xref: /freebsd/contrib/llvm-project/libcxx/include/tuple (revision 59c8e88e72633afbc47a4ace0d2170d00d51f7dc)
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_TUPLE
11#define _LIBCPP_TUPLE
12
13/*
14    tuple synopsis
15
16namespace std
17{
18
19template <class... T>
20class tuple {
21public:
22    explicit(see-below) constexpr tuple();
23    explicit(see-below) tuple(const T&...);  // constexpr in C++14
24    template <class... U>
25        explicit(see-below) tuple(U&&...);  // constexpr in C++14
26    tuple(const tuple&) = default;
27    tuple(tuple&&) = default;
28
29    template<class... UTypes>
30        constexpr explicit(see-below) tuple(tuple<UTypes...>&);  // C++23
31    template <class... U>
32        explicit(see-below) tuple(const tuple<U...>&);  // constexpr in C++14
33    template <class... U>
34        explicit(see-below) tuple(tuple<U...>&&);  // constexpr in C++14
35    template<class... UTypes>
36        constexpr explicit(see-below) tuple(const tuple<UTypes...>&&); // C++23
37
38    template<class U1, class U2>
39        constexpr explicit(see-below) tuple(pair<U1, U2>&);  // iff sizeof...(Types) == 2 // C++23
40    template <class U1, class U2>
41        explicit(see-below) tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14
42    template <class U1, class U2>
43        explicit(see-below) tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14
44    template<class U1, class U2>
45        constexpr explicit(see-below) tuple(const pair<U1, U2>&&);  // iff sizeof...(Types) == 2 // C++23
46
47    // allocator-extended constructors
48    template <class Alloc>
49        tuple(allocator_arg_t, const Alloc& a);
50    template <class Alloc>
51        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const T&...);          // constexpr in C++20
52    template <class Alloc, class... U>
53        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, U&&...);               // constexpr in C++20
54    template <class Alloc>
55        tuple(allocator_arg_t, const Alloc& a, const tuple&);                             // constexpr in C++20
56    template <class Alloc>
57        tuple(allocator_arg_t, const Alloc& a, tuple&&);                                  // constexpr in C++20
58    template<class Alloc, class... UTypes>
59        constexpr explicit(see-below)
60          tuple(allocator_arg_t, const Alloc& a, tuple<UTypes...>&);                      // C++23
61    template <class Alloc, class... U>
62        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);   // constexpr in C++20
63    template <class Alloc, class... U>
64        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);        // constexpr in C++20
65    template<class Alloc, class... UTypes>
66        constexpr explicit(see-below)
67          tuple(allocator_arg_t, const Alloc& a, const tuple<UTypes...>&&);               // C++23
68    template<class Alloc, class U1, class U2>
69        constexpr explicit(see-below)
70          tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&);                          // C++23
71    template <class Alloc, class U1, class U2>
72        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);  // constexpr in C++20
73    template <class Alloc, class U1, class U2>
74        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);       // constexpr in C++20
75    template<class Alloc, class U1, class U2>
76        constexpr explicit(see-below)
77          tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&&);                   // C++23
78
79    tuple& operator=(const tuple&);                                                       // constexpr in C++20
80    constexpr const tuple& operator=(const tuple&) const;                                 // C++23
81    tuple& operator=(tuple&&) noexcept(is_nothrow_move_assignable_v<T> && ...);           // constexpr in C++20
82    constexpr const tuple& operator=(tuple&&) const;                                      // C++23
83    template <class... U>
84        tuple& operator=(const tuple<U...>&);                                             // constexpr in C++20
85    template<class... UTypes>
86        constexpr const tuple& operator=(const tuple<UTypes...>&) const;                  // C++23
87    template <class... U>
88        tuple& operator=(tuple<U...>&&);                                                  // constexpr in C++20
89    template<class... UTypes>
90        constexpr const tuple& operator=(tuple<UTypes...>&&) const;                       // C++23
91    template <class U1, class U2>
92        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2                   // constexpr in C++20
93    template<class U1, class U2>
94        constexpr const tuple& operator=(const pair<U1, U2>&) const;   // iff sizeof...(Types) == 2 // C++23
95    template <class U1, class U2>
96        tuple& operator=(pair<U1, U2>&&); // iff sizeof...(T) == 2                        // constexpr in C++20
97    template<class U1, class U2>
98        constexpr const tuple& operator=(pair<U1, U2>&&) const;  // iff sizeof...(Types) == 2 // C++23
99
100    template<class U, size_t N>
101        tuple& operator=(array<U, N> const&) // iff sizeof...(T) == N, EXTENSION
102    template<class U, size_t N>
103        tuple& operator=(array<U, N>&&) // iff sizeof...(T) == N, EXTENSION
104
105    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));               // constexpr in C++20
106    constexpr void swap(const tuple&) const noexcept(see-below);                          // C++23
107};
108
109
110template<class... TTypes, class... UTypes, template<class> class TQual, template<class> class UQual> // since C++23
111  requires requires { typename tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>; }
112struct basic_common_reference<tuple<TTypes...>, tuple<UTypes...>, TQual, UQual> {
113  using type = tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>;
114};
115
116template<class... TTypes, class... UTypes>                                // since C++23
117  requires requires { typename tuple<common_type_t<TTypes, UTypes>...>; }
118struct common_type<tuple<TTypes...>, tuple<UTypes...>> {
119  using type = tuple<common_type_t<TTypes, UTypes>...>;
120};
121
122template <class ...T>
123tuple(T...) -> tuple<T...>;                                         // since C++17
124template <class T1, class T2>
125tuple(pair<T1, T2>) -> tuple<T1, T2>;                               // since C++17
126template <class Alloc, class ...T>
127tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>;                 // since C++17
128template <class Alloc, class T1, class T2>
129tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;       // since C++17
130template <class Alloc, class ...T>
131tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>;          // since C++17
132
133inline constexpr unspecified ignore;
134
135template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
136template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
137template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14
138template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
139
140// [tuple.apply], calling a function with a tuple of arguments:
141template <class F, class Tuple>
142  constexpr decltype(auto) apply(F&& f, Tuple&& t); // C++17
143template <class T, class Tuple>
144  constexpr T make_from_tuple(Tuple&& t); // C++17
145
146// 20.4.1.4, tuple helper classes:
147template <class T> struct tuple_size; // undefined
148template <class... T> struct tuple_size<tuple<T...>>;
149template <class T>
150 inline constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17
151template <size_t I, class T> struct tuple_element; // undefined
152template <size_t I, class... T> struct tuple_element<I, tuple<T...>>;
153template <size_t I, class T>
154  using tuple_element_t = typename tuple_element <I, T>::type; // C++14
155
156// 20.4.1.5, element access:
157template <size_t I, class... T>
158    typename tuple_element<I, tuple<T...>>::type&
159    get(tuple<T...>&) noexcept; // constexpr in C++14
160template <size_t I, class... T>
161    const typename tuple_element<I, tuple<T...>>::type&
162    get(const tuple<T...>&) noexcept; // constexpr in C++14
163template <size_t I, class... T>
164    typename tuple_element<I, tuple<T...>>::type&&
165    get(tuple<T...>&&) noexcept; // constexpr in C++14
166template <size_t I, class... T>
167    const typename tuple_element<I, tuple<T...>>::type&&
168    get(const tuple<T...>&&) noexcept; // constexpr in C++14
169
170template <class T1, class... T>
171    constexpr T1& get(tuple<T...>&) noexcept;  // C++14
172template <class T1, class... T>
173    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14
174template <class T1, class... T>
175    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14
176template <class T1, class... T>
177    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14
178
179// 20.4.1.6, relational operators:
180template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14
181template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
182template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
183template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20
184template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
185template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20
186template<class... T, class... U>
187  constexpr common_comparison_category_t<synth-three-way-result<T, U>...>
188    operator<=>(const tuple<T...>&, const tuple<U...>&);                                  // since C++20
189
190template <class... Types, class Alloc>
191  struct uses_allocator<tuple<Types...>, Alloc>;
192
193template <class... Types>
194  void
195  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));
196
197template <class... Types>
198  constexpr void swap(const tuple<Types...>& x, const tuple<Types...>& y) noexcept(see-below);   // C++23
199
200}  // std
201
202*/
203
204#include <__assert> // all public C++ headers provide the assertion handler
205#include <__compare/common_comparison_category.h>
206#include <__compare/synth_three_way.h>
207#include <__config>
208#include <__functional/invoke.h>
209#include <__fwd/array.h>
210#include <__fwd/get.h>
211#include <__fwd/tuple.h>
212#include <__memory/allocator_arg_t.h>
213#include <__memory/uses_allocator.h>
214#include <__tuple/make_tuple_types.h>
215#include <__tuple/sfinae_helpers.h>
216#include <__tuple/tuple_element.h>
217#include <__tuple/tuple_indices.h>
218#include <__tuple/tuple_like_ext.h>
