#pragma once
#ifdef ARDUINO_ARCH_AVR
// <tuple> -*- C++ -*-

// Copyright (C) 2007-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file include/tuple
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_TUPLE
#define _GLIBCXX_TUPLE 1

#pragma GCC system_header

#if __cplusplus < 201103L
#include <bits/c++0x_warning.h>
#else

#include <bits/stl_pair.h>		 // for std::pair
#include <bits/uses_allocator.h> // for std::allocator_arg_t
#include <bits/invoke.h>		 // for std::__invoke
#if __cplusplus > 201703L
#include <compare>
#include <bits/ranges_util.h> // for std::ranges::subrange
#endif
#include <utility>

#define __glibcxx_want_constexpr_tuple
#define __glibcxx_want_tuple_element_t
#define __glibcxx_want_tuples_by_type
#define __glibcxx_want_apply
#define __glibcxx_want_make_from_tuple
#define __glibcxx_want_ranges_zip
#define __glibcxx_want_tuple_like
#define __glibcxx_want_constrained_equality
#include <bits/version.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION

	/**
	 *  @addtogroup utilities
	 *  @{
	 */

	template <typename... _Elements>
	class tuple;

	template <typename _Tp>
	struct __is_empty_non_tuple : is_empty<_Tp>
	{
	};

	// Using EBO for elements that are tuples causes ambiguous base errors.
	template <typename _El0, typename... _El>
	struct __is_empty_non_tuple<tuple<_El0, _El...>> : false_type
	{
	};

	// Use the Empty Base-class Optimization for empty, non-final types.
	template <typename _Tp>
	using __empty_not_final = __conditional_t<__is_final(_Tp), false_type,
											  __is_empty_non_tuple<_Tp>>;

	template <size_t _Idx, typename _Head,
			  bool = __empty_not_final<_Head>::value>
	struct _Head_base;

#if __has_cpp_attribute(__no_unique_address__)
	template <size_t _Idx, typename _Head>
	struct _Head_base<_Idx, _Head, true>
	{
		constexpr _Head_base()
			: _M_head_impl() {}

		constexpr _Head_base(const _Head &__h)
			: _M_head_impl(__h) {}

		constexpr _Head_base(const _Head_base &) = default;
		constexpr _Head_base(_Head_base &&) = default;

		template <typename _UHead>
		constexpr _Head_base(_UHead &&__h)
			: _M_head_impl(std::forward<_UHead>(__h)) {}

		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc0)
			: _M_head_impl() {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
			: _M_head_impl(allocator_arg, *__a._M_a) {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
			: _M_head_impl(*__a._M_a) {}

		template <typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc0, _UHead &&__uhead)
			: _M_head_impl(std::forward<_UHead>(__uhead)) {}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc1<_Alloc> __a, _UHead &&__uhead)
			: _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
		{
		}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc2<_Alloc> __a, _UHead &&__uhead)
			: _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) {}

		static constexpr _Head &
		_M_head(_Head_base &__b) noexcept { return __b._M_head_impl; }

		static constexpr const _Head &
		_M_head(const _Head_base &__b) noexcept { return __b._M_head_impl; }

		[[__no_unique_address__]] _Head _M_head_impl;
	};
#else
	template <size_t _Idx, typename _Head>
	struct _Head_base<_Idx, _Head, true>
		: public _Head
	{
		constexpr _Head_base()
			: _Head() {}

		constexpr _Head_base(const _Head &__h)
			: _Head(__h) {}

		constexpr _Head_base(const _Head_base &) = default;
		constexpr _Head_base(_Head_base &&) = default;

		template <typename _UHead>
		constexpr _Head_base(_UHead &&__h)
			: _Head(std::forward<_UHead>(__h)) {}

		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc0)
			: _Head() {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
			: _Head(allocator_arg, *__a._M_a) {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
			: _Head(*__a._M_a) {}

		template <typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc0, _UHead &&__uhead)
			: _Head(std::forward<_UHead>(__uhead)) {}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc1<_Alloc> __a, _UHead &&__uhead)
			: _Head(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead)) {}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc2<_Alloc> __a, _UHead &&__uhead)
			: _Head(std::forward<_UHead>(__uhead), *__a._M_a) {}

		static constexpr _Head &
		_M_head(_Head_base &__b) noexcept { return __b; }

		static constexpr const _Head &
		_M_head(const _Head_base &__b) noexcept { return __b; }
	};
#endif

	template <size_t _Idx, typename _Head>
	struct _Head_base<_Idx, _Head, false>
	{
		constexpr _Head_base()
			: _M_head_impl() {}

		constexpr _Head_base(const _Head &__h)
			: _M_head_impl(__h) {}

		constexpr _Head_base(const _Head_base &) = default;
		constexpr _Head_base(_Head_base &&) = default;

		template <typename _UHead>
		constexpr _Head_base(_UHead &&__h)
			: _M_head_impl(std::forward<_UHead>(__h)) {}

		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc0)
			: _M_head_impl() {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc1<_Alloc> __a)
			: _M_head_impl(allocator_arg, *__a._M_a) {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Head_base(allocator_arg_t, __uses_alloc2<_Alloc> __a)
			: _M_head_impl(*__a._M_a) {}

		template <typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc0, _UHead &&__uhead)
			: _M_head_impl(std::forward<_UHead>(__uhead)) {}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc1<_Alloc> __a, _UHead &&__uhead)
			: _M_head_impl(allocator_arg, *__a._M_a, std::forward<_UHead>(__uhead))
		{
		}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Head_base(__uses_alloc2<_Alloc> __a, _UHead &&__uhead)
			: _M_head_impl(std::forward<_UHead>(__uhead), *__a._M_a) {}

		static constexpr _Head &
		_M_head(_Head_base &__b) noexcept { return __b._M_head_impl; }

		static constexpr const _Head &
		_M_head(const _Head_base &__b) noexcept { return __b._M_head_impl; }

		_Head _M_head_impl;
	};

#if __cpp_lib_tuple_like // >= C++23
	struct __tuple_like_tag_t
	{
		explicit __tuple_like_tag_t() = default;
	};

	// This forward declaration is used by the operator<=> overload for
	// tuple-like types.
	template <typename _Cat, typename _Tp, typename _Up, typename _IndexSeq>
	constexpr _Cat
	__tuple_cmp(const _Tp &__t, const _Up &__u, _IndexSeq);
#endif					 // C++23

	/**
	 * Contains the actual implementation of the @c tuple template, stored
	 * as a recursive inheritance hierarchy from the first element (most
	 * derived class) to the last (least derived class). The @c Idx
	 * parameter gives the 0-based index of the element stored at this
	 * point in the hierarchy; we use it to implement a constant-time
	 * get() operation.
	 */
	template <size_t _Idx, typename... _Elements>
	struct _Tuple_impl;

	/**
	 * Recursive tuple implementation. Here we store the @c Head element
	 * and derive from a @c Tuple_impl containing the remaining elements
	 * (which contains the @c Tail).
	 */
	template <size_t _Idx, typename _Head, typename... _Tail>
	struct _Tuple_impl<_Idx, _Head, _Tail...>
		: public _Tuple_impl<_Idx + 1, _Tail...>,
		  private _Head_base<_Idx, _Head>
	{
		template <size_t, typename...>
		friend struct _Tuple_impl;

		typedef _Tuple_impl<_Idx + 1, _Tail...> _Inherited;
		typedef _Head_base<_Idx, _Head> _Base;

		static constexpr _Head &
		_M_head(_Tuple_impl &__t) noexcept { return _Base::_M_head(__t); }

		static constexpr const _Head &
		_M_head(const _Tuple_impl &__t) noexcept { return _Base::_M_head(__t); }

		static constexpr _Inherited &
		_M_tail(_Tuple_impl &__t) noexcept { return __t; }

		static constexpr const _Inherited &
		_M_tail(const _Tuple_impl &__t) noexcept { return __t; }

		constexpr _Tuple_impl()
			: _Inherited(), _Base() {}

		explicit constexpr _Tuple_impl(const _Head &__head, const _Tail &...__tail)
			: _Inherited(__tail...), _Base(__head)
		{
		}

		template <typename _UHead, typename... _UTail,
				  typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
		explicit constexpr _Tuple_impl(_UHead &&__head, _UTail &&...__tail)
			: _Inherited(std::forward<_UTail>(__tail)...),
			  _Base(std::forward<_UHead>(__head))
		{
		}

		constexpr _Tuple_impl(const _Tuple_impl &) = default;

		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 2729. Missing SFINAE on std::pair::operator=
		_Tuple_impl &operator=(const _Tuple_impl &) = delete;

		_Tuple_impl(_Tuple_impl &&) = default;

		template <typename... _UElements>
		constexpr _Tuple_impl(const _Tuple_impl<_Idx, _UElements...> &__in)
			: _Inherited(_Tuple_impl<_Idx, _UElements...>::_M_tail(__in)),
			  _Base(_Tuple_impl<_Idx, _UElements...>::_M_head(__in))
		{
		}

		template <typename _UHead, typename... _UTails>
		constexpr _Tuple_impl(_Tuple_impl<_Idx, _UHead, _UTails...> &&__in)
			: _Inherited(std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
			  _Base(std::forward<_UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
		{
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename... _UElements>
		constexpr _Tuple_impl(_Tuple_impl<_Idx, _UElements...> &__in)
			: _Inherited(_Tuple_impl<_Idx, _UElements...>::_M_tail(__in)),
			  _Base(_Tuple_impl<_Idx, _UElements...>::_M_head(__in))
		{
		}

		template <typename _UHead, typename... _UTails>
		constexpr _Tuple_impl(const _Tuple_impl<_Idx, _UHead, _UTails...> &&__in)
			: _Inherited(std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
			  _Base(std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
		{
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _UTuple, size_t... _Is>
		constexpr _Tuple_impl(__tuple_like_tag_t, _UTuple &&__u, index_sequence<_Is...>)
			: _Tuple_impl(std::get<_Is>(std::forward<_UTuple>(__u))...)
		{
		}
#endif					 // C++23

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a)
			: _Inherited(__tag, __a),
			  _Base(__tag, __use_alloc<_Head>(__a))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					const _Head &__head, const _Tail &...__tail)
			: _Inherited(__tag, __a, __tail...),
			  _Base(__use_alloc<_Head, _Alloc, _Head>(__a), __head)
		{
		}

		template <typename _Alloc, typename _UHead, typename... _UTail,
				  typename = __enable_if_t<sizeof...(_Tail) == sizeof...(_UTail)>>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					_UHead &&__head, _UTail &&...__tail)
			: _Inherited(__tag, __a, std::forward<_UTail>(__tail)...),
			  _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
					std::forward<_UHead>(__head))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					const _Tuple_impl &__in)
			: _Inherited(__tag, __a, _M_tail(__in)),
			  _Base(__use_alloc<_Head, _Alloc, _Head>(__a), _M_head(__in))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					_Tuple_impl &&__in)
			: _Inherited(__tag, __a, std::move(_M_tail(__in))),
			  _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
					std::forward<_Head>(_M_head(__in)))
		{
		}

		template <typename _Alloc, typename _UHead, typename... _UTails>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					const _Tuple_impl<_Idx, _UHead, _UTails...> &__in)
			: _Inherited(__tag, __a,
						 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)),
			  _Base(__use_alloc<_Head, _Alloc, const _UHead &>(__a),
					_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in))
		{
		}

		template <typename _Alloc, typename _UHead, typename... _UTails>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
					_Tuple_impl<_Idx, _UHead, _UTails...> &&__in)
			: _Inherited(__tag, __a, std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
			  _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
					std::forward<_UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
		{
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _Alloc, typename _UHead, typename... _UTails>
		constexpr _Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
							  _Tuple_impl<_Idx, _UHead, _UTails...> &__in)
			: _Inherited(__tag, __a,
						 _Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)),
			  _Base(__use_alloc<_Head, _Alloc, _UHead &>(__a),
					_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in))
		{
		}

