intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 1625 insertions, 0 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/include/tuple b/contrib/libs/cxxsupp/libcxx/include/tuple
new file mode 100644
index 0000000000..be57f984dd
--- /dev/null
+++ b/contrib/libs/cxxsupp/libcxx/include/tuple
@@ -0,0 +1,1625 @@
+// -*- C++ -*-
+//===--------------------------- tuple ------------------------------------===//
+//
+// 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_TUPLE
+#define _LIBCPP_TUPLE
+
+/*
+    tuple synopsis
+
+namespace std
+{
+
+template <class... T>
+class tuple {
+public:
+    explicit(see-below) constexpr tuple();
+    explicit(see-below) tuple(const T&...);  // constexpr in C++14
+    template <class... U>
+        explicit(see-below) tuple(U&&...);  // constexpr in C++14
+    tuple(const tuple&) = default;
+    tuple(tuple&&) = default;
+    template <class... U>
+        explicit(see-below) tuple(const tuple<U...>&);  // constexpr in C++14
+    template <class... U>
+        explicit(see-below) tuple(tuple<U...>&&);  // constexpr in C++14
+    template <class U1, class U2>
+        explicit(see-below) tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14
+    template <class U1, class U2>
+        explicit(see-below) tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14
+
+    // allocator-extended constructors
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a);
+    template <class Alloc>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const T&...);          // constexpr in C++20
+    template <class Alloc, class... U>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, U&&...);               // constexpr in C++20
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a, const tuple&);                             // constexpr in C++20
+    template <class Alloc>
+        tuple(allocator_arg_t, const Alloc& a, tuple&&);                                  // constexpr in C++20
+    template <class Alloc, class... U>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);   // constexpr in C++20
+    template <class Alloc, class... U>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);        // constexpr in C++20
+    template <class Alloc, class U1, class U2>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);  // constexpr in C++20
+    template <class Alloc, class U1, class U2>
+        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);       // constexpr in C++20
+
+    tuple& operator=(const tuple&);                                                       // constexpr in C++20
+    tuple& operator=(tuple&&) noexcept(is_nothrow_move_assignable_v<T> && ...);           // constexpr in C++20
+    template <class... U>
+        tuple& operator=(const tuple<U...>&);                                             // constexpr in C++20
+    template <class... U>
+        tuple& operator=(tuple<U...>&&);                                                  // constexpr in C++20
+    template <class U1, class U2>
+        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2                   // constexpr in C++20
+    template <class U1, class U2>
+        tuple& operator=(pair<U1, U2>&&); // iff sizeof...(T) == 2                        // constexpr in C++20
+
+    template<class U, size_t N>
+        tuple& operator=(array<U, N> const&) // iff sizeof...(T) == N, EXTENSION
+    template<class U, size_t N>
+        tuple& operator=(array<U, N>&&) // iff sizeof...(T) == N, EXTENSION
+
+    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));               // constexpr in C++20
+};
+
+template <class ...T>
+tuple(T...) -> tuple<T...>;                                         // since C++17
+template <class T1, class T2>
+tuple(pair<T1, T2>) -> tuple<T1, T2>;                               // since C++17
+template <class Alloc, class ...T>
+tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>;                 // since C++17
+template <class Alloc, class T1, class T2>
+tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;       // since C++17
+template <class Alloc, class ...T>
+tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>;          // since C++17
+
+inline constexpr unspecified ignore;
+
+template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
+template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
+template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14
+template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
+
+// [tuple.apply], calling a function with a tuple of arguments:
+template <class F, class Tuple>
+  constexpr decltype(auto) apply(F&& f, Tuple&& t); // C++17
+template <class T, class Tuple>
+  constexpr T make_from_tuple(Tuple&& t); // C++17
+
+// 20.4.1.4, tuple helper classes:
+template <class T> struct tuple_size; // undefined
+template <class... T> struct tuple_size<tuple<T...>>;
+template <class T>
+ inline constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17
+template <size_t I, class T> struct tuple_element; // undefined
+template <size_t I, class... T> struct tuple_element<I, tuple<T...>>;
+template <size_t I, class T>
+  using tuple_element_t = typename tuple_element <I, T>::type; // C++14
+
+// 20.4.1.5, element access:
+template <size_t I, class... T>
+    typename tuple_element<I, tuple<T...>>::type&
+    get(tuple<T...>&) noexcept; // constexpr in C++14
+template <size_t I, class... T>
+    const typename tuple_element<I, tuple<T...>>::type&
+    get(const tuple<T...>&) noexcept; // constexpr in C++14
+template <size_t I, class... T>
+    typename tuple_element<I, tuple<T...>>::type&&
+    get(tuple<T...>&&) noexcept; // constexpr in C++14
+template <size_t I, class... T>
+    const typename tuple_element<I, tuple<T...>>::type&&
+    get(const tuple<T...>&&) noexcept; // constexpr in C++14
+
+template <class T1, class... T>
+    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
+template <class T1, class... T>
+    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14
+template <class T1, class... T>
+    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
+template <class T1, class... T>
+    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14
+
+// 20.4.1.6, relational operators:
+template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
+template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
+template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
+template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
+template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
+template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
+template<class... T, class... U>
