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_CONVERTIBLE_TO_H
10 #define _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H
11 
12 #include <__config>
13 #include <type_traits>
14 
15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16 #pragma GCC system_header
17 #endif
18 
19 _LIBCPP_BEGIN_NAMESPACE_STD
20 
21 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
22 
23 // [concept.convertible]
24 
25 template<class _From, class _To>
26 concept convertible_to =
27   is_convertible_v<_From, _To> &&
requires(add_rvalue_reference_t<_From> (& __f)())28   requires (add_rvalue_reference_t<_From> (&__f)()) {
29     static_cast<_To>(__f());
30   };
31 
32 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
33 
34 _LIBCPP_END_NAMESPACE_STD
35 
36 #endif // _LIBCPP___CONCEPTS_CONVERTIBLE_TO_H
37