219#include <__tuple/tuple_size.h>
220#include <__tuple/tuple_types.h>
221#include <__type_traits/apply_cv.h>
222#include <__type_traits/common_reference.h>
223#include <__type_traits/common_type.h>
224#include <__type_traits/conditional.h>
225#include <__type_traits/conjunction.h>
226#include <__type_traits/copy_cvref.h>
227#include <__type_traits/disjunction.h>
228#include <__type_traits/is_arithmetic.h>
229#include <__type_traits/is_assignable.h>
230#include <__type_traits/is_constructible.h>
231#include <__type_traits/is_convertible.h>
232#include <__type_traits/is_copy_assignable.h>
233#include <__type_traits/is_copy_constructible.h>
234#include <__type_traits/is_default_constructible.h>
235#include <__type_traits/is_empty.h>
236#include <__type_traits/is_final.h>
237#include <__type_traits/is_implicitly_default_constructible.h>
238#include <__type_traits/is_move_assignable.h>
239#include <__type_traits/is_move_constructible.h>
240#include <__type_traits/is_nothrow_assignable.h>
241#include <__type_traits/is_nothrow_constructible.h>
242#include <__type_traits/is_nothrow_copy_assignable.h>
243#include <__type_traits/is_nothrow_copy_constructible.h>
244#include <__type_traits/is_nothrow_default_constructible.h>
245#include <__type_traits/is_nothrow_move_assignable.h>
246#include <__type_traits/is_reference.h>
247#include <__type_traits/is_same.h>
248#include <__type_traits/is_swappable.h>
249#include <__type_traits/lazy.h>
250#include <__type_traits/maybe_const.h>
251#include <__type_traits/nat.h>
252#include <__type_traits/negation.h>
253#include <__type_traits/remove_cvref.h>
254#include <__type_traits/remove_reference.h>
255#include <__type_traits/unwrap_ref.h>
256#include <__utility/forward.h>
257#include <__utility/integer_sequence.h>
258#include <__utility/move.h>
259#include <__utility/pair.h>
260#include <__utility/piecewise_construct.h>
261#include <__utility/swap.h>
262#include <cstddef>
263#include <version>
264
265// standard-mandated includes
266
267// [tuple.syn]
268#include <compare>
269
270#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
271#  pragma GCC system_header
272#endif
273
274_LIBCPP_PUSH_MACROS
275#include <__undef_macros>
276
277_LIBCPP_BEGIN_NAMESPACE_STD
278
279#ifndef _LIBCPP_CXX03_LANG
280
281
282// __tuple_leaf
283
284template <size_t _Ip, class _Hp,
285          bool=is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value
286         >
287class __tuple_leaf;
288
289template <size_t _Ip, class _Hp, bool _Ep>
290inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
291void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
292    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
293{
294    swap(__x.get(), __y.get());
295}
296
297template <size_t _Ip, class _Hp, bool _Ep>
298_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
299void swap(const __tuple_leaf<_Ip, _Hp, _Ep>& __x, const __tuple_leaf<_Ip, _Hp, _Ep>& __y)
300     _NOEXCEPT_(__is_nothrow_swappable<const _Hp>::value) {
301  swap(__x.get(), __y.get());
302}
303
304template <size_t _Ip, class _Hp, bool>
305class __tuple_leaf
306{
307    _Hp __value_;
308
309    template <class _Tp>
310    static _LIBCPP_HIDE_FROM_ABI constexpr bool __can_bind_reference() {
311#if __has_keyword(__reference_binds_to_temporary)
312      return !__reference_binds_to_temporary(_Hp, _Tp);
313#else
314      return true;
315#endif
316    }
317
318    _LIBCPP_CONSTEXPR_SINCE_CXX14
319    __tuple_leaf& operator=(const __tuple_leaf&);
320public:
321    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
322             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : __value_()
323       {static_assert(!is_reference<_Hp>::value,
324              "Attempted to default construct a reference element in a tuple");}
325
326    template <class _Alloc>
327        _LIBCPP_INLINE_VISIBILITY constexpr
328        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
329            : __value_()
330        {static_assert(!is_reference<_Hp>::value,
331              "Attempted to default construct a reference element in a tuple");}
332
333    template <class _Alloc>
334        _LIBCPP_INLINE_VISIBILITY constexpr
335        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
336            : __value_(allocator_arg_t(), __a)
337        {static_assert(!is_reference<_Hp>::value,
338              "Attempted to default construct a reference element in a tuple");}
339
340    template <class _Alloc>
341        _LIBCPP_INLINE_VISIBILITY constexpr
342        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
343            : __value_(__a)
344        {static_assert(!is_reference<_Hp>::value,
345              "Attempted to default construct a reference element in a tuple");}
346
347    template <class _Tp,
348              class = __enable_if_t<
349                  _And<
350                      _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>,
351                      is_constructible<_Hp, _Tp>
352                    >::value
353                >
354            >
355        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
356        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
357            : __value_(_VSTD::forward<_Tp>(__t))
358        {static_assert(__can_bind_reference<_Tp&&>(),
359       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
360
361    template <class _Tp, class _Alloc>
362        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
363        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
364            : __value_(_VSTD::forward<_Tp>(__t))
365        {static_assert(__can_bind_reference<_Tp&&>(),
366       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
367
368    template <class _Tp, class _Alloc>
369        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
370        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
371            : __value_(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
372        {static_assert(!is_reference<_Hp>::value,
373            "Attempted to uses-allocator construct a reference element in a tuple");}
374
375    template <class _Tp, class _Alloc>
376        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
377        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
378            : __value_(_VSTD::forward<_Tp>(__t), __a)
379        {static_assert(!is_reference<_Hp>::value,
380           "Attempted to uses-allocator construct a reference element in a tuple");}
381
382    _LIBCPP_HIDE_FROM_ABI __tuple_leaf(const __tuple_leaf& __t) = default;
383    _LIBCPP_HIDE_FROM_ABI __tuple_leaf(__tuple_leaf&& __t) = default;
384
385    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
386    int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
387    {
388        _VSTD::swap(*this, __t);
389        return 0;
390    }
391
392    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
393    int swap(const __tuple_leaf& __t) const _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {
394        _VSTD::swap(*this, __t);
395        return 0;
396    }
397
398    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14       _Hp& get()       _NOEXCEPT {return __value_;}
399    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {return __value_;}
400};
401
402template <size_t _Ip, class _Hp>
403class __tuple_leaf<_Ip, _Hp, true>
404    : private _Hp
405{
406    _LIBCPP_CONSTEXPR_SINCE_CXX14
407    __tuple_leaf& operator=(const __tuple_leaf&);
408public:
409    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
410             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
411
412    template <class _Alloc>
413        _LIBCPP_INLINE_VISIBILITY constexpr
414        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
415
416    template <class _Alloc>
417        _LIBCPP_INLINE_VISIBILITY constexpr
418        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
419            : _Hp(allocator_arg_t(), __a) {}
420
421    template <class _Alloc>
422        _LIBCPP_INLINE_VISIBILITY constexpr
423        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
424            : _Hp(__a) {}
425
426    template <class _Tp,
427              class = __enable_if_t<
428                  _And<
429                    _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>,
430                    is_constructible<_Hp, _Tp>
431                  >::value
432                >
433            >
434        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
435        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
436            : _Hp(_VSTD::forward<_Tp>(__t)) {}
437
438    template <class _Tp, class _Alloc>
439        _LIBCPP_INLINE_VISIBILITY constexpr
440        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
441            : _Hp(_VSTD::forward<_Tp>(__t)) {}
442
443    template <class _Tp, class _Alloc>
444        _LIBCPP_INLINE_VISIBILITY constexpr
445        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
446            : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
447
448    template <class _Tp, class _Alloc>
449        _LIBCPP_INLINE_VISIBILITY constexpr
450        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
451            : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
452
453    __tuple_leaf(__tuple_leaf const &) = default;
454    __tuple_leaf(__tuple_leaf &&) = default;
455
456    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
457    int
458    swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
459    {
460        _VSTD::swap(*this, __t);
461        return 0;
462    }
463
464    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
465    int swap(const __tuple_leaf& __rhs) const _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {
466        _VSTD::swap(*this, __rhs);
467        return 0;
468    }
469
470    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
471    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
472};
473
474template <class ..._Tp>
475_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
476void __swallow(_Tp&&...) _NOEXCEPT {}
477
478template <class _Tp>
479struct __all_default_constructible;
480
481template <class ..._Tp>
482struct __all_default_constructible<__tuple_types<_Tp...>>
483    : __all<is_default_constructible<_Tp>::value...>
484{ };
485
486// __tuple_impl
487
488template<class _Indx, class ..._Tp> struct __tuple_impl;
489
490template<size_t ..._Indx, class ..._Tp>
491struct _LIBCPP_DECLSPEC_EMPTY_BASES __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
492    : public __tuple_leaf<_Indx, _Tp>...
