diff --git a/libcxx/include/__tuple b/libcxx/include/__tuple
deleted file mode 100644
index f85036e7af1db91b6985270d3196e8b924f12f01..0000000000000000000000000000000000000000
--- a/libcxx/include/__tuple
+++ /dev/null
@@ -1,550 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// 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
-
-#include <__config>
-#include <cstddef>
-#include <type_traits>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
-
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size;
-
-#if !defined(_LIBCPP_CXX03_LANG)
-template <class _Tp, class...>
-using __enable_if_tuple_size_imp = _Tp;
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<
-    const _Tp,
-    __enable_if_t<!is_volatile<_Tp>::value>,
-    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
-    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<
-    volatile _Tp,
-    __enable_if_t<!is_const<_Tp>::value>,
-    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
-    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
-
-template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp<
-    const volatile _Tp,
-    integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
-    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
-
-#else
-template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
-template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
-template <class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
-#endif
-
-template <size_t _Ip, class _Tp> struct _LIBCPP_TEMPLATE_VIS tuple_element;
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const _Tp>
-{
-    typedef _LIBCPP_NODEBUG typename add_const<typename tuple_element<_Ip, _Tp>::type>::type type;
-};
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, volatile _Tp>
-{
-    typedef _LIBCPP_NODEBUG typename add_volatile<typename tuple_element<_Ip, _Tp>::type>::type type;
-};
-
-template <size_t _Ip, class _Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const volatile _Tp>
-{
-    typedef _LIBCPP_NODEBUG typename add_cv<typename tuple_element<_Ip, _Tp>::type>::type type;
-};
-
-template <class _Tp> struct __tuple_like : false_type {};
-
-template <class _Tp> struct __tuple_like<const _Tp> : public __tuple_like<_Tp> {};
-template <class _Tp> struct __tuple_like<volatile _Tp> : public __tuple_like<_Tp> {};
-template <class _Tp> struct __tuple_like<const volatile _Tp> : public __tuple_like<_Tp> {};
-
-// tuple specializations
-
-#ifndef _LIBCPP_CXX03_LANG
-
-template <size_t...> struct __tuple_indices {};
-
-template <class _IdxType, _IdxType... _Values>
-struct __integer_sequence {
-  template <template <class _OIdxType, _OIdxType...> class _ToIndexSeq, class _ToIndexType>
-  using __convert = _ToIndexSeq<_ToIndexType, _Values...>;
-
-  template <size_t _Sp>
-  using __to_tuple_indices = __tuple_indices<(_Values + _Sp)...>;
-};
-
-#if !__has_builtin(__make_integer_seq) || defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
-namespace __detail {
-
-template<typename _Tp, size_t ..._Extra> struct __repeat;
-template<typename _Tp, _Tp ..._Np, size_t ..._Extra> struct __repeat<__integer_sequence<_Tp, _Np...>, _Extra...> {
-  typedef _LIBCPP_NODEBUG __integer_sequence<_Tp,
-                           _Np...,
-                           sizeof...(_Np) + _Np...,
-                           2 * sizeof...(_Np) + _Np...,
-                           3 * sizeof...(_Np) + _Np...,
-                           4 * sizeof...(_Np) + _Np...,
-                           5 * sizeof...(_Np) + _Np...,
-                           6 * sizeof...(_Np) + _Np...,
-                           7 * sizeof...(_Np) + _Np...,
-                           _Extra...> type;
-};
-
-template<size_t _Np> struct __parity;
-template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};
-
-template<> struct __make<0> { typedef __integer_sequence<size_t> type; };
-template<> struct __make<1> { typedef __integer_sequence<size_t, 0> type; };
-template<> struct __make<2> { typedef __integer_sequence<size_t, 0, 1> type; };
-template<> struct __make<3> { typedef __integer_sequence<size_t, 0, 1, 2> type; };
-template<> struct __make<4> { typedef __integer_sequence<size_t, 0, 1, 2, 3> type; };
-template<> struct __make<5> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4> type; };
-template<> struct __make<6> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; };
-template<> struct __make<7> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; };
-
-template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
-template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
-template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
-template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
-template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
-template<> struct __parity<5> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
-template<> struct __parity<6> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
-template<> struct __parity<7> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 7, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
-
-} // namespace detail
-
-#endif // !__has_builtin(__make_integer_seq) || defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
-
-#if __has_builtin(__make_integer_seq)
-template <size_t _Ep, size_t _Sp>
-using __make_indices_imp =
-    typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template
-    __to_tuple_indices<_Sp>;
-#else
-template <size_t _Ep, size_t _Sp>
-using __make_indices_imp =
-    typename __detail::__make<_Ep - _Sp>::type::template __to_tuple_indices<_Sp>;
-
-#endif
-
-template <size_t _Ep, size_t _Sp = 0>
