f599e7a789
This patch fixes the constrains on the __perfect_forward constructor and its call operators, which were incorrect. In particular, it makes sure that we closely follow [func.require], which basically says that we must deliver the bound arguments with the appropriate value category or make the call ill-formed, but not silently fall back to using a different value category. As a fly-by, this patch also: - Adds types __bind_front_t and __not_fn_t to make the result of calling bind_front and not_fn more opaque, and improve diagnostics for users. - Adds a bunch of tests for bind_front and remove some that are now redundant. - Adds some missing _LIBCPP_HIDE_FROM_ABI annotations. Immense thanks to @tcanens for raising awareness about this issue, and providing help with the = delete bits. Differential Revision: https://reviews.llvm.org/D107199
96 lines
4.3 KiB
C++
96 lines
4.3 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___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 = _EnableIf<
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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 = _EnableIf<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 = _EnableIf<!is_invocable_v<_Op, _Bound&..., _Args...>>>
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auto operator()(_Args&&...) & = delete;
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template <class ..._Args, class = _EnableIf<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 = _EnableIf<!is_invocable_v<_Op, _Bound const&..., _Args...>>>
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auto operator()(_Args&&...) const& = delete;
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template <class ..._Args, class = _EnableIf<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 = _EnableIf<!is_invocable_v<_Op, _Bound..., _Args...>>>
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auto operator()(_Args&&...) && = delete;
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template <class ..._Args, class = _EnableIf<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 = _EnableIf<!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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