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207 lines
11 KiB
207 lines
11 KiB
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___AVAILABILITY
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#define _LIBCPP___AVAILABILITY
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#include <__config>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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// Libc++ is shipped by various vendors. In particular, it is used as a system
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// library on macOS, iOS and other Apple platforms. In order for users to be
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// able to compile a binary that is intended to be deployed to an older version
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// of a platform, Clang provides availability attributes [1]. These attributes
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// can be placed on declarations and are used to describe the life cycle of a
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// symbol in the library.
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//
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// The main goal is to ensure a compile-time error if a symbol that hasn't been
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// introduced in a previously released library is used in a program that targets
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// that previously released library. Normally, this would be a load-time error
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// when one tries to launch the program against the older library.
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//
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// For example, the filesystem library was introduced in the dylib in macOS 10.15.
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// If a user compiles on a macOS 10.15 host but targets macOS 10.13 with their
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// program, the compiler would normally not complain (because the required
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// declarations are in the headers), but the dynamic loader would fail to find
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// the symbols when actually trying to launch the program on macOS 10.13. To
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// turn this into a compile-time issue instead, declarations are annotated with
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// when they were introduced, and the compiler can produce a diagnostic if the
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// program references something that isn't available on the deployment target.
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//
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// This mechanism is general in nature, and any vendor can add their markup to
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// the library (see below). Whenever a new feature is added that requires support
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// in the shared library, a macro should be added below to mark this feature
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// as unavailable. When vendors decide to ship the feature as part of their
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// shared library, they can update the markup appropriately.
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//
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// Note that this mechanism is disabled by default in the "upstream" libc++.
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// Availability annotations are only meaningful when shipping libc++ inside
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// a platform (i.e. as a system library), and so vendors that want them should
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// turn those annotations on at CMake configuration time.
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//
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// [1]: https://clang.llvm.org/docs/AttributeReference.html#availability
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// For backwards compatibility, allow users to define _LIBCPP_DISABLE_AVAILABILITY
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// for a while.
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#if defined(_LIBCPP_DISABLE_AVAILABILITY)
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# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
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# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
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# endif
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#endif
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// Availability markup is disabled when building the library, or when the compiler
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// doesn't support the proper attributes.
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#if defined(_LIBCPP_BUILDING_LIBRARY) || \
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defined(_LIBCXXABI_BUILDING_LIBRARY) || \
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!__has_feature(attribute_availability_with_strict) || \
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!__has_feature(attribute_availability_in_templates) || \
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!__has_extension(pragma_clang_attribute_external_declaration)
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# if !defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
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# define _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS
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# endif
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#endif
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#if defined(_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
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// This controls the availability of std::shared_mutex and std::shared_timed_mutex,
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// which were added to the dylib later.
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# define _LIBCPP_AVAILABILITY_SHARED_MUTEX
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// These macros control the availability of std::bad_optional_access and
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// other exception types. These were put in the shared library to prevent
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// code bloat from every user program defining the vtable for these exception
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// types.
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# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
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# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
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# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST
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// This controls the availability of std::uncaught_exceptions().
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# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS
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// This controls the availability of the sized version of ::operator delete,
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// which was added to the dylib later.
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# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE
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// This controls the availability of the std::future_error exception.
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# define _LIBCPP_AVAILABILITY_FUTURE_ERROR
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// This controls the availability of std::type_info's vtable.
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// I can't imagine how using std::type_info can work at all if
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// this isn't supported.
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# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE
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// This controls the availability of std::locale::category members
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// (e.g. std::locale::collate), which are defined in the dylib.
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# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY
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// This controls the availability of atomic operations on std::shared_ptr
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// (e.g. `std::atomic_store(std::shared_ptr)`), which require a shared
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// lock table located in the dylib.
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# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR
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// These macros control the availability of all parts of <filesystem> that
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// depend on something in the dylib.
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# define _LIBCPP_AVAILABILITY_FILESYSTEM
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# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH
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# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP
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// This controls the availability of std::to_chars.
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# define _LIBCPP_AVAILABILITY_TO_CHARS
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// This controls the availability of the C++20 synchronization library,
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// which requires shared library support for various operations
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// (see libcxx/src/atomic.cpp).
