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_BOOLEAN_TESTABLE_H 10 #define _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H 11 12 #include <__concepts/convertible_to.h> 13 #include <__config> 14 #include <__utility/forward.h> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 # pragma GCC system_header 18 #endif 19 20 _LIBCPP_BEGIN_NAMESPACE_STD 21 22 #if _LIBCPP_STD_VER >= 20 23 24 // [concepts.booleantestable] 25 26 template <class _Tp> 27 concept __boolean_testable_impl = convertible_to<_Tp, bool>; 28 29 template <class _Tp> 30 concept __boolean_testable = __boolean_testable_impl<_Tp> && requires(_Tp&& __t) { 31 { !std::forward<_Tp>(__t) } -> __boolean_testable_impl; 32 }; 33 34 #endif // _LIBCPP_STD_VER >= 20 35 36 _LIBCPP_END_NAMESPACE_STD 37 38 #endif // _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H 39