libcxx/include/__new/launder.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___NEW_LAUNDER_H
  10 #define _LIBCPP___NEW_LAUNDER_H
  11
  12 #include <__config>
  13 #include <__type_traits/is_function.h>
  14 #include <__type_traits/is_void.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 template <class _Tp>
  22 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp* __launder(_Tp* __p) _NOEXCEPT {
  23   static_assert(!(is_function<_Tp>::value), "can't launder functions");
  24   static_assert(!is_void<_Tp>::value, "can't launder cv-void");
  25   return __builtin_launder(__p);
  26 }
  27
  28 #if _LIBCPP_STD_VER >= 17
  29 template <class _Tp>
  30 [[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp* launder(_Tp* __p) noexcept {
  31   return std::__launder(__p);
  32 }
  33 #endif
  34 _LIBCPP_END_NAMESPACE_STD
  35
  36 #endif // _LIBCPP___NEW_LAUNDER_H