+  constexpr common_comparison_category_t<synth-three-way-result<T, U>...>
+    operator<=>(const tuple<T...>&, const tuple<U...>&);                                  // since C++20
+
+template <class... Types, class Alloc>
+  struct uses_allocator<tuple<Types...>, Alloc>;
+
+template <class... Types>
+  void
+  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
+
+}  // std
+
+*/
+
+#include <__compare/common_comparison_category.h>
+#include <__compare/synth_three_way.h>
+#include <__config>
+#include <__functional/unwrap_ref.h>
+#include <__functional_base>
+#include <__memory/allocator_arg_t.h>
+#include <__memory/uses_allocator.h>
+#include <__tuple>
+#include <__utility/forward.h>
+#include <__utility/integer_sequence.h>
+#include <__utility/move.h>
+#include <compare>
+#include <cstddef>
+#include <type_traits>
+#include <utility>
+#include <version>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_CXX03_LANG
+
+
+// __tuple_leaf
+
+template <size_t _Ip, class _Hp,
+          bool=is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value
+         >
+class __tuple_leaf;
+
+template <size_t _Ip, class _Hp, bool _Ep>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
+    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
+{
+    swap(__x.get(), __y.get());
+}
+
+template <size_t _Ip, class _Hp, bool>
+class __tuple_leaf
+{
+    _Hp __value_;
+
+    template <class _Tp>
+    static constexpr bool __can_bind_reference() {
+#if __has_keyword(__reference_binds_to_temporary) && !defined(__CUDACC__)
+      return !__reference_binds_to_temporary(_Hp, _Tp);
+#else
+      return true;
+#endif
+    }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11
+    __tuple_leaf& operator=(const __tuple_leaf&);
+public:
+    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
+             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : __value_()
+       {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
+            : __value_()
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
+            : __value_(allocator_arg_t(), __a)
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
+            : __value_(__a)
+        {static_assert(!is_reference<_Hp>::value,
+              "Attempted to default construct a reference element in a tuple");}
+
+    template <class _Tp,
+              class = __enable_if_t<
+                  _And<
+                      _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
+                      is_constructible<_Hp, _Tp>
+                    >::value
+                >
+            >
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
+            : __value_(_VSTD::forward<_Tp>(__t))
+        {static_assert(__can_bind_reference<_Tp&&>(),
+       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
+            : __value_(_VSTD::forward<_Tp>(__t))
+        {static_assert(__can_bind_reference<_Tp&&>(),
+       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
+            : __value_(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
+        {static_assert(!is_reference<_Hp>::value,
+            "Attempted to uses-allocator construct a reference element in a tuple");}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
+            : __value_(_VSTD::forward<_Tp>(__t), __a)
+        {static_assert(!is_reference<_Hp>::value,
+           "Attempted to uses-allocator construct a reference element in a tuple");}
+
+    __tuple_leaf(const __tuple_leaf& __t) = default;
+    __tuple_leaf(__tuple_leaf&& __t) = default;
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
+    {
+        _VSTD::swap(*this, __t);
+        return 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return __value_;}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return __value_;}
+};
+
+template <size_t _Ip, class _Hp>
+class __tuple_leaf<_Ip, _Hp, true>
+    : private _Hp
+{
+    _LIBCPP_CONSTEXPR_AFTER_CXX11
+    __tuple_leaf& operator=(const __tuple_leaf&);
+public:
+    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
+             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
+            : _Hp(allocator_arg_t(), __a) {}
+
+    template <class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
+            : _Hp(__a) {}
+
+    template <class _Tp,
+              class = __enable_if_t<
+                  _And<
+                    _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
+                    is_constructible<_Hp, _Tp>
+                  >::value
+                >
+            >
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
+            : _Hp(_VSTD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
+            : _Hp(_VSTD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
+            : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
+
+    template <class _Tp, class _Alloc>
+        _LIBCPP_INLINE_VISIBILITY constexpr
+        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
+            : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
+
+    __tuple_leaf(__tuple_leaf const &) = default;
+    __tuple_leaf(__tuple_leaf &&) = default;
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    int
+    swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
+    {
+        _VSTD::swap(*this, __t);
+        return 0;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
+};
+
+template <class ..._Tp>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+void __swallow(_Tp&&...) _NOEXCEPT {}
+
+template <class _Tp>
+struct __all_default_constructible;
+
+template <class ..._Tp>
+struct __all_default_constructible<__tuple_types<_Tp...>>
+    : __all<is_default_constructible<_Tp>::value...>
+{ };
+
+// __tuple_impl
+
+template<class _Indx, class ..._Tp> struct __tuple_impl;
+
+template<size_t ..._Indx, class ..._Tp>
+struct _LIBCPP_DECLSPEC_EMPTY_BASES __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
+    : public __tuple_leaf<_Indx, _Tp>...
+{
+    _LIBCPP_INLINE_VISIBILITY
+    constexpr __tuple_impl()
+        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
+
+    template <size_t ..._Uf, class ..._Tf,
+              size_t ..._Ul, class ..._Tl, class ..._Up>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit
+        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
+                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
+                     _Up&&... __u)
+                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
+                                 __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
+            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
+            __tuple_leaf<_Ul, _Tl>()...
