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__availability
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__availability
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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___AVAILABILITY
#define _LIBCPP___AVAILABILITY
#include <__config>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
// Libc++ is shipped by various vendors. In particular, it is used as a system
// library on macOS, iOS and other Apple platforms. In order for users to be
// able to compile a binary that is intended to be deployed to an older version
// of a platform, Clang provides availability attributes [1]. These attributes
// can be placed on declarations and are used to describe the life cycle of a
// symbol in the library.
//
// The main goal is to ensure a compile-time error if a symbol that hasn't been
// introduced in a previously released library is used in a program that targets
// that previously released library. Normally, this would be a load-time error
// when one tries to launch the program against the older library.
//
// For example, the filesystem library was introduced in the dylib in macOS 10.15.
// If a user compiles on a macOS 10.15 host but targets macOS 10.13 with their
// program, the compiler would normally not complain (because the required
// declarations are in the headers), but the dynamic loader would fail to find
// the symbols when actually trying to launch the program on macOS 10.13. To
// turn this into a compile-time issue instead, declarations are annotated with
// when they were introduced, and the compiler can produce a diagnostic if the
// program references something that isn't available on the deployment target.
//
// This mechanism is general in nature, and any vendor can add their markup to
// the library (see below). Whenever a new feature is added that requires support
// in the shared library, a macro should be added below to mark this feature
// as unavailable. When vendors decide to ship the feature as part of their
// shared library, they can update the markup appropriately.
//
// Furthermore, many features in the standard library have corresponding
// feature-test macros. When a feature is made unavailable on some deployment
// target, a macro should be defined to signal that it is unavailable. That
// macro can then be picked up when feature-test macros are generated (see
// generate_feature_test_macro_components.py) to make sure that feature-test
// macros don't announce a feature as being implemented if it has been marked
// as unavailable.
//
// Note that this mechanism is disabled by default in the "upstream" libc++.
// Availability annotations are only meaningful when shipping libc++ inside
// a platform (i.e. as a system library), and so vendors that want them should
// turn those annotations on at CMake configuration time.
//
// [1]: https://clang.llvm.org/docs/AttributeReference.html#availability
// For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY
// for a while.
#if defined(_LIBCPP_DISABLE_AVAILABILITY)
# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
# endif
#endif
// Availability markup is disabled when building the library, or when the compiler
// doesn't support the proper attributes.
#if defined(_LIBCPP_BUILDING_LIBRARY) || \
defined(_LIBCXXABI_BUILDING_LIBRARY) || \
!__has_feature(attribute_availability_with_strict) || \
!__has_feature(attribute_availability_in_templates) || \
!__has_extension(pragma_clang_attribute_external_declaration)
# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
# endif
#endif
#if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
// This controls the availability of std::shared_mutex and std::shared_timed_mutex,
// which were added to the dylib later.
# define _LIBCPP_AVAILABILITY_SHARED_MUTEX
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex
// These macros control the availability of std::bad_optional_access and
// other exception types. These were put in the shared library to prevent
// code bloat from every user program defining the vtable for these exception
// types.
//
// Note that when exceptions are disabled, the methods that normally throw
// these exceptions can be used even on older deployment targets, but those
// methods will abort instead of throwing.
# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST
// This controls the availability of std::uncaught_exceptions().
# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS
// This controls the availability of the sized version of ::operator delete,
// ::operator delete[], and their align_val_t variants, which were all added
// in C++17, and hence not present in early dylibs.
# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE
// This controls the availability of the std::future_error exception.
//
// Note that when exceptions are disabled, the methods that normally throw
// std::future_error can be used even on older deployment targets, but those
// methods will abort instead of throwing.
# define _LIBCPP_AVAILABILITY_FUTURE_ERROR
// This controls the availability of std::type_info's vtable.
// I can't imagine how using std::type_info can work at all if
// this isn't supported.
# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
// This controls the availability of std::locale::category members
// (e.g. std::locale::collate), which are defined in the dylib.
# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY
// This controls the availability of atomic operations on std::shared_ptr
// (e.g. `std::atomic_store(std::shared_ptr)`), which require a shared
// lock table located in the dylib.
# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
// These macros control the availability of all parts of <filesystem> that
// depend on something in the dylib.
# define _LIBCPP_AVAILABILITY_FILESYSTEM
# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH
# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
// This controls the availability of std::to_chars for integral arguments.
# define _LIBCPP_AVAILABILITY_TO_CHARS
// This controls the availability of floating-point std::to_chars functions.
// These overloads were added later than the integer overloads.
# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT
// This controls the availability of the C++20 synchronization library,
// which requires shared library support for various operations
// (see libcxx/src/atomic.cpp). This includes <barier>, <latch>,
// <semaphore>, and notification functions on std::atomic.
# define _LIBCPP_AVAILABILITY_SYNC
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
// This controls the availability of the C++20 format library.
// The library is in development and not ABI stable yet. P2216 is
// retroactively accepted in C++20. This paper contains ABI breaking
// changes.
# define _LIBCPP_AVAILABILITY_FORMAT
// # define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format
// This controls whether the std::__libcpp_assertion_handler default
// assertion handler is provided by the library.
