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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_BIT_CAST_H_
#define BASE_BIT_CAST_H_
#include <type_traits>
#include "base/compiler_specific.h"
#if !HAS_BUILTIN(__builtin_bit_cast)
#include <string.h> // memcpy
#endif
namespace base {
// This is C++20's std::bit_cast<>(). It morally does what
// `*reinterpret_cast<Dest*>(&source)` does, but the cast/deref pair is
// undefined behavior, while bit_cast<>() isn't.
template <class Dest, class Source>
#if HAS_BUILTIN(__builtin_bit_cast)
constexpr
#else
inline
#endif
Dest
bit_cast(const Source& source) {
#if HAS_BUILTIN(__builtin_bit_cast)
// TODO(thakis): Keep only this codepath once nacl is gone or updated.
return __builtin_bit_cast(Dest, source);
#else
static_assert(sizeof(Dest) == sizeof(Source),
"bit_cast requires source and destination to be the same size");
static_assert(std::is_trivially_copyable_v<Dest>,
"bit_cast requires the destination type to be copyable");
static_assert(std::is_trivially_copyable_v<Source>,
"bit_cast requires the source type to be copyable");
Dest dest;
memcpy(&dest, &source, sizeof(dest));
return dest;
#endif
}
} // namespace base
#endif // BASE_BIT_CAST_H_
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