+            {}
+
+#if defined(__NVCC__) && defined(_LIBCPP_COMPILER_MSVC)
+    // Yandex-specific: specialize the preceding constructor for the
+    // case of empty _Ul and _Tl to work around nvcc+msvc bug
+    // compiling libcxx std::map<int, int> m; m[1] = 2.
+    template <size_t ..._Uf, class ..._Tf,
+              class ..._Up>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit
+        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
+                     __tuple_indices<>, __tuple_types<>,
+                     _Up&&... __u)
+                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value)) :
+            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...
+            {}
+    // End of Yandex-specific
+#endif
+
+    template <class _Alloc, size_t ..._Uf, class ..._Tf,
+              size_t ..._Ul, class ..._Tl, class ..._Up>
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        explicit
+        __tuple_impl(allocator_arg_t, const _Alloc& __a,
+                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
+                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
+                     _Up&&... __u) :
+            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
+            _VSTD::forward<_Up>(__u))...,
+            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
+            {}
+
+    template <class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_constructible<_Tuple, tuple<_Tp...> >::value
+                      >::type
+             >
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
+            : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
+            {}
+
+    template <class _Alloc, class _Tuple,
+              class = typename enable_if
+                      <
+                         __tuple_constructible<_Tuple, tuple<_Tp...> >::value
+                      >::type
+             >
+        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
+            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a,
+                                       _VSTD::forward<typename tuple_element<_Indx,
+                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
+            {}
+
+    __tuple_impl(const __tuple_impl&) = default;
+    __tuple_impl(__tuple_impl&&) = default;
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    void swap(__tuple_impl& __t)
+        _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
+    {
+        _VSTD::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
+    }
+};
+
+template<class _Dest, class _Source, size_t ..._Np>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+void __memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {
+    _VSTD::__swallow(((_VSTD::get<_Np>(__dest) = _VSTD::get<_Np>(__source)), void(), 0)...);
+    }
+
+template<class _Dest, class _Source, class ..._Up, size_t ..._Np>
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+void __memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {
+    _VSTD::__swallow(((
+        _VSTD::get<_Np>(__dest) = _VSTD::forward<_Up>(_VSTD::get<_Np>(__source))
+    ), void(), 0)...);
+    }
+
+template <class ..._Tp>
+class _LIBCPP_TEMPLATE_VIS tuple
+{
+    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;
+
+    _BaseT __base_;
+
+    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
+        typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
+    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
+        const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
+    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
+        typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
+    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_AFTER_CXX11
+        const typename tuple_element<_Jp, tuple<_Up...> >::type&& get(const tuple<_Up...>&&) _NOEXCEPT;
+public:
+    // [tuple.cnstr]
+
+    // tuple() constructors (including allocator_arg_t variants)
+    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
+        _And<
+            _IsImpDefault<_Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    tuple()
+        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
+    { }
+
+    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
+              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
+        _And<
+            _IsDefault<_Tp>...,
+            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+    explicit tuple()
+        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
+    { }
+
+    template <class _Alloc, template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
+        _And<
+            _IsImpDefault<_Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, _Alloc const& __a)
+      : __base_(allocator_arg_t(), __a,
+                    __tuple_indices<>(), __tuple_types<>(),
+                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
+                    __tuple_types<_Tp...>()) {}
+
+    template <class _Alloc,
+              template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
+              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
+        _And<
+            _IsDefault<_Tp>...,
+            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, _Alloc const& __a)
+      : __base_(allocator_arg_t(), __a,
+                    __tuple_indices<>(), __tuple_types<>(),
+                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
+                    __tuple_types<_Tp...>()) {}
+
+    // tuple(const T&...) constructors (including allocator_arg_t variants)
+    template <template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) >= 1>,
+            is_copy_constructible<_Tp>...,
+            is_convertible<const _Tp&, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(const _Tp& ... __t)
+        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
+        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    template <template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) >= 1>,
+            is_copy_constructible<_Tp>...,
+            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(const _Tp& ... __t)
+        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
+        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) >= 1>,
+            is_copy_constructible<_Tp>...,
+            is_convertible<const _Tp&, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
+        : __base_(allocator_arg_t(), __a,
+                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) >= 1>,
+            is_copy_constructible<_Tp>...,
+            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
+        : __base_(allocator_arg_t(), __a,
+                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
+                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
+                typename __make_tuple_indices<0>::type(),
+                typename __make_tuple_types<tuple, 0>::type(),
+                __t...
+               ) {}
+
+    // tuple(U&& ...) constructors (including allocator_arg_t variants)
+    template <class ..._Up> struct _IsThisTuple : false_type { };
+    template <class _Up> struct _IsThisTuple<_Up> : is_same<__uncvref_t<_Up>, tuple> { };
+
+    template <class ..._Up>
+    struct _EnableUTypesCtor : _And<
+        _BoolConstant<sizeof...(_Tp) >= 1>,
+        _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
+        is_constructible<_Tp, _Up>...