		template <typename _Alloc, typename _UHead, typename... _UTails>
		constexpr _Tuple_impl(allocator_arg_t __tag, const _Alloc &__a,
							  const _Tuple_impl<_Idx, _UHead, _UTails...> &&__in)
			: _Inherited(__tag, __a, std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in))),
			  _Base(__use_alloc<_Head, _Alloc, const _UHead>(__a),
					std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in)))
		{
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _Alloc, typename _UTuple, size_t... _Is>
		constexpr _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc &__a,
							  _UTuple &&__u, index_sequence<_Is...>)
			: _Tuple_impl(__tag, __a, std::get<_Is>(std::forward<_UTuple>(__u))...)
		{
		}
#endif					 // C++23

		template <typename... _UElements>
		_GLIBCXX20_CONSTEXPR void
		_M_assign(const _Tuple_impl<_Idx, _UElements...> &__in)
		{
			_M_head(*this) = _Tuple_impl<_Idx, _UElements...>::_M_head(__in);
			_M_tail(*this)._M_assign(
				_Tuple_impl<_Idx, _UElements...>::_M_tail(__in));
		}

		template <typename _UHead, typename... _UTails>
		_GLIBCXX20_CONSTEXPR void
		_M_assign(_Tuple_impl<_Idx, _UHead, _UTails...> &&__in)
		{
			_M_head(*this) = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in));
			_M_tail(*this)._M_assign(
				std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)));
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename... _UElements>
		constexpr void
		_M_assign(const _Tuple_impl<_Idx, _UElements...> &__in) const
		{
			_M_head(*this) = _Tuple_impl<_Idx, _UElements...>::_M_head(__in);
			_M_tail(*this)._M_assign(
				_Tuple_impl<_Idx, _UElements...>::_M_tail(__in));
		}

		template <typename _UHead, typename... _UTails>
		constexpr void
		_M_assign(_Tuple_impl<_Idx, _UHead, _UTails...> &&__in) const
		{
			_M_head(*this) = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_head(__in));
			_M_tail(*this)._M_assign(
				std::move(_Tuple_impl<_Idx, _UHead, _UTails...>::_M_tail(__in)));
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _UTuple>
		constexpr void
		_M_assign(__tuple_like_tag_t __tag, _UTuple &&__u)
		{
			_M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
			_M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
		}

		template <typename _UTuple>
		constexpr void
		_M_assign(__tuple_like_tag_t __tag, _UTuple &&__u) const
		{
			_M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
			_M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
		}
#endif					 // C++23

	protected:
		_GLIBCXX20_CONSTEXPR
		void
		_M_swap(_Tuple_impl &__in)
		{
			using std::swap;
			swap(_M_head(*this), _M_head(__in));
			_Inherited::_M_swap(_M_tail(__in));
		}

#if __cpp_lib_ranges_zip // >= C++23
		constexpr void
		_M_swap(const _Tuple_impl &__in) const
		{
			using std::swap;
			swap(_M_head(*this), _M_head(__in));
			_Inherited::_M_swap(_M_tail(__in));
		}
#endif					 // C++23
	};

	// Basis case of inheritance recursion.
	template <size_t _Idx, typename _Head>
	struct _Tuple_impl<_Idx, _Head>
		: private _Head_base<_Idx, _Head>
	{
		template <size_t, typename...>
		friend struct _Tuple_impl;

		typedef _Head_base<_Idx, _Head> _Base;

		static constexpr _Head &
		_M_head(_Tuple_impl &__t) noexcept { return _Base::_M_head(__t); }

		static constexpr const _Head &
		_M_head(const _Tuple_impl &__t) noexcept { return _Base::_M_head(__t); }

		constexpr _Tuple_impl()
			: _Base() {}

		explicit constexpr _Tuple_impl(const _Head &__head)
			: _Base(__head)
		{
		}

		template <typename _UHead>
		explicit constexpr _Tuple_impl(_UHead &&__head)
			: _Base(std::forward<_UHead>(__head))
		{
		}

		constexpr _Tuple_impl(const _Tuple_impl &) = default;

		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 2729. Missing SFINAE on std::pair::operator=
		_Tuple_impl &operator=(const _Tuple_impl &) = delete;

#if _GLIBCXX_INLINE_VERSION
		_Tuple_impl(_Tuple_impl &&) = default;
#else
		constexpr _Tuple_impl(_Tuple_impl &&__in) noexcept(is_nothrow_move_constructible<_Head>::value)
			: _Base(static_cast<_Base &&>(__in))
		{
		}
#endif

		template <typename _UHead>
		constexpr _Tuple_impl(const _Tuple_impl<_Idx, _UHead> &__in)
			: _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in))
		{
		}

		template <typename _UHead>
		constexpr _Tuple_impl(_Tuple_impl<_Idx, _UHead> &&__in)
			: _Base(std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
		{
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _UHead>
		constexpr _Tuple_impl(_Tuple_impl<_Idx, _UHead> &__in)
			: _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in))
		{
		}

		template <typename _UHead>
		constexpr _Tuple_impl(const _Tuple_impl<_Idx, _UHead> &&__in)
			: _Base(std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
		{
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _UTuple>
		constexpr _Tuple_impl(__tuple_like_tag_t, _UTuple &&__u, index_sequence<0>)
			: _Tuple_impl(std::get<0>(std::forward<_UTuple>(__u)))
		{
		}
#endif					 // C++23

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t __tag, const _Alloc &__a)
			: _Base(__tag, __use_alloc<_Head>(__a))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					const _Head &__head)
			: _Base(__use_alloc<_Head, _Alloc, const _Head &>(__a), __head)
		{
		}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					_UHead &&__head)
			: _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
					std::forward<_UHead>(__head))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					const _Tuple_impl &__in)
			: _Base(__use_alloc<_Head, _Alloc, const _Head &>(__a), _M_head(__in))
		{
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					_Tuple_impl &&__in)
			: _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
					std::forward<_Head>(_M_head(__in)))
		{
		}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					const _Tuple_impl<_Idx, _UHead> &__in)
			: _Base(__use_alloc<_Head, _Alloc, const _UHead &>(__a),
					_Tuple_impl<_Idx, _UHead>::_M_head(__in))
		{
		}

		template <typename _Alloc, typename _UHead>
		_GLIBCXX20_CONSTEXPR
		_Tuple_impl(allocator_arg_t, const _Alloc &__a,
					_Tuple_impl<_Idx, _UHead> &&__in)
			: _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
					std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
		{
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _Alloc, typename _UHead>
		constexpr _Tuple_impl(allocator_arg_t, const _Alloc &__a,
							  _Tuple_impl<_Idx, _UHead> &__in)
			: _Base(__use_alloc<_Head, _Alloc, _UHead &>(__a),
					_Tuple_impl<_Idx, _UHead>::_M_head(__in))
		{
		}

		template <typename _Alloc, typename _UHead>
		constexpr _Tuple_impl(allocator_arg_t, const _Alloc &__a,
							  const _Tuple_impl<_Idx, _UHead> &&__in)
			: _Base(__use_alloc<_Head, _Alloc, const _UHead>(__a),
					std::forward<const _UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
		{
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _Alloc, typename _UTuple>
		constexpr _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc &__a,
							  _UTuple &&__u, index_sequence<0>)
			: _Tuple_impl(__tag, __a, std::get<0>(std::forward<_UTuple>(__u)))
		{
		}
#endif					 // C++23

		template <typename _UHead>
		_GLIBCXX20_CONSTEXPR void
		_M_assign(const _Tuple_impl<_Idx, _UHead> &__in)
		{
			_M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
		}

		template <typename _UHead>
		_GLIBCXX20_CONSTEXPR void
		_M_assign(_Tuple_impl<_Idx, _UHead> &&__in)
		{
			_M_head(*this) = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _UHead>
		constexpr void
		_M_assign(const _Tuple_impl<_Idx, _UHead> &__in) const
		{
			_M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
		}

		template <typename _UHead>
		constexpr void
		_M_assign(_Tuple_impl<_Idx, _UHead> &&__in) const
		{
			_M_head(*this) = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _UTuple>
		constexpr void
		_M_assign(__tuple_like_tag_t, _UTuple &&__u)
		{
			_M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
		}

		template <typename _UTuple>
		constexpr void
		_M_assign(__tuple_like_tag_t, _UTuple &&__u) const
		{
			_M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
		}
#endif					 // C++23

	protected:
		_GLIBCXX20_CONSTEXPR
		void
		_M_swap(_Tuple_impl &__in)
		{
			using std::swap;
			swap(_M_head(*this), _M_head(__in));
		}

#if __cpp_lib_ranges_zip // >= C++23
		constexpr void
		_M_swap(const _Tuple_impl &__in) const
		{
			using std::swap;
			swap(_M_head(*this), _M_head(__in));
		}
#endif					 // C++23
	};

	// Concept utility functions, reused in conditionally-explicit
	// constructors.
	template <bool, typename... _Types>
	struct _TupleConstraints
	{
		template <typename... _UTypes>
		using __constructible = __and_<is_constructible<_Types, _UTypes>...>;

		template <typename... _UTypes>
		using __convertible = __and_<is_convertible<_UTypes, _Types>...>;

		// Constraint for a non-explicit constructor.
		// True iff each Ti in _Types... can be constructed from Ui in _UTypes...
		// and every Ui is implicitly convertible to Ti.
		template <typename... _UTypes>
		static constexpr bool __is_implicitly_constructible()
		{
			return __and_<__constructible<_UTypes...>,
						  __convertible<_UTypes...>>::value;
		}

		// Constraint for a non-explicit constructor.
		// True iff each Ti in _Types... can be constructed from Ui in _UTypes...
		// but not every Ui is implicitly convertible to Ti.
		template <typename... _UTypes>
		static constexpr bool __is_explicitly_constructible()
		{
			return __and_<__constructible<_UTypes...>,
						  __not_<__convertible<_UTypes...>>>::value;
		}

		static constexpr bool __is_implicitly_default_constructible()
		{
			return __and_<std::__is_implicitly_default_constructible<_Types>...>::value;
		}

		static constexpr bool __is_explicitly_default_constructible()
		{
			return __and_<is_default_constructible<_Types>...,
						  __not_<__and_<
							  std::__is_implicitly_default_constructible<_Types>...>>>::value;
		}
	};

	// Partial specialization used when a required precondition isn't met,
	// e.g. when sizeof...(_Types) != sizeof...(_UTypes).
	template <typename... _Types>
	struct _TupleConstraints<false, _Types...>
	{
		template <typename... _UTypes>
		static constexpr bool __is_implicitly_constructible()
		{
			return false;
		}

		template <typename... _UTypes>
		static constexpr bool __is_explicitly_constructible()
		{
			return false;
		}
	};

	/// Primary class template, tuple
	template <typename... _Elements>
	class tuple : public _Tuple_impl<0, _Elements...>
	{
		using _Inherited = _Tuple_impl<0, _Elements...>;

#if __cpp_concepts && __cpp_consteval && __cpp_conditional_explicit // >= C++20
		template <typename... _UTypes>
		static consteval bool
		__constructible()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_constructible<_Elements, _UTypes>...>;
			else
				return false;
		}

		template <typename... _UTypes>
		static consteval bool
		__nothrow_constructible()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_nothrow_constructible<_Elements, _UTypes>...>;
			else
				return false;
		}

		template <typename... _UTypes>
		static consteval bool
		__convertible()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_convertible<_UTypes, _Elements>...>;
			else
				return false;
		}

		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 3121. tuple constructor constraints for UTypes&&... overloads
		template <typename... _UTypes>
		static consteval bool
		__disambiguating_constraint()
		{
			if constexpr (sizeof...(_Elements) != sizeof...(_UTypes))
				return false;
			else if constexpr (sizeof...(_Elements) == 1)
			{
				using _U0 = typename _Nth_type<0, _UTypes...>::type;
				return !is_same_v<remove_cvref_t<_U0>, tuple>;
			}
			else if constexpr (sizeof...(_Elements) < 4)
			{
				using _U0 = typename _Nth_type<0, _UTypes...>::type;
				if constexpr (!is_same_v<remove_cvref_t<_U0>, allocator_arg_t>)
					return true;
				else
				{
					using _T0 = typename _Nth_type<0, _Elements...>::type;
					return is_same_v<remove_cvref_t<_T0>, allocator_arg_t>;
				}
			}
			return true;
		}

		// Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
		// and the single element in Types can be initialized from TUPLE,
		// or is the same type as tuple_element_t<0, TUPLE>.
		template <typename _Tuple>
		static consteval bool
		__use_other_ctor()
		{
			if constexpr (sizeof...(_Elements) != 1)
				return false;
			else if constexpr (is_same_v<remove_cvref_t<_Tuple>, tuple>)
				return true; // Should use a copy/move constructor instead.
			else
			{
				using _Tp = typename _Nth_type<0, _Elements...>::type;
				if constexpr (is_convertible_v<_Tuple, _Tp>)
					return true;
				else if constexpr (is_constructible_v<_Tp, _Tuple>)
					return true;
			}
			return false;
		}

		template <typename... _Up>
		static consteval bool
		__dangles()
		{
#if __has_builtin(__reference_constructs_from_temporary)
			return (__reference_constructs_from_temporary(_Elements, _Up &&) || ...);
#else
			return false;
#endif
		}

#if __cpp_lib_tuple_like // >= C++23
		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 4045. tuple can create dangling references from tuple-like
		template <typename _UTuple>
		static consteval bool
		__dangles_from_tuple_like()
		{
			return []<size_t... _Is>(index_sequence<_Is...>)
			{
				return __dangles<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
			}(index_sequence_for<_Elements...>{});
		}

		template <typename _UTuple>
		static consteval bool
		__constructible_from_tuple_like()
		{
			return []<size_t... _Is>(index_sequence<_Is...>)
			{
				return __constructible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
			}(index_sequence_for<_Elements...>{});
		}

		template <typename _UTuple>
		static consteval bool
		__convertible_from_tuple_like()
		{
			return []<size_t... _Is>(index_sequence<_Is...>)
			{
				return __convertible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
			}(index_sequence_for<_Elements...>{});
		}
#endif					 // C++23

	public:
		constexpr explicit(!(__is_implicitly_default_constructible_v<_Elements> && ...))
			tuple() noexcept((is_nothrow_default_constructible_v<_Elements> && ...))
			requires(is_default_constructible_v<_Elements> && ...)
			: _Inherited()
		{
		}

		constexpr explicit(!__convertible<const _Elements &...>())
			tuple(const _Elements &...__elements) noexcept(__nothrow_constructible<const _Elements &...>())
			requires(__constructible<const _Elements &...>())
			: _Inherited(__elements...)
		{
		}

		template <typename... _UTypes>
			requires(__disambiguating_constraint<_UTypes...>()) && (__constructible<_UTypes...>()) && (!__dangles<_UTypes...>())
		constexpr explicit(!__convertible<_UTypes...>())
			tuple(_UTypes &&...__u) noexcept(__nothrow_constructible<_UTypes...>())
			: _Inherited(std::forward<_UTypes>(__u)...)
		{
		}

		template <typename... _UTypes>
			requires(__disambiguating_constraint<_UTypes...>()) && (__constructible<_UTypes...>()) && (__dangles<_UTypes...>())
		tuple(_UTypes &&...) = delete;

		constexpr tuple(const tuple &) = default;

		constexpr tuple(tuple &&) = default;

		template <typename... _UTypes>
			requires(__constructible<const _UTypes &...>()) && (!__use_other_ctor<const tuple<_UTypes...> &>()) && (!__dangles<const _UTypes &...>())
		constexpr explicit(!__convertible<const _UTypes &...>())
			tuple(const tuple<_UTypes...> &__u) noexcept(__nothrow_constructible<const _UTypes &...>())
			: _Inherited(static_cast<const _Tuple_impl<0, _UTypes...> &>(__u))
		{
		}

		template <typename... _UTypes>
			requires(__constructible<const _UTypes &...>()) && (!__use_other_ctor<const tuple<_UTypes...> &>()) && (__dangles<const _UTypes &...>())
		tuple(const tuple<_UTypes...> &) = delete;

		template <typename... _UTypes>
			requires(__constructible<_UTypes...>()) && (!__use_other_ctor<tuple<_UTypes...>>()) && (!__dangles<_UTypes...>())
		constexpr explicit(!__convertible<_UTypes...>())
			tuple(tuple<_UTypes...> &&__u) noexcept(__nothrow_constructible<_UTypes...>())
			: _Inherited(static_cast<_Tuple_impl<0, _UTypes...> &&>(__u))
		{
		}

		template <typename... _UTypes>
			requires(__constructible<_UTypes...>()) && (!__use_other_ctor<tuple<_UTypes...>>()) && (__dangles<_UTypes...>())
		tuple(tuple<_UTypes...> &&) = delete;

#if __cpp_lib_ranges_zip // >= C++23
		template <typename... _UTypes>
			requires(__constructible<_UTypes &...>()) && (!__use_other_ctor<tuple<_UTypes...> &>()) && (!__dangles<_UTypes &...>())
		constexpr explicit(!__convertible<_UTypes &...>())
			tuple(tuple<_UTypes...> &__u) noexcept(__nothrow_constructible<_UTypes &...>())
			: _Inherited(static_cast<_Tuple_impl<0, _UTypes...> &>(__u))
		{
		}

		template <typename... _UTypes>
			requires(__constructible<_UTypes &...>()) && (!__use_other_ctor<tuple<_UTypes...> &>()) && (__dangles<_UTypes &...>())
		tuple(tuple<_UTypes...> &) = delete;

		template <typename... _UTypes>
			requires(__constructible<const _UTypes...>()) && (!__use_other_ctor<const tuple<_UTypes...>>()) && (!__dangles<const _UTypes...>())
		constexpr explicit(!__convertible<const _UTypes...>())
			tuple(const tuple<_UTypes...> &&__u) noexcept(__nothrow_constructible<const _UTypes...>())
			: _Inherited(static_cast<const _Tuple_impl<0, _UTypes...> &&>(__u))
		{
		}

		template <typename... _UTypes>
			requires(__constructible<const _UTypes...>()) && (!__use_other_ctor<const tuple<_UTypes...>>()) && (__dangles<const _UTypes...>())
		tuple(const tuple<_UTypes...> &&) = delete;
#endif					 // C++23

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1 &, const _U2 &>()) && (!__dangles<const _U1 &, const _U2 &>())
		constexpr explicit(!__convertible<const _U1 &, const _U2 &>())
			tuple(const pair<_U1, _U2> &__u) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(__u.first, __u.second)
		{
		}

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1 &, const _U2 &>()) && (__dangles<const _U1 &, const _U2 &>())
		tuple(const pair<_U1, _U2> &) = delete;

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1, _U2>()) && (!__dangles<_U1, _U2>())
		constexpr explicit(!__convertible<_U1, _U2>())
			tuple(pair<_U1, _U2> &&__u) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(std::forward<_U1>(__u.first),
						 std::forward<_U2>(__u.second))
		{
		}

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1, _U2>()) && (__dangles<_U1, _U2>())
		tuple(pair<_U1, _U2> &&) = delete;

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1 &, _U2 &>()) && (!__dangles<_U1 &, _U2 &>())
		constexpr explicit(!__convertible<_U1 &, _U2 &>())
			tuple(pair<_U1, _U2> &__u) noexcept(__nothrow_constructible<_U1 &, _U2 &>())
			: _Inherited(__u.first, __u.second)
		{
		}

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1 &, _U2 &>()) && (__dangles<_U1 &, _U2 &>())
		tuple(pair<_U1, _U2> &) = delete;

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1, const _U2>()) && (!__dangles<const _U1, const _U2>())
		constexpr explicit(!__convertible<const _U1, const _U2>())
			tuple(const pair<_U1, _U2> &&__u) noexcept(__nothrow_constructible<const _U1, const _U2>())
			: _Inherited(std::forward<const _U1>(__u.first),
						 std::forward<const _U2>(__u.second))
		{
		}

		template <typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1, const _U2>()) && (__dangles<const _U1, const _U2>())
		tuple(const pair<_U1, _U2> &&) = delete;
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <__eligible_tuple_like<tuple> _UTuple>
			requires(__constructible_from_tuple_like<_UTuple>()) && (!__use_other_ctor<_UTuple>()) && (!__dangles_from_tuple_like<_UTuple>())
		constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
			tuple(_UTuple &&__u)
			: _Inherited(__tuple_like_tag_t{},
						 std::forward<_UTuple>(__u),
						 index_sequence_for<_Elements...>{})
		{
		}

		template <__eligible_tuple_like<tuple> _UTuple>
			requires(__constructible_from_tuple_like<_UTuple>()) && (!__use_other_ctor<_UTuple>()) && (__dangles_from_tuple_like<_UTuple>())
		tuple(_UTuple &&) = delete;
#endif					 // C++23

		// Allocator-extended constructors.

		template <typename _Alloc>
		constexpr explicit(!(__is_implicitly_default_constructible_v<_Elements> && ...))
			tuple(allocator_arg_t __tag, const _Alloc &__a)
			requires(is_default_constructible_v<_Elements> && ...)
			: _Inherited(__tag, __a)
		{
		}

		template <typename _Alloc>
		constexpr explicit(!__convertible<const _Elements &...>())
			tuple(allocator_arg_t __tag, const _Alloc &__a,
				  const _Elements &...__elements)
			requires(__constructible<const _Elements &...>())
			: _Inherited(__tag, __a, __elements...)
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__disambiguating_constraint<_UTypes...>()) && (__constructible<_UTypes...>()) && (!__dangles<_UTypes...>())
		constexpr explicit(!__convertible<_UTypes...>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, _UTypes &&...__u)
			: _Inherited(__tag, __a, std::forward<_UTypes>(__u)...)
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__disambiguating_constraint<_UTypes...>()) && (__constructible<_UTypes...>()) && (__dangles<_UTypes...>())
		tuple(allocator_arg_t, const _Alloc &, _UTypes &&...) = delete;

		template <typename _Alloc>
		constexpr tuple(allocator_arg_t __tag, const _Alloc &__a, const tuple &__u)
			: _Inherited(__tag, __a, static_cast<const _Inherited &>(__u))
		{
		}

		template <typename _Alloc>
			requires(__constructible<_Elements...>())
		constexpr tuple(allocator_arg_t __tag, const _Alloc &__a, tuple &&__u)
			: _Inherited(__tag, __a, static_cast<_Inherited &&>(__u))
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<const _UTypes &...>()) && (!__use_other_ctor<const tuple<_UTypes...> &>()) && (!__dangles<const _UTypes &...>())
		constexpr explicit(!__convertible<const _UTypes &...>())
			tuple(allocator_arg_t __tag, const _Alloc &__a,
				  const tuple<_UTypes...> &__u)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _UTypes...> &>(__u))
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<const _UTypes &...>()) && (!__use_other_ctor<const tuple<_UTypes...> &>()) && (__dangles<const _UTypes &...>())
		tuple(allocator_arg_t, const _Alloc &, const tuple<_UTypes...> &) = delete;

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<_UTypes...>()) && (!__use_other_ctor<tuple<_UTypes...>>()) && (!__dangles<_UTypes...>())
		constexpr explicit(!__use_other_ctor<tuple<_UTypes...>>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, tuple<_UTypes...> &&__u)
			: _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _UTypes...> &&>(__u))
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<_UTypes...>()) && (!__use_other_ctor<tuple<_UTypes...>>()) && (__dangles<_UTypes...>())
		tuple(allocator_arg_t, const _Alloc &, tuple<_UTypes...> &&) = delete;