-struct __make_tuple_indices
-{
-    static_assert(_Sp <= _Ep, "__make_tuple_indices input error");
-    typedef __make_indices_imp<_Ep, _Sp> type;
-};
-
-
-template <class ..._Tp> class _LIBCPP_TEMPLATE_VIS tuple;
-
-template <class... _Tp> struct __tuple_like<tuple<_Tp...> > : true_type {};
-
-template <class ..._Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> >
-    : public integral_constant<size_t, sizeof...(_Tp)>
-{
-};
-
-template <size_t _Ip, class ..._Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-typename tuple_element<_Ip, tuple<_Tp...> >::type&
-get(tuple<_Tp...>&) _NOEXCEPT;
-
-template <size_t _Ip, class ..._Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const typename tuple_element<_Ip, tuple<_Tp...> >::type&
-get(const tuple<_Tp...>&) _NOEXCEPT;
-
-template <size_t _Ip, class ..._Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-typename tuple_element<_Ip, tuple<_Tp...> >::type&&
-get(tuple<_Tp...>&&) _NOEXCEPT;
-
-template <size_t _Ip, class ..._Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
-get(const tuple<_Tp...>&&) _NOEXCEPT;
-
-#endif // !defined(_LIBCPP_CXX03_LANG)
-
-// pair specializations
-
-template <class _T1, class _T2> struct __tuple_like<pair<_T1, _T2> > : true_type {};
-
-template <size_t _Ip, class _T1, class _T2>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-typename tuple_element<_Ip, pair<_T1, _T2> >::type&
-get(pair<_T1, _T2>&) _NOEXCEPT;
-
-template <size_t _Ip, class _T1, class _T2>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
-get(const pair<_T1, _T2>&) _NOEXCEPT;
-
-#ifndef _LIBCPP_CXX03_LANG
-template <size_t _Ip, class _T1, class _T2>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
-get(pair<_T1, _T2>&&) _NOEXCEPT;
-
-template <size_t _Ip, class _T1, class _T2>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
-get(const pair<_T1, _T2>&&) _NOEXCEPT;
-#endif
-
-// array specializations
-
-template <class _Tp, size_t _Size> struct _LIBCPP_TEMPLATE_VIS array;
-
-template <class _Tp, size_t _Size> struct __tuple_like<array<_Tp, _Size> > : true_type {};
-
-template <size_t _Ip, class _Tp, size_t _Size>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp&
-get(array<_Tp, _Size>&) _NOEXCEPT;
-
-template <size_t _Ip, class _Tp, size_t _Size>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&
-get(const array<_Tp, _Size>&) _NOEXCEPT;
-
-#ifndef _LIBCPP_CXX03_LANG
-template <size_t _Ip, class _Tp, size_t _Size>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp&&
-get(array<_Tp, _Size>&&) _NOEXCEPT;
-
-template <size_t _Ip, class _Tp, size_t _Size>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
-const _Tp&&
-get(const array<_Tp, _Size>&&) _NOEXCEPT;
-#endif
-
-#ifndef _LIBCPP_CXX03_LANG
-
-// __tuple_types
-
-template <class ..._Tp> struct __tuple_types {};
-
-#if !__has_builtin(__type_pack_element)
-
-namespace __indexer_detail {
-
-template <size_t _Idx, class _Tp>
-struct __indexed { using type _LIBCPP_NODEBUG = _Tp; };
-
-template <class _Types, class _Indexes> struct __indexer;
-
-template <class ..._Types, size_t ..._Idx>
-struct __indexer<__tuple_types<_Types...>, __tuple_indices<_Idx...>>
-    : __indexed<_Idx, _Types>...
-{};
-
-template <size_t _Idx, class _Tp>
-__indexed<_Idx, _Tp> __at_index(__indexed<_Idx, _Tp> const&);
-
-} // namespace __indexer_detail
-
-template <size_t _Idx, class ..._Types>
-using __type_pack_element _LIBCPP_NODEBUG = typename decltype(
-    __indexer_detail::__at_index<_Idx>(
-        __indexer_detail::__indexer<
-            __tuple_types<_Types...>,
-            typename __make_tuple_indices<sizeof...(_Types)>::type
-        >{})
-  )::type;
-#endif
-
-template <size_t _Ip, class ..._Types>
-struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, __tuple_types<_Types...> >
-{
-    static_assert(_Ip < sizeof...(_Types), "tuple_element index out of range");
-    typedef _LIBCPP_NODEBUG __type_pack_element<_Ip, _Types...> type;
-};
-
-
-template <class ..._Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> >
-    : public integral_constant<size_t, sizeof...(_Tp)>
-{
-};
-
-template <class... _Tp> struct __tuple_like<__tuple_types<_Tp...> > : true_type {};
-
-template <bool _ApplyLV, bool _ApplyConst, bool _ApplyVolatile>
-struct __apply_cv_mf;
-template <>
-struct __apply_cv_mf<false, false, false> {
-  template <class _Tp> using __apply = _Tp;
-};
-template <>
-struct __apply_cv_mf<false, true, false> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = const _Tp;
-};
-template <>
-struct __apply_cv_mf<false, false, true> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = volatile _Tp;
-};
-template <>
-struct __apply_cv_mf<false, true, true> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = const volatile _Tp;
-};
-template <>
-struct __apply_cv_mf<true, false, false> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = _Tp&;
-};
-template <>
-struct __apply_cv_mf<true, true, false> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = const _Tp&;
-};
-template <>
-struct __apply_cv_mf<true, false, true> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = volatile _Tp&;
-};
-template <>
-struct __apply_cv_mf<true, true, true> {
-  template <class _Tp> using __apply _LIBCPP_NODEBUG = const volatile _Tp&;
-};
-template <class _Tp, class _RawTp = typename remove_reference<_Tp>::type>
-using __apply_cv_t _LIBCPP_NODEBUG = __apply_cv_mf<
-    is_lvalue_reference<_Tp>::value,
-    is_const<_RawTp>::value,
-    is_volatile<_RawTp>::value>;
-
-// __make_tuple_types
-
-// __make_tuple_types<_Tuple<_Types...>, _Ep, _Sp>::type is a
-// __tuple_types<_Types...> using only those _Types in the range [_Sp, _Ep).