+    > { };
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableUTypesCtor<_Up...>,
+            is_convertible<_Up, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(_Up&&... __u)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
+        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _VSTD::forward<_Up>(__u)...) {}
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableUTypesCtor<_Up...>,
+            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(_Up&&... __u)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
+        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _VSTD::forward<_Up>(__u)...) {}
+
+    template <class _Alloc, class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableUTypesCtor<_Up...>,
+            is_convertible<_Up, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
+        : __base_(allocator_arg_t(), __a,
+                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _VSTD::forward<_Up>(__u)...) {}
+
+    template <class _Alloc, class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableUTypesCtor<_Up...>,
+            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
+        : __base_(allocator_arg_t(), __a,
+                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
+                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
+                    _VSTD::forward<_Up>(__u)...) {}
+
+    // Copy and move constructors (including the allocator_arg_t variants)
+    tuple(const tuple&) = default;
+    tuple(tuple&&) = default;
+
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
+        _And<is_copy_constructible<_Tp>...>::value
+    , int> = 0>
+    tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)
+        : __base_(allocator_arg_t(), __alloc, __t)
+    { }
+
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
+        _And<is_move_constructible<_Tp>...>::value
+    , int> = 0>
+    tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)
+        : __base_(allocator_arg_t(), __alloc, _VSTD::move(__t))
+    { }
+
+    // tuple(const tuple<U...>&) constructors (including allocator_arg_t variants)
+    template <class ..._Up>
+    struct _EnableCopyFromOtherTuple : _And<
+        _Not<is_same<tuple<_Tp...>, tuple<_Up...> > >,
+        _Lazy<_Or,
+            _BoolConstant<sizeof...(_Tp) != 1>,
+            // _Tp and _Up are 1-element packs - the pack expansions look
+            // weird to avoid tripping up the type traits in degenerate cases
+            _Lazy<_And,
+                _Not<is_convertible<const tuple<_Up>&, _Tp> >...,
+                _Not<is_constructible<_Tp, const tuple<_Up>&> >...
+            >
+        >,
+        is_constructible<_Tp, const _Up&>...
+    > { };
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableCopyFromOtherTuple<_Up...>,
+            is_convertible<const _Up&, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(const tuple<_Up...>& __t)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
+        : __base_(__t)
+    { }
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableCopyFromOtherTuple<_Up...>,
+            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(const tuple<_Up...>& __t)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
+        : __base_(__t)
+    { }
+
+    template <class ..._Up, class _Alloc, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableCopyFromOtherTuple<_Up...>,
+            is_convertible<const _Up&, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
+        : __base_(allocator_arg_t(), __a, __t)
+    { }
+
+    template <class ..._Up, class _Alloc, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableCopyFromOtherTuple<_Up...>,
+            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
+        : __base_(allocator_arg_t(), __a, __t)
+    { }
+
+    // tuple(tuple<U...>&&) constructors (including allocator_arg_t variants)
+    template <class ..._Up>
+    struct _EnableMoveFromOtherTuple : _And<
+        _Not<is_same<tuple<_Tp...>, tuple<_Up...> > >,
+        _Lazy<_Or,
+            _BoolConstant<sizeof...(_Tp) != 1>,
+            // _Tp and _Up are 1-element packs - the pack expansions look
+            // weird to avoid tripping up the type traits in degenerate cases
+            _Lazy<_And,
+                _Not<is_convertible<tuple<_Up>, _Tp> >...,
+                _Not<is_constructible<_Tp, tuple<_Up> > >...
+            >
+        >,
+        is_constructible<_Tp, _Up>...
