llvm-project/libcxx/include/__concepts/common_reference_with.h

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
#define _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
#include <__concepts/convertible_to.h>
#include <__concepts/same_as.h>
#include <__config>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
// [concept.commonref]
template<class _Tp, class _Up>
concept common_reference_with =
same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> &&
convertible_to<_Tp, common_reference_t<_Tp, _Up>> &&
convertible_to<_Up, common_reference_t<_Tp, _Up>>;
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H