xref: /freebsd/contrib/llvm-project/libcxx/include/__concepts/boolean_testable.h (revision f126890ac5386406dadf7c4cfa9566cbb56537c5)
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   { !_VSTD::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