenient aliases from C++14/17)
-#ifdef PYBIND11_CPP14
-using std::enable_if_t;
-using std::conditional_t;
-using std::remove_cv_t;
-#else
-template <bool B, typename T = void> using enable_if_t = typename std::enable_if<B, T>::type;
-template <bool B, typename T, typename F> using conditional_t = typename std::conditional<B, T, F>::type;
-template <typename T> using remove_cv_t = typename std::remove_cv<T>::type;
-#endif
-
-/// Index sequences
-#if defined(PYBIND11_CPP14) || defined(_MSC_VER)
-using std::index_sequence;
-using std::make_index_sequence;
-#else
-template<size_t ...> struct index_sequence  { };
-template<size_t N, size_t ...S> struct make_index_sequence_impl : make_index_sequence_impl <N - 1, N - 1, S...> { };
-template<size_t ...S> struct make_index_sequence_impl <0, S...> { typedef index_sequence<S...> type; };
-template<size_t N> using make_index_sequence = typename make_index_sequence_impl<N>::type;
-#endif
-
-/// Backports of std::bool_constant and std::negation to accomodate older compilers
-template <bool B> using bool_constant = std::integral_constant<bool, B>;
-template <typename T> struct negation : bool_constant<!T::value> { };
-
-template <typename...> struct void_t_impl { using type = void; };
-template <typename... Ts> using void_t = typename void_t_impl<Ts...>::type;
-
-/// Compile-time all/any/none of that check the boolean value of all template types
-#ifdef __cpp_fold_expressions
-template <class... Ts> using all_of = bool_constant<(Ts::value && ...)>;
-template <class... Ts> using any_of = bool_constant<(Ts::value || ...)>;
-#elif !defined(_MSC_VER)
-template <bool...> struct bools {};
-template <class... Ts> using all_of = std::is_same<
-    bools<Ts::value..., true>,
-    bools<true, Ts::value...>>;
-template <class... Ts> using any_of = negation<all_of<negation<Ts>...>>;
-#else
-// MSVC has trouble with the above, but supports std::conjunction, which we can use instead (albeit
-// at a slight loss of compilation efficiency).
-template <class... Ts> using all_of = std::conjunction<Ts...>;
-template <class... Ts> using any_of = std::disjunction<Ts...>;
-#endif
-template <class... Ts> using none_of = negation<any_of<Ts...>>;
-
-template <class T, template<class> class... Predicates> using satisfies_all_of = all_of<Predicates<T>...>;
-template <class T, template<class> class... Predicates> using satisfies_any_of = any_of<Predicates<T>...>;
-template <class T, template<class> class... Predicates> using satisfies_none_of = none_of<Predicates<T>...>;
-
-/// Strip the class from a method type
-template <typename T> struct remove_class { };
-template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...)> { typedef R type(A...); };
-template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...) const> { typedef R type(A...); };
-
-/// Helper template to strip away type modifiers
-template <typename T> struct intrinsic_type                       { typedef T type; };
-template <typename T> struct intrinsic_type<const T>              { typedef typename intrinsic_type<T>::type type; };
-template <typename T> struct intrinsic_type<T*>                   { typedef typename intrinsic_type<T>::type type; };
-template <typename T> struct intrinsic_type<T&>                   { typedef typename intrinsic_type<T>::type type; };
-template <typename T> struct intrinsic_type<T&&>                  { typedef typename intrinsic_type<T>::type type; };
-template <typename T, size_t N> struct intrinsic_type<const T[N]> { typedef typename intrinsic_type<T>::type type; };
-template <typename T, size_t N> struct intrinsic_type<T[N]>       { typedef typename intrinsic_type<T>::type type; };
-template <typename T> using intrinsic_t = typename intrinsic_type<T>::type;
-
-/// Helper type to replace 'void' in some expressions
-struct void_type { };
-
-/// Helper template which holds a list of types
-template <typename...> struct type_list { };
-
-/// Compile-time integer sum
-#ifdef __cpp_fold_expressions
-template <typename... Ts> constexpr size_t constexpr_sum(Ts... ns) { return (0 + ... + size_t{ns}); }
-#else
-constexpr size_t constexpr_sum() { return 0; }
-template <typename T, typename... Ts>
-constexpr size_t constexpr_sum(T n, Ts... ns) { return size_t{n} + constexpr_sum(ns...); }
-#endif
-
-NAMESPACE_BEGIN(constexpr_impl)
-/// Implementation details for constexpr functions
-constexpr int first(int i) { return i; }
-template <typename T, typename... Ts>
-constexpr int first(int i, T v, Ts... vs) { return v ? i : first(i + 1, vs...); }
-
-constexpr int last(int /*i*/, int result) { return result; }
-template <typename T, typename... Ts>
-constexpr int last(int i, int result, T v, Ts... vs) { return last(i + 1, v ? i : result, vs...); }
-NAMESPACE_END(constexpr_impl)
-
-/// Return the index of the first type in Ts which satisfies Predicate<T>.  Returns sizeof...(Ts) if
-/// none match.
-template <template<typename> class Predicate, typename... Ts>
-constexpr int constexpr_first() { return constexpr_impl::first(0, Predicate<Ts>::value...); }
-
-/// Return the index of the last type in Ts which satisfies Predicate<T>, or -1 if none match.
-template <template<typename> class Predicate, typename... Ts>
-constexpr int constexpr_last() { return constexpr_impl::last(0, -1, Predicate<Ts>::value...); }
-
-// Extracts the first type from the template parameter pack matching the predicate, or Default if none match.
-template <template<class> class Predicate, class Default, class... Ts> struct first_of;
-template <template<class> class Predicate, class Default> struct first_of<Predicate, Default> {
-    using type = Default;
-};
-template <template<class> class Predicate, class Default, class T, class... Ts>
-struct first_of<Predicate, Default, T, Ts...> {
-    using type = typename std::conditional<
-        Predicate<T>::value,
-        T,
-        typename first_of<Predicate, Default, Ts...>::type
-    >::type;
-};
-template <template<class> class Predicate, class Default, class... T> using first_of_t = typename first_of<Predicate, Default, T...>::type;
-
-/// Defer the evaluation of type T until types Us are instantiated
-template <typename T, typename... /*Us*/> struct deferred_type { using type = T; };
-template <typename T, typename... Us> using deferred_t = typename deferred_type<T, Us...>::type;
-
-template <template<typename...> class Base>
-struct is_template_base_of_impl {
-    template <typename... Us> static std::true_type check(Base<Us...> *);
-    static std::false_type check(...);
-};
-
-/// Check if a template is the base of a type. For example:
-/// `is_template_base_of<Base, T>` is true if `struct T : Base<U> {}` where U can be anything
-template <template<typename...> class Base, typename T>
-#if !defined(_MSC_VER)
-using is_template_base_of = decltype(is_template_base_of_impl<Base>::check((remove_cv_t<T>*)nullptr));
-#else // MSVC2015 has trouble with decltype in template aliases
-struct is_template_base_of : decltype(is_template_base_of_impl<Base>::check((remove_cv_t<T>*)nullptr)) { };
-#endif
-
-/// Check if T is std::shared_ptr<U> where U can be anything
-template <typename T> struct is_shared_ptr : std::false_type { };
-template <typename U> struct is_shared_ptr<std::shared_ptr<U>> : std::true_type { };
-
-/// Ignore that a variable is unused in compiler warnings
-inline void ignore_unused(const int *) { }
-
-NAMESPACE_END(detail)
-
-/// Returns a named pointer that is shared among all extension modules (using the same
-/// pybind11 version) running in the current interpreter. Names starting with underscores
-/// are reserved for internal usage. Returns `nullptr` if no matching entry was found.
-inline PYBIND11_NOINLINE void* get_shared_data(const std::string& name) {
-    auto& internals = detail::get_internals();
-    auto it = internals.shared_data.find(name);
-    return it != internals.shared_data.end() ? it->second : nullptr;
-}
-
-/// Set the shared data that can be later recovered by `get_shared_data()`.
-inline PYBIND11_NOINLINE void *set_shared_data(const std::string& name, void *data) {
-    detail::get_internals().shared_data[name] = data;
-    return data;
-}
-
-/// Returns a typed reference to a shared data entry (by using `get_shared_data()`) if
-/// such entry exists. Otherwise, a new object of default-constructible type `T` is
-/// added to the shared data under the given name and a reference to it is returned.
-template<typename T> T& get_or_create_shared_data(const std::string& name) {
-    auto& internals = detail::get_internals();
-    auto it = internals.shared_data.find(name);
-    T* ptr = (T*) (it != internals.shared_data.end() ? it->second : nullptr);
-    if (!ptr) {
-        ptr = new T();
-        internals.shared_data[name] = ptr;
-    }
-    return *ptr;
-}
-
-/// Fetch and hold an error which was already set in Python
-class error_already_set : public std::runtime_error {
-public:
-    error_already_set() : std::runtime_error(detail::error_string()) {
-        PyErr_Fetch(&type, &value, &trace);
-    }
-
-    error_already_set(const error_already_set &) = delete;
-
-    error_already_set(error_already_set &&e)
-        : std::runtime_error(e.what()), type(e.type), value(e.value),
-          trace(e.trace) { e.type = e.value = e.trace = nullptr; }
-
-    inline ~error_already_set(); // implementation in pybind11.h
-
-    error_already_set& operator=(const error_already_set &) = delete;
-
-    /// Give the error back to Python
-    void restore() { PyErr_Restore(type, value, trace); type = value = trace = nullptr; }
-
-    /// Clear the held Python error state (the C++ `what()` message remains intact)
-    void clear() { restore(); PyErr_Clear(); }
-
-private:
-    PyObject *type, *value, *trace;
-};
-
-/// C++ bindings of builtin Python exceptions
-class builtin_exception : public std::runtime_error {
-public:
-    using std::runtime_error::runtime_error;
-    /// Set the error using the Python C API
-    virtual void set_error() const = 0;
-};
-
-#define PYBIND11_RUNTIME_EXCEPTION(name, type) \
-    class name : public builtin_exception { public: \
-        using builtin_exception::builtin_exception; \
-        name() : name("") { } \
-        void set_error() const override { PyErr_SetString(type, what()); } \
-    };
-
-PYBIND11_RUNTIME_EXCEPTION(stop_iteration, PyExc_StopIteration)
-PYBIND11_RUNTIME_EXCEPTION(index_error, PyExc_IndexError)
-PYBIND11_RUNTIME_EXCEPTION(key_error, PyExc_KeyError)
-PYBIND11_RUNTIME_EXCEPTION(value_error, PyExc_ValueError)
-PYBIND11_RUNTIME_EXCEPTION(type_error, PyExc_TypeError)
-PYBIND11_RUNTIME_EXCEPTION(cast_error, PyExc_RuntimeError) /// Thrown when pybind11::cast or handle::call fail due to a type casting error
-PYBIND11_RUNTIME_EXCEPTION(reference_cast_error, PyExc_RuntimeError) /// Used internally
-
-[[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const char *reason) { throw std::runtime_error(reason); }
-[[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const std::string &reason) { throw std::runtime_error(reason); }
-
-template <typename T, typename SFINAE = void> struct format_descriptor { };
-
-NAMESPACE_BEGIN(detail)
-// Returns the index of the given type in the type char array below, and in the list in numpy.h
-// The order here is: bool; 8 ints ((signed,unsigned)x(8,16,32,64)bits); float,double,long double;
-// complex float,double,long double.  Note that the long double types only participate when long
-// double is actually longer than double (it isn't under MSVC).
-// NB: not only the string below but also complex.h and numpy.h rely on this order.
-template <typename T, typename SFINAE = void> struct is_fmt_numeric { static constexpr bool value = false; };
-template <typename T> struct is_fmt_numeric<T, enable_if_t<std::is_arithmetic<T>::value>> {
-    static constexpr bool value = true;
-    static constexpr int index = std::is_same<T, bool>::value ? 0 : 1 + (
-        std::is_integral<T>::value ? detail::log2(sizeof(T))*2 + std::is_unsigned<T>::value : 8 + (
-        std::is_same<T, double>::value ? 1 : std::is_same<T, long double>::value ? 2 : 0));
-};
-NAMESPACE_END(detail)
-
-template <typename T> struct format_descriptor<T, detail::enable_if_t<detail::is_fmt_numeric<T>::value>> {
-    static constexpr const char c = "?bBhHiIqQfdgFDG"[detail::is_fmt_numeric<T>::index];
-    static constexpr const char value[2] = { c, '\0' };
-    static std::string format() { return std::string(1, c); }
-};
-
-template <typename T> constexpr const char format_descriptor<
-    T, detail::enable_if_t<detail::is_fmt_numeric<T>::value>>::value[2];
-
-NAMESPACE_BEGIN(detail)
-
-template <typename T, typename SFINAE = void> struct compare_buffer_info {
-    static bool compare(const buffer_info& b) {
-        return b.format == format_descriptor<T>::format() && b.itemsize == sizeof(T);
-    }
-};
-
-template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
-    static bool compare(const buffer_info& b) {
-        return b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value ||
-            ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) ||
-            ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n")));
-    }
-};
-
-NAMESPACE_END(detail)
-
-/// RAII wrapper that temporarily clears any Python error state
-struct error_scope {
-    PyObject *type, *value, *trace;
-    error_scope() { PyErr_Fetch(&type, &value, &trace); }
-    ~error_scope() { PyErr_Restore(type, value, trace); }
-};
-
-/// Dummy destructor wrapper that can be used to expose classes with a private destructor
-struct nodelete { template <typename T> void operator()(T*) { } };
-
-// overload_cast requires variable templates: C++14 or MSVC
-#if defined(PYBIND11_CPP14) || defined(_MSC_VER)
-#define PYBIND11_OVERLOAD_CAST 1
-
-NAMESPACE_BEGIN(detail)
-template <typename... Args>
-struct overload_cast_impl {
-    template <typename Return>
-    constexpr auto operator()(Return (*pf)(Args...)) const noexcept
-                              -> decltype(pf) { return pf; }
-
-    template <typename Return, typename Class>
-    constexpr auto operator()(Return (Class::*pmf)(Args...), std::false_type = {}) const noexcept
-                              -> decltype(pmf) { return pmf; }
-
-    template <typename Return, typename Class>
-    constexpr auto operator()(Return (Class::*pmf)(Args...) const, std::true_type) const noexcept
-                              -> decltype(pmf) { return pmf; }
-};
-NAMESPACE_END(detail)
-
-/// Syntax sugar for resolving overloaded function pointers:
-///  - regular: static_cast<Return (Class::*)(Arg0, Arg1, Arg2)>(&Class::func)
-///  - sweet:   overload_cast<Arg0, Arg1, Arg2>(&Class::func)
-template <typename... Args>
-static constexpr detail::overload_cast_impl<Args...> overload_cast = {};
-// MSVC 2015 only accepts this particular initialization syntax for this variable template.
-
-/// Const member function selector for overload_cast
-///  - regular: static_cast<Return (Class::*)(Arg) const>(&Class::func)
-///  - sweet:   overload_cast<Arg>(&Class::func, const_)
-static constexpr auto const_ = std::true_type{};
-
-#endif // overload_cast
-
-NAMESPACE_END(pybind11)
+#include "detail/common.h"
+#warning "Including 'common.h' is deprecated. It will be removed in v3.0. Use 'pybind11.h'."
diff --git a/libs/pybind/pybind11/complex.h b/libs/pybind/pybind11/complex.h
index 945ca0710f..f8327eb373 100644
--- a/libs/pybind/pybind11/complex.h
+++ b/libs/pybind/pybind11/complex.h
@@ -17,11 +17,24 @@
 #  undef I
 #endif
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
-// The format codes are already in the string in common.h, we just need to provide a specialization
-template <typename T> struct is_fmt_numeric<std::complex<T>> {
+template <typename T> struct format_descriptor<std::complex<T>, detail::enable_if_t<std::is_floating_point<T>::value>> {
+    static constexpr const char c = format_descriptor<T>::c;
+    static constexpr const char value[3] = { 'Z', c, '\0' };
+    static std::string format() { return std::string(value); }
+};
+
+#ifndef PYBIND11_CPP17
+
+template <typename T> constexpr const char format_descriptor<
+    std::complex<T>, detail::enable_if_t<std::is_floating_point<T>::value>>::value[3];
+
+#endif
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+template <typename T> struct is_fmt_numeric<std::complex<T>, detail::enable_if_t<std::is_floating_point<T>::value>> {
     static constexpr bool value = true;
     static constexpr int index = is_fmt_numeric<T>::index + 3;
 };
@@ -48,5 +61,5 @@ template <typename T> class type_caster<std::complex<T>> {
 
