xref: /freebsd/contrib/llvm-project/libcxx/include/tuple (revision bdd1243df58e60e85101c09001d9812a789b6bc4)
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 <__functional/unwrap_ref.h>
210#include <__fwd/array.h>
211#include <__memory/allocator_arg_t.h>
212#include <__memory/uses_allocator.h>
213#include <__type_traits/apply_cv.h>
214#include <__type_traits/common_reference.h>
215#include <__type_traits/common_type.h>
216#include <__type_traits/conditional.h>
217#include <__type_traits/conjunction.h>
218#include <__type_traits/copy_cvref.h>
219#include <__type_traits/disjunction.h>
220#include <__type_traits/is_arithmetic.h>
221#include <__type_traits/is_assignable.h>
222#include <__type_traits/is_constructible.h>
223#include <__type_traits/is_convertible.h>
224#include <__type_traits/is_copy_assignable.h>
225#include <__type_traits/is_copy_constructible.h>
226#include <__type_traits/is_default_constructible.h>
227#include <__type_traits/is_empty.h>
228#include <__type_traits/is_final.h>
229#include <__type_traits/is_implicitly_default_constructible.h>
230#include <__type_traits/is_move_assignable.h>
231#include <__type_traits/is_move_constructible.h>
232#include <__type_traits/is_nothrow_assignable.h>
233#include <__type_traits/is_nothrow_constructible.h>
234#include <__type_traits/is_nothrow_copy_assignable.h>
235#include <__type_traits/is_nothrow_copy_constructible.h>
236#include <__type_traits/is_nothrow_default_constructible.h>
237#include <__type_traits/is_nothrow_move_assignable.h>
238#include <__type_traits/is_reference.h>
239#include <__type_traits/is_same.h>
240#include <__type_traits/is_swappable.h>
241#include <__type_traits/lazy.h>
242#include <__type_traits/maybe_const.h>
243#include <__type_traits/nat.h>
244#include <__type_traits/negation.h>
245#include <__type_traits/remove_cvref.h>
246#include <__type_traits/remove_reference.h>
247#include <__utility/forward.h>
248#include <__utility/integer_sequence.h>
249#include <__utility/move.h>
250#include <__utility/pair.h>
251#include <__utility/piecewise_construct.h>
252#include <__utility/swap.h>
253#include <cstddef>
254#include <version>
255
256// standard-mandated includes
257
258// [tuple.syn]
259#include <compare>
260
261#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
262#  pragma GCC system_header
263#endif
264
265_LIBCPP_BEGIN_NAMESPACE_STD
266
267#ifndef _LIBCPP_CXX03_LANG
268
269
270// __tuple_leaf
271
272template <size_t _Ip, class _Hp,
273          bool=is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value
274         >
275class __tuple_leaf;
276
277template <size_t _Ip, class _Hp, bool _Ep>
278inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
279void swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)
280    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value)
281{
282    swap(__x.get(), __y.get());
283}
284
285template <size_t _Ip, class _Hp, bool _Ep>
286_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
287void swap(const __tuple_leaf<_Ip, _Hp, _Ep>& __x, const __tuple_leaf<_Ip, _Hp, _Ep>& __y)
288     _NOEXCEPT_(__is_nothrow_swappable<const _Hp>::value) {
289  swap(__x.get(), __y.get());
290}
291
292template <size_t _Ip, class _Hp, bool>
293class __tuple_leaf
294{
295    _Hp __value_;
296
297    template <class _Tp>
298    static constexpr bool __can_bind_reference() {
299#if __has_keyword(__reference_binds_to_temporary)
300      return !__reference_binds_to_temporary(_Hp, _Tp);
301#else
302      return true;
303#endif
304    }
305
306    _LIBCPP_CONSTEXPR_SINCE_CXX14
307    __tuple_leaf& operator=(const __tuple_leaf&);
308public:
309    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
310             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : __value_()
311       {static_assert(!is_reference<_Hp>::value,
312              "Attempted to default construct a reference element in a tuple");}
313
314    template <class _Alloc>
315        _LIBCPP_INLINE_VISIBILITY constexpr
316        __tuple_leaf(integral_constant<int, 0>, const _Alloc&)
317            : __value_()
318        {static_assert(!is_reference<_Hp>::value,
319              "Attempted to default construct a reference element in a tuple");}
320
321    template <class _Alloc>
322        _LIBCPP_INLINE_VISIBILITY constexpr
323        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
324            : __value_(allocator_arg_t(), __a)
325        {static_assert(!is_reference<_Hp>::value,
326              "Attempted to default construct a reference element in a tuple");}
327
328    template <class _Alloc>
329        _LIBCPP_INLINE_VISIBILITY constexpr
330        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
331            : __value_(__a)
332        {static_assert(!is_reference<_Hp>::value,
333              "Attempted to default construct a reference element in a tuple");}
334
335    template <class _Tp,
336              class = __enable_if_t<
337                  _And<
338                      _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>,
339                      is_constructible<_Hp, _Tp>
340                    >::value
341                >
342            >
343        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
344        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
345            : __value_(_VSTD::forward<_Tp>(__t))
346        {static_assert(__can_bind_reference<_Tp&&>(),