-// _Sp defaults to 0 and _Ep defaults to tuple_size<_Tuple>.  If _Tuple is a
-// lvalue_reference type, then __tuple_types<_Types&...> is the result.
-
-template <class _TupleTypes, class _TupleIndices>
-struct __make_tuple_types_flat;
-
-template <template <class...> class _Tuple, class ..._Types, size_t ..._Idx>
-struct __make_tuple_types_flat<_Tuple<_Types...>, __tuple_indices<_Idx...>> {
-  // Specialization for pair, tuple, and __tuple_types
-  template <class _Tp, class _ApplyFn = __apply_cv_t<_Tp>>
-  using __apply_quals _LIBCPP_NODEBUG = __tuple_types<
-      typename _ApplyFn::template __apply<__type_pack_element<_Idx, _Types...>>...
-    >;
-};
-
-template <class _Vt, size_t _Np, size_t ..._Idx>
-struct __make_tuple_types_flat<array<_Vt, _Np>, __tuple_indices<_Idx...>> {
-  template <size_t>
-  using __value_type = _Vt;
-  template <class _Tp, class _ApplyFn = __apply_cv_t<_Tp>>
-  using __apply_quals = __tuple_types<
-      typename _ApplyFn::template __apply<__value_type<_Idx>>...
-    >;
-};
-
-template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value,
-          size_t _Sp = 0,
-          bool _SameSize = (_Ep == tuple_size<typename remove_reference<_Tp>::type>::value)>
-struct __make_tuple_types
-{
-    static_assert(_Sp <= _Ep, "__make_tuple_types input error");
-    using _RawTp = typename remove_cv<typename remove_reference<_Tp>::type>::type;
-    using _Maker = __make_tuple_types_flat<_RawTp, typename __make_tuple_indices<_Ep, _Sp>::type>;
-    using type = typename _Maker::template __apply_quals<_Tp>;
-};
-
-template <class ..._Types, size_t _Ep>
-struct __make_tuple_types<tuple<_Types...>, _Ep, 0, true> {
-  typedef _LIBCPP_NODEBUG __tuple_types<_Types...> type;
-};
-
-template <class ..._Types, size_t _Ep>
-struct __make_tuple_types<__tuple_types<_Types...>, _Ep, 0, true> {
-  typedef _LIBCPP_NODEBUG __tuple_types<_Types...> type;
-};
-
-template <bool ..._Preds>
-struct __all_dummy;
-
-template <bool ..._Pred>
-struct __all : _IsSame<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)...>> {};
-
-struct __tuple_sfinae_base {
-  template <template <class, class...> class _Trait,
-            class ..._LArgs, class ..._RArgs>
-  static auto __do_test(__tuple_types<_LArgs...>, __tuple_types<_RArgs...>)
-    -> __all<__enable_if_t<_Trait<_LArgs, _RArgs>::value, bool>{true}...>;
-  template <template <class...> class>
-  static auto __do_test(...) -> false_type;
-
-  template <class _FromArgs, class _ToArgs>
-  using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
-  template <class _FromArgs, class _ToArgs>
-  using __convertible = decltype(__do_test<is_convertible>(_FromArgs{}, _ToArgs{}));
-  template <class _FromArgs, class _ToArgs>
-  using __assignable = decltype(__do_test<is_assignable>(_ToArgs{}, _FromArgs{}));
-};
-
-// __tuple_convertible
-
-template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
-                                bool = __tuple_like<_Up>::value>
-struct __tuple_convertible
-    : public false_type {};
-
-template <class _Tp, class _Up>
-struct __tuple_convertible<_Tp, _Up, true, true>
-    : public __tuple_sfinae_base::__convertible<
-      typename __make_tuple_types<_Tp>::type
-    , typename __make_tuple_types<_Up>::type
-    >
-{};
-
-// __tuple_constructible
-
-template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
-                                bool = __tuple_like<_Up>::value>
-struct __tuple_constructible
-    : public false_type {};
-
-template <class _Tp, class _Up>
-struct __tuple_constructible<_Tp, _Up, true, true>
-    : public __tuple_sfinae_base::__constructible<
-      typename __make_tuple_types<_Tp>::type
-    , typename __make_tuple_types<_Up>::type
-    >
-{};
-
-// __tuple_assignable
-
-template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
-                                bool = __tuple_like<_Up>::value>
-struct __tuple_assignable
-    : public false_type {};
-
-template <class _Tp, class _Up>
-struct __tuple_assignable<_Tp, _Up, true, true>
-    : public __tuple_sfinae_base::__assignable<
-      typename __make_tuple_types<_Tp>::type
-    , typename __make_tuple_types<_Up&>::type
-    >
-{};
-
-
-template <size_t _Ip, class ..._Tp>
-struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, tuple<_Tp...> >
