368faacac7
This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9, which were related to the original commit). As landed, 5aaefa51 had unintended consequences on some downstream bots and didn't have proper coverage upstream due to a few subtle things. Implementing this is something we should do in libc++, however we'll first need to address a few issues listed in https://reviews.llvm.org/D106124#3349710. Differential Revision: https://reviews.llvm.org/D120683
96 lines
4.4 KiB
C++
96 lines
4.4 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___FUNCTIONAL_PERFECT_FORWARD_H
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#define _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H
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#include <__config>
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#include <__utility/declval.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#include <tuple>
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#include <type_traits>
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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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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 14
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template <class _Op, class _Indices, class ..._Bound>
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struct __perfect_forward_impl;
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template <class _Op, size_t ..._Idx, class ..._Bound>
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struct __perfect_forward_impl<_Op, index_sequence<_Idx...>, _Bound...> {
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private:
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tuple<_Bound...> __bound_;
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public:
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template <class ..._BoundArgs, class = enable_if_t<
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is_constructible_v<tuple<_Bound...>, _BoundArgs&&...>
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>>
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explicit constexpr __perfect_forward_impl(_BoundArgs&& ...__bound)
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: __bound_(_VSTD::forward<_BoundArgs>(__bound)...)
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{ }
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__perfect_forward_impl(__perfect_forward_impl const&) = default;
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__perfect_forward_impl(__perfect_forward_impl&&) = default;
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__perfect_forward_impl& operator=(__perfect_forward_impl const&) = default;
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__perfect_forward_impl& operator=(__perfect_forward_impl&&) = default;
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template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound&..., _Args...>>>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) &
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noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...)))
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-> decltype( _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...))
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{ return _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...); }
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template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound&..., _Args...>>>
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auto operator()(_Args&&...) & = delete;
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template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound const&..., _Args...>>>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const&
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noexcept(noexcept(_Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...)))
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-> decltype( _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...))
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{ return _Op()(_VSTD::get<_Idx>(__bound_)..., _VSTD::forward<_Args>(__args)...); }
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template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound const&..., _Args...>>>
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auto operator()(_Args&&...) const& = delete;
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template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound..., _Args...>>>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) &&
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noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...)))
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-> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...))
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{ return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...); }
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template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound..., _Args...>>>
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auto operator()(_Args&&...) && = delete;
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template <class ..._Args, class = enable_if_t<is_invocable_v<_Op, _Bound const..., _Args...>>>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Args&&... __args) const&&
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noexcept(noexcept(_Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...)))
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-> decltype( _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...))
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{ return _Op()(_VSTD::get<_Idx>(_VSTD::move(__bound_))..., _VSTD::forward<_Args>(__args)...); }
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template <class ..._Args, class = enable_if_t<!is_invocable_v<_Op, _Bound const..., _Args...>>>
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auto operator()(_Args&&...) const&& = delete;
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};
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// __perfect_forward implements a perfect-forwarding call wrapper as explained in [func.require].
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template <class _Op, class ..._Args>
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using __perfect_forward = __perfect_forward_impl<_Op, index_sequence_for<_Args...>, _Args...>;
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#endif // _LIBCPP_STD_VER > 14
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FUNCTIONAL_PERFECT_FORWARD_H
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