removed superfluous nb_enum metaclass

docs/changelog.rst

@@ -5,7 +5,21 @@
 Changelog
 #########
 
-nanobind uses a `semantic versioning <http://semver.org>`__ policy.
+nanobind uses a `semantic versioning <http://semver.org>`__ policy for its API.
+It also has a separate ABI version that is *not* subject to semantic
+versioning.
+
+The ABI version is relevant whenever a type binding from one extension module
+should be visible in another (also nanobind-based) extension module. In this
+case, both modules must use the same nanobind ABI version, or they will be
+isolated from each other. Releases that don't explicitly mention an ABI version
+below inherit that of the preceding release.
+
+Version 1.2.0 (TBA)
+-------------------
+
+* Removed the superfluous ``nb_enum`` metaclass.
+* ABI version 8.
 
 Version 1.1.1 (April 6, 2023)
 -----------------------------
@@ -171,7 +185,7 @@ Version 0.2.0 (March 3, 2023)
   (commit `fe4965
   <https://github.com/wjakob/nanobind/commit/fe4965369435bf7c0925bddf610553d0bb516e27>`__).
 * Various minor fixes and improvements.
-* Internals ABI version bump.
+* ABI version 7.
 
 Version 0.1.0 (January 3, 2023)
 -------------------------------
@@ -199,7 +213,7 @@ Version 0.1.0 (January 3, 2023)
   discovered in this codebase. (commit `3b81b1
   <https://github.com/wjakob/nanobind/commit/3b81b18577e243118a659b524d4de9500a320312>`__).
 * Various minor fixes and improvements.
-* Internals ABI version bump.
+* ABI version 6.
 
 Version 0.0.9 (Nov 23, 2022)
 ----------------------------
@@ -261,7 +275,7 @@ Version 0.0.8 (Oct 27, 2022)
   extension modules in conjunction with ``typing.py`` (commit `5e11e80
   <https://github.com/wjakob/nanobind/commit/5e11e8032f777c0a34abd437dc6e84a909907c91>`__).
 * Various minor fixes and improvements.
-* Internals ABI version bump.
+* ABI version 5.
 
 Version 0.0.7 (Oct 14, 2022)
 ----------------------------

docs/faq.rst

@@ -137,7 +137,7 @@ for ``T`` that says: "ignore ``T`` and don't use a type caster to handle it".
 
 .. warning::
 
-   If your extension consistes of multiple source code files that involve
+   If your extension consists of multiple source code files that involve
    overlapping use of type casters and bindings, you are *treading on thin
    ice*. It is easy to violate the *One Definition Rule* (ODR) [`details
    <https://en.wikipedia.org/wiki/One_Definition_Rule>`_] in such a case, which

src/nb_internals.cpp

@@ -196,20 +196,6 @@ static PyType_Spec nb_type_spec = {
     /* .slots = */ nb_type_slots
 };
 
-static PyType_Slot nb_enum_slots[] = {
-    { Py_tp_base, nullptr },
-    { 0, nullptr }
-};
-
-static PyType_Spec nb_enum_spec = {
-    /*.name = */"nanobind.nb_enum",
-    /*.basicsize = */0,
-    /*.itemsize = */0,
-    /*.flags = */Py_TPFLAGS_DEFAULT,
-    /*.slots = */nb_enum_slots
-};
-
-
 #if PY_VERSION_HEX >= 0x030C0000
 static PyMemberDef nb_static_property_members[] = {
     { "__doc__", T_OBJECT, 0, 0, nullptr },
@@ -425,16 +411,12 @@ static void internals_make() {
     int tp_itemsize = (int) PyType_Type.tp_itemsize;
     int tp_basicsize = (int) PyType_Type.tp_basicsize;
 #endif
-    nb_type_spec.basicsize = nb_enum_spec.basicsize = tp_basicsize
+    nb_type_spec.basicsize = tp_basicsize
         + (int) sizeof(type_data);
-    nb_type_spec.itemsize = nb_enum_spec.itemsize = tp_itemsize;
+    nb_type_spec.itemsize = tp_itemsize;
     nb_type_slots[0].pfunc = &PyType_Type;
     internals_p->nb_type = (PyTypeObject *) PyType_FromSpec(&nb_type_spec);
 