     PYBIND11_TYPE_CASTER(std::complex<T>, _("complex"));
 };
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/descr.h b/libs/pybind/pybind11/descr.h
deleted file mode 100644
index 2c3fb3d135..0000000000
--- a/libs/pybind/pybind11/descr.h
+++ /dev/null
@@ -1,183 +0,0 @@
-/*
-    pybind11/descr.h: Helper type for concatenating type signatures
-    either at runtime (C++11) or compile time (C++14)
-
-    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
-
-    All rights reserved. Use of this source code is governed by a
-    BSD-style license that can be found in the LICENSE file.
-*/
-
-#pragma once
-
-#include "common.h"
-
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
-
-#if defined(PYBIND11_CPP14) /* Concatenate type signatures at compile time using C++14 */
-
-template <size_t Size1, size_t Size2> class descr {
-    template <size_t Size1_, size_t Size2_> friend class descr;
-public:
-    constexpr descr(char const (&text) [Size1+1], const std::type_info * const (&types)[Size2+1])
-        : descr(text, types,
-                make_index_sequence<Size1>(),
-                make_index_sequence<Size2>()) { }
-
-    constexpr const char *text() const { return m_text; }
-    constexpr const std::type_info * const * types() const { return m_types; }
-
-    template <size_t OtherSize1, size_t OtherSize2>
-    constexpr descr<Size1 + OtherSize1, Size2 + OtherSize2> operator+(const descr<OtherSize1, OtherSize2> &other) const {
-        return concat(other,
-                      make_index_sequence<Size1>(),
-                      make_index_sequence<Size2>(),
-                      make_index_sequence<OtherSize1>(),
-                      make_index_sequence<OtherSize2>());
-    }
-
-protected:
-    template <size_t... Indices1, size_t... Indices2>
-    constexpr descr(
-        char const (&text) [Size1+1],
-        const std::type_info * const (&types) [Size2+1],
-        index_sequence<Indices1...>, index_sequence<Indices2...>)
-        : m_text{text[Indices1]..., '\0'},
-          m_types{types[Indices2]...,  nullptr } {}
-
-    template <size_t OtherSize1, size_t OtherSize2, size_t... Indices1,
-              size_t... Indices2, size_t... OtherIndices1, size_t... OtherIndices2>
-    constexpr descr<Size1 + OtherSize1, Size2 + OtherSize2>
-    concat(const descr<OtherSize1, OtherSize2> &other,
-           index_sequence<Indices1...>, index_sequence<Indices2...>,
-           index_sequence<OtherIndices1...>, index_sequence<OtherIndices2...>) const {
-        return descr<Size1 + OtherSize1, Size2 + OtherSize2>(
-            { m_text[Indices1]..., other.m_text[OtherIndices1]..., '\0' },
-            { m_types[Indices2]..., other.m_types[OtherIndices2]..., nullptr }
-        );
-    }
-
-protected:
-    char m_text[Size1 + 1];
-    const std::type_info * m_types[Size2 + 1];
-};
-
-template <size_t Size> constexpr descr<Size - 1, 0> _(char const(&text)[Size]) {
-    return descr<Size - 1, 0>(text, { nullptr });
-}
-
-template <size_t Rem, size_t... Digits> struct int_to_str : int_to_str<Rem/10, Rem%10, Digits...> { };
-template <size_t...Digits> struct int_to_str<0, Digits...> {
-    static constexpr auto digits = descr<sizeof...(Digits), 0>({ ('0' + Digits)..., '\0' }, { nullptr });
-};
-
-// Ternary description (like std::conditional)
-template <bool B, size_t Size1, size_t Size2>
-constexpr enable_if_t<B, descr<Size1 - 1, 0>> _(char const(&text1)[Size1], char const(&)[Size2]) {
-    return _(text1);
-}
-template <bool B, size_t Size1, size_t Size2>
-constexpr enable_if_t<!B, descr<Size2 - 1, 0>> _(char const(&)[Size1], char const(&text2)[Size2]) {
-    return _(text2);
-}
-template <bool B, size_t SizeA1, size_t SizeA2, size_t SizeB1, size_t SizeB2>
-constexpr enable_if_t<B, descr<SizeA1, SizeA2>> _(descr<SizeA1, SizeA2> d, descr<SizeB1, SizeB2>) { return d; }
-template <bool B, size_t SizeA1, size_t SizeA2, size_t SizeB1, size_t SizeB2>
-constexpr enable_if_t<!B, descr<SizeB1, SizeB2>> _(descr<SizeA1, SizeA2>, descr<SizeB1, SizeB2> d) { return d; }
-
-template <size_t Size> auto constexpr _() -> decltype(int_to_str<Size / 10, Size % 10>::digits) {
-    return int_to_str<Size / 10, Size % 10>::digits;
-}
-
-template <typename Type> constexpr descr<1, 1> _() {
-    return descr<1, 1>({ '%', '\0' }, { &typeid(Type), nullptr });
-}
-
-inline constexpr descr<0, 0> concat() { return _(""); }
-template <size_t Size1, size_t Size2, typename... Args> auto constexpr concat(descr<Size1, Size2> descr) { return descr; }
-template <size_t Size1, size_t Size2, typename... Args> auto constexpr concat(descr<Size1, Size2> descr, Args&&... args) { return descr + _(", ") + concat(args...); }
-template <size_t Size1, size_t Size2> auto constexpr type_descr(descr<Size1, Size2> descr) { return _("{") + descr + _("}"); }
-
-#define PYBIND11_DESCR constexpr auto
-
-#else /* Simpler C++11 implementation based on run-time memory allocation and copying */
-
-class descr {
-public:
-    PYBIND11_NOINLINE descr(const char *text, const std::type_info * const * types) {
-        size_t nChars = len(text), nTypes = len(types);
-        m_text  = new char[nChars];
-        m_types = new const std::type_info *[nTypes];
-        memcpy(m_text, text, nChars * sizeof(char));
-        memcpy(m_types, types, nTypes * sizeof(const std::type_info *));
-    }
-
-    PYBIND11_NOINLINE descr friend operator+(descr &&d1, descr &&d2) {
-        descr r;
-
-        size_t nChars1 = len(d1.m_text), nTypes1 = len(d1.m_types);
-        size_t nChars2 = len(d2.m_text), nTypes2 = len(d2.m_types);
-
-        r.m_text  = new char[nChars1 + nChars2 - 1];
-        r.m_types = new const std::type_info *[nTypes1 + nTypes2 - 1];
-        memcpy(r.m_text, d1.m_text, (nChars1-1) * sizeof(char));
-        memcpy(r.m_text + nChars1 - 1, d2.m_text, nChars2 * sizeof(char));
-        memcpy(r.m_types, d1.m_types, (nTypes1-1) * sizeof(std::type_info *));
-        memcpy(r.m_types + nTypes1 - 1, d2.m_types, nTypes2 * sizeof(std::type_info *));
-
-        delete[] d1.m_text; delete[] d1.m_types;
-        delete[] d2.m_text; delete[] d2.m_types;
-
-        return r;
-    }
-
-    char *text() { return m_text; }
-    const std::type_info * * types() { return m_types; }
-
-protected:
-    PYBIND11_NOINLINE descr() { }
-
-    template <typename T> static size_t len(const T *ptr) { // return length including null termination
-        const T *it = ptr;
-        while (*it++ != (T) 0)
-            ;
-        return static_cast<size_t>(it - ptr);
-    }
-
-    const std::type_info **m_types = nullptr;
-    char *m_text = nullptr;
-};
-
-/* The 'PYBIND11_NOINLINE inline' combinations below are intentional to get the desired linkage while producing as little object code as possible */
-
-PYBIND11_NOINLINE inline descr _(const char *text) {
-    const std::type_info *types[1] = { nullptr };
-    return descr(text, types);
-}
-
-template <bool B> PYBIND11_NOINLINE enable_if_t<B, descr> _(const char *text1, const char *) { return _(text1); }
-template <bool B> PYBIND11_NOINLINE enable_if_t<!B, descr> _(char const *, const char *text2) { return _(text2); }
-template <bool B> PYBIND11_NOINLINE enable_if_t<B, descr> _(descr d, descr) { return d; }
-template <bool B> PYBIND11_NOINLINE enable_if_t<!B, descr> _(descr, descr d) { return d; }
-
-template <typename Type> PYBIND11_NOINLINE descr _() {
-    const std::type_info *types[2] = { &typeid(Type), nullptr };
-    return descr("%", types);
-}
-
-template <size_t Size> PYBIND11_NOINLINE descr _() {
-    const std::type_info *types[1] = { nullptr };
-    return descr(std::to_string(Size).c_str(), types);
-}
-
-PYBIND11_NOINLINE inline descr concat() { return _(""); }
-PYBIND11_NOINLINE inline descr concat(descr &&d) { return d; }
-template <typename... Args> PYBIND11_NOINLINE descr concat(descr &&d, Args&&... args) { return std::move(d) + _(", ") + concat(std::forward<Args>(args)...); }
-PYBIND11_NOINLINE inline descr type_descr(descr&& d) { return _("{") + std::move(d) + _("}"); }
-
-#define PYBIND11_DESCR ::pybind11::detail::descr
-#endif
-
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
diff --git a/libs/pybind/pybind11/detail/class.h b/libs/pybind/pybind11/detail/class.h
new file mode 100644
index 0000000000..65dad5a57e
--- /dev/null
+++ b/libs/pybind/pybind11/detail/class.h
@@ -0,0 +1,710 @@
+/*
+    pybind11/detail/class.h: Python C API implementation details for py::class_
+
+    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "../attr.h"
+#include "../options.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+#if PY_VERSION_HEX >= 0x03030000 && !defined(PYPY_VERSION)
+#  define PYBIND11_BUILTIN_QUALNAME
+#  define PYBIND11_SET_OLDPY_QUALNAME(obj, nameobj)
+#else
+// In pre-3.3 Python, we still set __qualname__ so that we can produce reliable function type
+// signatures; in 3.3+ this macro expands to nothing:
+#  define PYBIND11_SET_OLDPY_QUALNAME(obj, nameobj) setattr((PyObject *) obj, "__qualname__", nameobj)
+#endif
+
+inline std::string get_fully_qualified_tp_name(PyTypeObject *type) {
+#if !defined(PYPY_VERSION)
+    return type->tp_name;
+#else
+    auto module_name = handle((PyObject *) type).attr("__module__").cast<std::string>();
+    if (module_name == PYBIND11_BUILTINS_MODULE)
+        return type->tp_name;
+    else
+        return std::move(module_name) + "." + type->tp_name;
+#endif
+}
+
+inline PyTypeObject *type_incref(PyTypeObject *type) {
+    Py_INCREF(type);
+    return type;
+}
+
+#if !defined(PYPY_VERSION)
+
+/// `pybind11_static_property.__get__()`: Always pass the class instead of the instance.
+extern "C" inline PyObject *pybind11_static_get(PyObject *self, PyObject * /*ob*/, PyObject *cls) {
+    return PyProperty_Type.tp_descr_get(self, cls, cls);
+}
+
+/// `pybind11_static_property.__set__()`: Just like the above `__get__()`.
+extern "C" inline int pybind11_static_set(PyObject *self, PyObject *obj, PyObject *value) {
+    PyObject *cls = PyType_Check(obj) ? obj : (PyObject *) Py_TYPE(obj);
+    return PyProperty_Type.tp_descr_set(self, cls, value);
+}
+
+/** A `static_property` is the same as a `property` but the `__get__()` and `__set__()`
+    methods are modified to always use the object type instead of a concrete instance.
+    Return value: New reference. */
+inline PyTypeObject *make_static_property_type() {
+    constexpr auto *name = "pybind11_static_property";
+    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
+
+    /* Danger zone: from now (and until PyType_Ready), make sure to
+       issue no Python C API calls which could potentially invoke the
+       garbage collector (the GC will call type_traverse(), which will in
+       turn find the newly constructed type in an invalid state) */
+    auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
+    if (!heap_type)
+        pybind11_fail("make_static_property_type(): error allocating type!");
+
+    heap_type->ht_name = name_obj.inc_ref().ptr();
+#ifdef PYBIND11_BUILTIN_QUALNAME
+    heap_type->ht_qualname = name_obj.inc_ref().ptr();
+#endif
+
+    auto type = &heap_type->ht_type;
+    type->tp_name = name;
+    type->tp_base = type_incref(&PyProperty_Type);
+    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
+    type->tp_descr_get = pybind11_static_get;
+    type->tp_descr_set = pybind11_static_set;
+
+    if (PyType_Ready(type) < 0)
+        pybind11_fail("make_static_property_type(): failure in PyType_Ready()!");
+
+    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
+    PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
+
+    return type;
+}
+
+#else // PYPY
+
+/** PyPy has some issues with the above C API, so we evaluate Python code instead.
+    This function will only be called once so performance isn't really a concern.
+    Return value: New reference. */
+inline PyTypeObject *make_static_property_type() {
+    auto d = dict();
+    PyObject *result = PyRun_String(R"(\
+        class pybind11_static_property(property):
+            def __get__(self, obj, cls):
+                return property.__get__(self, cls, cls)
+
+            def __set__(self, obj, value):
+                cls = obj if isinstance(obj, type) else type(obj)
+                property.__set__(self, cls, value)
+        )", Py_file_input, d.ptr(), d.ptr()
+    );
+    if (result == nullptr)
+        throw error_already_set();
+    Py_DECREF(result);
+    return (PyTypeObject *) d["pybind11_static_property"].cast<object>().release().ptr();
+}
+
+#endif // PYPY
+
+/** Types with static properties need to handle `Type.static_prop = x` in a specific way.
+    By default, Python replaces the `static_property` itself, but for wrapped C++ types
+    we need to call `static_property.__set__()` in order to propagate the new value to
+    the underlying C++ data structure. */
+extern "C" inline int pybind11_meta_setattro(PyObject* obj, PyObject* name, PyObject* value) {
+    // Use `_PyType_Lookup()` instead of `PyObject_GetAttr()` in order to get the raw
+    // descriptor (`property`) instead of calling `tp_descr_get` (`property.__get__()`).
+    PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
+
+    // The following assignment combinations are possible:
+    //   1. `Type.static_prop = value`             --> descr_set: `Type.static_prop.__set__(value)`
+    //   2. `Type.static_prop = other_static_prop` --> setattro:  replace existing `static_prop`
+    //   3. `Type.regular_attribute = value`       --> setattro:  regular attribute assignment
+    const auto static_prop = (PyObject *) get_internals().static_property_type;
+    const auto call_descr_set = descr && value && PyObject_IsInstance(descr, static_prop)
+                                && !PyObject_IsInstance(value, static_prop);
+    if (call_descr_set) {
+        // Call `static_property.__set__()` instead of replacing the `static_property`.
+#if !defined(PYPY_VERSION)
+        return Py_TYPE(descr)->tp_descr_set(descr, obj, value);
+#else
+        if (PyObject *result = PyObject_CallMethod(descr, "__set__", "OO", obj, value)) {
+            Py_DECREF(result);
+            return 0;
+        } else {
+            return -1;
+        }
+#endif
+    } else {
+        // Replace existing attribute.
+        return PyType_Type.tp_setattro(obj, name, value);
+    }
+}
+
+#if PY_MAJOR_VERSION >= 3
+/**
+ * Python 3's PyInstanceMethod_Type hides itself via its tp_descr_get, which prevents aliasing
+ * methods via cls.attr("m2") = cls.attr("m1"): instead the tp_descr_get returns a plain function,
+ * when called on a class, or a PyMethod, when called on an instance.  Override that behaviour here
+ * to do a special case bypass for PyInstanceMethod_Types.
+ */
+extern "C" inline PyObject *pybind11_meta_getattro(PyObject *obj, PyObject *name) {
+    PyObject *descr = _PyType_Lookup((PyTypeObject *) obj, name);
+    if (descr && PyInstanceMethod_Check(descr)) {
+        Py_INCREF(descr);
+        return descr;
+    }
+    else {
+        return PyType_Type.tp_getattro(obj, name);
+    }
+}
+#endif
+
+/// metaclass `__call__` function that is used to create all pybind11 objects.
+extern "C" inline PyObject *pybind11_meta_call(PyObject *type, PyObject *args, PyObject *kwargs) {
+
+    // use the default metaclass call to create/initialize the object
+    PyObject *self = PyType_Type.tp_call(type, args, kwargs);
+    if (self == nullptr) {
+        return nullptr;
+    }
+
+    // This must be a pybind11 instance
+    auto instance = reinterpret_cast<detail::instance *>(self);
+
+    // Ensure that the base __init__ function(s) were called
+    for (const auto &vh : values_and_holders(instance)) {
+        if (!vh.holder_constructed()) {
+            PyErr_Format(PyExc_TypeError, "%.200s.__init__() must be called when overriding __init__",
+                         get_fully_qualified_tp_name(vh.type->type).c_str());
+            Py_DECREF(self);
+            return nullptr;
+        }
+    }
+
+    return self;
+}
+
+/// Cleanup the type-info for a pybind11-registered type.
+extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
+    auto *type = (PyTypeObject *) obj;
+    auto &internals = get_internals();
+
+    // A pybind11-registered type will:
+    // 1) be found in internals.registered_types_py
+    // 2) have exactly one associated `detail::type_info`
+    auto found_type = internals.registered_types_py.find(type);
+    if (found_type != internals.registered_types_py.end() &&
+        found_type->second.size() == 1 &&
+        found_type->second[0]->type == type) {
+
+        auto *tinfo = found_type->second[0];
+        auto tindex = std::type_index(*tinfo->cpptype);
+        internals.direct_conversions.erase(tindex);
+
+        if (tinfo->module_local)
+            registered_local_types_cpp().erase(tindex);
+        else
+            internals.registered_types_cpp.erase(tindex);
+        internals.registered_types_py.erase(tinfo->type);
+
+        // Actually just `std::erase_if`, but that's only available in C++20
+        auto &cache = internals.inactive_override_cache;
+        for (auto it = cache.begin(), last = cache.end(); it != last; ) {
+            if (it->first == (PyObject *) tinfo->type)
+                it = cache.erase(it);
+            else
+                ++it;
+        }
+
+        delete tinfo;
+    }
+
+    PyType_Type.tp_dealloc(obj);
+}
+
+/** This metaclass is assigned by default to all pybind11 types and is required in order
+    for static properties to function correctly. Users may override this using `py::metaclass`.
+    Return value: New reference. */
+inline PyTypeObject* make_default_metaclass() {
+    constexpr auto *name = "pybind11_type";
+    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
+
+    /* Danger zone: from now (and until PyType_Ready), make sure to
+       issue no Python C API calls which could potentially invoke the
+       garbage collector (the GC will call type_traverse(), which will in
+       turn find the newly constructed type in an invalid state) */
+    auto heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
+    if (!heap_type)
+        pybind11_fail("make_default_metaclass(): error allocating metaclass!");
+
+    heap_type->ht_name = name_obj.inc_ref().ptr();
+#ifdef PYBIND11_BUILTIN_QUALNAME
+    heap_type->ht_qualname = name_obj.inc_ref().ptr();
+#endif
+
+    auto type = &heap_type->ht_type;
+    type->tp_name = name;
+    type->tp_base = type_incref(&PyType_Type);
+    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
+
+    type->tp_call = pybind11_meta_call;
+
+    type->tp_setattro = pybind11_meta_setattro;
+#if PY_MAJOR_VERSION >= 3
+    type->tp_getattro = pybind11_meta_getattro;
+#endif
+
+    type->tp_dealloc = pybind11_meta_dealloc;
+
+    if (PyType_Ready(type) < 0)
+        pybind11_fail("make_default_metaclass(): failure in PyType_Ready()!");
+
+    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
+    PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
+
+    return type;
+}
+
+/// For multiple inheritance types we need to recursively register/deregister base pointers for any
+/// base classes with pointers that are difference from the instance value pointer so that we can
+/// correctly recognize an offset base class pointer. This calls a function with any offset base ptrs.
+inline void traverse_offset_bases(void *valueptr, const detail::type_info *tinfo, instance *self,
+        bool (*f)(void * /*parentptr*/, instance * /*self*/)) {
+    for (handle h : reinterpret_borrow<tuple>(tinfo->type->tp_bases)) {
+        if (auto parent_tinfo = get_type_info((PyTypeObject *) h.ptr())) {
+            for (auto &c : parent_tinfo->implicit_casts) {
+                if (c.first == tinfo->cpptype) {
+                    auto *parentptr = c.second(valueptr);
+                    if (parentptr != valueptr)
+                        f(parentptr, self);
+                    traverse_offset_bases(parentptr, parent_tinfo, self, f);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+inline bool register_instance_impl(void *ptr, instance *self) {
+    get_internals().registered_instances.emplace(ptr, self);
+    return true; // unused, but gives the same signature as the deregister func
+}
+inline bool deregister_instance_impl(void *ptr, instance *self) {
+    auto &registered_instances = get_internals().registered_instances;
+    auto range = registered_instances.equal_range(ptr);
+    for (auto it = range.first; it != range.second; ++it) {
+        if (self == it->second) {
+            registered_instances.erase(it);
+            return true;
+        }
+    }
+    return false;
+}
+
+inline void register_instance(instance *self, void *valptr, const type_info *tinfo) {
+    register_instance_impl(valptr, self);
+    if (!tinfo->simple_ancestors)
+        traverse_offset_bases(valptr, tinfo, self, register_instance_impl);
+}
+
+inline bool deregister_instance(instance *self, void *valptr, const type_info *tinfo) {
+    bool ret = deregister_instance_impl(valptr, self);
+    if (!tinfo->simple_ancestors)
+        traverse_offset_bases(valptr, tinfo, self, deregister_instance_impl);
+    return ret;
+}
+
+/// Instance creation function for all pybind11 types. It allocates the internal instance layout for
+/// holding C++ objects and holders.  Allocation is done lazily (the first time the instance is cast
+/// to a reference or pointer), and initialization is done by an `__init__` function.
+inline PyObject *make_new_instance(PyTypeObject *type) {
+#if defined(PYPY_VERSION)
+    // PyPy gets tp_basicsize wrong (issue 2482) under multiple inheritance when the first inherited
+    // object is a a plain Python type (i.e. not derived from an extension type).  Fix it.
+    ssize_t instance_size = static_cast<ssize_t>(sizeof(instance));
+    if (type->tp_basicsize < instance_size) {
+        type->tp_basicsize = instance_size;
+    }
+#endif
+    PyObject *self = type->tp_alloc(type, 0);
+    auto inst = reinterpret_cast<instance *>(self);
+    // Allocate the value/holder internals:
+    inst->allocate_layout();
+
+    inst->owned = true;
+
+    return self;
+}
+
+/// Instance creation function for all pybind11 types. It only allocates space for the
+/// C++ object, but doesn't call the constructor -- an `__init__` function must do that.
+extern "C" inline PyObject *pybind11_object_new(PyTypeObject *type, PyObject *, PyObject *) {
+    return make_new_instance(type);
+}
+
+/// An `__init__` function constructs the C++ object. Users should provide at least one
+/// of these using `py::init` or directly with `.def(__init__, ...)`. Otherwise, the
+/// following default function will be used which simply throws an exception.
+extern "C" inline int pybind11_object_init(PyObject *self, PyObject *, PyObject *) {
+    PyTypeObject *type = Py_TYPE(self);
+    std::string msg = get_fully_qualified_tp_name(type) + ": No constructor defined!";
+    PyErr_SetString(PyExc_TypeError, msg.c_str());
+    return -1;
+}
+
+inline void add_patient(PyObject *nurse, PyObject *patient) {
+    auto &internals = get_internals();
+    auto instance = reinterpret_cast<detail::instance *>(nurse);
+    instance->has_patients = true;
+    Py_INCREF(patient);
+    internals.patients[nurse].push_back(patient);
+}
+
+inline void clear_patients(PyObject *self) {
+    auto instance = reinterpret_cast<detail::instance *>(self);
+    auto &internals = get_internals();
+    auto pos = internals.patients.find(self);
+    assert(pos != internals.patients.end());
+    // Clearing the patients can cause more Python code to run, which
+    // can invalidate the iterator. Extract the vector of patients
+    // from the unordered_map first.
+    auto patients = std::move(pos->second);
+    internals.patients.erase(pos);
+    instance->has_patients = false;
+    for (PyObject *&patient : patients)
+        Py_CLEAR(patient);
+}
+
+/// Clears all internal data from the instance and removes it from registered instances in
+/// preparation for deallocation.
+inline void clear_instance(PyObject *self) {
+    auto instance = reinterpret_cast<detail::instance *>(self);
+
+    // Deallocate any values/holders, if present:
+    for (auto &v_h : values_and_holders(instance)) {
+        if (v_h) {
+
+            // We have to deregister before we call dealloc because, for virtual MI types, we still
+            // need to be able to get the parent pointers.
+            if (v_h.instance_registered() && !deregister_instance(instance, v_h.value_ptr(), v_h.type))
+                pybind11_fail("pybind11_object_dealloc(): Tried to deallocate unregistered instance!");
+
+            if (instance->owned || v_h.holder_constructed())
+                v_h.type->dealloc(v_h);
+        }
+    }
+    // Deallocate the value/holder layout internals:
+    instance->deallocate_layout();
+
+    if (instance->weakrefs)
+        PyObject_ClearWeakRefs(self);
+
+    PyObject **dict_ptr = _PyObject_GetDictPtr(self);
+    if (dict_ptr)
+        Py_CLEAR(*dict_ptr);
+
+    if (instance->has_patients)
+        clear_patients(self);
+}
+
+/// Instance destructor function for all pybind11 types. It calls `type_info.dealloc`
+/// to destroy the C++ object itself, while the rest is Python bookkeeping.
+extern "C" inline void pybind11_object_dealloc(PyObject *self) {
+    clear_instance(self);
+
+    auto type = Py_TYPE(self);
+    type->tp_free(self);
+
+#if PY_VERSION_HEX < 0x03080000
+    // `type->tp_dealloc != pybind11_object_dealloc` means that we're being called
+    // as part of a derived type's dealloc, in which case we're not allowed to decref
+    // the type here. For cross-module compatibility, we shouldn't compare directly
+    // with `pybind11_object_dealloc`, but with the common one stashed in internals.
+    auto pybind11_object_type = (PyTypeObject *) get_internals().instance_base;
+    if (type->tp_dealloc == pybind11_object_type->tp_dealloc)
+        Py_DECREF(type);
+#else
+    // This was not needed before Python 3.8 (Python issue 35810)
+    // https://github.com/pybind/pybind11/issues/1946
+    Py_DECREF(type);
+#endif
+}
+
+/** Create the type which can be used as a common base for all classes.  This is
+    needed in order to satisfy Python's requirements for multiple inheritance.
+    Return value: New reference. */
+inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
+    constexpr auto *name = "pybind11_object";
+    auto name_obj = reinterpret_steal<object>(PYBIND11_FROM_STRING(name));
+
+    /* Danger zone: from now (and until PyType_Ready), make sure to
+       issue no Python C API calls which could potentially invoke the
+       garbage collector (the GC will call type_traverse(), which will in
+       turn find the newly constructed type in an invalid state) */
+    auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
+    if (!heap_type)
+        pybind11_fail("make_object_base_type(): error allocating type!");
+
+    heap_type->ht_name = name_obj.inc_ref().ptr();
+#ifdef PYBIND11_BUILTIN_QUALNAME
+    heap_type->ht_qualname = name_obj.inc_ref().ptr();
+#endif
+
+    auto type = &heap_type->ht_type;
+    type->tp_name = name;
+    type->tp_base = type_incref(&PyBaseObject_Type);
+    type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
+    type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HEAPTYPE;
+
+    type->tp_new = pybind11_object_new;
+    type->tp_init = pybind11_object_init;
+    type->tp_dealloc = pybind11_object_dealloc;
+
+    /* Support weak references (needed for the keep_alive feature) */
+    type->tp_weaklistoffset = offsetof(instance, weakrefs);
+
+    if (PyType_Ready(type) < 0)
+        pybind11_fail("PyType_Ready failed in make_object_base_type():" + error_string());
+
+    setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
+    PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
+
+    assert(!PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
+    return (PyObject *) heap_type;
+}
+
+/// dynamic_attr: Support for `d = instance.__dict__`.
+extern "C" inline PyObject *pybind11_get_dict(PyObject *self, void *) {
+    PyObject *&dict = *_PyObject_GetDictPtr(self);
+    if (!dict)
+        dict = PyDict_New();
+    Py_XINCREF(dict);
+    return dict;
+}
+
+/// dynamic_attr: Support for `instance.__dict__ = dict()`.
+extern "C" inline int pybind11_set_dict(PyObject *self, PyObject *new_dict, void *) {
+    if (!PyDict_Check(new_dict)) {
+        PyErr_Format(PyExc_TypeError, "__dict__ must be set to a dictionary, not a '%.200s'",
+                     get_fully_qualified_tp_name(Py_TYPE(new_dict)).c_str());
+        return -1;
+    }
+    PyObject *&dict = *_PyObject_GetDictPtr(self);
+    Py_INCREF(new_dict);
+    Py_CLEAR(dict);
+    dict = new_dict;
+    return 0;
+}
+
+/// dynamic_attr: Allow the garbage collector to traverse the internal instance `__dict__`.
+extern "C" inline int pybind11_traverse(PyObject *self, visitproc visit, void *arg) {
+    PyObject *&dict = *_PyObject_GetDictPtr(self);
+    Py_VISIT(dict);
+    return 0;
+}
+
+/// dynamic_attr: Allow the GC to clear the dictionary.
+extern "C" inline int pybind11_clear(PyObject *self) {
+    PyObject *&dict = *_PyObject_GetDictPtr(self);
+    Py_CLEAR(dict);
+    return 0;
+}
+
+/// Give instances of this type a `__dict__` and opt into garbage collection.
+inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
+    auto type = &heap_type->ht_type;
+    type->tp_flags |= Py_TPFLAGS_HAVE_GC;
+    type->tp_dictoffset = type->tp_basicsize; // place dict at the end
+    type->tp_basicsize += (ssize_t)sizeof(PyObject *); // and allocate enough space for it
+    type->tp_traverse = pybind11_traverse;
+    type->tp_clear = pybind11_clear;
+
+    static PyGetSetDef getset[] = {
+        {const_cast<char*>("__dict__"), pybind11_get_dict, pybind11_set_dict, nullptr, nullptr},
+        {nullptr, nullptr, nullptr, nullptr, nullptr}
+    };
+    type->tp_getset = getset;
+}
+
+/// buffer_protocol: Fill in the view as specified by flags.
+extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int flags) {
+    // Look for a `get_buffer` implementation in this type's info or any bases (following MRO).
+    type_info *tinfo = nullptr;
+    for (auto type : reinterpret_borrow<tuple>(Py_TYPE(obj)->tp_mro)) {
+        tinfo = get_type_info((PyTypeObject *) type.ptr());
+        if (tinfo && tinfo->get_buffer)
+            break;
+    }
+    if (view == nullptr || !tinfo || !tinfo->get_buffer) {
+        if (view)
+            view->obj = nullptr;
+        PyErr_SetString(PyExc_BufferError, "pybind11_getbuffer(): Internal error");
+        return -1;
+    }
+    std::memset(view, 0, sizeof(Py_buffer));
+    buffer_info *info = tinfo->get_buffer(obj, tinfo->get_buffer_data);
+    view->obj = obj;
+    view->ndim = 1;
+    view->internal = info;
+    view->buf = info->ptr;
+    view->itemsize = info->itemsize;
+    view->len = view->itemsize;
+    for (auto s : info->shape)
+        view->len *= s;
+    view->readonly = info->readonly;
+    if ((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE && info->readonly) {
+        if (view)
+            view->obj = nullptr;
+        PyErr_SetString(PyExc_BufferError, "Writable buffer requested for readonly storage");
+        return -1;
+    }
+    if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT)
+        view->format = const_cast<char *>(info->format.c_str());
+    if ((flags & PyBUF_STRIDES) == PyBUF_STRIDES) {
+        view->ndim = (int) info->ndim;
+        view->strides = &info->strides[0];
+        view->shape = &info->shape[0];
+    }
+    Py_INCREF(view->obj);
+    return 0;
+}
+
+/// buffer_protocol: Release the resources of the buffer.
+extern "C" inline void pybind11_releasebuffer(PyObject *, Py_buffer *view) {
+    delete (buffer_info *) view->internal;
+}
+
+/// Give this type a buffer interface.
+inline void enable_buffer_protocol(PyHeapTypeObject *heap_type) {
+    heap_type->ht_type.tp_as_buffer = &heap_type->as_buffer;
+#if PY_MAJOR_VERSION < 3
+    heap_type->ht_type.tp_flags |= Py_TPFLAGS_HAVE_NEWBUFFER;
+#endif
+
+    heap_type->as_buffer.bf_getbuffer = pybind11_getbuffer;
+    heap_type->as_buffer.bf_releasebuffer = pybind11_releasebuffer;
+}
+
+/** Create a brand new Python type according to the `type_record` specification.
+    Return value: New reference. */
+inline PyObject* make_new_python_type(const type_record &rec) {
+    auto name = reinterpret_steal<object>(PYBIND11_FROM_STRING(rec.name));
+
+    auto qualname = name;
+    if (rec.scope && !PyModule_Check(rec.scope.ptr()) && hasattr(rec.scope, "__qualname__")) {
+#if PY_MAJOR_VERSION >= 3
+        qualname = reinterpret_steal<object>(
+            PyUnicode_FromFormat("%U.%U", rec.scope.attr("__qualname__").ptr(), name.ptr()));
+#else
+        qualname = str(rec.scope.attr("__qualname__").cast<std::string>() + "." + rec.name);
+#endif
+    }
+
+    object module_;
+    if (rec.scope) {
+        if (hasattr(rec.scope, "__module__"))
+            module_ = rec.scope.attr("__module__");
+        else if (hasattr(rec.scope, "__name__"))
+            module_ = rec.scope.attr("__name__");
+    }
+
+    auto full_name = c_str(
+#if !defined(PYPY_VERSION)
+        module_ ? str(module_).cast<std::string>() + "." + rec.name :
+#endif
+        rec.name);
+
+    char *tp_doc = nullptr;
+    if (rec.doc && options::show_user_defined_docstrings()) {
+        /* Allocate memory for docstring (using PyObject_MALLOC, since
+           Python will free this later on) */
+        size_t size = strlen(rec.doc) + 1;
+        tp_doc = (char *) PyObject_MALLOC(size);
+        memcpy((void *) tp_doc, rec.doc, size);
+    }
+
+    auto &internals = get_internals();
+    auto bases = tuple(rec.bases);
+    auto base = (bases.empty()) ? internals.instance_base
+                                    : bases[0].ptr();
+
+    /* Danger zone: from now (and until PyType_Ready), make sure to
+       issue no Python C API calls which could potentially invoke the
+       garbage collector (the GC will call type_traverse(), which will in
+       turn find the newly constructed type in an invalid state) */
+    auto metaclass = rec.metaclass.ptr() ? (PyTypeObject *) rec.metaclass.ptr()
+                                         : internals.default_metaclass;
+
+    auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
+    if (!heap_type)
+        pybind11_fail(std::string(rec.name) + ": Unable to create type object!");
+
+    heap_type->ht_name = name.release().ptr();
+#ifdef PYBIND11_BUILTIN_QUALNAME
+    heap_type->ht_qualname = qualname.inc_ref().ptr();
+#endif
+
+    auto type = &heap_type->ht_type;
+    type->tp_name = full_name;
+    type->tp_doc = tp_doc;
+    type->tp_base = type_incref((PyTypeObject *)base);
+    type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
+    if (!bases.empty())
+        type->tp_bases = bases.release().ptr();
+
+    /* Don't inherit base __init__ */
+    type->tp_init = pybind11_object_init;
+
+    /* Supported protocols */
+    type->tp_as_number = &heap_type->as_number;
+    type->tp_as_sequence = &heap_type->as_sequence;
+    type->tp_as_mapping = &heap_type->as_mapping;
+#if PY_VERSION_HEX >= 0x03050000
+    type->tp_as_async = &heap_type->as_async;
+#endif
+
+    /* Flags */
+    type->tp_flags |= Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE;
+#if PY_MAJOR_VERSION < 3
+    type->tp_flags |= Py_TPFLAGS_CHECKTYPES;
+#endif
+    if (!rec.is_final)
+        type->tp_flags |= Py_TPFLAGS_BASETYPE;
+
+    if (rec.dynamic_attr)
+        enable_dynamic_attributes(heap_type);
+
+    if (rec.buffer_protocol)
+        enable_buffer_protocol(heap_type);
+
+    if (PyType_Ready(type) < 0)
+        pybind11_fail(std::string(rec.name) + ": PyType_Ready failed (" + error_string() + ")!");
+
+    assert(rec.dynamic_attr ? PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC)
+                            : !PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
+
+    /* Register type with the parent scope */
+    if (rec.scope)
+        setattr(rec.scope, rec.name, (PyObject *) type);
+    else
+        Py_INCREF(type); // Keep it alive forever (reference leak)
+
+    if (module_) // Needed by pydoc
+        setattr((PyObject *) type, "__module__", module_);
+
+    PYBIND11_SET_OLDPY_QUALNAME(type, qualname);
+
+    return (PyObject *) type;
+}
+
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/detail/common.h b/libs/pybind/pybind11/detail/common.h
new file mode 100644
index 0000000000..751141a927
--- /dev/null
+++ b/libs/pybind/pybind11/detail/common.h
@@ -0,0 +1,853 @@
+/*
+    pybind11/detail/common.h -- Basic macros
+
+    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#define PYBIND11_VERSION_MAJOR 2
+#define PYBIND11_VERSION_MINOR 6
+#define PYBIND11_VERSION_PATCH 1
+
+#define PYBIND11_NAMESPACE_BEGIN(name) namespace name {
+#define PYBIND11_NAMESPACE_END(name) }
+
+// Robust support for some features and loading modules compiled against different pybind versions
+// requires forcing hidden visibility on pybind code, so we enforce this by setting the attribute on
+// the main `pybind11` namespace.
+#if !defined(PYBIND11_NAMESPACE)
+#  ifdef __GNUG__
+#    define PYBIND11_NAMESPACE pybind11 __attribute__((visibility("hidden")))
+#  else
+#    define PYBIND11_NAMESPACE pybind11
+#  endif
+#endif
+
+#if !(defined(_MSC_VER) && __cplusplus == 199711L) && !defined(__INTEL_COMPILER)
+#  if __cplusplus >= 201402L
+#    define PYBIND11_CPP14
+#    if __cplusplus >= 201703L
+#      define PYBIND11_CPP17
+#    endif
+#  endif
+#elif defined(_MSC_VER) && __cplusplus == 199711L
+// MSVC sets _MSVC_LANG rather than __cplusplus (supposedly until the standard is fully implemented)
+// Unless you use the /Zc:__cplusplus flag on Visual Studio 2017 15.7 Preview 3 or newer
+#  if _MSVC_LANG >= 201402L
+#    define PYBIND11_CPP14
+#    if _MSVC_LANG > 201402L && _MSC_VER >= 1910
+#      define PYBIND11_CPP17
+#    endif
+#  endif
+#endif
+
+// Compiler version assertions
+#if defined(__INTEL_COMPILER)
+#  if __INTEL_COMPILER < 1800
+#    error pybind11 requires Intel C++ compiler v18 or newer
+#  endif
+#elif defined(__clang__) && !defined(__apple_build_version__)
+#  if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 3)
+#    error pybind11 requires clang 3.3 or newer
+#  endif
+#elif defined(__clang__)
+// Apple changes clang version macros to its Xcode version; the first Xcode release based on
+// (upstream) clang 3.3 was Xcode 5:
+#  if __clang_major__ < 5
+#    error pybind11 requires Xcode/clang 5.0 or newer
+#  endif
+#elif defined(__GNUG__)
+#  if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
+#    error pybind11 requires gcc 4.8 or newer
+#  endif
+#elif defined(_MSC_VER)
+// Pybind hits various compiler bugs in 2015u2 and earlier, and also makes use of some stl features
+// (e.g. std::negation) added in 2015u3:
+#  if _MSC_FULL_VER < 190024210
+#    error pybind11 requires MSVC 2015 update 3 or newer
+#  endif
+#endif
+
+#if !defined(PYBIND11_EXPORT)
+#  if defined(WIN32) || defined(_WIN32)
+#    define PYBIND11_EXPORT __declspec(dllexport)
+#  else
+#    define PYBIND11_EXPORT __attribute__ ((visibility("default")))
+#  endif
+#endif
+
+#if defined(_MSC_VER)
+#  define PYBIND11_NOINLINE __declspec(noinline)
+#else
+#  define PYBIND11_NOINLINE __attribute__ ((noinline))
+#endif
+
+#if defined(PYBIND11_CPP14)
+#  define PYBIND11_DEPRECATED(reason) [[deprecated(reason)]]
+#else
+#  define PYBIND11_DEPRECATED(reason) __attribute__((deprecated(reason)))
+#endif
+
+#if defined(PYBIND11_CPP17)
+#  define PYBIND11_MAYBE_UNUSED [[maybe_unused]]
+#elif defined(_MSC_VER) && !defined(__clang__)
+#  define PYBIND11_MAYBE_UNUSED
+#else
+#  define PYBIND11_MAYBE_UNUSED __attribute__ ((__unused__))
+#endif
+
+/* Don't let Python.h #define (v)snprintf as macro because they are implemented
+   properly in Visual Studio since 2015. */
+#if defined(_MSC_VER) && _MSC_VER >= 1900
+#  define HAVE_SNPRINTF 1
+#endif
+
+/// Include Python header, disable linking to pythonX_d.lib on Windows in debug mode
+#if defined(_MSC_VER)
+#  if (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 4)
+#    define HAVE_ROUND 1
+#  endif
+#  pragma warning(push)
+#  pragma warning(disable: 4510 4610 4512 4005)
+#  if defined(_DEBUG) && !defined(Py_DEBUG)
+#    define PYBIND11_DEBUG_MARKER
+#    undef _DEBUG
+#  endif
+#endif
+
+#include <Python.h>
+#include <frameobject.h>
+#include <pythread.h>
+
+/* Python #defines overrides on all sorts of core functions, which
+   tends to weak havok in C++ codebases that expect these to work
+   like regular functions (potentially with several overloads) */
+#if defined(isalnum)
+#  undef isalnum
+#  undef isalpha
+#  undef islower
+#  undef isspace
+#  undef isupper
+#  undef tolower
+#  undef toupper
+#endif
+
+#if defined(copysign)
+#  undef copysign
+#endif
+
+#if defined(_MSC_VER)
+#  if defined(PYBIND11_DEBUG_MARKER)
+#    define _DEBUG
+#    undef PYBIND11_DEBUG_MARKER
+#  endif
+#  pragma warning(pop)
+#endif
+
+#include <cstddef>
+#include <cstring>
+#include <forward_list>
+#include <vector>
+#include <string>
+#include <stdexcept>
+#include <exception>
+#include <unordered_set>
+#include <unordered_map>
+#include <memory>
+#include <typeindex>
+#include <type_traits>
+
+#if PY_MAJOR_VERSION >= 3 /// Compatibility macros for various Python versions
+#define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyInstanceMethod_New(ptr)
+#define PYBIND11_INSTANCE_METHOD_CHECK PyInstanceMethod_Check
+#define PYBIND11_INSTANCE_METHOD_GET_FUNCTION PyInstanceMethod_GET_FUNCTION
+#define PYBIND11_BYTES_CHECK PyBytes_Check
+#define PYBIND11_BYTES_FROM_STRING PyBytes_FromString
+#define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyBytes_FromStringAndSize
+#define PYBIND11_BYTES_AS_STRING_AND_SIZE PyBytes_AsStringAndSize
+#define PYBIND11_BYTES_AS_STRING PyBytes_AsString
+#define PYBIND11_BYTES_SIZE PyBytes_Size
+#define PYBIND11_LONG_CHECK(o) PyLong_Check(o)
+#define PYBIND11_LONG_AS_LONGLONG(o) PyLong_AsLongLong(o)
+#define PYBIND11_LONG_FROM_SIGNED(o) PyLong_FromSsize_t((ssize_t) o)
+#define PYBIND11_LONG_FROM_UNSIGNED(o) PyLong_FromSize_t((size_t) o)
+#define PYBIND11_BYTES_NAME "bytes"
+#define PYBIND11_STRING_NAME "str"
+#define PYBIND11_SLICE_OBJECT PyObject
+#define PYBIND11_FROM_STRING PyUnicode_FromString
+#define PYBIND11_STR_TYPE ::pybind11::str
+#define PYBIND11_BOOL_ATTR "__bool__"
+#define PYBIND11_NB_BOOL(ptr) ((ptr)->nb_bool)
+#define PYBIND11_BUILTINS_MODULE "builtins"
+// Providing a separate declaration to make Clang's -Wmissing-prototypes happy.
+// See comment for PYBIND11_MODULE below for why this is marked "maybe unused".
+#define PYBIND11_PLUGIN_IMPL(name) \
+    extern "C" PYBIND11_MAYBE_UNUSED PYBIND11_EXPORT PyObject *PyInit_##name(); \
+    extern "C" PYBIND11_EXPORT PyObject *PyInit_##name()
+
+#else
+#define PYBIND11_INSTANCE_METHOD_NEW(ptr, class_) PyMethod_New(ptr, nullptr, class_)
+#define PYBIND11_INSTANCE_METHOD_CHECK PyMethod_Check
+#define PYBIND11_INSTANCE_METHOD_GET_FUNCTION PyMethod_GET_FUNCTION
+#define PYBIND11_BYTES_CHECK PyString_Check
+#define PYBIND11_BYTES_FROM_STRING PyString_FromString
+#define PYBIND11_BYTES_FROM_STRING_AND_SIZE PyString_FromStringAndSize
+#define PYBIND11_BYTES_AS_STRING_AND_SIZE PyString_AsStringAndSize
+#define PYBIND11_BYTES_AS_STRING PyString_AsString
+#define PYBIND11_BYTES_SIZE PyString_Size
+#define PYBIND11_LONG_CHECK(o) (PyInt_Check(o) || PyLong_Check(o))
+#define PYBIND11_LONG_AS_LONGLONG(o) (PyInt_Check(o) ? (long long) PyLong_AsLong(o) : PyLong_AsLongLong(o))
+#define PYBIND11_LONG_FROM_SIGNED(o) PyInt_FromSsize_t((ssize_t) o) // Returns long if needed.
+#define PYBIND11_LONG_FROM_UNSIGNED(o) PyInt_FromSize_t((size_t) o) // Returns long if needed.
+#define PYBIND11_BYTES_NAME "str"
+#define PYBIND11_STRING_NAME "unicode"
+#define PYBIND11_SLICE_OBJECT PySliceObject
+#define PYBIND11_FROM_STRING PyString_FromString
+#define PYBIND11_STR_TYPE ::pybind11::bytes
+#define PYBIND11_BOOL_ATTR "__nonzero__"
+#define PYBIND11_NB_BOOL(ptr) ((ptr)->nb_nonzero)
+#define PYBIND11_BUILTINS_MODULE "__builtin__"
+// Providing a separate PyInit decl to make Clang's -Wmissing-prototypes happy.
+// See comment for PYBIND11_MODULE below for why this is marked "maybe unused".
+#define PYBIND11_PLUGIN_IMPL(name) \
+    static PyObject *pybind11_init_wrapper();                           \
+    extern "C" PYBIND11_MAYBE_UNUSED PYBIND11_EXPORT void init##name(); \
+    extern "C" PYBIND11_EXPORT void init##name() {                      \
+        (void)pybind11_init_wrapper();                                  \
+    }                                                                   \
+    PyObject *pybind11_init_wrapper()
+#endif
+
+#if PY_VERSION_HEX >= 0x03050000 && PY_VERSION_HEX < 0x03050200
+extern "C" {
+    struct _Py_atomic_address { void *value; };
+    PyAPI_DATA(_Py_atomic_address) _PyThreadState_Current;
+}
+#endif
+
+#define PYBIND11_TRY_NEXT_OVERLOAD ((PyObject *) 1) // special failure return code
+#define PYBIND11_STRINGIFY(x) #x
+#define PYBIND11_TOSTRING(x) PYBIND11_STRINGIFY(x)
+#define PYBIND11_CONCAT(first, second) first##second
+#define PYBIND11_ENSURE_INTERNALS_READY \
+    pybind11::detail::get_internals();
+
+#define PYBIND11_CHECK_PYTHON_VERSION \
+    {                                                                          \
+        const char *compiled_ver = PYBIND11_TOSTRING(PY_MAJOR_VERSION)         \
+            "." PYBIND11_TOSTRING(PY_MINOR_VERSION);                           \
+        const char *runtime_ver = Py_GetVersion();                             \
+        size_t len = std::strlen(compiled_ver);                                \
+        if (std::strncmp(runtime_ver, compiled_ver, len) != 0                  \
+                || (runtime_ver[len] >= '0' && runtime_ver[len] <= '9')) {     \
+            PyErr_Format(PyExc_ImportError,                                    \
+                "Python version mismatch: module was compiled for Python %s, " \
+                "but the interpreter version is incompatible: %s.",            \
+                compiled_ver, runtime_ver);                                    \
+            return nullptr;                                                    \
+        }                                                                      \
+    }
+
+#define PYBIND11_CATCH_INIT_EXCEPTIONS \
+        catch (pybind11::error_already_set &e) {                               \
+            PyErr_SetString(PyExc_ImportError, e.what());                      \
+            return nullptr;                                                    \
+        } catch (const std::exception &e) {                                    \
+            PyErr_SetString(PyExc_ImportError, e.what());                      \
+            return nullptr;                                                    \
+        }                                                                      \
+
+/** \rst
+    ***Deprecated in favor of PYBIND11_MODULE***
+
+    This macro creates the entry point that will be invoked when the Python interpreter
+    imports a plugin library. Please create a `module_` in the function body and return
+    the pointer to its underlying Python object at the end.
+
+    .. code-block:: cpp
+
+        PYBIND11_PLUGIN(example) {
+            pybind11::module_ m("example", "pybind11 example plugin");
+            /// Set up bindings here
+            return m.ptr();
+        }
+\endrst */
+#define PYBIND11_PLUGIN(name)                                                  \
+    PYBIND11_DEPRECATED("PYBIND11_PLUGIN is deprecated, use PYBIND11_MODULE")  \
+    static PyObject *pybind11_init();                                          \
+    PYBIND11_PLUGIN_IMPL(name) {                                               \
+        PYBIND11_CHECK_PYTHON_VERSION                                          \
+        PYBIND11_ENSURE_INTERNALS_READY                                        \
+        try {                                                                  \
+            return pybind11_init();                                            \
+        } PYBIND11_CATCH_INIT_EXCEPTIONS                                       \
+    }                                                                          \
+    PyObject *pybind11_init()
+
+/** \rst
+    This macro creates the entry point that will be invoked when the Python interpreter
+    imports an extension module. The module name is given as the fist argument and it
+    should not be in quotes. The second macro argument defines a variable of type
+    `py::module_` which can be used to initialize the module.
+
+    The entry point is marked as "maybe unused" to aid dead-code detection analysis:
+    since the entry point is typically only looked up at runtime and not referenced
+    during translation, it would otherwise appear as unused ("dead") code.
+
+    .. code-block:: cpp
+
+        PYBIND11_MODULE(example, m) {
+            m.doc() = "pybind11 example module";
+
+            // Add bindings here
+            m.def("foo", []() {
+                return "Hello, World!";
+            });
+        }
+\endrst */
+#define PYBIND11_MODULE(name, variable)                                        \
+    static ::pybind11::module_::module_def                                     \
+        PYBIND11_CONCAT(pybind11_module_def_, name) PYBIND11_MAYBE_UNUSED;     \
+    PYBIND11_MAYBE_UNUSED                                                      \
+    static void PYBIND11_CONCAT(pybind11_init_, name)(::pybind11::module_ &);  \
+    PYBIND11_PLUGIN_IMPL(name) {                                               \
+        PYBIND11_CHECK_PYTHON_VERSION                                          \
+        PYBIND11_ENSURE_INTERNALS_READY                                        \
+        auto m = ::pybind11::module_::create_extension_module(                 \
+            PYBIND11_TOSTRING(name), nullptr,                                  \
+            &PYBIND11_CONCAT(pybind11_module_def_, name));                     \
+        try {                                                                  \
+            PYBIND11_CONCAT(pybind11_init_, name)(m);                          \
+            return m.ptr();                                                    \
+        } PYBIND11_CATCH_INIT_EXCEPTIONS                                       \
+    }                                                                          \
+    void PYBIND11_CONCAT(pybind11_init_, name)(::pybind11::module_ &variable)
+
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+
+using ssize_t = Py_ssize_t;
+using size_t  = std::size_t;
+
+/// Approach used to cast a previously unknown C++ instance into a Python object
+enum class return_value_policy : uint8_t {
+    /** This is the default return value policy, which falls back to the policy
+        return_value_policy::take_ownership when the return value is a pointer.
+        Otherwise, it uses return_value::move or return_value::copy for rvalue
+        and lvalue references, respectively. See below for a description of what
+        all of these different policies do. */
+    automatic = 0,
+
+    /** As above, but use policy return_value_policy::reference when the return
+        value is a pointer. This is the default conversion policy for function
+        arguments when calling Python functions manually from C++ code (i.e. via
+        handle::operator()). You probably won't need to use this. */
+    automatic_reference,
+
+    /** Reference an existing object (i.e. do not create a new copy) and take
+        ownership. Python will call the destructor and delete operator when the
+        object’s reference count reaches zero. Undefined behavior ensues when
+        the C++ side does the same.. */
+    take_ownership,
+
+    /** Create a new copy of the returned object, which will be owned by
+        Python. This policy is comparably safe because the lifetimes of the two
+        instances are decoupled. */
+    copy,
+
+    /** Use std::move to move the return value contents into a new instance
+        that will be owned by Python. This policy is comparably safe because the
+        lifetimes of the two instances (move source and destination) are
+        decoupled. */
+    move,
+
+    /** Reference an existing object, but do not take ownership. The C++ side
+        is responsible for managing the object’s lifetime and deallocating it
+        when it is no longer used. Warning: undefined behavior will ensue when
+        the C++ side deletes an object that is still referenced and used by
+        Python. */
+    reference,
+
+    /** This policy only applies to methods and properties. It references the
+        object without taking ownership similar to the above
+        return_value_policy::reference policy. In contrast to that policy, the
+        function or property’s implicit this argument (called the parent) is
+        considered to be the the owner of the return value (the child).
+        pybind11 then couples the lifetime of the parent to the child via a
+        reference relationship that ensures that the parent cannot be garbage
+        collected while Python is still using the child. More advanced
+        variations of this scheme are also possible using combinations of
+        return_value_policy::reference and the keep_alive call policy */
+    reference_internal
+};
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+inline static constexpr int log2(size_t n, int k = 0) { return (n <= 1) ? k : log2(n >> 1, k + 1); }
+
+// Returns the size as a multiple of sizeof(void *), rounded up.
+inline static constexpr size_t size_in_ptrs(size_t s) { return 1 + ((s - 1) >> log2(sizeof(void *))); }
+
+/**
+ * The space to allocate for simple layout instance holders (see below) in multiple of the size of
+ * a pointer (e.g.  2 means 16 bytes on 64-bit architectures).  The default is the minimum required
+ * to holder either a std::unique_ptr or std::shared_ptr (which is almost always
+ * sizeof(std::shared_ptr<T>)).
+ */
+constexpr size_t instance_simple_holder_in_ptrs() {
+    static_assert(sizeof(std::shared_ptr<int>) >= sizeof(std::unique_ptr<int>),
+            "pybind assumes std::shared_ptrs are at least as big as std::unique_ptrs");
+    return size_in_ptrs(sizeof(std::shared_ptr<int>));
+}
+
+// Forward declarations
+struct type_info;
+struct value_and_holder;
+
+struct nonsimple_values_and_holders {
+    void **values_and_holders;
+    uint8_t *status;
+};
+
+/// The 'instance' type which needs to be standard layout (need to be able to use 'offsetof')
+struct instance {
+    PyObject_HEAD
+    /// Storage for pointers and holder; see simple_layout, below, for a description
+    union {
+        void *simple_value_holder[1 + instance_simple_holder_in_ptrs()];
+        nonsimple_values_and_holders nonsimple;
+    };
+    /// Weak references
+    PyObject *weakrefs;
+    /// If true, the pointer is owned which means we're free to manage it with a holder.
+    bool owned : 1;
+    /**
+     * An instance has two possible value/holder layouts.
+     *
+     * Simple layout (when this flag is true), means the `simple_value_holder` is set with a pointer
+     * and the holder object governing that pointer, i.e. [val1*][holder].  This layout is applied
+     * whenever there is no python-side multiple inheritance of bound C++ types *and* the type's
+     * holder will fit in the default space (which is large enough to hold either a std::unique_ptr
+     * or std::shared_ptr).
+     *
+     * Non-simple layout applies when using custom holders that require more space than `shared_ptr`
+     * (which is typically the size of two pointers), or when multiple inheritance is used on the
+     * python side.  Non-simple layout allocates the required amount of memory to have multiple
+     * bound C++ classes as parents.  Under this layout, `nonsimple.values_and_holders` is set to a
+     * pointer to allocated space of the required space to hold a sequence of value pointers and
+     * holders followed `status`, a set of bit flags (1 byte each), i.e.
+     * [val1*][holder1][val2*][holder2]...[bb...]  where each [block] is rounded up to a multiple of
+     * `sizeof(void *)`.  `nonsimple.status` is, for convenience, a pointer to the
+     * beginning of the [bb...] block (but not independently allocated).
+     *
+     * Status bits indicate whether the associated holder is constructed (&
+     * status_holder_constructed) and whether the value pointer is registered (&
+     * status_instance_registered) in `registered_instances`.
+     */
+    bool simple_layout : 1;
+    /// For simple layout, tracks whether the holder has been constructed
+    bool simple_holder_constructed : 1;
+    /// For simple layout, tracks whether the instance is registered in `registered_instances`
+    bool simple_instance_registered : 1;
+    /// If true, get_internals().patients has an entry for this object
+    bool has_patients : 1;
+
+    /// Initializes all of the above type/values/holders data (but not the instance values themselves)
+    void allocate_layout();
+
+    /// Destroys/deallocates all of the above
+    void deallocate_layout();
+
+    /// Returns the value_and_holder wrapper for the given type (or the first, if `find_type`
+    /// omitted).  Returns a default-constructed (with `.inst = nullptr`) object on failure if
+    /// `throw_if_missing` is false.
+    value_and_holder get_value_and_holder(const type_info *find_type = nullptr, bool throw_if_missing = true);
+
+    /// Bit values for the non-simple status flags
+    static constexpr uint8_t status_holder_constructed  = 1;
+    static constexpr uint8_t status_instance_registered = 2;
+};
+
+static_assert(std::is_standard_layout<instance>::value, "Internal error: `pybind11::detail::instance` is not standard layout!");
+
+/// from __cpp_future__ import (convenient aliases from C++14/17)
+#if defined(PYBIND11_CPP14) && (!defined(_MSC_VER) || _MSC_VER >= 1910)
+using std::enable_if_t;
+using std::conditional_t;
+using std::remove_cv_t;
+using std::remove_reference_t;
+#else
+template <bool B, typename T = void> using enable_if_t = typename std::enable_if<B, T>::type;
+template <bool B, typename T, typename F> using conditional_t = typename std::conditional<B, T, F>::type;
+template <typename T> using remove_cv_t = typename std::remove_cv<T>::type;
+template <typename T> using remove_reference_t = typename std::remove_reference<T>::type;
+#endif
+
+/// Index sequences
+#if defined(PYBIND11_CPP14)
+using std::index_sequence;
+using std::make_index_sequence;
+#else
+template<size_t ...> struct index_sequence  { };
+template<size_t N, size_t ...S> struct make_index_sequence_impl : make_index_sequence_impl <N - 1, N - 1, S...> { };
+template<size_t ...S> struct make_index_sequence_impl <0, S...> { using type = index_sequence<S...>; };
+template<size_t N> using make_index_sequence = typename make_index_sequence_impl<N>::type;
+#endif
+
+/// Make an index sequence of the indices of true arguments
+template <typename ISeq, size_t, bool...> struct select_indices_impl { using type = ISeq; };
+template <size_t... IPrev, size_t I, bool B, bool... Bs> struct select_indices_impl<index_sequence<IPrev...>, I, B, Bs...>
+    : select_indices_impl<conditional_t<B, index_sequence<IPrev..., I>, index_sequence<IPrev...>>, I + 1, Bs...> {};
+template <bool... Bs> using select_indices = typename select_indices_impl<index_sequence<>, 0, Bs...>::type;
+
+/// Backports of std::bool_constant and std::negation to accommodate older compilers
+template <bool B> using bool_constant = std::integral_constant<bool, B>;
+template <typename T> struct negation : bool_constant<!T::value> { };
+
+// PGI/Intel cannot detect operator delete with the "compatible" void_t impl, so
+// using the new one (C++14 defect, so generally works on newer compilers, even
+// if not in C++17 mode)
+#if defined(__PGIC__) || defined(__INTEL_COMPILER)
+template<typename... > using void_t = void;
+#else
+template <typename...> struct void_t_impl { using type = void; };
+template <typename... Ts> using void_t = typename void_t_impl<Ts...>::type;
+#endif
+
+
+/// Compile-time all/any/none of that check the boolean value of all template types
+#if defined(__cpp_fold_expressions) && !(defined(_MSC_VER) && (_MSC_VER < 1916))
+template <class... Ts> using all_of = bool_constant<(Ts::value && ...)>;
+template <class... Ts> using any_of = bool_constant<(Ts::value || ...)>;
+#elif !defined(_MSC_VER)
+template <bool...> struct bools {};
+template <class... Ts> using all_of = std::is_same<
+    bools<Ts::value..., true>,
+    bools<true, Ts::value...>>;
+template <class... Ts> using any_of = negation<all_of<negation<Ts>...>>;
+#else
+// MSVC has trouble with the above, but supports std::conjunction, which we can use instead (albeit
+// at a slight loss of compilation efficiency).
+template <class... Ts> using all_of = std::conjunction<Ts...>;
+template <class... Ts> using any_of = std::disjunction<Ts...>;
+#endif
+template <class... Ts> using none_of = negation<any_of<Ts...>>;
+
+template <class T, template<class> class... Predicates> using satisfies_all_of = all_of<Predicates<T>...>;
+template <class T, template<class> class... Predicates> using satisfies_any_of = any_of<Predicates<T>...>;
+template <class T, template<class> class... Predicates> using satisfies_none_of = none_of<Predicates<T>...>;
+
+/// Strip the class from a method type
+template <typename T> struct remove_class { };
+template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...)> { using type = R (A...); };
+template <typename C, typename R, typename... A> struct remove_class<R (C::*)(A...) const> { using type = R (A...); };
+
+/// Helper template to strip away type modifiers
+template <typename T> struct intrinsic_type                       { using type = T; };
+template <typename T> struct intrinsic_type<const T>              { using type = typename intrinsic_type<T>::type; };
+template <typename T> struct intrinsic_type<T*>                   { using type = typename intrinsic_type<T>::type; };
+template <typename T> struct intrinsic_type<T&>                   { using type = typename intrinsic_type<T>::type; };
+template <typename T> struct intrinsic_type<T&&>                  { using type = typename intrinsic_type<T>::type; };
+template <typename T, size_t N> struct intrinsic_type<const T[N]> { using type = typename intrinsic_type<T>::type; };
+template <typename T, size_t N> struct intrinsic_type<T[N]>       { using type = typename intrinsic_type<T>::type; };
+template <typename T> using intrinsic_t = typename intrinsic_type<T>::type;
+
+/// Helper type to replace 'void' in some expressions
+struct void_type { };
+
+/// Helper template which holds a list of types
+template <typename...> struct type_list { };
+
+/// Compile-time integer sum
+#ifdef __cpp_fold_expressions
+template <typename... Ts> constexpr size_t constexpr_sum(Ts... ns) { return (0 + ... + size_t{ns}); }
+#else
+constexpr size_t constexpr_sum() { return 0; }
+template <typename T, typename... Ts>
+constexpr size_t constexpr_sum(T n, Ts... ns) { return size_t{n} + constexpr_sum(ns...); }
+#endif
+
+PYBIND11_NAMESPACE_BEGIN(constexpr_impl)
+/// Implementation details for constexpr functions
+constexpr int first(int i) { return i; }
+template <typename T, typename... Ts>
+constexpr int first(int i, T v, Ts... vs) { return v ? i : first(i + 1, vs...); }
+
+constexpr int last(int /*i*/, int result) { return result; }
+template <typename T, typename... Ts>
+constexpr int last(int i, int result, T v, Ts... vs) { return last(i + 1, v ? i : result, vs...); }
+PYBIND11_NAMESPACE_END(constexpr_impl)
+
+/// Return the index of the first type in Ts which satisfies Predicate<T>.  Returns sizeof...(Ts) if
+/// none match.
+template <template<typename> class Predicate, typename... Ts>
+constexpr int constexpr_first() { return constexpr_impl::first(0, Predicate<Ts>::value...); }
+
+/// Return the index of the last type in Ts which satisfies Predicate<T>, or -1 if none match.
+template <template<typename> class Predicate, typename... Ts>
+constexpr int constexpr_last() { return constexpr_impl::last(0, -1, Predicate<Ts>::value...); }
+
+/// Return the Nth element from the parameter pack
+template <size_t N, typename T, typename... Ts>
+struct pack_element { using type = typename pack_element<N - 1, Ts...>::type; };
+template <typename T, typename... Ts>
+struct pack_element<0, T, Ts...> { using type = T; };
+
+/// Return the one and only type which matches the predicate, or Default if none match.
+/// If more than one type matches the predicate, fail at compile-time.
+template <template<typename> class Predicate, typename Default, typename... Ts>
+struct exactly_one {
+    static constexpr auto found = constexpr_sum(Predicate<Ts>::value...);
+    static_assert(found <= 1, "Found more than one type matching the predicate");
+
+    static constexpr auto index = found ? constexpr_first<Predicate, Ts...>() : 0;
+    using type = conditional_t<found, typename pack_element<index, Ts...>::type, Default>;
+};
+template <template<typename> class P, typename Default>
+struct exactly_one<P, Default> { using type = Default; };
+
+template <template<typename> class Predicate, typename Default, typename... Ts>
+using exactly_one_t = typename exactly_one<Predicate, Default, Ts...>::type;
+
+/// Defer the evaluation of type T until types Us are instantiated
+template <typename T, typename... /*Us*/> struct deferred_type { using type = T; };
+template <typename T, typename... Us> using deferred_t = typename deferred_type<T, Us...>::type;
+
+/// Like is_base_of, but requires a strict base (i.e. `is_strict_base_of<T, T>::value == false`,
+/// unlike `std::is_base_of`)
+template <typename Base, typename Derived> using is_strict_base_of = bool_constant<
+    std::is_base_of<Base, Derived>::value && !std::is_same<Base, Derived>::value>;
+
+/// Like is_base_of, but also requires that the base type is accessible (i.e. that a Derived pointer
+/// can be converted to a Base pointer)
+/// For unions, `is_base_of<T, T>::value` is False, so we need to check `is_same` as well.
+template <typename Base, typename Derived> using is_accessible_base_of = bool_constant<
+    (std::is_same<Base, Derived>::value || std::is_base_of<Base, Derived>::value) && std::is_convertible<Derived *, Base *>::value>;
+
+template <template<typename...> class Base>
+struct is_template_base_of_impl {
+    template <typename... Us> static std::true_type check(Base<Us...> *);
+    static std::false_type check(...);
+};
+
+/// Check if a template is the base of a type. For example:
+/// `is_template_base_of<Base, T>` is true if `struct T : Base<U> {}` where U can be anything
+template <template<typename...> class Base, typename T>
+#if !defined(_MSC_VER)
+using is_template_base_of = decltype(is_template_base_of_impl<Base>::check((intrinsic_t<T>*)nullptr));
+#else // MSVC2015 has trouble with decltype in template aliases
+struct is_template_base_of : decltype(is_template_base_of_impl<Base>::check((intrinsic_t<T>*)nullptr)) { };
+#endif
+
+/// Check if T is an instantiation of the template `Class`. For example:
+/// `is_instantiation<shared_ptr, T>` is true if `T == shared_ptr<U>` where U can be anything.
+template <template<typename...> class Class, typename T>
+struct is_instantiation : std::false_type { };
+template <template<typename...> class Class, typename... Us>
+struct is_instantiation<Class, Class<Us...>> : std::true_type { };
+
+/// Check if T is std::shared_ptr<U> where U can be anything
+template <typename T> using is_shared_ptr = is_instantiation<std::shared_ptr, T>;
+
+/// Check if T looks like an input iterator
+template <typename T, typename = void> struct is_input_iterator : std::false_type {};
+template <typename T>
+struct is_input_iterator<T, void_t<decltype(*std::declval<T &>()), decltype(++std::declval<T &>())>>
+    : std::true_type {};
+
+template <typename T> using is_function_pointer = bool_constant<
+    std::is_pointer<T>::value && std::is_function<typename std::remove_pointer<T>::type>::value>;
+
+template <typename F> struct strip_function_object {
+    using type = typename remove_class<decltype(&F::operator())>::type;
+};
+
+// Extracts the function signature from a function, function pointer or lambda.
+template <typename Function, typename F = remove_reference_t<Function>>
+using function_signature_t = conditional_t<
+    std::is_function<F>::value,
+    F,
+    typename conditional_t<
+        std::is_pointer<F>::value || std::is_member_pointer<F>::value,
+        std::remove_pointer<F>,
+        strip_function_object<F>
+    >::type
+>;
+
+/// Returns true if the type looks like a lambda: that is, isn't a function, pointer or member
+/// pointer.  Note that this can catch all sorts of other things, too; this is intended to be used
+/// in a place where passing a lambda makes sense.
+template <typename T> using is_lambda = satisfies_none_of<remove_reference_t<T>,
+        std::is_function, std::is_pointer, std::is_member_pointer>;
+
+/// Ignore that a variable is unused in compiler warnings
+inline void ignore_unused(const int *) { }
+
+/// Apply a function over each element of a parameter pack
+#ifdef __cpp_fold_expressions
+#define PYBIND11_EXPAND_SIDE_EFFECTS(PATTERN) (((PATTERN), void()), ...)
+#else
+using expand_side_effects = bool[];
+#define PYBIND11_EXPAND_SIDE_EFFECTS(PATTERN) (void)pybind11::detail::expand_side_effects{ ((PATTERN), void(), false)..., false }
+#endif
+
+PYBIND11_NAMESPACE_END(detail)
+
+/// C++ bindings of builtin Python exceptions
+class builtin_exception : public std::runtime_error {
+public:
+    using std::runtime_error::runtime_error;
+    /// Set the error using the Python C API
+    virtual void set_error() const = 0;
+};
+
+#define PYBIND11_RUNTIME_EXCEPTION(name, type) \
+    class name : public builtin_exception { public: \
+        using builtin_exception::builtin_exception; \
+        name() : name("") { } \
+        void set_error() const override { PyErr_SetString(type, what()); } \
+    };
+
+PYBIND11_RUNTIME_EXCEPTION(stop_iteration, PyExc_StopIteration)
+PYBIND11_RUNTIME_EXCEPTION(index_error, PyExc_IndexError)
+PYBIND11_RUNTIME_EXCEPTION(key_error, PyExc_KeyError)
+PYBIND11_RUNTIME_EXCEPTION(value_error, PyExc_ValueError)
+PYBIND11_RUNTIME_EXCEPTION(type_error, PyExc_TypeError)
+PYBIND11_RUNTIME_EXCEPTION(buffer_error, PyExc_BufferError)
+PYBIND11_RUNTIME_EXCEPTION(import_error, PyExc_ImportError)
+PYBIND11_RUNTIME_EXCEPTION(cast_error, PyExc_RuntimeError) /// Thrown when pybind11::cast or handle::call fail due to a type casting error
+PYBIND11_RUNTIME_EXCEPTION(reference_cast_error, PyExc_RuntimeError) /// Used internally
+
+[[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const char *reason) { throw std::runtime_error(reason); }
+[[noreturn]] PYBIND11_NOINLINE inline void pybind11_fail(const std::string &reason) { throw std::runtime_error(reason); }
+
+template <typename T, typename SFINAE = void> struct format_descriptor { };
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+// Returns the index of the given type in the type char array below, and in the list in numpy.h
+// The order here is: bool; 8 ints ((signed,unsigned)x(8,16,32,64)bits); float,double,long double;
+// complex float,double,long double.  Note that the long double types only participate when long
+// double is actually longer than double (it isn't under MSVC).
+// NB: not only the string below but also complex.h and numpy.h rely on this order.
+template <typename T, typename SFINAE = void> struct is_fmt_numeric { static constexpr bool value = false; };
+template <typename T> struct is_fmt_numeric<T, enable_if_t<std::is_arithmetic<T>::value>> {
+    static constexpr bool value = true;
+    static constexpr int index = std::is_same<T, bool>::value ? 0 : 1 + (
+        std::is_integral<T>::value ? detail::log2(sizeof(T))*2 + std::is_unsigned<T>::value : 8 + (
+        std::is_same<T, double>::value ? 1 : std::is_same<T, long double>::value ? 2 : 0));
+};
+PYBIND11_NAMESPACE_END(detail)
+
+template <typename T> struct format_descriptor<T, detail::enable_if_t<std::is_arithmetic<T>::value>> {
+    static constexpr const char c = "?bBhHiIqQfdg"[detail::is_fmt_numeric<T>::index];
+    static constexpr const char value[2] = { c, '\0' };
+    static std::string format() { return std::string(1, c); }
+};
+
+#if !defined(PYBIND11_CPP17)
+
+template <typename T> constexpr const char format_descriptor<
+    T, detail::enable_if_t<std::is_arithmetic<T>::value>>::value[2];
+
+#endif
+
+/// RAII wrapper that temporarily clears any Python error state
+struct error_scope {
+    PyObject *type, *value, *trace;
+    error_scope() { PyErr_Fetch(&type, &value, &trace); }
+    ~error_scope() { PyErr_Restore(type, value, trace); }
+};
+
+/// Dummy destructor wrapper that can be used to expose classes with a private destructor
+struct nodelete { template <typename T> void operator()(T*) { } };
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+template <typename... Args>
+struct overload_cast_impl {
+    constexpr overload_cast_impl() {}; // NOLINT(modernize-use-equals-default):  MSVC 2015 needs this
+
+    template <typename Return>
+    constexpr auto operator()(Return (*pf)(Args...)) const noexcept
+                              -> decltype(pf) { return pf; }
+
+    template <typename Return, typename Class>
+    constexpr auto operator()(Return (Class::*pmf)(Args...), std::false_type = {}) const noexcept
+                              -> decltype(pmf) { return pmf; }
+
+    template <typename Return, typename Class>
+    constexpr auto operator()(Return (Class::*pmf)(Args...) const, std::true_type) const noexcept
+                              -> decltype(pmf) { return pmf; }
+};
+PYBIND11_NAMESPACE_END(detail)
+
+// overload_cast requires variable templates: C++14
+#if defined(PYBIND11_CPP14)
+#define PYBIND11_OVERLOAD_CAST 1
+/// Syntax sugar for resolving overloaded function pointers:
+///  - regular: static_cast<Return (Class::*)(Arg0, Arg1, Arg2)>(&Class::func)
+///  - sweet:   overload_cast<Arg0, Arg1, Arg2>(&Class::func)
+template <typename... Args>
+static constexpr detail::overload_cast_impl<Args...> overload_cast = {};
+// MSVC 2015 only accepts this particular initialization syntax for this variable template.
+#endif
+
+/// Const member function selector for overload_cast
+///  - regular: static_cast<Return (Class::*)(Arg) const>(&Class::func)
+///  - sweet:   overload_cast<Arg>(&Class::func, const_)
+static constexpr auto const_ = std::true_type{};
+
+#if !defined(PYBIND11_CPP14) // no overload_cast: providing something that static_assert-fails:
+template <typename... Args> struct overload_cast {
+    static_assert(detail::deferred_t<std::false_type, Args...>::value,
+                  "pybind11::overload_cast<...> requires compiling in C++14 mode");
+};
+#endif // overload_cast
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+// Adaptor for converting arbitrary container arguments into a vector; implicitly convertible from
+// any standard container (or C-style array) supporting std::begin/std::end, any singleton
+// arithmetic type (if T is arithmetic), or explicitly constructible from an iterator pair.
+template <typename T>
+class any_container {
+    std::vector<T> v;
+public:
+    any_container() = default;
+
+    // Can construct from a pair of iterators
+    template <typename It, typename = enable_if_t<is_input_iterator<It>::value>>
+    any_container(It first, It last) : v(first, last) { }
+
+    // Implicit conversion constructor from any arbitrary container type with values convertible to T
+    template <typename Container, typename = enable_if_t<std::is_convertible<decltype(*std::begin(std::declval<const Container &>())), T>::value>>
+    any_container(const Container &c) : any_container(std::begin(c), std::end(c)) { }
+
+    // initializer_list's aren't deducible, so don't get matched by the above template; we need this
+    // to explicitly allow implicit conversion from one:
+    template <typename TIn, typename = enable_if_t<std::is_convertible<TIn, T>::value>>
+    any_container(const std::initializer_list<TIn> &c) : any_container(c.begin(), c.end()) { }
+
+    // Avoid copying if given an rvalue vector of the correct type.
+    any_container(std::vector<T> &&v) : v(std::move(v)) { }
+
+    // Moves the vector out of an rvalue any_container
+    operator std::vector<T> &&() && { return std::move(v); }
+
+    // Dereferencing obtains a reference to the underlying vector
+    std::vector<T> &operator*() { return v; }
+    const std::vector<T> &operator*() const { return v; }
+
+    // -> lets you call methods on the underlying vector
+    std::vector<T> *operator->() { return &v; }
+    const std::vector<T> *operator->() const { return &v; }
+};
+
+// Forward-declaration; see detail/class.h
+std::string get_fully_qualified_tp_name(PyTypeObject*);
+
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/detail/descr.h b/libs/pybind/pybind11/detail/descr.h
new file mode 100644
index 0000000000..92720cd562
--- /dev/null
+++ b/libs/pybind/pybind11/detail/descr.h
@@ -0,0 +1,100 @@
+/*
+    pybind11/detail/descr.h: Helper type for concatenating type signatures at compile time
+
+    Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "common.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+#if !defined(_MSC_VER)
+#  define PYBIND11_DESCR_CONSTEXPR static constexpr
+#else
+#  define PYBIND11_DESCR_CONSTEXPR const
+#endif
+
+/* Concatenate type signatures at compile time */
+template <size_t N, typename... Ts>
+struct descr {
+    char text[N + 1];
+
+    constexpr descr() : text{'\0'} { }
+    constexpr descr(char const (&s)[N+1]) : descr(s, make_index_sequence<N>()) { }
+
+    template <size_t... Is>
+    constexpr descr(char const (&s)[N+1], index_sequence<Is...>) : text{s[Is]..., '\0'} { }
+
+    template <typename... Chars>
+    constexpr descr(char c, Chars... cs) : text{c, static_cast<char>(cs)..., '\0'} { }
+
+    static constexpr std::array<const std::type_info *, sizeof...(Ts) + 1> types() {
+        return {{&typeid(Ts)..., nullptr}};
+    }
+};
+
+template <size_t N1, size_t N2, typename... Ts1, typename... Ts2, size_t... Is1, size_t... Is2>
+constexpr descr<N1 + N2, Ts1..., Ts2...> plus_impl(const descr<N1, Ts1...> &a, const descr<N2, Ts2...> &b,
+                                                   index_sequence<Is1...>, index_sequence<Is2...>) {
+    return {a.text[Is1]..., b.text[Is2]...};
+}
+
+template <size_t N1, size_t N2, typename... Ts1, typename... Ts2>
+constexpr descr<N1 + N2, Ts1..., Ts2...> operator+(const descr<N1, Ts1...> &a, const descr<N2, Ts2...> &b) {
+    return plus_impl(a, b, make_index_sequence<N1>(), make_index_sequence<N2>());
+}
+
+template <size_t N>
+constexpr descr<N - 1> _(char const(&text)[N]) { return descr<N - 1>(text); }
+constexpr descr<0> _(char const(&)[1]) { return {}; }
+
+template <size_t Rem, size_t... Digits> struct int_to_str : int_to_str<Rem/10, Rem%10, Digits...> { };
+template <size_t...Digits> struct int_to_str<0, Digits...> {
+    static constexpr auto digits = descr<sizeof...(Digits)>(('0' + Digits)...);
+};
+
+// Ternary description (like std::conditional)
+template <bool B, size_t N1, size_t N2>
+constexpr enable_if_t<B, descr<N1 - 1>> _(char const(&text1)[N1], char const(&)[N2]) {
+    return _(text1);
+}
+template <bool B, size_t N1, size_t N2>
+constexpr enable_if_t<!B, descr<N2 - 1>> _(char const(&)[N1], char const(&text2)[N2]) {
+    return _(text2);
+}
+
+template <bool B, typename T1, typename T2>
+constexpr enable_if_t<B, T1> _(const T1 &d, const T2 &) { return d; }
+template <bool B, typename T1, typename T2>
+constexpr enable_if_t<!B, T2> _(const T1 &, const T2 &d) { return d; }
+
+template <size_t Size> auto constexpr _() -> decltype(int_to_str<Size / 10, Size % 10>::digits) {
+    return int_to_str<Size / 10, Size % 10>::digits;
+}
+
+template <typename Type> constexpr descr<1, Type> _() { return {'%'}; }
+
+constexpr descr<0> concat() { return {}; }
+
+template <size_t N, typename... Ts>
+constexpr descr<N, Ts...> concat(const descr<N, Ts...> &descr) { return descr; }
+
+template <size_t N, typename... Ts, typename... Args>
+constexpr auto concat(const descr<N, Ts...> &d, const Args &...args)
+    -> decltype(std::declval<descr<N + 2, Ts...>>() + concat(args...)) {
+    return d + _(", ") + concat(args...);
+}
+
+template <size_t N, typename... Ts>
+constexpr descr<N + 2, Ts...> type_descr(const descr<N, Ts...> &descr) {
+    return _("{") + descr + _("}");
+}
+
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/detail/init.h b/libs/pybind/pybind11/detail/init.h
new file mode 100644
index 0000000000..3ef78c1179
--- /dev/null
+++ b/libs/pybind/pybind11/detail/init.h
@@ -0,0 +1,336 @@
+/*
+    pybind11/detail/init.h: init factory function implementation and support code.
+
+    Copyright (c) 2017 Jason Rhinelander <jason@imaginary.ca>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "class.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+template <>
+class type_caster<value_and_holder> {
+public:
+    bool load(handle h, bool) {
+        value = reinterpret_cast<value_and_holder *>(h.ptr());
+        return true;
+    }
+
+    template <typename> using cast_op_type = value_and_holder &;
+    operator value_and_holder &() { return *value; }
+    static constexpr auto name = _<value_and_holder>();
+
+private:
+    value_and_holder *value = nullptr;
+};
+
+PYBIND11_NAMESPACE_BEGIN(initimpl)
+
+inline void no_nullptr(void *ptr) {
+    if (!ptr) throw type_error("pybind11::init(): factory function returned nullptr");
+}
+
+// Implementing functions for all forms of py::init<...> and py::init(...)
+template <typename Class> using Cpp = typename Class::type;
+template <typename Class> using Alias = typename Class::type_alias;
+template <typename Class> using Holder = typename Class::holder_type;
+
+template <typename Class> using is_alias_constructible = std::is_constructible<Alias<Class>, Cpp<Class> &&>;
+
+// Takes a Cpp pointer and returns true if it actually is a polymorphic Alias instance.
+template <typename Class, enable_if_t<Class::has_alias, int> = 0>
+bool is_alias(Cpp<Class> *ptr) {
+    return dynamic_cast<Alias<Class> *>(ptr) != nullptr;
+}
+// Failing fallback version of the above for a no-alias class (always returns false)
+template <typename /*Class*/>
+constexpr bool is_alias(void *) { return false; }
+
+// Constructs and returns a new object; if the given arguments don't map to a constructor, we fall
+// back to brace aggregate initiailization so that for aggregate initialization can be used with
+// py::init, e.g.  `py::init<int, int>` to initialize a `struct T { int a; int b; }`.  For
+// non-aggregate types, we need to use an ordinary T(...) constructor (invoking as `T{...}` usually
+// works, but will not do the expected thing when `T` has an `initializer_list<T>` constructor).
+template <typename Class, typename... Args, detail::enable_if_t<std::is_constructible<Class, Args...>::value, int> = 0>
+inline Class *construct_or_initialize(Args &&...args) { return new Class(std::forward<Args>(args)...); }
+template <typename Class, typename... Args, detail::enable_if_t<!std::is_constructible<Class, Args...>::value, int> = 0>
+inline Class *construct_or_initialize(Args &&...args) { return new Class{std::forward<Args>(args)...}; }
+
+// Attempts to constructs an alias using a `Alias(Cpp &&)` constructor.  This allows types with
+// an alias to provide only a single Cpp factory function as long as the Alias can be
+// constructed from an rvalue reference of the base Cpp type.  This means that Alias classes
+// can, when appropriate, simply define a `Alias(Cpp &&)` constructor rather than needing to
+// inherit all the base class constructors.
+template <typename Class>
+void construct_alias_from_cpp(std::true_type /*is_alias_constructible*/,
+                              value_and_holder &v_h, Cpp<Class> &&base) {
+    v_h.value_ptr() = new Alias<Class>(std::move(base));
+}
+template <typename Class>
+[[noreturn]] void construct_alias_from_cpp(std::false_type /*!is_alias_constructible*/,
+                                           value_and_holder &, Cpp<Class> &&) {
+    throw type_error("pybind11::init(): unable to convert returned instance to required "
+                     "alias class: no `Alias<Class>(Class &&)` constructor available");
+}
+
+// Error-generating fallback for factories that don't match one of the below construction
+// mechanisms.
+template <typename Class>
+void construct(...) {
+    static_assert(!std::is_same<Class, Class>::value /* always false */,
+            "pybind11::init(): init function must return a compatible pointer, "
+            "holder, or value");
+}
+
+// Pointer return v1: the factory function returns a class pointer for a registered class.
+// If we don't need an alias (because this class doesn't have one, or because the final type is
+// inherited on the Python side) we can simply take over ownership.  Otherwise we need to try to
+// construct an Alias from the returned base instance.
+template <typename Class>
+void construct(value_and_holder &v_h, Cpp<Class> *ptr, bool need_alias) {
+    no_nullptr(ptr);
+    if (Class::has_alias && need_alias && !is_alias<Class>(ptr)) {
+        // We're going to try to construct an alias by moving the cpp type.  Whether or not
+        // that succeeds, we still need to destroy the original cpp pointer (either the
+        // moved away leftover, if the alias construction works, or the value itself if we
+        // throw an error), but we can't just call `delete ptr`: it might have a special
+        // deleter, or might be shared_from_this.  So we construct a holder around it as if
+        // it was a normal instance, then steal the holder away into a local variable; thus
+        // the holder and destruction happens when we leave the C++ scope, and the holder
+        // class gets to handle the destruction however it likes.
+        v_h.value_ptr() = ptr;
+        v_h.set_instance_registered(true); // To prevent init_instance from registering it
+        v_h.type->init_instance(v_h.inst, nullptr); // Set up the holder
+        Holder<Class> temp_holder(std::move(v_h.holder<Holder<Class>>())); // Steal the holder
+        v_h.type->dealloc(v_h); // Destroys the moved-out holder remains, resets value ptr to null
+        v_h.set_instance_registered(false);
+
+        construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(*ptr));
+    } else {
+        // Otherwise the type isn't inherited, so we don't need an Alias
+        v_h.value_ptr() = ptr;
+    }
+}
+
+// Pointer return v2: a factory that always returns an alias instance ptr.  We simply take over
+// ownership of the pointer.
+template <typename Class, enable_if_t<Class::has_alias, int> = 0>
+void construct(value_and_holder &v_h, Alias<Class> *alias_ptr, bool) {
+    no_nullptr(alias_ptr);
+    v_h.value_ptr() = static_cast<Cpp<Class> *>(alias_ptr);
+}
+
+// Holder return: copy its pointer, and move or copy the returned holder into the new instance's
+// holder.  This also handles types like std::shared_ptr<T> and std::unique_ptr<T> where T is a
+// derived type (through those holder's implicit conversion from derived class holder constructors).
+template <typename Class>
+void construct(value_and_holder &v_h, Holder<Class> holder, bool need_alias) {
+    auto *ptr = holder_helper<Holder<Class>>::get(holder);
+    no_nullptr(ptr);
+    // If we need an alias, check that the held pointer is actually an alias instance
+    if (Class::has_alias && need_alias && !is_alias<Class>(ptr))
+        throw type_error("pybind11::init(): construction failed: returned holder-wrapped instance "
+                         "is not an alias instance");
+
+    v_h.value_ptr() = ptr;
+    v_h.type->init_instance(v_h.inst, &holder);
+}
+
+// return-by-value version 1: returning a cpp class by value.  If the class has an alias and an
+// alias is required the alias must have an `Alias(Cpp &&)` constructor so that we can construct
+// the alias from the base when needed (i.e. because of Python-side inheritance).  When we don't
+// need it, we simply move-construct the cpp value into a new instance.
+template <typename Class>
+void construct(value_and_holder &v_h, Cpp<Class> &&result, bool need_alias) {
+    static_assert(std::is_move_constructible<Cpp<Class>>::value,
+        "pybind11::init() return-by-value factory function requires a movable class");
+    if (Class::has_alias && need_alias)
+        construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(result));
+    else
+        v_h.value_ptr() = new Cpp<Class>(std::move(result));
+}
+
+// return-by-value version 2: returning a value of the alias type itself.  We move-construct an
+// Alias instance (even if no the python-side inheritance is involved).  The is intended for
+// cases where Alias initialization is always desired.
+template <typename Class>
+void construct(value_and_holder &v_h, Alias<Class> &&result, bool) {
+    static_assert(std::is_move_constructible<Alias<Class>>::value,
+        "pybind11::init() return-by-alias-value factory function requires a movable alias class");
+    v_h.value_ptr() = new Alias<Class>(std::move(result));
+}
+
+// Implementing class for py::init<...>()
+template <typename... Args>
+struct constructor {
+    template <typename Class, typename... Extra, enable_if_t<!Class::has_alias, int> = 0>
+    static void execute(Class &cl, const Extra&... extra) {
+        cl.def("__init__", [](value_and_holder &v_h, Args... args) {
+            v_h.value_ptr() = construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
+        }, is_new_style_constructor(), extra...);
+    }
+
+    template <typename Class, typename... Extra,
+              enable_if_t<Class::has_alias &&
+                          std::is_constructible<Cpp<Class>, Args...>::value, int> = 0>
+    static void execute(Class &cl, const Extra&... extra) {
+        cl.def("__init__", [](value_and_holder &v_h, Args... args) {
+            if (Py_TYPE(v_h.inst) == v_h.type->type)
+                v_h.value_ptr() = construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
+            else
+                v_h.value_ptr() = construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
+        }, is_new_style_constructor(), extra...);
+    }
+
+    template <typename Class, typename... Extra,
+              enable_if_t<Class::has_alias &&
+                          !std::is_constructible<Cpp<Class>, Args...>::value, int> = 0>
+    static void execute(Class &cl, const Extra&... extra) {
+        cl.def("__init__", [](value_and_holder &v_h, Args... args) {
+            v_h.value_ptr() = construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
+        }, is_new_style_constructor(), extra...);
+    }
+};
+
+// Implementing class for py::init_alias<...>()
+template <typename... Args> struct alias_constructor {
+    template <typename Class, typename... Extra,
+              enable_if_t<Class::has_alias && std::is_constructible<Alias<Class>, Args...>::value, int> = 0>
+    static void execute(Class &cl, const Extra&... extra) {
+        cl.def("__init__", [](value_and_holder &v_h, Args... args) {
+            v_h.value_ptr() = construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
+        }, is_new_style_constructor(), extra...);
+    }
+};
+
+// Implementation class for py::init(Func) and py::init(Func, AliasFunc)
+template <typename CFunc, typename AFunc = void_type (*)(),
+          typename = function_signature_t<CFunc>, typename = function_signature_t<AFunc>>
+struct factory;
+
+// Specialization for py::init(Func)
+template <typename Func, typename Return, typename... Args>
+struct factory<Func, void_type (*)(), Return(Args...)> {
+    remove_reference_t<Func> class_factory;
+
+    factory(Func &&f) : class_factory(std::forward<Func>(f)) { }
+
+    // The given class either has no alias or has no separate alias factory;
+    // this always constructs the class itself.  If the class is registered with an alias
+    // type and an alias instance is needed (i.e. because the final type is a Python class
+    // inheriting from the C++ type) the returned value needs to either already be an alias
+    // instance, or the alias needs to be constructible from a `Class &&` argument.
+    template <typename Class, typename... Extra>
+    void execute(Class &cl, const Extra &...extra) && {
+        #if defined(PYBIND11_CPP14)
+        cl.def("__init__", [func = std::move(class_factory)]
+        #else
+        auto &func = class_factory;
+        cl.def("__init__", [func]
+        #endif
+        (value_and_holder &v_h, Args... args) {
+            construct<Class>(v_h, func(std::forward<Args>(args)...),
+                             Py_TYPE(v_h.inst) != v_h.type->type);
+        }, is_new_style_constructor(), extra...);
+    }
+};
+
+// Specialization for py::init(Func, AliasFunc)
+template <typename CFunc, typename AFunc,
+          typename CReturn, typename... CArgs, typename AReturn, typename... AArgs>
+struct factory<CFunc, AFunc, CReturn(CArgs...), AReturn(AArgs...)> {
+    static_assert(sizeof...(CArgs) == sizeof...(AArgs),
+                  "pybind11::init(class_factory, alias_factory): class and alias factories "
+                  "must have identical argument signatures");
+    static_assert(all_of<std::is_same<CArgs, AArgs>...>::value,
+                  "pybind11::init(class_factory, alias_factory): class and alias factories "
+                  "must have identical argument signatures");
+
+    remove_reference_t<CFunc> class_factory;
+    remove_reference_t<AFunc> alias_factory;
+
+    factory(CFunc &&c, AFunc &&a)
+        : class_factory(std::forward<CFunc>(c)), alias_factory(std::forward<AFunc>(a)) { }
+
+    // The class factory is called when the `self` type passed to `__init__` is the direct
+    // class (i.e. not inherited), the alias factory when `self` is a Python-side subtype.
+    template <typename Class, typename... Extra>
+    void execute(Class &cl, const Extra&... extra) && {
+        static_assert(Class::has_alias, "The two-argument version of `py::init()` can "
+                                        "only be used if the class has an alias");
+        #if defined(PYBIND11_CPP14)
+        cl.def("__init__", [class_func = std::move(class_factory), alias_func = std::move(alias_factory)]
+        #else
+        auto &class_func = class_factory;
+        auto &alias_func = alias_factory;
+        cl.def("__init__", [class_func, alias_func]
+        #endif
+        (value_and_holder &v_h, CArgs... args) {
+            if (Py_TYPE(v_h.inst) == v_h.type->type)
+                // If the instance type equals the registered type we don't have inheritance, so
+                // don't need the alias and can construct using the class function:
+                construct<Class>(v_h, class_func(std::forward<CArgs>(args)...), false);
+            else
+                construct<Class>(v_h, alias_func(std::forward<CArgs>(args)...), true);
+        }, is_new_style_constructor(), extra...);
+    }
+};
+
+/// Set just the C++ state. Same as `__init__`.
+template <typename Class, typename T>
+void setstate(value_and_holder &v_h, T &&result, bool need_alias) {
+    construct<Class>(v_h, std::forward<T>(result), need_alias);
+}
+
+/// Set both the C++ and Python states
+template <typename Class, typename T, typename O,
+          enable_if_t<std::is_convertible<O, handle>::value, int> = 0>
+void setstate(value_and_holder &v_h, std::pair<T, O> &&result, bool need_alias) {
+    construct<Class>(v_h, std::move(result.first), need_alias);
+    setattr((PyObject *) v_h.inst, "__dict__", result.second);
+}
+
+/// Implementation for py::pickle(GetState, SetState)
+template <typename Get, typename Set,
+          typename = function_signature_t<Get>, typename = function_signature_t<Set>>
+struct pickle_factory;
+
+template <typename Get, typename Set,
+          typename RetState, typename Self, typename NewInstance, typename ArgState>
+struct pickle_factory<Get, Set, RetState(Self), NewInstance(ArgState)> {
+    static_assert(std::is_same<intrinsic_t<RetState>, intrinsic_t<ArgState>>::value,
+                  "The type returned by `__getstate__` must be the same "
+                  "as the argument accepted by `__setstate__`");
+
+    remove_reference_t<Get> get;
+    remove_reference_t<Set> set;
+
+    pickle_factory(Get get, Set set)
+        : get(std::forward<Get>(get)), set(std::forward<Set>(set)) { }
+
+    template <typename Class, typename... Extra>
+    void execute(Class &cl, const Extra &...extra) && {
+        cl.def("__getstate__", std::move(get));
+
+#if defined(PYBIND11_CPP14)
+        cl.def("__setstate__", [func = std::move(set)]
+#else
+        auto &func = set;
+        cl.def("__setstate__", [func]
+#endif
+        (value_and_holder &v_h, ArgState state) {
+            setstate<Class>(v_h, func(std::forward<ArgState>(state)),
+                            Py_TYPE(v_h.inst) != v_h.type->type);
+        }, is_new_style_constructor(), extra...);
+    }
+};
+
+PYBIND11_NAMESPACE_END(initimpl)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(pybind11)
diff --git a/libs/pybind/pybind11/detail/internals.h b/libs/pybind/pybind11/detail/internals.h
new file mode 100644
index 0000000000..a455715bfd
--- /dev/null
+++ b/libs/pybind/pybind11/detail/internals.h
@@ -0,0 +1,363 @@
+/*
+    pybind11/detail/internals.h: Internal data structure and related functions
+
+    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "../pytypes.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+// Forward declarations
+inline PyTypeObject *make_static_property_type();
+inline PyTypeObject *make_default_metaclass();
+inline PyObject *make_object_base_type(PyTypeObject *metaclass);
+
+// The old Python Thread Local Storage (TLS) API is deprecated in Python 3.7 in favor of the new
+// Thread Specific Storage (TSS) API.
+#if PY_VERSION_HEX >= 0x03070000
+#    define PYBIND11_TLS_KEY_INIT(var) Py_tss_t *var = nullptr
+#    define PYBIND11_TLS_GET_VALUE(key) PyThread_tss_get((key))
+#    define PYBIND11_TLS_REPLACE_VALUE(key, value) PyThread_tss_set((key), (value))
+#    define PYBIND11_TLS_DELETE_VALUE(key) PyThread_tss_set((key), nullptr)
+#    define PYBIND11_TLS_FREE(key) PyThread_tss_free(key)
+#else
+    // Usually an int but a long on Cygwin64 with Python 3.x
+#    define PYBIND11_TLS_KEY_INIT(var) decltype(PyThread_create_key()) var = 0
+#    define PYBIND11_TLS_GET_VALUE(key) PyThread_get_key_value((key))
+#    if PY_MAJOR_VERSION < 3
+#        define PYBIND11_TLS_DELETE_VALUE(key)                               \
+             PyThread_delete_key_value(key)
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value)                       \
+             do {                                                            \
+                 PyThread_delete_key_value((key));                           \
+                 PyThread_set_key_value((key), (value));                     \
+             } while (false)
+#    else
+#        define PYBIND11_TLS_DELETE_VALUE(key)                               \
+             PyThread_set_key_value((key), nullptr)
+#        define PYBIND11_TLS_REPLACE_VALUE(key, value)                       \
+             PyThread_set_key_value((key), (value))
+#    endif
+#    define PYBIND11_TLS_FREE(key) (void)key
+#endif
+
+// Python loads modules by default with dlopen with the RTLD_LOCAL flag; under libc++ and possibly
+// other STLs, this means `typeid(A)` from one module won't equal `typeid(A)` from another module
+// even when `A` is the same, non-hidden-visibility type (e.g. from a common include).  Under
+// libstdc++, this doesn't happen: equality and the type_index hash are based on the type name,
+// which works.  If not under a known-good stl, provide our own name-based hash and equality
+// functions that use the type name.
+#if defined(__GLIBCXX__)
+inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) { return lhs == rhs; }
+using type_hash = std::hash<std::type_index>;
+using type_equal_to = std::equal_to<std::type_index>;
+#else
+inline bool same_type(const std::type_info &lhs, const std::type_info &rhs) {
+    return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
+}
+
+struct type_hash {
+    size_t operator()(const std::type_index &t) const {
+        size_t hash = 5381;
+        const char *ptr = t.name();
+        while (auto c = static_cast<unsigned char>(*ptr++))
+            hash = (hash * 33) ^ c;
+        return hash;
+    }
+};
+
+struct type_equal_to {
+    bool operator()(const std::type_index &lhs, const std::type_index &rhs) const {
+        return lhs.name() == rhs.name() || std::strcmp(lhs.name(), rhs.name()) == 0;
+    }
+};
+#endif
+
+template <typename value_type>
+using type_map = std::unordered_map<std::type_index, value_type, type_hash, type_equal_to>;
+
+struct override_hash {
+    inline size_t operator()(const std::pair<const PyObject *, const char *>& v) const {
+        size_t value = std::hash<const void *>()(v.first);
+        value ^= std::hash<const void *>()(v.second) + 0x9e3779b9 + (value<<6) + (value>>2);
+        return value;
+    }
+};
+
+/// Internal data structure used to track registered instances and types.
+/// Whenever binary incompatible changes are made to this structure,
+/// `PYBIND11_INTERNALS_VERSION` must be incremented.
+struct internals {
+    type_map<type_info *> registered_types_cpp; // std::type_index -> pybind11's type information
+    std::unordered_map<PyTypeObject *, std::vector<type_info *>> registered_types_py; // PyTypeObject* -> base type_info(s)
+    std::unordered_multimap<const void *, instance*> registered_instances; // void * -> instance*
+    std::unordered_set<std::pair<const PyObject *, const char *>, override_hash> inactive_override_cache;
+    type_map<std::vector<bool (*)(PyObject *, void *&)>> direct_conversions;
+    std::unordered_map<const PyObject *, std::vector<PyObject *>> patients;
+    std::forward_list<void (*) (std::exception_ptr)> registered_exception_translators;
+    std::unordered_map<std::string, void *> shared_data; // Custom data to be shared across extensions
+    std::vector<PyObject *> loader_patient_stack; // Used by `loader_life_support`
+    std::forward_list<std::string> static_strings; // Stores the std::strings backing detail::c_str()
+    PyTypeObject *static_property_type;
+    PyTypeObject *default_metaclass;
+    PyObject *instance_base;
+#if defined(WITH_THREAD)
+    PYBIND11_TLS_KEY_INIT(tstate);
+    PyInterpreterState *istate = nullptr;
+    ~internals() {
+        // This destructor is called *after* Py_Finalize() in finalize_interpreter().
+        // That *SHOULD BE* fine. The following details what happens whe PyThread_tss_free is called.
+        // PYBIND11_TLS_FREE is PyThread_tss_free on python 3.7+. On older python, it does nothing.
+        // PyThread_tss_free calls PyThread_tss_delete and PyMem_RawFree.
+        // PyThread_tss_delete just calls TlsFree (on Windows) or pthread_key_delete (on *NIX). Neither
+        // of those have anything to do with CPython internals.
+        // PyMem_RawFree *requires* that the `tstate` be allocated with the CPython allocator.
+        PYBIND11_TLS_FREE(tstate);
+    }
+#endif
+};
+
+/// Additional type information which does not fit into the PyTypeObject.
+/// Changes to this struct also require bumping `PYBIND11_INTERNALS_VERSION`.
+struct type_info {
+    PyTypeObject *type;
+    const std::type_info *cpptype;
+    size_t type_size, type_align, holder_size_in_ptrs;
+    void *(*operator_new)(size_t);
+    void (*init_instance)(instance *, const void *);
+    void (*dealloc)(value_and_holder &v_h);
+    std::vector<PyObject *(*)(PyObject *, PyTypeObject *)> implicit_conversions;
+    std::vector<std::pair<const std::type_info *, void *(*)(void *)>> implicit_casts;
+    std::vector<bool (*)(PyObject *, void *&)> *direct_conversions;
+    buffer_info *(*get_buffer)(PyObject *, void *) = nullptr;
+    void *get_buffer_data = nullptr;
+    void *(*module_local_load)(PyObject *, const type_info *) = nullptr;
+    /* A simple type never occurs as a (direct or indirect) parent
+     * of a class that makes use of multiple inheritance */
+    bool simple_type : 1;
+    /* True if there is no multiple inheritance in this type's inheritance tree */
+    bool simple_ancestors : 1;
+    /* for base vs derived holder_type checks */
+    bool default_holder : 1;
+    /* true if this is a type registered with py::module_local */
+    bool module_local : 1;
+};
+
+/// Tracks the `internals` and `type_info` ABI version independent of the main library version
+#define PYBIND11_INTERNALS_VERSION 4
+
+/// On MSVC, debug and release builds are not ABI-compatible!
+#if defined(_MSC_VER) && defined(_DEBUG)
+#  define PYBIND11_BUILD_TYPE "_debug"
+#else
+#  define PYBIND11_BUILD_TYPE ""
+#endif
+
+/// Let's assume that different compilers are ABI-incompatible.
+/// A user can manually set this string if they know their
+/// compiler is compatible.
+#ifndef PYBIND11_COMPILER_TYPE
+#  if defined(_MSC_VER)
+#    define PYBIND11_COMPILER_TYPE "_msvc"
+#  elif defined(__INTEL_COMPILER)
+#    define PYBIND11_COMPILER_TYPE "_icc"
+#  elif defined(__clang__)
+#    define PYBIND11_COMPILER_TYPE "_clang"
+#  elif defined(__PGI)
+#    define PYBIND11_COMPILER_TYPE "_pgi"
+#  elif defined(__MINGW32__)
+#    define PYBIND11_COMPILER_TYPE "_mingw"
+#  elif defined(__CYGWIN__)
+#    define PYBIND11_COMPILER_TYPE "_gcc_cygwin"
+#  elif defined(__GNUC__)
+#    define PYBIND11_COMPILER_TYPE "_gcc"
+#  else
+#    define PYBIND11_COMPILER_TYPE "_unknown"
+#  endif
+#endif
+
+/// Also standard libs
+#ifndef PYBIND11_STDLIB
+#  if defined(_LIBCPP_VERSION)
+#    define PYBIND11_STDLIB "_libcpp"
+#  elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
+#    define PYBIND11_STDLIB "_libstdcpp"
+#  else
+#    define PYBIND11_STDLIB ""
+#  endif
+#endif
+
+/// On Linux/OSX, changes in __GXX_ABI_VERSION__ indicate ABI incompatibility.
+#ifndef PYBIND11_BUILD_ABI
+#  if defined(__GXX_ABI_VERSION)
+#    define PYBIND11_BUILD_ABI "_cxxabi" PYBIND11_TOSTRING(__GXX_ABI_VERSION)
+#  else
+#    define PYBIND11_BUILD_ABI ""
+#  endif
+#endif
+
+#ifndef PYBIND11_INTERNALS_KIND
+#  if defined(WITH_THREAD)
+#    define PYBIND11_INTERNALS_KIND ""
+#  else
+#    define PYBIND11_INTERNALS_KIND "_without_thread"
+#  endif
+#endif
+
+#define PYBIND11_INTERNALS_ID "__pybind11_internals_v" \
+    PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
+
+#define PYBIND11_MODULE_LOCAL_ID "__pybind11_module_local_v" \
+    PYBIND11_TOSTRING(PYBIND11_INTERNALS_VERSION) PYBIND11_INTERNALS_KIND PYBIND11_COMPILER_TYPE PYBIND11_STDLIB PYBIND11_BUILD_ABI PYBIND11_BUILD_TYPE "__"
+
+/// Each module locally stores a pointer to the `internals` data. The data
+/// itself is shared among modules with the same `PYBIND11_INTERNALS_ID`.
+inline internals **&get_internals_pp() {
+    static internals **internals_pp = nullptr;
+    return internals_pp;
+}
+
+inline void translate_exception(std::exception_ptr p) {
+    try {
+        if (p) std::rethrow_exception(p);
+    } catch (error_already_set &e)           { e.restore();                                    return;
+    } catch (const builtin_exception &e)     { e.set_error();                                  return;
+    } catch (const std::bad_alloc &e)        { PyErr_SetString(PyExc_MemoryError,   e.what()); return;
+    } catch (const std::domain_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
+    } catch (const std::invalid_argument &e) { PyErr_SetString(PyExc_ValueError,    e.what()); return;
+    } catch (const std::length_error &e)     { PyErr_SetString(PyExc_ValueError,    e.what()); return;
+    } catch (const std::out_of_range &e)     { PyErr_SetString(PyExc_IndexError,    e.what()); return;
+    } catch (const std::range_error &e)      { PyErr_SetString(PyExc_ValueError,    e.what()); return;
+    } catch (const std::overflow_error &e)   { PyErr_SetString(PyExc_OverflowError, e.what()); return;
+    } catch (const std::exception &e)        { PyErr_SetString(PyExc_RuntimeError,  e.what()); return;
+    } catch (...) {
+        PyErr_SetString(PyExc_RuntimeError, "Caught an unknown exception!");
+        return;
+    }
+}
+
+#if !defined(__GLIBCXX__)
+inline void translate_local_exception(std::exception_ptr p) {
+    try {
+        if (p) std::rethrow_exception(p);
+    } catch (error_already_set &e)       { e.restore();   return;
+    } catch (const builtin_exception &e) { e.set_error(); return;
+    }
+}
+#endif
+
+/// Return a reference to the current `internals` data
+PYBIND11_NOINLINE inline internals &get_internals() {
+    auto **&internals_pp = get_internals_pp();
+    if (internals_pp && *internals_pp)
+        return **internals_pp;
+
+    // Ensure that the GIL is held since we will need to make Python calls.
+    // Cannot use py::gil_scoped_acquire here since that constructor calls get_internals.
+    struct gil_scoped_acquire_local {
+        gil_scoped_acquire_local() : state (PyGILState_Ensure()) {}
+        ~gil_scoped_acquire_local() { PyGILState_Release(state); }
+        const PyGILState_STATE state;
+    } gil;
+
+    constexpr auto *id = PYBIND11_INTERNALS_ID;
+    auto builtins = handle(PyEval_GetBuiltins());
+    if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
+        internals_pp = static_cast<internals **>(capsule(builtins[id]));
+
+        // We loaded builtins through python's builtins, which means that our `error_already_set`
+        // and `builtin_exception` may be different local classes than the ones set up in the
+        // initial exception translator, below, so add another for our local exception classes.
+        //
+        // libstdc++ doesn't require this (types there are identified only by name)
+#if !defined(__GLIBCXX__)
+        (*internals_pp)->registered_exception_translators.push_front(&translate_local_exception);
+#endif
+    } else {
+        if (!internals_pp) internals_pp = new internals*();
+        auto *&internals_ptr = *internals_pp;
+        internals_ptr = new internals();
+#if defined(WITH_THREAD)
+
+        #if PY_VERSION_HEX < 0x03090000
+                PyEval_InitThreads();
+        #endif
+        PyThreadState *tstate = PyThreadState_Get();
+        #if PY_VERSION_HEX >= 0x03070000
+            internals_ptr->tstate = PyThread_tss_alloc();
+            if (!internals_ptr->tstate || PyThread_tss_create(internals_ptr->tstate))
+                pybind11_fail("get_internals: could not successfully initialize the TSS key!");
+            PyThread_tss_set(internals_ptr->tstate, tstate);
+        #else
+            internals_ptr->tstate = PyThread_create_key();
+            if (internals_ptr->tstate == -1)
+                pybind11_fail("get_internals: could not successfully initialize the TLS key!");
+            PyThread_set_key_value(internals_ptr->tstate, tstate);
+        #endif
+        internals_ptr->istate = tstate->interp;
+#endif
+        builtins[id] = capsule(internals_pp);
+        internals_ptr->registered_exception_translators.push_front(&translate_exception);
+        internals_ptr->static_property_type = make_static_property_type();
+        internals_ptr->default_metaclass = make_default_metaclass();
+        internals_ptr->instance_base = make_object_base_type(internals_ptr->default_metaclass);
+    }
+    return **internals_pp;
+}
+
+/// Works like `internals.registered_types_cpp`, but for module-local registered types:
+inline type_map<type_info *> &registered_local_types_cpp() {
+    static type_map<type_info *> locals{};
+    return locals;
+}
+
+/// Constructs a std::string with the given arguments, stores it in `internals`, and returns its
+/// `c_str()`.  Such strings objects have a long storage duration -- the internal strings are only
+/// cleared when the program exits or after interpreter shutdown (when embedding), and so are
+/// suitable for c-style strings needed by Python internals (such as PyTypeObject's tp_name).
+template <typename... Args>
+const char *c_str(Args &&...args) {
+    auto &strings = get_internals().static_strings;
+    strings.emplace_front(std::forward<Args>(args)...);
+    return strings.front().c_str();
+}
+
+PYBIND11_NAMESPACE_END(detail)
+
+/// Returns a named pointer that is shared among all extension modules (using the same
+/// pybind11 version) running in the current interpreter. Names starting with underscores
+/// are reserved for internal usage. Returns `nullptr` if no matching entry was found.
+inline PYBIND11_NOINLINE void *get_shared_data(const std::string &name) {
+    auto &internals = detail::get_internals();
+    auto it = internals.shared_data.find(name);
+    return it != internals.shared_data.end() ? it->second : nullptr;
+}
+
+/// Set the shared data that can be later recovered by `get_shared_data()`.
+inline PYBIND11_NOINLINE void *set_shared_data(const std::string &name, void *data) {
+    detail::get_internals().shared_data[name] = data;
+    return data;
+}
+
+/// Returns a typed reference to a shared data entry (by using `get_shared_data()`) if
+/// such entry exists. Otherwise, a new object of default-constructible type `T` is
+/// added to the shared data under the given name and a reference to it is returned.
+template<typename T>
+T &get_or_create_shared_data(const std::string &name) {
+    auto &internals = detail::get_internals();
+    auto it = internals.shared_data.find(name);
+    T *ptr = (T *) (it != internals.shared_data.end() ? it->second : nullptr);
+    if (!ptr) {
+        ptr = new T();
+        internals.shared_data[name] = ptr;
+    }
+    return *ptr;
+}
+
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/typeid.h b/libs/pybind/pybind11/detail/typeid.h
similarity index 83%
rename from libs/pybind/pybind11/typeid.h
rename to libs/pybind/pybind11/detail/typeid.h
index c903fb14cb..148889ffef 100644
--- a/libs/pybind/pybind11/typeid.h
+++ b/libs/pybind/pybind11/detail/typeid.h
@@ -1,5 +1,5 @@
 /*
-    pybind11/typeid.h: Compiler-independent access to type identifiers
+    pybind11/detail/typeid.h: Compiler-independent access to type identifiers
 
     Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
 
@@ -16,8 +16,10 @@
 #include <cxxabi.h>
 #endif
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+#include "common.h"
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 /// Erase all occurrences of a substring
 inline void erase_all(std::string &string, const std::string &search) {
     for (size_t pos = 0;;) {
@@ -41,7 +43,7 @@ PYBIND11_NOINLINE inline void clean_type_id(std::string &name) {
 #endif
     detail::erase_all(name, "pybind11::");
 }
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 /// Return a string representation of a C++ type
 template <typename T> static std::string type_id() {
@@ -50,4 +52,4 @@ template <typename T> static std::string type_id() {
     return name;
 }
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/eigen.h b/libs/pybind/pybind11/eigen.h
index 6abe8c48fb..e8c6f63391 100644
--- a/libs/pybind/pybind11/eigen.h
+++ b/libs/pybind/pybind11/eigen.h
@@ -17,32 +17,38 @@
 #  pragma GCC diagnostic push
 #  pragma GCC diagnostic ignored "-Wconversion"
 #  pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#  ifdef __clang__
+//   Eigen generates a bunch of implicit-copy-constructor-is-deprecated warnings with -Wdeprecated
+//   under Clang, so disable that warning here:
+#    pragma GCC diagnostic ignored "-Wdeprecated"
+#  endif
 #  if __GNUC__ >= 7
 #    pragma GCC diagnostic ignored "-Wint-in-bool-context"
 #  endif
 #endif
 
-#include <Eigen/Core>
-#include <Eigen/SparseCore>
-
 #if defined(_MSC_VER)
 #  pragma warning(push)
 #  pragma warning(disable: 4127) // warning C4127: Conditional expression is constant
+#  pragma warning(disable: 4996) // warning C4996: std::unary_negate is deprecated in C++17
 #endif
 
+#include <Eigen/Core>
+#include <Eigen/SparseCore>
+
 // Eigen prior to 3.2.7 doesn't have proper move constructors--but worse, some classes get implicit
 // move constructors that break things.  We could detect this an explicitly copy, but an extra copy
 // of matrices seems highly undesirable.
 static_assert(EIGEN_VERSION_AT_LEAST(3,2,7), "Eigen support in pybind11 requires Eigen >= 3.2.7");
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 // Provide a convenience alias for easier pass-by-ref usage with fully dynamic strides:
 using EigenDStride = Eigen::Stride<Eigen::Dynamic, Eigen::Dynamic>;
 template <typename MatrixType> using EigenDRef = Eigen::Ref<MatrixType, 0, EigenDStride>;
 template <typename MatrixType> using EigenDMap = Eigen::Map<MatrixType, 0, EigenDStride>;
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 #if EIGEN_VERSION_AT_LEAST(3,3,0)
 using EigenIndex = Eigen::Index;
@@ -68,16 +74,22 @@ template <typename T> using is_eigen_other = all_of<
 template <bool EigenRowMajor> struct EigenConformable {
     bool conformable = false;
     EigenIndex rows = 0, cols = 0;
-    EigenDStride stride{0, 0};
+    EigenDStride stride{0, 0};      // Only valid if negativestrides is false!
+    bool negativestrides = false;   // If true, do not use stride!
 
     EigenConformable(bool fits = false) : conformable{fits} {}
     // Matrix type:
     EigenConformable(EigenIndex r, EigenIndex c,
             EigenIndex rstride, EigenIndex cstride) :
-        conformable{true}, rows{r}, cols{c},
-        stride(EigenRowMajor ? rstride : cstride /* outer stride */,
-               EigenRowMajor ? cstride : rstride /* inner stride */)
-        {}
+        conformable{true}, rows{r}, cols{c} {
+        // TODO: when Eigen bug #747 is fixed, remove the tests for non-negativity. http://eigen.tuxfamily.org/bz/show_bug.cgi?id=747
+        if (rstride < 0 || cstride < 0) {
+            negativestrides = true;
+        } else {
+            stride = {EigenRowMajor ? rstride : cstride /* outer stride */,
+                      EigenRowMajor ? cstride : rstride /* inner stride */ };
+        }
+    }
     // Vector type:
     EigenConformable(EigenIndex r, EigenIndex c, EigenIndex stride)
         : EigenConformable(r, c, r == 1 ? c*stride : stride, c == 1 ? r : r*stride) {}
@@ -86,6 +98,7 @@ template <bool EigenRowMajor> struct EigenConformable {
         // To have compatible strides, we need (on both dimensions) one of fully dynamic strides,
         // matching strides, or a dimension size of 1 (in which case the stride value is irrelevant)
         return
+            !negativestrides &&
             (props::inner_stride == Eigen::Dynamic || props::inner_stride == stride.inner() ||
                 (EigenRowMajor ? cols : rows) == 1) &&
             (props::outer_stride == Eigen::Dynamic || props::outer_stride == stride.outer() ||
@@ -138,8 +151,8 @@ template <typename Type_> struct EigenProps {
             EigenIndex
                 np_rows = a.shape(0),
                 np_cols = a.shape(1),
-                np_rstride = a.strides(0) / sizeof(Scalar),
-                np_cstride = a.strides(1) / sizeof(Scalar);
+                np_rstride = a.strides(0) / static_cast<ssize_t>(sizeof(Scalar)),
+                np_cstride = a.strides(1) / static_cast<ssize_t>(sizeof(Scalar));
             if ((fixed_rows && np_rows != rows) || (fixed_cols && np_cols != cols))
                 return false;
 
@@ -149,7 +162,7 @@ template <typename Type_> struct EigenProps {
         // Otherwise we're storing an n-vector.  Only one of the strides will be used, but whichever
         // is used, we want the (single) numpy stride value.
         const EigenIndex n = a.shape(0),
-              stride = a.strides(0) / sizeof(Scalar);
+              stride = a.strides(0) / static_cast<ssize_t>(sizeof(Scalar));
 
         if (vector) { // Eigen type is a compile-time vector
             if (fixed && size != n)
@@ -173,13 +186,13 @@ template <typename Type_> struct EigenProps {
         }
     }
 
-    static PYBIND11_DESCR descriptor() {
-        constexpr bool show_writeable = is_eigen_dense_map<Type>::value && is_eigen_mutable_map<Type>::value;
-        constexpr bool show_order = is_eigen_dense_map<Type>::value;
-        constexpr bool show_c_contiguous = show_order && requires_row_major;
-        constexpr bool show_f_contiguous = !show_c_contiguous && show_order && requires_col_major;
+    static constexpr bool show_writeable = is_eigen_dense_map<Type>::value && is_eigen_mutable_map<Type>::value;
+    static constexpr bool show_order = is_eigen_dense_map<Type>::value;
+    static constexpr bool show_c_contiguous = show_order && requires_row_major;
+    static constexpr bool show_f_contiguous = !show_c_contiguous && show_order && requires_col_major;
 
-    return _("numpy.ndarray[") + npy_format_descriptor<Scalar>::name() +
+    static constexpr auto descriptor =
+        _("numpy.ndarray[") + npy_format_descriptor<Scalar>::name +
         _("[")  + _<fixed_rows>(_<(size_t) rows>(), _("m")) +
         _(", ") + _<fixed_cols>(_<(size_t) cols>(), _("n")) +
         _("]") +
@@ -193,25 +206,19 @@ template <typename Type_> struct EigenProps {
         _<show_c_contiguous>(", flags.c_contiguous", "") +
         _<show_f_contiguous>(", flags.f_contiguous", "") +
         _("]");
-    }
 };
 
 // Casts an Eigen type to numpy array.  If given a base, the numpy array references the src data,
 // otherwise it'll make a copy.  writeable lets you turn off the writeable flag for the array.
 template <typename props> handle eigen_array_cast(typename props::Type const &src, handle base = handle(), bool writeable = true) {
-    constexpr size_t elem_size = sizeof(typename props::Scalar);
-    std::vector<size_t> shape, strides;
-    if (props::vector) {
-        shape.push_back(src.size());
-        strides.push_back(elem_size * src.innerStride());
-    }
-    else {
-        shape.push_back(src.rows());
-        shape.push_back(src.cols());
-        strides.push_back(elem_size * src.rowStride());
-        strides.push_back(elem_size * src.colStride());
-    }
-    array a(std::move(shape), std::move(strides), src.data(), base);
+    constexpr ssize_t elem_size = sizeof(typename props::Scalar);
+    array a;
+    if (props::vector)
+        a = array({ src.size() }, { elem_size * src.innerStride() }, src.data(), base);
+    else
+        a = array({ src.rows(), src.cols() }, { elem_size * src.rowStride(), elem_size * src.colStride() },
+                  src.data(), base);
+
     if (!writeable)
         array_proxy(a.ptr())->flags &= ~detail::npy_api::NPY_ARRAY_WRITEABLE_;
 
@@ -246,8 +253,14 @@ struct type_caster<Type, enable_if_t<is_eigen_dense_plain<Type>::value>> {
     using Scalar = typename Type::Scalar;
     using props = EigenProps<Type>;
 
-    bool load(handle src, bool) {
-        auto buf = array_t<Scalar>::ensure(src);
+    bool load(handle src, bool convert) {
+        // If we're in no-convert mode, only load if given an array of the correct type
+        if (!convert && !isinstance<array_t<Scalar>>(src))
+            return false;
+
+        // Coerce into an array, but don't do type conversion yet; the copy below handles it.
+        auto buf = array::ensure(src);
+
         if (!buf)
             return false;
 
@@ -257,9 +270,20 @@ struct type_caster<Type, enable_if_t<is_eigen_dense_plain<Type>::value>> {
 
         auto fits = props::conformable(buf);
         if (!fits)
-            return false; // Non-comformable vector/matrix types
+            return false;
+
+        // Allocate the new type, then build a numpy reference into it
+        value = Type(fits.rows, fits.cols);
+        auto ref = reinterpret_steal<array>(eigen_ref_array<props>(value));
+        if (dims == 1) ref = ref.squeeze();
+        else if (ref.ndim() == 1) buf = buf.squeeze();
 
-        value = Eigen::Map<const Type, 0, EigenDStride>(buf.data(), fits.rows, fits.cols, fits.stride);
+        int result = detail::npy_api::get().PyArray_CopyInto_(ref.ptr(), buf.ptr());
+
+        if (result < 0) { // Copy failed!
+            PyErr_Clear();
+            return false;
+        }
 
         return true;
     }
@@ -318,24 +342,17 @@ struct type_caster<Type, enable_if_t<is_eigen_dense_plain<Type>::value>> {
         return cast_impl(src, policy, parent);
     }
 
-    static PYBIND11_DESCR name() { return type_descr(props::descriptor()); }
+    static constexpr auto name = props::descriptor;
 
     operator Type*() { return &value; }
     operator Type&() { return value; }
-    template <typename T> using cast_op_type = cast_op_type<T>;
+    operator Type&&() && { return std::move(value); }
+    template <typename T> using cast_op_type = movable_cast_op_type<T>;
 
 private:
     Type value;
 };
 
-// Eigen Ref/Map classes have slightly different policy requirements, meaning we don't want to force
-// `move` when a Ref/Map rvalue is returned; we treat Ref<> sort of like a pointer (we care about
-// the underlying data, not the outer shell).
-template <typename Return>
-struct return_value_policy_override<Return, enable_if_t<is_eigen_dense_map<Return>::value>> {
-    static return_value_policy policy(return_value_policy p) { return p; }
-};
-
 // Base class for casting reference/map/block/etc. objects back to python.
 template <typename MapType> struct eigen_map_caster {
 private:
@@ -365,7 +382,7 @@ template <typename MapType> struct eigen_map_caster {
         }
     }
 
-    static PYBIND11_DESCR name() { return props::descriptor(); }
+    static constexpr auto name = props::descriptor;
 
     // Explicitly delete these: support python -> C++ conversion on these (i.e. these can be return
     // types but not bound arguments).  We still provide them (with an explicitly delete) so that
@@ -415,7 +432,7 @@ struct type_caster<
         if (!need_copy) {
             // We don't need a converting copy, but we also need to check whether the strides are
             // compatible with the Ref's stride requirements
-            Array aref = reinterpret_borrow<Array>(src);
+            auto aref = reinterpret_borrow<Array>(src);
 
             if (aref && (!need_writeable || aref.writeable())) {
                 fits = props::conformable(aref);
@@ -442,6 +459,7 @@ struct type_caster<
             if (!fits || !fits.template stride_compatible<props>())
                 return false;
             copy_or_ref = std::move(copy);
+            loader_life_support::add_patient(copy_or_ref);
         }
 
         ref.reset();
@@ -509,7 +527,7 @@ struct type_caster<Type, enable_if_t<is_eigen_other<Type>::value>> {
     }
     static handle cast(const Type *src, return_value_policy policy, handle parent) { return cast(*src, policy, parent); }
 
-    static PYBIND11_DESCR name() { return props::descriptor(); }
+    static constexpr auto name = props::descriptor;
 
     // Explicitly delete these: support python -> C++ conversion on these (i.e. these can be return
     // types but not bound arguments).  We still provide them (with an explicitly delete) so that
@@ -521,9 +539,9 @@ struct type_caster<Type, enable_if_t<is_eigen_other<Type>::value>> {
 
 template<typename Type>
 struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
-    typedef typename Type::Scalar Scalar;
-    typedef typename std::remove_reference<decltype(*std::declval<Type>().outerIndexPtr())>::type StorageIndex;
-    typedef typename Type::Index Index;
+    using Scalar = typename Type::Scalar;
+    using StorageIndex = remove_reference_t<decltype(*std::declval<Type>().outerIndexPtr())>;
+    using Index = typename Type::Index;
     static constexpr bool rowMajor = Type::IsRowMajor;
 
     bool load(handle src, bool) {
@@ -531,11 +549,11 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
             return false;
 
         auto obj = reinterpret_borrow<object>(src);
-        object sparse_module = module::import("scipy.sparse");
+        object sparse_module = module_::import("scipy.sparse");
         object matrix_type = sparse_module.attr(
             rowMajor ? "csr_matrix" : "csc_matrix");
 
-        if (obj.get_type() != matrix_type.ptr()) {
+        if (!type::handle_of(obj).is(matrix_type)) {
             try {
                 obj = matrix_type(obj);
             } catch (const error_already_set &) {
@@ -562,12 +580,12 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
     static handle cast(const Type &src, return_value_policy /* policy */, handle /* parent */) {
         const_cast<Type&>(src).makeCompressed();
 
-        object matrix_type = module::import("scipy.sparse").attr(
+        object matrix_type = module_::import("scipy.sparse").attr(
             rowMajor ? "csr_matrix" : "csc_matrix");
 
-        array data((size_t) src.nonZeros(), src.valuePtr());
-        array outerIndices((size_t) (rowMajor ? src.rows() : src.cols()) + 1, src.outerIndexPtr());
-        array innerIndices((size_t) src.nonZeros(), src.innerIndexPtr());
+        array data(src.nonZeros(), src.valuePtr());
+        array outerIndices((rowMajor ? src.rows() : src.cols()) + 1, src.outerIndexPtr());
+        array innerIndices(src.nonZeros(), src.innerIndexPtr());
 
         return matrix_type(
             std::make_tuple(data, innerIndices, outerIndices),
@@ -576,11 +594,11 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
     }
 
     PYBIND11_TYPE_CASTER(Type, _<(Type::IsRowMajor) != 0>("scipy.sparse.csr_matrix[", "scipy.sparse.csc_matrix[")
-            + npy_format_descriptor<Scalar>::name() + _("]"));
+            + npy_format_descriptor<Scalar>::name + _("]"));
 };
 
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
 #if defined(__GNUG__) || defined(__clang__)
 #  pragma GCC diagnostic pop
diff --git a/libs/pybind/pybind11/embed.h b/libs/pybind/pybind11/embed.h
new file mode 100644
index 0000000000..204aaf989f
--- /dev/null
+++ b/libs/pybind/pybind11/embed.h
@@ -0,0 +1,201 @@
+/*
+    pybind11/embed.h: Support for embedding the interpreter
+
+    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "pybind11.h"
+#include "eval.h"
+
+#if defined(PYPY_VERSION)
+#  error Embedding the interpreter is not supported with PyPy
+#endif
+
+#if PY_MAJOR_VERSION >= 3
+#  define PYBIND11_EMBEDDED_MODULE_IMPL(name)            \
+      extern "C" PyObject *pybind11_init_impl_##name();  \
+      extern "C" PyObject *pybind11_init_impl_##name() { \
+          return pybind11_init_wrapper_##name();         \
+      }
+#else
+#  define PYBIND11_EMBEDDED_MODULE_IMPL(name)            \
+      extern "C" void pybind11_init_impl_##name();       \
+      extern "C" void pybind11_init_impl_##name() {      \
+          pybind11_init_wrapper_##name();                \
+      }
+#endif
+
+/** \rst
+    Add a new module to the table of builtins for the interpreter. Must be
+    defined in global scope. The first macro parameter is the name of the
+    module (without quotes). The second parameter is the variable which will
+    be used as the interface to add functions and classes to the module.
+
+    .. code-block:: cpp
+
+        PYBIND11_EMBEDDED_MODULE(example, m) {
+            // ... initialize functions and classes here
+            m.def("foo", []() {
+                return "Hello, World!";
+            });
+        }
+ \endrst */
+#define PYBIND11_EMBEDDED_MODULE(name, variable)                                \
+    static ::pybind11::module_::module_def                                      \
+        PYBIND11_CONCAT(pybind11_module_def_, name);                            \
+    static void PYBIND11_CONCAT(pybind11_init_, name)(::pybind11::module_ &);   \
+    static PyObject PYBIND11_CONCAT(*pybind11_init_wrapper_, name)() {          \
+        auto m = ::pybind11::module_::create_extension_module(                  \
+            PYBIND11_TOSTRING(name), nullptr,                                   \
+            &PYBIND11_CONCAT(pybind11_module_def_, name));                      \
+        try {                                                                   \
+            PYBIND11_CONCAT(pybind11_init_, name)(m);                           \
+            return m.ptr();                                                     \
+        } PYBIND11_CATCH_INIT_EXCEPTIONS                                        \
+    }                                                                           \
+    PYBIND11_EMBEDDED_MODULE_IMPL(name)                                         \
+    ::pybind11::detail::embedded_module PYBIND11_CONCAT(pybind11_module_, name) \
+                              (PYBIND11_TOSTRING(name),                         \
+                               PYBIND11_CONCAT(pybind11_init_impl_, name));     \
+    void PYBIND11_CONCAT(pybind11_init_, name)(::pybind11::module_ &variable)
+
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+/// Python 2.7/3.x compatible version of `PyImport_AppendInittab` and error checks.
+struct embedded_module {
+#if PY_MAJOR_VERSION >= 3
+    using init_t = PyObject *(*)();
+#else
+    using init_t = void (*)();
+#endif
+    embedded_module(const char *name, init_t init) {
+        if (Py_IsInitialized())
+            pybind11_fail("Can't add new modules after the interpreter has been initialized");
+
+        auto result = PyImport_AppendInittab(name, init);
+        if (result == -1)
+            pybind11_fail("Insufficient memory to add a new module");
+    }
+};
+
+PYBIND11_NAMESPACE_END(detail)
+
+/** \rst
+    Initialize the Python interpreter. No other pybind11 or CPython API functions can be
+    called before this is done; with the exception of `PYBIND11_EMBEDDED_MODULE`. The
+    optional parameter can be used to skip the registration of signal handlers (see the
+    `Python documentation`_ for details). Calling this function again after the interpreter
+    has already been initialized is a fatal error.
+
+    If initializing the Python interpreter fails, then the program is terminated.  (This
+    is controlled by the CPython runtime and is an exception to pybind11's normal behavior
+    of throwing exceptions on errors.)
+
+    .. _Python documentation: https://docs.python.org/3/c-api/init.html#c.Py_InitializeEx
+ \endrst */
+inline void initialize_interpreter(bool init_signal_handlers = true) {
+    if (Py_IsInitialized())
+        pybind11_fail("The interpreter is already running");
+
+    Py_InitializeEx(init_signal_handlers ? 1 : 0);
+
+    // Make .py files in the working directory available by default
+    module_::import("sys").attr("path").cast<list>().append(".");
+}
+
+/** \rst
+    Shut down the Python interpreter. No pybind11 or CPython API functions can be called
+    after this. In addition, pybind11 objects must not outlive the interpreter:
+
+    .. code-block:: cpp
+
+        { // BAD
+            py::initialize_interpreter();
+            auto hello = py::str("Hello, World!");
+            py::finalize_interpreter();
+        } // <-- BOOM, hello's destructor is called after interpreter shutdown
+
+        { // GOOD
+            py::initialize_interpreter();
+            { // scoped
+                auto hello = py::str("Hello, World!");
+            } // <-- OK, hello is cleaned up properly
+            py::finalize_interpreter();
+        }
+
+        { // BETTER
+            py::scoped_interpreter guard{};
+            auto hello = py::str("Hello, World!");
+        }
+
+    .. warning::
+
+        The interpreter can be restarted by calling `initialize_interpreter` again.
+        Modules created using pybind11 can be safely re-initialized. However, Python
+        itself cannot completely unload binary extension modules and there are several
+        caveats with regard to interpreter restarting. All the details can be found
+        in the CPython documentation. In short, not all interpreter memory may be
+        freed, either due to reference cycles or user-created global data.
+
+ \endrst */
+inline void finalize_interpreter() {
+    handle builtins(PyEval_GetBuiltins());
+    const char *id = PYBIND11_INTERNALS_ID;
+
+    // Get the internals pointer (without creating it if it doesn't exist).  It's possible for the
+    // internals to be created during Py_Finalize() (e.g. if a py::capsule calls `get_internals()`
+    // during destruction), so we get the pointer-pointer here and check it after Py_Finalize().
+    detail::internals **internals_ptr_ptr = detail::get_internals_pp();
+    // It could also be stashed in builtins, so look there too:
+    if (builtins.contains(id) && isinstance<capsule>(builtins[id]))
+        internals_ptr_ptr = capsule(builtins[id]);
+
+    Py_Finalize();
+
+    if (internals_ptr_ptr) {
+        delete *internals_ptr_ptr;
+        *internals_ptr_ptr = nullptr;
+    }
+}
+
+/** \rst
+    Scope guard version of `initialize_interpreter` and `finalize_interpreter`.
+    This a move-only guard and only a single instance can exist.
+
+    .. code-block:: cpp
+
+        #include <pybind11/embed.h>
+
+        int main() {
+            py::scoped_interpreter guard{};
+            py::print(Hello, World!);
+        } // <-- interpreter shutdown
+ \endrst */
+class scoped_interpreter {
+public:
+    scoped_interpreter(bool init_signal_handlers = true) {
+        initialize_interpreter(init_signal_handlers);
+    }
+
+    scoped_interpreter(const scoped_interpreter &) = delete;
+    scoped_interpreter(scoped_interpreter &&other) noexcept { other.is_valid = false; }
+    scoped_interpreter &operator=(const scoped_interpreter &) = delete;
+    scoped_interpreter &operator=(scoped_interpreter &&) = delete;
+
+    ~scoped_interpreter() {
+        if (is_valid)
+            finalize_interpreter();
+    }
+
+private:
+    bool is_valid = true;
+};
+
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/eval.h b/libs/pybind/pybind11/eval.h
index 5b2b98272d..fa6b8af479 100644
--- a/libs/pybind/pybind11/eval.h
+++ b/libs/pybind/pybind11/eval.h
@@ -11,11 +11,25 @@
 
 #pragma once
 
-#pragma once
-
 #include "pybind11.h"
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+inline void ensure_builtins_in_globals(object &global) {
+    #if PY_VERSION_HEX < 0x03080000
+        // Running exec and eval on Python 2 and 3 adds `builtins` module under
+        // `__builtins__` key to globals if not yet present.
+        // Python 3.8 made PyRun_String behave similarly. Let's also do that for
+        // older versions, for consistency.
+        if (!global.contains("__builtins__"))
+            global["__builtins__"] = module_::import(PYBIND11_BUILTINS_MODULE);
+    #else
+        (void) global;
+    #endif
+}
+
+PYBIND11_NAMESPACE_END(detail)
 
 enum eval_mode {
     /// Evaluate a string containing an isolated expression
@@ -29,15 +43,12 @@ enum eval_mode {
 };
 
 template <eval_mode mode = eval_expr>
-object eval(str expr, object global = object(), object local = object()) {
-    if (!global) {
-        global = reinterpret_borrow<object>(PyEval_GetGlobals());
-        if (!global)
-            global = dict();
-    }
+object eval(str expr, object global = globals(), object local = object()) {
     if (!local)
         local = global;
 
+    detail::ensure_builtins_in_globals(global);
+
     /* PyRun_String does not accept a PyObject / encoding specifier,
        this seems to be the only alternative */
     std::string buffer = "# -*- coding: utf-8 -*-\n" + (std::string) expr;
@@ -56,16 +67,44 @@ object eval(str expr, object global = object(), object local = object()) {
     return reinterpret_steal<object>(result);
 }
 
+template <eval_mode mode = eval_expr, size_t N>
+object eval(const char (&s)[N], object global = globals(), object local = object()) {
+    /* Support raw string literals by removing common leading whitespace */
+    auto expr = (s[0] == '\n') ? str(module_::import("textwrap").attr("dedent")(s))
+                               : str(s);
+    return eval<mode>(expr, global, local);
+}
+
+inline void exec(str expr, object global = globals(), object local = object()) {
+    eval<eval_statements>(expr, global, local);
+}
+
+template <size_t N>
+void exec(const char (&s)[N], object global = globals(), object local = object()) {
+    eval<eval_statements>(s, global, local);
+}
+
+#if defined(PYPY_VERSION) && PY_VERSION_HEX >= 0x03000000
 template <eval_mode mode = eval_statements>
-object eval_file(str fname, object global = object(), object local = object()) {
-    if (!global) {
-        global = reinterpret_borrow<object>(PyEval_GetGlobals());
-        if (!global)
-            global = dict();
-    }
+object eval_file(str, object, object) {
+    pybind11_fail("eval_file not supported in PyPy3. Use eval");
+}
+template <eval_mode mode = eval_statements>
+object eval_file(str, object) {
+    pybind11_fail("eval_file not supported in PyPy3. Use eval");
+}
+template <eval_mode mode = eval_statements>
+object eval_file(str) {
+    pybind11_fail("eval_file not supported in PyPy3. Use eval");
+}
+#else
+template <eval_mode mode = eval_statements>
+object eval_file(str fname, object global = globals(), object local = object()) {
     if (!local)
         local = global;
 
+    detail::ensure_builtins_in_globals(global);
+
     int start;
     switch (mode) {
         case eval_expr:             start = Py_eval_input;   break;
@@ -108,5 +147,6 @@ object eval_file(str fname, object global = object(), object local = object()) {
         throw error_already_set();
     return reinterpret_steal<object>(result);
 }
+#endif
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/functional.h b/libs/pybind/pybind11/functional.h
index a99ee737f4..92c17dc225 100644
--- a/libs/pybind/pybind11/functional.h
+++ b/libs/pybind/pybind11/functional.h
@@ -12,8 +12,8 @@
 #include "pybind11.h"
 #include <functional>
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 template <typename Return, typename... Args>
 struct type_caster<std::function<Return(Args...)>> {
@@ -22,14 +22,18 @@ struct type_caster<std::function<Return(Args...)>> {
     using function_type = Return (*) (Args...);
 
 public:
-    bool load(handle src_, bool) {
-        if (src_.is_none())
+    bool load(handle src, bool convert) {
+        if (src.is_none()) {
+            // Defer accepting None to other overloads (if we aren't in convert mode):
+            if (!convert) return false;
             return true;
+        }
 
-        src_ = detail::get_function(src_);
-        if (!src_ || !PyCallable_Check(src_.ptr()))
+        if (!isinstance<function>(src))
             return false;
 
+        auto func = reinterpret_borrow<function>(src);
+
         /*
            When passing a C++ function as an argument to another C++
            function via Python, every function call would normally involve
@@ -38,24 +42,45 @@ struct type_caster<std::function<Return(Args...)>> {
            stateless (i.e. function pointer or lambda function without
            captured variables), in which case the roundtrip can be avoided.
          */
-        if (PyCFunction_Check(src_.ptr())) {
-            auto c = reinterpret_borrow<capsule>(PyCFunction_GET_SELF(src_.ptr()));
+        if (auto cfunc = func.cpp_function()) {
+            auto c = reinterpret_borrow<capsule>(PyCFunction_GET_SELF(cfunc.ptr()));
             auto rec = (function_record *) c;
 
-            if (rec && rec->is_stateless && rec->data[1] == &typeid(function_type)) {
+            if (rec && rec->is_stateless &&
+                    same_type(typeid(function_type), *reinterpret_cast<const std::type_info *>(rec->data[1]))) {
                 struct capture { function_type f; };
                 value = ((capture *) &rec->data)->f;
                 return true;
             }
         }
 
-        auto src = reinterpret_borrow<object>(src_);
-        value = [src](Args... args) -> Return {
-            gil_scoped_acquire acq;
-            object retval(src(std::forward<Args>(args)...));
-            /* Visual studio 2015 parser issue: need parentheses around this expression */
-            return (retval.template cast<Return>());
+        // ensure GIL is held during functor destruction
+        struct func_handle {
+            function f;
+            func_handle(function&& f_) : f(std::move(f_)) {}
+            func_handle(const func_handle& f_) {
+                gil_scoped_acquire acq;
+                f = f_.f;
+            }
+            ~func_handle() {
+                gil_scoped_acquire acq;
+                function kill_f(std::move(f));
+            }
+        };
+
+        // to emulate 'move initialization capture' in C++11
+        struct func_wrapper {
+            func_handle hfunc;
+            func_wrapper(func_handle&& hf): hfunc(std::move(hf)) {}
+            Return operator()(Args... args) const {
+                gil_scoped_acquire acq;
+                object retval(hfunc.f(std::forward<Args>(args)...));
+                /* Visual studio 2015 parser issue: need parentheses around this expression */
+                return (retval.template cast<Return>());
+            }
         };
+
+        value = func_wrapper(func_handle(std::move(func)));
         return true;
     }
 
@@ -71,11 +96,9 @@ struct type_caster<std::function<Return(Args...)>> {
             return cpp_function(std::forward<Func>(f_), policy).release();
     }
 
-    PYBIND11_TYPE_CASTER(type, _("Callable[[") +
-            argument_loader<Args...>::arg_names() + _("], ") +
-            make_caster<retval_type>::name() +
-            _("]"));
+    PYBIND11_TYPE_CASTER(type, _("Callable[[") + concat(make_caster<Args>::name...) + _("], ")
+                               + make_caster<retval_type>::name + _("]"));
 };
 
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/iostream.h b/libs/pybind/pybind11/iostream.h
new file mode 100644
index 0000000000..5e9a8143d0
--- /dev/null
+++ b/libs/pybind/pybind11/iostream.h
@@ -0,0 +1,216 @@
+/*
+    pybind11/iostream.h -- Tools to assist with redirecting cout and cerr to Python
+
+    Copyright (c) 2017 Henry F. Schreiner
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#pragma once
+
+#include "pybind11.h"
+
+#include <streambuf>
+#include <ostream>
+#include <string>
+#include <memory>
+#include <iostream>
+
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+// Buffer that writes to Python instead of C++
+class pythonbuf : public std::streambuf {
+private:
+    using traits_type = std::streambuf::traits_type;
+
+    const size_t buf_size;
+    std::unique_ptr<char[]> d_buffer;
+    object pywrite;
+    object pyflush;
+
+    int overflow(int c) override {
+        if (!traits_type::eq_int_type(c, traits_type::eof())) {
+            *pptr() = traits_type::to_char_type(c);
+            pbump(1);
+        }
+        return sync() == 0 ? traits_type::not_eof(c) : traits_type::eof();
+    }
+
+    // This function must be non-virtual to be called in a destructor. If the
+    // rare MSVC test failure shows up with this version, then this should be
+    // simplified to a fully qualified call.
+    int _sync() {
+        if (pbase() != pptr()) {
+            // This subtraction cannot be negative, so dropping the sign
+            str line(pbase(), static_cast<size_t>(pptr() - pbase()));
+
+            {
+                gil_scoped_acquire tmp;
+                pywrite(line);
+                pyflush();
+            }
+
+            setp(pbase(), epptr());
+        }
+        return 0;
+    }
+
+    int sync() override {
+        return _sync();
+    }
+
+public:
+
+    pythonbuf(object pyostream, size_t buffer_size = 1024)
+        : buf_size(buffer_size),
+          d_buffer(new char[buf_size]),
+          pywrite(pyostream.attr("write")),
+          pyflush(pyostream.attr("flush")) {
+        setp(d_buffer.get(), d_buffer.get() + buf_size - 1);
+    }
+
+    pythonbuf(pythonbuf&&) = default;
+
+    /// Sync before destroy
+    ~pythonbuf() override {
+        _sync();
+    }
+};
+
+PYBIND11_NAMESPACE_END(detail)
+
+
+/** \rst
+    This a move-only guard that redirects output.
+
+    .. code-block:: cpp
+
+        #include <pybind11/iostream.h>
+
+        ...
+
+        {
+            py::scoped_ostream_redirect output;
+            std::cout << "Hello, World!"; // Python stdout
+        } // <-- return std::cout to normal
+
+    You can explicitly pass the c++ stream and the python object,
+    for example to guard stderr instead.
+
+    .. code-block:: cpp
+
+        {
+            py::scoped_ostream_redirect output{std::cerr, py::module_::import("sys").attr("stderr")};
+            std::cerr << "Hello, World!";
+        }
+ \endrst */
+class scoped_ostream_redirect {
+protected:
+    std::streambuf *old;
+    std::ostream &costream;
+    detail::pythonbuf buffer;
+
+public:
+    scoped_ostream_redirect(
+            std::ostream &costream = std::cout,
+            object pyostream = module_::import("sys").attr("stdout"))
+        : costream(costream), buffer(pyostream) {
+        old = costream.rdbuf(&buffer);
+    }
+
+    ~scoped_ostream_redirect() {
+        costream.rdbuf(old);
+    }
+
+    scoped_ostream_redirect(const scoped_ostream_redirect &) = delete;
+    scoped_ostream_redirect(scoped_ostream_redirect &&other) = default;
+    scoped_ostream_redirect &operator=(const scoped_ostream_redirect &) = delete;
+    scoped_ostream_redirect &operator=(scoped_ostream_redirect &&) = delete;
+};
+
+
+/** \rst
+    Like `scoped_ostream_redirect`, but redirects cerr by default. This class
+    is provided primary to make ``py::call_guard`` easier to make.
+
+    .. code-block:: cpp
+
+     m.def("noisy_func", &noisy_func,
+           py::call_guard<scoped_ostream_redirect,
+                          scoped_estream_redirect>());
+
+\endrst */
+class scoped_estream_redirect : public scoped_ostream_redirect {
+public:
+    scoped_estream_redirect(
+            std::ostream &costream = std::cerr,
+            object pyostream = module_::import("sys").attr("stderr"))
+        : scoped_ostream_redirect(costream,pyostream) {}
+};
+
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+// Class to redirect output as a context manager. C++ backend.
+class OstreamRedirect {
+    bool do_stdout_;
+    bool do_stderr_;
+    std::unique_ptr<scoped_ostream_redirect> redirect_stdout;
+    std::unique_ptr<scoped_estream_redirect> redirect_stderr;
+
+public:
+    OstreamRedirect(bool do_stdout = true, bool do_stderr = true)
+        : do_stdout_(do_stdout), do_stderr_(do_stderr) {}
+
+    void enter() {
+        if (do_stdout_)
+            redirect_stdout.reset(new scoped_ostream_redirect());
+        if (do_stderr_)
+            redirect_stderr.reset(new scoped_estream_redirect());
+    }
+
+    void exit() {
+        redirect_stdout.reset();
+        redirect_stderr.reset();
+    }
+};
+
+PYBIND11_NAMESPACE_END(detail)
+
+/** \rst
+    This is a helper function to add a C++ redirect context manager to Python
+    instead of using a C++ guard. To use it, add the following to your binding code:
+
+    .. code-block:: cpp
+
+        #include <pybind11/iostream.h>
+
+        ...
+
+        py::add_ostream_redirect(m, "ostream_redirect");
+
+    You now have a Python context manager that redirects your output:
+
+    .. code-block:: python
+
+        with m.ostream_redirect():
+            m.print_to_cout_function()
+
+    This manager can optionally be told which streams to operate on:
+
+    .. code-block:: python
+
+        with m.ostream_redirect(stdout=true, stderr=true):
+            m.noisy_function_with_error_printing()
+
+ \endrst */
+inline class_<detail::OstreamRedirect> add_ostream_redirect(module_ m, std::string name = "ostream_redirect") {
+    return class_<detail::OstreamRedirect>(m, name.c_str(), module_local())
+        .def(init<bool,bool>(), arg("stdout")=true, arg("stderr")=true)
+        .def("__enter__", &detail::OstreamRedirect::enter)
+        .def("__exit__", [](detail::OstreamRedirect &self_, args) { self_.exit(); });
+}
+
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/numpy.h b/libs/pybind/pybind11/numpy.h
index 3227a12eb2..019f5688e7 100644
--- a/libs/pybind/pybind11/numpy.h
+++ b/libs/pybind/pybind11/numpy.h
@@ -14,13 +14,15 @@
 #include <numeric>
 #include <algorithm>
 #include <array>
+#include <cstdint>
 #include <cstdlib>
 #include <cstring>
 #include <sstream>
 #include <string>
-#include <initializer_list>
 #include <functional>
+#include <type_traits>
 #include <utility>
+#include <vector>
 #include <typeindex>
 
 #if defined(_MSC_VER)
@@ -29,16 +31,21 @@
 #endif
 
 /* This will be true on all flat address space platforms and allows us to reduce the
-   whole npy_intp / size_t / Py_intptr_t business down to just size_t for all size
+   whole npy_intp / ssize_t / Py_intptr_t business down to just ssize_t for all size
    and dimension types (e.g. shape, strides, indexing), instead of inflicting this
    upon the library user. */
-static_assert(sizeof(size_t) == sizeof(Py_intptr_t), "size_t != Py_intptr_t");
+static_assert(sizeof(::pybind11::ssize_t) == sizeof(Py_intptr_t), "ssize_t != Py_intptr_t");
+static_assert(std::is_signed<Py_intptr_t>::value, "Py_intptr_t must be signed");
+// We now can reinterpret_cast between py::ssize_t and Py_intptr_t (MSVC + PyPy cares)
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 class array; // Forward declaration
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+template <> struct handle_type_name<array> { static constexpr auto name = _("numpy.ndarray"); };
+
 template <typename type, typename SFINAE = void> struct npy_format_descriptor;
 
 struct PyArrayDescr_Proxy {
@@ -108,6 +115,18 @@ inline numpy_internals& get_numpy_internals() {
     return *ptr;
 }
 