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<_UTypes &...>()) && (!__use_other_ctor<tuple<_UTypes...> &>()) && (!__dangles<_UTypes &...>())
		constexpr explicit(!__convertible<_UTypes &...>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, tuple<_UTypes...> &__u)
			: _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _UTypes...> &>(__u))
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<_UTypes &...>()) && (!__use_other_ctor<tuple<_UTypes...> &>()) && (__dangles<_UTypes &...>())
		tuple(allocator_arg_t, const _Alloc &, tuple<_UTypes...> &) = delete;

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<const _UTypes...>()) && (!__use_other_ctor<const tuple<_UTypes...>>()) && (!__dangles<const _UTypes...>())
		constexpr explicit(!__convertible<const _UTypes...>())
			tuple(allocator_arg_t __tag, const _Alloc &__a,
				  const tuple<_UTypes...> &&__u)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _UTypes...> &&>(__u))
		{
		}

		template <typename _Alloc, typename... _UTypes>
			requires(__constructible<const _UTypes...>()) && (!__use_other_ctor<const tuple<_UTypes...>>()) && (__dangles<const _UTypes...>())
		tuple(allocator_arg_t, const _Alloc &, const tuple<_UTypes...> &&) = delete;
#endif					 // C++23

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1 &, const _U2 &>()) && (!__dangles<const _U1 &, const _U2 &>())
		constexpr explicit(!__convertible<const _U1 &, const _U2 &>())
			tuple(allocator_arg_t __tag, const _Alloc &__a,
				  const pair<_U1, _U2> &__u) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(__tag, __a, __u.first, __u.second)
		{
		}

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1 &, const _U2 &>()) && (__dangles<const _U1 &, const _U2 &>())
		tuple(allocator_arg_t, const _Alloc &, const pair<_U1, _U2> &) = delete;

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1, _U2>()) && (!__dangles<_U1, _U2>())
		constexpr explicit(!__convertible<_U1, _U2>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, pair<_U1, _U2> &&__u) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(__tag, __a, std::move(__u.first), std::move(__u.second))
		{
		}

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1, _U2>()) && (__dangles<_U1, _U2>())
		tuple(allocator_arg_t, const _Alloc &, pair<_U1, _U2> &&) = delete;

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1 &, _U2 &>()) && (!__dangles<_U1 &, _U2 &>())
		constexpr explicit(!__convertible<_U1 &, _U2 &>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, pair<_U1, _U2> &__u) noexcept(__nothrow_constructible<_U1 &, _U2 &>())
			: _Inherited(__tag, __a, __u.first, __u.second)
		{
		}

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<_U1 &, _U2 &>()) && (__dangles<_U1 &, _U2 &>())
		tuple(allocator_arg_t, const _Alloc &, pair<_U1, _U2> &) = delete;

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1, const _U2>()) && (!__dangles<const _U1, const _U2>())
		constexpr explicit(!__convertible<const _U1, const _U2>())
			tuple(allocator_arg_t __tag, const _Alloc &__a,
				  const pair<_U1, _U2> &&__u) noexcept(__nothrow_constructible<const _U1, const _U2>())
			: _Inherited(__tag, __a, std::move(__u.first), std::move(__u.second))
		{
		}

		template <typename _Alloc, typename _U1, typename _U2>
			requires(sizeof...(_Elements) == 2) && (__constructible<const _U1, const _U2>()) && (__dangles<const _U1, const _U2>())
		tuple(allocator_arg_t, const _Alloc &, const pair<_U1, _U2> &&) = delete;
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
			requires(__constructible_from_tuple_like<_UTuple>()) && (!__use_other_ctor<_UTuple>()) && (!__dangles_from_tuple_like<_UTuple>())
		constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
			tuple(allocator_arg_t __tag, const _Alloc &__a, _UTuple &&__u)
			: _Inherited(__tuple_like_tag_t{},
						 __tag, __a, std::forward<_UTuple>(__u),
						 index_sequence_for<_Elements...>{})
		{
		}

		template <typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
			requires(__constructible_from_tuple_like<_UTuple>()) && (!__use_other_ctor<_UTuple>()) && (__dangles_from_tuple_like<_UTuple>())
		tuple(allocator_arg_t, const _Alloc &, _UTuple &&) = delete;
#endif					 // C++23

#else // !(concepts && conditional_explicit)

		template <bool _Cond>
		using _TCC = _TupleConstraints<_Cond, _Elements...>;

		// Constraint for non-explicit default constructor
		template <bool _Dummy>
		using _ImplicitDefaultCtor = __enable_if_t<
			_TCC<_Dummy>::__is_implicitly_default_constructible(),
			bool>;

		// Constraint for explicit default constructor
		template <bool _Dummy>
		using _ExplicitDefaultCtor = __enable_if_t<
			_TCC<_Dummy>::__is_explicitly_default_constructible(),
			bool>;

		// Constraint for non-explicit constructors
		template <bool _Cond, typename... _Args>
		using _ImplicitCtor = __enable_if_t<
			_TCC<_Cond>::template __is_implicitly_constructible<_Args...>(),
			bool>;

		// Constraint for non-explicit constructors
		template <bool _Cond, typename... _Args>
		using _ExplicitCtor = __enable_if_t<
			_TCC<_Cond>::template __is_explicitly_constructible<_Args...>(),
			bool>;

		// Condition for noexcept-specifier of a constructor.
		template <typename... _UElements>
		static constexpr bool __nothrow_constructible()
		{
			return __and_<is_nothrow_constructible<_Elements, _UElements>...>::value;
		}

		// Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) == 1.
		template <typename _Up>
		static constexpr bool __valid_args()
		{
			return sizeof...(_Elements) == 1 && !is_same<tuple, __remove_cvref_t<_Up>>::value;
		}

		// Constraint for tuple(_UTypes&&...) where sizeof...(_UTypes) > 1.
		template <typename, typename, typename... _Tail>
		static constexpr bool __valid_args()
		{
			return (sizeof...(_Tail) + 2) == sizeof...(_Elements);
		}

		/* Constraint for constructors with a tuple<UTypes...> parameter ensures
		 * that the constructor is only viable when it would not interfere with
		 * tuple(UTypes&&...) or tuple(const tuple&) or tuple(tuple&&).
		 * Such constructors are only viable if:
		 * either sizeof...(Types) != 1,
		 * or (when Types... expands to T and UTypes... expands to U)
		 * is_convertible_v<TUPLE, T>, is_constructible_v<T, TUPLE>,
		 * and is_same_v<T, U> are all false.
		 */
		template <typename _Tuple, typename = tuple,
				  typename = __remove_cvref_t<_Tuple>>
		struct _UseOtherCtor
			: false_type
		{
		};
		// If TUPLE is convertible to the single element in *this,
		// then TUPLE should match tuple(UTypes&&...) instead.
		template <typename _Tuple, typename _Tp, typename _Up>
		struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Up>>
			: __or_<is_convertible<_Tuple, _Tp>, is_constructible<_Tp, _Tuple>>::type
		{
		};
		// If TUPLE and *this each have a single element of the same type,
		// then TUPLE should match a copy/move constructor instead.
		template <typename _Tuple, typename _Tp>
		struct _UseOtherCtor<_Tuple, tuple<_Tp>, tuple<_Tp>>
			: true_type
		{
		};

		// Return true iff sizeof...(Types) == 1 && tuple_size_v<TUPLE> == 1
		// and the single element in Types can be initialized from TUPLE,
		// or is the same type as tuple_element_t<0, TUPLE>.
		template <typename _Tuple>
		static constexpr bool __use_other_ctor()
		{
			return _UseOtherCtor<_Tuple>::value;
		}

		/// @cond undocumented
#undef __glibcxx_no_dangling_refs
#if __has_builtin(__reference_constructs_from_temporary) && defined _GLIBCXX_DEBUG
		// Error if construction from U... would create a dangling ref.
#if __cpp_fold_expressions
#define __glibcxx_dangling_refs(U) \
	(__reference_constructs_from_temporary(_Elements, U) || ...)
#else
#define __glibcxx_dangling_refs(U) \
	__or_<__bool_constant<__reference_constructs_from_temporary(_Elements, U)>...>::value
#endif
#define __glibcxx_no_dangling_refs(U)          \
	static_assert(!__glibcxx_dangling_refs(U), \
				  "std::tuple constructor creates a dangling reference")
#else
#define __glibcxx_no_dangling_refs(U)
#endif
		/// @endcond

	public:
		template <typename _Dummy = void,
				  _ImplicitDefaultCtor<is_void<_Dummy>::value> = true>
		constexpr tuple() noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
			: _Inherited() {}

		template <typename _Dummy = void,
				  _ExplicitDefaultCtor<is_void<_Dummy>::value> = false>
		explicit constexpr tuple() noexcept(__and_<is_nothrow_default_constructible<_Elements>...>::value)
			: _Inherited() {}

		template <bool _NotEmpty = (sizeof...(_Elements) >= 1),
				  _ImplicitCtor<_NotEmpty, const _Elements &...> = true>
		constexpr tuple(const _Elements &...__elements) noexcept(__nothrow_constructible<const _Elements &...>())
			: _Inherited(__elements...) {}

		template <bool _NotEmpty = (sizeof...(_Elements) >= 1),
				  _ExplicitCtor<_NotEmpty, const _Elements &...> = false>
		explicit constexpr tuple(const _Elements &...__elements) noexcept(__nothrow_constructible<const _Elements &...>())
			: _Inherited(__elements...) {}

		template <typename... _UElements,
				  bool _Valid = __valid_args<_UElements...>(),
				  _ImplicitCtor<_Valid, _UElements...> = true>
		constexpr tuple(_UElements &&...__elements) noexcept(__nothrow_constructible<_UElements...>())
			: _Inherited(std::forward<_UElements>(__elements)...)
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		template <typename... _UElements,
				  bool _Valid = __valid_args<_UElements...>(),
				  _ExplicitCtor<_Valid, _UElements...> = false>
		explicit constexpr tuple(_UElements &&...__elements) noexcept(__nothrow_constructible<_UElements...>())
			: _Inherited(std::forward<_UElements>(__elements)...)
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		constexpr tuple(const tuple &) = default;

		constexpr tuple(tuple &&) = default;

		template <typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<const tuple<_UElements...> &>(),
				  _ImplicitCtor<_Valid, const _UElements &...> = true>
		constexpr tuple(const tuple<_UElements...> &__in) noexcept(__nothrow_constructible<const _UElements &...>())
			: _Inherited(static_cast<const _Tuple_impl<0, _UElements...> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _UElements &);
		}

		template <typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<const tuple<_UElements...> &>(),
				  _ExplicitCtor<_Valid, const _UElements &...> = false>
		explicit constexpr tuple(const tuple<_UElements...> &__in) noexcept(__nothrow_constructible<const _UElements &...>())
			: _Inherited(static_cast<const _Tuple_impl<0, _UElements...> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _UElements &);
		}

		template <typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<tuple<_UElements...> &&>(),
				  _ImplicitCtor<_Valid, _UElements...> = true>
		constexpr tuple(tuple<_UElements...> &&__in) noexcept(__nothrow_constructible<_UElements...>())
			: _Inherited(static_cast<_Tuple_impl<0, _UElements...> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		template <typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<tuple<_UElements...> &&>(),
				  _ExplicitCtor<_Valid, _UElements...> = false>
		explicit constexpr tuple(tuple<_UElements...> &&__in) noexcept(__nothrow_constructible<_UElements...>())
			: _Inherited(static_cast<_Tuple_impl<0, _UElements...> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		// Allocator-extended constructors.