-{
-    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
-};
-
-#if _LIBCPP_STD_VER > 11
-template <size_t _Ip, class ..._Tp>
-using tuple_element_t _LIBCPP_NODEBUG = typename tuple_element <_Ip, _Tp...>::type;
-#endif
-
-template <bool _IsTuple, class _SizeTrait, size_t _Expected>
-struct __tuple_like_with_size_imp : false_type {};
-
-template <class _SizeTrait, size_t _Expected>
-struct __tuple_like_with_size_imp<true, _SizeTrait, _Expected>
-    : integral_constant<bool, _SizeTrait::value == _Expected> {};
-
-template <class _Tuple, size_t _ExpectedSize, class _RawTuple = __uncvref_t<_Tuple> >
-using __tuple_like_with_size _LIBCPP_NODEBUG = __tuple_like_with_size_imp<
-                                   __tuple_like<_RawTuple>::value,
-                                   tuple_size<_RawTuple>, _ExpectedSize
-                              >;
-
-struct _LIBCPP_TYPE_VIS __check_tuple_constructor_fail {
-
-    static constexpr bool __enable_explicit_default() { return false; }
-    static constexpr bool __enable_implicit_default() { return false; }
-    template <class ...>
-    static constexpr bool __enable_explicit() { return false; }
-    template <class ...>
-    static constexpr bool __enable_implicit() { return false; }
-    template <class ...>
-    static constexpr bool __enable_assign() { return false; }
-};
-#endif // !defined(_LIBCPP_CXX03_LANG)
-
-#if _LIBCPP_STD_VER > 14
-
-template <bool _CanCopy, bool _CanMove>
-struct __sfinae_ctor_base {};
-template <>
-struct __sfinae_ctor_base<false, false> {
-  __sfinae_ctor_base() = default;
-  __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
-  __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
-};
-template <>
-struct __sfinae_ctor_base<true, false> {
-  __sfinae_ctor_base() = default;
-  __sfinae_ctor_base(__sfinae_ctor_base const&) = default;
-  __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
-};
-template <>
-struct __sfinae_ctor_base<false, true> {
-  __sfinae_ctor_base() = default;
-  __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
-  __sfinae_ctor_base(__sfinae_ctor_base &&) = default;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
-  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
-};
-
-template <bool _CanCopy, bool _CanMove>
-struct __sfinae_assign_base {};
-template <>
-struct __sfinae_assign_base<false, false> {
-  __sfinae_assign_base() = default;
-  __sfinae_assign_base(__sfinae_assign_base const&) = default;
-  __sfinae_assign_base(__sfinae_assign_base &&) = default;
-  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
-  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
-};
-template <>
-struct __sfinae_assign_base<true, false> {
-  __sfinae_assign_base() = default;
-  __sfinae_assign_base(__sfinae_assign_base const&) = default;
-  __sfinae_assign_base(__sfinae_assign_base &&) = default;
-  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
-  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
-};
-template <>
-struct __sfinae_assign_base<false, true> {
-  __sfinae_assign_base() = default;
-  __sfinae_assign_base(__sfinae_assign_base const&) = default;
-  __sfinae_assign_base(__sfinae_assign_base &&) = default;
-  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
-  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = default;
-};
-#endif // _LIBCPP_STD_VER > 14
-
-_LIBCPP_END_NAMESPACE_STD
-
-#endif // _LIBCPP___TUPLE
diff --git a/libcxx/include/__tuple/find_index.h b/libcxx/include/__tuple/find_index.h
new file mode 100644
index 0000000000000000000000000000000000000000..133b00419d0c6ca15111230c27b4f83e399e22d5
--- /dev/null
+++ b/libcxx/include/__tuple/find_index.h
@@ -0,0 +1,62 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_FIND_INDEX_H
+#define _LIBCPP___TUPLE_FIND_INDEX_H
+
+#include <__config>
+#include <__type_traits/is_same.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 14
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace __find_detail {
+
+static constexpr size_t __not_found = static_cast<size_t>(-1);
+static constexpr size_t __ambiguous = __not_found - 1;
+
+inline _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {
+  return __i == _Nx
+           ? __not_found
