b9a2658a3e
This patch implements the forwarding to frozen C++03 headers as discussed in https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc. In the RFC, we initially proposed selecting the right headers from the Clang driver, however consensus seemed to steer towards handling this in the library itself. This patch implements that direction. At a high level, the changes basically amount to making each public header look like this: ``` // inside <vector> #ifdef _LIBCPP_CXX03_LANG # include <__cxx03/vector> #else // normal <vector> content #endif ``` In most cases, public headers are simple umbrella headers so there isn't much code in the #else branch. In other cases, the #else branch contains the actual implementation of the header.
154 lines
5.3 KiB
C++
154 lines
5.3 KiB
C++
// -*- 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_EXECUTION
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#define _LIBCPP_EXECUTION
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/*
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namespace std::execution {
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struct sequenced_policy;
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struct parallel_policy;
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struct parallel_unsequenced_policy;
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struct unsequenced_policy; // since C++20
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inline constexpr sequenced_policy seq = implementation-defined;
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inline constexpr parallel_policy par = implementation-defined;
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inline constexpr parallel_unsequenced_policy par_unseq = implementation-defined;
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inline constexpr unsequenced_policy unseq = implementation-defined; // since C++20
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}
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namespace std {
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template <class T>
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struct is_execution_policy;
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template <class T>
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inline constexpr bool is_execution_policy_v;
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}
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*/
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#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
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# include <__cxx03/execution>
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#else
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# include <__config>
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# include <__type_traits/is_execution_policy.h>
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# include <__type_traits/is_same.h>
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# include <__type_traits/remove_cvref.h>
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# include <version>
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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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# if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
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_LIBCPP_BEGIN_NAMESPACE_STD
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namespace execution {
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struct sequenced_policy {
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_LIBCPP_HIDE_FROM_ABI constexpr explicit sequenced_policy(__disable_user_instantiations_tag) {}
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sequenced_policy(const sequenced_policy&) = delete;
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sequenced_policy& operator=(const sequenced_policy&) = delete;
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};
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inline constexpr sequenced_policy seq{__disable_user_instantiations_tag{}};
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struct parallel_policy {
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_LIBCPP_HIDE_FROM_ABI constexpr explicit parallel_policy(__disable_user_instantiations_tag) {}
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parallel_policy(const parallel_policy&) = delete;
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parallel_policy& operator=(const parallel_policy&) = delete;
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};
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inline constexpr parallel_policy par{__disable_user_instantiations_tag{}};
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struct parallel_unsequenced_policy {
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_LIBCPP_HIDE_FROM_ABI constexpr explicit parallel_unsequenced_policy(__disable_user_instantiations_tag) {}
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parallel_unsequenced_policy(const parallel_unsequenced_policy&) = delete;
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parallel_unsequenced_policy& operator=(const parallel_unsequenced_policy&) = delete;
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};
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inline constexpr parallel_unsequenced_policy par_unseq{__disable_user_instantiations_tag{}};
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struct __unsequenced_policy {
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_LIBCPP_HIDE_FROM_ABI constexpr explicit __unsequenced_policy(__disable_user_instantiations_tag) {}
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__unsequenced_policy(const __unsequenced_policy&) = delete;
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__unsequenced_policy& operator=(const __unsequenced_policy&) = delete;
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};
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constexpr __unsequenced_policy __unseq{__disable_user_instantiations_tag{}};
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# if _LIBCPP_STD_VER >= 20
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struct unsequenced_policy {
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_LIBCPP_HIDE_FROM_ABI constexpr explicit unsequenced_policy(__disable_user_instantiations_tag) {}
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unsequenced_policy(const unsequenced_policy&) = delete;
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unsequenced_policy& operator=(const unsequenced_policy&) = delete;
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};
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inline constexpr unsequenced_policy unseq{__disable_user_instantiations_tag{}};
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# endif // _LIBCPP_STD_VER >= 20
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} // namespace execution
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template <>
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inline constexpr bool is_execution_policy_v<execution::sequenced_policy> = true;
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template <>
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inline constexpr bool is_execution_policy_v<execution::parallel_policy> = true;
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template <>
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inline constexpr bool is_execution_policy_v<execution::parallel_unsequenced_policy> = true;
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template <>
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inline constexpr bool is_execution_policy_v<execution::__unsequenced_policy> = true;
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template <>
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inline constexpr bool __is_parallel_execution_policy_impl<execution::parallel_policy> = true;
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template <>
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inline constexpr bool __is_parallel_execution_policy_impl<execution::parallel_unsequenced_policy> = true;
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template <>
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inline constexpr bool __is_unsequenced_execution_policy_impl<execution::__unsequenced_policy> = true;
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template <>
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inline constexpr bool __is_unsequenced_execution_policy_impl<execution::parallel_unsequenced_policy> = true;
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# if _LIBCPP_STD_VER >= 20
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template <>
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inline constexpr bool is_execution_policy_v<execution::unsequenced_policy> = true;
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template <>
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inline constexpr bool __is_unsequenced_execution_policy_impl<execution::unsequenced_policy> = true;
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# endif
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template <class _Tp>
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struct is_execution_policy : bool_constant<is_execution_policy_v<_Tp>> {};
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template <class _ExecutionPolicy>
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_LIBCPP_HIDE_FROM_ABI auto __remove_parallel_policy(const _ExecutionPolicy&) {
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if constexpr (is_same_v<_ExecutionPolicy, execution::parallel_policy>) {
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return execution::sequenced_policy(execution::__disable_user_instantiations_tag{});
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} else if constexpr (is_same_v<_ExecutionPolicy, execution::parallel_unsequenced_policy>) {
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return execution::__unsequenced_policy{execution::__disable_user_instantiations_tag{}};
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}
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}
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_LIBCPP_END_NAMESPACE_STD
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# endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
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# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
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# include <cstddef>
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# endif
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#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
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#endif // _LIBCPP_EXECUTION
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