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_ASSIGNABLE_H 10 #define _LIBCPP___CONCEPTS_ASSIGNABLE_H 11 12 #include <__concepts/common_reference_with.h> 13 #include <__concepts/same_as.h> 14 #include <__config> 15 #include <__utility/forward.h> 16 #include <type_traits> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 #pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 #if !defined(_LIBCPP_HAS_NO_CONCEPTS) 25 26 // [concept.assignable] 27 28 template<class _Lhs, class _Rhs> 29 concept assignable_from = 30 is_lvalue_reference_v<_Lhs> && 31 common_reference_with<__make_const_lvalue_ref<_Lhs>, __make_const_lvalue_ref<_Rhs>> && 32 requires (_Lhs __lhs, _Rhs&& __rhs) { 33 { __lhs = _VSTD::forward<_Rhs>(__rhs) } -> same_as<_Lhs>; 34 }; 35 36 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) 37 38 _LIBCPP_END_NAMESPACE_STD 39 40 #endif // _LIBCPP___CONCEPTS_ASSIGNABLE_H 41