493{
494    _LIBCPP_INLINE_VISIBILITY
495    constexpr __tuple_impl()
496        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
497
498    template <size_t ..._Uf, class ..._Tf,
499              size_t ..._Ul, class ..._Tl, class ..._Up>
500        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
501        explicit
502        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
503                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
504                     _Up&&... __u)
505                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
506                                 __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
507            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
508            __tuple_leaf<_Ul, _Tl>()...
509            {}
510
511    template <class _Alloc, size_t ..._Uf, class ..._Tf,
512              size_t ..._Ul, class ..._Tl, class ..._Up>
513        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
514        explicit
515        __tuple_impl(allocator_arg_t, const _Alloc& __a,
516                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
517                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
518                     _Up&&... __u) :
519            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
520            _VSTD::forward<_Up>(__u))...,
521            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
522            {}
523
524    template <class _Tuple,
525              class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value>
526             >
527        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
528        __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
529                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
530            : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
531                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
532            {}
533
534    template <class _Alloc, class _Tuple,
535              class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value>
536             >
537        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
538        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
539            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
540                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a,
541                                       _VSTD::forward<typename tuple_element<_Indx,
542                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
543            {}
544
545    __tuple_impl(const __tuple_impl&) = default;
546    __tuple_impl(__tuple_impl&&) = default;
547
548    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
549    void swap(__tuple_impl& __t)
550        _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
551    {
552        _VSTD::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
553    }
554
555    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
556    void swap(const __tuple_impl& __t) const
557        _NOEXCEPT_(__all<__is_nothrow_swappable<const _Tp>::value...>::value)
558    {
559        _VSTD::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t))...);
560    }
561};
562
563template<class _Dest, class _Source, size_t ..._Np>
564_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
565void __memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {
566    _VSTD::__swallow(((_VSTD::get<_Np>(__dest) = _VSTD::get<_Np>(__source)), void(), 0)...);
567}
568
569template<class _Dest, class _Source, class ..._Up, size_t ..._Np>
570_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
571void __memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {
572    _VSTD::__swallow(((
573        _VSTD::get<_Np>(__dest) = _VSTD::forward<_Up>(_VSTD::get<_Np>(__source))
574    ), void(), 0)...);
575}
576
577template <class ..._Tp>
578class _LIBCPP_TEMPLATE_VIS tuple
579{
580    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;
581
582    _BaseT __base_;
583
584    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
585        typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
586    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
587        const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
588    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
589        typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
590    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
591        const typename tuple_element<_Jp, tuple<_Up...> >::type&& get(const tuple<_Up...>&&) _NOEXCEPT;
592public:
593    // [tuple.cnstr]
594
595    // tuple() constructors (including allocator_arg_t variants)
596    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
597        _And<
598            _IsImpDefault<_Tp>... // explicit check
599        >::value
600    , int> = 0>
601    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
602    tuple()
603        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
604    { }
605
606    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
607              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
608        _And<
609            _IsDefault<_Tp>...,
610            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
611        >::value
612    , int> = 0>
613    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
614    explicit tuple()
615        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
616    { }
617
618    template <class _Alloc, template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
619        _And<
620            _IsImpDefault<_Tp>... // explicit check
621        >::value
622    , int> = 0>
623    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
624    tuple(allocator_arg_t, _Alloc const& __a)
625      : __base_(allocator_arg_t(), __a,
626                    __tuple_indices<>(), __tuple_types<>(),
627                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
628                    __tuple_types<_Tp...>()) {}
629
630    template <class _Alloc,
631              template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
632              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
633        _And<
634            _IsDefault<_Tp>...,
635            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
636        >::value
637    , int> = 0>
638    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
639    explicit tuple(allocator_arg_t, _Alloc const& __a)
640      : __base_(allocator_arg_t(), __a,
641                    __tuple_indices<>(), __tuple_types<>(),
642                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
643                    __tuple_types<_Tp...>()) {}
644
645    // tuple(const T&...) constructors (including allocator_arg_t variants)
646    template <template<class...> class _And = _And, __enable_if_t<
647        _And<
648            _BoolConstant<sizeof...(_Tp) >= 1>,
649            is_copy_constructible<_Tp>...,
650            is_convertible<const _Tp&, _Tp>... // explicit check
651        >::value
652    , int> = 0>
653    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
654    tuple(const _Tp& ... __t)
655        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
656        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
657                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
658                typename __make_tuple_indices<0>::type(),
659                typename __make_tuple_types<tuple, 0>::type(),
660                __t...
661               ) {}
662
663    template <template<class...> class _And = _And, __enable_if_t<
664        _And<
665            _BoolConstant<sizeof...(_Tp) >= 1>,
666            is_copy_constructible<_Tp>...,
667            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
668        >::value
669    , int> = 0>
670    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
671    explicit tuple(const _Tp& ... __t)
672        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
673        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
674                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
675                typename __make_tuple_indices<0>::type(),
676                typename __make_tuple_types<tuple, 0>::type(),
677                __t...
678               ) {}
679
680    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
681        _And<
682            _BoolConstant<sizeof...(_Tp) >= 1>,
683            is_copy_constructible<_Tp>...,
684            is_convertible<const _Tp&, _Tp>... // explicit check
685        >::value
686    , int> = 0>
687    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
688    tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
689        : __base_(allocator_arg_t(), __a,
690                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
691                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
692                typename __make_tuple_indices<0>::type(),
693                typename __make_tuple_types<tuple, 0>::type(),
694                __t...
695               ) {}
696
697    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
698        _And<
699            _BoolConstant<sizeof...(_Tp) >= 1>,
700            is_copy_constructible<_Tp>...,
701            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
702        >::value
703    , int> = 0>
704    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
705    explicit tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
706        : __base_(allocator_arg_t(), __a,
707                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
708                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
709                typename __make_tuple_indices<0>::type(),
710                typename __make_tuple_types<tuple, 0>::type(),
711                __t...
