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___TYPE_TRAITS_IS_REFERENCEABLE_H 10 #define _LIBCPP___TYPE_TRAITS_IS_REFERENCEABLE_H 11 12 #include <__config> 13 #include <__type_traits/void_t.h> 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 template <class _Tp, class = void> 22 inline const bool __is_referenceable_v = false; 23 24 template <class _Tp> 25 inline const bool __is_referenceable_v<_Tp, __void_t<_Tp&> > = true; 26 27 #if _LIBCPP_STD_VER >= 20 28 template <class _Tp> 29 concept __referenceable = __is_referenceable_v<_Tp>; 30 #endif 31 32 _LIBCPP_END_NAMESPACE_STD 33 34 #endif // _LIBCPP___TYPE_TRAITS_IS_REFERENCEABLE_H 35