C++23Backports.hpp

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//          Copyright Dominic (DNKpp) Koepke 2024 - 2025.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          https://www.boost.org/LICENSE_1_0.txt)
 
#ifndef MIMICPP_UTILITIES_CXX23_BACKPORTS_HPP
#define MIMICPP_UTILITIES_CXX23_BACKPORTS_HPP
 
#pragma once
 
#include "mimic++/config/Config.hpp"
 
#ifndef MIMICPP_DETAIL_IS_MODULE
    #include <type_traits>
    #include <version>
#endif
 
// GCOVR_EXCL_START
#ifdef __cpp_lib_unreachable
 
    #ifndef MIMICPP_DETAIL_IS_MODULE
        #include <utility>
    #endif
 
MIMICPP_DETAIL_MODULE_EXPORT namespace mimicpp::util
{
    using std::unreachable;
}
 
#else
 
MIMICPP_DETAIL_MODULE_EXPORT namespace mimicpp::util
{
    [[noreturn]]
    inline void unreachable()
    {
        MIMICPP_ASSERT(false, "Reached the unreachable.");
 
    // Uses compiler specific extensions if possible.
    // Even if no extension is used, undefined behavior is still raised by
    // an empty function body and the noreturn attribute.
    #if MIMICPP_DETAIL_IS_MSVC // MSVC
        __assume(false);
    #else                      // GCC, Clang
        __builtin_unreachable();
    #endif
    }
}
#endif
// GCOVR_EXCL_STOP
 
MIMICPP_DETAIL_MODULE_EXPORT namespace mimicpp::util
{
    template <typename T>
        requires std::is_enum_v<T>
    [[nodiscard]]
    constexpr std::underlying_type_t<T> to_underlying(T const value) noexcept
    {
        return static_cast<std::underlying_type_t<T>>(value);
    }
}
 
#endif