712               ) {}
713
714    // tuple(U&& ...) constructors (including allocator_arg_t variants)
715    template <class ..._Up> struct _IsThisTuple : false_type { };
716    template <class _Up> struct _IsThisTuple<_Up> : is_same<__remove_cvref_t<_Up>, tuple> { };
717
718    template <class ..._Up>
719    struct _EnableUTypesCtor : _And<
720        _BoolConstant<sizeof...(_Tp) >= 1>,
721        _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
722        is_constructible<_Tp, _Up>...
723    > { };
724
725    template <class ..._Up, __enable_if_t<
726        _And<
727            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
728            _EnableUTypesCtor<_Up...>,
729            is_convertible<_Up, _Tp>... // explicit check
730        >::value
731    , int> = 0>
732    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
733    tuple(_Up&&... __u)
734        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
735        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
736                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
737                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
738                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
739                    _VSTD::forward<_Up>(__u)...) {}
740
741    template <class ..._Up, __enable_if_t<
742        _And<
743            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
744            _EnableUTypesCtor<_Up...>,
745            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
746        >::value
747    , int> = 0>
748    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
749    explicit tuple(_Up&&... __u)
750        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
751        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
752                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
753                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
754                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
755                    _VSTD::forward<_Up>(__u)...) {}
756
757    template <class _Alloc, class ..._Up, __enable_if_t<
758        _And<
759            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
760            _EnableUTypesCtor<_Up...>,
761            is_convertible<_Up, _Tp>... // explicit check
762        >::value
763    , int> = 0>
764    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
765    tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
766        : __base_(allocator_arg_t(), __a,
767                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
768                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
769                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
770                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
771                    _VSTD::forward<_Up>(__u)...) {}
772
773    template <class _Alloc, class ..._Up, __enable_if_t<
774        _And<
775            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
776            _EnableUTypesCtor<_Up...>,
777            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
778        >::value
779    , int> = 0>
780    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
781    explicit tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
782        : __base_(allocator_arg_t(), __a,
783                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
784                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
785                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
786                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
787                    _VSTD::forward<_Up>(__u)...) {}
788
789    // Copy and move constructors (including the allocator_arg_t variants)
790    tuple(const tuple&) = default;
791    tuple(tuple&&) = default;
792
793    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
794        _And<is_copy_constructible<_Tp>...>::value
795    , int> = 0>
796    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
797    tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)
798        : __base_(allocator_arg_t(), __alloc, __t)
799    { }
800
801    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
802        _And<is_move_constructible<_Tp>...>::value
803    , int> = 0>
804    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
805    tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)
806        : __base_(allocator_arg_t(), __alloc, _VSTD::move(__t))
807    { }
808
809    // tuple(const tuple<U...>&) constructors (including allocator_arg_t variants)
810
811    template <class _OtherTuple, class _DecayedOtherTuple = __remove_cvref_t<_OtherTuple>, class = void>
812    struct _EnableCtorFromUTypesTuple : false_type {};
813
814    template <class _OtherTuple, class... _Up>
815    struct _EnableCtorFromUTypesTuple<_OtherTuple, tuple<_Up...>,
816              // the length of the packs needs to checked first otherwise the 2 packs cannot be expanded simultaneously below
817               __enable_if_t<sizeof...(_Up) == sizeof...(_Tp)>> : _And<
818        // the two conditions below are not in spec. The purpose is to disable the UTypes Ctor when copy/move Ctor can work.
819        // Otherwise, is_constructible can trigger hard error in those cases https://godbolt.org/z/M94cGdKcE
820        _Not<is_same<_OtherTuple, const tuple&> >,
821        _Not<is_same<_OtherTuple, tuple&&> >,
822        is_constructible<_Tp, __copy_cvref_t<_OtherTuple, _Up> >...,
823        _Lazy<_Or, _BoolConstant<sizeof...(_Tp) != 1>,
824            // _Tp and _Up are 1-element packs - the pack expansions look
825            // weird to avoid tripping up the type traits in degenerate cases
826            _Lazy<_And,
827                _Not<is_same<_Tp, _Up> >...,
828                _Not<is_convertible<_OtherTuple, _Tp> >...,
829                _Not<is_constructible<_Tp, _OtherTuple> >...
830            >
831        >
832    > {};
833
834    template <class ..._Up, __enable_if_t<
835        _And<
836            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
837            is_convertible<const _Up&, _Tp>... // explicit check
838        >::value
839    , int> = 0>
840    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
841    tuple(const tuple<_Up...>& __t)
842        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
843        : __base_(__t)
844    { }
845
846    template <class ..._Up, __enable_if_t<
847        _And<
848            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
849            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
850        >::value
851    , int> = 0>
852    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
853    explicit tuple(const tuple<_Up...>& __t)
854        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
855        : __base_(__t)
856    { }
857
858    template <class ..._Up, class _Alloc, __enable_if_t<
859        _And<
860            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
861            is_convertible<const _Up&, _Tp>... // explicit check
862        >::value
863    , int> = 0>
864    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
865    tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
866        : __base_(allocator_arg_t(), __a, __t)
867    { }
868
869    template <class ..._Up, class _Alloc, __enable_if_t<
870        _And<
871            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
872            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
873        >::value
874    , int> = 0>
875    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
876    explicit tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
877        : __base_(allocator_arg_t(), __a, __t)
878    { }
879
880#if _LIBCPP_STD_VER >= 23
881    // tuple(tuple<U...>&) constructors (including allocator_arg_t variants)
882
883    template <class... _Up, enable_if_t<
884        _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
885    _LIBCPP_HIDE_FROM_ABI constexpr
886        explicit(!(is_convertible_v<_Up&, _Tp> && ...))
887    tuple(tuple<_Up...>& __t) : __base_(__t) {}
888
889    template <class _Alloc, class... _Up, enable_if_t<
890        _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
891    _LIBCPP_HIDE_FROM_ABI constexpr
892        explicit(!(is_convertible_v<_Up&, _Tp> && ...))
893    tuple(allocator_arg_t, const _Alloc& __alloc, tuple<_Up...>& __t) : __base_(allocator_arg_t(), __alloc, __t) {}
894#endif // _LIBCPP_STD_VER >= 23
895
896    // tuple(tuple<U...>&&) constructors (including allocator_arg_t variants)
897
898    template <class ..._Up, __enable_if_t<
899        _And<
900            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
901            is_convertible<_Up, _Tp>... // explicit check
902        >::value
903    , int> = 0>
904    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
905    tuple(tuple<_Up...>&& __t)
906        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
907        : __base_(_VSTD::move(__t))
908    { }
909
910    template <class ..._Up, __enable_if_t<
911        _And<
912            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
913            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
914        >::value
915    , int> = 0>
916    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
917    explicit tuple(tuple<_Up...>&& __t)
918        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
919        : __base_(_VSTD::move(__t))
920    { }
921
922    template <class _Alloc, class ..._Up, __enable_if_t<
923        _And<
924            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
925            is_convertible<_Up, _Tp>... // explicit check
926        >::value
927    , int> = 0>
928    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
929    tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
930        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
931    { }
932
933    template <class _Alloc, class ..._Up, __enable_if_t<
934        _And<
935            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
936            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
937        >::value
938    , int> = 0>
939    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
940    explicit tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
941        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
942    { }
943
944#if _LIBCPP_STD_VER >= 23
945    // tuple(const tuple<U...>&&) constructors (including allocator_arg_t variants)
946
947    template <class... _Up, enable_if_t<
948        _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
949    _LIBCPP_HIDE_FROM_ABI constexpr
950        explicit(!(is_convertible_v<const _Up&&, _Tp> && ...))
