1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H 10 #define _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H 11 12 #include <__concepts/convertible_to.h> 13 #include <__concepts/same_as.h> 14 #include <__config> 15 #include <__type_traits/common_reference.h> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 #if _LIBCPP_STD_VER >= 20 24 25 // [concept.commonref] 26 27 template <class _Tp, class _Up> 28 concept common_reference_with = 29 same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> && 30 convertible_to<_Tp, common_reference_t<_Tp, _Up>> && convertible_to<_Up, common_reference_t<_Tp, _Up>>; 31 32 #endif // _LIBCPP_STD_VER >= 20 33 34 _LIBCPP_END_NAMESPACE_STD 35 36 #endif // _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H 37