+    > { };
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableMoveFromOtherTuple<_Up...>,
+            is_convertible<_Up, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(tuple<_Up...>&& __t)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
+        : __base_(_VSTD::move(__t))
+    { }
+
+    template <class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableMoveFromOtherTuple<_Up...>,
+            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(tuple<_Up...>&& __t)
+        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
+        : __base_(_VSTD::move(__t))
+    { }
+
+    template <class _Alloc, class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableMoveFromOtherTuple<_Up...>,
+            is_convertible<_Up, _Tp>... // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
+        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
+    { }
+
+    template <class _Alloc, class ..._Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
+            _EnableMoveFromOtherTuple<_Up...>,
+            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
+        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
+    { }
+
+    // tuple(const pair<U1, U2>&) constructors (including allocator_arg_t variants)
+    template <class _Up1, class _Up2, class ..._DependentTp>
+    struct _EnableImplicitCopyFromPair : _And<
+        is_constructible<_FirstType<_DependentTp...>, const _Up1&>,
+        is_constructible<_SecondType<_DependentTp...>, const _Up2&>,
+        is_convertible<const _Up1&, _FirstType<_DependentTp...> >, // explicit check
+        is_convertible<const _Up2&, _SecondType<_DependentTp...> >
+    > { };
+
+    template <class _Up1, class _Up2, class ..._DependentTp>
+    struct _EnableExplicitCopyFromPair : _And<
+        is_constructible<_FirstType<_DependentTp...>, const _Up1&>,
+        is_constructible<_SecondType<_DependentTp...>, const _Up2&>,
+        _Not<is_convertible<const _Up1&, _FirstType<_DependentTp...> > >, // explicit check
+        _Not<is_convertible<const _Up2&, _SecondType<_DependentTp...> > >
+    > { };
+
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableImplicitCopyFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(const pair<_Up1, _Up2>& __p)
+        _NOEXCEPT_((_And<
+            is_nothrow_constructible<_FirstType<_Tp...>, const _Up1&>,
+            is_nothrow_constructible<_SecondType<_Tp...>, const _Up2&>
+        >::value))
+        : __base_(__p)
+    { }
+
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableExplicitCopyFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(const pair<_Up1, _Up2>& __p)
+        _NOEXCEPT_((_And<
+            is_nothrow_constructible<_FirstType<_Tp...>, const _Up1&>,
+            is_nothrow_constructible<_SecondType<_Tp...>, const _Up2&>
+        >::value))
+        : __base_(__p)
+    { }
+
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableImplicitCopyFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
+        : __base_(allocator_arg_t(), __a, __p)
+    { }
+
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableExplicitCopyFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
+        : __base_(allocator_arg_t(), __a, __p)
+    { }
+
+    // tuple(pair<U1, U2>&&) constructors (including allocator_arg_t variants)
+    template <class _Up1, class _Up2, class ..._DependentTp>
+    struct _EnableImplicitMoveFromPair : _And<
+        is_constructible<_FirstType<_DependentTp...>, _Up1>,
+        is_constructible<_SecondType<_DependentTp...>, _Up2>,
+        is_convertible<_Up1, _FirstType<_DependentTp...> >, // explicit check
+        is_convertible<_Up2, _SecondType<_DependentTp...> >
+    > { };
+
+    template <class _Up1, class _Up2, class ..._DependentTp>
+    struct _EnableExplicitMoveFromPair : _And<
+        is_constructible<_FirstType<_DependentTp...>, _Up1>,
+        is_constructible<_SecondType<_DependentTp...>, _Up2>,
+        _Not<is_convertible<_Up1, _FirstType<_DependentTp...> > >, // explicit check
+        _Not<is_convertible<_Up2, _SecondType<_DependentTp...> > >
+    > { };
+
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableImplicitMoveFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    tuple(pair<_Up1, _Up2>&& __p)
+        _NOEXCEPT_((_And<
+            is_nothrow_constructible<_FirstType<_Tp...>, _Up1>,
+            is_nothrow_constructible<_SecondType<_Tp...>, _Up2>
+        >::value))
+        : __base_(_VSTD::move(__p))
+    { }
+
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableExplicitMoveFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    explicit tuple(pair<_Up1, _Up2>&& __p)
+        _NOEXCEPT_((_And<
+            is_nothrow_constructible<_FirstType<_Tp...>, _Up1>,
+            is_nothrow_constructible<_SecondType<_Tp...>, _Up2>
+        >::value))
+        : __base_(_VSTD::move(__p))
+    { }
+
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableImplicitMoveFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
+        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
+    { }
+
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            _EnableExplicitMoveFromPair<_Up1, _Up2, _Tp...>
+        >::value
+    , int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    explicit tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
+        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
+    { }
+
+    // [tuple.assign]
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple)
+        _NOEXCEPT_((_And<is_nothrow_copy_assignable<_Tp>...>::value))
+    {
+        _VSTD::__memberwise_copy_assign(*this, __tuple,
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple)
+        _NOEXCEPT_((_And<is_nothrow_move_assignable<_Tp>...>::value))
+    {
+        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
+            __tuple_types<_Tp...>(),
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    template<class... _Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
+            is_assignable<_Tp&, _Up const&>...
+        >::value
+    ,int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(tuple<_Up...> const& __tuple)
+        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
+    {
+        _VSTD::__memberwise_copy_assign(*this, __tuple,
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    template<class... _Up, __enable_if_t<
+        _And<
+            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
+            is_assignable<_Tp&, _Up>...
+        >::value
+    ,int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(tuple<_Up...>&& __tuple)
+        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
+    {
+        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
+            __tuple_types<_Up...>(),
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    template<class _Up1, class _Up2, class _Dep = true_type, __enable_if_t<
+        _And<_Dep,
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            is_assignable<_FirstType<_Tp..., _Dep>&, _Up1 const&>,
+            is_assignable<_SecondType<_Tp..., _Dep>&, _Up2 const&>
+        >::value
+    ,int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(pair<_Up1, _Up2> const& __pair)
+        _NOEXCEPT_((_And<
+            is_nothrow_assignable<_FirstType<_Tp...>&, _Up1 const&>,
+            is_nothrow_assignable<_SecondType<_Tp...>&, _Up2 const&>
+        >::value))
+    {
+        _VSTD::get<0>(*this) = __pair.first;
+        _VSTD::get<1>(*this) = __pair.second;
+        return *this;
+    }
+
+    template<class _Up1, class _Up2, class _Dep = true_type, __enable_if_t<
+        _And<_Dep,
+            _BoolConstant<sizeof...(_Tp) == 2>,
+            is_assignable<_FirstType<_Tp..., _Dep>&, _Up1>,
+            is_assignable<_SecondType<_Tp..., _Dep>&, _Up2>
+        >::value
+    ,int> = 0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(pair<_Up1, _Up2>&& __pair)
+        _NOEXCEPT_((_And<
+            is_nothrow_assignable<_FirstType<_Tp...>&, _Up1>,
+            is_nothrow_assignable<_SecondType<_Tp...>&, _Up2>
+        >::value))
+    {
+        _VSTD::get<0>(*this) = _VSTD::forward<_Up1>(__pair.first);
+        _VSTD::get<1>(*this) = _VSTD::forward<_Up2>(__pair.second);
+        return *this;
+    }
+
+    // EXTENSION
+    template<class _Up, size_t _Np, class = __enable_if_t<
+        _And<
+            _BoolConstant<_Np == sizeof...(_Tp)>,
+            is_assignable<_Tp&, _Up const&>...
