libcxx/include/__bit/bit_cast.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___BIT_BIT_CAST_H
  11 #define _LIBCPP___BIT_BIT_CAST_H
  12
  13 #include <__config>
  14 #include <__type_traits/is_trivially_copyable.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 #ifndef _LIBCPP_CXX03_LANG
  23
  24 template <class _ToType, class _FromType>
  25 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI constexpr _ToType __bit_cast(const _FromType& __from) noexcept {
  26   return __builtin_bit_cast(_ToType, __from);
  27 }
  28
  29 #endif // _LIBCPP_CXX03_LANG
  30
  31 #if _LIBCPP_STD_VER >= 20
  32
  33 template <class _ToType, class _FromType>
  34   requires(sizeof(_ToType) == sizeof(_FromType) && is_trivially_copyable_v<_ToType> &&
  35            is_trivially_copyable_v<_FromType>)
  36 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _ToType bit_cast(const _FromType& __from) noexcept {
  37   return __builtin_bit_cast(_ToType, __from);
  38 }
  39
  40 #endif // _LIBCPP_STD_VER >= 20
  41
  42 _LIBCPP_END_NAMESPACE_STD
  43
  44 #endif // _LIBCPP___BIT_BIT_CAST_H