		template <typename _Alloc,
				  _ImplicitDefaultCtor<is_object<_Alloc>::value> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a)
			: _Inherited(__tag, __a) {}

		template <typename _Alloc,
				  _ExplicitDefaultCtor<is_object<_Alloc>::value> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a)
			: _Inherited(__tag, __a) {}

		template <typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
				  _ImplicitCtor<_NotEmpty, const _Elements &...> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const _Elements &...__elements)
			: _Inherited(__tag, __a, __elements...) {}

		template <typename _Alloc, bool _NotEmpty = (sizeof...(_Elements) >= 1),
				  _ExplicitCtor<_NotEmpty, const _Elements &...> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a,
											const _Elements &...__elements)
			: _Inherited(__tag, __a, __elements...) {}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = __valid_args<_UElements...>(),
				  _ImplicitCtor<_Valid, _UElements...> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  _UElements &&...__elements)
			: _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = __valid_args<_UElements...>(),
				  _ExplicitCtor<_Valid, _UElements...> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a,
											_UElements &&...__elements)
			: _Inherited(__tag, __a, std::forward<_UElements>(__elements)...)
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, const tuple &__in)
			: _Inherited(__tag, __a, static_cast<const _Inherited &>(__in)) {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, tuple &&__in)
			: _Inherited(__tag, __a, static_cast<_Inherited &&>(__in)) {}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<const tuple<_UElements...> &>(),
				  _ImplicitCtor<_Valid, const _UElements &...> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const tuple<_UElements...> &__in)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _UElements...> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _UElements &);
		}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<const tuple<_UElements...> &>(),
				  _ExplicitCtor<_Valid, const _UElements &...> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a,
											const tuple<_UElements...> &__in)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _UElements...> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _UElements &);
		}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<tuple<_UElements...> &&>(),
				  _ImplicitCtor<_Valid, _UElements...> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  tuple<_UElements...> &&__in)
			: _Inherited(__tag, __a,
						 static_cast<_Tuple_impl<0, _UElements...> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}

		template <typename _Alloc, typename... _UElements,
				  bool _Valid = (sizeof...(_Elements) == sizeof...(_UElements)) && !__use_other_ctor<tuple<_UElements...> &&>(),
				  _ExplicitCtor<_Valid, _UElements...> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a,
											tuple<_UElements...> &&__in)
			: _Inherited(__tag, __a,
						 static_cast<_Tuple_impl<0, _UElements...> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_UElements &&);
		}
#endif // concepts && conditional_explicit

		// tuple assignment

#if __cpp_concepts && __cpp_consteval // >= C++20
	private:
		template <typename... _UTypes>
		static consteval bool
		__assignable()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_assignable<_Elements &, _UTypes>...>;
			else
				return false;
		}

		template <typename... _UTypes>
		static consteval bool
		__nothrow_assignable()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_nothrow_assignable<_Elements &, _UTypes>...>;
			else
				return false;
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename... _UTypes>
		static consteval bool
		__const_assignable()
		{
			if constexpr (sizeof...(_UTypes) == sizeof...(_Elements))
				return __and_v<is_assignable<const _Elements &, _UTypes>...>;
			else
				return false;
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <typename _UTuple>
		static consteval bool
		__assignable_from_tuple_like()
		{
			return []<size_t... _Is>(index_sequence<_Is...>)
			{
				return __assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
			}(index_sequence_for<_Elements...>{});
		}

		template <typename _UTuple>
		static consteval bool
		__const_assignable_from_tuple_like()
		{
			return []<size_t... _Is>(index_sequence<_Is...>)
			{
				return __const_assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
			}(index_sequence_for<_Elements...>{});
		}
#endif					 // C++23

	public:
		tuple &operator=(const tuple &__u) = delete;

		constexpr tuple &
		operator=(const tuple &__u) noexcept(__nothrow_assignable<const _Elements &...>())
			requires(__assignable<const _Elements &...>())
		{
			this->_M_assign(__u);
			return *this;
		}

		constexpr tuple &
		operator=(tuple &&__u) noexcept(__nothrow_assignable<_Elements...>())
			requires(__assignable<_Elements...>())
		{
			this->_M_assign(std::move(__u));
			return *this;
		}

		template <typename... _UTypes>
			requires(__assignable<const _UTypes &...>())
		constexpr tuple &
		operator=(const tuple<_UTypes...> &__u) noexcept(__nothrow_assignable<const _UTypes &...>())
		{
			this->_M_assign(__u);
			return *this;
		}

		template <typename... _UTypes>
			requires(__assignable<_UTypes...>())
		constexpr tuple &
		operator=(tuple<_UTypes...> &&__u) noexcept(__nothrow_assignable<_UTypes...>())
		{
			this->_M_assign(std::move(__u));
			return *this;
		}

#if __cpp_lib_ranges_zip // >= C++23
		constexpr const tuple &
		operator=(const tuple &__u) const
			requires(__const_assignable<const _Elements &...>())
		{
			this->_M_assign(__u);
			return *this;
		}

		constexpr const tuple &
		operator=(tuple &&__u) const
			requires(__const_assignable<_Elements...>())
		{
			this->_M_assign(std::move(__u));
			return *this;
		}

		template <typename... _UTypes>
		constexpr const tuple &
		operator=(const tuple<_UTypes...> &__u) const
			requires(__const_assignable<const _UTypes &...>())
		{
			this->_M_assign(__u);
			return *this;
		}

		template <typename... _UTypes>
		constexpr const tuple &
		operator=(tuple<_UTypes...> &&__u) const
			requires(__const_assignable<_UTypes...>())
		{
			this->_M_assign(std::move(__u));
			return *this;
		}
#endif					 // C++23

		template <typename _U1, typename _U2>
			requires(__assignable<const _U1 &, const _U2 &>())
		constexpr tuple &
		operator=(const pair<_U1, _U2> &__u) noexcept(__nothrow_assignable<const _U1 &, const _U2 &>())
		{
			this->_M_head(*this) = __u.first;
			this->_M_tail(*this)._M_head(*this) = __u.second;
			return *this;
		}

		template <typename _U1, typename _U2>
			requires(__assignable<_U1, _U2>())
		constexpr tuple &
		operator=(pair<_U1, _U2> &&__u) noexcept(__nothrow_assignable<_U1, _U2>())
		{
			this->_M_head(*this) = std::forward<_U1>(__u.first);
			this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__u.second);
			return *this;
		}

#if __cpp_lib_ranges_zip // >= C++23
		template <typename _U1, typename _U2>
			requires(__const_assignable<const _U1 &, const _U2>())
		constexpr const tuple &
		operator=(const pair<_U1, _U2> &__u) const
		{
			this->_M_head(*this) = __u.first;
			this->_M_tail(*this)._M_head(*this) = __u.second;
			return *this;
		}

		template <typename _U1, typename _U2>
			requires(__const_assignable<_U1, _U2>())
		constexpr const tuple &
		operator=(pair<_U1, _U2> &&__u) const
		{
			this->_M_head(*this) = std::forward<_U1>(__u.first);
			this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__u.second);
			return *this;
		}
#endif					 // C++23

#if __cpp_lib_tuple_like // >= C++23
		template <__eligible_tuple_like<tuple> _UTuple>
			requires(__assignable_from_tuple_like<_UTuple>())
		constexpr tuple &
		operator=(_UTuple &&__u)
		{
			this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
			return *this;
		}

		template <__eligible_tuple_like<tuple> _UTuple>
			requires(__const_assignable_from_tuple_like<_UTuple>())
		constexpr const tuple &
		operator=(_UTuple &&__u) const
		{
			this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
			return *this;
		}

		template <__tuple_like _UTuple>
			requires(!__is_tuple_v<_UTuple>)
		friend constexpr bool
		operator== [[nodiscard]] (const tuple &__t, const _UTuple &__u)
		{
			static_assert(sizeof...(_Elements) == tuple_size_v<_UTuple>,
						  "tuple objects can only be compared if they have equal sizes.");
			return [&]<size_t... _Is>(index_sequence<_Is...>)
			{
				return (bool(std::get<_Is>(__t) == std::get<_Is>(__u)) && ...);
			}(index_sequence_for<_Elements...>{});
		}

		template <__tuple_like _UTuple,
				  typename = make_index_sequence<tuple_size_v<_UTuple>>>
		struct __tuple_like_common_comparison_category;

		template <__tuple_like _UTuple, size_t... _Is>
			requires requires { typename void_t<__detail::__synth3way_t<_Elements, tuple_element_t<_Is, _UTuple>>...>; }
		struct __tuple_like_common_comparison_category<_UTuple, index_sequence<_Is...>>
		{
			using type = common_comparison_category_t<__detail::__synth3way_t<_Elements, tuple_element_t<_Is, _UTuple>>...>;
		};

		template <__tuple_like _UTuple>
			requires(!__is_tuple_v<_UTuple>)
		friend constexpr typename __tuple_like_common_comparison_category<_UTuple>::type
		operator<=>(const tuple &__t, const _UTuple &__u)
		{
			using _Cat = typename __tuple_like_common_comparison_category<_UTuple>::type;
			return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Elements...>());
		}
#endif					 // C++23

#else  // ! (concepts && consteval)

	private:
		template <typename... _UElements>
		static constexpr __enable_if_t<sizeof...(_UElements) == sizeof...(_Elements), bool>
		__assignable()
		{
			return __and_<is_assignable<_Elements &, _UElements>...>::value;
		}

		// Condition for noexcept-specifier of an assignment operator.
		template <typename... _UElements>
		static constexpr bool __nothrow_assignable()
		{
			return __and_<is_nothrow_assignable<_Elements &, _UElements>...>::value;
		}

	public:
		template <typename... _UElements>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<const _UElements &...>(), tuple &>
			operator=(const tuple<_UElements...> &__in) noexcept(__nothrow_assignable<const _UElements &...>())
		{
			this->_M_assign(__in);
			return *this;
		}

		template <typename... _UElements>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<_UElements...>(), tuple &>
			operator=(tuple<_UElements...> &&__in) noexcept(__nothrow_assignable<_UElements...>())
		{
			this->_M_assign(std::move(__in));
			return *this;
		}
#endif // concepts && consteval

		// tuple swap
		_GLIBCXX20_CONSTEXPR
		void
		swap(tuple &__in) noexcept(__and_<__is_nothrow_swappable<_Elements>...>::value)
		{
			_Inherited::_M_swap(__in);
		}

#if __cpp_lib_ranges_zip // >= C++23
		// As an extension, we constrain the const swap member function in order
		// to continue accepting explicit instantiation of tuples whose elements
		// are not all const swappable.  Without this constraint, such an
		// explicit instantiation would also instantiate the ill-formed body of
		// this function and yield a hard error.  This constraint shouldn't
		// affect the behavior of valid programs.
		constexpr void
		swap(const tuple &__in) const
			noexcept(__and_v<__is_nothrow_swappable<const _Elements>...>)
			requires(is_swappable_v<const _Elements> && ...)
		{
			_Inherited::_M_swap(__in);
		}
#endif					 // C++23
	};

#if __cpp_deduction_guides >= 201606
	template <typename... _UTypes>
	tuple(_UTypes...) -> tuple<_UTypes...>;
	template <typename _T1, typename _T2>
	tuple(pair<_T1, _T2>) -> tuple<_T1, _T2>;
	template <typename _Alloc, typename... _UTypes>
	tuple(allocator_arg_t, _Alloc, _UTypes...) -> tuple<_UTypes...>;
	template <typename _Alloc, typename _T1, typename _T2>
	tuple(allocator_arg_t, _Alloc, pair<_T1, _T2>) -> tuple<_T1, _T2>;
	template <typename _Alloc, typename... _UTypes>
	tuple(allocator_arg_t, _Alloc, tuple<_UTypes...>) -> tuple<_UTypes...>;
#endif

	// Explicit specialization, zero-element tuple.
	template <>
	class tuple<>
	{
	public:
		_GLIBCXX20_CONSTEXPR
		void swap(tuple &) noexcept { /* no-op */ }
#if __cpp_lib_ranges_zip // >= C++23
		constexpr void swap(const tuple &) const noexcept { /* no-op */ }
#endif
		// We need the default since we're going to define no-op
		// allocator constructors.
		tuple() = default;
		// No-op allocator constructors.
		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t, const _Alloc &) noexcept {}
		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t, const _Alloc &, const tuple &) noexcept {}
	};

