v1/__concepts/common_reference_with.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
0010 #define _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
0011
0012 #include <__concepts/convertible_to.h>
0013 #include <__concepts/same_as.h>
0014 #include <__config>
0015 #include <__type_traits/common_reference.h>
0016
0017 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0018 #  pragma GCC system_header
0019 #endif
0020
0021 _LIBCPP_BEGIN_NAMESPACE_STD
0022
0023 #if _LIBCPP_STD_VER >= 20
0024
0025 // [concept.commonref]
0026
0027 template <class _Tp, class _Up>
0028 concept common_reference_with =
0029     same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> &&
0030     convertible_to<_Tp, common_reference_t<_Tp, _Up>> && convertible_to<_Up, common_reference_t<_Tp, _Up>>;
0031
0032 #endif // _LIBCPP_STD_VER >= 20
0033
0034 _LIBCPP_END_NAMESPACE_STD
0035
0036 #endif // _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H