951    tuple(const tuple<_Up...>&& __t) : __base_(std::move(__t)) {}
952
953    template <class _Alloc, class... _Up, enable_if_t<
954        _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
955    _LIBCPP_HIDE_FROM_ABI constexpr
956        explicit(!(is_convertible_v<const _Up&&, _Tp> && ...))
957    tuple(allocator_arg_t, const _Alloc& __alloc, const tuple<_Up...>&& __t)
958        : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}
959#endif // _LIBCPP_STD_VER >= 23
960
961    // tuple(const pair<U1, U2>&) constructors (including allocator_arg_t variants)
962
963    template <template <class...> class _Pred, class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
964    struct _CtorPredicateFromPair : false_type{};
965
966    template <template <class...> class _Pred, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
967    struct _CtorPredicateFromPair<_Pred, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > : _And<
968        _Pred<_Tp1, __copy_cvref_t<_Pair, _Up1> >,
969        _Pred<_Tp2, __copy_cvref_t<_Pair, _Up2> >
970    > {};
971
972    template <class _Pair>
973    struct _EnableCtorFromPair : _CtorPredicateFromPair<is_constructible, _Pair>{};
974
975    template <class _Pair>
976    struct _NothrowConstructibleFromPair : _CtorPredicateFromPair<is_nothrow_constructible, _Pair>{};
977
978    template <class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
979    struct _BothImplicitlyConvertible : false_type{};
980
981    template <class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
982    struct _BothImplicitlyConvertible<_Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > : _And<
983        is_convertible<__copy_cvref_t<_Pair, _Up1>, _Tp1>,
984        is_convertible<__copy_cvref_t<_Pair, _Up2>, _Tp2>
985    > {};
986
987    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
988        _And<
989            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
990            _BothImplicitlyConvertible<const pair<_Up1, _Up2>&> // explicit check
991        >::value
992    , int> = 0>
993    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
994    tuple(const pair<_Up1, _Up2>& __p)
995        _NOEXCEPT_((_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value))
996        : __base_(__p)
997    { }
998
999    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1000        _And<
1001            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
1002            _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> > // explicit check
1003        >::value
1004    , int> = 0>
1005    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1006    explicit tuple(const pair<_Up1, _Up2>& __p)
1007        _NOEXCEPT_((_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value))
1008        : __base_(__p)
1009    { }
1010
1011    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1012        _And<
1013            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
1014            _BothImplicitlyConvertible<const pair<_Up1, _Up2>&> // explicit check
1015        >::value
1016    , int> = 0>
1017    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1018    tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
1019        : __base_(allocator_arg_t(), __a, __p)
1020    { }
1021
1022    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1023        _And<
1024            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
1025            _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> > // explicit check
1026        >::value
1027    , int> = 0>
1028    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1029    explicit tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
1030        : __base_(allocator_arg_t(), __a, __p)
1031    { }
1032
1033#if _LIBCPP_STD_VER >= 23
1034    // tuple(pair<U1, U2>&) constructors (including allocator_arg_t variants)
1035
1036    template <class _U1, class _U2, enable_if_t<
1037        _EnableCtorFromPair<pair<_U1, _U2>&>::value>* = nullptr>
1038    _LIBCPP_HIDE_FROM_ABI constexpr
1039        explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
1040    tuple(pair<_U1, _U2>& __p) : __base_(__p) {}
1041
1042    template <class _Alloc, class _U1, class _U2, enable_if_t<
1043        _EnableCtorFromPair<std::pair<_U1, _U2>&>::value>* = nullptr>
1044    _LIBCPP_HIDE_FROM_ABI constexpr
1045        explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
1046    tuple(allocator_arg_t, const _Alloc& __alloc, pair<_U1, _U2>& __p) : __base_(allocator_arg_t(), __alloc, __p) {}
1047#endif
1048
1049    // tuple(pair<U1, U2>&&) constructors (including allocator_arg_t variants)
1050
1051    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1052        _And<
1053            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1054            _BothImplicitlyConvertible<pair<_Up1, _Up2>&&> // explicit check
1055        >::value
1056    , int> = 0>
1057    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1058    tuple(pair<_Up1, _Up2>&& __p)
1059        _NOEXCEPT_((_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value))
1060        : __base_(_VSTD::move(__p))
1061    { }
1062
1063    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1064        _And<
1065            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1066            _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> > // explicit check
1067        >::value
1068    , int> = 0>
1069    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1070    explicit tuple(pair<_Up1, _Up2>&& __p)
1071        _NOEXCEPT_((_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value))
1072        : __base_(_VSTD::move(__p))
1073    { }
1074
1075    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1076        _And<
1077            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1078            _BothImplicitlyConvertible<pair<_Up1, _Up2>&&> // explicit check
1079        >::value
1080    , int> = 0>
1081    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1082    tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
1083        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
1084    { }
1085
1086    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1087        _And<
1088            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1089            _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> > // explicit check
1090        >::value
1091    , int> = 0>
1092    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1093    explicit tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
1094        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
1095    { }
1096
1097#if _LIBCPP_STD_VER >= 23
1098    // tuple(const pair<U1, U2>&&) constructors (including allocator_arg_t variants)
1099
1100    template <class _U1, class _U2, enable_if_t<
1101        _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
1102    _LIBCPP_HIDE_FROM_ABI constexpr
1103        explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
1104    tuple(const pair<_U1, _U2>&& __p) : __base_(std::move(__p)) {}
1105
1106    template <class _Alloc, class _U1, class _U2, enable_if_t<
1107        _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
1108    _LIBCPP_HIDE_FROM_ABI constexpr
1109        explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
1110    tuple(allocator_arg_t, const _Alloc& __alloc, const pair<_U1, _U2>&& __p)
1111        : __base_(allocator_arg_t(), __alloc, std::move(__p)) {}
1112#endif // _LIBCPP_STD_VER >= 23
1113
1114    // [tuple.assign]
1115    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1116    tuple& operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple)
1117        _NOEXCEPT_((_And<is_nothrow_copy_assignable<_Tp>...>::value))
1118    {
1119        _VSTD::__memberwise_copy_assign(*this, __tuple,
1120            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1121        return *this;
1122    }
1123
1124#if _LIBCPP_STD_VER >= 23
1125    _LIBCPP_HIDE_FROM_ABI constexpr
1126    const tuple& operator=(tuple const& __tuple) const
1127      requires (_And<is_copy_assignable<const _Tp>...>::value) {
1128        std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
1129        return *this;
1130    }
1131
1132    _LIBCPP_HIDE_FROM_ABI constexpr
1133    const tuple& operator=(tuple&& __tuple) const
1134      requires (_And<is_assignable<const _Tp&, _Tp>...>::value) {
1135        std::__memberwise_forward_assign(*this,
1136                                         std::move(__tuple),
1137                                         __tuple_types<_Tp...>(),
1138                                         typename __make_tuple_indices<sizeof...(_Tp)>::type());
1139        return *this;
1140    }
1141#endif // _LIBCPP_STD_VER >= 23
1142
1143    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1144    tuple& operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple)
1145        _NOEXCEPT_((_And<is_nothrow_move_assignable<_Tp>...>::value))
1146    {
1147        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
1148            __tuple_types<_Tp...>(),
1149            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1150        return *this;
1151    }
1152
1153    template<class... _Up, __enable_if_t<
1154        _And<
1155            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
1156            is_assignable<_Tp&, _Up const&>...
1157        >::value
1158    ,int> = 0>
1159    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1160    tuple& operator=(tuple<_Up...> const& __tuple)
1161        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
1162    {
1163        _VSTD::__memberwise_copy_assign(*this, __tuple,
1164            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1165        return *this;
1166    }
1167
1168    template<class... _Up, __enable_if_t<
1169        _And<
1170            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
1171            is_assignable<_Tp&, _Up>...