#if !(__cpp_concepts && __cpp_consteval && __cpp_conditional_explicit) // !C++20
	/// Partial specialization, 2-element tuple.
	/// Includes construction and assignment from a pair.
	template <typename _T1, typename _T2>
	class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
	{
		typedef _Tuple_impl<0, _T1, _T2> _Inherited;

		// Constraint for non-explicit default constructor
		template <bool _Dummy, typename _U1, typename _U2>
		using _ImplicitDefaultCtor = __enable_if_t<
			_TupleConstraints<_Dummy, _U1, _U2>::
				__is_implicitly_default_constructible(),
			bool>;

		// Constraint for explicit default constructor
		template <bool _Dummy, typename _U1, typename _U2>
		using _ExplicitDefaultCtor = __enable_if_t<
			_TupleConstraints<_Dummy, _U1, _U2>::
				__is_explicitly_default_constructible(),
			bool>;

		template <bool _Dummy>
		using _TCC = _TupleConstraints<_Dummy, _T1, _T2>;

		// Constraint for non-explicit constructors
		template <bool _Cond, typename _U1, typename _U2>
		using _ImplicitCtor = __enable_if_t<
			_TCC<_Cond>::template __is_implicitly_constructible<_U1, _U2>(),
			bool>;

		// Constraint for non-explicit constructors
		template <bool _Cond, typename _U1, typename _U2>
		using _ExplicitCtor = __enable_if_t<
			_TCC<_Cond>::template __is_explicitly_constructible<_U1, _U2>(),
			bool>;

		template <typename _U1, typename _U2>
		static constexpr bool __assignable()
		{
			return __and_<is_assignable<_T1 &, _U1>,
						  is_assignable<_T2 &, _U2>>::value;
		}

		template <typename _U1, typename _U2>
		static constexpr bool __nothrow_assignable()
		{
			return __and_<is_nothrow_assignable<_T1 &, _U1>,
						  is_nothrow_assignable<_T2 &, _U2>>::value;
		}

		template <typename _U1, typename _U2>
		static constexpr bool __nothrow_constructible()
		{
			return __and_<is_nothrow_constructible<_T1, _U1>,
						  is_nothrow_constructible<_T2, _U2>>::value;
		}

		static constexpr bool __nothrow_default_constructible()
		{
			return __and_<is_nothrow_default_constructible<_T1>,
						  is_nothrow_default_constructible<_T2>>::value;
		}

		template <typename _U1>
		static constexpr bool __is_alloc_arg()
		{
			return is_same<__remove_cvref_t<_U1>, allocator_arg_t>::value;
		}

		/// @cond undocumented
#undef __glibcxx_no_dangling_refs
		// Error if construction from _U1 and _U2 would create a dangling ref.
#if __has_builtin(__reference_constructs_from_temporary) && defined _GLIBCXX_DEBUG
#define __glibcxx_no_dangling_refs(_U1, _U2)                                                                            \
	static_assert(!__reference_constructs_from_temporary(_T1, _U1) && !__reference_constructs_from_temporary(_T2, _U2), \
				  "std::tuple constructor creates a dangling reference")
#else
#define __glibcxx_no_dangling_refs(_U1, _U2)
#endif
		/// @endcond

	public:
		template <bool _Dummy = true,
				  _ImplicitDefaultCtor<_Dummy, _T1, _T2> = true>
		constexpr tuple() noexcept(__nothrow_default_constructible())
			: _Inherited() {}

		template <bool _Dummy = true,
				  _ExplicitDefaultCtor<_Dummy, _T1, _T2> = false>
		explicit constexpr tuple() noexcept(__nothrow_default_constructible())
			: _Inherited() {}

		template <bool _Dummy = true,
				  _ImplicitCtor<_Dummy, const _T1 &, const _T2 &> = true>
		constexpr tuple(const _T1 &__a1, const _T2 &__a2) noexcept(__nothrow_constructible<const _T1 &, const _T2 &>())
			: _Inherited(__a1, __a2) {}

		template <bool _Dummy = true,
				  _ExplicitCtor<_Dummy, const _T1 &, const _T2 &> = false>
		explicit constexpr tuple(const _T1 &__a1, const _T2 &__a2) noexcept(__nothrow_constructible<const _T1 &, const _T2 &>())
			: _Inherited(__a1, __a2) {}

		template <typename _U1, typename _U2,
				  _ImplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = true>
		constexpr tuple(_U1 &&__a1, _U2 &&__a2) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _U1, typename _U2,
				  _ExplicitCtor<!__is_alloc_arg<_U1>(), _U1, _U2> = false>
		explicit constexpr tuple(_U1 &&__a1, _U2 &&__a2) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		constexpr tuple(const tuple &) = default;

		constexpr tuple(tuple &&) = default;

		template <typename _U1, typename _U2,
				  _ImplicitCtor<true, const _U1 &, const _U2 &> = true>
		constexpr tuple(const tuple<_U1, _U2> &__in) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _U1, typename _U2,
				  _ExplicitCtor<true, const _U1 &, const _U2 &> = false>
		explicit constexpr tuple(const tuple<_U1, _U2> &__in) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _U1, typename _U2,
				  _ImplicitCtor<true, _U1, _U2> = true>
		constexpr tuple(tuple<_U1, _U2> &&__in) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(static_cast<_Tuple_impl<0, _U1, _U2> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _U1, typename _U2,
				  _ExplicitCtor<true, _U1, _U2> = false>
		explicit constexpr tuple(tuple<_U1, _U2> &&__in) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(static_cast<_Tuple_impl<0, _U1, _U2> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _U1, typename _U2,
				  _ImplicitCtor<true, const _U1 &, const _U2 &> = true>
		constexpr tuple(const pair<_U1, _U2> &__in) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(__in.first, __in.second)
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _U1, typename _U2,
				  _ExplicitCtor<true, const _U1 &, const _U2 &> = false>
		explicit constexpr tuple(const pair<_U1, _U2> &__in) noexcept(__nothrow_constructible<const _U1 &, const _U2 &>())
			: _Inherited(__in.first, __in.second)
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _U1, typename _U2,
				  _ImplicitCtor<true, _U1, _U2> = true>
		constexpr tuple(pair<_U1, _U2> &&__in) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(std::forward<_U1>(__in.first),
						 std::forward<_U2>(__in.second))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _U1, typename _U2,
				  _ExplicitCtor<true, _U1, _U2> = false>
		explicit constexpr tuple(pair<_U1, _U2> &&__in) noexcept(__nothrow_constructible<_U1, _U2>())
			: _Inherited(std::forward<_U1>(__in.first),
						 std::forward<_U2>(__in.second))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		// Allocator-extended constructors.

		template <typename _Alloc,
				  _ImplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a)
			: _Inherited(__tag, __a) {}

		template <typename _Alloc,
				  _ExplicitDefaultCtor<is_object<_Alloc>::value, _T1, _T2> = false>
		_GLIBCXX20_CONSTEXPR explicit tuple(allocator_arg_t __tag, const _Alloc &__a)
			: _Inherited(__tag, __a) {}

		template <typename _Alloc, bool _Dummy = true,
				  _ImplicitCtor<_Dummy, const _T1 &, const _T2 &> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const _T1 &__a1, const _T2 &__a2)
			: _Inherited(__tag, __a, __a1, __a2) {}

		template <typename _Alloc, bool _Dummy = true,
				  _ExplicitCtor<_Dummy, const _T1 &, const _T2 &> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const _T1 &__a1, const _T2 &__a2)
			: _Inherited(__tag, __a, __a1, __a2) {}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ImplicitCtor<true, _U1, _U2> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, _U1 &&__a1, _U2 &&__a2)
			: _Inherited(__tag, __a, std::forward<_U1>(__a1),
						 std::forward<_U2>(__a2))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ExplicitCtor<true, _U1, _U2> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  _U1 &&__a1, _U2 &&__a2)
			: _Inherited(__tag, __a, std::forward<_U1>(__a1),
						 std::forward<_U2>(__a2))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, const tuple &__in)
			: _Inherited(__tag, __a, static_cast<const _Inherited &>(__in)) {}

		template <typename _Alloc>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, tuple &&__in)
			: _Inherited(__tag, __a, static_cast<_Inherited &&>(__in)) {}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ImplicitCtor<true, const _U1 &, const _U2 &> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const tuple<_U1, _U2> &__in)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _U1, _U2> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ExplicitCtor<true, const _U1 &, const _U2 &> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const tuple<_U1, _U2> &__in)
			: _Inherited(__tag, __a,
						 static_cast<const _Tuple_impl<0, _U1, _U2> &>(__in))
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ImplicitCtor<true, _U1, _U2> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, tuple<_U1, _U2> &&__in)
			: _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ExplicitCtor<true, _U1, _U2> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, tuple<_U1, _U2> &&__in)
			: _Inherited(__tag, __a, static_cast<_Tuple_impl<0, _U1, _U2> &&>(__in))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ImplicitCtor<true, const _U1 &, const _U2 &> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const pair<_U1, _U2> &__in)
			: _Inherited(__tag, __a, __in.first, __in.second)
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ExplicitCtor<true, const _U1 &, const _U2 &> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a,
			  const pair<_U1, _U2> &__in)
			: _Inherited(__tag, __a, __in.first, __in.second)
		{
			__glibcxx_no_dangling_refs(const _U1 &, const _U2 &);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ImplicitCtor<true, _U1, _U2> = true>
		_GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, pair<_U1, _U2> &&__in)
			: _Inherited(__tag, __a, std::forward<_U1>(__in.first),
						 std::forward<_U2>(__in.second))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _Alloc, typename _U1, typename _U2,
				  _ExplicitCtor<true, _U1, _U2> = false>
		explicit _GLIBCXX20_CONSTEXPR
		tuple(allocator_arg_t __tag, const _Alloc &__a, pair<_U1, _U2> &&__in)
			: _Inherited(__tag, __a, std::forward<_U1>(__in.first),
						 std::forward<_U2>(__in.second))
		{
			__glibcxx_no_dangling_refs(_U1 &&, _U2 &&);
		}

		template <typename _U1, typename _U2>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<const _U1 &, const _U2 &>(), tuple &>
			operator=(const tuple<_U1, _U2> &__in) noexcept(__nothrow_assignable<const _U1 &, const _U2 &>())
		{
			this->_M_assign(__in);
			return *this;
		}

		template <typename _U1, typename _U2>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<_U1, _U2>(), tuple &>
			operator=(tuple<_U1, _U2> &&__in) noexcept(__nothrow_assignable<_U1, _U2>())
		{
			this->_M_assign(std::move(__in));
			return *this;
		}

		template <typename _U1, typename _U2>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<const _U1 &, const _U2 &>(), tuple &>
			operator=(const pair<_U1, _U2> &__in) noexcept(__nothrow_assignable<const _U1 &, const _U2 &>())
		{
			this->_M_head(*this) = __in.first;
			this->_M_tail(*this)._M_head(*this) = __in.second;
			return *this;
		}

		template <typename _U1, typename _U2>
		_GLIBCXX20_CONSTEXPR
			__enable_if_t<__assignable<_U1, _U2>(), tuple &>
			operator=(pair<_U1, _U2> &&__in) noexcept(__nothrow_assignable<_U1, _U2>())
		{
			this->_M_head(*this) = std::forward<_U1>(__in.first);
			this->_M_tail(*this)._M_head(*this) = std::forward<_U2>(__in.second);
			return *this;
		}

		_GLIBCXX20_CONSTEXPR
		void
		swap(tuple &__in) noexcept(__and_<__is_nothrow_swappable<_T1>,
										  __is_nothrow_swappable<_T2>>::value)
		{
			_Inherited::_M_swap(__in);
		}
	};
#endif // concepts && conditional_explicit

	/// class tuple_size
	template <typename... _Elements>
	struct tuple_size<tuple<_Elements...>>
		: public integral_constant<size_t, sizeof...(_Elements)>
	{
	};

