// Copyright (c) 2016-2020 Antony Polukhin
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_PFR_DETAIL_CAST_TO_LAYOUT_COMPATIBLE_HPP
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#define BOOST_PFR_DETAIL_CAST_TO_LAYOUT_COMPATIBLE_HPP
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#pragma once
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#include <boost/pfr/detail/config.hpp>
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#include <type_traits>
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#include <utility> // metaprogramming stuff
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#include <boost/pfr/detail/rvalue_t.hpp>
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namespace boost { namespace pfr { namespace detail {
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template <class T, class U>
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constexpr void static_assert_layout_compatible() noexcept {
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static_assert(
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std::alignment_of<T>::value == std::alignment_of<U>::value,
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"====================> Boost.PFR: Alignment check failed, probably your structure has user-defined alignment for the whole structure or for some of the fields."
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);
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static_assert(sizeof(T) == sizeof(U), "====================> Boost.PFR: Size check failed, probably your structure has bitfields or user-defined alignment.");
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}
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/// @cond
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#ifdef __GNUC__
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#define MAY_ALIAS __attribute__((__may_alias__))
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#else
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#define MAY_ALIAS
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#endif
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/// @endcond
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template <class To, class From>
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MAY_ALIAS const To& cast_to_layout_compatible(const From& val) noexcept {
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MAY_ALIAS const To* const t = reinterpret_cast<const To*>( std::addressof(val) );
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detail::static_assert_layout_compatible<To, From>();
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return *t;
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}
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template <class To, class From>
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MAY_ALIAS const volatile To& cast_to_layout_compatible(const volatile From& val) noexcept {
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MAY_ALIAS const volatile To* const t = reinterpret_cast<const volatile To*>( std::addressof(val) );
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detail::static_assert_layout_compatible<To, From>();
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return *t;
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}
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template <class To, class From>
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MAY_ALIAS volatile To& cast_to_layout_compatible(volatile From& val) noexcept {
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MAY_ALIAS volatile To* const t = reinterpret_cast<volatile To*>( std::addressof(val) );
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detail::static_assert_layout_compatible<To, From>();
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return *t;
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}
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template <class To, class From>
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MAY_ALIAS To& cast_to_layout_compatible(From& val) noexcept {
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MAY_ALIAS To* const t = reinterpret_cast<To*>( std::addressof(val) );
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detail::static_assert_layout_compatible<To, From>();
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return *t;
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}
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#ifdef BOOST_PFR_DETAIL_STRICT_RVALUE_TESTING
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template <class To, class From>
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To&& cast_to_layout_compatible(rvalue_t<From> val) noexcept = delete;
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#endif
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#undef MAY_ALIAS
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}}} // namespace boost::pfr::detail
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#endif // BOOST_PFR_DETAIL_CAST_TO_LAYOUT_COMPATIBLE_HPP
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