+           : __find_detail::__find_idx_return(__i, __find_detail::__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...> {};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 14
+
+#endif // _LIBCPP___TUPLE_FIND_INDEX_H
diff --git a/libcxx/include/__tuple/ignore.h b/libcxx/include/__tuple/ignore.h
new file mode 100644
index 0000000000000000000000000000000000000000..43cce5387411bed14ea3d07f19d20c34c5e3b05b
--- /dev/null
+++ b/libcxx/include/__tuple/ignore.h
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_IGNORE_H
+#define _LIBCPP___TUPLE_IGNORE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct __ignore_type {
+  template <class _Tp>
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const __ignore_type& operator=(const _Tp&) const noexcept {
+    return *this;
+  }
+};
+
+#  if _LIBCPP_STD_VER >= 17
+inline constexpr __ignore_type ignore;
+#  else
+constexpr __ignore_type ignore;
+#  endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_CXX03_LANG
+
+#endif // _LIBCPP___TUPLE_IGNORE_H
diff --git a/libcxx/include/__tuple/make_tuple_types.h b/libcxx/include/__tuple/make_tuple_types.h
new file mode 100644
index 0000000000000000000000000000000000000000..9e0fefae2f2f58a22abb4fbc00310ae2972b4343
--- /dev/null
+++ b/libcxx/include/__tuple/make_tuple_types.h
@@ -0,0 +1,80 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_MAKE_TUPLE_TYPES_H
+#define _LIBCPP___TUPLE_MAKE_TUPLE_TYPES_H
+
+#include <__config>
+#include <__fwd/array.h>
+#include <__fwd/tuple.h>
+#include <__tuple/tuple_element.h>
+#include <__tuple/tuple_indices.h>
+#include <__tuple/tuple_size.h>
+#include <__tuple/tuple_types.h>
+#include <__type_traits/copy_cvref.h>
+#include <__type_traits/remove_cv.h>
+#include <__type_traits/remove_reference.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// __make_tuple_types<_Tuple<_Types...>, _Ep, _Sp>::type is a
+// __tuple_types<_Types...> using only those _Types in the range [_Sp, _Ep).
+// _Sp defaults to 0 and _Ep defaults to tuple_size<_Tuple>.  If _Tuple is a
+// lvalue_reference type, then __tuple_types<_Types&...> is the result.
+
+template <class _TupleTypes, class _TupleIndices>
+struct __make_tuple_types_flat;
+
+template <template <class...> class _Tuple, class... _Types, size_t... _Idx>
+struct __make_tuple_types_flat<_Tuple<_Types...>, __tuple_indices<_Idx...>> {
+  // Specialization for pair, tuple, and __tuple_types
+  template <class _Tp>
+  using __apply_quals _LIBCPP_NODEBUG = __tuple_types<__copy_cvref_t<_Tp, __type_pack_element<_Idx, _Types...>>...>;
+};
+
+template <class _Vt, size_t _Np, size_t... _Idx>
+struct __make_tuple_types_flat<array<_Vt, _Np>, __tuple_indices<_Idx...>> {
+  template <size_t>
+  using __value_type = _Vt;
+  template <class _Tp>
+  using __apply_quals = __tuple_types<__copy_cvref_t<_Tp, __value_type<_Idx>>...>;
+};
+
+template <class _Tp,
+          size_t _Ep     = tuple_size<__libcpp_remove_reference_t<_Tp> >::value,
+          size_t _Sp     = 0,
+          bool _SameSize = (_Ep == tuple_size<__libcpp_remove_reference_t<_Tp> >::value)>
+struct __make_tuple_types {
+  static_assert(_Sp <= _Ep, "__make_tuple_types input error");
+  using _RawTp = __remove_cv_t<__libcpp_remove_reference_t<_Tp> >;
+  using _Maker = __make_tuple_types_flat<_RawTp, typename __make_tuple_indices<_Ep, _Sp>::type>;
+  using type   = typename _Maker::template __apply_quals<_Tp>;
+};
+
+template <class... _Types, size_t _Ep>
+struct __make_tuple_types<tuple<_Types...>, _Ep, 0, true> {
+  typedef _LIBCPP_NODEBUG __tuple_types<_Types...> type;
+};
+
+template <class... _Types, size_t _Ep>
+struct __make_tuple_types<__tuple_types<_Types...>, _Ep, 0, true> {
+  typedef _LIBCPP_NODEBUG __tuple_types<_Types...> type;
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_CXX03_LANG
+
+#endif // _LIBCPP___TUPLE_MAKE_TUPLE_TYPES_H
diff --git a/libcxx/include/__tuple/sfinae_helpers.h b/libcxx/include/__tuple/sfinae_helpers.h
new file mode 100644
index 0000000000000000000000000000000000000000..c7145e0b011a999977e7c2103f715657a22f8cf9
--- /dev/null
+++ b/libcxx/include/__tuple/sfinae_helpers.h
@@ -0,0 +1,142 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_SFINAE_HELPERS_H
+#define _LIBCPP___TUPLE_SFINAE_HELPERS_H
+
+#include <__config>