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# define _LIBCPP_AVAILABILITY_SYNC
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#elif defined(__APPLE__)
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# define _LIBCPP_AVAILABILITY_SHARED_MUTEX \
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__attribute__((availability(macosx,strict,introduced=10.12))) \
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__attribute__((availability(ios,strict,introduced=10.0))) \
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__attribute__((availability(tvos,strict,introduced=10.0))) \
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__attribute__((availability(watchos,strict,introduced=3.0)))
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# define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS \
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__attribute__((availability(macosx,strict,introduced=10.13))) \
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__attribute__((availability(ios,strict,introduced=11.0))) \
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__attribute__((availability(tvos,strict,introduced=11.0))) \
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__attribute__((availability(watchos,strict,introduced=4.0)))
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# define _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS \
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_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
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# define _LIBCPP_AVAILABILITY_BAD_ANY_CAST \
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_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
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# define _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS \
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__attribute__((availability(macosx,strict,introduced=10.12))) \
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__attribute__((availability(ios,strict,introduced=10.0))) \
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__attribute__((availability(tvos,strict,introduced=10.0))) \
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__attribute__((availability(watchos,strict,introduced=3.0)))
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# define _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE \
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__attribute__((availability(macosx,strict,introduced=10.12))) \
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__attribute__((availability(ios,strict,introduced=10.0))) \
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__attribute__((availability(tvos,strict,introduced=10.0))) \
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__attribute__((availability(watchos,strict,introduced=3.0)))
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# define _LIBCPP_AVAILABILITY_FUTURE_ERROR \
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__attribute__((availability(ios,strict,introduced=6.0)))
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# define _LIBCPP_AVAILABILITY_TYPEINFO_VTABLE \
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__attribute__((availability(macosx,strict,introduced=10.9))) \
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__attribute__((availability(ios,strict,introduced=7.0)))
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# define _LIBCPP_AVAILABILITY_LOCALE_CATEGORY \
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__attribute__((availability(macosx,strict,introduced=10.9))) \
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__attribute__((availability(ios,strict,introduced=7.0)))
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# define _LIBCPP_AVAILABILITY_ATOMIC_SHARED_PTR \
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__attribute__((availability(macosx,strict,introduced=10.9))) \
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__attribute__((availability(ios,strict,introduced=7.0)))
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# define _LIBCPP_AVAILABILITY_FILESYSTEM \
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__attribute__((availability(macosx,strict,introduced=10.15))) \
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__attribute__((availability(ios,strict,introduced=13.0))) \
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__attribute__((availability(tvos,strict,introduced=13.0))) \
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__attribute__((availability(watchos,strict,introduced=6.0)))
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# define _LIBCPP_AVAILABILITY_FILESYSTEM_PUSH \
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_Pragma("clang attribute push(__attribute__((availability(macosx,strict,introduced=10.15))), apply_to=any(function,record))") \
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_Pragma("clang attribute push(__attribute__((availability(ios,strict,introduced=13.0))), apply_to=any(function,record))") \
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_Pragma("clang attribute push(__attribute__((availability(tvos,strict,introduced=13.0))), apply_to=any(function,record))") \
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_Pragma("clang attribute push(__attribute__((availability(watchos,strict,introduced=6.0))), apply_to=any(function,record))")
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# define _LIBCPP_AVAILABILITY_FILESYSTEM_POP \
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_Pragma("clang attribute pop") \
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_Pragma("clang attribute pop") \
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_Pragma("clang attribute pop") \
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_Pragma("clang attribute pop")
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# define _LIBCPP_AVAILABILITY_TO_CHARS \
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_LIBCPP_AVAILABILITY_FILESYSTEM
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# define _LIBCPP_AVAILABILITY_SYNC \
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__attribute__((unavailable))
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#else
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// ...New vendors can add availability markup here...
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# error "It looks like you're trying to enable vendor availability markup, but you haven't defined the corresponding macros yet!"
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#endif
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// Define availability attributes that depend on _LIBCPP_NO_EXCEPTIONS.
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// Those are defined in terms of the availability attributes above, and
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// should not be vendor-specific.
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#if defined(_LIBCPP_NO_EXCEPTIONS)
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# define _LIBCPP_AVAILABILITY_FUTURE
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# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST
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# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
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# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
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#else
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# define _LIBCPP_AVAILABILITY_FUTURE _LIBCPP_AVAILABILITY_FUTURE_ERROR
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# define _LIBCPP_AVAILABILITY_THROW_BAD_ANY_CAST _LIBCPP_AVAILABILITY_BAD_ANY_CAST
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# define _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
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# define _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS
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#endif
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#endif // _LIBCPP___AVAILABILITY
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