libcxx/include/__functional/is_transparent.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___FUNCTIONAL_IS_TRANSPARENT
  11 #define _LIBCPP___FUNCTIONAL_IS_TRANSPARENT
  12
  13 #include <__config>
  14 #include <type_traits>
  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 > 11
  23
  24 template <class _Tp, class, class = void>
  25 struct __is_transparent : false_type {};
  26
  27 template <class _Tp, class _Up>
  28 struct __is_transparent<_Tp, _Up,
  29                         typename __void_t<typename _Tp::is_transparent>::type>
  30    : true_type {};
  31
  32 #endif
  33
  34 _LIBCPP_END_NAMESPACE_STD
  35
  36 #endif // _LIBCPP___FUNCTIONAL_IS_TRANSPARENT