+#include <__fwd/tuple.h>
+#include <__tuple/make_tuple_types.h>
+#include <__tuple/tuple_element.h>
+#include <__tuple/tuple_like_ext.h>
+#include <__tuple/tuple_size.h>
+#include <__tuple/tuple_types.h>
+#include <__type_traits/conjunction.h>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/integral_constant.h>
+#include <__type_traits/is_constructible.h>
+#include <__type_traits/is_same.h>
+#include <__type_traits/remove_cvref.h>
+#include <__type_traits/remove_reference.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_CXX03_LANG
+
+struct __tuple_sfinae_base {
+  template <template <class, class...> class _Trait, class... _LArgs, class... _RArgs>
+  static auto __do_test(__tuple_types<_LArgs...>,
+                        __tuple_types<_RArgs...>) -> __all<__enable_if_t<_Trait<_LArgs, _RArgs>::value, bool>{true}...>;
+  template <template <class...> class>
+  static auto __do_test(...) -> false_type;
+
+  template <class _FromArgs, class _ToArgs>
+  using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
+};
+
+// __tuple_constructible
+
+template <class _Tp,
+          class _Up,
+          bool = __tuple_like_ext<__libcpp_remove_reference_t<_Tp> >::value,
+          bool = __tuple_like_ext<_Up>::value>
+struct __tuple_constructible : public false_type {};
+
+template <class _Tp, class _Up>
+struct __tuple_constructible<_Tp, _Up, true, true>
+    : public __tuple_sfinae_base::__constructible< typename __make_tuple_types<_Tp>::type,
+                                                   typename __make_tuple_types<_Up>::type > {};
+
+template <size_t _Ip, class... _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, tuple<_Tp...> > {
+  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
+};
+
+struct _LIBCPP_EXPORTED_FROM_ABI __check_tuple_constructor_fail {
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit_default() { return false; }
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit_default() { return false; }
+  template <class...>
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_explicit() {
+    return false;
+  }
+  template <class...>
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_implicit() {
+    return false;
+  }
+  template <class...>
+  static _LIBCPP_HIDE_FROM_ABI constexpr bool __enable_assign() {
+    return false;
+  }
+};
+#endif // !defined(_LIBCPP_CXX03_LANG)
+
+#if _LIBCPP_STD_VER >= 17
+
+template <bool _CanCopy, bool _CanMove>
+struct __sfinae_ctor_base {};
+template <>
+struct __sfinae_ctor_base<false, false> {
+  __sfinae_ctor_base()                                     = default;
+  __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
+  __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
+};
+template <>
+struct __sfinae_ctor_base<true, false> {
+  __sfinae_ctor_base()                                     = default;
+  __sfinae_ctor_base(__sfinae_ctor_base const&)            = default;
+  __sfinae_ctor_base(__sfinae_ctor_base&&)                 = delete;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
+};
+template <>
+struct __sfinae_ctor_base<false, true> {
+  __sfinae_ctor_base()                                     = default;
+  __sfinae_ctor_base(__sfinae_ctor_base const&)            = delete;
+  __sfinae_ctor_base(__sfinae_ctor_base&&)                 = default;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
+  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&)      = default;
+};
+
+template <bool _CanCopy, bool _CanMove>
+struct __sfinae_assign_base {};
+template <>
+struct __sfinae_assign_base<false, false> {
+  __sfinae_assign_base()                                       = default;
+  __sfinae_assign_base(__sfinae_assign_base const&)            = default;
+  __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
+  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
+  __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
+};
+template <>
+struct __sfinae_assign_base<true, false> {
+  __sfinae_assign_base()                                       = default;
+  __sfinae_assign_base(__sfinae_assign_base const&)            = default;
+  __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
+  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
