Remove libc++ and libc++abi 8.0.0 now that we switched to version 10.0.1

in the gnu/ directory.

1 files changed, 0 insertions, 1616 deletions

diff --git a/lib/libcxx/include/variant b/lib/libcxx/include/variant
deleted file mode 100644
index a4339de6cde..00000000000
--- a/lib/libcxx/include/variant
+++ /dev/null
@@ -1,1616 +0,0 @@
-// -*- C++ -*-
-//===------------------------------ variant -------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP_VARIANT
-#define _LIBCPP_VARIANT
-
-/*
-   variant synopsis
-
-namespace std {
-
-  // 20.7.2, class template variant
-  template <class... Types>
-  class variant {
-  public:
-
-    // 20.7.2.1, constructors
-    constexpr variant() noexcept(see below);
-    variant(const variant&);                // constexpr in C++20
-    variant(variant&&) noexcept(see below); // constexpr in C++20
-
-    template <class T> constexpr variant(T&&) noexcept(see below);
-
-    template <class T, class... Args>
-    constexpr explicit variant(in_place_type_t<T>, Args&&...);
-
-    template <class T, class U, class... Args>
-    constexpr explicit variant(
-        in_place_type_t<T>, initializer_list<U>, Args&&...);
-
-    template <size_t I, class... Args>
-    constexpr explicit variant(in_place_index_t<I>, Args&&...);
-
-    template <size_t I, class U, class... Args>
-    constexpr explicit variant(
-        in_place_index_t<I>, initializer_list<U>, Args&&...);
-
-    // 20.7.2.2, destructor
-    ~variant();
-
-    // 20.7.2.3, assignment
-    variant& operator=(const variant&);                // constexpr in C++20
-    variant& operator=(variant&&) noexcept(see below); // constexpr in C++20
-
-    template <class T> variant& operator=(T&&) noexcept(see below);
-
-    // 20.7.2.4, modifiers
-    template <class T, class... Args>
-    T& emplace(Args&&...);
-
-    template <class T, class U, class... Args>
-    T& emplace(initializer_list<U>, Args&&...);
-
-    template <size_t I, class... Args>
-    variant_alternative_t<I, variant>& emplace(Args&&...);
-
-    template <size_t I, class U, class...  Args>
-    variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...);
-
-    // 20.7.2.5, value status
-    constexpr bool valueless_by_exception() const noexcept;
-    constexpr size_t index() const noexcept;
-
-    // 20.7.2.6, swap
-    void swap(variant&) noexcept(see below);
-  };
-
-  // 20.7.3, variant helper classes
-  template <class T> struct variant_size; // undefined
-
-  template <class T>
-  inline constexpr size_t variant_size_v = variant_size<T>::value;
-
-  template <class T> struct variant_size<const T>;
-  template <class T> struct variant_size<volatile T>;
-  template <class T> struct variant_size<const volatile T>;
-
-  template <class... Types>
-  struct variant_size<variant<Types...>>;
-
-  template <size_t I, class T> struct variant_alternative; // undefined
-
-  template <size_t I, class T>
-  using variant_alternative_t = typename variant_alternative<I, T>::type;
-
-  template <size_t I, class T> struct variant_alternative<I, const T>;
-  template <size_t I, class T> struct variant_alternative<I, volatile T>;
-  template <size_t I, class T> struct variant_alternative<I, const volatile T>;
-
-  template <size_t I, class... Types>
-  struct variant_alternative<I, variant<Types...>>;
-
-  inline constexpr size_t variant_npos = -1;
-
-  // 20.7.4, value access
-  template <class T, class... Types>
-  constexpr bool holds_alternative(const variant<Types...>&) noexcept;
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>>&
-  get(variant<Types...>&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>>&&
-  get(variant<Types...>&&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>> const&
-  get(const variant<Types...>&);
-
-  template <size_t I, class... Types>
-  constexpr variant_alternative_t<I, variant<Types...>> const&&
-  get(const variant<Types...>&&);
-
-  template <class T, class...  Types>
-  constexpr T& get(variant<Types...>&);
-
-  template <class T, class... Types>
-  constexpr T&& get(variant<Types...>&&);
-
-  template <class T, class... Types>
-  constexpr const T& get(const variant<Types...>&);
-
-  template <class T, class... Types>
-  constexpr const T&& get(const variant<Types...>&&);
-
-  template <size_t I, class... Types>
-  constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
-  get_if(variant<Types...>*) noexcept;
-
-  template <size_t I, class... Types>
-  constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
-  get_if(const variant<Types...>*) noexcept;
-
-  template <class T, class... Types>
-  constexpr add_pointer_t<T>
-  get_if(variant<Types...>*) noexcept;
-
-  template <class T, class... Types>
-  constexpr add_pointer_t<const T>
-  get_if(const variant<Types...>*) noexcept;
-
-  // 20.7.5, relational operators
-  template <class... Types>
-  constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
-
-  template <class... Types>
-  constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
-
-  // 20.7.6, visitation
-  template <class Visitor, class... Variants>
-  constexpr see below visit(Visitor&&, Variants&&...);
-
-  // 20.7.7, class monostate
-  struct monostate;
-
-  // 20.7.8, monostate relational operators
-  constexpr bool operator<(monostate, monostate) noexcept;
-  constexpr bool operator>(monostate, monostate) noexcept;
-  constexpr bool operator<=(monostate, monostate) noexcept;
-  constexpr bool operator>=(monostate, monostate) noexcept;
-  constexpr bool operator==(monostate, monostate) noexcept;
-  constexpr bool operator!=(monostate, monostate) noexcept;
-
-  // 20.7.9, specialized algorithms
-  template <class... Types>
-  void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
-
-  // 20.7.10, class bad_variant_access
-  class bad_variant_access;
-
-  // 20.7.11, hash support
-  template <class T> struct hash;
-  template <class... Types> struct hash<variant<Types...>>;
-  template <> struct hash<monostate>;
-
-} // namespace std
-
-*/
-
-#include <__config>
-#include <__tuple>
-#include <array>
-#include <exception>
-#include <functional>
-#include <initializer_list>
-#include <new>
-#include <tuple>
-#include <type_traits>
-#include <utility>
-#include <limits>
-#include <version>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
-#endif
-
-_LIBCPP_PUSH_MACROS
-#include <__undef_macros>
-
-namespace std { // explicitly not using versioning namespace
-
-class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception {
-public:
-  virtual const char* what() const _NOEXCEPT;