+        >::value
+    > >
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(array<_Up, _Np> const& __array)
+        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
+    {
+        _VSTD::__memberwise_copy_assign(*this, __array,
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    // EXTENSION
+    template<class _Up, size_t _Np, class = void, class = __enable_if_t<
+        _And<
+            _BoolConstant<_Np == sizeof...(_Tp)>,
+            is_assignable<_Tp&, _Up>...
+        >::value
+    > >
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    tuple& operator=(array<_Up, _Np>&& __array)
+        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
+    {
+        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__array),
+            __tuple_types<_If<true, _Up, _Tp>...>(),
+            typename __make_tuple_indices<sizeof...(_Tp)>::type());
+        return *this;
+    }
+
+    // [tuple.swap]
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
+        {__base_.swap(__t.__base_);}
+};
+
+template <>
+class _LIBCPP_TEMPLATE_VIS tuple<>
+{
+public:
+    _LIBCPP_INLINE_VISIBILITY constexpr
+        tuple() _NOEXCEPT = default;
+    template <class _Alloc>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
+    template <class _Alloc>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
+    template <class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        tuple(array<_Up, 0>) _NOEXCEPT {}
+    template <class _Alloc, class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+        tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+    void swap(tuple&) _NOEXCEPT {}
+};
+
+#if _LIBCPP_STD_VER >= 17
+template <class ..._Tp>
+tuple(_Tp...) -> tuple<_Tp...>;
+template <class _Tp1, class _Tp2>
+tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
+template <class _Alloc, class ..._Tp>
+tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;
+template <class _Alloc, class _Tp1, class _Tp2>
+tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
+template <class _Alloc, class ..._Tp>
+tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;
+#endif
+
+template <class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+typename enable_if
+<
+    __all<__is_swappable<_Tp>::value...>::value,
+    void
+>::type
+swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
+                 _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
+    {__t.swap(__u);}
+
+// get
+
+template <size_t _Ip, class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+typename tuple_element<_Ip, tuple<_Tp...> >::type&
+get(tuple<_Tp...>& __t) _NOEXCEPT
+{
+    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
+    return static_cast<__tuple_leaf<_Ip, type>&>(__t.__base_).get();
+}
+
+template <size_t _Ip, class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const typename tuple_element<_Ip, tuple<_Tp...> >::type&
+get(const tuple<_Tp...>& __t) _NOEXCEPT
+{
+    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
+    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.__base_).get();
+}
+
+template <size_t _Ip, class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+typename tuple_element<_Ip, tuple<_Tp...> >::type&&
+get(tuple<_Tp...>&& __t) _NOEXCEPT
+{
+    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
+    return static_cast<type&&>(
+             static_cast<__tuple_leaf<_Ip, type>&&>(__t.__base_).get());
+}
+
+template <size_t _Ip, class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
+get(const tuple<_Tp...>&& __t) _NOEXCEPT
+{
+    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
+    return static_cast<const type&&>(
+             static_cast<const __tuple_leaf<_Ip, type>&&>(__t.__base_).get());
+}
+
+#if _LIBCPP_STD_VER > 11
+
+namespace __find_detail {
+
+static constexpr size_t __not_found = static_cast<size_t>(-1);
+static constexpr size_t __ambiguous = __not_found - 1;
+
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) {
+    return !__matches ? __res :
+        (__res == __not_found ? __curr_i : __ambiguous);
+}
+
+template <size_t _Nx>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {
+  return __i == _Nx ? __not_found :
+      __find_idx_return(__i, __find_idx(__i + 1, __matches), __matches[__i]);
+}
+
+template <class _T1, class ..._Args>
+struct __find_exactly_one_checked {
+    static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...};
+    static constexpr size_t value = __find_detail::__find_idx(0, __matches);
+    static_assert(value != __not_found, "type not found in type list" );
+    static_assert(value != __ambiguous, "type occurs more than once in type list");
+};
+
+template <class _T1>
+struct __find_exactly_one_checked<_T1> {
+    static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");
+};
+
+} // namespace __find_detail;
+
+template <typename _T1, typename... _Args>
+struct __find_exactly_one_t
+    : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {
+};
+
+template <class _T1, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1& get(tuple<_Args...>& __tup) noexcept
+{
+    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
+}
+
+template <class _T1, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
+{
+    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
+}
+
+template <class _T1, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
+{
+    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
+}
+
+template <class _T1, class... _Args>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _T1 const&& get(tuple<_Args...> const&& __tup) noexcept