347       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
348
349    template <class _Tp, class _Alloc>
350        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
351        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
352            : __value_(_VSTD::forward<_Tp>(__t))
353        {static_assert(__can_bind_reference<_Tp&&>(),
354       "Attempted construction of reference element binds to a temporary whose lifetime has ended");}
355
356    template <class _Tp, class _Alloc>
357        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
358        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
359            : __value_(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t))
360        {static_assert(!is_reference<_Hp>::value,
361            "Attempted to uses-allocator construct a reference element in a tuple");}
362
363    template <class _Tp, class _Alloc>
364        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
365        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
366            : __value_(_VSTD::forward<_Tp>(__t), __a)
367        {static_assert(!is_reference<_Hp>::value,
368           "Attempted to uses-allocator construct a reference element in a tuple");}
369
370    __tuple_leaf(const __tuple_leaf& __t) = default;
371    __tuple_leaf(__tuple_leaf&& __t) = default;
372
373    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
374    int swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
375    {
376        _VSTD::swap(*this, __t);
377        return 0;
378    }
379
380    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
381    int swap(const __tuple_leaf& __t) const _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {
382        _VSTD::swap(*this, __t);
383        return 0;
384    }
385
386    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14       _Hp& get()       _NOEXCEPT {return __value_;}
387    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {return __value_;}
388};
389
390template <size_t _Ip, class _Hp>
391class __tuple_leaf<_Ip, _Hp, true>
392    : private _Hp
393{
394    _LIBCPP_CONSTEXPR_SINCE_CXX14
395    __tuple_leaf& operator=(const __tuple_leaf&);
396public:
397    _LIBCPP_INLINE_VISIBILITY constexpr __tuple_leaf()
398             _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
399
400    template <class _Alloc>
401        _LIBCPP_INLINE_VISIBILITY constexpr
402        __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}
403
404    template <class _Alloc>
405        _LIBCPP_INLINE_VISIBILITY constexpr
406        __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)
407            : _Hp(allocator_arg_t(), __a) {}
408
409    template <class _Alloc>
410        _LIBCPP_INLINE_VISIBILITY constexpr
411        __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
412            : _Hp(__a) {}
413
414    template <class _Tp,
415              class = __enable_if_t<
416                  _And<
417                    _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>,
418                    is_constructible<_Hp, _Tp>
419                  >::value
420                >
421            >
422        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
423        explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
424            : _Hp(_VSTD::forward<_Tp>(__t)) {}
425
426    template <class _Tp, class _Alloc>
427        _LIBCPP_INLINE_VISIBILITY constexpr
428        explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)
429            : _Hp(_VSTD::forward<_Tp>(__t)) {}
430
431    template <class _Tp, class _Alloc>
432        _LIBCPP_INLINE_VISIBILITY constexpr
433        explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)
434            : _Hp(allocator_arg_t(), __a, _VSTD::forward<_Tp>(__t)) {}
435
436    template <class _Tp, class _Alloc>
437        _LIBCPP_INLINE_VISIBILITY constexpr
438        explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)
439            : _Hp(_VSTD::forward<_Tp>(__t), __a) {}
440
441    __tuple_leaf(__tuple_leaf const &) = default;
442    __tuple_leaf(__tuple_leaf &&) = default;
443
444    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
445    int
446    swap(__tuple_leaf& __t) _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value)
447    {
448        _VSTD::swap(*this, __t);
449        return 0;
450    }
451
452    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
453    int swap(const __tuple_leaf& __rhs) const _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {
454        _VSTD::swap(*this, __rhs);
455        return 0;
456    }
457
458    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14       _Hp& get()       _NOEXCEPT {return static_cast<_Hp&>(*this);}
459    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {return static_cast<const _Hp&>(*this);}
460};
461
462template <class ..._Tp>
463_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
464void __swallow(_Tp&&...) _NOEXCEPT {}
465
466template <class _Tp>
467struct __all_default_constructible;
468
469template <class ..._Tp>
470struct __all_default_constructible<__tuple_types<_Tp...>>
471    : __all<is_default_constructible<_Tp>::value...>
472{ };
473
474// __tuple_impl
475
476template<class _Indx, class ..._Tp> struct __tuple_impl;
477
478template<size_t ..._Indx, class ..._Tp>
479struct _LIBCPP_DECLSPEC_EMPTY_BASES __tuple_impl<__tuple_indices<_Indx...>, _Tp...>
480    : public __tuple_leaf<_Indx, _Tp>...