-};
-
-} // namespace std
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-#if _LIBCPP_STD_VER > 14
-
-_LIBCPP_NORETURN
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-void __throw_bad_variant_access() {
-#ifndef _LIBCPP_NO_EXCEPTIONS
-        throw bad_variant_access();
-#else
-        _VSTD::abort();
-#endif
-}
-
-template <class... _Types>
-class _LIBCPP_TEMPLATE_VIS variant;
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_size;
-
-template <class _Tp>
-_LIBCPP_INLINE_VAR constexpr size_t variant_size_v = variant_size<_Tp>::value;
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp>
-    : variant_size<_Tp> {};
-
-template <class... _Types>
-struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>>
-    : integral_constant<size_t, sizeof...(_Types)> {};
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_alternative;
-
-template <size_t _Ip, class _Tp>
-using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp>
-    : add_const<variant_alternative_t<_Ip, _Tp>> {};
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp>
-    : add_volatile<variant_alternative_t<_Ip, _Tp>> {};
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp>
-    : add_cv<variant_alternative_t<_Ip, _Tp>> {};
-
-template <size_t _Ip, class... _Types>
-struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> {
-  static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>");
-  using type = __type_pack_element<_Ip, _Types...>;
-};
-
-_LIBCPP_INLINE_VAR constexpr size_t variant_npos = static_cast<size_t>(-1);
-
-constexpr int __choose_index_type(unsigned int __num_elem) {
-  if (__num_elem < std::numeric_limits<unsigned char>::max())
-    return 0;
-  if (__num_elem < std::numeric_limits<unsigned short>::max())
-    return 1;
-  return 2;
-}
-
-template <size_t _NumAlts>
-using __variant_index_t =
-#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
-  unsigned int;
-#else
-  std::tuple_element_t<
-      __choose_index_type(_NumAlts),
-      std::tuple<unsigned char, unsigned short, unsigned int>
-  >;
-#endif
-
-template <class _IndexType>
-constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1);
-
-namespace __find_detail {
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr size_t __find_index() {
-  constexpr bool __matches[] = {is_same_v<_Tp, _Types>...};
-  size_t __result = __not_found;
-  for (size_t __i = 0; __i < sizeof...(_Types); ++__i) {
-    if (__matches[__i]) {
-      if (__result != __not_found) {
-        return __ambiguous;
-      }
-      __result = __i;
-    }
-  }
-  return __result;
-}
-
-template <size_t _Index>
-struct __find_unambiguous_index_sfinae_impl
-    : integral_constant<size_t, _Index> {};
-
-template <>
-struct __find_unambiguous_index_sfinae_impl<__not_found> {};
-
-template <>
-struct __find_unambiguous_index_sfinae_impl<__ambiguous> {};
-
-template <class _Tp, class... _Types>
-struct __find_unambiguous_index_sfinae
-    : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {};
-
-} // namespace __find_detail
-
-namespace __variant_detail {
-
-struct __valueless_t {};
-
-enum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
-
-template <typename _Tp,
-          template <typename> class _IsTriviallyAvailable,
-          template <typename> class _IsAvailable>
-constexpr _Trait __trait =
-    _IsTriviallyAvailable<_Tp>::value
-        ? _Trait::_TriviallyAvailable
-        : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable;
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr _Trait __common_trait(initializer_list<_Trait> __traits) {
-  _Trait __result = _Trait::_TriviallyAvailable;
-  for (_Trait __t : __traits) {
-    if (static_cast<int>(__t) > static_cast<int>(__result)) {
-      __result = __t;
-    }
-  }
-  return __result;
-}
-
-template <typename... _Types>
-struct __traits {
-  static constexpr _Trait __copy_constructible_trait =
-      __common_trait({__trait<_Types,
-                              is_trivially_copy_constructible,
-                              is_copy_constructible>...});
-
-  static constexpr _Trait __move_constructible_trait =
-      __common_trait({__trait<_Types,
-                              is_trivially_move_constructible,
-                              is_move_constructible>...});
-
-  static constexpr _Trait __copy_assignable_trait = __common_trait(
-      {__copy_constructible_trait,
-       __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...});
-
-  static constexpr _Trait __move_assignable_trait = __common_trait(
-      {__move_constructible_trait,
-       __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
-
-  static constexpr _Trait __destructible_trait = __common_trait(
-      {__trait<_Types, is_trivially_destructible, is_destructible>...});
-};
-
-namespace __access {
-
-struct __union {
-  template <class _Vp>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) {
-    return _VSTD::forward<_Vp>(__v).__head;
-  }
-
-  template <class _Vp, size_t _Ip>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) {
-    return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>);
-  }
-};
-
-struct __base {
-  template <size_t _Ip, class _Vp>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto&& __get_alt(_Vp&& __v) {
-    return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data,
-                              in_place_index<_Ip>);
-  }
-};
-
-struct __variant {
-  template <size_t _Ip, class _Vp>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto&& __get_alt(_Vp&& __v) {
-    return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl);
-  }
-};
-
-} // namespace __access
-
-namespace __visitation {
-
-struct __base {
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto)
-  __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
-    constexpr auto __fdiagonal =
-        __make_fdiagonal<_Visitor&&,
-                         decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
-    return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
-                                _VSTD::forward<_Vs>(__vs).__as_base()...);
-  }
-
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
-                                              _Vs&&... __vs) {
-    constexpr auto __fmatrix =
-        __make_fmatrix<_Visitor&&,
-                       decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
-    return __at(__fmatrix, __vs.index()...)(
-        _VSTD::forward<_Visitor>(__visitor),
-        _VSTD::forward<_Vs>(__vs).__as_base()...);
-  }
-
-private:
-  template <class _Tp>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
-
-  template <class _Tp, size_t _Np, typename... _Indices>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
-                               size_t __index, _Indices... __indices) {
-    return __at(__elems[__index], __indices...);
-  }
-
-  template <class _Fp, class... _Fs>
-  static constexpr void __std_visit_visitor_return_type_check() {
-    static_assert(
-        __all<is_same_v<_Fp, _Fs>...>::value,
-        "`std::visit` requires the visitor to have a single return type.");
-  }
-
-  template <class... _Fs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_farray(_Fs&&... __fs) {
-    __std_visit_visitor_return_type_check<__uncvref_t<_Fs>...>();
-    using __result = array<common_type_t<__uncvref_t<_Fs>...>, sizeof...(_Fs)>;
-    return __result{{_VSTD::forward<_Fs>(__fs)...}};
-  }
-
-  template <std::size_t... _Is>
-  struct __dispatcher {
-    template <class _Fp, class... _Vs>
-    inline _LIBCPP_INLINE_VISIBILITY
-    static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
-        return __invoke_constexpr(
-            static_cast<_Fp>(__f),
-            __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
-    }
-  };
-
-  template <class _Fp, class... _Vs, size_t... _Is>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_dispatch(index_sequence<_Is...>) {
-    return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
-  }
-
-  template <size_t _Ip, class _Fp, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fdiagonal_impl() {
-    return __make_dispatch<_Fp, _Vs...>(
-        index_sequence<(__identity<_Vs>{}, _Ip)...>{});
-  }
-
-  template <class _Fp, class... _Vs, size_t... _Is>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
-    return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
-  }
-
-  template <class _Fp, class _Vp, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fdiagonal() {
-    constexpr size_t _Np = __uncvref_t<_Vp>::__size();
-    static_assert(__all<(_Np == __uncvref_t<_Vs>::__size())...>::value);
-    return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
-  }
-
-  template <class _Fp, class... _Vs, size_t... _Is>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
-    return __make_dispatch<_Fp, _Vs...>(__is);
-  }
-
-  template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
-                                            index_sequence<_Js...>,
-                                            _Ls... __ls) {
-    return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
-        index_sequence<_Is..., _Js>{}, __ls...)...);
-  }
-
-  template <class _Fp, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_fmatrix() {
-    return __make_fmatrix_impl<_Fp, _Vs...>(
-        index_sequence<>{}, make_index_sequence<__uncvref_t<_Vs>::__size()>{}...);
-  }
-};
-
-struct __variant {
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto)
-  __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
-    return __base::__visit_alt_at(__index,
-                                  _VSTD::forward<_Visitor>(__visitor),
-                                  _VSTD::forward<_Vs>(__vs).__impl...);
-  }
-
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
-                                              _Vs&&... __vs) {
-    return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor),
-                               _VSTD::forward<_Vs>(__vs).__impl...);
-  }
-
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto)
-  __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
-    return __visit_alt_at(
-        __index,
-        __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
-        _VSTD::forward<_Vs>(__vs)...);
-  }
-
-  template <class _Visitor, class... _Vs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
-                                                _Vs&&... __vs) {
-    return __visit_alt(
-        __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
-        _VSTD::forward<_Vs>(__vs)...);
-  }
-
-private:
-  template <class _Visitor, class... _Values>
-  static constexpr void __std_visit_exhaustive_visitor_check() {
-    static_assert(is_invocable_v<_Visitor, _Values...>,
-                  "`std::visit` requires the visitor to be exhaustive.");
-  }
-
-  template <class _Visitor>
-  struct __value_visitor {
-    template <class... _Alts>
-    inline _LIBCPP_INLINE_VISIBILITY
-    constexpr decltype(auto) operator()(_Alts&&... __alts) const {
-      __std_visit_exhaustive_visitor_check<
-          _Visitor,
-          decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
-      return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
-                                _VSTD::forward<_Alts>(__alts).__value...);
-    }
-    _Visitor&& __visitor;
-  };
-
-  template <class _Visitor>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
-    return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
-  }
-};
-
-} // namespace __visitation
-
-template <size_t _Index, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS __alt {
-  using __value_type = _Tp;
-
-  template <class... _Args>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr __alt(in_place_t, _Args&&... __args)
-      : __value(_VSTD::forward<_Args>(__args)...) {}
-
-  __value_type __value;
-};
-
-template <_Trait _DestructibleTrait, size_t _Index, class... _Types>
-union _LIBCPP_TEMPLATE_VIS __union;
-
-template <_Trait _DestructibleTrait, size_t _Index>
-union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
-
-#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor)                  \
-  template <size_t _Index, class _Tp, class... _Types>                         \
-  union _LIBCPP_TEMPLATE_VIS __union<destructible_trait,                      \
-                                      _Index,                                  \
-                                      _Tp,                                     \
-                                      _Types...> {                             \
-  public:                                                                      \
-    inline _LIBCPP_INLINE_VISIBILITY                                           \
-    explicit constexpr __union(__valueless_t) noexcept : __dummy{} {}          \
-                                                                               \
-    template <class... _Args>                                                  \
-    inline _LIBCPP_INLINE_VISIBILITY                                           \