+template <typename T> struct same_size {
+    template <typename U> using as = bool_constant<sizeof(T) == sizeof(U)>;
+};
+
+template <typename Concrete> constexpr int platform_lookup() { return -1; }
+
+// Lookup a type according to its size, and return a value corresponding to the NumPy typenum.
+template <typename Concrete, typename T, typename... Ts, typename... Ints>
+constexpr int platform_lookup(int I, Ints... Is) {
+    return sizeof(Concrete) == sizeof(T) ? I : platform_lookup<Concrete, Ts...>(Is...);
+}
+
 struct npy_api {
     enum constants {
         NPY_ARRAY_C_CONTIGUOUS_ = 0x0001,
@@ -126,9 +145,30 @@ struct npy_api {
         NPY_FLOAT_, NPY_DOUBLE_, NPY_LONGDOUBLE_,
         NPY_CFLOAT_, NPY_CDOUBLE_, NPY_CLONGDOUBLE_,
         NPY_OBJECT_ = 17,
-        NPY_STRING_, NPY_UNICODE_, NPY_VOID_
+        NPY_STRING_, NPY_UNICODE_, NPY_VOID_,
+        // Platform-dependent normalization
+        NPY_INT8_ = NPY_BYTE_,
+        NPY_UINT8_ = NPY_UBYTE_,
+        NPY_INT16_ = NPY_SHORT_,
+        NPY_UINT16_ = NPY_USHORT_,
+        // `npy_common.h` defines the integer aliases. In order, it checks:
+        // NPY_BITSOF_LONG, NPY_BITSOF_LONGLONG, NPY_BITSOF_INT, NPY_BITSOF_SHORT, NPY_BITSOF_CHAR
+        // and assigns the alias to the first matching size, so we should check in this order.
+        NPY_INT32_ = platform_lookup<std::int32_t, long, int, short>(
+            NPY_LONG_, NPY_INT_, NPY_SHORT_),
+        NPY_UINT32_ = platform_lookup<std::uint32_t, unsigned long, unsigned int, unsigned short>(
+            NPY_ULONG_, NPY_UINT_, NPY_USHORT_),
+        NPY_INT64_ = platform_lookup<std::int64_t, long, long long, int>(
+            NPY_LONG_, NPY_LONGLONG_, NPY_INT_),
+        NPY_UINT64_ = platform_lookup<std::uint64_t, unsigned long, unsigned long long, unsigned int>(
+            NPY_ULONG_, NPY_ULONGLONG_, NPY_UINT_),
     };
 
+    typedef struct {
+        Py_intptr_t *ptr;
+        int len;
+    } PyArray_Dims;
+
     static npy_api& get() {
         static npy_api api = lookup();
         return api;
@@ -141,11 +181,14 @@ struct npy_api {
         return (bool) PyObject_TypeCheck(obj, PyArrayDescr_Type_);
     }
 
+    unsigned int (*PyArray_GetNDArrayCFeatureVersion_)();
     PyObject *(*PyArray_DescrFromType_)(int);
     PyObject *(*PyArray_NewFromDescr_)
-        (PyTypeObject *, PyObject *, int, Py_intptr_t *,
-         Py_intptr_t *, void *, int, PyObject *);
+        (PyTypeObject *, PyObject *, int, Py_intptr_t const *,
+         Py_intptr_t const *, void *, int, PyObject *);
+    // Unused. Not removed because that affects ABI of the class.
     PyObject *(*PyArray_DescrNewFromType_)(int);
+    int (*PyArray_CopyInto_)(PyObject *, PyObject *);
     PyObject *(*PyArray_NewCopy_)(PyObject *, int);
     PyTypeObject *PyArray_Type_;
     PyTypeObject *PyVoidArrType_Type_;
@@ -154,21 +197,26 @@ struct npy_api {
     PyObject *(*PyArray_FromAny_) (PyObject *, PyObject *, int, int, int, PyObject *);
     int (*PyArray_DescrConverter_) (PyObject *, PyObject **);
     bool (*PyArray_EquivTypes_) (PyObject *, PyObject *);
-    int (*PyArray_GetArrayParamsFromObject_)(PyObject *, PyObject *, char, PyObject **, int *,
-                                             Py_ssize_t *, PyObject **, PyObject *);
+    int (*PyArray_GetArrayParamsFromObject_)(PyObject *, PyObject *, unsigned char, PyObject **, int *,
+                                             Py_intptr_t *, PyObject **, PyObject *);
     PyObject *(*PyArray_Squeeze_)(PyObject *);
+    // Unused. Not removed because that affects ABI of the class.
     int (*PyArray_SetBaseObject_)(PyObject *, PyObject *);
+    PyObject* (*PyArray_Resize_)(PyObject*, PyArray_Dims*, int, int);
 private:
     enum functions {
+        API_PyArray_GetNDArrayCFeatureVersion = 211,
         API_PyArray_Type = 2,
         API_PyArrayDescr_Type = 3,
         API_PyVoidArrType_Type = 39,
         API_PyArray_DescrFromType = 45,
         API_PyArray_DescrFromScalar = 57,
         API_PyArray_FromAny = 69,
+        API_PyArray_Resize = 80,
+        API_PyArray_CopyInto = 82,
         API_PyArray_NewCopy = 85,
         API_PyArray_NewFromDescr = 94,
-        API_PyArray_DescrNewFromType = 9,
+        API_PyArray_DescrNewFromType = 96,
         API_PyArray_DescrConverter = 174,
         API_PyArray_EquivTypes = 182,
         API_PyArray_GetArrayParamsFromObject = 278,
@@ -177,7 +225,7 @@ struct npy_api {
     };
 
     static npy_api lookup() {
-        module m = module::import("numpy.core.multiarray");
+        module_ m = module_::import("numpy.core.multiarray");
         auto c = m.attr("_ARRAY_API");
 #if PY_MAJOR_VERSION >= 3
         void **api_ptr = (void **) PyCapsule_GetPointer(c.ptr(), NULL);
@@ -186,12 +234,17 @@ struct npy_api {
 #endif
         npy_api api;
 #define DECL_NPY_API(Func) api.Func##_ = (decltype(api.Func##_)) api_ptr[API_##Func];
+        DECL_NPY_API(PyArray_GetNDArrayCFeatureVersion);
+        if (api.PyArray_GetNDArrayCFeatureVersion_() < 0x7)
+            pybind11_fail("pybind11 numpy support requires numpy >= 1.7.0");
         DECL_NPY_API(PyArray_Type);
         DECL_NPY_API(PyVoidArrType_Type);
         DECL_NPY_API(PyArrayDescr_Type);
         DECL_NPY_API(PyArray_DescrFromType);
         DECL_NPY_API(PyArray_DescrFromScalar);
         DECL_NPY_API(PyArray_FromAny);
+        DECL_NPY_API(PyArray_Resize);
+        DECL_NPY_API(PyArray_CopyInto);
         DECL_NPY_API(PyArray_NewCopy);
         DECL_NPY_API(PyArray_NewFromDescr);
         DECL_NPY_API(PyArray_DescrNewFromType);
@@ -230,18 +283,68 @@ template <typename T, size_t N> struct is_std_array<std::array<T, N>> : std::tru
 template <typename T> struct is_complex : std::false_type { };
 template <typename T> struct is_complex<std::complex<T>> : std::true_type { };
 
+template <typename T> struct array_info_scalar {
+    using type = T;
+    static constexpr bool is_array = false;
+    static constexpr bool is_empty = false;
+    static constexpr auto extents = _("");
+    static void append_extents(list& /* shape */) { }
+};
+// Computes underlying type and a comma-separated list of extents for array
+// types (any mix of std::array and built-in arrays). An array of char is
+// treated as scalar because it gets special handling.
+template <typename T> struct array_info : array_info_scalar<T> { };
+template <typename T, size_t N> struct array_info<std::array<T, N>> {
+    using type = typename array_info<T>::type;
+    static constexpr bool is_array = true;
+    static constexpr bool is_empty = (N == 0) || array_info<T>::is_empty;
+    static constexpr size_t extent = N;
+
+    // appends the extents to shape
+    static void append_extents(list& shape) {
+        shape.append(N);
+        array_info<T>::append_extents(shape);
+    }
+
+    static constexpr auto extents = _<array_info<T>::is_array>(
+        concat(_<N>(), array_info<T>::extents), _<N>()
+    );
+};
+// For numpy we have special handling for arrays of characters, so we don't include
+// the size in the array extents.
+template <size_t N> struct array_info<char[N]> : array_info_scalar<char[N]> { };
+template <size_t N> struct array_info<std::array<char, N>> : array_info_scalar<std::array<char, N>> { };
+template <typename T, size_t N> struct array_info<T[N]> : array_info<std::array<T, N>> { };
+template <typename T> using remove_all_extents_t = typename array_info<T>::type;
+
 template <typename T> using is_pod_struct = all_of<
-    std::is_pod<T>, // since we're accessing directly in memory we need a POD type
+    std::is_standard_layout<T>,     // since we're accessing directly in memory we need a standard layout type
+#if !defined(__GNUG__) || defined(_LIBCPP_VERSION) || defined(_GLIBCXX_USE_CXX11_ABI)
+    // _GLIBCXX_USE_CXX11_ABI indicates that we're using libstdc++ from GCC 5 or newer, independent
+    // of the actual compiler (Clang can also use libstdc++, but it always defines __GNUC__ == 4).
+    std::is_trivially_copyable<T>,
+#else
+    // GCC 4 doesn't implement is_trivially_copyable, so approximate it
+    std::is_trivially_destructible<T>,
+    satisfies_any_of<T, std::has_trivial_copy_constructor, std::has_trivial_copy_assign>,
+#endif
     satisfies_none_of<T, std::is_reference, std::is_array, is_std_array, std::is_arithmetic, is_complex, std::is_enum>
 >;
 
-template <size_t Dim = 0, typename Strides> size_t byte_offset_unsafe(const Strides &) { return 0; }
-template <size_t Dim = 0, typename Strides, typename... Ix>
-size_t byte_offset_unsafe(const Strides &strides, size_t i, Ix... index) {
+// Replacement for std::is_pod (deprecated in C++20)
+template <typename T> using is_pod = all_of<
+    std::is_standard_layout<T>,
+    std::is_trivial<T>
+>;
+
+template <ssize_t Dim = 0, typename Strides> ssize_t byte_offset_unsafe(const Strides &) { return 0; }
+template <ssize_t Dim = 0, typename Strides, typename... Ix>
+ssize_t byte_offset_unsafe(const Strides &strides, ssize_t i, Ix... index) {
     return i * strides[Dim] + byte_offset_unsafe<Dim + 1>(strides, index...);
 }
 
-/** Proxy class providing unsafe, unchecked const access to array data.  This is constructed through
+/**
+ * Proxy class providing unsafe, unchecked const access to array data.  This is constructed through
  * the `unchecked<T, N>()` method of `array` or the `unchecked<N>()` method of `array_t<T>`.  `Dims`
  * will be -1 for dimensions determined at runtime.
  */
@@ -252,66 +355,68 @@ class unchecked_reference {
     const unsigned char *data_;
     // Storing the shape & strides in local variables (i.e. these arrays) allows the compiler to
     // make large performance gains on big, nested loops, but requires compile-time dimensions
-    conditional_t<Dynamic, const size_t *, std::array<size_t, (size_t) Dims>>
-        shape_, strides_;
-    const size_t dims_;
+    conditional_t<Dynamic, const ssize_t *, std::array<ssize_t, (size_t) Dims>>
+            shape_, strides_;
+    const ssize_t dims_;
 
     friend class pybind11::array;
     // Constructor for compile-time dimensions:
     template <bool Dyn = Dynamic>
-    unchecked_reference(const void *data, const size_t *shape, const size_t *strides, enable_if_t<!Dyn, size_t>)
+    unchecked_reference(const void *data, const ssize_t *shape, const ssize_t *strides, enable_if_t<!Dyn, ssize_t>)
     : data_{reinterpret_cast<const unsigned char *>(data)}, dims_{Dims} {
-        for (size_t i = 0; i < dims_; i++) {
+        for (size_t i = 0; i < (size_t) dims_; i++) {
             shape_[i] = shape[i];
             strides_[i] = strides[i];
         }
     }
     // Constructor for runtime dimensions:
     template <bool Dyn = Dynamic>
-    unchecked_reference(const void *data, const size_t *shape, const size_t *strides, enable_if_t<Dyn, size_t> dims)
+    unchecked_reference(const void *data, const ssize_t *shape, const ssize_t *strides, enable_if_t<Dyn, ssize_t> dims)
     : data_{reinterpret_cast<const unsigned char *>(data)}, shape_{shape}, strides_{strides}, dims_{dims} {}
 
 public:
-    /** Unchecked const reference access to data at the given indices.  For a compile-time known
+    /**
+     * Unchecked const reference access to data at the given indices.  For a compile-time known
      * number of dimensions, this requires the correct number of arguments; for run-time
      * dimensionality, this is not checked (and so is up to the caller to use safely).
      */
     template <typename... Ix> const T &operator()(Ix... index) const {
-        static_assert(sizeof...(Ix) == Dims || Dynamic,
+        static_assert(ssize_t{sizeof...(Ix)} == Dims || Dynamic,
                 "Invalid number of indices for unchecked array reference");
-        return *reinterpret_cast<const T *>(data_ + byte_offset_unsafe(strides_, size_t(index)...));
+        return *reinterpret_cast<const T *>(data_ + byte_offset_unsafe(strides_, ssize_t(index)...));
     }
-    /** Unchecked const reference access to data; this operator only participates if the reference
+    /**
+     * Unchecked const reference access to data; this operator only participates if the reference
      * is to a 1-dimensional array.  When present, this is exactly equivalent to `obj(index)`.
      */
-    template <size_t D = Dims, typename = enable_if_t<D == 1 || Dynamic>>
-    const T &operator[](size_t index) const { return operator()(index); }
+    template <ssize_t D = Dims, typename = enable_if_t<D == 1 || Dynamic>>
+    const T &operator[](ssize_t index) const { return operator()(index); }
 
     /// Pointer access to the data at the given indices.
-    template <typename... Ix> const T *data(Ix... ix) const { return &operator()(size_t(ix)...); }
+    template <typename... Ix> const T *data(Ix... ix) const { return &operator()(ssize_t(ix)...); }
 
     /// Returns the item size, i.e. sizeof(T)
-    constexpr static size_t itemsize() { return sizeof(T); }
+    constexpr static ssize_t itemsize() { return sizeof(T); }
 
     /// Returns the shape (i.e. size) of dimension `dim`
-    size_t shape(size_t dim) const { return shape_[dim]; }
+    ssize_t shape(ssize_t dim) const { return shape_[(size_t) dim]; }
 
     /// Returns the number of dimensions of the array
-    size_t ndim() const { return dims_; }
+    ssize_t ndim() const { return dims_; }
 
     /// Returns the total number of elements in the referenced array, i.e. the product of the shapes
     template <bool Dyn = Dynamic>
-    enable_if_t<!Dyn, size_t> size() const {
-        return std::accumulate(shape_.begin(), shape_.end(), (size_t) 1, std::multiplies<size_t>());
+    enable_if_t<!Dyn, ssize_t> size() const {
+        return std::accumulate(shape_.begin(), shape_.end(), (ssize_t) 1, std::multiplies<ssize_t>());
     }
     template <bool Dyn = Dynamic>
-    enable_if_t<Dyn, size_t> size() const {
-        return std::accumulate(shape_, shape_ + ndim(), (size_t) 1, std::multiplies<size_t>());
+    enable_if_t<Dyn, ssize_t> size() const {
+        return std::accumulate(shape_, shape_ + ndim(), (ssize_t) 1, std::multiplies<ssize_t>());
     }
 
     /// Returns the total number of bytes used by the referenced data.  Note that the actual span in
     /// memory may be larger if the referenced array has non-contiguous strides (e.g. for a slice).
-    size_t nbytes() const {
+    ssize_t nbytes() const {
         return size() * itemsize();
     }
 };
@@ -323,31 +428,36 @@ class unchecked_mutable_reference : public unchecked_reference<T, Dims> {
     using ConstBase::ConstBase;
     using ConstBase::Dynamic;
 public:
+    // Bring in const-qualified versions from base class
+    using ConstBase::operator();
+    using ConstBase::operator[];
+
     /// Mutable, unchecked access to data at the given indices.
     template <typename... Ix> T& operator()(Ix... index) {
-        static_assert(sizeof...(Ix) == Dims || Dynamic,
+        static_assert(ssize_t{sizeof...(Ix)} == Dims || Dynamic,
                 "Invalid number of indices for unchecked array reference");
         return const_cast<T &>(ConstBase::operator()(index...));
     }
-    /** Mutable, unchecked access data at the given index; this operator only participates if the
+    /**
+     * Mutable, unchecked access data at the given index; this operator only participates if the
      * reference is to a 1-dimensional array (or has runtime dimensions).  When present, this is
      * exactly equivalent to `obj(index)`.
      */
-    template <size_t D = Dims, typename = enable_if_t<D == 1 || Dynamic>>
-    T &operator[](size_t index) { return operator()(index); }
+    template <ssize_t D = Dims, typename = enable_if_t<D == 1 || Dynamic>>
+    T &operator[](ssize_t index) { return operator()(index); }
 
     /// Mutable pointer access to the data at the given indices.
-    template <typename... Ix> T *mutable_data(Ix... ix) { return &operator()(size_t(ix)...); }
+    template <typename... Ix> T *mutable_data(Ix... ix) { return &operator()(ssize_t(ix)...); }
 };
 
-template <typename T, size_t Dim>
+template <typename T, ssize_t Dim>
 struct type_caster<unchecked_reference<T, Dim>> {
     static_assert(Dim == 0 && Dim > 0 /* always fail */, "unchecked array proxy object is not castable");
 };
-template <typename T, size_t Dim>
+template <typename T, ssize_t Dim>
 struct type_caster<unchecked_mutable_reference<T, Dim>> : type_caster<unchecked_reference<T, Dim>> {};
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 class dtype : public object {
 public:
@@ -365,7 +475,7 @@ class dtype : public object {
 
     dtype(const char *format) : dtype(std::string(format)) { }
 
-    dtype(list names, list formats, list offsets, size_t itemsize) {
+    dtype(list names, list formats, list offsets, ssize_t itemsize) {
         dict args;
         args["names"] = names;
         args["formats"] = formats;
@@ -377,7 +487,7 @@ class dtype : public object {
     /// This is essentially the same as calling numpy.dtype(args) in Python.
     static dtype from_args(object args) {
         PyObject *ptr = nullptr;
-        if (!detail::npy_api::get().PyArray_DescrConverter_(args.release().ptr(), &ptr) || !ptr)
+        if (!detail::npy_api::get().PyArray_DescrConverter_(args.ptr(), &ptr) || !ptr)
             throw error_already_set();
         return reinterpret_steal<dtype>(ptr);
     }
@@ -388,8 +498,8 @@ class dtype : public object {
     }
 
     /// Size of the data type in bytes.
-    size_t itemsize() const {
-        return (size_t) detail::array_descriptor_proxy(m_ptr)->elsize;
+    ssize_t itemsize() const {
+        return detail::array_descriptor_proxy(m_ptr)->elsize;
     }
 
     /// Returns true for structured data types.
@@ -404,12 +514,12 @@ class dtype : public object {
 
 private:
     static object _dtype_from_pep3118() {
-        static PyObject *obj = module::import("numpy.core._internal")
+        static PyObject *obj = module_::import("numpy.core._internal")
             .attr("_dtype_from_pep3118").cast<object>().release().ptr();
         return reinterpret_borrow<object>(obj);
     }
 
-    dtype strip_padding(size_t itemsize) {
+    dtype strip_padding(ssize_t itemsize) {
         // Recursively strip all void fields with empty names that are generated for
         // padding fields (as of NumPy v1.11).
         if (!has_fields())
@@ -455,12 +565,18 @@ class array : public buffer {
 
     array() : array(0, static_cast<const double *>(nullptr)) {}
 
-    array(const pybind11::dtype &dt, const std::vector<size_t> &shape,
-          const std::vector<size_t> &strides, const void *ptr = nullptr,
-          handle base = handle()) {
-        auto& api = detail::npy_api::get();
-        auto ndim = shape.size();
-        if (shape.size() != strides.size())
+    using ShapeContainer = detail::any_container<ssize_t>;
+    using StridesContainer = detail::any_container<ssize_t>;
+
+    // Constructs an array taking shape/strides from arbitrary container types
+    array(const pybind11::dtype &dt, ShapeContainer shape, StridesContainer strides,
+          const void *ptr = nullptr, handle base = handle()) {
+
+        if (strides->empty())
+            *strides = detail::c_strides(*shape, dt.itemsize());
+
+        auto ndim = shape->size();
+        if (ndim != strides->size())
             pybind11_fail("NumPy: shape ndim doesn't match strides ndim");
         auto descr = dt;
 
@@ -474,13 +590,15 @@ class array : public buffer {
                 flags = detail::npy_api::NPY_ARRAY_WRITEABLE_;
         }
 
+        auto &api = detail::npy_api::get();
         auto tmp = reinterpret_steal<object>(api.PyArray_NewFromDescr_(
             api.PyArray_Type_, descr.release().ptr(), (int) ndim,
-            reinterpret_cast<Py_intptr_t *>(const_cast<size_t*>(shape.data())),
-            reinterpret_cast<Py_intptr_t *>(const_cast<size_t*>(strides.data())),
+            // Use reinterpret_cast for PyPy on Windows (remove if fixed, checked on 7.3.1)
+            reinterpret_cast<Py_intptr_t*>(shape->data()),
+            reinterpret_cast<Py_intptr_t*>(strides->data()),
             const_cast<void *>(ptr), flags, nullptr));
         if (!tmp)
-            pybind11_fail("NumPy: unable to create array!");
+            throw error_already_set();
         if (ptr) {
             if (base) {
                 api.PyArray_SetBaseObject_(tmp.ptr(), base.inc_ref().ptr());
@@ -491,30 +609,26 @@ class array : public buffer {
         m_ptr = tmp.release().ptr();
     }
 
-    array(const pybind11::dtype &dt, const std::vector<size_t> &shape,
-          const void *ptr = nullptr, handle base = handle())
-        : array(dt, shape, default_strides(shape, dt.itemsize()), ptr, base) { }
+    array(const pybind11::dtype &dt, ShapeContainer shape, const void *ptr = nullptr, handle base = handle())
+        : array(dt, std::move(shape), {}, ptr, base) { }
 
-    array(const pybind11::dtype &dt, size_t count, const void *ptr = nullptr,
-          handle base = handle())
-        : array(dt, std::vector<size_t>{ count }, ptr, base) { }
+    template <typename T, typename = detail::enable_if_t<std::is_integral<T>::value && !std::is_same<bool, T>::value>>
+    array(const pybind11::dtype &dt, T count, const void *ptr = nullptr, handle base = handle())
+        : array(dt, {{count}}, ptr, base) { }
 
-    template<typename T> array(const std::vector<size_t>& shape,
-                               const std::vector<size_t>& strides,
-                               const T* ptr, handle base = handle())
-    : array(pybind11::dtype::of<T>(), shape, strides, (const void *) ptr, base) { }
+    template <typename T>
+    array(ShapeContainer shape, StridesContainer strides, const T *ptr, handle base = handle())
+        : array(pybind11::dtype::of<T>(), std::move(shape), std::move(strides), ptr, base) { }
 
     template <typename T>
-    array(const std::vector<size_t> &shape, const T *ptr,
-          handle base = handle())
-        : array(shape, default_strides(shape, sizeof(T)), ptr, base) { }
+    array(ShapeContainer shape, const T *ptr, handle base = handle())
+        : array(std::move(shape), {}, ptr, base) { }
 
     template <typename T>
-    array(size_t count, const T *ptr, handle base = handle())
-        : array(std::vector<size_t>{ count }, ptr, base) { }
+    explicit array(ssize_t count, const T *ptr, handle base = handle()) : array({count}, {}, ptr, base) { }
 
-    explicit array(const buffer_info &info)
-    : array(pybind11::dtype(info), info.shape, info.strides, info.ptr) { }
+    explicit array(const buffer_info &info, handle base = handle())
+    : array(pybind11::dtype(info), info.shape, info.strides, info.ptr, base) { }
 
     /// Array descriptor (dtype)
     pybind11::dtype dtype() const {
@@ -522,23 +636,23 @@ class array : public buffer {
     }
 
     /// Total number of elements
-    size_t size() const {
-        return std::accumulate(shape(), shape() + ndim(), (size_t) 1, std::multiplies<size_t>());
+    ssize_t size() const {
+        return std::accumulate(shape(), shape() + ndim(), (ssize_t) 1, std::multiplies<ssize_t>());
     }
 
     /// Byte size of a single element
-    size_t itemsize() const {
-        return (size_t) detail::array_descriptor_proxy(detail::array_proxy(m_ptr)->descr)->elsize;
+    ssize_t itemsize() const {
+        return detail::array_descriptor_proxy(detail::array_proxy(m_ptr)->descr)->elsize;
     }
 
     /// Total number of bytes
-    size_t nbytes() const {
+    ssize_t nbytes() const {
         return size() * itemsize();
     }
 
     /// Number of dimensions
-    size_t ndim() const {
-        return (size_t) detail::array_proxy(m_ptr)->nd;
+    ssize_t ndim() const {
+        return detail::array_proxy(m_ptr)->nd;
     }
 
     /// Base object
@@ -547,24 +661,24 @@ class array : public buffer {
     }
 
     /// Dimensions of the array
-    const size_t* shape() const {
-        return reinterpret_cast<const size_t *>(detail::array_proxy(m_ptr)->dimensions);
+    const ssize_t* shape() const {
+        return detail::array_proxy(m_ptr)->dimensions;
     }
 
     /// Dimension along a given axis
-    size_t shape(size_t dim) const {
+    ssize_t shape(ssize_t dim) const {
         if (dim >= ndim())
             fail_dim_check(dim, "invalid axis");
         return shape()[dim];
     }
 
     /// Strides of the array
-    const size_t* strides() const {
-        return reinterpret_cast<const size_t *>(detail::array_proxy(m_ptr)->strides);
+    const ssize_t* strides() const {
+        return detail::array_proxy(m_ptr)->strides;
     }
 
     /// Stride along a given axis
-    size_t strides(size_t dim) const {
+    ssize_t strides(ssize_t dim) const {
         if (dim >= ndim())
             fail_dim_check(dim, "invalid axis");
         return strides()[dim];
@@ -601,40 +715,42 @@ class array : public buffer {
 
     /// Byte offset from beginning of the array to a given index (full or partial).
     /// May throw if the index would lead to out of bounds access.
-    template<typename... Ix> size_t offset_at(Ix... index) const {
-        if (sizeof...(index) > ndim())
+    template<typename... Ix> ssize_t offset_at(Ix... index) const {
+        if ((ssize_t) sizeof...(index) > ndim())
             fail_dim_check(sizeof...(index), "too many indices for an array");
-        return byte_offset(size_t(index)...);
+        return byte_offset(ssize_t(index)...);
     }
 
-    size_t offset_at() const { return 0; }
+    ssize_t offset_at() const { return 0; }
 
     /// Item count from beginning of the array to a given index (full or partial).
     /// May throw if the index would lead to out of bounds access.
-    template<typename... Ix> size_t index_at(Ix... index) const {
+    template<typename... Ix> ssize_t index_at(Ix... index) const {
         return offset_at(index...) / itemsize();
     }
 
-    /** Returns a proxy object that provides access to the array's data without bounds or
+    /**
+     * Returns a proxy object that provides access to the array's data without bounds or
      * dimensionality checking.  Will throw if the array is missing the `writeable` flag.  Use with
      * care: the array must not be destroyed or reshaped for the duration of the returned object,
      * and the caller must take care not to access invalid dimensions or dimension indices.
      */
-    template <typename T, ssize_t Dims = -1> detail::unchecked_mutable_reference<T, Dims> mutable_unchecked() {
-        if (Dims >= 0 && ndim() != (size_t) Dims)
+    template <typename T, ssize_t Dims = -1> detail::unchecked_mutable_reference<T, Dims> mutable_unchecked() & {
+        if (Dims >= 0 && ndim() != Dims)
             throw std::domain_error("array has incorrect number of dimensions: " + std::to_string(ndim()) +
                     "; expected " + std::to_string(Dims));
         return detail::unchecked_mutable_reference<T, Dims>(mutable_data(), shape(), strides(), ndim());
     }
 
-    /** Returns a proxy object that provides const access to the array's data without bounds or
+    /**
+     * Returns a proxy object that provides const access to the array's data without bounds or
      * dimensionality checking.  Unlike `mutable_unchecked()`, this does not require that the
      * underlying array have the `writable` flag.  Use with care: the array must not be destroyed or
      * reshaped for the duration of the returned object, and the caller must take care not to access
      * invalid dimensions or dimension indices.
      */
-    template <typename T, ssize_t Dims = -1> detail::unchecked_reference<T, Dims> unchecked() const {
-        if (Dims >= 0 && ndim() != (size_t) Dims)
+    template <typename T, ssize_t Dims = -1> detail::unchecked_reference<T, Dims> unchecked() const & {
+        if (Dims >= 0 && ndim() != Dims)
             throw std::domain_error("array has incorrect number of dimensions: " + std::to_string(ndim()) +
                     "; expected " + std::to_string(Dims));
         return detail::unchecked_reference<T, Dims>(data(), shape(), strides(), ndim());
@@ -646,6 +762,23 @@ class array : public buffer {
         return reinterpret_steal<array>(api.PyArray_Squeeze_(m_ptr));
     }
 
+    /// Resize array to given shape
+    /// If refcheck is true and more that one reference exist to this array
+    /// then resize will succeed only if it makes a reshape, i.e. original size doesn't change
+    void resize(ShapeContainer new_shape, bool refcheck = true) {
+        detail::npy_api::PyArray_Dims d = {
+            // Use reinterpret_cast for PyPy on Windows (remove if fixed, checked on 7.3.1)
+            reinterpret_cast<Py_intptr_t*>(new_shape->data()),
+            int(new_shape->size())
+        };
+        // try to resize, set ordering param to -1 cause it's not used anyway
+        auto new_array = reinterpret_steal<object>(
+            detail::npy_api::get().PyArray_Resize_(m_ptr, &d, int(refcheck), -1)
+        );
+        if (!new_array) throw error_already_set();
+        if (isinstance<array>(new_array)) { *this = std::move(new_array); }
+    }
+
     /// Ensure that the argument is a NumPy array
     /// In case of an error, nullptr is returned and the Python error is cleared.
     static array ensure(handle h, int ExtraFlags = 0) {
@@ -658,14 +791,14 @@ class array : public buffer {
 protected:
     template<typename, typename> friend struct detail::npy_format_descriptor;
 
-    void fail_dim_check(size_t dim, const std::string& msg) const {
+    void fail_dim_check(ssize_t dim, const std::string& msg) const {
         throw index_error(msg + ": " + std::to_string(dim) +
                           " (ndim = " + std::to_string(ndim()) + ")");
     }
 
-    template<typename... Ix> size_t byte_offset(Ix... index) const {
+    template<typename... Ix> ssize_t byte_offset(Ix... index) const {
         check_dimensions(index...);
-        return detail::byte_offset_unsafe(strides(), size_t(index)...);
+        return detail::byte_offset_unsafe(strides(), ssize_t(index)...);
     }
 
     void check_writeable() const {
@@ -673,25 +806,13 @@ class array : public buffer {
             throw std::domain_error("array is not writeable");
     }
 
-    static std::vector<size_t> default_strides(const std::vector<size_t>& shape, size_t itemsize) {
-        auto ndim = shape.size();
-        std::vector<size_t> strides(ndim);
-        if (ndim) {
-            std::fill(strides.begin(), strides.end(), itemsize);
-            for (size_t i = 0; i < ndim - 1; i++)
-                for (size_t j = 0; j < ndim - 1 - i; j++)
-                    strides[j] *= shape[ndim - 1 - i];
-        }
-        return strides;
-    }
-
     template<typename... Ix> void check_dimensions(Ix... index) const {
-        check_dimensions_impl(size_t(0), shape(), size_t(index)...);
+        check_dimensions_impl(ssize_t(0), shape(), ssize_t(index)...);
     }
 
-    void check_dimensions_impl(size_t, const size_t*) const { }
+    void check_dimensions_impl(ssize_t, const ssize_t*) const { }
 
-    template<typename... Ix> void check_dimensions_impl(size_t axis, const size_t* shape, size_t i, Ix... index) const {
+    template<typename... Ix> void check_dimensions_impl(ssize_t axis, const ssize_t* shape, ssize_t i, Ix... index) const {
         if (i >= *shape) {
             throw index_error(std::string("index ") + std::to_string(i) +
                               " is out of bounds for axis " + std::to_string(axis) +
@@ -702,50 +823,60 @@ class array : public buffer {
 
     /// Create array from any object -- always returns a new reference
     static PyObject *raw_array(PyObject *ptr, int ExtraFlags = 0) {
-        if (ptr == nullptr)
+        if (ptr == nullptr) {
+            PyErr_SetString(PyExc_ValueError, "cannot create a pybind11::array from a nullptr");
             return nullptr;
+        }
         return detail::npy_api::get().PyArray_FromAny_(
             ptr, nullptr, 0, 0, detail::npy_api::NPY_ARRAY_ENSUREARRAY_ | ExtraFlags, nullptr);
     }
 };
 
 template <typename T, int ExtraFlags = array::forcecast> class array_t : public array {
+private:
+    struct private_ctor {};
+    // Delegating constructor needed when both moving and accessing in the same constructor
+    array_t(private_ctor, ShapeContainer &&shape, StridesContainer &&strides, const T *ptr, handle base)
+        : array(std::move(shape), std::move(strides), ptr, base) {}
 public:
+    static_assert(!detail::array_info<T>::is_array, "Array types cannot be used with array_t");
+
     using value_type = T;
 
     array_t() : array(0, static_cast<const T *>(nullptr)) {}
-    array_t(handle h, borrowed_t) : array(h, borrowed) { }
-    array_t(handle h, stolen_t) : array(h, stolen) { }
+    array_t(handle h, borrowed_t) : array(h, borrowed_t{}) { }
+    array_t(handle h, stolen_t) : array(h, stolen_t{}) { }
 
     PYBIND11_DEPRECATED("Use array_t<T>::ensure() instead")
-    array_t(handle h, bool is_borrowed) : array(raw_array_t(h.ptr()), stolen) {
+    array_t(handle h, bool is_borrowed) : array(raw_array_t(h.ptr()), stolen_t{}) {
         if (!m_ptr) PyErr_Clear();
         if (!is_borrowed) Py_XDECREF(h.ptr());
     }
 
-    array_t(const object &o) : array(raw_array_t(o.ptr()), stolen) {
+    array_t(const object &o) : array(raw_array_t(o.ptr()), stolen_t{}) {
         if (!m_ptr) throw error_already_set();
     }
 
-    explicit array_t(const buffer_info& info) : array(info) { }
+    explicit array_t(const buffer_info& info, handle base = handle()) : array(info, base) { }
 
-    array_t(const std::vector<size_t> &shape,
-            const std::vector<size_t> &strides, const T *ptr = nullptr,
-            handle base = handle())
-        : array(shape, strides, ptr, base) { }
+    array_t(ShapeContainer shape, StridesContainer strides, const T *ptr = nullptr, handle base = handle())
+        : array(std::move(shape), std::move(strides), ptr, base) { }
 
-    explicit array_t(const std::vector<size_t> &shape, const T *ptr = nullptr,
-            handle base = handle())
-        : array(shape, ptr, base) { }
+    explicit array_t(ShapeContainer shape, const T *ptr = nullptr, handle base = handle())
+        : array_t(private_ctor{}, std::move(shape),
+                ExtraFlags & f_style
+                ? detail::f_strides(*shape, itemsize())
+                : detail::c_strides(*shape, itemsize()),
+                ptr, base) { }
 
-    explicit array_t(size_t count, const T *ptr = nullptr, handle base = handle())
-        : array(count, ptr, base) { }
+    explicit array_t(ssize_t count, const T *ptr = nullptr, handle base = handle())
+        : array({count}, {}, ptr, base) { }
 
-    constexpr size_t itemsize() const {
+    constexpr ssize_t itemsize() const {
         return sizeof(T);
     }
 
-    template<typename... Ix> size_t index_at(Ix... index) const {
+    template<typename... Ix> ssize_t index_at(Ix... index) const {
         return offset_at(index...) / itemsize();
     }
 
@@ -759,34 +890,36 @@ template <typename T, int ExtraFlags = array::forcecast> class array_t : public
 
     // Reference to element at a given index
     template<typename... Ix> const T& at(Ix... index) const {
-        if (sizeof...(index) != ndim())
+        if ((ssize_t) sizeof...(index) != ndim())
             fail_dim_check(sizeof...(index), "index dimension mismatch");
-        return *(static_cast<const T*>(array::data()) + byte_offset(size_t(index)...) / itemsize());
+        return *(static_cast<const T*>(array::data()) + byte_offset(ssize_t(index)...) / itemsize());
     }
 
     // Mutable reference to element at a given index
     template<typename... Ix> T& mutable_at(Ix... index) {
-        if (sizeof...(index) != ndim())
+        if ((ssize_t) sizeof...(index) != ndim())
             fail_dim_check(sizeof...(index), "index dimension mismatch");
-        return *(static_cast<T*>(array::mutable_data()) + byte_offset(size_t(index)...) / itemsize());
+        return *(static_cast<T*>(array::mutable_data()) + byte_offset(ssize_t(index)...) / itemsize());
     }
 
-    /** Returns a proxy object that provides access to the array's data without bounds or
+    /**
+     * Returns a proxy object that provides access to the array's data without bounds or
      * dimensionality checking.  Will throw if the array is missing the `writeable` flag.  Use with
      * care: the array must not be destroyed or reshaped for the duration of the returned object,
      * and the caller must take care not to access invalid dimensions or dimension indices.
      */
-    template <ssize_t Dims = -1> detail::unchecked_mutable_reference<T, Dims> mutable_unchecked() {
+    template <ssize_t Dims = -1> detail::unchecked_mutable_reference<T, Dims> mutable_unchecked() & {
         return array::mutable_unchecked<T, Dims>();
     }
 
-    /** Returns a proxy object that provides const access to the array's data without bounds or
+    /**
+     * Returns a proxy object that provides const access to the array's data without bounds or
      * dimensionality checking.  Unlike `unchecked()`, this does not require that the underlying
      * array have the `writable` flag.  Use with care: the array must not be destroyed or reshaped
      * for the duration of the returned object, and the caller must take care not to access invalid
      * dimensions or dimension indices.
      */
-    template <ssize_t Dims = -1> detail::unchecked_reference<T, Dims> unchecked() const {
+    template <ssize_t Dims = -1> detail::unchecked_reference<T, Dims> unchecked() const & {
         return array::unchecked<T, Dims>();
     }
 
@@ -802,14 +935,17 @@ template <typename T, int ExtraFlags = array::forcecast> class array_t : public
     static bool check_(handle h) {
         const auto &api = detail::npy_api::get();
         return api.PyArray_Check_(h.ptr())
-               && api.PyArray_EquivTypes_(detail::array_proxy(h.ptr())->descr, dtype::of<T>().ptr());
+               && api.PyArray_EquivTypes_(detail::array_proxy(h.ptr())->descr, dtype::of<T>().ptr())
+               && detail::check_flags(h.ptr(), ExtraFlags & (array::c_style | array::f_style));
     }
 
 protected:
     /// Create array from any object -- always returns a new reference
     static PyObject *raw_array_t(PyObject *ptr) {
-        if (ptr == nullptr)
+        if (ptr == nullptr) {
+            PyErr_SetString(PyExc_ValueError, "cannot create a pybind11::array_t from a nullptr");
             return nullptr;
+        }
         return detail::npy_api::get().PyArray_FromAny_(
             ptr, dtype::of<T>().release().ptr(), 0, 0,
             detail::npy_api::NPY_ARRAY_ENSUREARRAY_ | ExtraFlags, nullptr);
@@ -838,7 +974,16 @@ struct format_descriptor<T, detail::enable_if_t<std::is_enum<T>::value>> {
     }
 };
 
-NAMESPACE_BEGIN(detail)
+template <typename T>
+struct format_descriptor<T, detail::enable_if_t<detail::array_info<T>::is_array>> {
+    static std::string format() {
+        using namespace detail;
+        static constexpr auto extents = _("(") + array_info<T>::extents + _(")");
+        return extents.text + format_descriptor<remove_all_extents_t<T>>::format();
+    }
+};
+
+PYBIND11_NAMESPACE_BEGIN(detail)
 template <typename T, int ExtraFlags>
 struct pyobject_caster<array_t<T, ExtraFlags>> {
     using type = array_t<T, ExtraFlags>;
@@ -853,7 +998,7 @@ struct pyobject_caster<array_t<T, ExtraFlags>> {
     static handle cast(const handle &src, return_value_policy /* policy */, handle /* parent */) {
         return src.inc_ref();
     }
-    PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name());
+    PYBIND11_TYPE_CASTER(type, handle_type_name<type>::name);
 };
 
 template <typename T>
@@ -863,13 +1008,40 @@ struct compare_buffer_info<T, detail::enable_if_t<detail::is_pod_struct<T>::valu
     }
 };
 
-template <typename T> struct npy_format_descriptor<T, enable_if_t<satisfies_any_of<T, std::is_arithmetic, is_complex>::value>> {
+template <typename T, typename = void>
+struct npy_format_descriptor_name;
+
+template <typename T>
+struct npy_format_descriptor_name<T, enable_if_t<std::is_integral<T>::value>> {
+    static constexpr auto name = _<std::is_same<T, bool>::value>(
+        _("bool"), _<std::is_signed<T>::value>("numpy.int", "numpy.uint") + _<sizeof(T)*8>()
+    );
+};
+
+template <typename T>
+struct npy_format_descriptor_name<T, enable_if_t<std::is_floating_point<T>::value>> {
+    static constexpr auto name = _<std::is_same<T, float>::value || std::is_same<T, double>::value>(
+        _("numpy.float") + _<sizeof(T)*8>(), _("numpy.longdouble")
+    );
+};
+
+template <typename T>
+struct npy_format_descriptor_name<T, enable_if_t<is_complex<T>::value>> {
+    static constexpr auto name = _<std::is_same<typename T::value_type, float>::value
+                                   || std::is_same<typename T::value_type, double>::value>(
+        _("numpy.complex") + _<sizeof(typename T::value_type)*16>(), _("numpy.longcomplex")
+    );
+};
+
+template <typename T>
+struct npy_format_descriptor<T, enable_if_t<satisfies_any_of<T, std::is_arithmetic, is_complex>::value>>
+    : npy_format_descriptor_name<T> {
 private:
     // NB: the order here must match the one in common.h
     constexpr static const int values[15] = {
         npy_api::NPY_BOOL_,
-        npy_api::NPY_BYTE_,   npy_api::NPY_UBYTE_,   npy_api::NPY_SHORT_,    npy_api::NPY_USHORT_,
-        npy_api::NPY_INT_,    npy_api::NPY_UINT_,    npy_api::NPY_LONGLONG_, npy_api::NPY_ULONGLONG_,
+        npy_api::NPY_BYTE_,   npy_api::NPY_UBYTE_,   npy_api::NPY_INT16_,    npy_api::NPY_UINT16_,
+        npy_api::NPY_INT32_,  npy_api::NPY_UINT32_,  npy_api::NPY_INT64_,    npy_api::NPY_UINT64_,
         npy_api::NPY_FLOAT_,  npy_api::NPY_DOUBLE_,  npy_api::NPY_LONGDOUBLE_,
         npy_api::NPY_CFLOAT_, npy_api::NPY_CDOUBLE_, npy_api::NPY_CLONGDOUBLE_
     };
@@ -879,61 +1051,65 @@ template <typename T> struct npy_format_descriptor<T, enable_if_t<satisfies_any_
 
     static pybind11::dtype dtype() {
         if (auto ptr = npy_api::get().PyArray_DescrFromType_(value))
-            return reinterpret_borrow<pybind11::dtype>(ptr);
+            return reinterpret_steal<pybind11::dtype>(ptr);
         pybind11_fail("Unsupported buffer format!");
     }
-    template <typename T2 = T, enable_if_t<std::is_integral<T2>::value, int> = 0>
-    static PYBIND11_DESCR name() {
-        return _<std::is_same<T, bool>::value>(_("bool"),
-            _<std::is_signed<T>::value>("int", "uint") + _<sizeof(T)*8>());
-    }
-    template <typename T2 = T, enable_if_t<std::is_floating_point<T2>::value, int> = 0>
-    static PYBIND11_DESCR name() {
-        return _<std::is_same<T, float>::value || std::is_same<T, double>::value>(
-                _("float") + _<sizeof(T)*8>(), _("longdouble"));
-    }
-    template <typename T2 = T, enable_if_t<is_complex<T2>::value, int> = 0>
-    static PYBIND11_DESCR name() {
-        return _<std::is_same<typename T2::value_type, float>::value || std::is_same<typename T2::value_type, double>::value>(
-                _("complex") + _<sizeof(typename T2::value_type)*16>(), _("longcomplex"));
-    }
 };
 
 #define PYBIND11_DECL_CHAR_FMT \
-    static PYBIND11_DESCR name() { return _("S") + _<N>(); } \
+    static constexpr auto name = _("S") + _<N>(); \
     static pybind11::dtype dtype() { return pybind11::dtype(std::string("S") + std::to_string(N)); }
 template <size_t N> struct npy_format_descriptor<char[N]> { PYBIND11_DECL_CHAR_FMT };
 template <size_t N> struct npy_format_descriptor<std::array<char, N>> { PYBIND11_DECL_CHAR_FMT };
 #undef PYBIND11_DECL_CHAR_FMT
 
+template<typename T> struct npy_format_descriptor<T, enable_if_t<array_info<T>::is_array>> {
+private:
+    using base_descr = npy_format_descriptor<typename array_info<T>::type>;
+public:
+    static_assert(!array_info<T>::is_empty, "Zero-sized arrays are not supported");
+
+    static constexpr auto name = _("(") + array_info<T>::extents + _(")") + base_descr::name;
+    static pybind11::dtype dtype() {
+        list shape;
+        array_info<T>::append_extents(shape);
+        return pybind11::dtype::from_args(pybind11::make_tuple(base_descr::dtype(), shape));
+    }
+};
+
 template<typename T> struct npy_format_descriptor<T, enable_if_t<std::is_enum<T>::value>> {
 private:
     using base_descr = npy_format_descriptor<typename std::underlying_type<T>::type>;
 public:
-    static PYBIND11_DESCR name() { return base_descr::name(); }
+    static constexpr auto name = base_descr::name;
     static pybind11::dtype dtype() { return base_descr::dtype(); }
 };
 
 struct field_descriptor {
     const char *name;
-    size_t offset;
-    size_t size;
-    size_t alignment;
+    ssize_t offset;
+    ssize_t size;
     std::string format;
     dtype descr;
 };
 
 inline PYBIND11_NOINLINE void register_structured_dtype(
-    const std::initializer_list<field_descriptor>& fields,
-    const std::type_info& tinfo, size_t itemsize,
+    any_container<field_descriptor> fields,
+    const std::type_info& tinfo, ssize_t itemsize,
     bool (*direct_converter)(PyObject *, void *&)) {
 
     auto& numpy_internals = get_numpy_internals();
     if (numpy_internals.get_type_info(tinfo, false))
         pybind11_fail("NumPy: dtype is already registered");
 
+    // Use ordered fields because order matters as of NumPy 1.14:
+    // https://docs.scipy.org/doc/numpy/release.html#multiple-field-indexing-assignment-of-structured-arrays
+    std::vector<field_descriptor> ordered_fields(std::move(fields));
+    std::sort(ordered_fields.begin(), ordered_fields.end(),
+        [](const field_descriptor &a, const field_descriptor &b) { return a.offset < b.offset; });
+
     list names, formats, offsets;
-    for (auto field : fields) {
+    for (auto& field : ordered_fields) {
         if (!field.descr)
             pybind11_fail(std::string("NumPy: unsupported field dtype: `") +
                             field.name + "` @ " + tinfo.name());
@@ -950,18 +1126,17 @@ inline PYBIND11_NOINLINE void register_structured_dtype(
     // - https://github.com/numpy/numpy/pull/7798
     // Because of this, we won't use numpy's logic to generate buffer format
     // strings and will just do it ourselves.
-    std::vector<field_descriptor> ordered_fields(fields);
-    std::sort(ordered_fields.begin(), ordered_fields.end(),
-        [](const field_descriptor &a, const field_descriptor &b) { return a.offset < b.offset; });
-    size_t offset = 0;
+    ssize_t offset = 0;
     std::ostringstream oss;
-    oss << "T{";
+    // mark the structure as unaligned with '^', because numpy and C++ don't
+    // always agree about alignment (particularly for complex), and we're
+    // explicitly listing all our padding. This depends on none of the fields
+    // overriding the endianness. Putting the ^ in front of individual fields
+    // isn't guaranteed to work due to https://github.com/numpy/numpy/issues/9049
+    oss << "^T{";
     for (auto& field : ordered_fields) {
         if (field.offset > offset)
             oss << (field.offset - offset) << 'x';
-        // mark unaligned fields with '^' (unaligned native type)
-        if (field.offset % field.alignment)
-            oss << '^';
         oss << field.format << ':' << field.name << ':';
         offset = field.offset + field.size;
     }
@@ -984,7 +1159,7 @@ inline PYBIND11_NOINLINE void register_structured_dtype(
 template <typename T, typename SFINAE> struct npy_format_descriptor {
     static_assert(is_pod_struct<T>::value, "Attempt to use a non-POD or unimplemented POD type as a numpy dtype");
 
-    static PYBIND11_DESCR name() { return make_caster<T>::name(); }
+    static constexpr auto name = make_caster<T>::name;
 
     static pybind11::dtype dtype() {
         return reinterpret_borrow<pybind11::dtype>(dtype_ptr());
@@ -995,8 +1170,8 @@ template <typename T, typename SFINAE> struct npy_format_descriptor {
         return format_str;
     }
 
-    static void register_dtype(const std::initializer_list<field_descriptor>& fields) {
-        register_structured_dtype(fields, typeid(typename std::remove_cv<T>::type),
+    static void register_dtype(any_container<field_descriptor> fields) {
+        register_structured_dtype(std::move(fields), typeid(typename std::remove_cv<T>::type),
                                   sizeof(T), &direct_converter);
     }
 
@@ -1020,10 +1195,14 @@ template <typename T, typename SFINAE> struct npy_format_descriptor {
     }
 };
 
+#ifdef __CLION_IDE__ // replace heavy macro with dummy code for the IDE (doesn't affect code)
+# define PYBIND11_NUMPY_DTYPE(Type, ...) ((void)0)
+# define PYBIND11_NUMPY_DTYPE_EX(Type, ...) ((void)0)
+#else
+
 #define PYBIND11_FIELD_DESCRIPTOR_EX(T, Field, Name)                                          \
     ::pybind11::detail::field_descriptor {                                                    \
         Name, offsetof(T, Field), sizeof(decltype(std::declval<T>().Field)),                  \
-        alignof(decltype(std::declval<T>().Field)),                                           \
         ::pybind11::format_descriptor<decltype(std::declval<T>().Field)>::format(),           \
         ::pybind11::detail::npy_format_descriptor<decltype(std::declval<T>().Field)>::dtype() \
     }
@@ -1046,7 +1225,7 @@ template <typename T, typename SFINAE> struct npy_format_descriptor {
 #define PYBIND11_MAP_NEXT0(test, next, ...) next PYBIND11_MAP_OUT
 #define PYBIND11_MAP_NEXT1(test, next) PYBIND11_MAP_NEXT0 (test, next, 0)
 #define PYBIND11_MAP_NEXT(test, next)  PYBIND11_MAP_NEXT1 (PYBIND11_MAP_GET_END test, next)
-#ifdef _MSC_VER // MSVC is not as eager to expand macros, hence this workaround
+#if defined(_MSC_VER) && !defined(__clang__) // MSVC is not as eager to expand macros, hence this workaround
 #define PYBIND11_MAP_LIST_NEXT1(test, next) \
     PYBIND11_EVAL0 (PYBIND11_MAP_NEXT0 (test, PYBIND11_MAP_COMMA next, 0))
 #else
@@ -1065,9 +1244,10 @@ template <typename T, typename SFINAE> struct npy_format_descriptor {
 
 #define PYBIND11_NUMPY_DTYPE(Type, ...) \
     ::pybind11::detail::npy_format_descriptor<Type>::register_dtype \
-        ({PYBIND11_MAP_LIST (PYBIND11_FIELD_DESCRIPTOR, Type, __VA_ARGS__)})
+        (::std::vector<::pybind11::detail::field_descriptor> \
+         {PYBIND11_MAP_LIST (PYBIND11_FIELD_DESCRIPTOR, Type, __VA_ARGS__)})
 
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
 #define PYBIND11_MAP2_LIST_NEXT1(test, next) \
     PYBIND11_EVAL0 (PYBIND11_MAP_NEXT0 (test, PYBIND11_MAP_COMMA next, 0))
 #else
@@ -1086,35 +1266,25 @@ template <typename T, typename SFINAE> struct npy_format_descriptor {
 
 #define PYBIND11_NUMPY_DTYPE_EX(Type, ...) \
     ::pybind11::detail::npy_format_descriptor<Type>::register_dtype \
-        ({PYBIND11_MAP2_LIST (PYBIND11_FIELD_DESCRIPTOR_EX, Type, __VA_ARGS__)})
+        (::std::vector<::pybind11::detail::field_descriptor> \
+         {PYBIND11_MAP2_LIST (PYBIND11_FIELD_DESCRIPTOR_EX, Type, __VA_ARGS__)})
 
-template  <class T>
-using array_iterator = typename std::add_pointer<T>::type;
-
-template <class T>
-array_iterator<T> array_begin(const buffer_info& buffer) {
-    return array_iterator<T>(reinterpret_cast<T*>(buffer.ptr));
-}
-
-template <class T>
-array_iterator<T> array_end(const buffer_info& buffer) {
-    return array_iterator<T>(reinterpret_cast<T*>(buffer.ptr) + buffer.size);
-}
+#endif // __CLION_IDE__
 
 class common_iterator {
 public:
-    using container_type = std::vector<size_t>;
+    using container_type = std::vector<ssize_t>;
     using value_type = container_type::value_type;
     using size_type = container_type::size_type;
 
     common_iterator() : p_ptr(0), m_strides() {}
 
-    common_iterator(void* ptr, const container_type& strides, const std::vector<size_t>& shape)
+    common_iterator(void* ptr, const container_type& strides, const container_type& shape)
         : p_ptr(reinterpret_cast<char*>(ptr)), m_strides(strides.size()) {
         m_strides.back() = static_cast<value_type>(strides.back());
         for (size_type i = m_strides.size() - 1; i != 0; --i) {
             size_type j = i - 1;
-            value_type s = static_cast<value_type>(shape[i]);
+            auto s = static_cast<value_type>(shape[i]);
             m_strides[j] = strides[j] + m_strides[i] - strides[i] * s;
         }
     }
@@ -1134,16 +1304,16 @@ class common_iterator {
 
 template <size_t N> class multi_array_iterator {
 public:
-    using container_type = std::vector<size_t>;
+    using container_type = std::vector<ssize_t>;
 
     multi_array_iterator(const std::array<buffer_info, N> &buffers,
-                         const std::vector<size_t> &shape)
+                         const container_type &shape)
         : m_shape(shape.size()), m_index(shape.size(), 0),
           m_common_iterator() {
 
         // Manual copy to avoid conversion warning if using std::copy
         for (size_t i = 0; i < shape.size(); ++i)
-            m_shape[i] = static_cast<container_type::value_type>(shape[i]);
+            m_shape[i] = shape[i];
 
         container_type strides(shape.size());
         for (size_t i = 0; i < N; ++i)
@@ -1163,8 +1333,8 @@ template <size_t N> class multi_array_iterator {
         return *this;
     }
 
