//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCUDACXX___TYPE_TRAITS_ALIGNED_UNION_H
#define _LIBCUDACXX___TYPE_TRAITS_ALIGNED_UNION_H

#ifndef __cuda_std__
#include <__config>
#endif // __cuda_std__

#include "../__type_traits/aligned_storage.h"
#include "../__type_traits/integral_constant.h"
#include "../cstddef"

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

_LIBCUDACXX_BEGIN_NAMESPACE_STD

template <size_t _I0, size_t ..._In>
struct __static_max;

template <size_t _I0>
struct __static_max<_I0>
{
    static const size_t value = _I0;
};

template <size_t _I0, size_t _I1, size_t ..._In>
struct __static_max<_I0, _I1, _In...>
{
    static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value :
                                             __static_max<_I1, _In...>::value;
};

template <size_t _Len, class _Type0, class ..._Types>
struct aligned_union
{
    static const size_t alignment_value = __static_max<_LIBCUDACXX_PREFERRED_ALIGNOF(_Type0),
                                                       _LIBCUDACXX_PREFERRED_ALIGNOF(_Types)...>::value;
    static const size_t __len = __static_max<_Len, sizeof(_Type0),
                                             sizeof(_Types)...>::value;
    typedef typename aligned_storage<__len, alignment_value>::type type;
};

#if _LIBCUDACXX_STD_VER > 11
template <size_t _Len, class ..._Types> using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
#endif

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___TYPE_TRAITS_ALIGNED_UNION_H