-    explicit constexpr __union(in_place_index_t<0>, _Args&&... __args)         \
-        : __head(in_place, _VSTD::forward<_Args>(__args)...) {}                \
-                                                                               \
-    template <size_t _Ip, class... _Args>                                      \
-    inline _LIBCPP_INLINE_VISIBILITY                                           \
-    explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args)       \
-        : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \
-                                                                               \
-    __union(const __union&) = default;                                         \
-    __union(__union&&) = default;                                              \
-                                                                               \
-    destructor                                                                 \
-                                                                               \
-    __union& operator=(const __union&) = default;                              \
-    __union& operator=(__union&&) = default;                                   \
-                                                                               \
-  private:                                                                     \
-    char __dummy;                                                              \
-    __alt<_Index, _Tp> __head;                                                 \
-    __union<destructible_trait, _Index + 1, _Types...> __tail;                 \
-                                                                               \
-    friend struct __access::__union;                                           \
-  }
-
-_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
-_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
-_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;);
-
-#undef _LIBCPP_VARIANT_UNION
-
-template <_Trait _DestructibleTrait, class... _Types>
-class _LIBCPP_TEMPLATE_VIS __base {
-public:
-  using __index_t = __variant_index_t<sizeof...(_Types)>;
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr __base(__valueless_t tag) noexcept
-      : __data(tag), __index(__variant_npos<__index_t>) {}
-
-  template <size_t _Ip, class... _Args>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
-      :
-        __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...),
-        __index(_Ip) {}
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr bool valueless_by_exception() const noexcept {
-    return index() == variant_npos;
-  }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr size_t index() const noexcept {
-    return __index == __variant_npos<__index_t> ? variant_npos : __index;
-  }
-
-protected:
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr auto&& __as_base() & { return *this; }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr auto&& __as_base() && { return _VSTD::move(*this); }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr auto&& __as_base() const & { return *this; }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr auto&& __as_base() const && { return _VSTD::move(*this); }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  static constexpr size_t __size() { return sizeof...(_Types); }
-
-  __union<_DestructibleTrait, 0, _Types...> __data;
-  __index_t __index;
-
-  friend struct __access::__base;
-  friend struct __visitation::__base;
-};
-
-template <class _Traits, _Trait = _Traits::__destructible_trait>
-class _LIBCPP_TEMPLATE_VIS __destructor;
-
-#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy)    \
-  template <class... _Types>                                                   \
-  class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>,                 \
-                                           destructible_trait>                 \
-      : public __base<destructible_trait, _Types...> {                         \
-    using __base_type = __base<destructible_trait, _Types...>;                 \
-    using __index_t = typename __base_type::__index_t;                         \
-                                                                               \
-  public:                                                                      \
-    using __base_type::__base_type;                                            \
-    using __base_type::operator=;                                              \
-                                                                               \
-    __destructor(const __destructor&) = default;                               \
-    __destructor(__destructor&&) = default;                                    \
-    destructor                                                                 \
-    __destructor& operator=(const __destructor&) = default;                    \
-    __destructor& operator=(__destructor&&) = default;                         \
-                                                                               \
-  protected:                                                                   \
-    inline _LIBCPP_INLINE_VISIBILITY                                           \
-    destroy                                                                    \
-  }
-
-_LIBCPP_VARIANT_DESTRUCTOR(
-    _Trait::_TriviallyAvailable,
-    ~__destructor() = default;,
-    void __destroy() noexcept { this->__index = __variant_npos<__index_t>; });
-
-_LIBCPP_VARIANT_DESTRUCTOR(
-    _Trait::_Available,
-    ~__destructor() { __destroy(); },
-    void __destroy() noexcept {
-      if (!this->valueless_by_exception()) {
-        __visitation::__base::__visit_alt(
-            [](auto& __alt) noexcept {
-              using __alt_type = __uncvref_t<decltype(__alt)>;
-              __alt.~__alt_type();
-            },
-            *this);
-      }
-      this->__index = __variant_npos<__index_t>;
-    });
-
-_LIBCPP_VARIANT_DESTRUCTOR(
-    _Trait::_Unavailable,
-    ~__destructor() = delete;,
-    void __destroy() noexcept = delete;);
-
-#undef _LIBCPP_VARIANT_DESTRUCTOR
-
-template <class _Traits>
-class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> {
-  using __base_type = __destructor<_Traits>;
-
-public:
-  using __base_type::__base_type;
-  using __base_type::operator=;
-
-protected:
-  template <size_t _Ip, class _Tp, class... _Args>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
-    ::new ((void*)_VSTD::addressof(__a))