-    template <size_t K, class T> const T& data() const {
-        return *reinterpret_cast<T*>(m_common_iterator[K].data());
+    template <size_t K, class T = void> T* data() const {
+        return reinterpret_cast<T*>(m_common_iterator[K].data());
     }
 
 private:
@@ -1172,8 +1342,9 @@ template <size_t N> class multi_array_iterator {
     using common_iter = common_iterator;
 
     void init_common_iterator(const buffer_info &buffer,
-                              const std::vector<size_t> &shape,
-                              common_iter &iterator, container_type &strides) {
+                              const container_type &shape,
+                              common_iter &iterator,
+                              container_type &strides) {
         auto buffer_shape_iter = buffer.shape.rbegin();
         auto buffer_strides_iter = buffer.strides.rbegin();
         auto shape_iter = shape.rbegin();
@@ -1181,7 +1352,7 @@ template <size_t N> class multi_array_iterator {
 
         while (buffer_shape_iter != buffer.shape.rend()) {
             if (*shape_iter == *buffer_shape_iter)
-                *strides_iter = static_cast<size_t>(*buffer_strides_iter);
+                *strides_iter = *buffer_strides_iter;
             else
                 *strides_iter = 0;
 
@@ -1212,13 +1383,13 @@ enum class broadcast_trivial { non_trivial, c_trivial, f_trivial };
 // singleton or a full-size, C-contiguous (`c_trivial`) or Fortran-contiguous (`f_trivial`) storage
 // buffer; returns `non_trivial` otherwise.
 template <size_t N>
-broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, size_t &ndim, std::vector<size_t> &shape) {
-    ndim = std::accumulate(buffers.begin(), buffers.end(), size_t(0), [](size_t res, const buffer_info& buf) {
+broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, ssize_t &ndim, std::vector<ssize_t> &shape) {
+    ndim = std::accumulate(buffers.begin(), buffers.end(), ssize_t(0), [](ssize_t res, const buffer_info &buf) {
         return std::max(res, buf.ndim);
     });
 
     shape.clear();
-    shape.resize(ndim, 1);
+    shape.resize((size_t) ndim, 1);
 
     // Figure out the output size, and make sure all input arrays conform (i.e. are either size 1 or
     // the full size).
@@ -1253,7 +1424,7 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, size_t &n
 
         // Check for C contiguity (but only if previous inputs were also C contiguous)
         if (trivial_broadcast_c) {
-            size_t expect_stride = buffers[i].itemsize;
+            ssize_t expect_stride = buffers[i].itemsize;
             auto end = buffers[i].shape.crend();
             for (auto shape_iter = buffers[i].shape.crbegin(), stride_iter = buffers[i].strides.crbegin();
                     trivial_broadcast_c && shape_iter != end; ++shape_iter, ++stride_iter) {
@@ -1266,7 +1437,7 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, size_t &n
 
         // Check for Fortran contiguity (if previous inputs were also F contiguous)
         if (trivial_broadcast_f) {
-            size_t expect_stride = buffers[i].itemsize;
+            ssize_t expect_stride = buffers[i].itemsize;
             auto end = buffers[i].shape.cend();
             for (auto shape_iter = buffers[i].shape.cbegin(), stride_iter = buffers[i].strides.cbegin();
                     trivial_broadcast_f && shape_iter != end; ++shape_iter, ++stride_iter) {
@@ -1284,109 +1455,238 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, size_t &n
         broadcast_trivial::non_trivial;
 }
 
+template <typename T>
+struct vectorize_arg {
+    static_assert(!std::is_rvalue_reference<T>::value, "Functions with rvalue reference arguments cannot be vectorized");
+    // The wrapped function gets called with this type:
+    using call_type = remove_reference_t<T>;
+    // Is this a vectorized argument?
+    static constexpr bool vectorize =
+        satisfies_any_of<call_type, std::is_arithmetic, is_complex, is_pod>::value &&
+        satisfies_none_of<call_type, std::is_pointer, std::is_array, is_std_array, std::is_enum>::value &&
+        (!std::is_reference<T>::value ||
+         (std::is_lvalue_reference<T>::value && std::is_const<call_type>::value));
+    // Accept this type: an array for vectorized types, otherwise the type as-is:
+    using type = conditional_t<vectorize, array_t<remove_cv_t<call_type>, array::forcecast>, T>;
+};
+
+
+// py::vectorize when a return type is present
+template <typename Func, typename Return, typename... Args>
+struct vectorize_returned_array {
+    using Type = array_t<Return>;
+
+    static Type create(broadcast_trivial trivial, const std::vector<ssize_t> &shape) {
+        if (trivial == broadcast_trivial::f_trivial)
+            return array_t<Return, array::f_style>(shape);
+        else
+            return array_t<Return>(shape);
+    }
+
+    static Return *mutable_data(Type &array) {
+        return array.mutable_data();
+    }
+
+    static Return call(Func &f, Args &... args) {
+        return f(args...);
+    }
+
+    static void call(Return *out, size_t i, Func &f, Args &... args) {
+        out[i] = f(args...);
+    }
+};
+
+// py::vectorize when a return type is not present
+template <typename Func, typename... Args>
+struct vectorize_returned_array<Func, void, Args...> {
+    using Type = none;
+
+    static Type create(broadcast_trivial, const std::vector<ssize_t> &) {
+        return none();
+    }
+
+    static void *mutable_data(Type &) {
+        return nullptr;
+    }
+
+    static detail::void_type call(Func &f, Args &... args) {
+        f(args...);
+        return {};
+    }
+
+    static void call(void *, size_t, Func &f, Args &... args) {
+        f(args...);
+    }
+};
+
+
 template <typename Func, typename Return, typename... Args>
 struct vectorize_helper {
-    typename std::remove_reference<Func>::type f;
+
+// NVCC for some reason breaks if NVectorized is private
+#ifdef __CUDACC__
+public:
+#else
+private:
+#endif
+
     static constexpr size_t N = sizeof...(Args);
+    static constexpr size_t NVectorized = constexpr_sum(vectorize_arg<Args>::vectorize...);
+    static_assert(NVectorized >= 1,
+            "pybind11::vectorize(...) requires a function with at least one vectorizable argument");
 
+public:
     template <typename T>
-    explicit vectorize_helper(T&&f) : f(std::forward<T>(f)) { }
+    explicit vectorize_helper(T &&f) : f(std::forward<T>(f)) { }
 
-    object operator()(array_t<Args, array::forcecast>... args) {
-        return run(args..., make_index_sequence<N>());
+    object operator()(typename vectorize_arg<Args>::type... args) {
+        return run(args...,
+                   make_index_sequence<N>(),
+                   select_indices<vectorize_arg<Args>::vectorize...>(),
+                   make_index_sequence<NVectorized>());
     }
 
-    template <size_t ... Index> object run(array_t<Args, array::forcecast>&... args, index_sequence<Index...> index) {
-        /* Request buffers from all parameters */
-        std::array<buffer_info, N> buffers {{ args.request()... }};
+private:
+    remove_reference_t<Func> f;
+
+    // Internal compiler error in MSVC 19.16.27025.1 (Visual Studio 2017 15.9.4), when compiling with "/permissive-" flag
+    // when arg_call_types is manually inlined.
+    using arg_call_types = std::tuple<typename vectorize_arg<Args>::call_type...>;
+    template <size_t Index> using param_n_t = typename std::tuple_element<Index, arg_call_types>::type;
+
+    using returned_array = vectorize_returned_array<Func, Return, Args...>;
+
+    // Runs a vectorized function given arguments tuple and three index sequences:
+    //     - Index is the full set of 0 ... (N-1) argument indices;
+    //     - VIndex is the subset of argument indices with vectorized parameters, letting us access
+    //       vectorized arguments (anything not in this sequence is passed through)
+    //     - BIndex is a incremental sequence (beginning at 0) of the same size as VIndex, so that
+    //       we can store vectorized buffer_infos in an array (argument VIndex has its buffer at
+    //       index BIndex in the array).
+    template <size_t... Index, size_t... VIndex, size_t... BIndex> object run(
+            typename vectorize_arg<Args>::type &...args,
+            index_sequence<Index...> i_seq, index_sequence<VIndex...> vi_seq, index_sequence<BIndex...> bi_seq) {
+
+        // Pointers to values the function was called with; the vectorized ones set here will start
+        // out as array_t<T> pointers, but they will be changed them to T pointers before we make
+        // call the wrapped function.  Non-vectorized pointers are left as-is.
+        std::array<void *, N> params{{ &args... }};
+
+        // The array of `buffer_info`s of vectorized arguments:
+        std::array<buffer_info, NVectorized> buffers{{ reinterpret_cast<array *>(params[VIndex])->request()... }};
 
         /* Determine dimensions parameters of output array */
-        size_t ndim = 0;
-        std::vector<size_t> shape(0);
-        auto trivial = broadcast(buffers, ndim, shape);
-
-        size_t size = 1;
-        std::vector<size_t> strides(ndim);
-        if (ndim > 0) {
-            if (trivial == broadcast_trivial::f_trivial) {
-                strides[0] = sizeof(Return);
-                for (size_t i = 1; i < ndim; ++i) {
-                    strides[i] = strides[i - 1] * shape[i - 1];
-                    size *= shape[i - 1];
-                }
-                size *= shape[ndim - 1];
-            }
-            else {
-                strides[ndim-1] = sizeof(Return);
-                for (size_t i = ndim - 1; i > 0; --i) {
-                    strides[i - 1] = strides[i] * shape[i];
-                    size *= shape[i];
-                }
-                size *= shape[0];
-            }
+        ssize_t nd = 0;
+        std::vector<ssize_t> shape(0);
+        auto trivial = broadcast(buffers, nd, shape);
+        auto ndim = (size_t) nd;
+
+        size_t size = std::accumulate(shape.begin(), shape.end(), (size_t) 1, std::multiplies<size_t>());
+
+        // If all arguments are 0-dimension arrays (i.e. single values) return a plain value (i.e.
+        // not wrapped in an array).
+        if (size == 1 && ndim == 0) {
+            PYBIND11_EXPAND_SIDE_EFFECTS(params[VIndex] = buffers[BIndex].ptr);
+            return cast(returned_array::call(f, *reinterpret_cast<param_n_t<Index> *>(params[Index])...));
         }
 
-        if (size == 1)
-            return cast(f(*reinterpret_cast<Args *>(buffers[Index].ptr)...));
+        auto result = returned_array::create(trivial, shape);
 
-        array_t<Return> result(shape, strides);
-        auto buf = result.request();
-        auto output = (Return *) buf.ptr;
+        if (size == 0) return std::move(result);
 
         /* Call the function */
-        if (trivial == broadcast_trivial::non_trivial) {
-            apply_broadcast<Index...>(buffers, buf, index);
-        } else {
-            for (size_t i = 0; i < size; ++i)
-                output[i] = f((reinterpret_cast<Args *>(buffers[Index].ptr)[buffers[Index].size == 1 ? 0 : i])...);
+        auto mutable_data = returned_array::mutable_data(result);
+        if (trivial == broadcast_trivial::non_trivial)
+            apply_broadcast(buffers, params, mutable_data, size, shape, i_seq, vi_seq, bi_seq);
+        else
+            apply_trivial(buffers, params, mutable_data, size, i_seq, vi_seq, bi_seq);
+
+        return std::move(result);
+    }
+
+    template <size_t... Index, size_t... VIndex, size_t... BIndex>
+    void apply_trivial(std::array<buffer_info, NVectorized> &buffers,
+                       std::array<void *, N> &params,
+                       Return *out,
+                       size_t size,
+                       index_sequence<Index...>, index_sequence<VIndex...>, index_sequence<BIndex...>) {
+
+        // Initialize an array of mutable byte references and sizes with references set to the
+        // appropriate pointer in `params`; as we iterate, we'll increment each pointer by its size
+        // (except for singletons, which get an increment of 0).
+        std::array<std::pair<unsigned char *&, const size_t>, NVectorized> vecparams{{
+            std::pair<unsigned char *&, const size_t>(
+                    reinterpret_cast<unsigned char *&>(params[VIndex] = buffers[BIndex].ptr),
+                    buffers[BIndex].size == 1 ? 0 : sizeof(param_n_t<VIndex>)
+            )...
+        }};
+
+        for (size_t i = 0; i < size; ++i) {
+            returned_array::call(out, i, f, *reinterpret_cast<param_n_t<Index> *>(params[Index])...);
+            for (auto &x : vecparams) x.first += x.second;
         }
-
-        return result;
     }
 
-    template <size_t... Index>
-    void apply_broadcast(const std::array<buffer_info, N> &buffers,
-                         buffer_info &output, index_sequence<Index...>) {
-        using input_iterator = multi_array_iterator<N>;
-        using output_iterator = array_iterator<Return>;
+    template <size_t... Index, size_t... VIndex, size_t... BIndex>
+    void apply_broadcast(std::array<buffer_info, NVectorized> &buffers,
+                         std::array<void *, N> &params,
+                         Return *out,
+                         size_t size,
+                         const std::vector<ssize_t> &output_shape,
+                         index_sequence<Index...>, index_sequence<VIndex...>, index_sequence<BIndex...>) {
 
-        input_iterator input_iter(buffers, output.shape);
-        output_iterator output_end = array_end<Return>(output);
+        multi_array_iterator<NVectorized> input_iter(buffers, output_shape);
 
-        for (output_iterator iter = array_begin<Return>(output);
-             iter != output_end; ++iter, ++input_iter) {
-            *iter = f((input_iter.template data<Index, Args>())...);
+        for (size_t i = 0; i < size; ++i, ++input_iter) {
+            PYBIND11_EXPAND_SIDE_EFFECTS((
+                params[VIndex] = input_iter.template data<BIndex>()
+            ));
+            returned_array::call(out, i, f, *reinterpret_cast<param_n_t<Index> *>(std::get<Index>(params))...);
         }
     }
 };
 
-template <typename T, int Flags> struct handle_type_name<array_t<T, Flags>> {
-    static PYBIND11_DESCR name() {
-        return _("numpy.ndarray[") + npy_format_descriptor<T>::name() + _("]");
-    }
-};
-
-NAMESPACE_END(detail)
-
 template <typename Func, typename Return, typename... Args>
-detail::vectorize_helper<Func, Return, Args...>
-vectorize(const Func &f, Return (*) (Args ...)) {
+vectorize_helper<Func, Return, Args...>
+vectorize_extractor(const Func &f, Return (*) (Args ...)) {
     return detail::vectorize_helper<Func, Return, Args...>(f);
 }
 
+template <typename T, int Flags> struct handle_type_name<array_t<T, Flags>> {
+    static constexpr auto name = _("numpy.ndarray[") + npy_format_descriptor<T>::name + _("]");
+};
+
+PYBIND11_NAMESPACE_END(detail)
+
+// Vanilla pointer vectorizer:
 template <typename Return, typename... Args>
-detail::vectorize_helper<Return (*) (Args ...), Return, Args...>
+detail::vectorize_helper<Return (*)(Args...), Return, Args...>
 vectorize(Return (*f) (Args ...)) {
-    return vectorize<Return (*) (Args ...), Return, Args...>(f, f);
+    return detail::vectorize_helper<Return (*)(Args...), Return, Args...>(f);
 }
 
-template <typename Func, typename FuncType = typename detail::remove_class<decltype(&std::remove_reference<Func>::type::operator())>::type>
+// lambda vectorizer:
+template <typename Func, detail::enable_if_t<detail::is_lambda<Func>::value, int> = 0>
 auto vectorize(Func &&f) -> decltype(
-        vectorize(std::forward<Func>(f), (FuncType *) nullptr)) {
-    return vectorize(std::forward<Func>(f), (FuncType *) nullptr);
+        detail::vectorize_extractor(std::forward<Func>(f), (detail::function_signature_t<Func> *) nullptr)) {
+    return detail::vectorize_extractor(std::forward<Func>(f), (detail::function_signature_t<Func> *) nullptr);
+}
+
+// Vectorize a class method (non-const):
+template <typename Return, typename Class, typename... Args,
+          typename Helper = detail::vectorize_helper<decltype(std::mem_fn(std::declval<Return (Class::*)(Args...)>())), Return, Class *, Args...>>
+Helper vectorize(Return (Class::*f)(Args...)) {
+    return Helper(std::mem_fn(f));
+}
+
+// Vectorize a class method (const):
+template <typename Return, typename Class, typename... Args,
+          typename Helper = detail::vectorize_helper<decltype(std::mem_fn(std::declval<Return (Class::*)(Args...) const>())), Return, const Class *, Args...>>
+Helper vectorize(Return (Class::*f)(Args...) const) {
+    return Helper(std::mem_fn(f));
 }
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
 #if defined(_MSC_VER)
 #pragma warning(pop)
diff --git a/libs/pybind/pybind11/operators.h b/libs/pybind/pybind11/operators.h
index 2e78c01a3f..086cb4cfd8 100644
--- a/libs/pybind/pybind11/operators.h
+++ b/libs/pybind/pybind11/operators.h
@@ -13,10 +13,13 @@
 
 #if defined(__clang__) && !defined(__INTEL_COMPILER)
 #  pragma clang diagnostic ignored "-Wunsequenced" // multiple unsequenced modifications to 'self' (when using def(py::self OP Type()))
+#elif defined(_MSC_VER)
+#  pragma warning(push)
+#  pragma warning(disable: 4127) // warning C4127: Conditional expression is constant
 #endif
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 /// Enumeration with all supported operator types
 enum op_id : int {
@@ -25,7 +28,7 @@ enum op_id : int {
     op_int, op_long, op_float, op_str, op_cmp, op_gt, op_ge, op_lt, op_le,
     op_eq, op_ne, op_iadd, op_isub, op_imul, op_idiv, op_imod, op_ilshift,
     op_irshift, op_iand, op_ixor, op_ior, op_complex, op_bool, op_nonzero,
-    op_repr, op_truediv
+    op_repr, op_truediv, op_itruediv, op_hash
 };
 
 enum op_type : int {
@@ -49,22 +52,32 @@ template <op_id, op_type, typename B, typename L, typename R> struct op_impl { }
 /// Operator implementation generator
 template <op_id id, op_type ot, typename L, typename R> struct op_ {
     template <typename Class, typename... Extra> void execute(Class &cl, const Extra&... extra) const {
-        typedef typename Class::type Base;
-        typedef typename std::conditional<std::is_same<L, self_t>::value, Base, L>::type L_type;
-        typedef typename std::conditional<std::is_same<R, self_t>::value, Base, R>::type R_type;
-        typedef op_impl<id, ot, Base, L_type, R_type> op;
+        using Base = typename Class::type;
+        using L_type = conditional_t<std::is_same<L, self_t>::value, Base, L>;
+        using R_type = conditional_t<std::is_same<R, self_t>::value, Base, R>;
+        using op = op_impl<id, ot, Base, L_type, R_type>;
         cl.def(op::name(), &op::execute, is_operator(), extra...);
+        #if PY_MAJOR_VERSION < 3
+        if (id == op_truediv || id == op_itruediv)
+            cl.def(id == op_itruediv ? "__idiv__" : ot == op_l ? "__div__" : "__rdiv__",
+                    &op::execute, is_operator(), extra...);
+        #endif
     }
     template <typename Class, typename... Extra> void execute_cast(Class &cl, const Extra&... extra) const {
-        typedef typename Class::type Base;
-        typedef typename std::conditional<std::is_same<L, self_t>::value, Base, L>::type L_type;
-        typedef typename std::conditional<std::is_same<R, self_t>::value, Base, R>::type R_type;
-        typedef op_impl<id, ot, Base, L_type, R_type> op;
+        using Base = typename Class::type;
+        using L_type = conditional_t<std::is_same<L, self_t>::value, Base, L>;
+        using R_type = conditional_t<std::is_same<R, self_t>::value, Base, R>;
+        using op = op_impl<id, ot, Base, L_type, R_type>;
         cl.def(op::name(), &op::execute_cast, is_operator(), extra...);
+        #if PY_MAJOR_VERSION < 3
+        if (id == op_truediv || id == op_itruediv)
+            cl.def(id == op_itruediv ? "__idiv__" : ot == op_l ? "__div__" : "__rdiv__",
+                    &op::execute, is_operator(), extra...);
+        #endif
     }
 };
 
-#define PYBIND11_BINARY_OPERATOR(id, rid, op, expr)                                      \
+#define PYBIND11_BINARY_OPERATOR(id, rid, op, expr)                                    \
 template <typename B, typename L, typename R> struct op_impl<op_##id, op_l, B, L, R> { \
     static char const* name() { return "__" #id "__"; }                                \
     static auto execute(const L &l, const R &r) -> decltype(expr) { return (expr); }   \
@@ -85,7 +98,7 @@ template <typename T> op_<op_##id, op_r, T, self_t> op(const T &, const self_t &
     return op_<op_##id, op_r, T, self_t>();                                            \
 }
 
-#define PYBIND11_INPLACE_OPERATOR(id, op, expr)                                          \
+#define PYBIND11_INPLACE_OPERATOR(id, op, expr)                                        \
 template <typename B, typename L, typename R> struct op_impl<op_##id, op_l, B, L, R> { \
     static char const* name() { return "__" #id "__"; }                                \
     static auto execute(L &l, const R &r) -> decltype(expr) { return expr; }           \
@@ -95,7 +108,7 @@ template <typename T> op_<op_##id, op_l, self_t, T> op(const self_t &, const T &
     return op_<op_##id, op_l, self_t, T>();                                            \
 }
 
-#define PYBIND11_UNARY_OPERATOR(id, op, expr)                                            \
+#define PYBIND11_UNARY_OPERATOR(id, op, expr)                                          \
 template <typename B, typename L> struct op_impl<op_##id, op_u, B, L, undefined_t> {   \
     static char const* name() { return "__" #id "__"; }                                \
     static auto execute(const L &l) -> decltype(expr) { return expr; }                 \
@@ -108,11 +121,7 @@ inline op_<op_##id, op_u, self_t, undefined_t> op(const self_t &) {
 PYBIND11_BINARY_OPERATOR(sub,       rsub,         operator-,    l - r)
 PYBIND11_BINARY_OPERATOR(add,       radd,         operator+,    l + r)
 PYBIND11_BINARY_OPERATOR(mul,       rmul,         operator*,    l * r)
-#if PY_MAJOR_VERSION >= 3
 PYBIND11_BINARY_OPERATOR(truediv,   rtruediv,     operator/,    l / r)
-#else
-PYBIND11_BINARY_OPERATOR(div,       rdiv,         operator/,    l / r)
-#endif
 PYBIND11_BINARY_OPERATOR(mod,       rmod,         operator%,    l % r)
 PYBIND11_BINARY_OPERATOR(lshift,    rlshift,      operator<<,   l << r)
 PYBIND11_BINARY_OPERATOR(rshift,    rrshift,      operator>>,   l >> r)
@@ -129,7 +138,7 @@ PYBIND11_BINARY_OPERATOR(le,        ge,           operator<=,   l <= r)
 PYBIND11_INPLACE_OPERATOR(iadd,     operator+=,   l += r)
 PYBIND11_INPLACE_OPERATOR(isub,     operator-=,   l -= r)
 PYBIND11_INPLACE_OPERATOR(imul,     operator*=,   l *= r)
-PYBIND11_INPLACE_OPERATOR(idiv,     operator/=,   l /= r)
+PYBIND11_INPLACE_OPERATOR(itruediv, operator/=,   l /= r)
 PYBIND11_INPLACE_OPERATOR(imod,     operator%=,   l %= r)
 PYBIND11_INPLACE_OPERATOR(ilshift,  operator<<=,  l <<= r)
 PYBIND11_INPLACE_OPERATOR(irshift,  operator>>=,  l >>= r)
@@ -138,7 +147,11 @@ PYBIND11_INPLACE_OPERATOR(ixor,     operator^=,   l ^= r)
 PYBIND11_INPLACE_OPERATOR(ior,      operator|=,   l |= r)
 PYBIND11_UNARY_OPERATOR(neg,        operator-,    -l)
 PYBIND11_UNARY_OPERATOR(pos,        operator+,    +l)
+// WARNING: This usage of `abs` should only be done for existing STL overloads.
+// Adding overloads directly in to the `std::` namespace is advised against:
+// https://en.cppreference.com/w/cpp/language/extending_std
 PYBIND11_UNARY_OPERATOR(abs,        abs,          std::abs(l))
+PYBIND11_UNARY_OPERATOR(hash,       hash,         std::hash<L>()(l))
 PYBIND11_UNARY_OPERATOR(invert,     operator~,    (~l))
 PYBIND11_UNARY_OPERATOR(bool,       operator!,    !!l)
 PYBIND11_UNARY_OPERATOR(int,        int_,         (int) l)
@@ -147,8 +160,14 @@ PYBIND11_UNARY_OPERATOR(float,      float_,       (double) l)
 #undef PYBIND11_BINARY_OPERATOR
 #undef PYBIND11_INPLACE_OPERATOR
 #undef PYBIND11_UNARY_OPERATOR
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 using detail::self;
+// Add named operators so that they are accessible via `py::`.
+using detail::hash;
+
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
-NAMESPACE_END(pybind11)
+#if defined(_MSC_VER)
+#  pragma warning(pop)
+#endif
diff --git a/libs/pybind/pybind11/options.h b/libs/pybind/pybind11/options.h
index 3105551ddd..d74db1c68d 100644
--- a/libs/pybind/pybind11/options.h
+++ b/libs/pybind/pybind11/options.h
@@ -9,9 +9,9 @@
 
 #pragma once
 
-#include "common.h"
+#include "detail/common.h"
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 class options {
 public:
@@ -62,4 +62,4 @@ class options {
     state previous_state;
 };
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/pybind11.h b/libs/pybind/pybind11/pybind11.h
index 5976a36d81..e2ddda020b 100644
--- a/libs/pybind/pybind11/pybind11.h
+++ b/libs/pybind/pybind11/pybind11.h
@@ -10,7 +10,17 @@
 
 #pragma once
 
-#if defined(_MSC_VER)
+#if defined(__INTEL_COMPILER)
+#  pragma warning push
+#  pragma warning disable 68    // integer conversion resulted in a change of sign
+#  pragma warning disable 186   // pointless comparison of unsigned integer with zero
+#  pragma warning disable 878   // incompatible exception specifications
+#  pragma warning disable 1334  // the "template" keyword used for syntactic disambiguation may only be used within a template
+#  pragma warning disable 1682  // implicit conversion of a 64-bit integral type to a smaller integral type (potential portability problem)
+#  pragma warning disable 1786  // function "strdup" was declared deprecated
+#  pragma warning disable 1875  // offsetof applied to non-POD (Plain Old Data) types is nonstandard
+#  pragma warning disable 2196  // warning #2196: routine is both "inline" and "noinline"
+#elif defined(_MSC_VER)
 #  pragma warning(push)
 #  pragma warning(disable: 4100) // warning C4100: Unreferenced formal parameter
 #  pragma warning(disable: 4127) // warning C4127: Conditional expression is constant
@@ -19,11 +29,7 @@
 #  pragma warning(disable: 4996) // warning C4996: The POSIX name for this item is deprecated. Instead, use the ISO C and C++ conformant name
 #  pragma warning(disable: 4702) // warning C4702: unreachable code
 #  pragma warning(disable: 4522) // warning C4522: multiple assignment operators specified
-#elif defined(__INTEL_COMPILER)
-#  pragma warning(push)
-#  pragma warning(disable: 186)   // pointless comparison of unsigned integer with zero
-#  pragma warning(disable: 1334)  // the "template" keyword used for syntactic disambiguation may only be used within a template
-#  pragma warning(disable: 2196)  // warning #2196: routine is both "inline" and "noinline"
+#  pragma warning(disable: 4505) // warning C4505: 'PySlice_GetIndicesEx': unreferenced local function has been removed (PyPy only)
 #elif defined(__GNUG__) && !defined(__clang__)
 #  pragma GCC diagnostic push
 #  pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
@@ -31,18 +37,32 @@
 #  pragma GCC diagnostic ignored "-Wmissing-field-initializers"
 #  pragma GCC diagnostic ignored "-Wstrict-aliasing"
 #  pragma GCC diagnostic ignored "-Wattributes"
+#  if __GNUC__ >= 7
+#    pragma GCC diagnostic ignored "-Wnoexcept-type"
+#  endif
 #endif
 
 #include "attr.h"
 #include "options.h"
-#include "class_support.h"
+#include "detail/class.h"
+#include "detail/init.h"
+
+#include <memory>
+#include <vector>
+#include <string>
+#include <utility>
+
+#if defined(__GNUG__) && !defined(__clang__)
+#  include <cxxabi.h>
+#endif
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 /// Wraps an arbitrary C++ function/method/lambda function/.. into a callable Python object
 class cpp_function : public function {
 public:
-    cpp_function() { }
+    cpp_function() = default;
+    cpp_function(std::nullptr_t) { }
 
     /// Construct a cpp_function from a vanilla function pointer
     template <typename Return, typename... Args, typename... Extra>
@@ -51,28 +71,41 @@ class cpp_function : public function {
     }
 
     /// Construct a cpp_function from a lambda function (possibly with internal state)
-    template <typename Func, typename... Extra, typename = detail::enable_if_t<
-        detail::satisfies_none_of<
-            typename std::remove_reference<Func>::type,
-            std::is_function, std::is_pointer, std::is_member_pointer
-        >::value>
-    >
+    template <typename Func, typename... Extra,
+              typename = detail::enable_if_t<detail::is_lambda<Func>::value>>
     cpp_function(Func &&f, const Extra&... extra) {
-        using FuncType = typename detail::remove_class<decltype(&std::remove_reference<Func>::type::operator())>::type;
         initialize(std::forward<Func>(f),
-                   (FuncType *) nullptr, extra...);
+                   (detail::function_signature_t<Func> *) nullptr, extra...);
     }
 
-    /// Construct a cpp_function from a class method (non-const)
+    /// Construct a cpp_function from a class method (non-const, no ref-qualifier)
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     cpp_function(Return (Class::*f)(Arg...), const Extra&... extra) {
+        initialize([f](Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
+                   (Return (*) (Class *, Arg...)) nullptr, extra...);
+    }
+
+    /// Construct a cpp_function from a class method (non-const, lvalue ref-qualifier)
+    /// A copy of the overload for non-const functions without explicit ref-qualifier
+    /// but with an added `&`.
+    template <typename Return, typename Class, typename... Arg, typename... Extra>
+    cpp_function(Return (Class::*f)(Arg...)&, const Extra&... extra) {
         initialize([f](Class *c, Arg... args) -> Return { return (c->*f)(args...); },
                    (Return (*) (Class *, Arg...)) nullptr, extra...);
     }
 
-    /// Construct a cpp_function from a class method (const)
+    /// Construct a cpp_function from a class method (const, no ref-qualifier)
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     cpp_function(Return (Class::*f)(Arg...) const, const Extra&... extra) {
+        initialize([f](const Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
+                   (Return (*)(const Class *, Arg ...)) nullptr, extra...);
+    }
+
+    /// Construct a cpp_function from a class method (const, lvalue ref-qualifier)
+    /// A copy of the overload for const functions without explicit ref-qualifier
+    /// but with an added `&`.
+    template <typename Return, typename Class, typename... Arg, typename... Extra>
+    cpp_function(Return (Class::*f)(Arg...) const&, const Extra&... extra) {
         initialize([f](const Class *c, Arg... args) -> Return { return (c->*f)(args...); },
                    (Return (*)(const Class *, Arg ...)) nullptr, extra...);
     }
@@ -89,8 +122,8 @@ class cpp_function : public function {
     /// Special internal constructor for functors, lambda functions, etc.
     template <typename Func, typename Return, typename... Args, typename... Extra>
     void initialize(Func &&f, Return (*)(Args...), const Extra&... extra) {
-
-        struct capture { typename std::remove_reference<Func>::type f; };
+        using namespace detail;
+        struct capture { remove_reference_t<Func> f; };
 
         /* Store the function including any extra state it might have (e.g. a lambda capture object) */
         auto rec = make_function_record();
@@ -109,23 +142,23 @@ class cpp_function : public function {
 #  pragma GCC diagnostic pop
 #endif
             if (!std::is_trivially_destructible<Func>::value)
-                rec->free_data = [](detail::function_record *r) { ((capture *) &r->data)->~capture(); };
+                rec->free_data = [](function_record *r) { ((capture *) &r->data)->~capture(); };
         } else {
             rec->data[0] = new capture { std::forward<Func>(f) };
-            rec->free_data = [](detail::function_record *r) { delete ((capture *) r->data[0]); };
+            rec->free_data = [](function_record *r) { delete ((capture *) r->data[0]); };
         }
 
         /* Type casters for the function arguments and return value */
-        using cast_in = detail::argument_loader<Args...>;
-        using cast_out = detail::make_caster<
-            detail::conditional_t<std::is_void<Return>::value, detail::void_type, Return>
+        using cast_in = argument_loader<Args...>;
+        using cast_out = make_caster<
+            conditional_t<std::is_void<Return>::value, void_type, Return>
         >;
 
-        static_assert(detail::expected_num_args<Extra...>(sizeof...(Args), cast_in::has_args, cast_in::has_kwargs),
+        static_assert(expected_num_args<Extra...>(sizeof...(Args), cast_in::has_args, cast_in::has_kwargs),
                       "The number of argument annotations does not match the number of function arguments");
 
         /* Dispatch code which converts function arguments and performs the actual function call */
-        rec->impl = [](detail::function_call &call) -> handle {
+        rec->impl = [](function_call &call) -> handle {
             cast_in args_converter;
 
             /* Try to cast the function arguments into the C++ domain */
@@ -133,35 +166,48 @@ class cpp_function : public function {
                 return PYBIND11_TRY_NEXT_OVERLOAD;
 
             /* Invoke call policy pre-call hook */
-            detail::process_attributes<Extra...>::precall(call);
+            process_attributes<Extra...>::precall(call);
 
             /* Get a pointer to the capture object */
             auto data = (sizeof(capture) <= sizeof(call.func.data)
                          ? &call.func.data : call.func.data[0]);
-            capture *cap = const_cast<capture *>(reinterpret_cast<const capture *>(data));
+            auto *cap = const_cast<capture *>(reinterpret_cast<const capture *>(data));
 
             /* Override policy for rvalues -- usually to enforce rvp::move on an rvalue */
-            const auto policy = detail::return_value_policy_override<Return>::policy(call.func.policy);
+            return_value_policy policy = return_value_policy_override<Return>::policy(call.func.policy);
+
+            /* Function scope guard -- defaults to the compile-to-nothing `void_type` */
+            using Guard = extract_guard_t<Extra...>;
 
             /* Perform the function call */
-            handle result = cast_out::cast(args_converter.template call<Return>(cap->f),
-                                           policy, call.parent);
+            handle result = cast_out::cast(
+                std::move(args_converter).template call<Return, Guard>(cap->f), policy, call.parent);
 
             /* Invoke call policy post-call hook */
-            detail::process_attributes<Extra...>::postcall(call, result);
+            process_attributes<Extra...>::postcall(call, result);
 
             return result;
         };
 
         /* Process any user-provided function attributes */
-        detail::process_attributes<Extra...>::init(extra..., rec);
+        process_attributes<Extra...>::init(extra..., rec);
+
+        {
+            constexpr bool has_kw_only_args = any_of<std::is_same<kw_only, Extra>...>::value,
+                           has_pos_only_args = any_of<std::is_same<pos_only, Extra>...>::value,
+                           has_args = any_of<std::is_same<args, Args>...>::value,
+                           has_arg_annotations = any_of<is_keyword<Extra>...>::value;
+            static_assert(has_arg_annotations || !has_kw_only_args, "py::kw_only requires the use of argument annotations");
+            static_assert(has_arg_annotations || !has_pos_only_args, "py::pos_only requires the use of argument annotations (for docstrings and aligning the annotations to the argument)");
+            static_assert(!(has_args && has_kw_only_args), "py::kw_only cannot be combined with a py::args argument");
+        }
 
         /* Generate a readable signature describing the function's arguments and return value types */
-        using detail::descr; using detail::_;
-        PYBIND11_DESCR signature = _("(") + cast_in::arg_names() + _(") -> ") + cast_out::name();
+        static constexpr auto signature = _("(") + cast_in::arg_names + _(") -> ") + cast_out::name;
+        PYBIND11_DESCR_CONSTEXPR auto types = decltype(signature)::types();
 
         /* Register the function with Python from generic (non-templated) code */
-        initialize_generic(rec, signature.text(), signature.types(), sizeof...(Args));
+        initialize_generic(rec, signature.text, types.data(), sizeof...(Args));
 
         if (cast_in::has_args) rec->has_args = true;
         if (cast_in::has_kwargs) rec->has_kwargs = true;
@@ -190,50 +236,73 @@ class cpp_function : public function {
             if (a.descr)
                 a.descr = strdup(a.descr);
             else if (a.value)
-                a.descr = strdup(a.value.attr("__repr__")().cast<std::string>().c_str());
+                a.descr = strdup(repr(a.value).cast<std::string>().c_str());
         }
 
+        rec->is_constructor = !strcmp(rec->name, "__init__") || !strcmp(rec->name, "__setstate__");
+
+#if !defined(NDEBUG) && !defined(PYBIND11_DISABLE_NEW_STYLE_INIT_WARNING)
+        if (rec->is_constructor && !rec->is_new_style_constructor) {
+            const auto class_name = detail::get_fully_qualified_tp_name((PyTypeObject *) rec->scope.ptr());
+            const auto func_name = std::string(rec->name);
+            PyErr_WarnEx(
+                PyExc_FutureWarning,
+                ("pybind11-bound class '" + class_name + "' is using an old-style "
+                 "placement-new '" + func_name + "' which has been deprecated. See "
+                 "the upgrade guide in pybind11's docs. This message is only visible "
+                 "when compiled in debug mode.").c_str(), 0
+            );
+        }
+#endif
+
         /* Generate a proper function signature */
         std::string signature;
-        size_t type_depth = 0, char_index = 0, type_index = 0, arg_index = 0;
-        while (true) {
-            char c = text[char_index++];
-            if (c == '\0')
-                break;
+        size_t type_index = 0, arg_index = 0;
+        for (auto *pc = text; *pc != '\0'; ++pc) {
+            const auto c = *pc;
 
             if (c == '{') {
-                // Write arg name for everything except *args, **kwargs and return type.
-                if (type_depth == 0 && text[char_index] != '*' && arg_index < args) {
-                    if (!rec->args.empty() && rec->args[arg_index].name) {
-                        signature += rec->args[arg_index].name;
-                    } else if (arg_index == 0 && rec->is_method) {
-                        signature += "self";
-                    } else {
-                        signature += "arg" + std::to_string(arg_index - (rec->is_method ? 1 : 0));
-                    }
-                    signature += ": ";
+                // Write arg name for everything except *args and **kwargs.
+                if (*(pc + 1) == '*')
+                    continue;
+                // Separator for keyword-only arguments, placed before the kw
+                // arguments start
+                if (rec->nargs_kw_only > 0 && arg_index + rec->nargs_kw_only == args)
+                    signature += "*, ";
+                if (arg_index < rec->args.size() && rec->args[arg_index].name) {
+                    signature += rec->args[arg_index].name;
+                } else if (arg_index == 0 && rec->is_method) {
+                    signature += "self";
+                } else {
+                    signature += "arg" + std::to_string(arg_index - (rec->is_method ? 1 : 0));
                 }
-                ++type_depth;
+                signature += ": ";
             } else if (c == '}') {
-                --type_depth;
-                if (type_depth == 0) {
-                    if (arg_index < rec->args.size() && rec->args[arg_index].descr) {
-                        signature += "=";
-                        signature += rec->args[arg_index].descr;
-                    }
-                    arg_index++;
+                // Write default value if available.
+                if (arg_index < rec->args.size() && rec->args[arg_index].descr) {
+                    signature += " = ";
+                    signature += rec->args[arg_index].descr;
                 }
+                // Separator for positional-only arguments (placed after the
+                // argument, rather than before like *
+                if (rec->nargs_pos_only > 0 && (arg_index + 1) == rec->nargs_pos_only)
+                    signature += ", /";
+                arg_index++;
             } else if (c == '%') {
                 const std::type_info *t = types[type_index++];
                 if (!t)
                     pybind11_fail("Internal error while parsing type signature (1)");
                 if (auto tinfo = detail::get_type_info(*t)) {
-#if defined(PYPY_VERSION)
-                    signature += handle((PyObject *) tinfo->type)
-                                     .attr("__module__")
-                                     .cast<std::string>() + ".";
-#endif
-                    signature += tinfo->type->tp_name;
+                    handle th((PyObject *) tinfo->type);
+                    signature +=
+                        th.attr("__module__").cast<std::string>() + "." +
+                        th.attr("__qualname__").cast<std::string>(); // Python 3.3+, but we backport it to earlier versions
+                } else if (rec->is_new_style_constructor && arg_index == 0) {
+                    // A new-style `__init__` takes `self` as `value_and_holder`.
+                    // Rewrite it to the proper class type.
+                    signature +=
+                        rec->scope.attr("__module__").cast<std::string>() + "." +
+                        rec->scope.attr("__qualname__").cast<std::string>();
                 } else {
                     std::string tname(t->name());
                     detail::clean_type_id(tname);
@@ -243,13 +312,9 @@ class cpp_function : public function {
                 signature += c;
             }
         }
-        if (type_depth != 0 || types[type_index] != nullptr)
-            pybind11_fail("Internal error while parsing type signature (2)");
 
-        #if !defined(PYBIND11_CPP14)
-            delete[] types;
-            delete[] text;
-        #endif
+        if (arg_index != args || types[type_index] != nullptr)
+            pybind11_fail("Internal error while parsing type signature (2)");
 
 #if PY_MAJOR_VERSION < 3
         if (strcmp(rec->name, "__next__") == 0) {
@@ -262,13 +327,10 @@ class cpp_function : public function {
 #endif
         rec->signature = strdup(signature.c_str());
         rec->args.shrink_to_fit();
-        rec->is_constructor = !strcmp(rec->name, "__init__") || !strcmp(rec->name, "__setstate__");
         rec->nargs = (std::uint16_t) args;
 
-#if PY_MAJOR_VERSION < 3
-        if (rec->sibling && PyMethod_Check(rec->sibling.ptr()))
-            rec->sibling = PyMethod_GET_FUNCTION(rec->sibling.ptr());
-#endif
+        if (rec->sibling && PYBIND11_INSTANCE_METHOD_CHECK(rec->sibling.ptr()))
+            rec->sibling = PYBIND11_INSTANCE_METHOD_GET_FUNCTION(rec->sibling.ptr());
 
         detail::function_record *chain = nullptr, *chain_start = rec;
         if (rec->sibling) {
@@ -277,7 +339,7 @@ class cpp_function : public function {
                 chain = (detail::function_record *) rec_capsule;
                 /* Never append a method to an overload chain of a parent class;
                    instead, hide the parent's overloads in this case */
-                if (chain->scope != rec->scope)
+                if (!chain->scope.is(rec->scope))
                     chain = nullptr;
             }
             // Don't trigger for things like the default __init__, which are wrapper_descriptors that we are intentionally replacing
@@ -289,9 +351,9 @@ class cpp_function : public function {
         if (!chain) {
             /* No existing overload was found, create a new function object */
             rec->def = new PyMethodDef();
-            memset(rec->def, 0, sizeof(PyMethodDef));
+            std::memset(rec->def, 0, sizeof(PyMethodDef));
             rec->def->ml_name = rec->name;
-            rec->def->ml_meth = reinterpret_cast<PyCFunction>(*dispatcher);
+            rec->def->ml_meth = reinterpret_cast<PyCFunction>(reinterpret_cast<void (*) (void)>(*dispatcher));
             rec->def->ml_flags = METH_VARARGS | METH_KEYWORDS;
 
             capsule rec_capsule(rec, [](void *ptr) {
@@ -311,13 +373,34 @@ class cpp_function : public function {
             if (!m_ptr)
                 pybind11_fail("cpp_function::cpp_function(): Could not allocate function object");
         } else {
-            /* Append at the end of the overload chain */
+            /* Append at the beginning or end of the overload chain */
             m_ptr = rec->sibling.ptr();
             inc_ref();
-            chain_start = chain;
-            while (chain->next)
-                chain = chain->next;
-            chain->next = rec;
+            if (chain->is_method != rec->is_method)
+                pybind11_fail("overloading a method with both static and instance methods is not supported; "
+                    #if defined(NDEBUG)
+                        "compile in debug mode for more details"
+                    #else
+                        "error while attempting to bind " + std::string(rec->is_method ? "instance" : "static") + " method " +
+                        std::string(pybind11::str(rec->scope.attr("__name__"))) + "." + std::string(rec->name) + signature
+                    #endif
+                );
+
+            if (rec->prepend) {
+                // Beginning of chain; we need to replace the capsule's current head-of-the-chain
+                // pointer with this one, then make this one point to the previous head of the
+                // chain.
+                chain_start = rec;
+                rec->next = chain;
+                auto rec_capsule = reinterpret_borrow<capsule>(((PyCFunctionObject *) m_ptr)->m_self);
+                rec_capsule.set_pointer(rec);
+            } else {
+                // Or end of chain (normal behavior)
+                chain_start = chain;
+                while (chain->next)
+                    chain = chain->next;
+                chain->next = rec;
+            }
         }
 
         std::string signatures;
@@ -355,7 +438,7 @@ class cpp_function : public function {
         }
 
         /* Install docstring */
-        PyCFunctionObject *func = (PyCFunctionObject *) m_ptr;
+        auto *func = (PyCFunctionObject *) m_ptr;
         if (func->m_ml->ml_doc)
             std::free(const_cast<char *>(func->m_ml->ml_doc));
         func->m_ml->ml_doc = strdup(signatures.c_str());
@@ -370,6 +453,12 @@ class cpp_function : public function {
 
     /// When a cpp_function is GCed, release any memory allocated by pybind11
     static void destruct(detail::function_record *rec) {
+        // If on Python 3.9, check the interpreter "MICRO" (patch) version.
+        // If this is running on 3.9.0, we have to work around a bug.
+        #if !defined(PYPY_VERSION) && PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION == 9
+            static bool is_zero = Py_GetVersion()[4] == '0';
+        #endif
+
         while (rec) {
             detail::function_record *next = rec->next;
             if (rec->free_data)
@@ -384,7 +473,15 @@ class cpp_function : public function {
             }
             if (rec->def) {
                 std::free(const_cast<char *>(rec->def->ml_doc));
-                delete rec->def;
+                // Python 3.9.0 decref's these in the wrong order; rec->def
+                // If loaded on 3.9.0, let these leak (use Python 3.9.1 at runtime to fix)
+                // See https://github.com/python/cpython/pull/22670
+                #if !defined(PYPY_VERSION) && PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION == 9
+                    if (!is_zero)
+                        delete rec->def;
+                #else
+                    delete rec->def;
+                #endif
             }
             delete rec;
             rec = next;
@@ -396,15 +493,32 @@ class cpp_function : public function {
         using namespace detail;
 
         /* Iterator over the list of potentially admissible overloads */
-        function_record *overloads = (function_record *) PyCapsule_GetPointer(self, nullptr),
-                        *it = overloads;
+        const function_record *overloads = (function_record *) PyCapsule_GetPointer(self, nullptr),
+                              *it = overloads;
 
         /* Need to know how many arguments + keyword arguments there are to pick the right overload */
-        const size_t n_args_in = (size_t) PyTuple_GET_SIZE(args_in);
+        const auto n_args_in = (size_t) PyTuple_GET_SIZE(args_in);
 
         handle parent = n_args_in > 0 ? PyTuple_GET_ITEM(args_in, 0) : nullptr,
                result = PYBIND11_TRY_NEXT_OVERLOAD;
 
+        auto self_value_and_holder = value_and_holder();
+        if (overloads->is_constructor) {
+            const auto tinfo = get_type_info((PyTypeObject *) overloads->scope.ptr());
+            const auto pi = reinterpret_cast<instance *>(parent.ptr());
+            self_value_and_holder = pi->get_value_and_holder(tinfo, false);
+
+            if (!self_value_and_holder.type || !self_value_and_holder.inst) {
+                PyErr_SetString(PyExc_TypeError, "__init__(self, ...) called with invalid `self` argument");
+                return nullptr;
+            }
+
+            // If this value is already registered it must mean __init__ is invoked multiple times;
+            // we really can't support that in C++, so just ignore the second __init__.
+            if (self_value_and_holder.instance_registered())
+                return none().release().ptr();
+        }
+
         try {
             // We do this in two passes: in the first pass, we load arguments with `convert=false`;
             // in the second, we allow conversion (except for arguments with an explicit
@@ -436,50 +550,89 @@ class cpp_function : public function {
                    result other than PYBIND11_TRY_NEXT_OVERLOAD.
                  */
 
-                function_record &func = *it;
-                size_t pos_args = func.nargs;    // Number of positional arguments that we need
-                if (func.has_args) --pos_args;   // (but don't count py::args
-                if (func.has_kwargs) --pos_args; //  or py::kwargs)
+                const function_record &func = *it;
+                size_t num_args = func.nargs;    // Number of positional arguments that we need
+                if (func.has_args) --num_args;   // (but don't count py::args
+                if (func.has_kwargs) --num_args; //  or py::kwargs)
+                size_t pos_args = num_args - func.nargs_kw_only;
 
                 if (!func.has_args && n_args_in > pos_args)
-                    continue; // Too many arguments for this overload
+                    continue; // Too many positional arguments for this overload
 
                 if (n_args_in < pos_args && func.args.size() < pos_args)
-                    continue; // Not enough arguments given, and not enough defaults to fill in the blanks
+                    continue; // Not enough positional arguments given, and not enough defaults to fill in the blanks
 
                 function_call call(func, parent);
 
-                size_t args_to_copy = std::min(pos_args, n_args_in);
+                size_t args_to_copy = (std::min)(pos_args, n_args_in); // Protect std::min with parentheses
                 size_t args_copied = 0;
 
+                // 0. Inject new-style `self` argument
+                if (func.is_new_style_constructor) {
+                    // The `value` may have been preallocated by an old-style `__init__`
+                    // if it was a preceding candidate for overload resolution.
+                    if (self_value_and_holder)
+                        self_value_and_holder.type->dealloc(self_value_and_holder);
+
+                    call.init_self = PyTuple_GET_ITEM(args_in, 0);
+                    call.args.emplace_back(reinterpret_cast<PyObject *>(&self_value_and_holder));
+                    call.args_convert.push_back(false);
+                    ++args_copied;
+                }
+
                 // 1. Copy any position arguments given.
-                bool bad_kwarg = false;
+                bool bad_arg = false;
                 for (; args_copied < args_to_copy; ++args_copied) {
-                    if (kwargs_in && args_copied < func.args.size() && func.args[args_copied].name
-                            && PyDict_GetItemString(kwargs_in, func.args[args_copied].name)) {
-                        bad_kwarg = true;
+                    const argument_record *arg_rec = args_copied < func.args.size() ? &func.args[args_copied] : nullptr;
+                    if (kwargs_in && arg_rec && arg_rec->name && PyDict_GetItemString(kwargs_in, arg_rec->name)) {
+                        bad_arg = true;
                         break;
                     }
 
-                    call.args.push_back(PyTuple_GET_ITEM(args_in, args_copied));
-                    call.args_convert.push_back(args_copied < func.args.size() ? func.args[args_copied].convert : true);
+                    handle arg(PyTuple_GET_ITEM(args_in, args_copied));
+                    if (arg_rec && !arg_rec->none && arg.is_none()) {
+                        bad_arg = true;
+                        break;
+                    }
+                    call.args.push_back(arg);
+                    call.args_convert.push_back(arg_rec ? arg_rec->convert : true);
                 }
-                if (bad_kwarg)
+                if (bad_arg)
                     continue; // Maybe it was meant for another overload (issue #688)
 
                 // We'll need to copy this if we steal some kwargs for defaults
                 dict kwargs = reinterpret_borrow<dict>(kwargs_in);
 
+                // 1.5. Fill in any missing pos_only args from defaults if they exist
+                if (args_copied < func.nargs_pos_only) {
+                    for (; args_copied < func.nargs_pos_only; ++args_copied) {
+                        const auto &arg_rec = func.args[args_copied];
+                        handle value;
+
+                        if (arg_rec.value) {
+                            value = arg_rec.value;
+                        }
+                        if (value) {
+                            call.args.push_back(value);
+                            call.args_convert.push_back(arg_rec.convert);
+                        } else
+                            break;
+                    }
+
+                    if (args_copied < func.nargs_pos_only)
+                        continue; // Not enough defaults to fill the positional arguments
+                }
+
                 // 2. Check kwargs and, failing that, defaults that may help complete the list
-                if (args_copied < pos_args) {
+                if (args_copied < num_args) {
                     bool copied_kwargs = false;
 
-                    for (; args_copied < pos_args; ++args_copied) {
-                        const auto &arg = func.args[args_copied];
+                    for (; args_copied < num_args; ++args_copied) {
+                        const auto &arg_rec = func.args[args_copied];
 
                         handle value;
-                        if (kwargs_in && arg.name)
-                            value = PyDict_GetItemString(kwargs.ptr(), arg.name);
+                        if (kwargs_in && arg_rec.name)
+                            value = PyDict_GetItemString(kwargs.ptr(), arg_rec.name);
 
                         if (value) {
                             // Consume a kwargs value
@@ -487,30 +640,34 @@ class cpp_function : public function {
                                 kwargs = reinterpret_steal<dict>(PyDict_Copy(kwargs.ptr()));
                                 copied_kwargs = true;
                             }
-                            PyDict_DelItemString(kwargs.ptr(), arg.name);
-                        } else if (arg.value) {
-                            value = arg.value;
+                            PyDict_DelItemString(kwargs.ptr(), arg_rec.name);
+                        } else if (arg_rec.value) {
+                            value = arg_rec.value;
+                        }
+
+                        if (!arg_rec.none && value.is_none()) {
+                            break;
                         }
 
                         if (value) {
                             call.args.push_back(value);
-                            call.args_convert.push_back(arg.convert);
+                            call.args_convert.push_back(arg_rec.convert);
                         }
                         else
                             break;
                     }
 
-                    if (args_copied < pos_args)
+                    if (args_copied < num_args)
                         continue; // Not enough arguments, defaults, or kwargs to fill the positional arguments
                 }
 
                 // 3. Check everything was consumed (unless we have a kwargs arg)
-                if (kwargs && kwargs.size() > 0 && !func.has_kwargs)
+                if (kwargs && !kwargs.empty() && !func.has_kwargs)
                     continue; // Unconsumed kwargs, but no py::kwargs argument to accept them
 
                 // 4a. If we have a py::args argument, create a new tuple with leftovers
-                tuple extra_args;
                 if (func.has_args) {
+                    tuple extra_args;
                     if (args_to_copy == 0) {
                         // We didn't copy out any position arguments from the args_in tuple, so we
                         // can reuse it directly without copying:
@@ -521,12 +678,12 @@ class cpp_function : public function {
                         size_t args_size = n_args_in - args_copied;
                         extra_args = tuple(args_size);
                         for (size_t i = 0; i < args_size; ++i) {
-                            handle item = PyTuple_GET_ITEM(args_in, args_copied + i);
-                            extra_args[i] = item.inc_ref().ptr();
+                            extra_args[i] = PyTuple_GET_ITEM(args_in, args_copied + i);
                         }
                     }
                     call.args.push_back(extra_args);
                     call.args_convert.push_back(false);
+                    call.args_ref = std::move(extra_args);
                 }
 
                 // 4b. If we have a py::kwargs, pass on any remaining kwargs
@@ -535,6 +692,7 @@ class cpp_function : public function {
                         kwargs = dict(); // If we didn't get one, send an empty one
                     call.args.push_back(kwargs);
                     call.args_convert.push_back(false);
+                    call.kwargs_ref = std::move(kwargs);
                 }
 
                 // 5. Put everything in a vector.  Not technically step 5, we've been building it
@@ -555,6 +713,7 @@ class cpp_function : public function {
 
                 // 6. Call the function.
                 try {
+                    loader_life_support guard{};
                     result = func.impl(call);
                 } catch (reference_cast_error &) {
                     result = PYBIND11_TRY_NEXT_OVERLOAD;
@@ -583,18 +742,28 @@ class cpp_function : public function {
                 // The no-conversion pass finished without success, try again with conversion allowed
                 for (auto &call : second_pass) {
                     try {
+                        loader_life_support guard{};
                         result = call.func.impl(call);
                     } catch (reference_cast_error &) {
                         result = PYBIND11_TRY_NEXT_OVERLOAD;
                     }
 
-                    if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD)
+                    if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD) {
+                        // The error reporting logic below expects 'it' to be valid, as it would be
+                        // if we'd encountered this failure in the first-pass loop.
+                        if (!result)
+                            it = &call.func;
                         break;
+                    }
                 }
             }
         } catch (error_already_set &e) {
             e.restore();
             return nullptr;
+#ifdef __GLIBCXX__
+        } catch ( abi::__forced_unwind& ) {
+            throw;
+#endif
         } catch (...) {
             /* When an exception is caught, give each registered exception
                translator a chance to translate it to a Python exception
@@ -622,6 +791,16 @@ class cpp_function : public function {
             return nullptr;
         }
 