+{
+    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
+}
+
+#endif
+
+// tie
+
+template <class ..._Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+tuple<_Tp&...>
+tie(_Tp&... __t) _NOEXCEPT
+{
+    return tuple<_Tp&...>(__t...);
+}
+
+template <class _Up>
+struct __ignore_t
+{
+    template <class _Tp>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    const __ignore_t& operator=(_Tp&&) const {return *this;}
+};
+
+namespace {
+  constexpr __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>();
+}
+
+template <class... _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+tuple<typename __unwrap_ref_decay<_Tp>::type...>
+make_tuple(_Tp&&... __t)
+{
+    return tuple<typename __unwrap_ref_decay<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
+}
+
+template <class... _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+tuple<_Tp&&...>
+forward_as_tuple(_Tp&&... __t) _NOEXCEPT
+{
+    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
+}
+
+template <size_t _Ip>
+struct __tuple_equal
+{
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _Tp& __x, const _Up& __y)
+    {
+        return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
+    }
+};
+
+template <>
+struct __tuple_equal<0>
+{
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _Tp&, const _Up&)
+    {
+        return true;
+    }
+};
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
+    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
+}
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)
+
+// operator<=>
+
+template <class ..._Tp, class ..._Up, size_t ..._Is>
+_LIBCPP_HIDE_FROM_ABI constexpr
+auto
+__tuple_compare_three_way(const tuple<_Tp...>& __x, const tuple<_Up...>& __y, index_sequence<_Is...>) {
+    common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...> __result = strong_ordering::equal;
+    static_cast<void>(((__result = _VSTD::__synth_three_way(_VSTD::get<_Is>(__x), _VSTD::get<_Is>(__y)), __result != 0) || ...));
+    return __result;
+}
+
+template <class ..._Tp, class ..._Up>
+requires (sizeof...(_Tp) == sizeof...(_Up))
+_LIBCPP_HIDE_FROM_ABI constexpr
+common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...>
+operator<=>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return _VSTD::__tuple_compare_three_way(__x, __y, index_sequence_for<_Tp...>{});
+}
+
+#else // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__x == __y);
+}
+
+template <size_t _Ip>
+struct __tuple_less
+{
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _Tp& __x, const _Up& __y)
+    {
+        const size_t __idx = tuple_size<_Tp>::value - _Ip;
+        if (_VSTD::get<__idx>(__x) < _VSTD::get<__idx>(__y))
+            return true;
+        if (_VSTD::get<__idx>(__y) < _VSTD::get<__idx>(__x))
+            return false;
+        return __tuple_less<_Ip-1>()(__x, __y);
+    }
+};
+
+template <>
+struct __tuple_less<0>
+{
+    template <class _Tp, class _Up>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    bool operator()(const _Tp&, const _Up&)
+    {
+        return false;
+    }
+};
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
+    return __tuple_less<sizeof...(_Tp)>()(__x, __y);
+}
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return __y < __x;
+}
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__x < __y);
+}
+
+template <class ..._Tp, class ..._Up>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+bool
+operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
+{
+    return !(__y < __x);
+}
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)
+
+// tuple_cat
+
+template <class _Tp, class _Up> struct __tuple_cat_type;
+
+template <class ..._Ttypes, class ..._Utypes>
+struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
+{
+    typedef _LIBCPP_NODEBUG tuple<_Ttypes..., _Utypes...> type;
+};
+
+template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
+struct __tuple_cat_return_1
+{
+};
+
+template <class ..._Types, class _Tuple0>
+struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
+{
+    typedef _LIBCPP_NODEBUG typename __tuple_cat_type<tuple<_Types...>,
+            typename __make_tuple_types<typename __uncvref<_Tuple0>::type>::type>::type
+                                                                           type;
+};
+
+template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
+struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
+    : public __tuple_cat_return_1<
+                 typename __tuple_cat_type<
+                     tuple<_Types...>,
+                     typename __make_tuple_types<typename __uncvref<_Tuple0>::type>::type
+                 >::type,
+                 __tuple_like<typename remove_reference<_Tuple1>::type>::value,
+                 _Tuple1, _Tuples...>
+{
+};
+
+template <class ..._Tuples> struct __tuple_cat_return;
+
+template <class _Tuple0, class ..._Tuples>
+struct __tuple_cat_return<_Tuple0, _Tuples...>
+    : public __tuple_cat_return_1<tuple<>,
+         __tuple_like<typename remove_reference<_Tuple0>::type>::value, _Tuple0,
+                                                                     _Tuples...>
+{
+};
+
+template <>
+struct __tuple_cat_return<>
+{
+    typedef _LIBCPP_NODEBUG tuple<> type;
+};
+
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+tuple<>
+tuple_cat()
+{
+    return tuple<>();
+}
+
+template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
+struct __tuple_cat_return_ref_imp;
+