-        __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
-    return __a.__value;
-  }
-
-  template <class _Rhs>
-  inline _LIBCPP_INLINE_VISIBILITY
-  static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) {
-    __lhs.__destroy();
-    if (!__rhs.valueless_by_exception()) {
-      __visitation::__base::__visit_alt_at(
-          __rhs.index(),
-          [](auto& __lhs_alt, auto&& __rhs_alt) {
-            __construct_alt(
-                __lhs_alt,
-                _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
-          },
-          __lhs, _VSTD::forward<_Rhs>(__rhs));
-      __lhs.__index = __rhs.index();
-    }
-  }
-};
-
-template <class _Traits, _Trait = _Traits::__move_constructible_trait>
-class _LIBCPP_TEMPLATE_VIS __move_constructor;
-
-#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait,             \
-                                         move_constructor)                     \
-  template <class... _Types>                                                   \
-  class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>,          \
-                                                 move_constructible_trait>     \
-      : public __constructor<__traits<_Types...>> {                            \
-    using __base_type = __constructor<__traits<_Types...>>;                    \
-                                                                               \
-  public:                                                                      \
-    using __base_type::__base_type;                                            \
-    using __base_type::operator=;                                              \
-                                                                               \
-    __move_constructor(const __move_constructor&) = default;                   \
-    move_constructor                                                           \
-    ~__move_constructor() = default;                                           \
-    __move_constructor& operator=(const __move_constructor&) = default;        \
-    __move_constructor& operator=(__move_constructor&&) = default;             \
-  }
-
-_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
-    _Trait::_TriviallyAvailable,
-    __move_constructor(__move_constructor&& __that) = default;);
-
-_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
-    _Trait::_Available,
-    __move_constructor(__move_constructor&& __that) noexcept(
-        __all<is_nothrow_move_constructible_v<_Types>...>::value)
-        : __move_constructor(__valueless_t{}) {
-      this->__generic_construct(*this, _VSTD::move(__that));
-    });
-
-_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
-    _Trait::_Unavailable,
-    __move_constructor(__move_constructor&&) = delete;);
-
-#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
-
-template <class _Traits, _Trait = _Traits::__copy_constructible_trait>
-class _LIBCPP_TEMPLATE_VIS __copy_constructor;
-
-#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait,             \
-                                         copy_constructor)                     \
-  template <class... _Types>                                                   \
-  class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>,          \
-                                                 copy_constructible_trait>     \
-      : public __move_constructor<__traits<_Types...>> {                       \
-    using __base_type = __move_constructor<__traits<_Types...>>;               \
-                                                                               \
-  public:                                                                      \
-    using __base_type::__base_type;                                            \
-    using __base_type::operator=;                                              \
-                                                                               \
-    copy_constructor                                                           \
-    __copy_constructor(__copy_constructor&&) = default;                        \
-    ~__copy_constructor() = default;                                           \
-    __copy_constructor& operator=(const __copy_constructor&) = default;        \
-    __copy_constructor& operator=(__copy_constructor&&) = default;             \
-  }
-
-_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
-    _Trait::_TriviallyAvailable,
-    __copy_constructor(const __copy_constructor& __that) = default;);
-
-_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
-    _Trait::_Available,
-    __copy_constructor(const __copy_constructor& __that)
-        : __copy_constructor(__valueless_t{}) {
-      this->__generic_construct(*this, __that);
-    });
-
-_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
-    _Trait::_Unavailable,
-    __copy_constructor(const __copy_constructor&) = delete;);
-
-#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
-
-template <class _Traits>
-class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
-  using __base_type = __copy_constructor<_Traits>;
-
-public:
-  using __base_type::__base_type;
-  using __base_type::operator=;
-
-  template <size_t _Ip, class... _Args>
-  inline _LIBCPP_INLINE_VISIBILITY
-  auto& __emplace(_Args&&... __args) {
-    this->__destroy();
-    auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
-                          _VSTD::forward<_Args>(__args)...);
-    this->__index = _Ip;
-    return __res;
-  }
-
-protected:
-  template <size_t _Ip, class _Tp, class _Arg>
-  inline _LIBCPP_INLINE_VISIBILITY
-  void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) {
-    if (this->index() == _Ip) {
-      __a.__value = _VSTD::forward<_Arg>(__arg);
-    } else {
-      struct {
-        void operator()(true_type) const {
-          __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
-        }
-        void operator()(false_type) const {
-          __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
-        }
-        __assignment* __this;
-        _Arg&& __arg;
-      } __impl{this, _VSTD::forward<_Arg>(__arg)};
-      __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> ||
-                           !is_nothrow_move_constructible_v<_Tp>>{});
-    }
-  }
-
-  template <class _That>
-  inline _LIBCPP_INLINE_VISIBILITY
-  void __generic_assign(_That&& __that) {
-    if (this->valueless_by_exception() && __that.valueless_by_exception()) {
-      // do nothing.
