ba87515fea
Currently, the library-internal feature test macros are only defined if the feature is not available, and always have the prefix `_LIBCPP_HAS_NO_`. This patch changes that, so that they are always defined and have the prefix `_LIBCPP_HAS_` instead. This changes the canonical use of these macros to `#if _LIBCPP_HAS_FEATURE`, which means that using an undefined macro (e.g. due to a missing include) is diagnosed now. While this is rather unlikely currently, a similar change in `<__configuration/availability.h>` caught a few bugs. This also improves readability, since it removes the double-negation of `#ifndef _LIBCPP_HAS_NO_FEATURE`. The current patch only touches the macros defined in `<__config>`. If people are happy with this approach, I'll make a follow-up PR to also change the macros defined in `<__config_site>`.
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
//===----------------------------------------------------------------------===//
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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___MUTEX_MUTEX_H
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#define _LIBCPP___MUTEX_MUTEX_H
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#include <__config>
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#include <__thread/support.h>
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#include <__type_traits/is_nothrow_constructible.h>
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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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#ifndef _LIBCPP_HAS_NO_THREADS
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_LIBCPP_BEGIN_NAMESPACE_STD
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class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_THREAD_SAFETY_ANNOTATION(capability("mutex")) mutex {
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__libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;
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public:
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR mutex() = default;
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mutex(const mutex&) = delete;
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mutex& operator=(const mutex&) = delete;
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# if _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION
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_LIBCPP_HIDE_FROM_ABI ~mutex() = default;
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# else
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~mutex() _NOEXCEPT;
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# endif
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void lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability());
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bool try_lock() _NOEXCEPT _LIBCPP_THREAD_SAFETY_ANNOTATION(try_acquire_capability(true));
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void unlock() _NOEXCEPT _LIBCPP_THREAD_SAFETY_ANNOTATION(release_capability());
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typedef __libcpp_mutex_t* native_handle_type;
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_LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__m_; }
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};
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static_assert(is_nothrow_default_constructible<mutex>::value, "the default constructor for std::mutex must be nothrow");
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_HAS_NO_THREADS
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#endif // _LIBCPP___MUTEX_MUTEX_H
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