libcxx/include/__cxx03/__concepts/derived_from.h

   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_DERIVED_FROM_H
  10 #define _LIBCPP___CONCEPTS_DERIVED_FROM_H
  11
  12 #include <__cxx03/__config>
  13 #include <__cxx03/__type_traits/is_base_of.h>
  14 #include <__cxx03/__type_traits/is_convertible.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 // [concept.derived]
  25
  26 template <class _Dp, class _Bp>
  27 concept derived_from = is_base_of_v<_Bp, _Dp> && is_convertible_v<const volatile _Dp*, const volatile _Bp*>;
  28
  29 #endif // _LIBCPP_STD_VER >= 20
  30
  31 _LIBCPP_END_NAMESPACE_STD
  32
  33 #endif // _LIBCPP___CONCEPTS_DERIVED_FROM_H