//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___TYPE_TRAITS_IS_DESTRUCTIBLE_H
#define _LIBCPP___TYPE_TRAITS_IS_DESTRUCTIBLE_H

#include <__config>
#include <__type_traits/integral_constant.h>
#include <__type_traits/is_function.h>
#include <__type_traits/is_reference.h>
#include <__type_traits/remove_all_extents.h>
#include <__utility/declval.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if __has_builtin(__is_destructible)

template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS _LIBCPP_NO_SPECIALIZATIONS is_destructible : _BoolConstant<__is_destructible(_Tp)> {};

#  if _LIBCPP_STD_VER >= 17
template <class _Tp>
_LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_destructible_v = __is_destructible(_Tp);
#  endif

#else // __has_builtin(__is_destructible)

//  if it's a reference, return true
//  if it's a function, return false
//  if it's   void,     return false
//  if it's an array of unknown bound, return false
//  Otherwise, return "declval<_Up&>().~_Up()" is well-formed
//    where _Up is remove_all_extents<_Tp>::type

template <class>
struct __is_destructible_apply {
  typedef int type;
};

template <typename _Tp>
struct __is_destructor_wellformed {
  template <typename _Tp1>
  static true_type __test(typename __is_destructible_apply<decltype(std::declval<_Tp1&>().~_Tp1())>::type);

  template <typename _Tp1>
  static false_type __test(...);

  static const bool value = decltype(__test<_Tp>(12))::value;
};

template <class _Tp, bool>
struct __destructible_imp;

template <class _Tp>
struct __destructible_imp<_Tp, false>
    : public integral_constant<bool, __is_destructor_wellformed<__remove_all_extents_t<_Tp> >::value> {};

template <class _Tp>
struct __destructible_imp<_Tp, true> : public true_type {};

template <class _Tp, bool>
struct __destructible_false;

template <class _Tp>
struct __destructible_false<_Tp, false> : public __destructible_imp<_Tp, is_reference<_Tp>::value> {};

template <class _Tp>
struct __destructible_false<_Tp, true> : public false_type {};

template <class _Tp>
struct is_destructible : public __destructible_false<_Tp, is_function<_Tp>::value> {};

template <class _Tp>
struct is_destructible<_Tp[]> : public false_type {};

template <>
struct is_destructible<void> : public false_type {};

#  if _LIBCPP_STD_VER >= 17
template <class _Tp>
inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
#  endif

#endif // __has_builtin(__is_destructible)

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___TYPE_TRAITS_IS_DESTRUCTIBLE_H
