xref: /openbsd-src/gnu/llvm/libcxx/include/__concepts/common_with.h (revision 4bdff4bed0e3d54e55670334c7d0077db4170f86)
1*4bdff4beSrobert //===----------------------------------------------------------------------===//
2*4bdff4beSrobert //
3*4bdff4beSrobert // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*4bdff4beSrobert // See https://llvm.org/LICENSE.txt for license information.
5*4bdff4beSrobert // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*4bdff4beSrobert //
7*4bdff4beSrobert //===----------------------------------------------------------------------===//
8*4bdff4beSrobert 
9*4bdff4beSrobert #ifndef _LIBCPP___CONCEPTS_COMMON_WITH_H
10*4bdff4beSrobert #define _LIBCPP___CONCEPTS_COMMON_WITH_H
11*4bdff4beSrobert 
12*4bdff4beSrobert #include <__concepts/common_reference_with.h>
13*4bdff4beSrobert #include <__concepts/same_as.h>
14*4bdff4beSrobert #include <__config>
15*4bdff4beSrobert #include <__type_traits/add_lvalue_reference.h>
16*4bdff4beSrobert #include <__type_traits/common_reference.h>
17*4bdff4beSrobert #include <__type_traits/common_type.h>
18*4bdff4beSrobert #include <__utility/declval.h>
19*4bdff4beSrobert 
20*4bdff4beSrobert #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21*4bdff4beSrobert #  pragma GCC system_header
22*4bdff4beSrobert #endif
23*4bdff4beSrobert 
24*4bdff4beSrobert _LIBCPP_BEGIN_NAMESPACE_STD
25*4bdff4beSrobert 
26*4bdff4beSrobert #if _LIBCPP_STD_VER > 17
27*4bdff4beSrobert 
28*4bdff4beSrobert // [concept.common]
29*4bdff4beSrobert 
30*4bdff4beSrobert template<class _Tp, class _Up>
31*4bdff4beSrobert concept common_with =
32*4bdff4beSrobert   same_as<common_type_t<_Tp, _Up>, common_type_t<_Up, _Tp>> &&
33*4bdff4beSrobert   requires {
34*4bdff4beSrobert     static_cast<common_type_t<_Tp, _Up>>(std::declval<_Tp>());
35*4bdff4beSrobert     static_cast<common_type_t<_Tp, _Up>>(std::declval<_Up>());
36*4bdff4beSrobert   } &&
37*4bdff4beSrobert   common_reference_with<
38*4bdff4beSrobert     add_lvalue_reference_t<const _Tp>,
39*4bdff4beSrobert     add_lvalue_reference_t<const _Up>> &&
40*4bdff4beSrobert   common_reference_with<
41*4bdff4beSrobert     add_lvalue_reference_t<common_type_t<_Tp, _Up>>,
42*4bdff4beSrobert     common_reference_t<
43*4bdff4beSrobert       add_lvalue_reference_t<const _Tp>,
44*4bdff4beSrobert       add_lvalue_reference_t<const _Up>>>;
45*4bdff4beSrobert 
46*4bdff4beSrobert #endif // _LIBCPP_STD_VER > 17
47*4bdff4beSrobert 
48*4bdff4beSrobert _LIBCPP_END_NAMESPACE_STD
49*4bdff4beSrobert 
50*4bdff4beSrobert #endif // _LIBCPP___CONCEPTS_COMMON_WITH_H
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