-    } else if (__that.valueless_by_exception()) {
-      this->__destroy();
-    } else {
-      __visitation::__base::__visit_alt_at(
-          __that.index(),
-          [this](auto& __this_alt, auto&& __that_alt) {
-            this->__assign_alt(
-                __this_alt,
-                _VSTD::forward<decltype(__that_alt)>(__that_alt).__value);
-          },
-          *this, _VSTD::forward<_That>(__that));
-    }
-  }
-};
-
-template <class _Traits, _Trait = _Traits::__move_assignable_trait>
-class _LIBCPP_TEMPLATE_VIS __move_assignment;
-
-#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait,                 \
-                                        move_assignment)                       \
-  template <class... _Types>                                                   \
-  class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>,           \
-                                                move_assignable_trait>         \
-      : public __assignment<__traits<_Types...>> {                             \
-    using __base_type = __assignment<__traits<_Types...>>;                     \
-                                                                               \
-  public:                                                                      \
-    using __base_type::__base_type;                                            \
-    using __base_type::operator=;                                              \
-                                                                               \
-    __move_assignment(const __move_assignment&) = default;                     \
-    __move_assignment(__move_assignment&&) = default;                          \
-    ~__move_assignment() = default;                                            \
-    __move_assignment& operator=(const __move_assignment&) = default;          \
-    move_assignment                                                            \
-  }
-
-_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
-    _Trait::_TriviallyAvailable,
-    __move_assignment& operator=(__move_assignment&& __that) = default;);
-
-_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
-    _Trait::_Available,
-    __move_assignment& operator=(__move_assignment&& __that) noexcept(
-        __all<(is_nothrow_move_constructible_v<_Types> &&
-               is_nothrow_move_assignable_v<_Types>)...>::value) {
-      this->__generic_assign(_VSTD::move(__that));
-      return *this;
-    });
-
-_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
-    _Trait::_Unavailable,
-    __move_assignment& operator=(__move_assignment&&) = delete;);
-
-#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
-
-template <class _Traits, _Trait = _Traits::__copy_assignable_trait>
-class _LIBCPP_TEMPLATE_VIS __copy_assignment;
-
-#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait,                 \
-                                        copy_assignment)                       \
-  template <class... _Types>                                                   \
-  class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>,           \
-                                                copy_assignable_trait>         \
-      : public __move_assignment<__traits<_Types...>> {                        \
-    using __base_type = __move_assignment<__traits<_Types...>>;                \
-                                                                               \
-  public:                                                                      \
-    using __base_type::__base_type;                                            \
-    using __base_type::operator=;                                              \
-                                                                               \
-    __copy_assignment(const __copy_assignment&) = default;                     \
-    __copy_assignment(__copy_assignment&&) = default;                          \
-    ~__copy_assignment() = default;                                            \
-    copy_assignment                                                            \
-    __copy_assignment& operator=(__copy_assignment&&) = default;               \
-  }
-
-_LIBCPP_VARIANT_COPY_ASSIGNMENT(
-    _Trait::_TriviallyAvailable,
-    __copy_assignment& operator=(const __copy_assignment& __that) = default;);
-
-_LIBCPP_VARIANT_COPY_ASSIGNMENT(
-    _Trait::_Available,
-    __copy_assignment& operator=(const __copy_assignment& __that) {
-      this->__generic_assign(__that);
-      return *this;
-    });
-
-_LIBCPP_VARIANT_COPY_ASSIGNMENT(
-    _Trait::_Unavailable,
-    __copy_assignment& operator=(const __copy_assignment&) = delete;);
-
-#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
-
-template <class... _Types>
-class _LIBCPP_TEMPLATE_VIS __impl
-    : public __copy_assignment<__traits<_Types...>> {
-  using __base_type = __copy_assignment<__traits<_Types...>>;
-
-public:
-  using __base_type::__base_type;
-  using __base_type::operator=;
-
-  template <size_t _Ip, class _Arg>
-  inline _LIBCPP_INLINE_VISIBILITY
-  void __assign(_Arg&& __arg) {
-    this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
-                       _VSTD::forward<_Arg>(__arg));
-  }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  void __swap(__impl& __that)  {
-    if (this->valueless_by_exception() && __that.valueless_by_exception()) {
-      // do nothing.
-    } else if (this->index() == __that.index()) {
-      __visitation::__base::__visit_alt_at(
-          this->index(),
-          [](auto& __this_alt, auto& __that_alt) {
-            using _VSTD::swap;
-            swap(__this_alt.__value, __that_alt.__value);
-          },
-          *this,
-          __that);
-    } else {
-      __impl* __lhs = this;
-      __impl* __rhs = _VSTD::addressof(__that);
-      if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
-        _VSTD::swap(__lhs, __rhs);
-      }
-      __impl __tmp(_VSTD::move(*__rhs));
-#ifndef _LIBCPP_NO_EXCEPTIONS
-      // EXTENSION: When the move construction of `__lhs` into `__rhs` throws
-      // and `__tmp` is nothrow move constructible then we move `__tmp` back
-      // into `__rhs` and provide the strong exception safety guarantee.