#if __cplusplus >= 201703L
	template <typename... _Types>
	inline constexpr size_t tuple_size_v<tuple<_Types...>> = sizeof...(_Types);

	template <typename... _Types>
	inline constexpr size_t tuple_size_v<const tuple<_Types...>> = sizeof...(_Types);
#endif

	/// Trait to get the Ith element type from a tuple.
	template <size_t __i, typename... _Types>
	struct tuple_element<__i, tuple<_Types...>>
	{
		static_assert(__i < sizeof...(_Types), "tuple index must be in range");

		using type = typename _Nth_type<__i, _Types...>::type;
	};

	template <size_t __i, typename _Head, typename... _Tail>
	constexpr _Head &
	__get_helper(_Tuple_impl<__i, _Head, _Tail...> &__t) noexcept
	{
		return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t);
	}

	template <size_t __i, typename _Head, typename... _Tail>
	constexpr const _Head &
	__get_helper(const _Tuple_impl<__i, _Head, _Tail...> &__t) noexcept
	{
		return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t);
	}

	// Deleted overload to improve diagnostics for invalid indices
	template <size_t __i, typename... _Types>
	__enable_if_t<(__i >= sizeof...(_Types))>
	__get_helper(const tuple<_Types...> &) = delete;

	/// Return a reference to the ith element of a tuple.
	template <size_t __i, typename... _Elements>
	constexpr __tuple_element_t<__i, tuple<_Elements...>> &
	get(tuple<_Elements...> &__t) noexcept
	{
		return std::__get_helper<__i>(__t);
	}

	/// Return a const reference to the ith element of a const tuple.
	template <size_t __i, typename... _Elements>
	constexpr const __tuple_element_t<__i, tuple<_Elements...>> &
	get(const tuple<_Elements...> &__t) noexcept
	{
		return std::__get_helper<__i>(__t);
	}

	/// Return an rvalue reference to the ith element of a tuple rvalue.
	template <size_t __i, typename... _Elements>
	constexpr __tuple_element_t<__i, tuple<_Elements...>> &&
	get(tuple<_Elements...> &&__t) noexcept
	{
		typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
		return std::forward<__element_type>(std::__get_helper<__i>(__t));
	}

	/// Return a const rvalue reference to the ith element of a const tuple rvalue.
	template <size_t __i, typename... _Elements>
	constexpr const __tuple_element_t<__i, tuple<_Elements...>> &&
	get(const tuple<_Elements...> &&__t) noexcept
	{
		typedef __tuple_element_t<__i, tuple<_Elements...>> __element_type;
		return std::forward<const __element_type>(std::__get_helper<__i>(__t));
	}

	/// @cond undocumented
	// Deleted overload chosen for invalid indices.
	template <size_t __i, typename... _Elements>
	constexpr __enable_if_t<(__i >= sizeof...(_Elements))>
	get(const tuple<_Elements...> &) = delete;
	/// @endcond

#ifdef __cpp_lib_tuples_by_type // C++ >= 14
	/// Return a reference to the unique element of type _Tp of a tuple.
	template <typename _Tp, typename... _Types>
	constexpr _Tp &
	get(tuple<_Types...> &__t) noexcept
	{
		constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
		static_assert(__idx < sizeof...(_Types),
					  "the type T in std::get<T> must occur exactly once in the tuple");
		return std::__get_helper<__idx>(__t);
	}

	/// Return a reference to the unique element of type _Tp of a tuple rvalue.
	template <typename _Tp, typename... _Types>
	constexpr _Tp &&
	get(tuple<_Types...> &&__t) noexcept
	{
		constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
		static_assert(__idx < sizeof...(_Types),
					  "the type T in std::get<T> must occur exactly once in the tuple");
		return std::forward<_Tp>(std::__get_helper<__idx>(__t));
	}

	/// Return a const reference to the unique element of type _Tp of a tuple.
	template <typename _Tp, typename... _Types>
	constexpr const _Tp &
	get(const tuple<_Types...> &__t) noexcept
	{
		constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
		static_assert(__idx < sizeof...(_Types),
					  "the type T in std::get<T> must occur exactly once in the tuple");
		return std::__get_helper<__idx>(__t);
	}

	/// Return a const reference to the unique element of type _Tp of
	/// a const tuple rvalue.
	template <typename _Tp, typename... _Types>
	constexpr const _Tp &&
	get(const tuple<_Types...> &&__t) noexcept
	{
		constexpr size_t __idx = __find_uniq_type_in_pack<_Tp, _Types...>();
		static_assert(__idx < sizeof...(_Types),
					  "the type T in std::get<T> must occur exactly once in the tuple");
		return std::forward<const _Tp>(std::__get_helper<__idx>(__t));
	}
#endif

#if __cpp_lib_three_way_comparison
	template <typename... _Tps, typename... _Ups>
		requires(sizeof...(_Tps) == sizeof...(_Ups)) && (requires(const _Tps &__t, const _Ups &__u) {
					{ __t == __u } -> __detail::__boolean_testable;
				} && ...)
	constexpr bool
	operator== [[nodiscard]] (const tuple<_Tps...> &__t,
							  const tuple<_Ups...> &__u)
	{
		return [&]<size_t... _Inds>(index_sequence<_Inds...>)
		{
			// Fold == over the tuples until non-equal elements are found.
			return ((std::get<_Inds>(__t) == std::get<_Inds>(__u)) && ...);
		}(index_sequence_for<_Tps...>{});
	}

	template <typename _Cat, typename _Tp, typename _Up, typename _IndexSeq>
	[[nodiscard]]
	constexpr _Cat
	__tuple_cmp(const _Tp &__t, const _Up &__u, _IndexSeq __indices)
	{
		_Cat __c = _Cat::equivalent;

		// Set __c to the comparison result of two corresponding elements.
		// Return true they are equivalent.
		auto __cmp = [&]<size_t _Ind>(integral_constant<size_t, _Ind>)
		{
			__c = __detail::__synth3way(std::get<_Ind>(__t), std::get<_Ind>(__u));
			return __c == 0;
		};

		[&]<size_t... _Inds>(index_sequence<_Inds...>)
		{
			// Fold __cmp over the tuples until non-equivalent elements are found.
			(void)(__cmp(integral_constant<size_t, _Inds>{}) && ...);
		}(__indices);

		return __c;
	}

	template <typename... _Tps, typename... _Ups>
		requires(sizeof...(_Tps) == sizeof...(_Ups)) && (requires { typename __detail::__synth3way_t<_Tps, _Ups>; } && ...)
	constexpr common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>
	operator<=> [[nodiscard]] (const tuple<_Tps...> &__t,
							   const tuple<_Ups...> &__u)
	{
		using _Cat = common_comparison_category_t<__detail::__synth3way_t<_Tps, _Ups>...>;
		return std::__tuple_cmp<_Cat>(__t, __u, index_sequence_for<_Tps...>());
	}
#else

	// This class performs the comparison operations on tuples
	template <typename _Tp, typename _Up, size_t __i, size_t __size>
	struct __tuple_compare
	{
		static constexpr bool
		__eq(const _Tp &__t, const _Up &__u)
		{
			return bool(std::get<__i>(__t) == std::get<__i>(__u)) && __tuple_compare<_Tp, _Up, __i + 1, __size>::__eq(__t, __u);
		}

		static constexpr bool
		__less(const _Tp &__t, const _Up &__u)
		{
			return bool(std::get<__i>(__t) < std::get<__i>(__u)) || (!bool(std::get<__i>(__u) < std::get<__i>(__t)) && __tuple_compare<_Tp, _Up, __i + 1, __size>::__less(__t, __u));
		}
	};

	template <typename _Tp, typename _Up, size_t __size>
	struct __tuple_compare<_Tp, _Up, __size, __size>
	{
		static constexpr bool
		__eq(const _Tp &, const _Up &) { return true; }

		static constexpr bool
		__less(const _Tp &, const _Up &) { return false; }
	};

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator==(const tuple<_TElements...> &__t,
			   const tuple<_UElements...> &__u)
	{
		static_assert(sizeof...(_TElements) == sizeof...(_UElements),
					  "tuple objects can only be compared if they have equal sizes.");
		using __compare = __tuple_compare<tuple<_TElements...>,
										  tuple<_UElements...>,
										  0, sizeof...(_TElements)>;
		return __compare::__eq(__t, __u);
	}

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator<(const tuple<_TElements...> &__t,
			  const tuple<_UElements...> &__u)
	{
		static_assert(sizeof...(_TElements) == sizeof...(_UElements),
					  "tuple objects can only be compared if they have equal sizes.");
		using __compare = __tuple_compare<tuple<_TElements...>,
										  tuple<_UElements...>,
										  0, sizeof...(_TElements)>;
		return __compare::__less(__t, __u);
	}

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator!=(const tuple<_TElements...> &__t,
			   const tuple<_UElements...> &__u)
	{
		return !(__t == __u);
	}

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator>(const tuple<_TElements...> &__t,
			  const tuple<_UElements...> &__u)
	{
		return __u < __t;
	}

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator<=(const tuple<_TElements...> &__t,
			   const tuple<_UElements...> &__u)
	{
		return !(__u < __t);
	}

	template <typename... _TElements, typename... _UElements>
	_GLIBCXX_NODISCARD constexpr bool
	operator>=(const tuple<_TElements...> &__t,
			   const tuple<_UElements...> &__u)
	{
		return !(__t < __u);
	}
#endif					 // three_way_comparison

	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	// 2275. Why is forward_as_tuple not constexpr?
	/// Create a tuple of lvalue or rvalue references to the arguments
	template <typename... _Elements>
	constexpr tuple<_Elements &&...>
	forward_as_tuple(_Elements &&...__args) noexcept
	{
		return tuple<_Elements &&...>(std::forward<_Elements>(__args)...);
	}

	/// @cond undocumented
	template <size_t, typename, typename, size_t>
	struct __make_tuple_impl;

	template <size_t _Idx, typename _Tuple, typename... _Tp, size_t _Nm>
	struct __make_tuple_impl<_Idx, tuple<_Tp...>, _Tuple, _Nm>
		: __make_tuple_impl<_Idx + 1,
							tuple<_Tp..., __tuple_element_t<_Idx, _Tuple>>,
							_Tuple, _Nm>
	{
	};

	template <size_t _Nm, typename _Tuple, typename... _Tp>
	struct __make_tuple_impl<_Nm, tuple<_Tp...>, _Tuple, _Nm>
	{
		typedef tuple<_Tp...> __type;
	};

	template <typename _Tuple>
	struct __do_make_tuple
		: __make_tuple_impl<0, tuple<>, _Tuple, tuple_size<_Tuple>::value>
	{
	};

	// Returns the std::tuple equivalent of a tuple-like type.
	template <typename _Tuple>
	struct __make_tuple
		: public __do_make_tuple<__remove_cvref_t<_Tuple>>
	{
	};

	// Combines several std::tuple's into a single one.
	template <typename...>
	struct __combine_tuples;

	template <>
	struct __combine_tuples<>
	{
		typedef tuple<> __type;
	};

	template <typename... _Ts>
	struct __combine_tuples<tuple<_Ts...>>
	{
		typedef tuple<_Ts...> __type;
	};

	template <typename... _T1s, typename... _T2s, typename... _Rem>
	struct __combine_tuples<tuple<_T1s...>, tuple<_T2s...>, _Rem...>
	{
		typedef typename __combine_tuples<tuple<_T1s..., _T2s...>,
										  _Rem...>::__type __type;
	};

	// Computes the result type of tuple_cat given a set of tuple-like types.
	template <typename... _Tpls>
	struct __tuple_cat_result
	{
		typedef typename __combine_tuples<typename __make_tuple<_Tpls>::__type...>::__type __type;
	};

	// Helper to determine the index set for the first tuple-like
	// type of a given set.
	template <typename...>
	struct __make_1st_indices;

	template <>
	struct __make_1st_indices<>
	{
		typedef _Index_tuple<> __type;
	};