1172        >::value
1173    ,int> = 0>
1174    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1175    tuple& operator=(tuple<_Up...>&& __tuple)
1176        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
1177    {
1178        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
1179            __tuple_types<_Up...>(),
1180            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1181        return *this;
1182    }
1183
1184
1185#if _LIBCPP_STD_VER >= 23
1186    template <class... _UTypes, enable_if_t<
1187        _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
1188             is_assignable<const _Tp&, const _UTypes&>...>::value>* = nullptr>
1189    _LIBCPP_HIDE_FROM_ABI constexpr
1190    const tuple& operator=(const tuple<_UTypes...>& __u) const {
1191        std::__memberwise_copy_assign(*this,
1192                                      __u,
1193                                      typename __make_tuple_indices<sizeof...(_Tp)>::type());
1194        return *this;
1195    }
1196
1197    template <class... _UTypes, enable_if_t<
1198        _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
1199             is_assignable<const _Tp&, _UTypes>...>::value>* = nullptr>
1200    _LIBCPP_HIDE_FROM_ABI constexpr
1201    const tuple& operator=(tuple<_UTypes...>&& __u) const {
1202        std::__memberwise_forward_assign(*this,
1203                                         __u,
1204                                         __tuple_types<_UTypes...>(),
1205                                         typename __make_tuple_indices<sizeof...(_Tp)>::type());
1206        return *this;
1207    }
1208#endif // _LIBCPP_STD_VER >= 23
1209
1210    template <template<class...> class _Pred, bool _Const,
1211              class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
1212    struct _AssignPredicateFromPair : false_type {};
1213
1214    template <template<class...> class _Pred, bool _Const,
1215              class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
1216    struct _AssignPredicateFromPair<_Pred, _Const, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > :
1217        _And<_Pred<__maybe_const<_Const, _Tp1>&, __copy_cvref_t<_Pair, _Up1> >,
1218             _Pred<__maybe_const<_Const, _Tp2>&, __copy_cvref_t<_Pair, _Up2> >
1219            > {};
1220
1221    template <bool _Const, class _Pair>
1222    struct _EnableAssignFromPair : _AssignPredicateFromPair<is_assignable, _Const, _Pair> {};
1223
1224    template <bool _Const, class _Pair>
1225    struct _NothrowAssignFromPair : _AssignPredicateFromPair<is_nothrow_assignable, _Const, _Pair> {};
1226
1227#if _LIBCPP_STD_VER >= 23
1228    template <class _U1, class _U2, enable_if_t<
1229        _EnableAssignFromPair<true, const pair<_U1, _U2>&>::value>* = nullptr>
1230    _LIBCPP_HIDE_FROM_ABI constexpr
1231    const tuple& operator=(const pair<_U1, _U2>& __pair) const
1232      noexcept(_NothrowAssignFromPair<true, const pair<_U1, _U2>&>::value) {
1233        std::get<0>(*this) = __pair.first;
1234        std::get<1>(*this) = __pair.second;
1235        return *this;
1236    }
1237
1238    template <class _U1, class _U2, enable_if_t<
1239        _EnableAssignFromPair<true, pair<_U1, _U2>&&>::value>* = nullptr>
1240    _LIBCPP_HIDE_FROM_ABI constexpr
1241    const tuple& operator=(pair<_U1, _U2>&& __pair) const
1242      noexcept(_NothrowAssignFromPair<true, pair<_U1, _U2>&&>::value) {
1243        std::get<0>(*this) = std::move(__pair.first);
1244        std::get<1>(*this) = std::move(__pair.second);
1245        return *this;
1246    }
1247#endif // _LIBCPP_STD_VER >= 23
1248
1249    template<class _Up1, class _Up2, __enable_if_t<
1250        _EnableAssignFromPair<false, pair<_Up1, _Up2> const&>::value
1251    ,int> = 0>
1252    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1253    tuple& operator=(pair<_Up1, _Up2> const& __pair)
1254        _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2> const&>::value))
1255    {
1256        _VSTD::get<0>(*this) = __pair.first;
1257        _VSTD::get<1>(*this) = __pair.second;
1258        return *this;
1259    }
1260
1261    template<class _Up1, class _Up2, __enable_if_t<
1262        _EnableAssignFromPair<false, pair<_Up1, _Up2>&&>::value
1263    ,int> = 0>
1264    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1265    tuple& operator=(pair<_Up1, _Up2>&& __pair)
1266        _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2>&&>::value))
1267    {
1268        _VSTD::get<0>(*this) = _VSTD::forward<_Up1>(__pair.first);
1269        _VSTD::get<1>(*this) = _VSTD::forward<_Up2>(__pair.second);
1270        return *this;
1271    }
1272
1273    // EXTENSION
1274    template<class _Up, size_t _Np, class = __enable_if_t<
1275        _And<
1276            _BoolConstant<_Np == sizeof...(_Tp)>,
1277            is_assignable<_Tp&, _Up const&>...
1278        >::value
1279    > >
1280    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1281    tuple& operator=(array<_Up, _Np> const& __array)
1282        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
1283    {
1284        _VSTD::__memberwise_copy_assign(*this, __array,
1285            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1286        return *this;
1287    }
1288
1289    // EXTENSION
1290    template<class _Up, size_t _Np, class = void, class = __enable_if_t<
1291        _And<
1292            _BoolConstant<_Np == sizeof...(_Tp)>,
1293            is_assignable<_Tp&, _Up>...
1294        >::value
1295    > >
1296    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1297    tuple& operator=(array<_Up, _Np>&& __array)
1298        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
1299    {
1300        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__array),
1301            __tuple_types<_If<true, _Up, _Tp>...>(),
1302            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1303        return *this;
1304    }
1305
1306    // [tuple.swap]
1307    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1308    void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
1309        {__base_.swap(__t.__base_);}
1310
1311#if _LIBCPP_STD_VER >= 23
1312    _LIBCPP_HIDE_FROM_ABI constexpr
1313    void swap(const tuple& __t) const noexcept(__all<is_nothrow_swappable_v<const _Tp&>...>::value) {
1314        __base_.swap(__t.__base_);
1315    }
1316#endif // _LIBCPP_STD_VER >= 23
1317};
1318
1319template <>
1320class _LIBCPP_TEMPLATE_VIS tuple<>
1321{
1322public:
1323    constexpr tuple() _NOEXCEPT = default;
1324    template <class _Alloc>
1325    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1326        tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
1327    template <class _Alloc>
1328    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1329        tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
1330    template <class _Up>
1331    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1332        tuple(array<_Up, 0>) _NOEXCEPT {}
1333    template <class _Alloc, class _Up>
1334    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1335        tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
1336    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1337    void swap(tuple&) _NOEXCEPT {}
1338#if _LIBCPP_STD_VER >= 23
1339    _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple&) const noexcept {}
1340#endif
1341};
1342
1343#if _LIBCPP_STD_VER >= 23
1344template <class... _TTypes, class... _UTypes, template<class> class _TQual, template<class> class _UQual>
1345    requires requires { typename tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>; }
1346struct basic_common_reference<tuple<_TTypes...>, tuple<_UTypes...>, _TQual, _UQual> {
1347    using type = tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>;
1348};
1349
1350template <class... _TTypes, class... _UTypes>
1351    requires requires { typename tuple<common_type_t<_TTypes, _UTypes>...>; }
1352struct common_type<tuple<_TTypes...>, tuple<_UTypes...>> {
1353    using type = tuple<common_type_t<_TTypes, _UTypes>...>;
1354};
1355#endif // _LIBCPP_STD_VER >= 23
1356
1357#if _LIBCPP_STD_VER >= 17
1358template <class ..._Tp>
1359tuple(_Tp...) -> tuple<_Tp...>;
1360template <class _Tp1, class _Tp2>
1361tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1362template <class _Alloc, class ..._Tp>
1363tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;
1364template <class _Alloc, class _Tp1, class _Tp2>
1365tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1366template <class _Alloc, class ..._Tp>
1367tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;
1368#endif
1369
1370template <class ..._Tp>
1371inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1372__enable_if_t<__all<__is_swappable<_Tp>::value...>::value, void>
1373swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