-      try {
-        this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
-      } catch (...) {
-        if (__tmp.__move_nothrow()) {
-          this->__generic_construct(*__rhs, _VSTD::move(__tmp));
-        }
-        throw;
-      }
-#else
-      this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
-#endif
-      this->__generic_construct(*__lhs, _VSTD::move(__tmp));
-    }
-  }
-
-private:
-  inline _LIBCPP_INLINE_VISIBILITY
-  bool __move_nothrow() const {
-    constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
-    return this->valueless_by_exception() || __results[this->index()];
-  }
-};
-
-template <class... _Types>
-struct __overload;
-
-template <>
-struct __overload<> { void operator()() const; };
-
-template <class _Tp, class... _Types>
-struct __overload<_Tp, _Types...> : __overload<_Types...> {
-  using __overload<_Types...>::operator();
-  __identity<_Tp> operator()(_Tp) const;
-};
-
-template <class _Tp, class... _Types>
-using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type;
-
-} // __variant_detail
-
-template <class... _Types>
-class _LIBCPP_TEMPLATE_VIS variant
-    : private __sfinae_ctor_base<
-          __all<is_copy_constructible_v<_Types>...>::value,
-          __all<is_move_constructible_v<_Types>...>::value>,
-      private __sfinae_assign_base<
-          __all<(is_copy_constructible_v<_Types> &&
-                 is_copy_assignable_v<_Types>)...>::value,
-          __all<(is_move_constructible_v<_Types> &&
-                 is_move_assignable_v<_Types>)...>::value> {
-  static_assert(0 < sizeof...(_Types),
-                "variant must consist of at least one alternative.");
-
-  static_assert(__all<!is_array_v<_Types>...>::value,
-                "variant can not have an array type as an alternative.");
-
-  static_assert(__all<!is_reference_v<_Types>...>::value,
-                "variant can not have a reference type as an alternative.");
-
-  static_assert(__all<!is_void_v<_Types>...>::value,
-                "variant can not have a void type as an alternative.");
-
-  using __first_type = variant_alternative_t<0, variant>;
-
-public:
-  template <bool _Dummy = true,
-            enable_if_t<__dependent_type<is_default_constructible<__first_type>,
-                                         _Dummy>::value,
-                        int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
-      : __impl(in_place_index<0>) {}
-
-  variant(const variant&) = default;
-  variant(variant&&) = default;
-
-  template <
-      class _Arg,
-      enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0,
-      enable_if_t<!__is_inplace_type<__uncvref_t<_Arg>>::value, int> = 0,
-      enable_if_t<!__is_inplace_index<__uncvref_t<_Arg>>::value, int> = 0,
-      class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr variant(_Arg&& __arg) noexcept(
-      is_nothrow_constructible_v<_Tp, _Arg>)
-      : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {}
-
-  template <size_t _Ip, class... _Args,
-            class = enable_if_t<(_Ip < sizeof...(_Types)), int>,
-            class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
-            enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr variant(
-      in_place_index_t<_Ip>,
-      _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
-      : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
-
-  template <
-      size_t _Ip,
-      class _Up,
-      class... _Args,
-      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
-      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
-      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
-                  int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr variant(
-      in_place_index_t<_Ip>,
-      initializer_list<_Up> __il,
-      _Args&&... __args) noexcept(
-      is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
-      : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
-
-  template <
-      class _Tp,
-      class... _Args,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
-      is_nothrow_constructible_v<_Tp, _Args...>)
-      : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
-
-  template <
-      class _Tp,
-      class _Up,
-      class... _Args,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
-                  int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  explicit constexpr variant(
-      in_place_type_t<_Tp>,
-      initializer_list<_Up> __il,
-      _Args&&... __args) noexcept(
-      is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
-      : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
-
-  ~variant() = default;
-
-  variant& operator=(const variant&) = default;
-  variant& operator=(variant&&) = default;
-
-  template <
-      class _Arg,
-      enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0,
-      class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>,
-                  int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  variant& operator=(_Arg&& __arg) noexcept(
-      is_nothrow_assignable_v<_Tp&, _Arg> &&
-      is_nothrow_constructible_v<_Tp, _Arg>) {
-    __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg));
-    return *this;
-  }
-
-  template <
-      size_t _Ip,
-      class... _Args,
-      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
-      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
-      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  _Tp& emplace(_Args&&... __args) {
-    return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
-  }
-
-  template <
-      size_t _Ip,
-      class _Up,
-      class... _Args,
-      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
-      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
-      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
-                  int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
-    return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
-  }
-
-  template <
-      class _Tp,
-      class... _Args,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  _Tp& emplace(_Args&&... __args) {
-    return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
-  }
-
-  template <
-      class _Tp,
-      class _Up,
-      class... _Args,
-      size_t _Ip =
-          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
-      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
-                  int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
-    return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
-  }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr bool valueless_by_exception() const noexcept {
-    return __impl.valueless_by_exception();
-  }
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  constexpr size_t index() const noexcept { return __impl.index(); }
-
-  template <
-      bool _Dummy = true,
-      enable_if_t<
-          __all<(
-              __dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
-              __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
-          int> = 0>
-  inline _LIBCPP_INLINE_VISIBILITY
-  void swap(variant& __that) noexcept(
-      __all<(is_nothrow_move_constructible_v<_Types> &&
-             is_nothrow_swappable_v<_Types>)...>::value) {
-    __impl.__swap(__that.__impl);
-  }
-
-private:
-  __variant_detail::__impl<_Types...> __impl;
-
-  friend struct __variant_detail::__access::__variant;
-  friend struct __variant_detail::__visitation::__variant;
-};
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
-  return __v.index() == _Ip;
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
-  return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
-}
-
-template <size_t _Ip, class _Vp>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr auto&& __generic_get(_Vp&& __v) {
-  using __variant_detail::__access::__variant;
-  if (!__holds_alternative<_Ip>(__v)) {
-    __throw_bad_variant_access();
-  }
-  return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(
-    variant<_Types...>& __v) {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get<_Ip>(__v);
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(
