1349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 2349cc55cSDimitry Andric // 3349cc55cSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4349cc55cSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5349cc55cSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6349cc55cSDimitry Andric // 7349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 8349cc55cSDimitry Andric 9349cc55cSDimitry Andric #ifndef _LIBCPP___CONCEPTS_ASSIGNABLE_H 10349cc55cSDimitry Andric #define _LIBCPP___CONCEPTS_ASSIGNABLE_H 11349cc55cSDimitry Andric 12349cc55cSDimitry Andric #include <__concepts/common_reference_with.h> 13349cc55cSDimitry Andric #include <__concepts/same_as.h> 14349cc55cSDimitry Andric #include <__config> 15bdd1243dSDimitry Andric #include <__type_traits/is_reference.h> 16bdd1243dSDimitry Andric #include <__type_traits/make_const_lvalue_ref.h> 17349cc55cSDimitry Andric #include <__utility/forward.h> 18349cc55cSDimitry Andric 19349cc55cSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20349cc55cSDimitry Andric # pragma GCC system_header 21349cc55cSDimitry Andric #endif 22349cc55cSDimitry Andric 23349cc55cSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 24349cc55cSDimitry Andric 2506c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 26349cc55cSDimitry Andric 27349cc55cSDimitry Andric // [concept.assignable] 28349cc55cSDimitry Andric 29349cc55cSDimitry Andric template <class _Lhs, class _Rhs> 30349cc55cSDimitry Andric concept assignable_from = 31349cc55cSDimitry Andric is_lvalue_reference_v<_Lhs> && 32349cc55cSDimitry Andric common_reference_with<__make_const_lvalue_ref<_Lhs>, __make_const_lvalue_ref<_Rhs>> && requires(_Lhs __lhs,_Rhs && __rhs)33349cc55cSDimitry Andric requires(_Lhs __lhs, _Rhs&& __rhs) { 34*5f757f3fSDimitry Andric { __lhs = std::forward<_Rhs>(__rhs) } -> same_as<_Lhs>; 35349cc55cSDimitry Andric }; 36349cc55cSDimitry Andric 3706c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 38349cc55cSDimitry Andric 39349cc55cSDimitry Andric _LIBCPP_END_NAMESPACE_STD 40349cc55cSDimitry Andric 41349cc55cSDimitry Andric #endif // _LIBCPP___CONCEPTS_ASSIGNABLE_H 42