+        auto append_note_if_missing_header_is_suspected = [](std::string &msg) {
+            if (msg.find("std::") != std::string::npos) {
+                msg += "\n\n"
+                       "Did you forget to `#include <pybind11/stl.h>`? Or <pybind11/complex.h>,\n"
+                       "<pybind11/functional.h>, <pybind11/chrono.h>, etc. Some automatic\n"
+                       "conversions are optional and require extra headers to be included\n"
+                       "when compiling your pybind11 module.";
+            }
+        };
+
         if (result.ptr() == PYBIND11_TRY_NEXT_OVERLOAD) {
             if (overloads->is_operator)
                 return handle(Py_NotImplemented).inc_ref().ptr();
@@ -631,7 +810,7 @@ class cpp_function : public function {
                 " arguments. The following argument types are supported:\n";
 
             int ctr = 0;
-            for (function_record *it2 = overloads; it2 != nullptr; it2 = it2->next) {
+            for (const function_record *it2 = overloads; it2 != nullptr; it2 = it2->next) {
                 msg += "    "+ std::to_string(++ctr) + ". ";
 
                 bool wrote_sig = false;
@@ -663,36 +842,45 @@ class cpp_function : public function {
             for (size_t ti = overloads->is_constructor ? 1 : 0; ti < args_.size(); ++ti) {
                 if (!some_args) some_args = true;
                 else msg += ", ";
-                msg += pybind11::repr(args_[ti]);
+                try {
+                    msg += pybind11::repr(args_[ti]);
+                } catch (const error_already_set&) {
+                    msg += "<repr raised Error>";
+                }
             }
             if (kwargs_in) {
                 auto kwargs = reinterpret_borrow<dict>(kwargs_in);
-                if (kwargs.size() > 0) {
+                if (!kwargs.empty()) {
                     if (some_args) msg += "; ";
                     msg += "kwargs: ";
                     bool first = true;
                     for (auto kwarg : kwargs) {
                         if (first) first = false;
                         else msg += ", ";
-                        msg += pybind11::str("{}={!r}").format(kwarg.first, kwarg.second);
+                        msg += pybind11::str("{}=").format(kwarg.first);
+                        try {
+                            msg += pybind11::repr(kwarg.second);
+                        } catch (const error_already_set&) {
+                            msg += "<repr raised Error>";
+                        }
                     }
                 }
             }
 
+            append_note_if_missing_header_is_suspected(msg);
             PyErr_SetString(PyExc_TypeError, msg.c_str());
             return nullptr;
         } else if (!result) {
             std::string msg = "Unable to convert function return value to a "
                               "Python type! The signature was\n\t";
             msg += it->signature;
+            append_note_if_missing_header_is_suspected(msg);
             PyErr_SetString(PyExc_TypeError, msg.c_str());
             return nullptr;
         } else {
-            if (overloads->is_constructor) {
-                /* When a constructor ran successfully, the corresponding
-                   holder type (e.g. std::unique_ptr) must still be initialized. */
-                auto tinfo = get_type_info(Py_TYPE(parent.ptr()));
-                tinfo->init_holder(parent.ptr(), nullptr);
+            if (overloads->is_constructor && !self_value_and_holder.holder_constructed()) {
+                auto *pi = reinterpret_cast<instance *>(parent.ptr());
+                self_value_and_holder.type->init_instance(pi, nullptr);
             }
             return result.ptr();
         }
@@ -700,27 +888,18 @@ class cpp_function : public function {
 };
 
 /// Wrapper for Python extension modules
-class module : public object {
+class module_ : public object {
 public:
-    PYBIND11_OBJECT_DEFAULT(module, object, PyModule_Check)
+    PYBIND11_OBJECT_DEFAULT(module_, object, PyModule_Check)
 
     /// Create a new top-level Python module with the given name and docstring
-    explicit module(const char *name, const char *doc = nullptr) {
-        if (!options::show_user_defined_docstrings()) doc = nullptr;
+    PYBIND11_DEPRECATED("Use PYBIND11_MODULE or module_::create_extension_module instead")
+    explicit module_(const char *name, const char *doc = nullptr) {
 #if PY_MAJOR_VERSION >= 3
-        PyModuleDef *def = new PyModuleDef();
-        memset(def, 0, sizeof(PyModuleDef));
-        def->m_name = name;
-        def->m_doc = doc;
-        def->m_size = -1;
-        Py_INCREF(def);
-        m_ptr = PyModule_Create(def);
+        *this = create_extension_module(name, doc, new PyModuleDef());
 #else
-        m_ptr = Py_InitModule3(name, nullptr, doc);
+        *this = create_extension_module(name, doc, nullptr);
 #endif
-        if (m_ptr == nullptr)
-            pybind11_fail("Internal error in module::module()");
-        inc_ref();
     }
 
     /** \rst
@@ -729,7 +908,7 @@ class module : public object {
         details on the ``Extra&& ... extra`` argument, see section :ref:`extras`.
     \endrst */
     template <typename Func, typename... Extra>
-    module &def(const char *name_, Func &&f, const Extra& ... extra) {
+    module_ &def(const char *name_, Func &&f, const Extra& ... extra) {
         cpp_function func(std::forward<Func>(f), name(name_), scope(*this),
                           sibling(getattr(*this, name_, none())), extra...);
         // NB: allow overwriting here because cpp_function sets up a chain with the intention of
@@ -744,14 +923,14 @@ class module : public object {
 
         .. code-block:: cpp
 
-            py::module m("example", "pybind11 example plugin");
-            py::module m2 = m.def_submodule("sub", "A submodule of 'example'");
-            py::module m3 = m2.def_submodule("subsub", "A submodule of 'example.sub'");
+            py::module_ m("example", "pybind11 example plugin");
+            py::module_ m2 = m.def_submodule("sub", "A submodule of 'example'");
+            py::module_ m3 = m2.def_submodule("subsub", "A submodule of 'example.sub'");
     \endrst */
-    module def_submodule(const char *name, const char *doc = nullptr) {
+    module_ def_submodule(const char *name, const char *doc = nullptr) {
         std::string full_name = std::string(PyModule_GetName(m_ptr))
             + std::string(".") + std::string(name);
-        auto result = reinterpret_borrow<module>(PyImport_AddModule(full_name.c_str()));
+        auto result = reinterpret_borrow<module_>(PyImport_AddModule(full_name.c_str()));
         if (doc && options::show_user_defined_docstrings())
             result.attr("__doc__") = pybind11::str(doc);
         attr(name) = result;
@@ -759,41 +938,104 @@ class module : public object {
     }
 
     /// Import and return a module or throws `error_already_set`.
-    static module import(const char *name) {
+    static module_ import(const char *name) {
         PyObject *obj = PyImport_ImportModule(name);
         if (!obj)
             throw error_already_set();
-        return reinterpret_steal<module>(obj);
+        return reinterpret_steal<module_>(obj);
+    }
+
+    /// Reload the module or throws `error_already_set`.
+    void reload() {
+        PyObject *obj = PyImport_ReloadModule(ptr());
+        if (!obj)
+            throw error_already_set();
+        *this = reinterpret_steal<module_>(obj);
     }
 
-    // Adds an object to the module using the given name.  Throws if an object with the given name
-    // already exists.
-    //
-    // overwrite should almost always be false: attempting to overwrite objects that pybind11 has
-    // established will, in most cases, break things.
-    PYBIND11_NOINLINE void add_object(const char *name, object &obj, bool overwrite = false) {
+    /** \rst
+        Adds an object to the module using the given name.  Throws if an object with the given name
+        already exists.
+
+        ``overwrite`` should almost always be false: attempting to overwrite objects that pybind11 has
+        established will, in most cases, break things.
+    \endrst */
+    PYBIND11_NOINLINE void add_object(const char *name, handle obj, bool overwrite = false) {
         if (!overwrite && hasattr(*this, name))
             pybind11_fail("Error during initialization: multiple incompatible definitions with name \"" +
                     std::string(name) + "\"");
 
-        obj.inc_ref(); // PyModule_AddObject() steals a reference
-        PyModule_AddObject(ptr(), name, obj.ptr());
+        PyModule_AddObject(ptr(), name, obj.inc_ref().ptr() /* steals a reference */);
+    }
+
+#if PY_MAJOR_VERSION >= 3
+    using module_def = PyModuleDef;
+#else
+    struct module_def {};
+#endif
+
+    /** \rst
+        Create a new top-level module that can be used as the main module of a C extension.
+
+        For Python 3, ``def`` should point to a staticly allocated module_def.
+        For Python 2, ``def`` can be a nullptr and is completely ignored.
+    \endrst */
+    static module_ create_extension_module(const char *name, const char *doc, module_def *def) {
+#if PY_MAJOR_VERSION >= 3
+        // module_def is PyModuleDef
+        def = new (def) PyModuleDef {  // Placement new (not an allocation).
+            /* m_base */     PyModuleDef_HEAD_INIT,
+            /* m_name */     name,
+            /* m_doc */      options::show_user_defined_docstrings() ? doc : nullptr,
+            /* m_size */     -1,
+            /* m_methods */  nullptr,
+            /* m_slots */    nullptr,
+            /* m_traverse */ nullptr,
+            /* m_clear */    nullptr,
+            /* m_free */     nullptr
+        };
+        auto m = PyModule_Create(def);
+#else
+        // Ignore module_def *def; only necessary for Python 3
+        (void) def;
+        auto m = Py_InitModule3(name, nullptr, options::show_user_defined_docstrings() ? doc : nullptr);
+#endif
+        if (m == nullptr) {
+            if (PyErr_Occurred())
+                throw error_already_set();
+            pybind11_fail("Internal error in module_::create_extension_module()");
+        }
+        // TODO: Sould be reinterpret_steal for Python 3, but Python also steals it again when returned from PyInit_...
+        //       For Python 2, reinterpret_borrow is correct.
+        return reinterpret_borrow<module_>(m);
     }
 };
 
-NAMESPACE_BEGIN(detail)
+// When inside a namespace (or anywhere as long as it's not the first item on a line),
+// C++20 allows "module" to be used. This is provided for backward compatibility, and for
+// simplicity, if someone wants to use py::module for example, that is perfectly safe.
+using module = module_;
+
+/// \ingroup python_builtins
+/// Return a dictionary representing the global variables in the current execution frame,
+/// or ``__main__.__dict__`` if there is no frame (usually when the interpreter is embedded).
+inline dict globals() {
+    PyObject *p = PyEval_GetGlobals();
+    return reinterpret_borrow<dict>(p ? p : module_::import("__main__").attr("__dict__").ptr());
+}
+
+PYBIND11_NAMESPACE_BEGIN(detail)
 /// Generic support for creating new Python heap types
 class generic_type : public object {
-    template <typename...> friend class class_;
 public:
     PYBIND11_OBJECT_DEFAULT(generic_type, object, PyType_Check)
 protected:
     void initialize(const type_record &rec) {
-        if (rec.scope && hasattr(rec.scope, rec.name))
+        if (rec.scope && hasattr(rec.scope, "__dict__") && rec.scope.attr("__dict__").contains(rec.name))
             pybind11_fail("generic_type: cannot initialize type \"" + std::string(rec.name) +
                           "\": an object with that name is already defined");
 
-        if (get_type_info(*rec.type))
+        if (rec.module_local ? get_local_type_info(*rec.type) : get_global_type_info(*rec.type))
             pybind11_fail("generic_type: type \"" + std::string(rec.name) +
                           "\" is already registered!");
 
@@ -802,20 +1044,41 @@ class generic_type : public object {
         /* Register supplemental type information in C++ dict */
         auto *tinfo = new detail::type_info();
         tinfo->type = (PyTypeObject *) m_ptr;
+        tinfo->cpptype = rec.type;
         tinfo->type_size = rec.type_size;
+        tinfo->type_align = rec.type_align;
         tinfo->operator_new = rec.operator_new;
-        tinfo->init_holder = rec.init_holder;
+        tinfo->holder_size_in_ptrs = size_in_ptrs(rec.holder_size);
+        tinfo->init_instance = rec.init_instance;
         tinfo->dealloc = rec.dealloc;
+        tinfo->simple_type = true;
+        tinfo->simple_ancestors = true;
+        tinfo->default_holder = rec.default_holder;
+        tinfo->module_local = rec.module_local;
 
         auto &internals = get_internals();
         auto tindex = std::type_index(*rec.type);
         tinfo->direct_conversions = &internals.direct_conversions[tindex];
-        tinfo->default_holder = rec.default_holder;
-        internals.registered_types_cpp[tindex] = tinfo;
-        internals.registered_types_py[m_ptr] = tinfo;
+        if (rec.module_local)
+            registered_local_types_cpp()[tindex] = tinfo;
+        else
+            internals.registered_types_cpp[tindex] = tinfo;
+        internals.registered_types_py[(PyTypeObject *) m_ptr] = { tinfo };
 
-        if (rec.bases.size() > 1 || rec.multiple_inheritance)
+        if (rec.bases.size() > 1 || rec.multiple_inheritance) {
             mark_parents_nonsimple(tinfo->type);
+            tinfo->simple_ancestors = false;
+        }
+        else if (rec.bases.size() == 1) {
+            auto parent_tinfo = get_type_info((PyTypeObject *) rec.bases[0].ptr());
+            tinfo->simple_ancestors = parent_tinfo->simple_ancestors;
+        }
+
+        if (rec.module_local) {
+            // Stash the local typeinfo and loader so that external modules can access it.
+            tinfo->module_local_load = &type_caster_generic::local_load;
+            setattr(m_ptr, PYBIND11_MODULE_LOCAL_ID, capsule(tinfo));
+        }
     }
 
     /// Helper function which tags all parents of a type using mult. inheritance
@@ -832,13 +1095,13 @@ class generic_type : public object {
     void install_buffer_funcs(
             buffer_info *(*get_buffer)(PyObject *, void *),
             void *get_buffer_data) {
-        PyHeapTypeObject *type = (PyHeapTypeObject*) m_ptr;
+        auto *type = (PyHeapTypeObject*) m_ptr;
         auto tinfo = detail::get_type_info(&type->ht_type);
 
         if (!type->ht_type.tp_as_buffer)
             pybind11_fail(
                 "To be able to register buffer protocol support for the type '" +
-                std::string(tinfo->type->tp_name) +
+                get_fully_qualified_tp_name(tinfo->type) +
                 "' the associated class<>(..) invocation must "
                 "include the pybind11::buffer_protocol() annotation!");
 
@@ -846,18 +1109,18 @@ class generic_type : public object {
         tinfo->get_buffer_data = get_buffer_data;
     }
 
+    // rec_func must be set for either fget or fset.
     void def_property_static_impl(const char *name,
                                   handle fget, handle fset,
-                                  detail::function_record *rec_fget) {
-        const auto is_static = !(rec_fget->is_method && rec_fget->scope);
-        const auto has_doc = rec_fget->doc && pybind11::options::show_user_defined_docstrings();
-
+                                  detail::function_record *rec_func) {
+        const auto is_static = rec_func && !(rec_func->is_method && rec_func->scope);
+        const auto has_doc = rec_func && rec_func->doc && pybind11::options::show_user_defined_docstrings();
         auto property = handle((PyObject *) (is_static ? get_internals().static_property_type
                                                        : &PyProperty_Type));
         attr(name) = property(fget.ptr() ? fget : none(),
                               fset.ptr() ? fset : none(),
                               /*deleter*/none(),
-                              pybind11::str(has_doc ? rec_fget->doc : ""));
+                              pybind11::str(has_doc ? rec_func->doc : ""));
     }
 };
 
@@ -867,33 +1130,86 @@ void set_operator_new(type_record *r) { r->operator_new = &T::operator new; }
 
 template <typename> void set_operator_new(...) { }
 
+template <typename T, typename SFINAE = void> struct has_operator_delete : std::false_type { };
+template <typename T> struct has_operator_delete<T, void_t<decltype(static_cast<void (*)(void *)>(T::operator delete))>>
+    : std::true_type { };
+template <typename T, typename SFINAE = void> struct has_operator_delete_size : std::false_type { };
+template <typename T> struct has_operator_delete_size<T, void_t<decltype(static_cast<void (*)(void *, size_t)>(T::operator delete))>>
+    : std::true_type { };
 /// Call class-specific delete if it exists or global otherwise. Can also be an overload set.
-template <typename T, typename = void_t<decltype(static_cast<void (*)(void *)>(T::operator delete))>>
-void call_operator_delete(T *p) { T::operator delete(p); }
+template <typename T, enable_if_t<has_operator_delete<T>::value, int> = 0>
+void call_operator_delete(T *p, size_t, size_t) { T::operator delete(p); }
+template <typename T, enable_if_t<!has_operator_delete<T>::value && has_operator_delete_size<T>::value, int> = 0>
+void call_operator_delete(T *p, size_t s, size_t) { T::operator delete(p, s); }
+
+inline void call_operator_delete(void *p, size_t s, size_t a) {
+    (void)s; (void)a;
+    #if defined(__cpp_aligned_new) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
+        if (a > __STDCPP_DEFAULT_NEW_ALIGNMENT__) {
+            #ifdef __cpp_sized_deallocation
+                ::operator delete(p, s, std::align_val_t(a));
+            #else
+                ::operator delete(p, std::align_val_t(a));
+            #endif
+            return;
+        }
+    #endif
+    #ifdef __cpp_sized_deallocation
+        ::operator delete(p, s);
+    #else
+        ::operator delete(p);
+    #endif
+}
+
+inline void add_class_method(object& cls, const char *name_, const cpp_function &cf) {
+    cls.attr(cf.name()) = cf;
+    if (strcmp(name_, "__eq__") == 0 && !cls.attr("__dict__").contains("__hash__")) {
+      cls.attr("__hash__") = none();
+    }
+}
+
+PYBIND11_NAMESPACE_END(detail)
 
-inline void call_operator_delete(void *p) { ::operator delete(p); }
+/// Given a pointer to a member function, cast it to its `Derived` version.
+/// Forward everything else unchanged.
+template <typename /*Derived*/, typename F>
+auto method_adaptor(F &&f) -> decltype(std::forward<F>(f)) { return std::forward<F>(f); }
 
-NAMESPACE_END(detail)
+template <typename Derived, typename Return, typename Class, typename... Args>
+auto method_adaptor(Return (Class::*pmf)(Args...)) -> Return (Derived::*)(Args...) {
+    static_assert(detail::is_accessible_base_of<Class, Derived>::value,
+        "Cannot bind an inaccessible base class method; use a lambda definition instead");
+    return pmf;
+}
+
+template <typename Derived, typename Return, typename Class, typename... Args>
+auto method_adaptor(Return (Class::*pmf)(Args...) const) -> Return (Derived::*)(Args...) const {
+    static_assert(detail::is_accessible_base_of<Class, Derived>::value,
+        "Cannot bind an inaccessible base class method; use a lambda definition instead");
+    return pmf;
+}
 
 template <typename type_, typename... options>
 class class_ : public detail::generic_type {
     template <typename T> using is_holder = detail::is_holder_type<type_, T>;
-    template <typename T> using is_subtype = detail::bool_constant<std::is_base_of<type_, T>::value && !std::is_same<T, type_>::value>;
-    template <typename T> using is_base = detail::bool_constant<std::is_base_of<T, type_>::value && !std::is_same<T, type_>::value>;
+    template <typename T> using is_subtype = detail::is_strict_base_of<type_, T>;
+    template <typename T> using is_base = detail::is_strict_base_of<T, type_>;
     // struct instead of using here to help MSVC:
     template <typename T> struct is_valid_class_option :
         detail::any_of<is_holder<T>, is_subtype<T>, is_base<T>> {};
 
 public:
     using type = type_;
-    using type_alias = detail::first_of_t<is_subtype, void, options...>;
+    using type_alias = detail::exactly_one_t<is_subtype, void, options...>;
     constexpr static bool has_alias = !std::is_void<type_alias>::value;
-    using holder_type = detail::first_of_t<is_holder, std::unique_ptr<type>, options...>;
-    using instance_type = detail::instance<type, holder_type>;
+    using holder_type = detail::exactly_one_t<is_holder, std::unique_ptr<type>, options...>;
 
     static_assert(detail::all_of<is_valid_class_option<options>...>::value,
             "Unknown/invalid class_ template parameters provided");
 
+    static_assert(!has_alias || std::is_polymorphic<type>::value,
+            "Cannot use an alias class with a non-polymorphic type");
+
     PYBIND11_OBJECT(class_, generic_type, PyType_Check)
 
     template <typename... Extra>
@@ -913,16 +1229,16 @@ class class_ : public detail::generic_type {
         record.name = name;
         record.type = &typeid(type);
         record.type_size = sizeof(conditional_t<has_alias, type_alias, type>);
-        record.instance_size = sizeof(instance_type);
-        record.init_holder = init_holder;
+        record.type_align = alignof(conditional_t<has_alias, type_alias, type>&);
+        record.holder_size = sizeof(holder_type);
+        record.init_instance = init_instance;
         record.dealloc = dealloc;
-        record.default_holder = std::is_same<holder_type, std::unique_ptr<type>>::value;
+        record.default_holder = detail::is_instantiation<std::unique_ptr, holder_type>::value;
 
         set_operator_new<type>(&record);
 
         /* Register base classes specified via template arguments to class_, if any */
-        bool unused[] = { (add_base<options>(record), false)..., false };
-        (void) unused;
+        PYBIND11_EXPAND_SIDE_EFFECTS(add_base<options>(record));
 
         /* Process optional arguments, if any */
         process_attributes<Extra...>::init(extra..., &record);
@@ -930,14 +1246,14 @@ class class_ : public detail::generic_type {
         generic_type::initialize(record);
 
         if (has_alias) {
-            auto &instances = get_internals().registered_types_cpp;
+            auto &instances = record.module_local ? registered_local_types_cpp() : get_internals().registered_types_cpp;
             instances[std::type_index(typeid(type_alias))] = instances[std::type_index(typeid(type))];
         }
     }
 
     template <typename Base, detail::enable_if_t<is_base<Base>::value, int> = 0>
     static void add_base(detail::type_record &rec) {
-        rec.add_base(&typeid(Base), [](void *src) -> void * {
+        rec.add_base(typeid(Base), [](void *src) -> void * {
             return static_cast<Base *>(reinterpret_cast<type *>(src));
         });
     }
@@ -947,9 +1263,9 @@ class class_ : public detail::generic_type {
 
     template <typename Func, typename... Extra>
     class_ &def(const char *name_, Func&& f, const Extra&... extra) {
-        cpp_function cf(std::forward<Func>(f), name(name_), is_method(*this),
+        cpp_function cf(method_adaptor<type>(std::forward<Func>(f)), name(name_), is_method(*this),
                         sibling(getattr(*this, name_, none())), extra...);
-        attr(cf.name()) = cf;
+        add_class_method(*this, name_, cf);
         return *this;
     }
 
@@ -959,7 +1275,7 @@ class class_ : public detail::generic_type {
                 "def_static(...) called with a non-static member function pointer");
         cpp_function cf(std::forward<Func>(f), name(name_), scope(*this),
                         sibling(getattr(*this, name_, none())), extra...);
-        attr(cf.name()) = cf;
+        attr(cf.name()) = staticmethod(cf);
         return *this;
     }
 
@@ -976,40 +1292,69 @@ class class_ : public detail::generic_type {
     }
 
     template <typename... Args, typename... Extra>
-    class_ &def(const detail::init<Args...> &init, const Extra&... extra) {
+    class_ &def(const detail::initimpl::constructor<Args...> &init, const Extra&... extra) {
         init.execute(*this, extra...);
         return *this;
     }
 
     template <typename... Args, typename... Extra>
-    class_ &def(const detail::init_alias<Args...> &init, const Extra&... extra) {
+    class_ &def(const detail::initimpl::alias_constructor<Args...> &init, const Extra&... extra) {
         init.execute(*this, extra...);
         return *this;
     }
 
-    template <typename Func> class_& def_buffer(Func &&func) {
+    template <typename... Args, typename... Extra>
+    class_ &def(detail::initimpl::factory<Args...> &&init, const Extra&... extra) {
+        std::move(init).execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename... Args, typename... Extra>
+    class_ &def(detail::initimpl::pickle_factory<Args...> &&pf, const Extra &...extra) {
+        std::move(pf).execute(*this, extra...);
+        return *this;
+    }
+
+    template <typename Func>
+    class_& def_buffer(Func &&func) {
         struct capture { Func func; };
-        capture *ptr = new capture { std::forward<Func>(func) };
+        auto *ptr = new capture { std::forward<Func>(func) };
         install_buffer_funcs([](PyObject *obj, void *ptr) -> buffer_info* {
             detail::make_caster<type> caster;
             if (!caster.load(obj, false))
                 return nullptr;
             return new buffer_info(((capture *) ptr)->func(caster));
         }, ptr);
+        weakref(m_ptr, cpp_function([ptr](handle wr) {
+            delete ptr;
+            wr.dec_ref();
+        })).release();
         return *this;
     }
 
+    template <typename Return, typename Class, typename... Args>
+    class_ &def_buffer(Return (Class::*func)(Args...)) {
+        return def_buffer([func] (type &obj) { return (obj.*func)(); });
+    }
+
+    template <typename Return, typename Class, typename... Args>
+    class_ &def_buffer(Return (Class::*func)(Args...) const) {
+        return def_buffer([func] (const type &obj) { return (obj.*func)(); });
+    }
+
     template <typename C, typename D, typename... Extra>
     class_ &def_readwrite(const char *name, D C::*pm, const Extra&... extra) {
-        cpp_function fget([pm](const C &c) -> const D &{ return c.*pm; }, is_method(*this)),
-                     fset([pm](C &c, const D &value) { c.*pm = value; }, is_method(*this));
+        static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value, "def_readwrite() requires a class member (or base class member)");
+        cpp_function fget([pm](const type &c) -> const D &{ return c.*pm; }, is_method(*this)),
+                     fset([pm](type &c, const D &value) { c.*pm = value; }, is_method(*this));
         def_property(name, fget, fset, return_value_policy::reference_internal, extra...);
         return *this;
     }
 
     template <typename C, typename D, typename... Extra>
     class_ &def_readonly(const char *name, const D C::*pm, const Extra& ...extra) {
-        cpp_function fget([pm](const C &c) -> const D &{ return c.*pm; }, is_method(*this));
+        static_assert(std::is_same<C, type>::value || std::is_base_of<C, type>::value, "def_readonly() requires a class member (or base class member)");
+        cpp_function fget([pm](const type &c) -> const D &{ return c.*pm; }, is_method(*this));
         def_property_readonly(name, fget, return_value_policy::reference_internal, extra...);
         return *this;
     }
@@ -1032,13 +1377,14 @@ class class_ : public detail::generic_type {
     /// Uses return_value_policy::reference_internal by default
     template <typename Getter, typename... Extra>
     class_ &def_property_readonly(const char *name, const Getter &fget, const Extra& ...extra) {
-        return def_property_readonly(name, cpp_function(fget), return_value_policy::reference_internal, extra...);
+        return def_property_readonly(name, cpp_function(method_adaptor<type>(fget)),
+                                     return_value_policy::reference_internal, extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property_readonly(const char *name, const cpp_function &fget, const Extra& ...extra) {
-        return def_property(name, fget, cpp_function(), extra...);
+        return def_property(name, fget, nullptr, extra...);
     }
 
     /// Uses return_value_policy::reference by default
@@ -1050,13 +1396,18 @@ class class_ : public detail::generic_type {
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property_readonly_static(const char *name, const cpp_function &fget, const Extra& ...extra) {
-        return def_property_static(name, fget, cpp_function(), extra...);
+        return def_property_static(name, fget, nullptr, extra...);
     }
 
     /// Uses return_value_policy::reference_internal by default
+    template <typename Getter, typename Setter, typename... Extra>
+    class_ &def_property(const char *name, const Getter &fget, const Setter &fset, const Extra& ...extra) {
+        return def_property(name, fget, cpp_function(method_adaptor<type>(fset)), extra...);
+    }
     template <typename Getter, typename... Extra>
     class_ &def_property(const char *name, const Getter &fget, const cpp_function &fset, const Extra& ...extra) {
-        return def_property(name, cpp_function(fget), fset, return_value_policy::reference_internal, extra...);
+        return def_property(name, cpp_function(method_adaptor<type>(fget)), fset,
+                            return_value_policy::reference_internal, extra...);
     }
 
     /// Uses cpp_function's return_value_policy by default
@@ -1074,73 +1425,106 @@ class class_ : public detail::generic_type {
     /// Uses cpp_function's return_value_policy by default
     template <typename... Extra>
     class_ &def_property_static(const char *name, const cpp_function &fget, const cpp_function &fset, const Extra& ...extra) {
+        static_assert( 0 == detail::constexpr_sum(std::is_base_of<arg, Extra>::value...),
+                      "Argument annotations are not allowed for properties");
         auto rec_fget = get_function_record(fget), rec_fset = get_function_record(fset);
-        char *doc_prev = rec_fget->doc; /* 'extra' field may include a property-specific documentation string */
-        detail::process_attributes<Extra...>::init(extra..., rec_fget);
-        if (rec_fget->doc && rec_fget->doc != doc_prev) {
-            free(doc_prev);
-            rec_fget->doc = strdup(rec_fget->doc);
+        auto *rec_active = rec_fget;
+        if (rec_fget) {
+           char *doc_prev = rec_fget->doc; /* 'extra' field may include a property-specific documentation string */
+           detail::process_attributes<Extra...>::init(extra..., rec_fget);
+           if (rec_fget->doc && rec_fget->doc != doc_prev) {
+              free(doc_prev);
+              rec_fget->doc = strdup(rec_fget->doc);
+           }
         }
         if (rec_fset) {
-            doc_prev = rec_fset->doc;
+            char *doc_prev = rec_fset->doc;
             detail::process_attributes<Extra...>::init(extra..., rec_fset);
             if (rec_fset->doc && rec_fset->doc != doc_prev) {
                 free(doc_prev);
                 rec_fset->doc = strdup(rec_fset->doc);
             }
+            if (! rec_active) rec_active = rec_fset;
         }
-        def_property_static_impl(name, fget, fset, rec_fget);
+        def_property_static_impl(name, fget, fset, rec_active);
         return *this;
     }
 
 private:
     /// Initialize holder object, variant 1: object derives from enable_shared_from_this
     template <typename T>
-    static void init_holder_helper(instance_type *inst, const holder_type * /* unused */, const std::enable_shared_from_this<T> * /* dummy */) {
+    static void init_holder(detail::instance *inst, detail::value_and_holder &v_h,
+            const holder_type * /* unused */, const std::enable_shared_from_this<T> * /* dummy */) {
         try {
-            new (&inst->holder) holder_type(std::static_pointer_cast<typename holder_type::element_type>(inst->value->shared_from_this()));
-            inst->holder_constructed = true;
-        } catch (const std::bad_weak_ptr &) {
-            if (inst->owned) {
-                new (&inst->holder) holder_type(inst->value);
-                inst->holder_constructed = true;
+            auto sh = std::dynamic_pointer_cast<typename holder_type::element_type>(
+                    v_h.value_ptr<type>()->shared_from_this());
+            if (sh) {
+                new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(sh));
+                v_h.set_holder_constructed();
             }
+        } catch (const std::bad_weak_ptr &) {}
+
+        if (!v_h.holder_constructed() && inst->owned) {
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
+            v_h.set_holder_constructed();
         }
     }
 
-    static void init_holder_from_existing(instance_type *inst, const holder_type *holder_ptr,
-                                          std::true_type /*is_copy_constructible*/) {
-        new (&inst->holder) holder_type(*holder_ptr);
+    static void init_holder_from_existing(const detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, std::true_type /*is_copy_constructible*/) {
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(*reinterpret_cast<const holder_type *>(holder_ptr));
     }
 
-    static void init_holder_from_existing(instance_type *inst, const holder_type *holder_ptr,
-                                          std::false_type /*is_copy_constructible*/) {
-        new (&inst->holder) holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
+    static void init_holder_from_existing(const detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, std::false_type /*is_copy_constructible*/) {
+        new (std::addressof(v_h.holder<holder_type>())) holder_type(std::move(*const_cast<holder_type *>(holder_ptr)));
     }
 
     /// Initialize holder object, variant 2: try to construct from existing holder object, if possible
-    static void init_holder_helper(instance_type *inst, const holder_type *holder_ptr, const void * /* dummy */) {
+    static void init_holder(detail::instance *inst, detail::value_and_holder &v_h,
+            const holder_type *holder_ptr, const void * /* dummy -- not enable_shared_from_this<T>) */) {
         if (holder_ptr) {
-            init_holder_from_existing(inst, holder_ptr, std::is_copy_constructible<holder_type>());
-            inst->holder_constructed = true;
+            init_holder_from_existing(v_h, holder_ptr, std::is_copy_constructible<holder_type>());
+            v_h.set_holder_constructed();
         } else if (inst->owned || detail::always_construct_holder<holder_type>::value) {
-            new (&inst->holder) holder_type(inst->value);
-            inst->holder_constructed = true;
+            new (std::addressof(v_h.holder<holder_type>())) holder_type(v_h.value_ptr<type>());
+            v_h.set_holder_constructed();
         }
     }
 
-    /// Initialize holder object of an instance, possibly given a pointer to an existing holder
-    static void init_holder(PyObject *inst_, const void *holder_ptr) {
-        auto inst = (instance_type *) inst_;
-        init_holder_helper(inst, (const holder_type *) holder_ptr, inst->value);
-    }
-
-    static void dealloc(PyObject *inst_) {
-        instance_type *inst = (instance_type *) inst_;
-        if (inst->holder_constructed)
-            inst->holder.~holder_type();
-        else if (inst->owned)
-            detail::call_operator_delete(inst->value);
+    /// Performs instance initialization including constructing a holder and registering the known
+    /// instance.  Should be called as soon as the `type` value_ptr is set for an instance.  Takes an
+    /// optional pointer to an existing holder to use; if not specified and the instance is
+    /// `.owned`, a new holder will be constructed to manage the value pointer.
+    static void init_instance(detail::instance *inst, const void *holder_ptr) {
+        auto v_h = inst->get_value_and_holder(detail::get_type_info(typeid(type)));
+        if (!v_h.instance_registered()) {
+            register_instance(inst, v_h.value_ptr(), v_h.type);
+            v_h.set_instance_registered();
+        }
+        init_holder(inst, v_h, (const holder_type *) holder_ptr, v_h.value_ptr<type>());
+    }
+
+    /// Deallocates an instance; via holder, if constructed; otherwise via operator delete.
+    static void dealloc(detail::value_and_holder &v_h) {
+        // We could be deallocating because we are cleaning up after a Python exception.
+        // If so, the Python error indicator will be set. We need to clear that before
+        // running the destructor, in case the destructor code calls more Python.
+        // If we don't, the Python API will exit with an exception, and pybind11 will
+        // throw error_already_set from the C++ destructor which is forbidden and triggers
+        // std::terminate().
+        error_scope scope;
+        if (v_h.holder_constructed()) {
+            v_h.holder<holder_type>().~holder_type();
+            v_h.set_holder_constructed(false);
+        }
+        else {
+            detail::call_operator_delete(v_h.value_ptr<type>(),
+                v_h.type->type_size,
+                v_h.type->type_align
+            );
+        }
+        v_h.value_ptr() = nullptr;
     }
 
     static detail::function_record *get_function_record(handle h) {
@@ -1150,171 +1534,306 @@ class class_ : public detail::generic_type {
     }
 };
 
+/// Binds an existing constructor taking arguments Args...
+template <typename... Args> detail::initimpl::constructor<Args...> init() { return {}; }
+/// Like `init<Args...>()`, but the instance is always constructed through the alias class (even
+/// when not inheriting on the Python side).
+template <typename... Args> detail::initimpl::alias_constructor<Args...> init_alias() { return {}; }
+
+/// Binds a factory function as a constructor
+template <typename Func, typename Ret = detail::initimpl::factory<Func>>
+Ret init(Func &&f) { return {std::forward<Func>(f)}; }
+
+/// Dual-argument factory function: the first function is called when no alias is needed, the second
+/// when an alias is needed (i.e. due to python-side inheritance).  Arguments must be identical.
+template <typename CFunc, typename AFunc, typename Ret = detail::initimpl::factory<CFunc, AFunc>>
+Ret init(CFunc &&c, AFunc &&a) {
+    return {std::forward<CFunc>(c), std::forward<AFunc>(a)};
+}
+
+/// Binds pickling functions `__getstate__` and `__setstate__` and ensures that the type
+/// returned by `__getstate__` is the same as the argument accepted by `__setstate__`.
+template <typename GetState, typename SetState>
+detail::initimpl::pickle_factory<GetState, SetState> pickle(GetState &&g, SetState &&s) {
+    return {std::forward<GetState>(g), std::forward<SetState>(s)};
+}
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+inline str enum_name(handle arg) {
+    dict entries = arg.get_type().attr("__entries");
+    for (auto kv : entries) {
+        if (handle(kv.second[int_(0)]).equal(arg))
+            return pybind11::str(kv.first);
+    }
+    return "???";
+}
+
+struct enum_base {
+    enum_base(handle base, handle parent) : m_base(base), m_parent(parent) { }
+
+    PYBIND11_NOINLINE void init(bool is_arithmetic, bool is_convertible) {
+        m_base.attr("__entries") = dict();
+        auto property = handle((PyObject *) &PyProperty_Type);
+        auto static_property = handle((PyObject *) get_internals().static_property_type);
+
+        m_base.attr("__repr__") = cpp_function(
+            [](object arg) -> str {
+                handle type = type::handle_of(arg);
+                object type_name = type.attr("__name__");
+                return pybind11::str("<{}.{}: {}>").format(type_name, enum_name(arg), int_(arg));
+            }, name("__repr__"), is_method(m_base)
+        );
+
+        m_base.attr("name") = property(cpp_function(&enum_name, name("name"), is_method(m_base)));
+
+        m_base.attr("__str__") = cpp_function(
+            [](handle arg) -> str {
+                object type_name = type::handle_of(arg).attr("__name__");
+                return pybind11::str("{}.{}").format(type_name, enum_name(arg));
+            }, name("name"), is_method(m_base)
+        );
+
+        m_base.attr("__doc__") = static_property(cpp_function(
+            [](handle arg) -> std::string {
+                std::string docstring;
+                dict entries = arg.attr("__entries");
+                if (((PyTypeObject *) arg.ptr())->tp_doc)
+                    docstring += std::string(((PyTypeObject *) arg.ptr())->tp_doc) + "\n\n";
+                docstring += "Members:";
+                for (auto kv : entries) {
+                    auto key = std::string(pybind11::str(kv.first));
+                    auto comment = kv.second[int_(1)];
+                    docstring += "\n\n  " + key;
+                    if (!comment.is_none())
+                        docstring += " : " + (std::string) pybind11::str(comment);
+                }
+                return docstring;
+            }, name("__doc__")
+        ), none(), none(), "");
+
+        m_base.attr("__members__") = static_property(cpp_function(
+            [](handle arg) -> dict {
+                dict entries = arg.attr("__entries"), m;
+                for (auto kv : entries)
+                    m[kv.first] = kv.second[int_(0)];
+                return m;
+            }, name("__members__")), none(), none(), ""
+        );
+
+        #define PYBIND11_ENUM_OP_STRICT(op, expr, strict_behavior)                     \
+            m_base.attr(op) = cpp_function(                                            \
+                [](object a, object b) {                                               \
+                    if (!type::handle_of(a).is(type::handle_of(b)))                    \
+                        strict_behavior;                                               \
+                    return expr;                                                       \
+                },                                                                     \
+                name(op), is_method(m_base), arg("other"))
+
+        #define PYBIND11_ENUM_OP_CONV(op, expr)                                        \
+            m_base.attr(op) = cpp_function(                                            \
+                [](object a_, object b_) {                                             \
+                    int_ a(a_), b(b_);                                                 \
+                    return expr;                                                       \
+                },                                                                     \
+                name(op), is_method(m_base), arg("other"))
+
+        #define PYBIND11_ENUM_OP_CONV_LHS(op, expr)                                    \
+            m_base.attr(op) = cpp_function(                                            \
+                [](object a_, object b) {                                              \
+                    int_ a(a_);                                                        \
+                    return expr;                                                       \
+                },                                                                     \
+                name(op), is_method(m_base), arg("other"))
+
+        if (is_convertible) {
+            PYBIND11_ENUM_OP_CONV_LHS("__eq__", !b.is_none() &&  a.equal(b));
+            PYBIND11_ENUM_OP_CONV_LHS("__ne__",  b.is_none() || !a.equal(b));
+
+            if (is_arithmetic) {
+                PYBIND11_ENUM_OP_CONV("__lt__",   a <  b);
+                PYBIND11_ENUM_OP_CONV("__gt__",   a >  b);
+                PYBIND11_ENUM_OP_CONV("__le__",   a <= b);
+                PYBIND11_ENUM_OP_CONV("__ge__",   a >= b);
+                PYBIND11_ENUM_OP_CONV("__and__",  a &  b);
+                PYBIND11_ENUM_OP_CONV("__rand__", a &  b);
+                PYBIND11_ENUM_OP_CONV("__or__",   a |  b);
+                PYBIND11_ENUM_OP_CONV("__ror__",  a |  b);
+                PYBIND11_ENUM_OP_CONV("__xor__",  a ^  b);
+                PYBIND11_ENUM_OP_CONV("__rxor__", a ^  b);
+                m_base.attr("__invert__") = cpp_function(
+                    [](object arg) { return ~(int_(arg)); }, name("__invert__"), is_method(m_base));
+            }
+        } else {
+            PYBIND11_ENUM_OP_STRICT("__eq__",  int_(a).equal(int_(b)), return false);
+            PYBIND11_ENUM_OP_STRICT("__ne__", !int_(a).equal(int_(b)), return true);
+
+            if (is_arithmetic) {
+                #define PYBIND11_THROW throw type_error("Expected an enumeration of matching type!");
+                PYBIND11_ENUM_OP_STRICT("__lt__", int_(a) <  int_(b), PYBIND11_THROW);
+                PYBIND11_ENUM_OP_STRICT("__gt__", int_(a) >  int_(b), PYBIND11_THROW);
+                PYBIND11_ENUM_OP_STRICT("__le__", int_(a) <= int_(b), PYBIND11_THROW);
+                PYBIND11_ENUM_OP_STRICT("__ge__", int_(a) >= int_(b), PYBIND11_THROW);
+                #undef PYBIND11_THROW
+            }
+        }
+
+        #undef PYBIND11_ENUM_OP_CONV_LHS
+        #undef PYBIND11_ENUM_OP_CONV
+        #undef PYBIND11_ENUM_OP_STRICT
+
+        m_base.attr("__getstate__") = cpp_function(
+            [](object arg) { return int_(arg); }, name("__getstate__"), is_method(m_base));
+
+        m_base.attr("__hash__") = cpp_function(
+            [](object arg) { return int_(arg); }, name("__hash__"), is_method(m_base));
+    }
+
+    PYBIND11_NOINLINE void value(char const* name_, object value, const char *doc = nullptr) {
+        dict entries = m_base.attr("__entries");
+        str name(name_);
+        if (entries.contains(name)) {
+            std::string type_name = (std::string) str(m_base.attr("__name__"));
+            throw value_error(type_name + ": element \"" + std::string(name_) + "\" already exists!");
+        }
+
+        entries[name] = std::make_pair(value, doc);
+        m_base.attr(name) = value;
+    }
+
+    PYBIND11_NOINLINE void export_values() {
+        dict entries = m_base.attr("__entries");
+        for (auto kv : entries)
+            m_parent.attr(kv.first) = kv.second[int_(0)];
+    }
+
+    handle m_base;
+    handle m_parent;
+};
+
+PYBIND11_NAMESPACE_END(detail)
+
 /// Binds C++ enumerations and enumeration classes to Python
 template <typename Type> class enum_ : public class_<Type> {
 public:
-    using class_<Type>::def;
-    using class_<Type>::def_property_readonly_static;
+    using Base = class_<Type>;
+    using Base::def;
+    using Base::attr;
+    using Base::def_property_readonly;
+    using Base::def_property_readonly_static;
     using Scalar = typename std::underlying_type<Type>::type;
-    template <typename T> using arithmetic_tag = std::is_same<T, arithmetic>;
 
     template <typename... Extra>
     enum_(const handle &scope, const char *name, const Extra&... extra)
-      : class_<Type>(scope, name, extra...), m_entries(), m_parent(scope) {
+      : class_<Type>(scope, name, extra...), m_base(*this, scope) {
+        constexpr bool is_arithmetic = detail::any_of<std::is_same<arithmetic, Extra>...>::value;
+        constexpr bool is_convertible = std::is_convertible<Type, Scalar>::value;
+        m_base.init(is_arithmetic, is_convertible);
 
-        constexpr bool is_arithmetic =
-            !std::is_same<detail::first_of_t<arithmetic_tag, void, Extra...>,
-                          void>::value;
-
-        auto m_entries_ptr = m_entries.inc_ref().ptr();
-        def("__repr__", [name, m_entries_ptr](Type value) -> pybind11::str {
-            for (const auto &kv : reinterpret_borrow<dict>(m_entries_ptr)) {
-                if (pybind11::cast<Type>(kv.second) == value)
-                    return pybind11::str("{}.{}").format(name, kv.first);
-            }
-            return pybind11::str("{}.???").format(name);
-        });
-        def_property_readonly_static("__members__", [m_entries_ptr](object /* self */) {
-            dict m;
-            for (const auto &kv : reinterpret_borrow<dict>(m_entries_ptr))
-                m[kv.first] = kv.second;
-            return m;
-        }, return_value_policy::copy);
-        def("__init__", [](Type& value, Scalar i) { value = (Type)i; });
+        def(init([](Scalar i) { return static_cast<Type>(i); }), arg("value"));
         def("__int__", [](Type value) { return (Scalar) value; });
-        def("__eq__", [](const Type &value, Type *value2) { return value2 && value == *value2; });
-        def("__ne__", [](const Type &value, Type *value2) { return !value2 || value != *value2; });
-        if (is_arithmetic) {
-            def("__lt__", [](const Type &value, Type *value2) { return value2 && value < *value2; });
-            def("__gt__", [](const Type &value, Type *value2) { return value2 && value > *value2; });
-            def("__le__", [](const Type &value, Type *value2) { return value2 && value <= *value2; });
-            def("__ge__", [](const Type &value, Type *value2) { return value2 && value >= *value2; });
-        }
-        if (std::is_convertible<Type, Scalar>::value) {
-            // Don't provide comparison with the underlying type if the enum isn't convertible,
-            // i.e. if Type is a scoped enum, mirroring the C++ behaviour.  (NB: we explicitly
-            // convert Type to Scalar below anyway because this needs to compile).
-            def("__eq__", [](const Type &value, Scalar value2) { return (Scalar) value == value2; });
-            def("__ne__", [](const Type &value, Scalar value2) { return (Scalar) value != value2; });
-            if (is_arithmetic) {
-                def("__lt__", [](const Type &value, Scalar value2) { return (Scalar) value < value2; });
-                def("__gt__", [](const Type &value, Scalar value2) { return (Scalar) value > value2; });
-                def("__le__", [](const Type &value, Scalar value2) { return (Scalar) value <= value2; });
-                def("__ge__", [](const Type &value, Scalar value2) { return (Scalar) value >= value2; });
-                def("__invert__", [](const Type &value) { return ~((Scalar) value); });
-                def("__and__", [](const Type &value, Scalar value2) { return (Scalar) value & value2; });
-                def("__or__", [](const Type &value, Scalar value2) { return (Scalar) value | value2; });
-                def("__xor__", [](const Type &value, Scalar value2) { return (Scalar) value ^ value2; });
-                def("__rand__", [](const Type &value, Scalar value2) { return (Scalar) value & value2; });
-                def("__ror__", [](const Type &value, Scalar value2) { return (Scalar) value | value2; });
-                def("__rxor__", [](const Type &value, Scalar value2) { return (Scalar) value ^ value2; });
-                def("__and__", [](const Type &value, const Type &value2) { return (Scalar) value & (Scalar) value2; });
-                def("__or__", [](const Type &value, const Type &value2) { return (Scalar) value | (Scalar) value2; });
-                def("__xor__", [](const Type &value, const Type &value2) { return (Scalar) value ^ (Scalar) value2; });
-            }
-        }
-        def("__hash__", [](const Type &value) { return (Scalar) value; });
-        // Pickling and unpickling -- needed for use with the 'multiprocessing' module
-        def("__getstate__", [](const Type &value) { return pybind11::make_tuple((Scalar) value); });
-        def("__setstate__", [](Type &p, tuple t) { new (&p) Type((Type) t[0].cast<Scalar>()); });
+        #if PY_MAJOR_VERSION < 3
+            def("__long__", [](Type value) { return (Scalar) value; });
+        #endif
+        #if PY_MAJOR_VERSION > 3 || (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 8)
+            def("__index__", [](Type value) { return (Scalar) value; });
+        #endif
+
+        attr("__setstate__") = cpp_function(
+            [](detail::value_and_holder &v_h, Scalar arg) {
+                detail::initimpl::setstate<Base>(v_h, static_cast<Type>(arg),
+                        Py_TYPE(v_h.inst) != v_h.type->type); },
+            detail::is_new_style_constructor(),
+            pybind11::name("__setstate__"), is_method(*this), arg("state"));
     }
 
     /// Export enumeration entries into the parent scope
     enum_& export_values() {
-        for (const auto &kv : m_entries)
-            m_parent.attr(kv.first) = kv.second;
+        m_base.export_values();
         return *this;
     }
 
     /// Add an enumeration entry
-    enum_& value(char const* name, Type value) {
-        auto v = pybind11::cast(value, return_value_policy::copy);
-        this->attr(name) = v;
-        m_entries[pybind11::str(name)] = v;
+    enum_& value(char const* name, Type value, const char *doc = nullptr) {
+        m_base.value(name, pybind11::cast(value, return_value_policy::copy), doc);
         return *this;
     }
 
 private:
-    dict m_entries;
-    handle m_parent;
+    detail::enum_base m_base;
 };
 
-NAMESPACE_BEGIN(detail)
-template <typename... Args> struct init {
-    template <typename Class, typename... Extra, enable_if_t<!Class::has_alias, int> = 0>
-    static void execute(Class &cl, const Extra&... extra) {
-        using Base = typename Class::type;
-        /// Function which calls a specific C++ in-place constructor
-        cl.def("__init__", [](Base *self_, Args... args) { new (self_) Base(args...); }, extra...);
-    }
-
-    template <typename Class, typename... Extra,
-              enable_if_t<Class::has_alias &&
-                          std::is_constructible<typename Class::type, Args...>::value, int> = 0>
-    static void execute(Class &cl, const Extra&... extra) {
-        using Base = typename Class::type;
-        using Alias = typename Class::type_alias;
-        handle cl_type = cl;
-        cl.def("__init__", [cl_type](handle self_, Args... args) {
-                if (self_.get_type() == cl_type)
-                    new (self_.cast<Base *>()) Base(args...);
-                else
-                    new (self_.cast<Alias *>()) Alias(args...);
-            }, extra...);
-    }
-
-    template <typename Class, typename... Extra,
-              enable_if_t<Class::has_alias &&
-                          !std::is_constructible<typename Class::type, Args...>::value, int> = 0>
-    static void execute(Class &cl, const Extra&... extra) {
-        init_alias<Args...>::execute(cl, extra...);
-    }
-};
-template <typename... Args> struct init_alias {
-    template <typename Class, typename... Extra,
-              enable_if_t<Class::has_alias && std::is_constructible<typename Class::type_alias, Args...>::value, int> = 0>
-    static void execute(Class &cl, const Extra&... extra) {
-        using Alias = typename Class::type_alias;
-        cl.def("__init__", [](Alias *self_, Args... args) { new (self_) Alias(args...); }, extra...);
-    }
-};
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 
 inline void keep_alive_impl(handle nurse, handle patient) {
-    /* Clever approach based on weak references taken from Boost.Python */
     if (!nurse || !patient)
         pybind11_fail("Could not activate keep_alive!");
 
     if (patient.is_none() || nurse.is_none())
         return; /* Nothing to keep alive or nothing to be kept alive by */
 
-    cpp_function disable_lifesupport(
-        [patient](handle weakref) { patient.dec_ref(); weakref.dec_ref(); });
+    auto tinfo = all_type_info(Py_TYPE(nurse.ptr()));
+    if (!tinfo.empty()) {
+        /* It's a pybind-registered type, so we can store the patient in the
+         * internal list. */
+        add_patient(nurse.ptr(), patient.ptr());
+    }
+    else {
+        /* Fall back to clever approach based on weak references taken from
+         * Boost.Python. This is not used for pybind-registered types because
+         * the objects can be destroyed out-of-order in a GC pass. */
+        cpp_function disable_lifesupport(
+            [patient](handle weakref) { patient.dec_ref(); weakref.dec_ref(); });
 
-    weakref wr(nurse, disable_lifesupport);
+        weakref wr(nurse, disable_lifesupport);
 
-    patient.inc_ref(); /* reference patient and leak the weak reference */
-    (void) wr.release();
+        patient.inc_ref(); /* reference patient and leak the weak reference */
+        (void) wr.release();
+    }
 }
 
 PYBIND11_NOINLINE inline void keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret) {
-    keep_alive_impl(
-        Nurse   == 0 ? ret : Nurse   <= call.args.size() ? call.args[Nurse   - 1] : handle(),
-        Patient == 0 ? ret : Patient <= call.args.size() ? call.args[Patient - 1] : handle()
-    );
+    auto get_arg = [&](size_t n) {
+        if (n == 0)
+            return ret;
+        else if (n == 1 && call.init_self)
+            return call.init_self;
+        else if (n <= call.args.size())
+            return call.args[n - 1];
+        return handle();
+    };
+
+    keep_alive_impl(get_arg(Nurse), get_arg(Patient));
+}
+
+inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_type_info_get_cache(PyTypeObject *type) {
+    auto res = get_internals().registered_types_py
+#ifdef __cpp_lib_unordered_map_try_emplace
+        .try_emplace(type);
+#else
+        .emplace(type, std::vector<detail::type_info *>());
+#endif
+    if (res.second) {
+        // New cache entry created; set up a weak reference to automatically remove it if the type
+        // gets destroyed:
+        weakref((PyObject *) type, cpp_function([type](handle wr) {
+            get_internals().registered_types_py.erase(type);
+            wr.dec_ref();
+        })).release();
+    }
+
+    return res;
 }
 
 template <typename Iterator, typename Sentinel, bool KeyIterator, return_value_policy Policy>
 struct iterator_state {
     Iterator it;
     Sentinel end;
-    bool first;
+    bool first_or_done;
 };
 
-NAMESPACE_END(detail)
-
-template <typename... Args> detail::init<Args...> init() { return detail::init<Args...>(); }
-template <typename... Args> detail::init_alias<Args...> init_alias() { return detail::init_alias<Args...>(); }
+PYBIND11_NAMESPACE_END(detail)
 
 /// Makes a python iterator from a first and past-the-end C++ InputIterator.
 template <return_value_policy Policy = return_value_policy::reference_internal,
@@ -1323,23 +1842,25 @@ template <return_value_policy Policy = return_value_policy::reference_internal,
           typename ValueType = decltype(*std::declval<Iterator>()),
           typename... Extra>
 iterator make_iterator(Iterator first, Sentinel last, Extra &&... extra) {
-    typedef detail::iterator_state<Iterator, Sentinel, false, Policy> state;
+    using state = detail::iterator_state<Iterator, Sentinel, false, Policy>;
 
     if (!detail::get_type_info(typeid(state), false)) {
-        class_<state>(handle(), "iterator")
+        class_<state>(handle(), "iterator", pybind11::module_local())
             .def("__iter__", [](state &s) -> state& { return s; })
             .def("__next__", [](state &s) -> ValueType {
-                if (!s.first)
+                if (!s.first_or_done)
                     ++s.it;
                 else
-                    s.first = false;
-                if (s.it == s.end)
+                    s.first_or_done = false;
+                if (s.it == s.end) {
+                    s.first_or_done = true;
                     throw stop_iteration();
+                }
                 return *s.it;
             }, std::forward<Extra>(extra)..., Policy);
     }
 
-    return (iterator) cast(state { first, last, true });
+    return cast(state{first, last, true});
 }
 
 /// Makes an python iterator over the keys (`.first`) of a iterator over pairs from a
@@ -1350,23 +1871,25 @@ template <return_value_policy Policy = return_value_policy::reference_internal,
           typename KeyType = decltype((*std::declval<Iterator>()).first),
           typename... Extra>
 iterator make_key_iterator(Iterator first, Sentinel last, Extra &&... extra) {
-    typedef detail::iterator_state<Iterator, Sentinel, true, Policy> state;
+    using state = detail::iterator_state<Iterator, Sentinel, true, Policy>;
 
     if (!detail::get_type_info(typeid(state), false)) {
-        class_<state>(handle(), "iterator")
+        class_<state>(handle(), "iterator", pybind11::module_local())
             .def("__iter__", [](state &s) -> state& { return s; })
             .def("__next__", [](state &s) -> KeyType {
-                if (!s.first)
+                if (!s.first_or_done)
                     ++s.it;
                 else
-                    s.first = false;
-                if (s.it == s.end)
+                    s.first_or_done = false;
+                if (s.it == s.end) {
+                    s.first_or_done = true;
                     throw stop_iteration();
+                }
                 return (*s.it).first;
             }, std::forward<Extra>(extra)..., Policy);
     }
 
