STEllAR-GROUP / hpx / #882

//  Copyright (c) 2011 Thomas Heller

//  Copyright (c) 2013-2025 Hartmut Kaiser

//  Copyright (c) 2014-2019 Agustin Berge

//

//  SPDX-License-Identifier: BSL-1.0

//  Distributed under the Boost Software License, Version 1.0. (See accompanying

//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#pragma once

#include <hpx/config.hpp>

#include <hpx/functional/detail/vtable/vtable.hpp>

namespace hpx::util::detail {

    ///////////////////////////////////////////////////////////////////////////

    struct empty_function

    {

    };    // must be trivial and empty

    [[noreturn]] HPX_CORE_EXPORT void throw_bad_function_call();

    template <typename R>

    [[noreturn]] inline R throw_bad_function_call()

    {

    }

    ///////////////////////////////////////////////////////////////////////////

    // make sure the empty table instance is initialized in time, even

    // during early startup

    HPX_CXX_EXPORT template <typename Sig, bool Copyable>

    struct function_vtable;

    // NOTE: nvcc (at least CUDA 9.2 and 10.1) fails with an internal compiler

    // error ("there was an error in verifying the lgenfe output!") with this

    // enabled, so we explicitly use the fallback.

#if !defined(HPX_HAVE_CUDA)

    template <typename Sig>

    [[nodiscard]] constexpr function_vtable<Sig, true> const*

    get_empty_function_vtable() noexcept

    {

        return &vtables<function_vtable<Sig, true>, empty_function>::instance;

    }

#else

    template <typename Sig>

    [[nodiscard]] function_vtable<Sig, true> const*

    get_empty_function_vtable() noexcept

    {

        static function_vtable<Sig, true> const empty_vtable =

            function_vtable<Sig, true>(

                detail::construct_vtable<empty_function>());

        return &empty_vtable;

    }

#endif

}    // namespace hpx::util::detail