-    // Metaclass #2 (nb_enum)
-    nb_enum_slots[0].pfunc = internals_p->nb_type;
-    internals_p->nb_enum = (PyTypeObject *) PyType_FromSpec(&nb_enum_spec);
-
     /// Static properties
  #if defined(Py_LIMITED_API)
     tp_basicsize = cast<int>(handle(&PyProperty_Type).attr("__basicsize__"));
@@ -465,7 +447,7 @@ static void internals_make() {
 
     if (!internals_p->nb_func || !internals_p->nb_method ||
         !internals_p->nb_bound_method || !internals_p->nb_type ||
-        !internals_p->nb_enum || !internals_p->nb_static_property ||
+        !internals_p->nb_static_property ||
         !internals_p->nb_ndarray)
         fail("nanobind::detail::internals_make(): type initialization failed!");
 

src/nb_internals.h

@@ -178,7 +178,7 @@ struct nb_internals {
     PyObject *nb_module;
 
     /// Registered metaclasses for nanobind classes and enumerations
-    PyTypeObject *nb_type, *nb_enum;
+    PyTypeObject *nb_type;
 
     /// Types of nanobind functions and methods
     PyTypeObject *nb_func, *nb_method, *nb_bound_method;

src/nb_type.cpp

@@ -445,8 +445,7 @@ PyObject *nb_type_new(const type_data *t) noexcept {
 
     *s++ = { 0, nullptr };
 
-    PyTypeObject *metaclass = is_enum ? internals.nb_enum
-                                      : internals.nb_type;
+    PyTypeObject *metaclass =  internals.nb_type;
 
 #if PY_VERSION_HEX >= 0x030C0000
     // Life is good, PyType_FromMetaclass() is available
@@ -785,8 +784,7 @@ bool nb_type_get(const std::type_info *cpp_type, PyObject *src, uint8_t flags,
     PyTypeObject *src_type = Py_TYPE(src);
     const std::type_info *cpp_type_src = nullptr;
     const PyTypeObject *metaclass = Py_TYPE((PyObject *) src_type);
-    const bool src_is_nb_type = metaclass == internals.nb_type ||
-                                metaclass == internals.nb_enum;
+    const bool src_is_nb_type = metaclass == internals.nb_type;
 
     type_data *dst_type = nullptr;
 
@@ -867,7 +865,7 @@ void keep_alive(PyObject *nurse, PyObject *patient) {
     nb_internals &internals = internals_get();
     PyTypeObject *metaclass = Py_TYPE((PyObject *) Py_TYPE(nurse));
 
-    if (metaclass == internals.nb_type || metaclass == internals.nb_enum) {
+    if (metaclass == internals.nb_type) {
         // Populate nanobind-internal data structures
         keep_alive_set &keep_alive = internals.keep_alive[nurse];
 
@@ -909,7 +907,7 @@ void keep_alive(PyObject *nurse, void *payload,
 
     nb_internals &internals = internals_get();
 
-    if (metaclass == internals.nb_type || metaclass == internals.nb_enum) {
+    if (metaclass == internals.nb_type) {
         keep_alive_set &keep_alive = internals.keep_alive[nurse];
         auto [it, success] = keep_alive.emplace(payload, callback);
         if (!success)
@@ -1221,8 +1219,7 @@ bool nb_type_check(PyObject *t) noexcept {
     nb_internals &internals = internals_get();
     PyTypeObject *metaclass = Py_TYPE(t);
 
-    return metaclass == internals.nb_type ||
-           metaclass == internals.nb_enum;
+    return metaclass == internals.nb_type;
 }
 
 size_t nb_type_size(PyObject *t) noexcept {