-    return (iterator) cast(state { first, last, true });
+    return cast(state{first, last, true});
 }
 
 /// Makes an iterator over values of an stl container or other container supporting
@@ -1384,7 +1907,16 @@ template <return_value_policy Policy = return_value_policy::reference_internal,
 }
 
 template <typename InputType, typename OutputType> void implicitly_convertible() {
+    struct set_flag {
+        bool &flag;
+        set_flag(bool &flag) : flag(flag) { flag = true; }
+        ~set_flag() { flag = false; }
+    };
     auto implicit_caster = [](PyObject *obj, PyTypeObject *type) -> PyObject * {
+        static bool currently_used = false;
+        if (currently_used) // implicit conversions are non-reentrant
+            return nullptr;
+        set_flag flag_helper(currently_used);
         if (!detail::make_caster<InputType>().load(obj, false))
             return nullptr;
         tuple args(1);
@@ -1407,7 +1939,8 @@ void register_exception_translator(ExceptionTranslator&& translator) {
         std::forward<ExceptionTranslator>(translator));
 }
 
-/* Wrapper to generate a new Python exception type.
+/**
+ * Wrapper to generate a new Python exception type.
  *
  * This should only be used with PyErr_SetString for now.
  * It is not (yet) possible to use as a py::base.
@@ -1416,11 +1949,12 @@ void register_exception_translator(ExceptionTranslator&& translator) {
 template <typename type>
 class exception : public object {
 public:
-    exception(handle scope, const char *name, PyObject *base = PyExc_Exception) {
+    exception() = default;
+    exception(handle scope, const char *name, handle base = PyExc_Exception) {
         std::string full_name = scope.attr("__name__").cast<std::string>() +
                                 std::string(".") + name;
-        m_ptr = PyErr_NewException(const_cast<char *>(full_name.c_str()), base, NULL);
-        if (hasattr(scope, name))
+        m_ptr = PyErr_NewException(const_cast<char *>(full_name.c_str()), base.ptr(), NULL);
+        if (hasattr(scope, "__dict__") && scope.attr("__dict__").contains(name))
             pybind11_fail("Error during initialization: multiple incompatible "
                           "definitions with name \"" + std::string(name) + "\"");
         scope.attr(name) = *this;
@@ -1432,7 +1966,16 @@ class exception : public object {
     }
 };
 
-/** Registers a Python exception in `m` of the given `name` and installs an exception translator to
+PYBIND11_NAMESPACE_BEGIN(detail)
+// Returns a reference to a function-local static exception object used in the simple
+// register_exception approach below.  (It would be simpler to have the static local variable
+// directly in register_exception, but that makes clang <3.5 segfault - issue #1349).
+template <typename CppException>
+exception<CppException> &get_exception_object() { static exception<CppException> ex; return ex; }
+PYBIND11_NAMESPACE_END(detail)
+
+/**
+ * Registers a Python exception in `m` of the given `name` and installs an exception translator to
  * translate the C++ exception to the created Python exception using the exceptions what() method.
  * This is intended for simple exception translations; for more complex translation, register the
  * exception object and translator directly.
@@ -1440,20 +1983,22 @@ class exception : public object {
 template <typename CppException>
 exception<CppException> &register_exception(handle scope,
                                             const char *name,
-                                            PyObject *base = PyExc_Exception) {
-    static exception<CppException> ex(scope, name, base);
+                                            handle base = PyExc_Exception) {
+    auto &ex = detail::get_exception_object<CppException>();
+    if (!ex) ex = exception<CppException>(scope, name, base);
+
     register_exception_translator([](std::exception_ptr p) {
         if (!p) return;
         try {
             std::rethrow_exception(p);
         } catch (const CppException &e) {
-            ex(e.what());
+            detail::get_exception_object<CppException>()(e.what());
         }
     });
     return ex;
 }
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 PYBIND11_NOINLINE inline void print(tuple args, dict kwargs) {
     auto strings = tuple(args.size());
     for (size_t i = 0; i < args.size(); ++i) {
@@ -1467,7 +2012,7 @@ PYBIND11_NOINLINE inline void print(tuple args, dict kwargs) {
         file = kwargs["file"].cast<object>();
     } else {
         try {
-            file = module::import("sys").attr("stdout");
+            file = module_::import("sys").attr("stdout");
         } catch (const error_already_set &) {
             /* If print() is called from code that is executed as
                part of garbage collection during interpreter shutdown,
@@ -1484,7 +2029,7 @@ PYBIND11_NOINLINE inline void print(tuple args, dict kwargs) {
     if (kwargs.contains("flush") && kwargs["flush"].cast<bool>())
         file.attr("flush")();
 }
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 template <return_value_policy policy = return_value_policy::automatic_reference, typename... Args>
 void print(Args &&...args) {
@@ -1520,7 +2065,16 @@ class gil_scoped_acquire {
 public:
     PYBIND11_NOINLINE gil_scoped_acquire() {
         auto const &internals = detail::get_internals();
-        tstate = (PyThreadState *) PyThread_get_key_value(internals.tstate);
+        tstate = (PyThreadState *) PYBIND11_TLS_GET_VALUE(internals.tstate);
+
+        if (!tstate) {
+            /* Check if the GIL was acquired using the PyGILState_* API instead (e.g. if
+               calling from a Python thread). Since we use a different key, this ensures
+               we don't create a new thread state and deadlock in PyEval_AcquireThread
+               below. Note we don't save this state with internals.tstate, since we don't
+               create it we would fail to clear it (its reference count should be > 0). */
+            tstate = PyGILState_GetThisThreadState();
+        }
 
         if (!tstate) {
             tstate = PyThreadState_New(internals.istate);
@@ -1529,10 +2083,7 @@ class gil_scoped_acquire {
                     pybind11_fail("scoped_acquire: could not create thread state!");
             #endif
             tstate->gilstate_counter = 0;
-            #if PY_MAJOR_VERSION < 3
-                PyThread_delete_key_value(internals.tstate);
-            #endif
-            PyThread_set_key_value(internals.tstate, tstate);
+            PYBIND11_TLS_REPLACE_VALUE(internals.tstate, tstate);
         } else {
             release = detail::get_thread_state_unchecked() != tstate;
         }
@@ -1571,7 +2122,7 @@ class gil_scoped_acquire {
             #endif
             PyThreadState_Clear(tstate);
             PyThreadState_DeleteCurrent();
-            PyThread_delete_key_value(detail::get_internals().tstate);
+            PYBIND11_TLS_DELETE_VALUE(detail::get_internals().tstate);
             release = false;
         }
     }
@@ -1589,14 +2140,14 @@ class gil_scoped_acquire {
 class gil_scoped_release {
 public:
     explicit gil_scoped_release(bool disassoc = false) : disassoc(disassoc) {
+        // `get_internals()` must be called here unconditionally in order to initialize
+        // `internals.tstate` for subsequent `gil_scoped_acquire` calls. Otherwise, an
+        // initialization race could occur as multiple threads try `gil_scoped_acquire`.
+        const auto &internals = detail::get_internals();
         tstate = PyEval_SaveThread();
         if (disassoc) {
-            auto key = detail::get_internals().tstate;
-            #if PY_MAJOR_VERSION < 3
-                PyThread_delete_key_value(key);
-            #else
-                PyThread_set_key_value(key, nullptr);
-            #endif
+            auto key = internals.tstate;
+            PYBIND11_TLS_DELETE_VALUE(key);
         }
     }
     ~gil_scoped_release() {
@@ -1605,10 +2156,7 @@ class gil_scoped_release {
         PyEval_RestoreThread(tstate);
         if (disassoc) {
             auto key = detail::get_internals().tstate;
-            #if PY_MAJOR_VERSION < 3
-                PyThread_delete_key_value(key);
-            #endif
-            PyThread_set_key_value(key, tstate);
+            PYBIND11_TLS_REPLACE_VALUE(key, tstate);
         }
     }
 private:
@@ -1635,27 +2183,31 @@ class gil_scoped_release { };
 #endif
 
 error_already_set::~error_already_set() {
-    if (value) {
+    if (m_type) {
         gil_scoped_acquire gil;
-        clear();
+        error_scope scope;
+        m_type.release().dec_ref();
+        m_value.release().dec_ref();
+        m_trace.release().dec_ref();
     }
 }
 
-inline function get_type_overload(const void *this_ptr, const detail::type_info *this_type, const char *name)  {
-    handle self = detail::get_object_handle(this_ptr, this_type);
+PYBIND11_NAMESPACE_BEGIN(detail)
+inline function get_type_override(const void *this_ptr, const type_info *this_type, const char *name)  {
+    handle self = get_object_handle(this_ptr, this_type);
     if (!self)
         return function();
-    handle type = self.get_type();
+    handle type = type::handle_of(self);
     auto key = std::make_pair(type.ptr(), name);
 
-    /* Cache functions that aren't overloaded in Python to avoid
+    /* Cache functions that aren't overridden in Python to avoid
        many costly Python dictionary lookups below */
-    auto &cache = detail::get_internals().inactive_overload_cache;
+    auto &cache = get_internals().inactive_override_cache;
     if (cache.find(key) != cache.end())
         return function();
 
-    function overload = getattr(self, name, function());
-    if (overload.is_cpp_function()) {
+    function override = getattr(self, name, function());
+    if (override.is_cpp_function()) {
         cache.insert(key);
         return function();
     }
@@ -1690,52 +2242,137 @@ inline function get_type_overload(const void *this_ptr, const detail::type_info
         Py_file_input, d.ptr(), d.ptr());
     if (result == nullptr)
         throw error_already_set();
-    if ((handle) d["self"] == Py_None)
+    if (d["self"].is_none())
         return function();
     Py_DECREF(result);
 #endif
 
-    return overload;
+    return override;
 }
+PYBIND11_NAMESPACE_END(detail)
+
+/** \rst
+  Try to retrieve a python method by the provided name from the instance pointed to by the this_ptr.
 
-template <class T> function get_overload(const T *this_ptr, const char *name) {
+  :this_ptr: The pointer to the object the overriden method should be retrieved for. This should be
+             the first non-trampoline class encountered in the inheritance chain.
+  :name: The name of the overridden Python method to retrieve.
+  :return: The Python method by this name from the object or an empty function wrapper.
+ \endrst */
+template <class T> function get_override(const T *this_ptr, const char *name) {
     auto tinfo = detail::get_type_info(typeid(T));
-    return tinfo ? get_type_overload(this_ptr, tinfo, name) : function();
+    return tinfo ? detail::get_type_override(this_ptr, tinfo, name) : function();
 }
 
-#define PYBIND11_OVERLOAD_INT(ret_type, cname, name, ...) { \
+#define PYBIND11_OVERRIDE_IMPL(ret_type, cname, name, ...) \
+    do { \
         pybind11::gil_scoped_acquire gil; \
-        pybind11::function overload = pybind11::get_overload(static_cast<const cname *>(this), name); \
-        if (overload) { \
-            auto o = overload(__VA_ARGS__); \
+        pybind11::function override = pybind11::get_override(static_cast<const cname *>(this), name); \
+        if (override) { \
+            auto o = override(__VA_ARGS__); \
             if (pybind11::detail::cast_is_temporary_value_reference<ret_type>::value) { \
-                static pybind11::detail::overload_caster_t<ret_type> caster; \
+                static pybind11::detail::override_caster_t<ret_type> caster; \
                 return pybind11::detail::cast_ref<ret_type>(std::move(o), caster); \
             } \
             else return pybind11::detail::cast_safe<ret_type>(std::move(o)); \
         } \
-    }
+    } while (false)
+
+/** \rst
+    Macro to populate the virtual method in the trampoline class. This macro tries to look up a method named 'fn'
+    from the Python side, deals with the :ref:`gil` and necessary argument conversions to call this method and return
+    the appropriate type. See :ref:`overriding_virtuals` for more information. This macro should be used when the method
+    name in C is not the same as the method name in Python. For example with `__str__`.
+
+    .. code-block:: cpp
+
+      std::string toString() override {
+        PYBIND11_OVERRIDE_NAME(
+            std::string, // Return type (ret_type)
+            Animal,      // Parent class (cname)
+            "__str__",   // Name of method in Python (name)
+            toString,    // Name of function in C++ (fn)
+        );
+      }
+\endrst */
+#define PYBIND11_OVERRIDE_NAME(ret_type, cname, name, fn, ...) \
+    do { \
+        PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__); \
+        return cname::fn(__VA_ARGS__); \
+    } while (false)
+
+/** \rst
+    Macro for pure virtual functions, this function is identical to :c:macro:`PYBIND11_OVERRIDE_NAME`, except that it
+    throws if no override can be found.
+\endrst */
+#define PYBIND11_OVERRIDE_PURE_NAME(ret_type, cname, name, fn, ...) \
+    do { \
+        PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__); \
+        pybind11::pybind11_fail("Tried to call pure virtual function \"" PYBIND11_STRINGIFY(cname) "::" name "\""); \
+    } while (false)
+
+/** \rst
+    Macro to populate the virtual method in the trampoline class. This macro tries to look up the method
+    from the Python side, deals with the :ref:`gil` and necessary argument conversions to call this method and return
+    the appropriate type. This macro should be used if the method name in C and in Python are identical.
+    See :ref:`overriding_virtuals` for more information.
+
+    .. code-block:: cpp
+
+      class PyAnimal : public Animal {
+      public:
+          // Inherit the constructors
+          using Animal::Animal;
+
+          // Trampoline (need one for each virtual function)
+          std::string go(int n_times) override {
+              PYBIND11_OVERRIDE_PURE(
+                  std::string, // Return type (ret_type)
+                  Animal,      // Parent class (cname)
+                  go,          // Name of function in C++ (must match Python name) (fn)
+                  n_times      // Argument(s) (...)
+              );
+          }
+      };
+\endrst */
+#define PYBIND11_OVERRIDE(ret_type, cname, fn, ...) \
+    PYBIND11_OVERRIDE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), #fn, fn, __VA_ARGS__)
+
+/** \rst
+    Macro for pure virtual functions, this function is identical to :c:macro:`PYBIND11_OVERRIDE`, except that it throws
+    if no override can be found.
+\endrst */
+#define PYBIND11_OVERRIDE_PURE(ret_type, cname, fn, ...) \
+    PYBIND11_OVERRIDE_PURE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), #fn, fn, __VA_ARGS__)
+
+
+// Deprecated versions
+
+PYBIND11_DEPRECATED("get_type_overload has been deprecated")
+inline function get_type_overload(const void *this_ptr, const detail::type_info *this_type, const char *name) {
+    return detail::get_type_override(this_ptr, this_type, name);
+}
 
-#define PYBIND11_OVERLOAD_NAME(ret_type, cname, name, fn, ...) \
-    PYBIND11_OVERLOAD_INT(ret_type, cname, name, __VA_ARGS__) \
-    return cname::fn(__VA_ARGS__)
+template <class T>
+inline function get_overload(const T *this_ptr, const char *name) {
+    return get_override(this_ptr, name);
+}
 
+#define PYBIND11_OVERLOAD_INT(ret_type, cname, name, ...) \
+    PYBIND11_OVERRIDE_IMPL(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, __VA_ARGS__)
+#define PYBIND11_OVERLOAD_NAME(ret_type, cname, name, fn, ...) \
+    PYBIND11_OVERRIDE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, fn, __VA_ARGS__)
 #define PYBIND11_OVERLOAD_PURE_NAME(ret_type, cname, name, fn, ...) \
-    PYBIND11_OVERLOAD_INT(ret_type, cname, name, __VA_ARGS__) \
-    pybind11::pybind11_fail("Tried to call pure virtual function \"" #cname "::" name "\"");
-
+    PYBIND11_OVERRIDE_PURE_NAME(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), name, fn, __VA_ARGS__);
 #define PYBIND11_OVERLOAD(ret_type, cname, fn, ...) \
-    PYBIND11_OVERLOAD_NAME(ret_type, cname, #fn, fn, __VA_ARGS__)
-
+    PYBIND11_OVERRIDE(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), fn, __VA_ARGS__)
 #define PYBIND11_OVERLOAD_PURE(ret_type, cname, fn, ...) \
-    PYBIND11_OVERLOAD_PURE_NAME(ret_type, cname, #fn, fn, __VA_ARGS__)
+    PYBIND11_OVERRIDE_PURE(PYBIND11_TYPE(ret_type), PYBIND11_TYPE(cname), fn, __VA_ARGS__);
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
 #  pragma warning(pop)
-#elif defined(__INTEL_COMPILER)
-/* Leave ignored warnings on */
 #elif defined(__GNUG__) && !defined(__clang__)
 #  pragma GCC diagnostic pop
 #endif
diff --git a/libs/pybind/pybind11/pytypes.h b/libs/pybind/pybind11/pytypes.h
index 900c57564e..1010ad713c 100644
--- a/libs/pybind/pybind11/pytypes.h
+++ b/libs/pybind/pybind11/pytypes.h
@@ -1,5 +1,5 @@
 /*
-    pybind11/typeid.h: Convenience wrapper classes for basic Python types
+    pybind11/pytypes.h: Convenience wrapper classes for basic Python types
 
     Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
 
@@ -9,18 +9,20 @@
 
 #pragma once
 
-#include "common.h"
+#include "detail/common.h"
+#include "buffer_info.h"
 #include <utility>
 #include <type_traits>
 
-NAMESPACE_BEGIN(pybind11)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
 
 /* A few forward declarations */
 class handle; class object;
 class str; class iterator;
+class type;
 struct arg; struct arg_v;
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 class args_proxy;
 inline bool isinstance_generic(handle obj, const std::type_info &tp);
 
@@ -33,7 +35,7 @@ namespace accessor_policies {
     struct sequence_item;
     struct list_item;
     struct tuple_item;
-}
+} // namespace accessor_policies
 using obj_attr_accessor = accessor<accessor_policies::obj_attr>;
 using str_attr_accessor = accessor<accessor_policies::str_attr>;
 using item_accessor = accessor<accessor_policies::generic_item>;
@@ -43,7 +45,7 @@ using tuple_accessor = accessor<accessor_policies::tuple_item>;
 
 /// Tag and check to identify a class which implements the Python object API
 class pyobject_tag { };
-template <typename T> using is_pyobject = std::is_base_of<pyobject_tag, typename std::remove_reference<T>::type>;
+template <typename T> using is_pyobject = std::is_base_of<pyobject_tag, remove_reference_t<T>>;
 
 /** \rst
     A mixin class which adds common functions to `handle`, `object` and various accessors.
@@ -109,18 +111,56 @@ class object_api : public pyobject_tag {
     PYBIND11_DEPRECATED("call(...) was deprecated in favor of operator()(...)")
         object call(Args&&... args) const;
 
+    /// Equivalent to ``obj is other`` in Python.
+    bool is(object_api const& other) const { return derived().ptr() == other.derived().ptr(); }
     /// Equivalent to ``obj is None`` in Python.
     bool is_none() const { return derived().ptr() == Py_None; }
+    /// Equivalent to obj == other in Python
+    bool equal(object_api const &other) const      { return rich_compare(other, Py_EQ); }
+    bool not_equal(object_api const &other) const  { return rich_compare(other, Py_NE); }
+    bool operator<(object_api const &other) const  { return rich_compare(other, Py_LT); }
+    bool operator<=(object_api const &other) const { return rich_compare(other, Py_LE); }
+    bool operator>(object_api const &other) const  { return rich_compare(other, Py_GT); }
+    bool operator>=(object_api const &other) const { return rich_compare(other, Py_GE); }
+
+    object operator-() const;
+    object operator~() const;
+    object operator+(object_api const &other) const;
+    object operator+=(object_api const &other) const;
+    object operator-(object_api const &other) const;
+    object operator-=(object_api const &other) const;
+    object operator*(object_api const &other) const;
+    object operator*=(object_api const &other) const;
+    object operator/(object_api const &other) const;
+    object operator/=(object_api const &other) const;
+    object operator|(object_api const &other) const;
+    object operator|=(object_api const &other) const;
+    object operator&(object_api const &other) const;
+    object operator&=(object_api const &other) const;
+    object operator^(object_api const &other) const;
+    object operator^=(object_api const &other) const;
+    object operator<<(object_api const &other) const;
+    object operator<<=(object_api const &other) const;
+    object operator>>(object_api const &other) const;
+    object operator>>=(object_api const &other) const;
+
     PYBIND11_DEPRECATED("Use py::str(obj) instead")
     pybind11::str str() const;
 
+    /// Get or set the object's docstring, i.e. ``obj.__doc__``.
+    str_attr_accessor doc() const;
+
     /// Return the object's current reference count
     int ref_count() const { return static_cast<int>(Py_REFCNT(derived().ptr())); }
-    /// Return a handle to the Python type object underlying the instance
+
+    // TODO PYBIND11_DEPRECATED("Call py::type::handle_of(h) or py::type::of(h) instead of h.get_type()")
     handle get_type() const;
+
+private:
+    bool rich_compare(object_api const &other, int value) const;
 };
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 /** \rst
     Holds a reference to a Python object (no reference counting)
@@ -166,10 +206,12 @@ class handle : public detail::object_api<handle> {
     /// Return ``true`` when the `handle` wraps a valid Python object
     explicit operator bool() const { return m_ptr != nullptr; }
     /** \rst
-        Check that the underlying pointers are the same.
+        Deprecated: Check that the underlying pointers are the same.
         Equivalent to ``obj1 is obj2`` in Python.
     \endrst */
+    PYBIND11_DEPRECATED("Use obj1.is(obj2) instead")
     bool operator==(const handle &h) const { return m_ptr == h.m_ptr; }
+    PYBIND11_DEPRECATED("Use !obj1.is(obj2) instead")
     bool operator!=(const handle &h) const { return m_ptr != h.m_ptr; }
     PYBIND11_DEPRECATED("Use handle::operator bool() instead")
     bool check() const { return m_ptr != nullptr; }
@@ -200,7 +242,7 @@ class object : public handle {
     ~object() { dec_ref(); }
 
     /** \rst
-        Resets the internal pointer to ``nullptr`` without without decreasing the
+        Resets the internal pointer to ``nullptr`` without decreasing the
         object's reference count. The function returns a raw handle to the original
         Python object.
     \endrst */
@@ -234,8 +276,8 @@ class object : public handle {
 
 protected:
     // Tags for choosing constructors from raw PyObject *
-    struct borrowed_t { }; static constexpr borrowed_t borrowed{};
-    struct stolen_t { }; static constexpr stolen_t stolen{};
+    struct borrowed_t { };
+    struct stolen_t { };
 
     template <typename T> friend T reinterpret_borrow(handle);
     template <typename T> friend T reinterpret_steal(handle);
@@ -259,7 +301,7 @@ class object : public handle {
         // or
         py::tuple t = reinterpret_borrow<py::tuple>(p); // <-- `p` must be already be a `tuple`
 \endrst */
-template <typename T> T reinterpret_borrow(handle h) { return {h, object::borrowed}; }
+template <typename T> T reinterpret_borrow(handle h) { return {h, object::borrowed_t{}}; }
 
 /** \rst
     Like `reinterpret_borrow`, but steals the reference.
@@ -269,7 +311,64 @@ template <typename T> T reinterpret_borrow(handle h) { return {h, object::borrow
         PyObject *p = PyObject_Str(obj);
         py::str s = reinterpret_steal<py::str>(p); // <-- `p` must be already be a `str`
 \endrst */
-template <typename T> T reinterpret_steal(handle h) { return {h, object::stolen}; }
+template <typename T> T reinterpret_steal(handle h) { return {h, object::stolen_t{}}; }
+
+PYBIND11_NAMESPACE_BEGIN(detail)
+inline std::string error_string();
+PYBIND11_NAMESPACE_END(detail)
+
+/// Fetch and hold an error which was already set in Python.  An instance of this is typically
+/// thrown to propagate python-side errors back through C++ which can either be caught manually or
+/// else falls back to the function dispatcher (which then raises the captured error back to
+/// python).
+class error_already_set : public std::runtime_error {
+public:
+    /// Constructs a new exception from the current Python error indicator, if any.  The current
+    /// Python error indicator will be cleared.
+    error_already_set() : std::runtime_error(detail::error_string()) {
+        PyErr_Fetch(&m_type.ptr(), &m_value.ptr(), &m_trace.ptr());
+    }
+
+    error_already_set(const error_already_set &) = default;
+    error_already_set(error_already_set &&) = default;
+
+    inline ~error_already_set() override;
+
+    /// Give the currently-held error back to Python, if any.  If there is currently a Python error
+    /// already set it is cleared first.  After this call, the current object no longer stores the
+    /// error variables (but the `.what()` string is still available).
+    void restore() { PyErr_Restore(m_type.release().ptr(), m_value.release().ptr(), m_trace.release().ptr()); }
+
+    /// If it is impossible to raise the currently-held error, such as in destructor, we can write
+    /// it out using Python's unraisable hook (sys.unraisablehook). The error context should be
+    /// some object whose repr() helps identify the location of the error. Python already knows the
+    /// type and value of the error, so there is no need to repeat that. For example, __func__ could
+    /// be helpful. After this call, the current object no longer stores the error variables,
+    /// and neither does Python.
+    void discard_as_unraisable(object err_context) {
+        restore();
+        PyErr_WriteUnraisable(err_context.ptr());
+    }
+    void discard_as_unraisable(const char *err_context) {
+        discard_as_unraisable(reinterpret_steal<object>(PYBIND11_FROM_STRING(err_context)));
+    }
+
+    // Does nothing; provided for backwards compatibility.
+    PYBIND11_DEPRECATED("Use of error_already_set.clear() is deprecated")
+    void clear() {}
+
+    /// Check if the currently trapped error type matches the given Python exception class (or a
+    /// subclass thereof).  May also be passed a tuple to search for any exception class matches in
+    /// the given tuple.
+    bool matches(handle exc) const { return PyErr_GivenExceptionMatches(m_type.ptr(), exc.ptr()); }
+
+    const object& type() const { return m_type; }
+    const object& value() const { return m_value; }
+    const object& trace() const { return m_trace; }
+
+private:
+    object m_type, m_value, m_trace;
+};
 
 /** \defgroup python_builtins _
     Unless stated otherwise, the following C++ functions behave the same
@@ -287,7 +386,7 @@ bool isinstance(handle obj) { return T::check_(obj); }
 template <typename T, detail::enable_if_t<!std::is_base_of<object, T>::value, int> = 0>
 bool isinstance(handle obj) { return detail::isinstance_generic(obj, typeid(T)); }
 
-template <> inline bool isinstance<handle>(handle obj) = delete;
+template <> inline bool isinstance<handle>(handle) = delete;
 template <> inline bool isinstance<object>(handle obj) { return obj.ptr() != nullptr; }
 
 /// \ingroup python_builtins
@@ -309,6 +408,14 @@ inline bool hasattr(handle obj, const char *name) {
     return PyObject_HasAttrString(obj.ptr(), name) == 1;
 }
 
+inline void delattr(handle obj, handle name) {
+    if (PyObject_DelAttr(obj.ptr(), name.ptr()) != 0) { throw error_already_set(); }
+}
+
+inline void delattr(handle obj, const char *name) {
+    if (PyObject_DelAttrString(obj.ptr(), name) != 0) { throw error_already_set(); }
+}
+
 inline object getattr(handle obj, handle name) {
     PyObject *result = PyObject_GetAttr(obj.ptr(), name.ptr());
     if (!result) { throw error_already_set(); }
@@ -346,14 +453,22 @@ inline void setattr(handle obj, handle name, handle value) {
 inline void setattr(handle obj, const char *name, handle value) {
     if (PyObject_SetAttrString(obj.ptr(), name, value.ptr()) != 0) { throw error_already_set(); }
 }
+
+inline ssize_t hash(handle obj) {
+    auto h = PyObject_Hash(obj.ptr());
+    if (h == -1) { throw error_already_set(); }
+    return h;
+}
+
 /// @} python_builtins
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 inline handle get_function(handle value) {
     if (value) {
 #if PY_MAJOR_VERSION >= 3
         if (PyInstanceMethod_Check(value.ptr()))
             value = PyInstanceMethod_GET_FUNCTION(value.ptr());
+        else
 #endif
         if (PyMethod_Check(value.ptr()))
             value = PyMethod_GET_FUNCTION(value.ptr());
@@ -372,13 +487,14 @@ object object_or_cast(T &&o);
 // Match a PyObject*, which we want to convert directly to handle via its converting constructor
 inline handle object_or_cast(PyObject *ptr) { return ptr; }
 
-
 template <typename Policy>
 class accessor : public object_api<accessor<Policy>> {
     using key_type = typename Policy::key_type;
 
 public:
     accessor(handle obj, key_type key) : obj(obj), key(std::move(key)) { }
+    accessor(const accessor &) = default;
+    accessor(accessor &&) = default;
 
     // accessor overload required to override default assignment operator (templates are not allowed
     // to replace default compiler-generated assignments).
@@ -420,7 +536,7 @@ class accessor : public object_api<accessor<Policy>> {
     mutable object cache;
 };
 
-NAMESPACE_BEGIN(accessor_policies)
+PYBIND11_NAMESPACE_BEGIN(accessor_policies)
 struct obj_attr {
     using key_type = object;
     static object get(handle obj, handle key) { return getattr(obj, key); }
@@ -497,7 +613,7 @@ struct tuple_item {
         }
     }
 };
-NAMESPACE_END(accessor_policies)
+PYBIND11_NAMESPACE_END(accessor_policies)
 
 /// STL iterator template used for tuple, list, sequence and dict
 template <typename Policy>
@@ -538,7 +654,7 @@ class generic_iterator : public Policy {
     friend bool operator<=(const It &a, const It &b) { return !(a > b); }
 };
 
-NAMESPACE_BEGIN(iterator_policies)
+PYBIND11_NAMESPACE_BEGIN(iterator_policies)
 /// Quick proxy class needed to implement ``operator->`` for iterators which can't return pointers
 template <typename T>
 struct arrow_proxy {
@@ -608,10 +724,10 @@ class dict_readonly {
 
 private:
     handle obj;
-    PyObject *key, *value;
+    PyObject *key = nullptr, *value = nullptr;
     ssize_t pos = -1;
 };
-NAMESPACE_END(iterator_policies)
+PYBIND11_NAMESPACE_END(iterator_policies)
 
 #if !defined(PYPY_VERSION)
 using tuple_iterator = generic_iterator<iterator_policies::sequence_fast_readonly>;
@@ -636,9 +752,12 @@ inline bool PyIterable_Check(PyObject *obj) {
 }
 
 inline bool PyNone_Check(PyObject *o) { return o == Py_None; }
+inline bool PyEllipsis_Check(PyObject *o) { return o == Py_Ellipsis; }
 
 inline bool PyUnicode_Check_Permissive(PyObject *o) { return PyUnicode_Check(o) || PYBIND11_BYTES_CHECK(o); }
 
+inline bool PyStaticMethod_Check(PyObject *o) { return o->ob_type == &PyStaticMethod_Type; }
+
 class kwargs_proxy : public handle {
 public:
     explicit kwargs_proxy(handle h) : handle(h) { }
@@ -665,7 +784,7 @@ class simple_collector;
 template <return_value_policy policy = return_value_policy::automatic_reference>
 class unpacking_collector;
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 // TODO: After the deprecated constructors are removed, this macro can be simplified by
 //       inheriting ctors: `using Parent::Parent`. It's not an option right now because
@@ -674,23 +793,37 @@ NAMESPACE_END(detail)
 #define PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     public: \
         PYBIND11_DEPRECATED("Use reinterpret_borrow<"#Name">() or reinterpret_steal<"#Name">()") \
-        Name(handle h, bool is_borrowed) : Parent(is_borrowed ? Parent(h, borrowed) : Parent(h, stolen)) { } \
-        Name(handle h, borrowed_t) : Parent(h, borrowed) { } \
-        Name(handle h, stolen_t) : Parent(h, stolen) { } \
+        Name(handle h, bool is_borrowed) : Parent(is_borrowed ? Parent(h, borrowed_t{}) : Parent(h, stolen_t{})) { } \
+        Name(handle h, borrowed_t) : Parent(h, borrowed_t{}) { } \
+        Name(handle h, stolen_t) : Parent(h, stolen_t{}) { } \
         PYBIND11_DEPRECATED("Use py::isinstance<py::python_type>(obj) instead") \
         bool check() const { return m_ptr != nullptr && (bool) CheckFun(m_ptr); } \
-        static bool check_(handle h) { return h.ptr() != nullptr && CheckFun(h.ptr()); }
+        static bool check_(handle h) { return h.ptr() != nullptr && CheckFun(h.ptr()); } \
+        template <typename Policy_> \
+        Name(const ::pybind11::detail::accessor<Policy_> &a) : Name(object(a)) { }
 
 #define PYBIND11_OBJECT_CVT(Name, Parent, CheckFun, ConvertFun) \
     PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     /* This is deliberately not 'explicit' to allow implicit conversion from object: */ \
-    Name(const object &o) : Parent(ConvertFun(o.ptr()), stolen) { if (!m_ptr) throw error_already_set(); }
+    Name(const object &o) \
+    : Parent(check_(o) ? o.inc_ref().ptr() : ConvertFun(o.ptr()), stolen_t{}) \
+    { if (!m_ptr) throw error_already_set(); } \
+    Name(object &&o) \
+    : Parent(check_(o) ? o.release().ptr() : ConvertFun(o.ptr()), stolen_t{}) \
+    { if (!m_ptr) throw error_already_set(); }
+
+#define PYBIND11_OBJECT_CHECK_FAILED(Name, o) \
+    ::pybind11::type_error("Object of type '" + \
+                           ::pybind11::detail::get_fully_qualified_tp_name(Py_TYPE(o.ptr())) + \
+                           "' is not an instance of '" #Name "'")
 
 #define PYBIND11_OBJECT(Name, Parent, CheckFun) \
     PYBIND11_OBJECT_COMMON(Name, Parent, CheckFun) \
     /* This is deliberately not 'explicit' to allow implicit conversion from object: */ \
-    Name(const object &o) : Parent(o) { } \
-    Name(object &&o) : Parent(std::move(o)) { }
+    Name(const object &o) : Parent(o) \
+    { if (o && !check_(o)) throw PYBIND11_OBJECT_CHECK_FAILED(Name, o); } \
+    Name(object &&o) : Parent(std::move(o)) \
+    { if (o && !check_(o)) throw PYBIND11_OBJECT_CHECK_FAILED(Name, o); }
 
 #define PYBIND11_OBJECT_DEFAULT(Name, Parent, CheckFun) \
     PYBIND11_OBJECT(Name, Parent, CheckFun) \
@@ -766,6 +899,32 @@ class iterator : public object {
     object value = {};
 };
 
+
+
+class type : public object {
+public:
+    PYBIND11_OBJECT(type, object, PyType_Check)
+
+    /// Return a type handle from a handle or an object
+    static handle handle_of(handle h) { return handle((PyObject*) Py_TYPE(h.ptr())); }
+
+    /// Return a type object from a handle or an object
+    static type of(handle h) { return type(type::handle_of(h), borrowed_t{}); }
+
+    // Defined in pybind11/cast.h
+    /// Convert C++ type to handle if previously registered. Does not convert
+    /// standard types, like int, float. etc. yet.
+    /// See https://github.com/pybind/pybind11/issues/2486
+    template<typename T>
+    static handle handle_of();
+
+    /// Convert C++ type to type if previously registered. Does not convert
+    /// standard types, like int, float. etc. yet.
+    /// See https://github.com/pybind/pybind11/issues/2486
+    template<typename T>
+    static type of() {return type(type::handle_of<T>(), borrowed_t{}); }
+};
+
 class iterable : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(iterable, object, detail::PyIterable_Check)
@@ -778,13 +937,13 @@ class str : public object {
     PYBIND11_OBJECT_CVT(str, object, detail::PyUnicode_Check_Permissive, raw_str)
 
     str(const char *c, size_t n)
-        : object(PyUnicode_FromStringAndSize(c, (ssize_t) n), stolen) {
+        : object(PyUnicode_FromStringAndSize(c, (ssize_t) n), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate string object!");
     }
 
     // 'explicit' is explicitly omitted from the following constructors to allow implicit conversion to py::str from C++ string-like objects
     str(const char *c = "")
-        : object(PyUnicode_FromString(c), stolen) {
+        : object(PyUnicode_FromString(c), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate string object!");
     }
 
@@ -796,7 +955,7 @@ class str : public object {
         Return a string representation of the object. This is analogous to
         the ``str()`` function in Python.
     \endrst */
-    explicit str(handle h) : object(raw_str(h.ptr()), stolen) { }
+    explicit str(handle h) : object(raw_str(h.ptr()), stolen_t{}) { if (!m_ptr) throw error_already_set(); }
 
     operator std::string() const {
         object temp = *this;
@@ -836,7 +995,7 @@ inline namespace literals {
     String literal version of `str`
  \endrst */
 inline str operator"" _s(const char *s, size_t size) { return {s, size}; }
-}
+} // namespace literals
 
 /// \addtogroup pytypes
 /// @{
@@ -846,12 +1005,12 @@ class bytes : public object {
 
     // Allow implicit conversion:
     bytes(const char *c = "")
-        : object(PYBIND11_BYTES_FROM_STRING(c), stolen) {
+        : object(PYBIND11_BYTES_FROM_STRING(c), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
     }
 
     bytes(const char *c, size_t n)
-        : object(PYBIND11_BYTES_FROM_STRING_AND_SIZE(c, (ssize_t) n), stolen) {
+        : object(PYBIND11_BYTES_FROM_STRING_AND_SIZE(c, (ssize_t) n), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
     }
 
@@ -868,6 +1027,9 @@ class bytes : public object {
         return std::string(buffer, (size_t) length);
     }
 };
+// Note: breathe >= 4.17.0 will fail to build docs if the below two constructors
+// are included in the doxygen group; close here and reopen after as a workaround
+/// @} pytypes
 
 inline bytes::bytes(const pybind11::str &s) {
     object temp = s;
@@ -897,18 +1059,26 @@ inline str::str(const bytes& b) {
     m_ptr = obj.release().ptr();
 }
 
+/// \addtogroup pytypes
+/// @{
 class none : public object {
 public:
     PYBIND11_OBJECT(none, object, detail::PyNone_Check)
-    none() : object(Py_None, borrowed) { }
+    none() : object(Py_None, borrowed_t{}) { }
+};
+
+class ellipsis : public object {
+public:
+    PYBIND11_OBJECT(ellipsis, object, detail::PyEllipsis_Check)
+    ellipsis() : object(Py_Ellipsis, borrowed_t{}) { }
 };
 
 class bool_ : public object {
 public:
     PYBIND11_OBJECT_CVT(bool_, object, PyBool_Check, raw_bool)
-    bool_() : object(Py_False, borrowed) { }
+    bool_() : object(Py_False, borrowed_t{}) { }
     // Allow implicit conversion from and to `bool`:
-    bool_(bool value) : object(value ? Py_True : Py_False, borrowed) { }
+    bool_(bool value) : object(value ? Py_True : Py_False, borrowed_t{}) { }
     operator bool() const { return m_ptr && PyLong_AsLong(m_ptr) != 0; }
 
 private:
@@ -920,10 +1090,32 @@ class bool_ : public object {
     }
 };
 
+PYBIND11_NAMESPACE_BEGIN(detail)
+// Converts a value to the given unsigned type.  If an error occurs, you get back (Unsigned) -1;
+// otherwise you get back the unsigned long or unsigned long long value cast to (Unsigned).
+// (The distinction is critically important when casting a returned -1 error value to some other
+// unsigned type: (A)-1 != (B)-1 when A and B are unsigned types of different sizes).
+template <typename Unsigned>
+Unsigned as_unsigned(PyObject *o) {
+    if (sizeof(Unsigned) <= sizeof(unsigned long)
+#if PY_VERSION_HEX < 0x03000000
+            || PyInt_Check(o)
+#endif
+    ) {
+        unsigned long v = PyLong_AsUnsignedLong(o);
+        return v == (unsigned long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
+    }
+    else {
+        unsigned long long v = PyLong_AsUnsignedLongLong(o);
+        return v == (unsigned long long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
+    }
+}
+PYBIND11_NAMESPACE_END(detail)
+
 class int_ : public object {
 public:
     PYBIND11_OBJECT_CVT(int_, object, PYBIND11_LONG_CHECK, PyNumber_Long)
-    int_() : object(PyLong_FromLong(0), stolen) { }
+    int_() : object(PyLong_FromLong(0), stolen_t{}) { }
     // Allow implicit conversion from C++ integral types:
     template <typename T,
               detail::enable_if_t<std::is_integral<T>::value, int> = 0>
@@ -945,17 +1137,11 @@ class int_ : public object {
     template <typename T,
               detail::enable_if_t<std::is_integral<T>::value, int> = 0>
     operator T() const {
-        if (sizeof(T) <= sizeof(long)) {
-            if (std::is_signed<T>::value)
-                return (T) PyLong_AsLong(m_ptr);
-            else
-                return (T) PyLong_AsUnsignedLong(m_ptr);
-        } else {
-            if (std::is_signed<T>::value)
-                return (T) PYBIND11_LONG_AS_LONGLONG(m_ptr);
-            else
-                return (T) PYBIND11_LONG_AS_UNSIGNED_LONGLONG(m_ptr);
-        }
+        return std::is_unsigned<T>::value
+            ? detail::as_unsigned<T>(m_ptr)
+            : sizeof(T) <= sizeof(long)
+              ? (T) PyLong_AsLong(m_ptr)
+              : (T) PYBIND11_LONG_AS_LONGLONG(m_ptr);
     }
 };
 
@@ -963,10 +1149,10 @@ class float_ : public object {
 public:
     PYBIND11_OBJECT_CVT(float_, object, PyFloat_Check, PyNumber_Float)
     // Allow implicit conversion from float/double:
-    float_(float value) : object(PyFloat_FromDouble((double) value), stolen) {
+    float_(float value) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate float object!");
     }
-    float_(double value = .0) : object(PyFloat_FromDouble((double) value), stolen) {
+    float_(double value = .0) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate float object!");
     }
     operator float() const { return (float) PyFloat_AsDouble(m_ptr); }
@@ -977,7 +1163,7 @@ class weakref : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(weakref, object, PyWeakref_Check)
     explicit weakref(handle obj, handle callback = {})
-        : object(PyWeakref_NewRef(obj.ptr(), callback.ptr()), stolen) {
+        : object(PyWeakref_NewRef(obj.ptr(), callback.ptr()), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate weak reference!");
     }
 };
@@ -997,23 +1183,30 @@ class slice : public object {
                                     (ssize_t *) stop, (ssize_t *) step,
                                     (ssize_t *) slicelength) == 0;
     }
+    bool compute(ssize_t length, ssize_t *start, ssize_t *stop, ssize_t *step,
+      ssize_t *slicelength) const {
+      return PySlice_GetIndicesEx((PYBIND11_SLICE_OBJECT *) m_ptr,
+          length, start,
+          stop, step,
+          slicelength) == 0;
+    }
 };
 
 class capsule : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(capsule, object, PyCapsule_CheckExact)
     PYBIND11_DEPRECATED("Use reinterpret_borrow<capsule>() or reinterpret_steal<capsule>()")
-    capsule(PyObject *ptr, bool is_borrowed) : object(is_borrowed ? object(ptr, borrowed) : object(ptr, stolen)) { }
+    capsule(PyObject *ptr, bool is_borrowed) : object(is_borrowed ? object(ptr, borrowed_t{}) : object(ptr, stolen_t{})) { }
 
-    explicit capsule(const void *value)
-        : object(PyCapsule_New(const_cast<void *>(value), nullptr, nullptr), stolen) {
+    explicit capsule(const void *value, const char *name = nullptr, void (*destructor)(PyObject *) = nullptr)
+        : object(PyCapsule_New(const_cast<void *>(value), name, destructor), stolen_t{}) {
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
     }
 
     PYBIND11_DEPRECATED("Please pass a destructor that takes a void pointer as input")
     capsule(const void *value, void (*destruct)(PyObject *))
-        : object(PyCapsule_New(const_cast<void*>(value), nullptr, destruct), stolen) {
+        : object(PyCapsule_New(const_cast<void*>(value), nullptr, destruct), stolen_t{}) {
         if (!m_ptr)
             pybind11_fail("Could not allocate capsule object!");
     }
@@ -1043,20 +1236,37 @@ class capsule : public object {
     }
 
     template <typename T> operator T *() const {
-        T * result = static_cast<T *>(PyCapsule_GetPointer(m_ptr, nullptr));
+        return get_pointer<T>();
+    }
+
+    /// Get the pointer the capsule holds.
+    template<typename T = void>
+    T* get_pointer() const {
+        auto name = this->name();
+        T *result = static_cast<T *>(PyCapsule_GetPointer(m_ptr, name));
         if (!result) pybind11_fail("Unable to extract capsule contents!");
         return result;
     }
+
+    /// Replaces a capsule's pointer *without* calling the destructor on the existing one.
+    void set_pointer(const void *value) {
+        if (PyCapsule_SetPointer(m_ptr, const_cast<void *>(value)) != 0)
+            pybind11_fail("Could not set capsule pointer");
+    }
+
+    const char *name() const { return PyCapsule_GetName(m_ptr); }
 };
 
 class tuple : public object {
 public:
     PYBIND11_OBJECT_CVT(tuple, object, PyTuple_Check, PySequence_Tuple)
-    explicit tuple(size_t size = 0) : object(PyTuple_New((ssize_t) size), stolen) {
+    explicit tuple(size_t size = 0) : object(PyTuple_New((ssize_t) size), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate tuple object!");
     }
     size_t size() const { return (size_t) PyTuple_Size(m_ptr); }
+    bool empty() const { return size() == 0; }
     detail::tuple_accessor operator[](size_t index) const { return {*this, index}; }
+    detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::tuple_iterator begin() const { return {*this, 0}; }
     detail::tuple_iterator end() const { return {*this, PyTuple_GET_SIZE(m_ptr)}; }
 };
@@ -1064,7 +1274,7 @@ class tuple : public object {
 class dict : public object {
 public:
     PYBIND11_OBJECT_CVT(dict, object, PyDict_Check, raw_dict)
-    dict() : object(PyDict_New(), stolen) {
+    dict() : object(PyDict_New(), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate dict object!");
     }
     template <typename... Args,
@@ -1074,11 +1284,13 @@ class dict : public object {
     explicit dict(Args &&...args) : dict(collector(std::forward<Args>(args)...).kwargs()) { }
 
     size_t size() const { return (size_t) PyDict_Size(m_ptr); }
+    bool empty() const { return size() == 0; }
     detail::dict_iterator begin() const { return {*this, 0}; }
     detail::dict_iterator end() const { return {}; }
     void clear() const { PyDict_Clear(ptr()); }
-    bool contains(handle key) const { return PyDict_Contains(ptr(), key.ptr()) == 1; }
-    bool contains(const char *key) const { return PyDict_Contains(ptr(), pybind11::str(key).ptr()) == 1; }
+    template <typename T> bool contains(T &&key) const {
+        return PyDict_Contains(m_ptr, detail::object_or_cast(std::forward<T>(key)).ptr()) == 1;
+    }
 
 private:
     /// Call the `dict` Python type -- always returns a new reference
@@ -1092,8 +1304,15 @@ class dict : public object {
 class sequence : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(sequence, object, PySequence_Check)
-    size_t size() const { return (size_t) PySequence_Size(m_ptr); }
+    size_t size() const {
+        ssize_t result = PySequence_Size(m_ptr);
+        if (result == -1)
+            throw error_already_set();
+        return (size_t) result;
+    }
+    bool empty() const { return size() == 0; }
     detail::sequence_accessor operator[](size_t index) const { return {*this, index}; }
+    detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::sequence_iterator begin() const { return {*this, 0}; }
     detail::sequence_iterator end() const { return {*this, PySequence_Size(m_ptr)}; }
 };
@@ -1101,16 +1320,22 @@ class sequence : public object {
 class list : public object {
 public:
     PYBIND11_OBJECT_CVT(list, object, PyList_Check, PySequence_List)
-    explicit list(size_t size = 0) : object(PyList_New((ssize_t) size), stolen) {
+    explicit list(size_t size = 0) : object(PyList_New((ssize_t) size), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate list object!");
     }
     size_t size() const { return (size_t) PyList_Size(m_ptr); }
+    bool empty() const { return size() == 0; }
     detail::list_accessor operator[](size_t index) const { return {*this, index}; }
+    detail::item_accessor operator[](handle h) const { return object::operator[](h); }
     detail::list_iterator begin() const { return {*this, 0}; }
     detail::list_iterator end() const { return {*this, PyList_GET_SIZE(m_ptr)}; }
     template <typename T> void append(T &&val) const {
         PyList_Append(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr());
     }
+    template <typename T> void insert(size_t index, T &&val) const {
+        PyList_Insert(m_ptr, static_cast<ssize_t>(index),
+            detail::object_or_cast(std::forward<T>(val)).ptr());
+    }
 };
 
 class args : public tuple { PYBIND11_OBJECT_DEFAULT(args, tuple, PyTuple_Check) };
@@ -1119,78 +1344,215 @@ class kwargs : public dict { PYBIND11_OBJECT_DEFAULT(kwargs, dict, PyDict_Check)
 class set : public object {
 public:
     PYBIND11_OBJECT_CVT(set, object, PySet_Check, PySet_New)
-    set() : object(PySet_New(nullptr), stolen) {
+    set() : object(PySet_New(nullptr), stolen_t{}) {
         if (!m_ptr) pybind11_fail("Could not allocate set object!");
     }
     size_t size() const { return (size_t) PySet_Size(m_ptr); }
+    bool empty() const { return size() == 0; }
     template <typename T> bool add(T &&val) const {
         return PySet_Add(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr()) == 0;
     }
     void clear() const { PySet_Clear(m_ptr); }
+    template <typename T> bool contains(T &&val) const {
+        return PySet_Contains(m_ptr, detail::object_or_cast(std::forward<T>(val)).ptr()) == 1;
+    }
 };
 
 class function : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(function, object, PyCallable_Check)
-    bool is_cpp_function() const {
+    handle cpp_function() const {
         handle fun = detail::get_function(m_ptr);
-        return fun && PyCFunction_Check(fun.ptr());
+        if (fun && PyCFunction_Check(fun.ptr()))
+            return fun;
+        return handle();
     }
+    bool is_cpp_function() const { return (bool) cpp_function(); }
+};
+
+class staticmethod : public object {
+public:
+    PYBIND11_OBJECT_CVT(staticmethod, object, detail::PyStaticMethod_Check, PyStaticMethod_New)
 };
 
 class buffer : public object {
 public:
     PYBIND11_OBJECT_DEFAULT(buffer, object, PyObject_CheckBuffer)
 
-    buffer_info request(bool writable = false) {
+    buffer_info request(bool writable = false) const {
         int flags = PyBUF_STRIDES | PyBUF_FORMAT;
         if (writable) flags |= PyBUF_WRITABLE;
-        Py_buffer *view = new Py_buffer();
-        if (PyObject_GetBuffer(m_ptr, view, flags) != 0)
+        auto *view = new Py_buffer();
+        if (PyObject_GetBuffer(m_ptr, view, flags) != 0) {
+            delete view;
             throw error_already_set();
+        }
         return buffer_info(view);
     }
 };
 
 class memoryview : public object {
 public:
-    explicit memoryview(const buffer_info& info) {
-        static Py_buffer buf { };
-        // Py_buffer uses signed sizes, strides and shape!..
-        static std::vector<Py_ssize_t> py_strides { };
-        static std::vector<Py_ssize_t> py_shape { };
-        buf.buf = info.ptr;
-        buf.itemsize = (Py_ssize_t) info.itemsize;
-        buf.format = const_cast<char *>(info.format.c_str());
-        buf.ndim = (int) info.ndim;
-        buf.len = (Py_ssize_t) info.size;
-        py_strides.clear();
-        py_shape.clear();
-        for (size_t i = 0; i < info.ndim; ++i) {
-            py_strides.push_back((Py_ssize_t) info.strides[i]);
-            py_shape.push_back((Py_ssize_t) info.shape[i]);
-        }
-        buf.strides = py_strides.data();
-        buf.shape = py_shape.data();
-        buf.suboffsets = nullptr;
-        buf.readonly = false;
-        buf.internal = nullptr;
+    PYBIND11_OBJECT_CVT(memoryview, object, PyMemoryView_Check, PyMemoryView_FromObject)
+
+    /** \rst
+        Creates ``memoryview`` from ``buffer_info``.
+
+        ``buffer_info`` must be created from ``buffer::request()``. Otherwise
+        throws an exception.
 
