is_nothrow_destructible.hpp

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#ifndef BSL_IS_NOTHROW_DESTRUCTIBLE_HPP
#define BSL_IS_NOTHROW_DESTRUCTIBLE_HPP

#include "bool_constant.hpp"
#include "declval.hpp"
#include "is_detected.hpp"
#include "is_function.hpp"
#include "is_reference.hpp"
#include "is_scalar.hpp"
#include "is_unbounded_array.hpp"
#include "is_void.hpp"
#include "remove_all_extents.hpp"
#include "true_type.hpp"
#include "false_type.hpp"

namespace bsl
{
    namespace details
    {
        template<typename T>
        using is_nothrow_destructible_type = decltype(bsl::declval<T &>().~T());

        template<typename T>
        auto destructor_is_marked_nothrow(bsl::int32 ignored) noexcept
            -> bool_constant<noexcept(bsl::declval<T &>().~T())>;    // NOLINT

        template<typename T>
        auto destructor_is_marked_nothrow(bool ignored) noexcept -> false_type;

        template<typename T>
        [[nodiscard]] constexpr bool
        check_is_nothrow_destructible() noexcept
        {
            if (is_reference<T>::value) {
                return true;
            }

            if (is_void<T>::value || is_function<T>::value || is_unbounded_array<T>::value) {
                return false;
            }

            return is_detected<is_nothrow_destructible_type, remove_all_extents_t<T>>::value &&
                   decltype(destructor_is_marked_nothrow<remove_all_extents_t<T>>(0))::value;
        }
    }

    template<typename T>
    class is_nothrow_destructible final :    // --
        public bool_constant<details::check_is_nothrow_destructible<T>()>
    {};
}

#endif