1374                 _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
1375    {__t.swap(__u);}
1376
1377#if _LIBCPP_STD_VER >= 23
1378template <class... _Tp>
1379_LIBCPP_HIDE_FROM_ABI constexpr
1380enable_if_t<__all<is_swappable_v<const _Tp>...>::value, void>
1381swap(const tuple<_Tp...>& __lhs, const tuple<_Tp...>& __rhs)
1382        noexcept(__all<is_nothrow_swappable_v<const _Tp>...>::value) {
1383    __lhs.swap(__rhs);
1384}
1385#endif
1386
1387// get
1388
1389template <size_t _Ip, class ..._Tp>
1390inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1391typename tuple_element<_Ip, tuple<_Tp...> >::type&
1392get(tuple<_Tp...>& __t) _NOEXCEPT
1393{
1394    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1395    return static_cast<__tuple_leaf<_Ip, type>&>(__t.__base_).get();
1396}
1397
1398template <size_t _Ip, class ..._Tp>
1399inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1400const typename tuple_element<_Ip, tuple<_Tp...> >::type&
1401get(const tuple<_Tp...>& __t) _NOEXCEPT
1402{
1403    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1404    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.__base_).get();
1405}
1406
1407template <size_t _Ip, class ..._Tp>
1408inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1409typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1410get(tuple<_Tp...>&& __t) _NOEXCEPT
1411{
1412    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1413    return static_cast<type&&>(
1414             static_cast<__tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1415}
1416
1417template <size_t _Ip, class ..._Tp>
1418inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1419const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1420get(const tuple<_Tp...>&& __t) _NOEXCEPT
1421{
1422    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1423    return static_cast<const type&&>(
1424             static_cast<const __tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1425}
1426
1427#if _LIBCPP_STD_VER >= 14
1428
1429namespace __find_detail {
1430
1431static constexpr size_t __not_found = static_cast<size_t>(-1);
1432static constexpr size_t __ambiguous = __not_found - 1;
1433
1434inline _LIBCPP_INLINE_VISIBILITY
1435constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) {
1436    return !__matches ? __res :
1437        (__res == __not_found ? __curr_i : __ambiguous);
1438}
1439
1440template <size_t _Nx>
1441inline _LIBCPP_INLINE_VISIBILITY
1442constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {
1443  return __i == _Nx ? __not_found :
1444      __find_detail::__find_idx_return(__i, __find_detail::__find_idx(__i + 1, __matches), __matches[__i]);
1445}
1446
1447template <class _T1, class ..._Args>
1448struct __find_exactly_one_checked {
1449    static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...};
1450    static constexpr size_t value = __find_detail::__find_idx(0, __matches);
1451    static_assert(value != __not_found, "type not found in type list" );
1452    static_assert(value != __ambiguous, "type occurs more than once in type list");
1453};
1454
1455template <class _T1>
1456struct __find_exactly_one_checked<_T1> {
1457    static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");
1458};
1459
1460} // namespace __find_detail
1461
1462template <typename _T1, typename... _Args>
1463struct __find_exactly_one_t
1464    : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {
1465};
1466
1467template <class _T1, class... _Args>
1468inline _LIBCPP_INLINE_VISIBILITY
1469constexpr _T1& get(tuple<_Args...>& __tup) noexcept
1470{
1471    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1472}
1473
1474template <class _T1, class... _Args>
1475inline _LIBCPP_INLINE_VISIBILITY
1476constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
1477{
1478    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1479}
1480
1481template <class _T1, class... _Args>
1482inline _LIBCPP_INLINE_VISIBILITY
1483constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
1484{
1485    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
1486}
1487
1488template <class _T1, class... _Args>
1489inline _LIBCPP_INLINE_VISIBILITY
1490constexpr _T1 const&& get(tuple<_Args...> const&& __tup) noexcept
1491{
1492    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
1493}
1494
1495#endif
1496
1497// tie
1498
1499template <class ..._Tp>
1500inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1501tuple<_Tp&...>
1502tie(_Tp&... __t) _NOEXCEPT
1503{
1504    return tuple<_Tp&...>(__t...);
1505}
1506
1507template <class _Up>
1508struct __ignore_t
1509{
1510    template <class _Tp>
1511    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1512    const __ignore_t& operator=(_Tp&&) const {return *this;}
1513};
1514
1515#  if _LIBCPP_STD_VER >= 17
1516inline constexpr __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>();
1517#  else
1518namespace {
1519  constexpr __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>();
1520} // namespace
1521#  endif
1522
1523template <class... _Tp>
1524inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1525tuple<typename __unwrap_ref_decay<_Tp>::type...>
1526make_tuple(_Tp&&... __t)
1527{
1528    return tuple<typename __unwrap_ref_decay<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
1529}
1530
1531template <class... _Tp>
1532inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1533tuple<_Tp&&...>
1534forward_as_tuple(_Tp&&... __t) _NOEXCEPT
1535{
1536    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
1537}
1538
1539template <size_t _Ip>
1540struct __tuple_equal
1541{
1542    template <class _Tp, class _Up>
1543    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1544    bool operator()(const _Tp& __x, const _Up& __y)
1545    {
1546        return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
1547    }
1548};
1549
1550template <>
1551struct __tuple_equal<0>
1552{
1553    template <class _Tp, class _Up>
1554    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1555    bool operator()(const _Tp&, const _Up&)
1556    {
1557        return true;
1558    }
1559};
1560
1561template <class ..._Tp, class ..._Up>
1562inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1563bool
1564operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1565{
1566    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1567    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
1568}
1569
1570#if _LIBCPP_STD_VER >= 20
1571
1572// operator<=>
1573
1574template <class ..._Tp, class ..._Up, size_t ..._Is>
1575_LIBCPP_HIDE_FROM_ABI constexpr
1576auto
1577__tuple_compare_three_way(const tuple<_Tp...>& __x, const tuple<_Up...>& __y, index_sequence<_Is...>) {
1578    common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...> __result = strong_ordering::equal;
1579    static_cast<void>(((__result = _VSTD::__synth_three_way(_VSTD::get<_Is>(__x), _VSTD::get<_Is>(__y)), __result != 0) || ...));
1580    return __result;
1581}
1582
1583template <class ..._Tp, class ..._Up>
1584requires (sizeof...(_Tp) == sizeof...(_Up))
1585_LIBCPP_HIDE_FROM_ABI constexpr
1586common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...>
1587operator<=>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1588{
1589    return _VSTD::__tuple_compare_three_way(__x, __y, index_sequence_for<_Tp...>{});
1590}
1591
1592#else // _LIBCPP_STD_VER >= 20
1593
1594template <class ..._Tp, class ..._Up>
1595inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1596bool
1597operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1598{
1599    return !(__x == __y);
1600}
1601
1602template <size_t _Ip>
1603struct __tuple_less
1604{
1605    template <class _Tp, class _Up>
1606    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1607    bool operator()(const _Tp& __x, const _Up& __y)
1608    {
1609        const size_t __idx = tuple_size<_Tp>::value - _Ip;
1610        if (_VSTD::get<__idx>(__x) < _VSTD::get<__idx>(__y))
1611            return true;
1612        if (_VSTD::get<__idx>(__y) < _VSTD::get<__idx>(__x))
1613            return false;
1614        return __tuple_less<_Ip-1>()(__x, __y);
1615    }
1616};
1617
1618template <>
1619struct __tuple_less<0>
1620{
1621    template <class _Tp, class _Up>
1622    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1623    bool operator()(const _Tp&, const _Up&)
1624    {
1625        return false;
1626    }
1627};
1628
1629template <class ..._Tp, class ..._Up>
1630inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1631bool
1632operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1633{
1634    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1635    return __tuple_less<sizeof...(_Tp)>()(__x, __y);
1636}
1637
1638template <class ..._Tp, class ..._Up>
1639inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1640bool