-        m_ptr = PyMemoryView_FromBuffer(&buf);
+        For creating a ``memoryview`` from objects that support buffer protocol,
+        use ``memoryview(const object& obj)`` instead of this constructor.
+     \endrst */
+    explicit memoryview(const buffer_info& info) {
+        if (!info.view())
+            pybind11_fail("Prohibited to create memoryview without Py_buffer");
+        // Note: PyMemoryView_FromBuffer never increments obj reference.
+        m_ptr = (info.view()->obj) ?
+            PyMemoryView_FromObject(info.view()->obj) :
+            PyMemoryView_FromBuffer(info.view());
         if (!m_ptr)
             pybind11_fail("Unable to create memoryview from buffer descriptor");
     }
 
-    PYBIND11_OBJECT_CVT(memoryview, object, PyMemoryView_Check, PyMemoryView_FromObject)
+    /** \rst
+        Creates ``memoryview`` from static buffer.
+
+        This method is meant for providing a ``memoryview`` for C/C++ buffer not
+        managed by Python. The caller is responsible for managing the lifetime
+        of ``ptr`` and ``format``, which MUST outlive the memoryview constructed
+        here.
+
+        See also: Python C API documentation for `PyMemoryView_FromBuffer`_.
+
+        .. _PyMemoryView_FromBuffer: https://docs.python.org/c-api/memoryview.html#c.PyMemoryView_FromBuffer
+
+        :param ptr: Pointer to the buffer.
+        :param itemsize: Byte size of an element.
+        :param format: Pointer to the null-terminated format string. For
+            homogeneous Buffers, this should be set to
+            ``format_descriptor<T>::value``.
+        :param shape: Shape of the tensor (1 entry per dimension).
+        :param strides: Number of bytes between adjacent entries (for each
+            per dimension).
+        :param readonly: Flag to indicate if the underlying storage may be
+            written to.
+     \endrst */
+    static memoryview from_buffer(
+        void *ptr, ssize_t itemsize, const char *format,
+        detail::any_container<ssize_t> shape,
+        detail::any_container<ssize_t> strides, bool readonly = false);
+
+    static memoryview from_buffer(
+        const void *ptr, ssize_t itemsize, const char *format,
+        detail::any_container<ssize_t> shape,
+        detail::any_container<ssize_t> strides) {
+        return memoryview::from_buffer(
+            const_cast<void*>(ptr), itemsize, format, shape, strides, true);
+    }
+
+    template<typename T>
+    static memoryview from_buffer(
+        T *ptr, detail::any_container<ssize_t> shape,
+        detail::any_container<ssize_t> strides, bool readonly = false) {
+        return memoryview::from_buffer(
+            reinterpret_cast<void*>(ptr), sizeof(T),
+            format_descriptor<T>::value, shape, strides, readonly);
+    }
+
+    template<typename T>
+    static memoryview from_buffer(
+        const T *ptr, detail::any_container<ssize_t> shape,
+        detail::any_container<ssize_t> strides) {
+        return memoryview::from_buffer(
+            const_cast<T*>(ptr), shape, strides, true);
+    }
+
+#if PY_MAJOR_VERSION >= 3
+    /** \rst
+        Creates ``memoryview`` from static memory.
+
+        This method is meant for providing a ``memoryview`` for C/C++ buffer not
+        managed by Python. The caller is responsible for managing the lifetime
+        of ``mem``, which MUST outlive the memoryview constructed here.
+
+        This method is not available in Python 2.
+
+        See also: Python C API documentation for `PyMemoryView_FromBuffer`_.
+
+        .. _PyMemoryView_FromMemory: https://docs.python.org/c-api/memoryview.html#c.PyMemoryView_FromMemory
+     \endrst */
+    static memoryview from_memory(void *mem, ssize_t size, bool readonly = false) {
+        PyObject* ptr = PyMemoryView_FromMemory(
+            reinterpret_cast<char*>(mem), size,
+            (readonly) ? PyBUF_READ : PyBUF_WRITE);
+        if (!ptr)
+            pybind11_fail("Could not allocate memoryview object!");
+        return memoryview(object(ptr, stolen_t{}));
+    }
+
+    static memoryview from_memory(const void *mem, ssize_t size) {
+        return memoryview::from_memory(const_cast<void*>(mem), size, true);
+    }
+#endif
 };
+
+#ifndef DOXYGEN_SHOULD_SKIP_THIS
+inline memoryview memoryview::from_buffer(
+    void *ptr, ssize_t itemsize, const char* format,
+    detail::any_container<ssize_t> shape,
+    detail::any_container<ssize_t> strides, bool readonly) {
+    size_t ndim = shape->size();
+    if (ndim != strides->size())
+        pybind11_fail("memoryview: shape length doesn't match strides length");
+    ssize_t size = ndim ? 1 : 0;
+    for (size_t i = 0; i < ndim; ++i)
+        size *= (*shape)[i];
+    Py_buffer view;
+    view.buf = ptr;
+    view.obj = nullptr;
+    view.len = size * itemsize;
+    view.readonly = static_cast<int>(readonly);
+    view.itemsize = itemsize;
+    view.format = const_cast<char*>(format);
+    view.ndim = static_cast<int>(ndim);
+    view.shape = shape->data();
+    view.strides = strides->data();
+    view.suboffsets = nullptr;
+    view.internal = nullptr;
+    PyObject* obj = PyMemoryView_FromBuffer(&view);
+    if (!obj)
+        throw error_already_set();
+    return memoryview(object(obj, stolen_t{}));
+}
+#endif  // DOXYGEN_SHOULD_SKIP_THIS
 /// @} pytypes
 
 /// \addtogroup python_builtins
 /// @{
+
+/// Get the length of a Python object.
 inline size_t len(handle h) {
     ssize_t result = PyObject_Length(h.ptr());
     if (result < 0)
-        pybind11_fail("Unable to compute length of object");
+        throw error_already_set();
+    return (size_t) result;
+}
+
+/// Get the length hint of a Python object.
+/// Returns 0 when this cannot be determined.
+inline size_t len_hint(handle h) {
+#if PY_VERSION_HEX >= 0x03040000
+    ssize_t result = PyObject_LengthHint(h.ptr(), 0);
+#else
+    ssize_t result = PyObject_Length(h.ptr());
+#endif
+    if (result < 0) {
+        // Sometimes a length can't be determined at all (eg generators)
+        // In which case simply return 0
+        PyErr_Clear();
+        return 0;
+    }
     return (size_t) result;
 }
 
@@ -1212,7 +1574,7 @@ inline iterator iter(handle obj) {
 }
 /// @} python_builtins
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 template <typename D> iterator object_api<D>::begin() const { return iter(derived()); }
 template <typename D> iterator object_api<D>::end() const { return iterator::sentinel(); }
 template <typename D> item_accessor object_api<D>::operator[](handle key) const {
@@ -1238,7 +1600,60 @@ template <typename D>
 pybind11::str object_api<D>::str() const { return pybind11::str(derived()); }
 
 template <typename D>
-handle object_api<D>::get_type() const { return (PyObject *) Py_TYPE(derived().ptr()); }
+str_attr_accessor object_api<D>::doc() const { return attr("__doc__"); }
+
+template <typename D>
+handle object_api<D>::get_type() const { return type::handle_of(derived()); }
+
+template <typename D>
+bool object_api<D>::rich_compare(object_api const &other, int value) const {
+    int rv = PyObject_RichCompareBool(derived().ptr(), other.derived().ptr(), value);
+    if (rv == -1)
+        throw error_already_set();
+    return rv == 1;
+}
+
+#define PYBIND11_MATH_OPERATOR_UNARY(op, fn)                                   \
+    template <typename D> object object_api<D>::op() const {                   \
+        object result = reinterpret_steal<object>(fn(derived().ptr()));        \
+        if (!result.ptr())                                                     \
+            throw error_already_set();                                         \
+        return result;                                                         \
+    }
+
+#define PYBIND11_MATH_OPERATOR_BINARY(op, fn)                                  \
+    template <typename D>                                                      \
+    object object_api<D>::op(object_api const &other) const {                  \
+        object result = reinterpret_steal<object>(                             \
+            fn(derived().ptr(), other.derived().ptr()));                       \
+        if (!result.ptr())                                                     \
+            throw error_already_set();                                         \
+        return result;                                                         \
+    }
 
-NAMESPACE_END(detail)
-NAMESPACE_END(pybind11)
+PYBIND11_MATH_OPERATOR_UNARY (operator~,   PyNumber_Invert)
+PYBIND11_MATH_OPERATOR_UNARY (operator-,   PyNumber_Negative)
+PYBIND11_MATH_OPERATOR_BINARY(operator+,   PyNumber_Add)
+PYBIND11_MATH_OPERATOR_BINARY(operator+=,  PyNumber_InPlaceAdd)
+PYBIND11_MATH_OPERATOR_BINARY(operator-,   PyNumber_Subtract)
+PYBIND11_MATH_OPERATOR_BINARY(operator-=,  PyNumber_InPlaceSubtract)
+PYBIND11_MATH_OPERATOR_BINARY(operator*,   PyNumber_Multiply)
+PYBIND11_MATH_OPERATOR_BINARY(operator*=,  PyNumber_InPlaceMultiply)
+PYBIND11_MATH_OPERATOR_BINARY(operator/,   PyNumber_TrueDivide)
+PYBIND11_MATH_OPERATOR_BINARY(operator/=,  PyNumber_InPlaceTrueDivide)
+PYBIND11_MATH_OPERATOR_BINARY(operator|,   PyNumber_Or)
+PYBIND11_MATH_OPERATOR_BINARY(operator|=,  PyNumber_InPlaceOr)
+PYBIND11_MATH_OPERATOR_BINARY(operator&,   PyNumber_And)
+PYBIND11_MATH_OPERATOR_BINARY(operator&=,  PyNumber_InPlaceAnd)
+PYBIND11_MATH_OPERATOR_BINARY(operator^,   PyNumber_Xor)
+PYBIND11_MATH_OPERATOR_BINARY(operator^=,  PyNumber_InPlaceXor)
+PYBIND11_MATH_OPERATOR_BINARY(operator<<,  PyNumber_Lshift)
+PYBIND11_MATH_OPERATOR_BINARY(operator<<=, PyNumber_InPlaceLshift)
+PYBIND11_MATH_OPERATOR_BINARY(operator>>,  PyNumber_Rshift)
+PYBIND11_MATH_OPERATOR_BINARY(operator>>=, PyNumber_InPlaceRshift)
+
+#undef PYBIND11_MATH_OPERATOR_UNARY
+#undef PYBIND11_MATH_OPERATOR_BINARY
+
+PYBIND11_NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/libs/pybind/pybind11/stl.h b/libs/pybind/pybind11/stl.h
index 4b557bd16f..721bb669f0 100644
--- a/libs/pybind/pybind11/stl.h
+++ b/libs/pybind/pybind11/stl.h
@@ -16,6 +16,7 @@
 #include <unordered_map>
 #include <iostream>
 #include <list>
+#include <deque>
 #include <valarray>
 
 #if defined(_MSC_VER)
@@ -30,16 +31,38 @@
 #    define PYBIND11_HAS_OPTIONAL 1
 #  endif
 // std::experimental::optional (but not allowed in c++11 mode)
-#  if defined(PYBIND11_CPP14) && __has_include(<experimental/optional>)
+#  if defined(PYBIND11_CPP14) && (__has_include(<experimental/optional>) && \
+                                 !__has_include(<optional>))
 #    include <experimental/optional>
-#    if __cpp_lib_experimental_optional  // just in case
-#      define PYBIND11_HAS_EXP_OPTIONAL 1
-#    endif
+#    define PYBIND11_HAS_EXP_OPTIONAL 1
 #  endif
+// std::variant
+#  if defined(PYBIND11_CPP17) && __has_include(<variant>)
+#    include <variant>
+#    define PYBIND11_HAS_VARIANT 1
+#  endif
+#elif defined(_MSC_VER) && defined(PYBIND11_CPP17)
+#  include <optional>
+#  include <variant>
+#  define PYBIND11_HAS_OPTIONAL 1
+#  define PYBIND11_HAS_VARIANT 1
 #endif
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
+
+/// Extracts an const lvalue reference or rvalue reference for U based on the type of T (e.g. for
+/// forwarding a container element).  Typically used indirect via forwarded_type(), below.
+template <typename T, typename U>
+using forwarded_type = conditional_t<
+    std::is_lvalue_reference<T>::value, remove_reference_t<U> &, remove_reference_t<U> &&>;
+
+/// Forwards a value U as rvalue or lvalue according to whether T is rvalue or lvalue; typically
+/// used for forwarding a container's elements.
+template <typename T, typename U>
+forwarded_type<T, U> forward_like(U &&u) {
+    return std::forward<detail::forwarded_type<T, U>>(std::forward<U>(u));
+}
 
 template <typename Type, typename Key> struct set_caster {
     using type = Type;
@@ -50,26 +73,29 @@ template <typename Type, typename Key> struct set_caster {
             return false;
         auto s = reinterpret_borrow<pybind11::set>(src);
         value.clear();
-        key_conv conv;
         for (auto entry : s) {
+            key_conv conv;
             if (!conv.load(entry, convert))
                 return false;
-            value.insert(cast_op<Key>(conv));
+            value.insert(cast_op<Key &&>(std::move(conv)));
         }
         return true;
     }
 
-    static handle cast(const type &src, return_value_policy policy, handle parent) {
+    template <typename T>
+    static handle cast(T &&src, return_value_policy policy, handle parent) {
+        if (!std::is_lvalue_reference<T>::value)
+            policy = return_value_policy_override<Key>::policy(policy);
         pybind11::set s;
-        for (auto const &value: src) {
-            auto value_ = reinterpret_steal<object>(key_conv::cast(value, policy, parent));
+        for (auto &&value : src) {
+            auto value_ = reinterpret_steal<object>(key_conv::cast(forward_like<T>(value), policy, parent));
             if (!value_ || !s.add(value_))
                 return handle();
         }
         return s.release();
     }
 
-    PYBIND11_TYPE_CASTER(type, _("Set[") + key_conv::name() + _("]"));
+    PYBIND11_TYPE_CASTER(type, _("Set[") + key_conv::name + _("]"));
 };
 
 template <typename Type, typename Key, typename Value> struct map_caster {
@@ -80,23 +106,30 @@ template <typename Type, typename Key, typename Value> struct map_caster {
         if (!isinstance<dict>(src))
             return false;
         auto d = reinterpret_borrow<dict>(src);
-        key_conv kconv;
-        value_conv vconv;
         value.clear();
         for (auto it : d) {
+            key_conv kconv;
+            value_conv vconv;
             if (!kconv.load(it.first.ptr(), convert) ||
                 !vconv.load(it.second.ptr(), convert))
                 return false;
-            value.emplace(cast_op<Key>(kconv), cast_op<Value>(vconv));
+            value.emplace(cast_op<Key &&>(std::move(kconv)), cast_op<Value &&>(std::move(vconv)));
         }
         return true;
     }
 
-    static handle cast(const Type &src, return_value_policy policy, handle parent) {
+    template <typename T>
+    static handle cast(T &&src, return_value_policy policy, handle parent) {
         dict d;
-        for (auto const &kv: src) {
-            auto key = reinterpret_steal<object>(key_conv::cast(kv.first, policy, parent));
-            auto value = reinterpret_steal<object>(value_conv::cast(kv.second, policy, parent));
+        return_value_policy policy_key = policy;
+        return_value_policy policy_value = policy;
+        if (!std::is_lvalue_reference<T>::value) {
+            policy_key = return_value_policy_override<Key>::policy(policy_key);
+            policy_value = return_value_policy_override<Value>::policy(policy_value);
+        }
+        for (auto &&kv : src) {
+            auto key = reinterpret_steal<object>(key_conv::cast(forward_like<T>(kv.first), policy_key, parent));
+            auto value = reinterpret_steal<object>(value_conv::cast(forward_like<T>(kv.second), policy_value, parent));
             if (!key || !value)
                 return handle();
             d[key] = value;
@@ -104,23 +137,23 @@ template <typename Type, typename Key, typename Value> struct map_caster {
         return d.release();
     }
 
-    PYBIND11_TYPE_CASTER(Type, _("Dict[") + key_conv::name() + _(", ") + value_conv::name() + _("]"));
+    PYBIND11_TYPE_CASTER(Type, _("Dict[") + key_conv::name + _(", ") + value_conv::name + _("]"));
 };
 
 template <typename Type, typename Value> struct list_caster {
     using value_conv = make_caster<Value>;
 
     bool load(handle src, bool convert) {
-        if (!isinstance<sequence>(src))
+        if (!isinstance<sequence>(src) || isinstance<str>(src))
             return false;
         auto s = reinterpret_borrow<sequence>(src);
-        value_conv conv;
         value.clear();
         reserve_maybe(s, &value);
         for (auto it : s) {
+            value_conv conv;
             if (!conv.load(it, convert))
                 return false;
-            value.push_back(cast_op<Value>(conv));
+            value.push_back(cast_op<Value &&>(std::move(conv)));
         }
         return true;
     }
@@ -132,11 +165,14 @@ template <typename Type, typename Value> struct list_caster {
     void reserve_maybe(sequence, void *) { }
 
 public:
-    static handle cast(const Type &src, return_value_policy policy, handle parent) {
+    template <typename T>
+    static handle cast(T &&src, return_value_policy policy, handle parent) {
+        if (!std::is_lvalue_reference<T>::value)
+            policy = return_value_policy_override<Value>::policy(policy);
         list l(src.size());
         size_t index = 0;
-        for (auto const &value: src) {
-            auto value_ = reinterpret_steal<object>(value_conv::cast(value, policy, parent));
+        for (auto &&value : src) {
+            auto value_ = reinterpret_steal<object>(value_conv::cast(forward_like<T>(value), policy, parent));
             if (!value_)
                 return handle();
             PyList_SET_ITEM(l.ptr(), (ssize_t) index++, value_.release().ptr()); // steals a reference
@@ -144,12 +180,15 @@ template <typename Type, typename Value> struct list_caster {
         return l.release();
     }
 
-    PYBIND11_TYPE_CASTER(Type, _("List[") + value_conv::name() + _("]"));
+    PYBIND11_TYPE_CASTER(Type, _("List[") + value_conv::name + _("]"));
 };
 
 template <typename Type, typename Alloc> struct type_caster<std::vector<Type, Alloc>>
  : list_caster<std::vector<Type, Alloc>, Type> { };
 
+template <typename Type, typename Alloc> struct type_caster<std::deque<Type, Alloc>>
+ : list_caster<std::deque<Type, Alloc>, Type> { };
+
 template <typename Type, typename Alloc> struct type_caster<std::list<Type, Alloc>>
  : list_caster<std::list<Type, Alloc>, Type> { };
 
@@ -170,26 +209,27 @@ template <typename ArrayType, typename Value, bool Resizable, size_t Size = 0> s
 
 public:
     bool load(handle src, bool convert) {
-        if (!isinstance<list>(src))
+        if (!isinstance<sequence>(src))
             return false;
-        auto l = reinterpret_borrow<list>(src);
+        auto l = reinterpret_borrow<sequence>(src);
         if (!require_size(l.size()))
             return false;
-        value_conv conv;
         size_t ctr = 0;
         for (auto it : l) {
+            value_conv conv;
             if (!conv.load(it, convert))
                 return false;
-            value[ctr++] = cast_op<Value>(conv);
+            value[ctr++] = cast_op<Value &&>(std::move(conv));
         }
         return true;
     }
 
-    static handle cast(const ArrayType &src, return_value_policy policy, handle parent) {
+    template <typename T>
+    static handle cast(T &&src, return_value_policy policy, handle parent) {
         list l(src.size());
         size_t index = 0;
-        for (auto const &value: src) {
-            auto value_ = reinterpret_steal<object>(value_conv::cast(value, policy, parent));
+        for (auto &&value : src) {
+            auto value_ = reinterpret_steal<object>(value_conv::cast(forward_like<T>(value), policy, parent));
             if (!value_)
                 return handle();
             PyList_SET_ITEM(l.ptr(), (ssize_t) index++, value_.release().ptr()); // steals a reference
@@ -197,7 +237,7 @@ template <typename ArrayType, typename Value, bool Resizable, size_t Size = 0> s
         return l.release();
     }
 
-    PYBIND11_TYPE_CASTER(ArrayType, _("List[") + value_conv::name() + _<Resizable>(_(""), _("[") + _<Size>() + _("]")) + _("]"));
+    PYBIND11_TYPE_CASTER(ArrayType, _("List[") + value_conv::name + _<Resizable>(_(""), _("[") + _<Size>() + _("]")) + _("]"));
 };
 
 template <typename Type, size_t Size> struct type_caster<std::array<Type, Size>>
@@ -222,31 +262,34 @@ template <typename Key, typename Value, typename Hash, typename Equal, typename
 template<typename T> struct optional_caster {
     using value_conv = make_caster<typename T::value_type>;
 
-    static handle cast(const T& src, return_value_policy policy, handle parent) {
+    template <typename T_>
+    static handle cast(T_ &&src, return_value_policy policy, handle parent) {
         if (!src)
             return none().inc_ref();
-        return value_conv::cast(*src, policy, parent);
+        if (!std::is_lvalue_reference<T>::value) {
+            policy = return_value_policy_override<T>::policy(policy);
+        }
+        return value_conv::cast(*std::forward<T_>(src), policy, parent);
     }
 
     bool load(handle src, bool convert) {
         if (!src) {
             return false;
         } else if (src.is_none()) {
-            value = {};  // nullopt
-            return true;
+            return true;  // default-constructed value is already empty
         }
         value_conv inner_caster;
         if (!inner_caster.load(src, convert))
             return false;
 
-        value.emplace(cast_op<typename T::value_type>(inner_caster));
+        value.emplace(cast_op<typename T::value_type &&>(std::move(inner_caster)));
         return true;
     }
 
-    PYBIND11_TYPE_CASTER(T, _("Optional[") + value_conv::name() + _("]"));
+    PYBIND11_TYPE_CASTER(T, _("Optional[") + value_conv::name + _("]"));
 };
 
-#if PYBIND11_HAS_OPTIONAL
+#if defined(PYBIND11_HAS_OPTIONAL)
 template<typename T> struct type_caster<std::optional<T>>
     : public optional_caster<std::optional<T>> {};
 
@@ -254,7 +297,7 @@ template<> struct type_caster<std::nullopt_t>
     : public void_caster<std::nullopt_t> {};
 #endif
 
-#if PYBIND11_HAS_EXP_OPTIONAL
+#if defined(PYBIND11_HAS_EXP_OPTIONAL)
 template<typename T> struct type_caster<std::experimental::optional<T>>
     : public optional_caster<std::experimental::optional<T>> {};
 
@@ -262,14 +305,83 @@ template<> struct type_caster<std::experimental::nullopt_t>
     : public void_caster<std::experimental::nullopt_t> {};
 #endif
 
-NAMESPACE_END(detail)
+/// Visit a variant and cast any found type to Python
+struct variant_caster_visitor {
+    return_value_policy policy;
+    handle parent;
+
+    using result_type = handle; // required by boost::variant in C++11
+
+    template <typename T>
+    result_type operator()(T &&src) const {
+        return make_caster<T>::cast(std::forward<T>(src), policy, parent);
+    }
+};
+
+/// Helper class which abstracts away variant's `visit` function. `std::variant` and similar
+/// `namespace::variant` types which provide a `namespace::visit()` function are handled here
+/// automatically using argument-dependent lookup. Users can provide specializations for other
+/// variant-like classes, e.g. `boost::variant` and `boost::apply_visitor`.
+template <template<typename...> class Variant>
+struct visit_helper {
+    template <typename... Args>
+    static auto call(Args &&...args) -> decltype(visit(std::forward<Args>(args)...)) {
+        return visit(std::forward<Args>(args)...);
+    }
+};
+
+/// Generic variant caster
+template <typename Variant> struct variant_caster;
+
+template <template<typename...> class V, typename... Ts>
+struct variant_caster<V<Ts...>> {
+    static_assert(sizeof...(Ts) > 0, "Variant must consist of at least one alternative.");
+
+    template <typename U, typename... Us>
+    bool load_alternative(handle src, bool convert, type_list<U, Us...>) {
+        auto caster = make_caster<U>();
+        if (caster.load(src, convert)) {
+            value = cast_op<U>(caster);
+            return true;
+        }
+        return load_alternative(src, convert, type_list<Us...>{});
+    }
+
+    bool load_alternative(handle, bool, type_list<>) { return false; }
+
+    bool load(handle src, bool convert) {
+        // Do a first pass without conversions to improve constructor resolution.
+        // E.g. `py::int_(1).cast<variant<double, int>>()` needs to fill the `int`
+        // slot of the variant. Without two-pass loading `double` would be filled
+        // because it appears first and a conversion is possible.
+        if (convert && load_alternative(src, false, type_list<Ts...>{}))
+            return true;
+        return load_alternative(src, convert, type_list<Ts...>{});
+    }
+
+    template <typename Variant>
+    static handle cast(Variant &&src, return_value_policy policy, handle parent) {
+        return visit_helper<V>::call(variant_caster_visitor{policy, parent},
+                                     std::forward<Variant>(src));
+    }
+
+    using Type = V<Ts...>;
+    PYBIND11_TYPE_CASTER(Type, _("Union[") + detail::concat(make_caster<Ts>::name...) + _("]"));
+};
+
+#if defined(PYBIND11_HAS_VARIANT)
+template <typename... Ts>
+struct type_caster<std::variant<Ts...>> : variant_caster<std::variant<Ts...>> { };
+#endif
+
+PYBIND11_NAMESPACE_END(detail)
 
 inline std::ostream &operator<<(std::ostream &os, const handle &obj) {
     os << (std::string) str(obj);
     return os;
 }
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
 
 #if defined(_MSC_VER)
 #pragma warning(pop)
diff --git a/libs/pybind/pybind11/stl_bind.h b/libs/pybind/pybind11/stl_bind.h
index 8971882203..9d8ed0c825 100644
--- a/libs/pybind/pybind11/stl_bind.h
+++ b/libs/pybind/pybind11/stl_bind.h
@@ -9,14 +9,14 @@
 
 #pragma once
 
-#include "common.h"
+#include "detail/common.h"
 #include "operators.h"
 
 #include <algorithm>
 #include <sstream>
 
-NAMESPACE_BEGIN(pybind11)
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 /* SFINAE helper class used by 'is_comparable */
 template <typename T>  struct container_traits {
@@ -66,10 +66,7 @@ template <typename, typename, typename... Args> void vector_if_insertion_operato
 template <typename, typename, typename... Args> void vector_modifiers(const Args &...) { }
 
 template<typename Vector, typename Class_>
-void vector_if_copy_constructible(enable_if_t<
-    std::is_copy_constructible<Vector>::value &&
-    std::is_copy_constructible<typename Vector::value_type>::value, Class_> &cl) {
-
+void vector_if_copy_constructible(enable_if_t<is_copy_constructible<Vector>::value, Class_> &cl) {
     cl.def(init<const Vector &>(), "Copy constructor");
 }
 
@@ -113,40 +110,77 @@ void vector_if_equal_operator(enable_if_t<is_comparable<Vector>::value, Class_>
 // (Technically, some of these (pop and __delitem__) don't actually require copyability, but it seems
 // silly to allow deletion but not insertion, so include them here too.)
 template <typename Vector, typename Class_>
-void vector_modifiers(enable_if_t<std::is_copy_constructible<typename Vector::value_type>::value, Class_> &cl) {
+void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_type>::value, Class_> &cl) {
     using T = typename Vector::value_type;
     using SizeType = typename Vector::size_type;
     using DiffType = typename Vector::difference_type;
 
+    auto wrap_i = [](DiffType i, SizeType n) {
+        if (i < 0)
+            i += n;
+        if (i < 0 || (SizeType)i >= n)
+            throw index_error();
+        return i;
+    };
+
     cl.def("append",
            [](Vector &v, const T &value) { v.push_back(value); },
            arg("x"),
            "Add an item to the end of the list");
 
-    cl.def("__init__", [](Vector &v, iterable it) {
-        new (&v) Vector();
-        try {
-            v.reserve(len(it));
-            for (handle h : it)
-               v.push_back(h.cast<T>());
-        } catch (...) {
-            v.~Vector();
-            throw;
-        }
-    });
+    cl.def(init([](iterable it) {
+        auto v = std::unique_ptr<Vector>(new Vector());
+        v->reserve(len_hint(it));
+        for (handle h : it)
+           v->push_back(h.cast<T>());
+        return v.release();
+    }));
+
+    cl.def("clear",
+        [](Vector &v) {
+            v.clear();
+        },
+        "Clear the contents"
+    );
 
     cl.def("extend",
        [](Vector &v, const Vector &src) {
-           v.reserve(v.size() + src.size());
            v.insert(v.end(), src.begin(), src.end());
        },
        arg("L"),
        "Extend the list by appending all the items in the given list"
     );
 
+    cl.def("extend",
+       [](Vector &v, iterable it) {
+           const size_t old_size = v.size();
+           v.reserve(old_size + len_hint(it));
+           try {
+               for (handle h : it) {
+                   v.push_back(h.cast<T>());
+               }
+           } catch (const cast_error &) {
+               v.erase(v.begin() + static_cast<typename Vector::difference_type>(old_size), v.end());
+               try {
+                   v.shrink_to_fit();
+               } catch (const std::exception &) {
+                   // Do nothing
+               }
+               throw;
+           }
+       },
+       arg("L"),
+       "Extend the list by appending all the items in the given list"
+    );
+
     cl.def("insert",
-        [](Vector &v, SizeType i, const T &x) {
-            v.insert(v.begin() + (DiffType) i, x);
+        [](Vector &v, DiffType i, const T &x) {
+            // Can't use wrap_i; i == v.size() is OK
+            if (i < 0)
+                i += v.size();
+            if (i < 0 || (SizeType)i > v.size())
+                throw index_error();
+            v.insert(v.begin() + i, x);
         },
         arg("i") , arg("x"),
         "Insert an item at a given position."
@@ -164,11 +198,10 @@ void vector_modifiers(enable_if_t<std::is_copy_constructible<typename Vector::va
     );
 
     cl.def("pop",
-        [](Vector &v, SizeType i) {
-            if (i >= v.size())
-                throw index_error();
-            T t = v[i];
-            v.erase(v.begin() + (DiffType) i);
+        [wrap_i](Vector &v, DiffType i) {
+            i = wrap_i(i, v.size());
+            T t = v[(SizeType) i];
+            v.erase(v.begin() + i);
             return t;
         },
         arg("i"),
@@ -176,10 +209,9 @@ void vector_modifiers(enable_if_t<std::is_copy_constructible<typename Vector::va
     );
 
     cl.def("__setitem__",
-        [](Vector &v, SizeType i, const T &t) {
-            if (i >= v.size())
-                throw index_error();
-            v[i] = t;
+        [wrap_i](Vector &v, DiffType i, const T &t) {
+            i = wrap_i(i, v.size());
+            v[(SizeType)i] = t;
         }
     );
 
@@ -191,7 +223,7 @@ void vector_modifiers(enable_if_t<std::is_copy_constructible<typename Vector::va
             if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
                 throw error_already_set();
 
-            Vector *seq = new Vector();
+            auto *seq = new Vector();
             seq->reserve((size_t) slicelength);
 
             for (size_t i=0; i<slicelength; ++i) {
@@ -222,10 +254,9 @@ void vector_modifiers(enable_if_t<std::is_copy_constructible<typename Vector::va
     );
 
     cl.def("__delitem__",
-        [](Vector &v, SizeType i) {
-            if (i >= v.size())
-                throw index_error();
-            v.erase(v.begin() + DiffType(i));
+        [wrap_i](Vector &v, DiffType i) {
+            i = wrap_i(i, v.size());
+            v.erase(v.begin() + i);
         },
         "Delete the list elements at index ``i``"
     );
@@ -261,13 +292,21 @@ template <typename Vector, typename Class_>
 void vector_accessor(enable_if_t<!vector_needs_copy<Vector>::value, Class_> &cl) {
     using T = typename Vector::value_type;
     using SizeType = typename Vector::size_type;
+    using DiffType = typename Vector::difference_type;
     using ItType   = typename Vector::iterator;
 
+    auto wrap_i = [](DiffType i, SizeType n) {
+        if (i < 0)
+            i += n;
+        if (i < 0 || (SizeType)i >= n)
+            throw index_error();
+        return i;
+    };
+
     cl.def("__getitem__",
-        [](Vector &v, SizeType i) -> T & {
-            if (i >= v.size())
-                throw index_error();
-            return v[i];
+        [wrap_i](Vector &v, DiffType i) -> T & {
+            i = wrap_i(i, v.size());
+            return v[(SizeType)i];
         },
         return_value_policy::reference_internal // ref + keepalive
     );
@@ -287,12 +326,15 @@ template <typename Vector, typename Class_>
 void vector_accessor(enable_if_t<vector_needs_copy<Vector>::value, Class_> &cl) {
     using T = typename Vector::value_type;
     using SizeType = typename Vector::size_type;
+    using DiffType = typename Vector::difference_type;
     using ItType   = typename Vector::iterator;
     cl.def("__getitem__",
-        [](const Vector &v, SizeType i) -> T {
-            if (i >= v.size())
+        [](const Vector &v, DiffType i) -> T {
+            if (i < 0 && (i += v.size()) < 0)
+                throw index_error();
+            if ((SizeType)i >= v.size())
                 throw index_error();
-            return v[i];
+            return v[(SizeType)i];
         }
     );
 
@@ -345,23 +387,30 @@ vector_buffer(Class_& cl) {
     format_descriptor<T>::format();
 
     cl.def_buffer([](Vector& v) -> buffer_info {
-        return buffer_info(v.data(), sizeof(T), format_descriptor<T>::format(), 1, {v.size()}, {sizeof(T)});
+        return buffer_info(v.data(), static_cast<ssize_t>(sizeof(T)), format_descriptor<T>::format(), 1, {v.size()}, {sizeof(T)});
     });
 
-    cl.def("__init__", [](Vector& vec, buffer buf) {
+    cl.def(init([](buffer buf) {
         auto info = buf.request();
-        if (info.ndim != 1 || info.strides[0] <= 0 || info.strides[0] % sizeof(T))
+        if (info.ndim != 1 || info.strides[0] % static_cast<ssize_t>(sizeof(T)))
             throw type_error("Only valid 1D buffers can be copied to a vector");
-        if (!detail::compare_buffer_info<T>::compare(info) || sizeof(T) != info.itemsize)
+        if (!detail::compare_buffer_info<T>::compare(info) || (ssize_t) sizeof(T) != info.itemsize)
             throw type_error("Format mismatch (Python: " + info.format + " C++: " + format_descriptor<T>::format() + ")");
-        new (&vec) Vector();
-        vec.reserve(info.shape[0]);
+
         T *p = static_cast<T*>(info.ptr);
-        auto step = info.strides[0] / sizeof(T);
+        ssize_t step = info.strides[0] / static_cast<ssize_t>(sizeof(T));
         T *end = p + info.shape[0] * step;
-        for (; p < end; p += step)
-            vec.push_back(*p);
-    });
+        if (step == 1) {
+            return Vector(p, end);
+        }
+        else {
+            Vector vec;
+            vec.reserve((size_t) info.shape[0]);
+            for (; p != end; p += step)
+                vec.push_back(*p);
+            return vec;
+        }
+    }));
 
     return;
 }
@@ -369,16 +418,22 @@ vector_buffer(Class_& cl) {
 template <typename Vector, typename Class_, typename... Args>
 enable_if_t<!detail::any_of<std::is_same<Args, buffer_protocol>...>::value> vector_buffer(Class_&) {}
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 //
 // std::vector
 //
 template <typename Vector, typename holder_type = std::unique_ptr<Vector>, typename... Args>
-class_<Vector, holder_type> bind_vector(module &m, std::string const &name, Args&&... args) {
+class_<Vector, holder_type> bind_vector(handle scope, std::string const &name, Args&&... args) {
     using Class_ = class_<Vector, holder_type>;
 
-    Class_ cl(m, name.c_str(), std::forward<Args>(args)...);
+    // If the value_type is unregistered (e.g. a converting type) or is itself registered
+    // module-local then make the vector binding module-local as well:
+    using vtype = typename Vector::value_type;
+    auto vtype_info = detail::get_type_info(typeid(vtype));
+    bool local = !vtype_info || vtype_info->module_local;
+
+    Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);
 
     // Declare the buffer interface if a buffer_protocol() is passed in
     detail::vector_buffer<Vector, Class_, Args...>(cl);
@@ -461,7 +516,7 @@ class_<Vector, holder_type> bind_vector(module &m, std::string const &name, Args
 // std::map, std::unordered_map
 //
 
-NAMESPACE_BEGIN(detail)
+PYBIND11_NAMESPACE_BEGIN(detail)
 
 /* Fallback functions */
 template <typename, typename, typename... Args> void map_if_insertion_operator(const Args &...) { }
@@ -469,7 +524,7 @@ template <typename, typename, typename... Args> void map_assignment(const Args &
 
 // Map assignment when copy-assignable: just copy the value
 template <typename Map, typename Class_>
-void map_assignment(enable_if_t<std::is_copy_assignable<typename Map::mapped_type>::value, Class_> &cl) {
+void map_assignment(enable_if_t<is_copy_assignable<typename Map::mapped_type>::value, Class_> &cl) {
     using KeyType = typename Map::key_type;
     using MappedType = typename Map::mapped_type;
 
@@ -485,8 +540,8 @@ void map_assignment(enable_if_t<std::is_copy_assignable<typename Map::mapped_typ
 // Not copy-assignable, but still copy-constructible: we can update the value by erasing and reinserting
 template<typename Map, typename Class_>
 void map_assignment(enable_if_t<
-        !std::is_copy_assignable<typename Map::mapped_type>::value &&
-        std::is_copy_constructible<typename Map::mapped_type>::value,
+        !is_copy_assignable<typename Map::mapped_type>::value &&
+        is_copy_constructible<typename Map::mapped_type>::value,
         Class_> &cl) {
     using KeyType = typename Map::key_type;
     using MappedType = typename Map::mapped_type;
@@ -527,15 +582,25 @@ template <typename Map, typename Class_> auto map_if_insertion_operator(Class_ &
 }
 
 
-NAMESPACE_END(detail)
+PYBIND11_NAMESPACE_END(detail)
 
 template <typename Map, typename holder_type = std::unique_ptr<Map>, typename... Args>
-class_<Map, holder_type> bind_map(module &m, const std::string &name, Args&&... args) {
+class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&... args) {
     using KeyType = typename Map::key_type;
     using MappedType = typename Map::mapped_type;
     using Class_ = class_<Map, holder_type>;
 
-    Class_ cl(m, name.c_str(), std::forward<Args>(args)...);
+    // If either type is a non-module-local bound type then make the map binding non-local as well;
+    // otherwise (e.g. both types are either module-local or converting) the map will be
+    // module-local.
+    auto tinfo = detail::get_type_info(typeid(MappedType));
+    bool local = !tinfo || tinfo->module_local;
+    if (local) {
+        tinfo = detail::get_type_info(typeid(KeyType));
+        local = !tinfo || tinfo->module_local;
+    }
+
+    Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);
 
     cl.def(init<>());
 
@@ -567,6 +632,15 @@ class_<Map, holder_type> bind_map(module &m, const std::string &name, Args&&...
         return_value_policy::reference_internal // ref + keepalive
     );
 
+    cl.def("__contains__",
+        [](Map &m, const KeyType &k) -> bool {
+            auto it = m.find(k);
+            if (it == m.end())
+              return false;
+           return true;
+        }
+    );
+
     // Assignment provided only if the type is copyable
     detail::map_assignment<Map, Class_>(cl);
 
@@ -575,7 +649,7 @@ class_<Map, holder_type> bind_map(module &m, const std::string &name, Args&&...
                auto it = m.find(k);
                if (it == m.end())
                    throw key_error();
-               return m.erase(it);
+               m.erase(it);
            }
     );
 
@@ -584,4 +658,4 @@ class_<Map, holder_type> bind_map(module &m, const std::string &name, Args&&...
     return cl;
 }
 
-NAMESPACE_END(pybind11)
+PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)
diff --git a/plugins/script/CMakeLists.txt b/plugins/script/CMakeLists.txt
index 92c4dbf648..7bec3fe745 100644
--- a/plugins/script/CMakeLists.txt
+++ b/plugins/script/CMakeLists.txt
@@ -26,6 +26,7 @@ add_library(script MODULE
             ScriptCommand.cpp
             ScriptingSystem.cpp
             ScriptModule.cpp)
+set_target_properties(script PROPERTIES CXX_VISIBILITY_PRESET hidden)
 target_compile_options(script PUBLIC ${SIGC_CFLAGS})
 target_include_directories(script SYSTEM PUBLIC
                            ${CMAKE_SOURCE_DIR}/libs/pybind
diff --git a/plugins/script/PythonModule.cpp b/plugins/script/PythonModule.cpp
index b5b33693da..9113a3c0b2 100644
--- a/plugins/script/PythonModule.cpp
+++ b/plugins/script/PythonModule.cpp
@@ -5,90 +5,179 @@
 #define QUOTE(x) Str(x)
 #define PYBIND11_VERSION_STR (QUOTE(PYBIND11_VERSION_MAJOR) "." QUOTE(PYBIND11_VERSION_MINOR) "." QUOTE(PYBIND11_VERSION_PATCH))
 
+#include <pybind11/embed.h>
+#include <pybind11/stl_bind.h>
 #include "itextstream.h"
 
 namespace script
 {
 
-const char* PythonModule::NAME()
+namespace
 {
-	return "darkradiant";
+    constexpr const char* ModuleName = "darkradiant";
 }
 
-py::module& PythonModule::GetModule()
+PythonModule::PythonModule() :
+    _outputWriter(false, _outputBuffer),
+    _errorWriter(true, _errorBuffer),
+    _interpreterInitialised(false)
 {
-	if (!_module)
-	{
-		_module.reset(new py::module(NAME()));
-	}
-
-	return *_module;
+    registerModule();
 }
 
-void PythonModule::RegisterToPython(const ModuleRegistrationCallback& callback)
+PythonModule::~PythonModule()
 {
-	_registrationCallback = callback;
+    _namedInterfaces.clear();
 
-        rMessage() << "Registering darkradiant module to Python using pybind11 version " << 
-            PYBIND11_VERSION_STR << std::endl;
-        
-	// Register the darkradiant module to Python
-	int result = PyImport_AppendInittab(NAME(), InitModule);
+    // Release the references to trigger the internal cleanup before Py_Finalize
+    _module.dec_ref();
+    _module.release();
 
-	if (result == -1)
-	{
-		rError() << "Could not initialise Python module" << std::endl;
-		return;
-	}
+    _globals.dec_ref();
+    _globals.release();
+
+    py::finalize_interpreter();
 }
 
-py::dict& PythonModule::GetGlobals()
+void PythonModule::initialise()
 {
-	if (!_globals)
-	{
-		_globals.reset(new py::dict);
-	}
+    py::initialize_interpreter();
+
+    try
+    {
+        // Import the darkradiant module
+        // This is triggering the call to InitModule as passed to the inittab
+        // so we need to set the static _instance pointer right before and clear it afterwards
+        _instance = this;
+
+        py::module::import(ModuleName);
+
+        // Construct the console writer interface
+        PythonConsoleWriterClass consoleWriter(_module, "PythonConsoleWriter");
+        consoleWriter.def(py::init<bool, std::string&>());
+        consoleWriter.def("write", &PythonConsoleWriter::write);
+        consoleWriter.def("flush", &PythonConsoleWriter::flush);
+
+        // Redirect stdio output to our local ConsoleWriter instances
+        py::module::import("sys").attr("stderr") = &_errorWriter;
+        py::module::import("sys").attr("stdout") = &_outputWriter;
+
+        // String vector is used in multiple places
+        py::bind_vector< std::vector<std::string> >(_module, "StringVector");
+    }
+    catch (const py::error_already_set& ex)
+    {
+        rError() << ex.what() << std::endl;
+    }
+
+    // Not needed anymore
+    _instance = nullptr;
+}
 
-	return *_globals;
+void PythonModule::registerModule()
+{
+    rMessage() << "Registering darkradiant module to Python using pybind11 version " <<
+        PYBIND11_VERSION_STR << std::endl;
+
+    // Register the darkradiant module to Python, the InitModule function
+    // will be called as soon as the module is imported
+    int result = PyImport_AppendInittab(ModuleName, InitModule);
+
+    if (result == -1)
+    {
+        rError() << "Could not initialise Python module" << std::endl;
+        return;
+    }
 }
 
-void PythonModule::Clear()
+ExecutionResultPtr PythonModule::executeString(const std::string& scriptString)
 {
-	_module.reset();
-	_globals.reset();
+    ExecutionResultPtr result = std::make_shared<ExecutionResult>();
+
+    result->errorOccurred = false;
+
+    // Clear the output buffers before starting to execute
+    _outputBuffer.clear();
+    _errorBuffer.clear();
+
+    try
+    {
+        std::string fullScript = "import " + std::string(ModuleName) + " as DR\n"
+            "from " + std::string(ModuleName) + " import *\n";
+        fullScript.append(scriptString);
+
+        // Attempt to run the specified script
+        py::eval<py::eval_statements>(fullScript, getGlobals());
+    }
+    catch (py::error_already_set& ex)
+    {
+        _errorBuffer.append(ex.what());
+        result->errorOccurred = true;
+
+        rError() << "Error executing script: " << ex.what() << std::endl;
+    }
+
+    result->output += _outputBuffer + "\n";
+    result->output += _errorBuffer + "\n";
+
+    _outputBuffer.clear();
+    _errorBuffer.clear();
+
+    return result;
+}
+
+py::dict& PythonModule::getGlobals()
+{
+    return _globals;
 }
 
 #if PY_MAJOR_VERSION >= 3
 PyObject* PythonModule::InitModule()
 {
-	return InitModuleImpl();
+    if (!_instance) throw new std::runtime_error("_instance reference not set");
+	return _instance->initialiseModule();
 }
 #else
 void PythonModule::InitModule()
 {
-	InitModuleImpl();
+    if (!_instance) throw new std::runtime_error("_instance reference not set");
+    _instance->initialiseModule();
 }
 #endif
 
-PyObject* PythonModule::InitModuleImpl()
+PyObject* PythonModule::initialiseModule()
 {
 	try
 	{
-		// Acquire modules here (through callback?)
-		if (_registrationCallback)
-		{
-			_registrationCallback(GetModule(), GetGlobals());
-		}
-
-		py::object main = py::module::import("__main__");
-		py::dict globals = main.attr("__dict__").cast<py::dict>();
+        static py::module::module_def _moduleDef;
+        _module = py::module::create_extension_module(ModuleName, "DarkRadiant Main Module", &_moduleDef);
+
+        // Add the registered interfaces
+        for (const auto& i : _namedInterfaces)
+        {
+            // Handle each interface in its own try/catch block
+            try
+            {
+                i.second->registerInterface(_module, getGlobals());
+            }
+            catch (const py::error_already_set& ex)
+            {
+                rError() << "Error while initialising interface " << i.first << ": " << std::endl;
+                rError() << ex.what() << std::endl;
+            }
+        }
+
+		auto main = py::module::import("__main__");
+		auto globals = main.attr("__dict__").cast<py::dict>();
 
 		for (auto i = globals.begin(); i != globals.end(); ++i)
 		{
-			GetGlobals()[(*i).first] = (*i).second;
+            getGlobals()[(*i).first] = (*i).second;
 		}
 
-		return _module->ptr();
+        _interpreterInitialised = true;
+
+		return _module.ptr();
 	}
 	catch (py::error_already_set& e)
 	{
@@ -103,8 +192,39 @@ PyObject* PythonModule::InitModuleImpl()
 	}
 }
 
-std::unique_ptr<py::module> PythonModule::_module;
-std::unique_ptr<py::dict> PythonModule::_globals;
-PythonModule::ModuleRegistrationCallback PythonModule::_registrationCallback;
+void PythonModule::addInterface(const NamedInterface& iface)
+{
+    // Check if exists
+    if (interfaceExists(iface.first))
+    {
+        rError() << "A script interface with the name " << iface.first << " is already registered." << std::endl;
+        return;
+    }
+
+    // Add to the list to hold the reference
+    _namedInterfaces.emplace_back(iface);
+
+    // Initialise the interface at once, if the module is already alive
+    if (_interpreterInitialised)
+    {
+        iface.second->registerInterface(_module, getGlobals());
+    }
+}
+
+bool PythonModule::interfaceExists(const std::string& name)
+{
+    // Traverse the interface list
+    for (const auto& namedInterface : _namedInterfaces)
+    {
+        if (namedInterface.first == name)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+PythonModule* PythonModule::_instance = nullptr;
 
 }
diff --git a/plugins/script/PythonModule.h b/plugins/script/PythonModule.h
index b2f351a96f..2571b44dbd 100644
--- a/plugins/script/PythonModule.h
+++ b/plugins/script/PythonModule.h
@@ -1,37 +1,63 @@
 #pragma once
 
+#include "iscript.h"
+#include "iscriptinterface.h"
 #include <functional>
 #include <memory>
 #include <pybind11/pybind11.h>
 
+#include "PythonConsoleWriter.h"
+
 namespace py = pybind11;
 
 namespace script
 {
 
-class PythonModule
+class PythonModule final
 {
 private:
-	// Python objects and initialisation stuff
-	static std::unique_ptr<py::module> _module;
-	static std::unique_ptr<py::dict> _globals;
+	// Python module and global dictionary
+	py::module _module;
+	py::dict _globals;
+
+    // List of registered interfaces
+	NamedInterfaces _namedInterfaces;
+
+    PythonModule(const PythonModule& other) = delete;
+    PythonModule& operator=(const PythonModule& other) = delete;
+
+    // We need a static reference to the current object, since 
+    // PyImport_AppendInittab doesn't allow us to pass user data
+    static PythonModule* _instance;
+
+    // Console and Error output handling
+    std::string _outputBuffer;
+    std::string _errorBuffer;
 
-	typedef std::function<void(py::module&, py::dict&)> ModuleRegistrationCallback;
-	static ModuleRegistrationCallback _registrationCallback;
+    PythonConsoleWriter _outputWriter;
+    PythonConsoleWriter _errorWriter;
+
+    bool _interpreterInitialised;
 
 public:
-	static const char* NAME();
+    PythonModule();
+    ~PythonModule();
+
+    // Starts up the interpreter, imports the darkradiant module
+    void initialise();
 
-	// Get the module object
-	static py::module& GetModule();
+    ExecutionResultPtr executeString(const std::string& scriptString);
 
-	// Get the globals
-	static py::dict& GetGlobals();
+	// Get the global object dictionary of this module
+	py::dict& getGlobals();
 
-	static void RegisterToPython(const ModuleRegistrationCallback& callback);
+    void addInterface(const NamedInterface& iface);
 
-	// Destroys the module and the globals object, no more calls to GetModule() and GetGlobals() afterwards!
-	static void Clear();
+private:
+    // Register the darkradiant module with the inittab pointing to InitModule
+    void registerModule();
+
+    bool interfaceExists(const std::string& name);
 
 	// Endpoint called by the Python interface to acquire the module
 #if PY_MAJOR_VERSION >= 3
@@ -40,8 +66,7 @@ class PythonModule
 	static void InitModule();
 #endif
 
-private:
-	static PyObject* InitModuleImpl();
+	PyObject* initialiseModule();
 };
 
 }
diff --git a/plugins/script/ScriptingSystem.cpp b/plugins/script/ScriptingSystem.cpp
index bfbd55b49e..af2e063401 100644
--- a/plugins/script/ScriptingSystem.cpp
+++ b/plugins/script/ScriptingSystem.cpp
@@ -2,17 +2,8 @@
 
 #include <pybind11/pybind11.h>
 #include <pybind11/attr.h>
-#include <pybind11/stl_bind.h>
 #include <pybind11/eval.h>
 
-#if (PYBIND11_VERSION_MAJOR > 2) || (PYBIND11_VERSION_MAJOR == 2 && PYBIND11_VERSION_MINOR >= 2)
-#define DR_PYBIND_HAS_EMBED_H
-#endif
-
-#ifdef DR_PYBIND_HAS_EMBED_H
-#include <pybind11/embed.h>
-#endif
-
 #include "i18n.h"
 #include "itextstream.h"
 #include "iradiant.h"
@@ -59,41 +50,12 @@ namespace script
 {
 
 ScriptingSystem::ScriptingSystem() :
-	_outputWriter(false, _outputBuffer),
-	_errorWriter(true, _errorBuffer),
 	_initialised(false)
 {}
 
-void ScriptingSystem::addInterface(const std::string& name, const IScriptInterfacePtr& iface) {
-	// Check if exists
-	if (interfaceExists(name)) {
-		rError() << "Cannot add script interface " << name
-			<< ", this interface is already registered." << std::endl;
-		return;
-	}
-
-	// Try to insert
-	_interfaces.push_back(NamedInterface(name, iface));
-
-	if (_initialised) 
-	{
-		// Add the interface at once, all the others are already added
-		iface->registerInterface(PythonModule::GetModule(), PythonModule::GetGlobals());
-	}
-}
-
-bool ScriptingSystem::interfaceExists(const std::string& name)
+void ScriptingSystem::addInterface(const std::string& name, const IScriptInterfacePtr& iface)
 {
-	// Traverse the interface list
-	for (const NamedInterface& i : _interfaces)
-	{
-		if (i.first == name)
-		{
-			return true;
-		}
-	}
-
-	return false;
+    _pythonModule->addInterface(NamedInterface(name, iface));
 }
 
 void ScriptingSystem::executeScriptFile(const std::string& filename)
@@ -123,7 +85,7 @@ void ScriptingSystem::executeScriptFile(const std::string& filename, bool setExe
 		}
 
 		// Attempt to run the specified script
-		py::eval_file(filePath, PythonModule::GetGlobals(), locals);
+		py::eval_file(filePath, _pythonModule->getGlobals(), locals);
 	}
     catch (std::invalid_argument& e)
     {
@@ -138,38 +100,7 @@ void ScriptingSystem::executeScriptFile(const std::string& filename, bool setExe
 
 ExecutionResultPtr ScriptingSystem::executeString(const std::string& scriptString)
 {
-	ExecutionResultPtr result = std::make_shared<ExecutionResult>();
-
-	result->errorOccurred = false;
-
-	// Clear the output buffers before starting to execute
-	_outputBuffer.clear();
-	_errorBuffer.clear();
-
-	try
-	{
-		std::string fullScript = "import " + std::string(PythonModule::NAME()) + " as DR\n"
-			"from " + std::string(PythonModule::NAME()) + " import *\n";
-		fullScript.append(scriptString);
-
-		// Attempt to run the specified script
-		py::eval<py::eval_statements>(fullScript, PythonModule::GetGlobals());
-	}
-	catch (py::error_already_set& ex)
-	{
-		_errorBuffer.append(ex.what());
-		result->errorOccurred = true;
-
-		rError() << "Error executing script: " << ex.what() << std::endl;
-	}
-
-	result->output += _outputBuffer + "\n";
-	result->output += _errorBuffer + "\n";
-
-	_outputBuffer.clear();
-	_errorBuffer.clear();
-
-	return result;
+    return _pythonModule->executeString(scriptString);
 }
 
 void ScriptingSystem::foreachScriptCommand(const std::function<void(const IScriptCommand&)>& functor)
@@ -187,57 +118,10 @@ sigc::signal<void>& ScriptingSystem::signal_onScriptsReloaded()
 	return _sigScriptsReloaded;
 }
 
-void ScriptingSystem::addInterfacesToModule(py::module& mod, py::dict& globals)
-{
-	// Add the registered interfaces
-	for (NamedInterface& i : _interfaces)
-	{
-		// Handle each interface in its own try/catch block
-		try
-		{
-			i.second->registerInterface(mod, globals);
-		}
-		catch (const py::error_already_set& ex)
-		{
-			rError() << "Error while initialising interface " << i.first << ": " << std::endl;
-			rError() << ex.what() << std::endl;
-		}
-	}
-}
-
 void ScriptingSystem::initialise()
 {
-	// The finalize_interpreter() function is not available in older versions
-#ifdef DR_PYBIND_HAS_EMBED_H
-	py::initialize_interpreter();
-#else
-	Py_Initialize();
-#endif
-
-	{
-		try
-		{
-			// Import the darkradiant module
-			py::module::import(PythonModule::NAME());
-
-			// Construct the console writer interface
-			PythonConsoleWriterClass consoleWriter(PythonModule::GetModule(), "PythonConsoleWriter");
-			consoleWriter.def(py::init<bool, std::string&>());
-			consoleWriter.def("write", &PythonConsoleWriter::write);
-			consoleWriter.def("flush", &PythonConsoleWriter::flush);
-
-			// Redirect stdio output to our local ConsoleWriter instances
-			py::module::import("sys").attr("stderr") = &_errorWriter;
-			py::module::import("sys").attr("stdout") = &_outputWriter;
-
-			// String vector is used in multiple places
-			py::bind_vector< std::vector<std::string> >(PythonModule::GetModule(), "StringVector");
-		}
-		catch (const py::error_already_set& ex)
-		{
-			rError() << ex.what() << std::endl;
-		}
-	}
+    // Fire up the interpreter
+    _pythonModule->initialise();
 
 	_initialised = true;
 
@@ -303,7 +187,7 @@ void ScriptingSystem::loadCommandScript(const std::string& scriptFilename)
 		locals["__executeCommand__"] = false;
 
 		// Attempt to run the specified script
-		py::eval_file(_scriptPath + scriptFilename, PythonModule::GetGlobals(), locals);
+		py::eval_file(_scriptPath + scriptFilename, _pythonModule->getGlobals(), locals);
 
 		std::string cmdName;
 		std::string cmdDisplayName;
@@ -422,9 +306,8 @@ void ScriptingSystem::initialiseModule(const IApplicationContext& ctx)
 	_scriptPath = ctx.getRuntimeDataPath() + "scripts/";
 #endif
 
-	// When Python asks for the object, let's register our interfaces to the py::module
-	PythonModule::RegisterToPython(
-		std::bind(&ScriptingSystem::addInterfacesToModule, this, std::placeholders::_1, std::placeholders::_2));
+	// Set up the python interpreter
+    _pythonModule.reset(new PythonModule);
 
 	// Add the built-in interfaces (the order is important, as we don't have dependency-resolution yet)
 	addInterface("Math", std::make_shared<MathInterface>());
@@ -486,17 +369,7 @@ void ScriptingSystem::shutdownModule()
 
 	_scriptPath.clear();
 
-	// Free all interfaces
-	_interfaces.clear();
-
-	PythonModule::Clear();
-
-	// The finalize_interpreter() function is not available in older versions
-#ifdef DR_PYBIND_HAS_EMBED_H
-	py::finalize_interpreter();
-#else 
-	Py_Finalize();
-#endif
+    _pythonModule.reset();
 }
 
 } // namespace script
diff --git a/plugins/script/ScriptingSystem.h b/plugins/script/ScriptingSystem.h
index 9579d8ee1b..8d0df18b54 100644
--- a/plugins/script/ScriptingSystem.h
+++ b/plugins/script/ScriptingSystem.h
@@ -2,17 +2,15 @@
 
 #include <map>
 #include <vector>
-#include <pybind11/pybind11.h>
 
 #include "iscript.h"
 #include "iscriptinterface.h"
 #include "PythonConsoleWriter.h"
 #include "icommandsystem.h"
+#include "PythonModule.h"
 
 #include "ScriptCommand.h"
 
-namespace py = pybind11;
-
 namespace script 
 {
 
@@ -24,17 +22,8 @@ class ScriptingSystem :
 	public IScriptingSystem
 {
 private:
-	std::string _outputBuffer;
-	std::string _errorBuffer;
-
-	PythonConsoleWriter _outputWriter;
-	PythonConsoleWriter _errorWriter;
-
 	bool _initialised;
-
-	typedef std::pair<std::string, IScriptInterfacePtr> NamedInterface;
-	typedef std::vector<NamedInterface> Interfaces;
-	Interfaces _interfaces;
+    std::unique_ptr<PythonModule> _pythonModule;
 
 	// The path where the script files are hosted
 	std::string _scriptPath;
@@ -90,10 +79,6 @@ class ScriptingSystem :
 private:
 	void executeScriptFile(const std::string& filename, bool setExecuteCommandAttr);
 
-	bool interfaceExists(const std::string& name);
-
-	void addInterfacesToModule(py::module& mod, py::dict&);
-
 	void reloadScripts();
 
 	void loadCommandScript(const std::string& scriptFilename);