-    variant<_Types...>&& __v) {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get<_Ip>(_VSTD::move(__v));
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(
-    const variant<_Types...>& __v) {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get<_Ip>(__v);
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(
-    const variant<_Types...>&& __v) {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get<_Ip>(_VSTD::move(__v));
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr _Tp& get(variant<_Types...>& __v) {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr _Tp&& get(variant<_Types...>&& __v) {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
-      _VSTD::move(__v));
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr const _Tp& get(const variant<_Types...>& __v) {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr const _Tp&& get(const variant<_Types...>&& __v) {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
-      _VSTD::move(__v));
-}
-
-template <size_t _Ip, class _Vp>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr auto* __generic_get_if(_Vp* __v) noexcept {
-  using __variant_detail::__access::__variant;
-  return __v && __holds_alternative<_Ip>(*__v)
-             ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value)
-             : nullptr;
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
-get_if(variant<_Types...>* __v) noexcept {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get_if<_Ip>(__v);
-}
-
-template <size_t _Ip, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
-get_if(const variant<_Types...>* __v) noexcept {
-  static_assert(_Ip < sizeof...(_Types));
-  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
-  return __generic_get_if<_Ip>(__v);
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr add_pointer_t<_Tp>
-get_if(variant<_Types...>* __v) noexcept {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
-}
-
-template <class _Tp, class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr add_pointer_t<const _Tp>
-get_if(const variant<_Types...>* __v) noexcept {
-  static_assert(!is_void_v<_Tp>);
-  return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
-}
-
-template <class _Operator>
-struct __convert_to_bool {
-  template <class _T1, class _T2>
-  _LIBCPP_INLINE_VISIBILITY constexpr bool operator()(_T1 && __t1, _T2&& __t2) const {
-    static_assert(std::is_convertible<decltype(_Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value,
-        "the relational operator does not return a type which is implicitly convertible to bool");
-    return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
-  }
-};
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator==(const variant<_Types...>& __lhs,
-                          const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__lhs.index() != __rhs.index()) return false;
-  if (__lhs.valueless_by_exception()) return true;
-  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs);
-}
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator!=(const variant<_Types...>& __lhs,
-                          const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__lhs.index() != __rhs.index()) return true;
-  if (__lhs.valueless_by_exception()) return false;
-  return __variant::__visit_value_at(
-      __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs);
-}
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator<(const variant<_Types...>& __lhs,
-                         const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__rhs.valueless_by_exception()) return false;
-  if (__lhs.valueless_by_exception()) return true;
-  if (__lhs.index() < __rhs.index()) return true;
-  if (__lhs.index() > __rhs.index()) return false;
-  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs);
-}
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator>(const variant<_Types...>& __lhs,
-                         const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__lhs.valueless_by_exception()) return false;
-  if (__rhs.valueless_by_exception()) return true;
-  if (__lhs.index() > __rhs.index()) return true;
-  if (__lhs.index() < __rhs.index()) return false;
-  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs);
-}
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator<=(const variant<_Types...>& __lhs,
-                          const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__lhs.valueless_by_exception()) return true;
-  if (__rhs.valueless_by_exception()) return false;
-  if (__lhs.index() < __rhs.index()) return true;
-  if (__lhs.index() > __rhs.index()) return false;
-  return __variant::__visit_value_at(
-      __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs);
-}
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator>=(const variant<_Types...>& __lhs,
-                          const variant<_Types...>& __rhs) {
-  using __variant_detail::__visitation::__variant;
-  if (__rhs.valueless_by_exception()) return true;
-  if (__lhs.valueless_by_exception()) return false;
-  if (__lhs.index() > __rhs.index()) return true;
-  if (__lhs.index() < __rhs.index()) return false;
-  return __variant::__visit_value_at(
-      __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs);
-}
-
-template <class _Visitor, class... _Vs>
-inline _LIBCPP_INLINE_VISIBILITY
-_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
-constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
-  using __variant_detail::__visitation::__variant;
-  bool __results[] = {__vs.valueless_by_exception()...};
-  for (bool __result : __results) {
-    if (__result) {
-      __throw_bad_variant_access();
-    }
-  }
-  return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
-                                  _VSTD::forward<_Vs>(__vs)...);
-}
-
-struct _LIBCPP_TEMPLATE_VIS monostate {};
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator<(monostate, monostate) noexcept { return false; }
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator>(monostate, monostate) noexcept { return false; }
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator<=(monostate, monostate) noexcept { return true; }
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator>=(monostate, monostate) noexcept { return true; }
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator==(monostate, monostate) noexcept { return true; }
-
-inline _LIBCPP_INLINE_VISIBILITY
-constexpr bool operator!=(monostate, monostate) noexcept { return false; }
-
-template <class... _Types>
-inline _LIBCPP_INLINE_VISIBILITY
-auto swap(variant<_Types...>& __lhs,
-          variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs)))
-    -> decltype(__lhs.swap(__rhs)) {
-  __lhs.swap(__rhs);
-}
-
-template <class... _Types>
-struct _LIBCPP_TEMPLATE_VIS hash<
-    __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> {
-  using argument_type = variant<_Types...>;
-  using result_type = size_t;
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  result_type operator()(const argument_type& __v) const {
-    using __variant_detail::__visitation::__variant;
-    size_t __res =
-        __v.valueless_by_exception()
-               ? 299792458 // Random value chosen by the universe upon creation
-               : __variant::__visit_alt(
-                     [](const auto& __alt) {
-                       using __alt_type = __uncvref_t<decltype(__alt)>;
-                       using __value_type = remove_const_t<
-                         typename __alt_type::__value_type>;
-                       return hash<__value_type>{}(__alt.__value);
-                     },
-                     __v);
-    return __hash_combine(__res, hash<size_t>{}(__v.index()));
-  }
-};
-
-template <>
-struct _LIBCPP_TEMPLATE_VIS hash<monostate> {
-  using argument_type = monostate;
-  using result_type = size_t;
-
-  inline _LIBCPP_INLINE_VISIBILITY
-  result_type operator()(const argument_type&) const _NOEXCEPT {
-    return 66740831; // return a fundamentally attractive random value.
-  }
-};
-
-#endif  // _LIBCPP_STD_VER > 14
-
-_LIBCPP_END_NAMESPACE_STD
-
-_LIBCPP_POP_MACROS
-
-#endif  // _LIBCPP_VARIANT