+  __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = delete;
+};
+template <>
+struct __sfinae_assign_base<false, true> {
+  __sfinae_assign_base()                                       = default;
+  __sfinae_assign_base(__sfinae_assign_base const&)            = default;
+  __sfinae_assign_base(__sfinae_assign_base&&)                 = default;
+  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
+  __sfinae_assign_base& operator=(__sfinae_assign_base&&)      = default;
+};
+#endif // _LIBCPP_STD_VER >= 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_SFINAE_HELPERS_H
diff --git a/libcxx/include/__tuple/tuple_element.h b/libcxx/include/__tuple/tuple_element.h
new file mode 100644
index 0000000000000000000000000000000000000000..9127c47dc8f1a5f04a888875cfc0ecee8b1750c6
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_element.h
@@ -0,0 +1,58 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_ELEMENT_H
+#define _LIBCPP___TUPLE_TUPLE_ELEMENT_H
+
+#include <__config>
+#include <__tuple/tuple_indices.h>
+#include <__tuple/tuple_types.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <size_t _Ip, class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_element;
+
+template <size_t _Ip, class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const _Tp> {
+  typedef _LIBCPP_NODEBUG const typename tuple_element<_Ip, _Tp>::type type;
+};
+
+template <size_t _Ip, class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, volatile _Tp> {
+  typedef _LIBCPP_NODEBUG volatile typename tuple_element<_Ip, _Tp>::type type;
+};
+
+template <size_t _Ip, class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, const volatile _Tp> {
+  typedef _LIBCPP_NODEBUG const volatile typename tuple_element<_Ip, _Tp>::type type;
+};
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <size_t _Ip, class... _Types>
+struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, __tuple_types<_Types...> > {
+  static_assert(_Ip < sizeof...(_Types), "tuple_element index out of range");
+  typedef _LIBCPP_NODEBUG __type_pack_element<_Ip, _Types...> type;
+};
+
+#  if _LIBCPP_STD_VER >= 14
+template <size_t _Ip, class... _Tp>
+using tuple_element_t _LIBCPP_NODEBUG = typename tuple_element<_Ip, _Tp...>::type;
+#  endif
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_ELEMENT_H
diff --git a/libcxx/include/__tuple/tuple_indices.h b/libcxx/include/__tuple/tuple_indices.h
new file mode 100644
index 0000000000000000000000000000000000000000..501e711255ec1001bc60915388e412780f717580
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_indices.h
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_MAKE_TUPLE_INDICES_H
+#define _LIBCPP___TUPLE_MAKE_TUPLE_INDICES_H
+
+#include <__config>
+#include <__utility/integer_sequence.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <size_t...>
+struct __tuple_indices {};
+
+template <size_t _Ep, size_t _Sp = 0>
+struct __make_tuple_indices {
+  static_assert(_Sp <= _Ep, "__make_tuple_indices input error");
+  typedef __make_indices_imp<_Ep, _Sp> type;
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_CXX03_LANG
+
+#endif // _LIBCPP___TUPLE_MAKE_TUPLE_INDICES_H
diff --git a/libcxx/include/__tuple/tuple_like.h b/libcxx/include/__tuple/tuple_like.h
new file mode 100644
index 0000000000000000000000000000000000000000..c080a3dcf1e258a29d3b4a7c9293b12ca1642da3
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_like.h
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_LIKE_H
+#define _LIBCPP___TUPLE_TUPLE_LIKE_H
+
+#include <__config>
+#include <__fwd/subrange.h>
+#include <__tuple/tuple_like_no_subrange.h>
+#include <__tuple/tuple_size.h>
+#include <__type_traits/remove_cvref.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <class _Tp>
+inline constexpr bool __is_ranges_subrange_v = false;
+
+template <class _Iter, class _Sent, ranges::subrange_kind _Kind>
+inline constexpr bool __is_ranges_subrange_v<ranges::subrange<_Iter, _Sent, _Kind>> = true;
+
+template <class _Tp>
+concept __tuple_like = __tuple_like_no_subrange<_Tp> || __is_ranges_subrange_v<remove_cvref_t<_Tp>>;
+
+// As of writing this comment every use of `pair-like` in the standard excludes `ranges::subrange`, so
+// you most likely want to use `__pair_like_no_subrange` if you're looking for `pair-like`.