	// Performs the actual concatenation by step-wise expanding tuple-like
	// objects into the elements,  which are finally forwarded into the
	// result tuple.
	template <typename _Ret, typename _Indices, typename... _Tpls>
	struct __tuple_concater;

	template <typename _Ret, size_t... _Is, typename _Tp, typename... _Tpls>
	struct __tuple_concater<_Ret, _Index_tuple<_Is...>, _Tp, _Tpls...>
	{
		template <typename... _Us>
		static constexpr _Ret
		_S_do(_Tp &&__tp, _Tpls &&...__tps, _Us &&...__us)
		{
			typedef typename __make_1st_indices<_Tpls...>::__type __idx;
			typedef __tuple_concater<_Ret, __idx, _Tpls...> __next;
			return __next::_S_do(std::forward<_Tpls>(__tps)...,
								 std::forward<_Us>(__us)...,
								 std::get<_Is>(std::forward<_Tp>(__tp))...);
		}
	};

	template <typename _Ret>
	struct __tuple_concater<_Ret, _Index_tuple<>>
	{
		template <typename... _Us>
		static constexpr _Ret
		_S_do(_Us &&...__us)
		{
			return _Ret(std::forward<_Us>(__us)...);
		}
	};

	template <typename... _Tps>
	struct __is_tuple_like_impl<tuple<_Tps...>> : true_type
	{
	};
	/// @endcond

	/// Create a `tuple` containing all elements from multiple tuple-like objects
#if __cpp_lib_tuple_like // >= C++23
	template <__tuple_like... _Tpls>
#else
	template <typename... _Tpls, typename = typename enable_if<__and_<__is_tuple_like<_Tpls>...>::value>::type>
#endif
	constexpr auto
	tuple_cat(_Tpls &&...__tpls)
		-> typename __tuple_cat_result<_Tpls...>::__type
	{
		typedef typename __tuple_cat_result<_Tpls...>::__type __ret;
		typedef typename __make_1st_indices<_Tpls...>::__type __idx;
		typedef __tuple_concater<__ret, __idx, _Tpls...> __concater;
		return __concater::_S_do(std::forward<_Tpls>(__tpls)...);
	}

	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	// 2301. Why is tie not constexpr?
	/// Return a tuple of lvalue references bound to the arguments
	template <typename... _Elements>
	constexpr tuple<_Elements &...>
	tie(_Elements &...__args) noexcept
	{
		return tuple<_Elements &...>(__args...);
	}

	/// Exchange the values of two tuples
	template <typename... _Elements>
	_GLIBCXX20_CONSTEXPR inline
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
		// Constrained free swap overload, see p0185r1
		typename enable_if<__and_<__is_swappable<_Elements>...>::value>::type
#else
		void
#endif
		swap(tuple<_Elements...> &__x, tuple<_Elements...> &__y) noexcept(noexcept(__x.swap(__y)))
	{
		__x.swap(__y);
	}

#if __cpp_lib_ranges_zip // >= C++23
	template <typename... _Elements>
		requires(is_swappable_v<const _Elements> && ...)
	constexpr void
	swap(const tuple<_Elements...> &__x, const tuple<_Elements...> &__y) noexcept(noexcept(__x.swap(__y)))
	{
		__x.swap(__y);
	}
#endif					 // C++23

#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
	/// Exchange the values of two const tuples (if const elements can be swapped)
	template <typename... _Elements>
	_GLIBCXX20_CONSTEXPR
		typename enable_if<!__and_<__is_swappable<_Elements>...>::value>::type
		swap(tuple<_Elements...> &, tuple<_Elements...> &) = delete;
#endif

	// A class (and instance) which can be used in 'tie' when an element
	// of a tuple is not required.
	// _GLIBCXX14_CONSTEXPR
	// 2933. PR for LWG 2773 could be clearer
	struct _Swallow_assign
	{
		template <class _Tp>
		_GLIBCXX14_CONSTEXPR const _Swallow_assign &
		operator=(const _Tp &) const
		{
			return *this;
		}
	};

	// _GLIBCXX_RESOLVE_LIB_DEFECTS
	// 2773. Making std::ignore constexpr
	/** Used with `std::tie` to ignore an element of a tuple
	 *
	 * When using `std::tie` to assign the elements of a tuple to variables,
	 * unwanted elements can be ignored by using `std::ignore`. For example:
	 *
	 * ```
	 * int x, y;
	 * std::tie(x, std::ignore, y) = std::make_tuple(1, 2, 3);
	 * ```
	 *
	 * This assignment will perform `x=1; std::ignore=2; y=3;` which results
	 * in the second element being ignored.
	 *
	 * @since C++11
	 */
	_GLIBCXX17_INLINE constexpr _Swallow_assign ignore{};

	/// Partial specialization for tuples
	template <typename... _Types, typename _Alloc>
	struct uses_allocator<tuple<_Types...>, _Alloc> : true_type
	{
	};

	// See stl_pair.h...
	/** "piecewise construction" using a tuple of arguments for each member.
	 *
	 * @param __first Arguments for the first member of the pair.
	 * @param __second Arguments for the second member of the pair.
	 *
	 * The elements of each tuple will be used as the constructor arguments
	 * for the data members of the pair.
	 */
	template <class _T1, class _T2>
	template <typename... _Args1, typename... _Args2>
	_GLIBCXX20_CONSTEXPR inline pair<_T1, _T2>::
		pair(piecewise_construct_t,
			 tuple<_Args1...> __first, tuple<_Args2...> __second)
		: pair(__first, __second,
			   typename _Build_index_tuple<sizeof...(_Args1)>::__type(),
			   typename _Build_index_tuple<sizeof...(_Args2)>::__type())
	{
	}

	template <class _T1, class _T2>
	template <typename... _Args1, size_t... _Indexes1,
			  typename... _Args2, size_t... _Indexes2>
	_GLIBCXX20_CONSTEXPR inline pair<_T1, _T2>::
		pair(tuple<_Args1...> &__tuple1, tuple<_Args2...> &__tuple2,
			 _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>)
		: first(std::forward<_Args1>(std::get<_Indexes1>(__tuple1))...),
		  second(std::forward<_Args2>(std::get<_Indexes2>(__tuple2))...)
	{
	}

#if defined(__cpp_lib_apply) || defined(__cpp_lib_make_from_tuple) // C++ >= 17
	// Unpack a std::tuple into a type trait and use its value.
	// For cv std::tuple<_Up> the result is _Trait<_Tp, cv _Up...>::value.
	// For cv std::tuple<_Up>& the result is _Trait<_Tp, cv _Up&...>::value.
	// Otherwise the result is false (because we don't know if std::get throws).
	template <template <typename...> class _Trait, typename _Tp, typename _Tuple>
	inline constexpr bool __unpack_std_tuple = false;

	template <template <typename...> class _Trait, typename _Tp, typename... _Up>
	inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...>> = _Trait<_Tp, _Up...>::value;

	template <template <typename...> class _Trait, typename _Tp, typename... _Up>
	inline constexpr bool __unpack_std_tuple<_Trait, _Tp, tuple<_Up...> &> = _Trait<_Tp, _Up &...>::value;

	template <template <typename...> class _Trait, typename _Tp, typename... _Up>
	inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...>> = _Trait<_Tp, const _Up...>::value;

	template <template <typename...> class _Trait, typename _Tp, typename... _Up>
	inline constexpr bool __unpack_std_tuple<_Trait, _Tp, const tuple<_Up...> &> = _Trait<_Tp, const _Up &...>::value;
#endif

#ifdef __cpp_lib_apply // C++ >= 17
	template <typename _Fn, typename _Tuple, size_t... _Idx>
	constexpr decltype(auto)
	__apply_impl(_Fn &&__f, _Tuple &&__t, index_sequence<_Idx...>)
	{
		return std::__invoke(std::forward<_Fn>(__f),
							 std::get<_Idx>(std::forward<_Tuple>(__t))...);
	}

#if __cpp_lib_tuple_like // >= C++23
	template <typename _Fn, __tuple_like _Tuple>
#else
	template <typename _Fn, typename _Tuple>
#endif
	constexpr decltype(auto)
	apply(_Fn &&__f, _Tuple &&__t) noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
	{
		using _Indices = make_index_sequence<tuple_size_v<remove_reference_t<_Tuple>>>;
		return std::__apply_impl(std::forward<_Fn>(__f),
								 std::forward<_Tuple>(__t),
								 _Indices{});
	}
#endif

#ifdef __cpp_lib_make_from_tuple // C++ >= 17
	template <typename _Tp, typename _Tuple, size_t... _Idx>
	constexpr _Tp
	__make_from_tuple_impl(_Tuple &&__t, index_sequence<_Idx...>)
	{
		return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...);
	}

#if __cpp_lib_tuple_like // >= C++23
	template <typename _Tp, __tuple_like _Tuple>
#else
	template <typename _Tp, typename _Tuple>
#endif
	constexpr _Tp
	make_from_tuple(_Tuple &&__t) noexcept(__unpack_std_tuple<is_nothrow_constructible, _Tp, _Tuple>)
	{
		constexpr size_t __n = tuple_size_v<remove_reference_t<_Tuple>>;
#if __has_builtin(__reference_constructs_from_temporary)
		if constexpr (__n == 1)
		{
			using _Elt = decltype(std::get<0>(std::declval<_Tuple>()));
			static_assert(!__reference_constructs_from_temporary(_Tp, _Elt));
		}
#endif
		return __make_from_tuple_impl<_Tp>(std::forward<_Tuple>(__t),
										   make_index_sequence<__n>{});
	}
#endif

#if __cpp_lib_tuple_like // >= C++23
	template <__tuple_like _TTuple, __tuple_like _UTuple,
			  template <typename> class _TQual, template <typename> class _UQual,
			  typename = make_index_sequence<tuple_size_v<_TTuple>>>
	struct __tuple_like_common_reference;

	template <__tuple_like _TTuple, __tuple_like _UTuple,
			  template <typename> class _TQual, template <typename> class _UQual,
			  size_t... _Is>
		requires requires { typename tuple<common_reference_t<_TQual<tuple_element_t<_Is, _TTuple>>,
															  _UQual<tuple_element_t<_Is, _UTuple>>>...>; }
	struct __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual, index_sequence<_Is...>>
	{
		using type = tuple<common_reference_t<_TQual<tuple_element_t<_Is, _TTuple>>,
											  _UQual<tuple_element_t<_Is, _UTuple>>>...>;
	};

	template <__tuple_like _TTuple, __tuple_like _UTuple,
			  template <typename> class _TQual, template <typename> class _UQual>
		requires(__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>) && is_same_v<_TTuple, decay_t<_TTuple>> && is_same_v<_UTuple, decay_t<_UTuple>> && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>) && requires { typename __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual>::type; }
	struct basic_common_reference<_TTuple, _UTuple, _TQual, _UQual>
	{
		using type = typename __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual>::type;
	};

	template <__tuple_like _TTuple, __tuple_like _UTuple,
			  typename = make_index_sequence<tuple_size_v<_TTuple>>>
	struct __tuple_like_common_type;

	template <__tuple_like _TTuple, __tuple_like _UTuple, size_t... _Is>
		requires requires { typename tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
														 tuple_element_t<_Is, _UTuple>>...>; }
	struct __tuple_like_common_type<_TTuple, _UTuple, index_sequence<_Is...>>
	{
		using type = tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
										 tuple_element_t<_Is, _UTuple>>...>;
	};

	template <__tuple_like _TTuple, __tuple_like _UTuple>
		requires(__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>) && is_same_v<_TTuple, decay_t<_TTuple>> && is_same_v<_UTuple, decay_t<_UTuple>> && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>) && requires { typename __tuple_like_common_type<_TTuple, _UTuple>::type; }
	struct common_type<_TTuple, _UTuple>
	{
		using type = typename __tuple_like_common_type<_TTuple, _UTuple>::type;
	};
#endif					 // C++23

	/// @}

#undef __glibcxx_no_dangling_refs

	_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++11

#endif // _GLIBCXX_TUPLE
#else
#include_next <tuple>
#endif