1641operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1642{
1643    return __y < __x;
1644}
1645
1646template <class ..._Tp, class ..._Up>
1647inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1648bool
1649operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1650{
1651    return !(__x < __y);
1652}
1653
1654template <class ..._Tp, class ..._Up>
1655inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1656bool
1657operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1658{
1659    return !(__y < __x);
1660}
1661
1662#endif // _LIBCPP_STD_VER >= 20
1663
1664// tuple_cat
1665
1666template <class _Tp, class _Up> struct __tuple_cat_type;
1667
1668template <class ..._Ttypes, class ..._Utypes>
1669struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
1670{
1671    typedef _LIBCPP_NODEBUG tuple<_Ttypes..., _Utypes...> type;
1672};
1673
1674template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
1675struct __tuple_cat_return_1
1676{
1677};
1678
1679template <class ..._Types, class _Tuple0>
1680struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
1681{
1682  using type _LIBCPP_NODEBUG = typename __tuple_cat_type<
1683      tuple<_Types...>,
1684      typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type
1685    >::type;
1686};
1687
1688template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
1689struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
1690    : public __tuple_cat_return_1<
1691                 typename __tuple_cat_type<
1692                     tuple<_Types...>,
1693                     typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type
1694                 >::type,
1695                 __tuple_like_ext<__libcpp_remove_reference_t<_Tuple1> >::value,
1696                 _Tuple1, _Tuples...>
1697{
1698};
1699
1700template <class ..._Tuples> struct __tuple_cat_return;
1701
1702template <class _Tuple0, class ..._Tuples>
1703struct __tuple_cat_return<_Tuple0, _Tuples...>
1704    : public __tuple_cat_return_1<tuple<>,
1705         __tuple_like_ext<__libcpp_remove_reference_t<_Tuple0> >::value, _Tuple0,
1706                                                                     _Tuples...>
1707{
1708};
1709
1710template <>
1711struct __tuple_cat_return<>
1712{
1713    typedef _LIBCPP_NODEBUG tuple<> type;
1714};
1715
1716inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1717tuple<>
1718tuple_cat()
1719{
1720    return tuple<>();
1721}
1722
1723template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1724struct __tuple_cat_return_ref_imp;
1725
1726template <class ..._Types, size_t ..._I0, class _Tuple0>
1727struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1728{
1729    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1730    typedef tuple<_Types..., __apply_cv_t<_Tuple0, typename tuple_element<_I0, _T0>::type>&&...> type;
1731};
1732
1733template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1734struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1735                                  _Tuple0, _Tuple1, _Tuples...>
1736    : public __tuple_cat_return_ref_imp<
1737         tuple<_Types..., __apply_cv_t<_Tuple0,
1738                                       typename tuple_element<_I0, __libcpp_remove_reference_t<_Tuple0>>::type>&&...>,
1739         typename __make_tuple_indices<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>::type,
1740         _Tuple1, _Tuples...>
1741{
1742};
1743
1744template <class _Tuple0, class ..._Tuples>
1745struct __tuple_cat_return_ref
1746    : public __tuple_cat_return_ref_imp<tuple<>,
1747               typename __make_tuple_indices<
1748                        tuple_size<__libcpp_remove_reference_t<_Tuple0> >::value
1749               >::type, _Tuple0, _Tuples...>
1750{
1751};
1752
1753template <class _Types, class _I0, class _J0>
1754struct __tuple_cat;
1755
1756template <class ..._Types, size_t ..._I0, size_t ..._J0>
1757struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1758{
1759    template <class _Tuple0>
1760    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1761    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1762    operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1763    {
1764        (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1765        return _VSTD::forward_as_tuple(
1766            _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1767            _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1768    }
1769
1770    template <class _Tuple0, class _Tuple1, class ..._Tuples>
1771    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1772    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1773    operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1774    {
1775        (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1776        typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1777        typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple1> _T1;
1778        return __tuple_cat<tuple<_Types..., __apply_cv_t<_Tuple0, typename tuple_element<_J0, _T0>::type>&&...>,
1779                           typename __make_tuple_indices<sizeof...(_Types) + tuple_size<_T0>::value>::type,
1780                           typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
1781            _VSTD::forward_as_tuple(
1782                _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1783                _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...),
1784            _VSTD::forward<_Tuple1>(__t1), _VSTD::forward<_Tuples>(__tpls)...);
1785    }
1786};
1787
1788template <class _Tuple0, class... _Tuples>
1789inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1790typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1791tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1792{
1793    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1794    return __tuple_cat<tuple<>, __tuple_indices<>,
1795                  typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1796                  (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1797                                            _VSTD::forward<_Tuples>(__tpls)...);
1798}
1799
1800template <class ..._Tp, class _Alloc>
1801struct _LIBCPP_TEMPLATE_VIS uses_allocator<tuple<_Tp...>, _Alloc>
1802    : true_type {};
1803
1804template <class _T1, class _T2>
1805template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1806inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1807pair<_T1, _T2>::pair(piecewise_construct_t,
1808                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1809                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1810    :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
1811      second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
1812{
1813}
1814
1815#if _LIBCPP_STD_VER >= 17
1816template <class _Tp>
1817inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
1818
1819#define _LIBCPP_NOEXCEPT_RETURN(...) noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
1820
1821template <class _Fn, class _Tuple, size_t ..._Id>
1822inline _LIBCPP_INLINE_VISIBILITY
1823constexpr decltype(auto) __apply_tuple_impl(_Fn && __f, _Tuple && __t,
1824                                            __tuple_indices<_Id...>)
1825_LIBCPP_NOEXCEPT_RETURN(
1826    _VSTD::__invoke(
1827        _VSTD::forward<_Fn>(__f),
1828        _VSTD::get<_Id>(_VSTD::forward<_Tuple>(__t))...)
1829)
1830
1831template <class _Fn, class _Tuple>
1832inline _LIBCPP_INLINE_VISIBILITY
1833constexpr decltype(auto) apply(_Fn && __f, _Tuple && __t)
1834_LIBCPP_NOEXCEPT_RETURN(
1835    _VSTD::__apply_tuple_impl(
1836        _VSTD::forward<_Fn>(__f), _VSTD::forward<_Tuple>(__t),
1837        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
1838)
1839
1840template <class _Tp, class _Tuple, size_t... _Idx>
1841inline _LIBCPP_INLINE_VISIBILITY
1842constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>)
1843_LIBCPP_NOEXCEPT_RETURN(
1844    _Tp(_VSTD::get<_Idx>(_VSTD::forward<_Tuple>(__t))...)
1845)
1846
1847template <class _Tp, class _Tuple>
1848inline _LIBCPP_INLINE_VISIBILITY
1849constexpr _Tp make_from_tuple(_Tuple&& __t)
1850_LIBCPP_NOEXCEPT_RETURN(
1851    _VSTD::__make_from_tuple_impl<_Tp>(_VSTD::forward<_Tuple>(__t),
1852        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
1853)
1854
1855#undef _LIBCPP_NOEXCEPT_RETURN
1856
1857#endif // _LIBCPP_STD_VER >= 17
1858
1859#endif // !defined(_LIBCPP_CXX03_LANG)
1860
1861_LIBCPP_END_NAMESPACE_STD
1862
1863_LIBCPP_POP_MACROS
1864
1865#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1866#  include <exception>
1867#  include <iosfwd>
1868#  include <new>
1869#  include <type_traits>
1870#  include <typeinfo>
1871#  include <utility>
1872#endif
1873
1874#endif // _LIBCPP_TUPLE
1875