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>
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 !defined(_LIBCPP_HAS_NO_CONCEPTS)
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>> &&
31   convertible_to<_Up, common_reference_t<_Tp, _Up>>;
32 
33 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
34 
35 _LIBCPP_END_NAMESPACE_STD
36 
37 #endif // _LIBCPP___CONCEPTS_COMMON_REFERENCE_WITH_H
38