+template <class ..._Types, size_t ..._I0, class _Tuple0>
+struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
+{
+    typedef _LIBCPP_NODEBUG typename remove_reference<_Tuple0>::type _T0;
+    typedef tuple<_Types..., typename __apply_cv<_Tuple0,
+                          typename tuple_element<_I0, _T0>::type>::type&&...> type;
+};
+
+template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
+struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
+                                  _Tuple0, _Tuple1, _Tuples...>
+    : public __tuple_cat_return_ref_imp<
+         tuple<_Types..., typename __apply_cv<_Tuple0,
+               typename tuple_element<_I0,
+                  typename remove_reference<_Tuple0>::type>::type>::type&&...>,
+         typename __make_tuple_indices<tuple_size<typename
+                                 remove_reference<_Tuple1>::type>::value>::type,
+         _Tuple1, _Tuples...>
+{
+};
+
+template <class _Tuple0, class ..._Tuples>
+struct __tuple_cat_return_ref
+    : public __tuple_cat_return_ref_imp<tuple<>,
+               typename __make_tuple_indices<
+                        tuple_size<typename remove_reference<_Tuple0>::type>::value
+               >::type, _Tuple0, _Tuples...>
+{
+};
+
+template <class _Types, class _I0, class _J0>
+struct __tuple_cat;
+
+template <class ..._Types, size_t ..._I0, size_t ..._J0>
+struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
+{
+    template <class _Tuple0>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
+    operator()(tuple<_Types...> __t, _Tuple0&& __t0)
+    {
+        return _VSTD::forward_as_tuple(
+            _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
+            _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
+    }
+
+    template <class _Tuple0, class _Tuple1, class ..._Tuples>
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
+    operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
+    {
+        typedef _LIBCPP_NODEBUG typename remove_reference<_Tuple0>::type _T0;
+        typedef _LIBCPP_NODEBUG typename remove_reference<_Tuple1>::type _T1;
+        return __tuple_cat<
+            tuple<_Types...,
+                  typename __apply_cv<_Tuple0, typename tuple_element<
+                                                   _J0, _T0>::type>::type&&...>,
+            typename __make_tuple_indices<sizeof...(_Types) +
+                                          tuple_size<_T0>::value>::type,
+            typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
+            _VSTD::forward_as_tuple(
+                _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
+                _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...),
+            _VSTD::forward<_Tuple1>(__t1), _VSTD::forward<_Tuples>(__tpls)...);
+    }
+};
+
+template <class _Tuple0, class... _Tuples>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+typename __tuple_cat_return<_Tuple0, _Tuples...>::type
+tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
+{
+    typedef _LIBCPP_NODEBUG typename remove_reference<_Tuple0>::type _T0;
+    return __tuple_cat<tuple<>, __tuple_indices<>,
+                  typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
+                  (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
+                                            _VSTD::forward<_Tuples>(__tpls)...);
+}
+
+template <class ..._Tp, class _Alloc>
+struct _LIBCPP_TEMPLATE_VIS uses_allocator<tuple<_Tp...>, _Alloc>
+    : true_type {};
+
+template <class _T1, class _T2>
+template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+pair<_T1, _T2>::pair(piecewise_construct_t,
+                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
+                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
+    :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
+      second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
+{
+    (void)__first_args;
+    (void)__second_args;
+}
+
+#if _LIBCPP_STD_VER > 14
+template <class _Tp>
+inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
+
+#define _LIBCPP_NOEXCEPT_RETURN(...) noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
+
+template <class _Fn, class _Tuple, size_t ..._Id>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr decltype(auto) __apply_tuple_impl(_Fn && __f, _Tuple && __t,
+                                            __tuple_indices<_Id...>)
+_LIBCPP_NOEXCEPT_RETURN(
+    _VSTD::__invoke_constexpr(
+        _VSTD::forward<_Fn>(__f),
+        _VSTD::get<_Id>(_VSTD::forward<_Tuple>(__t))...)
+)
+
+template <class _Fn, class _Tuple>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr decltype(auto) apply(_Fn && __f, _Tuple && __t)
+_LIBCPP_NOEXCEPT_RETURN(
+    _VSTD::__apply_tuple_impl(
+        _VSTD::forward<_Fn>(__f), _VSTD::forward<_Tuple>(__t),
+        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
+)
+
+template <class _Tp, class _Tuple, size_t... _Idx>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>)
+_LIBCPP_NOEXCEPT_RETURN(
+    _Tp(_VSTD::get<_Idx>(_VSTD::forward<_Tuple>(__t))...)
+)
+
+template <class _Tp, class _Tuple>
+inline _LIBCPP_INLINE_VISIBILITY
+constexpr _Tp make_from_tuple(_Tuple&& __t)
+_LIBCPP_NOEXCEPT_RETURN(
+    _VSTD::__make_from_tuple_impl<_Tp>(_VSTD::forward<_Tuple>(__t),
+        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
+)
+
+#undef _LIBCPP_NOEXCEPT_RETURN
+
+#endif // _LIBCPP_STD_VER > 14
+
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_TUPLE