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> 15349cc55cSDimitry Andric #include <__utility/forward.h> 16349cc55cSDimitry Andric #include <type_traits> 17349cc55cSDimitry Andric 18349cc55cSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19349cc55cSDimitry Andric # pragma GCC system_header 20349cc55cSDimitry Andric #endif 21349cc55cSDimitry Andric 22349cc55cSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 23349cc55cSDimitry Andric 24*81ad6265SDimitry Andric #if _LIBCPP_STD_VER > 17 25349cc55cSDimitry Andric 26349cc55cSDimitry Andric // [concept.assignable] 27349cc55cSDimitry Andric 28349cc55cSDimitry Andric template<class _Lhs, class _Rhs> 29349cc55cSDimitry Andric concept assignable_from = 30349cc55cSDimitry Andric is_lvalue_reference_v<_Lhs> && 31349cc55cSDimitry Andric common_reference_with<__make_const_lvalue_ref<_Lhs>, __make_const_lvalue_ref<_Rhs>> && 32349cc55cSDimitry Andric requires (_Lhs __lhs, _Rhs&& __rhs) { 33349cc55cSDimitry Andric { __lhs = _VSTD::forward<_Rhs>(__rhs) } -> same_as<_Lhs>; 34349cc55cSDimitry Andric }; 35349cc55cSDimitry Andric 36*81ad6265SDimitry Andric #endif // _LIBCPP_STD_VER > 17 37349cc55cSDimitry Andric 38349cc55cSDimitry Andric _LIBCPP_END_NAMESPACE_STD 39349cc55cSDimitry Andric 40349cc55cSDimitry Andric #endif // _LIBCPP___CONCEPTS_ASSIGNABLE_H 41