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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.
//
// 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
// 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.
# 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,
// which was added to the dylib later.
# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE
// This controls the availability of the std::future_error exception.
# 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
// This controls the availability of std::to_chars.
# define _LIBCPP_AVAILABILITY_TO_CHARS
// This controls the availability of the C++20 synchronization library,
// which requires shared library support for various operations
// (see libcxx/src/atomic.cpp).
# define _LIBCPP_AVAILABILITY_SYNC
#elif defined(__APPLE__)
# define _LIBCPP_AVAILABILITY_SHARED_MUTEX \
__attribute__((availability(macosx,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_BAD_OPTIONAL_ACCESS \
__attribute__((availability(macosx,strict,introduced=10.13))) \
__attribute__((availability(ios,strict,introduced=11.0))) \
__attribute__((availability(tvos,strict,introduced=11.0))) \
__attribute__((availability(watchos,strict,introduced=4.0)))
# 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(macosx,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(macosx,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(macosx,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY \
__attribute__((availability(macosx,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR \
__attribute__((availability(macosx,strict,introduced=10.9))) \
__attribute__((availability(ios,strict,introduced=7.0)))
# define _LIBCPP_AVAILABILITY_FILESYSTEM \
__attribute__((availability(macosx,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(macosx,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")
# define _LIBCPP_AVAILABILITY_TO_CHARS \
_LIBCPP_AVAILABILITY_FILESYSTEM
# define _LIBCPP_AVAILABILITY_SYNC \
__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
#endif // _LIBCPP___AVAILABILITY
|