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_LIKE_H
diff --git a/libcxx/include/__tuple/tuple_like_ext.h b/libcxx/include/__tuple/tuple_like_ext.h
new file mode 100644
index 0000000000000000000000000000000000000000..0cc21e0b75fd1ae61ba6fda2ed7d565a13ad97ca
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_like_ext.h
@@ -0,0 +1,52 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_LIKE_EXT_H
+#define _LIBCPP___TUPLE_TUPLE_LIKE_EXT_H
+
+#include <__config>
+#include <__fwd/array.h>
+#include <__fwd/pair.h>
+#include <__fwd/tuple.h>
+#include <__tuple/tuple_types.h>
+#include <__type_traits/integral_constant.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp>
+struct __tuple_like_ext : false_type {};
+
+template <class _Tp>
+struct __tuple_like_ext<const _Tp> : public __tuple_like_ext<_Tp> {};
+template <class _Tp>
+struct __tuple_like_ext<volatile _Tp> : public __tuple_like_ext<_Tp> {};
+template <class _Tp>
+struct __tuple_like_ext<const volatile _Tp> : public __tuple_like_ext<_Tp> {};
+
+#ifndef _LIBCPP_CXX03_LANG
+template <class... _Tp>
+struct __tuple_like_ext<tuple<_Tp...> > : true_type {};
+#endif
+
+template <class _T1, class _T2>
+struct __tuple_like_ext<pair<_T1, _T2> > : true_type {};
+
+template <class _Tp, size_t _Size>
+struct __tuple_like_ext<array<_Tp, _Size> > : true_type {};
+
+template <class... _Tp>
+struct __tuple_like_ext<__tuple_types<_Tp...> > : true_type {};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_LIKE_EXT_H
diff --git a/libcxx/include/__tuple/tuple_like_no_subrange.h b/libcxx/include/__tuple/tuple_like_no_subrange.h
new file mode 100644
index 0000000000000000000000000000000000000000..274b0bf188e1f492c48bd06c3bb39f33f821d465
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_like_no_subrange.h
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_LIKE_NO_SUBRANGE_H
+#define _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
+
+#include <__config>
+#include <__fwd/array.h>
+#include <__fwd/complex.h>
+#include <__fwd/pair.h>
+#include <__fwd/tuple.h>
+#include <__tuple/tuple_size.h>
+#include <__type_traits/remove_cvref.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+template <class _Tp>
+inline constexpr bool __tuple_like_no_subrange_impl = false;
+
+template <class... _Tp>
+inline constexpr bool __tuple_like_no_subrange_impl<tuple<_Tp...>> = true;
+
+template <class _T1, class _T2>
+inline constexpr bool __tuple_like_no_subrange_impl<pair<_T1, _T2>> = true;
+
+template <class _Tp, size_t _Size>
+inline constexpr bool __tuple_like_no_subrange_impl<array<_Tp, _Size>> = true;
+
+#  if _LIBCPP_STD_VER >= 26
+
+template <class _Tp>
+inline constexpr bool __tuple_like_no_subrange_impl<complex<_Tp>> = true;
+
+#  endif
+
+template <class _Tp>
+concept __tuple_like_no_subrange = __tuple_like_no_subrange_impl<remove_cvref_t<_Tp>>;
+
+// This is equivalent to the exposition-only type trait `pair-like`, except that it is false for specializations of
+// `ranges::subrange`. This is more useful than the pair-like concept in the standard because every use of `pair-like`
+// excludes `ranges::subrange`.
+template <class _Tp>
+concept __pair_like_no_subrange = __tuple_like_no_subrange<_Tp> && tuple_size<remove_cvref_t<_Tp>>::value == 2;
+
+#endif // _LIBCPP_STD_VER >= 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
diff --git a/libcxx/include/__tuple/tuple_size.h b/libcxx/include/__tuple/tuple_size.h
new file mode 100644
index 0000000000000000000000000000000000000000..18a17fd4d58780b8cc19416fda4809598d50e8b1
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_size.h
@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_SIZE_H
+#define _LIBCPP___TUPLE_TUPLE_SIZE_H
+
+#include <__config>
+#include <__fwd/tuple.h>
+#include <__tuple/tuple_types.h>
+#include <__type_traits/is_const.h>
+#include <__type_traits/is_volatile.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size;
+
+#if !defined(_LIBCPP_CXX03_LANG)
+template <class _Tp, class...>
+using __enable_if_tuple_size_imp = _Tp;
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< const _Tp,
+                                                                   __enable_if_t<!is_volatile<_Tp>::value>,
+                                                                   integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
+    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<__enable_if_tuple_size_imp< volatile _Tp,
+                                                                   __enable_if_t<!is_const<_Tp>::value>,
+                                                                   integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
+    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
+
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS
+tuple_size<__enable_if_tuple_size_imp<const volatile _Tp, integral_constant<size_t, sizeof(tuple_size<_Tp>)>>>
+    : public integral_constant<size_t, tuple_size<_Tp>::value> {};
+
+#else
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<const _Tp> : public tuple_size<_Tp> {};
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<volatile _Tp> : public tuple_size<_Tp> {};
+template <class _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<const volatile _Tp> : public tuple_size<_Tp> {};
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <class... _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<tuple<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
+
+template <class... _Tp>
+struct _LIBCPP_TEMPLATE_VIS tuple_size<__tuple_types<_Tp...> > : public integral_constant<size_t, sizeof...(_Tp)> {};
+
+#  if _LIBCPP_STD_VER >= 17
+template <class _Tp>
+inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
+#  endif
+
+#endif // _LIBCPP_CXX03_LANG
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_SIZE_H
diff --git a/libcxx/include/__tuple/tuple_types.h b/libcxx/include/__tuple/tuple_types.h
new file mode 100644
index 0000000000000000000000000000000000000000..7e1256cf8790e18f1ff741c5d2fbb3541625eab9
--- /dev/null
+++ b/libcxx/include/__tuple/tuple_types.h
@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_TUPLE_TYPES_H
+#define _LIBCPP___TUPLE_TUPLE_TYPES_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class... _Tp>
+struct __tuple_types {};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___TUPLE_TUPLE_TYPES_H