//
// Note that when users provide their own custom assertion handler,
// it doesn't matter whether the dylib provides a default handler,
// and the availability markup can actually give a false positive
// diagnostic (it will think that no handler is provided, when in
// reality the user has provided their own).
//
// Users can pass -D_LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED
// to the compiler to tell the library to ignore the fact that the
// default handler isn't available on their deployment target. Note that
// defining this macro but failing to define a custom assertion handler
// will lead to a load-time error on back-deployment targets, so it
// should be avoided.
# define _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER
#elif defined(__APPLE__)
# define _LIBCPP_AVAILABILITY_SHARED_MUTEX \
__attribute__((availability(macos,strict,introduced=10.12))) \
__attribute__((availability(ios,strict,introduced=10.0))) \
__attribute__((availability(tvos,strict,introduced=10.0))) \
__attribute__((availability(watchos,strict,introduced=3.0)))
# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \
(defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
(defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \
(defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_mutex
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_shared_timed_mutex
# endif
// Note: bad_optional_access & friends were not introduced in the matching
// macOS and iOS versions, so the version mismatch between macOS and others
// is intended.
# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS \
__attribute__((availability(macos,strict,introduced=10.13))) \
__attribute__((availability(ios,strict,introduced=12.0))) \
__attribute__((availability(tvos,strict,introduced=12.0))) \
__attribute__((availability(watchos,strict,introduced=5.0)))
# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS \
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST \
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS \
__attribute__((availability(macos,strict,introduced=10.12))) \
__attribute__((availability(ios,strict,introduced=10.0))) \
__attribute__((availability(tvos,strict,introduced=10.0))) \
__attribute__((availability(watchos,strict,introduced=3.0)))
# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE \
__attribute__((availability(macos,strict,introduced=10.12))) \
__attribute__((availability(ios,strict,introduced=10.0))) \
__attribute__((availability(tvos,strict,introduced=10.0))) \
__attribute__((availability(watchos,strict,introduced=3.0)))
# define _LIBCPP_AVAILABILITY_FUTURE_ERROR \
__attribute__((availability(ios,strict,introduced=6.0)))
# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE \
__attribute__((availability(macos,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY \
__attribute__((availability(macos,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR \
__attribute__((availability(macos,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_FILESYSTEM \
__attribute__((availability(macos,strict,introduced=10.15))) \
__attribute__((availability(ios,strict,introduced=13.0))) \
__attribute__((availability(tvos,strict,introduced=13.0))) \
__attribute__((availability(watchos,strict,introduced=6.0)))
# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH \
_Pragma("clang attribute push(__attribute__((availability(macos,strict,introduced=10.15))), apply_to=any(function,record))") \
_Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \
_Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \
_Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))")
# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP \
_Pragma("clang attribute pop") \
_Pragma("clang attribute pop") \
_Pragma("clang attribute pop") \
_Pragma("clang attribute pop")
# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101500) || \
(defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 130000) || \
(defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 130000) || \
(defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 60000)
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_filesystem
# endif
# define _LIBCPP_AVAILABILITY_TO_CHARS \
_LIBCPP_AVAILABILITY_FILESYSTEM
# define _LIBCPP_AVAILABILITY_TO_CHARS_FLOATING_POINT \
__attribute__((unavailable))
# define _LIBCPP_AVAILABILITY_SYNC \
__attribute__((availability(macos,strict,introduced=11.0))) \
__attribute__((availability(ios,strict,introduced=14.0))) \
__attribute__((availability(tvos,strict,introduced=14.0))) \
__attribute__((availability(watchos,strict,introduced=7.0)))
# if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 110000) || \
(defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 140000) || \
(defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 140000) || \
(defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 70000)
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_atomic_wait
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_barrier
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_latch
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_semaphore
# endif
# define _LIBCPP_AVAILABILITY_FORMAT \
__attribute__((unavailable))
# define _LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format
# define _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER \
__attribute__((unavailable))
#else
// ...New vendors can add availability markup here...
# error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!"
#endif
// Define availability attributes that depend on _LIBCPP_NO_EXCEPTIONS.
// Those are defined in terms of the availability attributes above, and
// should not be vendor-specific.
#if defined(_LIBCPP_NO_EXCEPTIONS)
# define _LIBCPP_AVAILABILITY_FUTURE
# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST
# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
#else
# define _LIBCPP_AVAILABILITY_FUTURE _LIBCPP_AVAILABILITY_FUTURE_ERROR
# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST
# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
#endif
// Define the special assertion handler availability attribute, which can be silenced by
// users if they provide their own custom assertion handler. The rest of the code should
// not use the *_DEFAULT_* macro directly, since that would make it ignore the fact that
// the user provided a custom handler.
#if defined(_LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED)
# define _LIBCPP_AVAILABILITY_ASSERTION_HANDLER /* nothing */
#else
# define _LIBCPP_AVAILABILITY_ASSERTION_HANDLER _LIBCPP_AVAILABILITY_DEFAULT_ASSERTION_HANDLER
#endif
#endif // _LIBCPP___AVAILABILITY