481{
482    _LIBCPP_INLINE_VISIBILITY
483    constexpr __tuple_impl()
484        _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
485
486    template <size_t ..._Uf, class ..._Tf,
487              size_t ..._Ul, class ..._Tl, class ..._Up>
488        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
489        explicit
490        __tuple_impl(__tuple_indices<_Uf...>, __tuple_types<_Tf...>,
491                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
492                     _Up&&... __u)
493                     _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&
494                                 __all<is_nothrow_default_constructible<_Tl>::value...>::value)) :
495            __tuple_leaf<_Uf, _Tf>(_VSTD::forward<_Up>(__u))...,
496            __tuple_leaf<_Ul, _Tl>()...
497            {}
498
499    template <class _Alloc, size_t ..._Uf, class ..._Tf,
500              size_t ..._Ul, class ..._Tl, class ..._Up>
501        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
502        explicit
503        __tuple_impl(allocator_arg_t, const _Alloc& __a,
504                     __tuple_indices<_Uf...>, __tuple_types<_Tf...>,
505                     __tuple_indices<_Ul...>, __tuple_types<_Tl...>,
506                     _Up&&... __u) :
507            __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a,
508            _VSTD::forward<_Up>(__u))...,
509            __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)...
510            {}
511
512    template <class _Tuple,
513              class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value>
514             >
515        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
516        __tuple_impl(_Tuple&& __t) _NOEXCEPT_((__all<is_nothrow_constructible<_Tp, typename tuple_element<_Indx,
517                                       typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))
518            : __tuple_leaf<_Indx, _Tp>(_VSTD::forward<typename tuple_element<_Indx,
519                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
520            {}
521
522    template <class _Alloc, class _Tuple,
523              class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value>
524             >
525        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
526        __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)
527            : __tuple_leaf<_Indx, _Tp>(__uses_alloc_ctor<_Tp, _Alloc, typename tuple_element<_Indx,
528                                       typename __make_tuple_types<_Tuple>::type>::type>(), __a,
529                                       _VSTD::forward<typename tuple_element<_Indx,
530                                       typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<_Indx>(__t)))...
531            {}
532
533    __tuple_impl(const __tuple_impl&) = default;
534    __tuple_impl(__tuple_impl&&) = default;
535
536    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
537    void swap(__tuple_impl& __t)
538        _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
539    {
540        _VSTD::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);
541    }
542
543    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
544    void swap(const __tuple_impl& __t) const
545        _NOEXCEPT_(__all<__is_nothrow_swappable<const _Tp>::value...>::value)
546    {
547        _VSTD::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t))...);
548    }
549};
550
551template<class _Dest, class _Source, size_t ..._Np>
552_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
553void __memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {
554    _VSTD::__swallow(((_VSTD::get<_Np>(__dest) = _VSTD::get<_Np>(__source)), void(), 0)...);
555}
556
557template<class _Dest, class _Source, class ..._Up, size_t ..._Np>
558_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
559void __memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {
560    _VSTD::__swallow(((
561        _VSTD::get<_Np>(__dest) = _VSTD::forward<_Up>(_VSTD::get<_Np>(__source))
562    ), void(), 0)...);
563}
564
565template <class ..._Tp>
566class _LIBCPP_TEMPLATE_VIS tuple
567{
568    typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;
569
570    _BaseT __base_;
571
572    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
573        typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;
574    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
575        const typename tuple_element<_Jp, tuple<_Up...> >::type& get(const tuple<_Up...>&) _NOEXCEPT;
576    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
577        typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT;
578    template <size_t _Jp, class ..._Up> friend _LIBCPP_CONSTEXPR_SINCE_CXX14
579        const typename tuple_element<_Jp, tuple<_Up...> >::type&& get(const tuple<_Up...>&&) _NOEXCEPT;
580public:
581    // [tuple.cnstr]
582
583    // tuple() constructors (including allocator_arg_t variants)
584    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
585        _And<
586            _IsImpDefault<_Tp>... // explicit check
587        >::value
588    , int> = 0>
589    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
590    tuple()
591        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
592    { }
593
594    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
595              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
596        _And<
597            _IsDefault<_Tp>...,
598            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
599        >::value
600    , int> = 0>
601    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
602    explicit tuple()
603        _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
604    { }
605
606    template <class _Alloc, template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
607        _And<
608            _IsImpDefault<_Tp>... // explicit check
609        >::value
610    , int> = 0>
611    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
612    tuple(allocator_arg_t, _Alloc const& __a)
613      : __base_(allocator_arg_t(), __a,
614                    __tuple_indices<>(), __tuple_types<>(),
615                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
616                    __tuple_types<_Tp...>()) {}
617
618    template <class _Alloc,
619              template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
620              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
621        _And<
622            _IsDefault<_Tp>...,
623            _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
624        >::value
625    , int> = 0>
626    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
627    explicit tuple(allocator_arg_t, _Alloc const& __a)
628      : __base_(allocator_arg_t(), __a,
629                    __tuple_indices<>(), __tuple_types<>(),
630                    typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
631                    __tuple_types<_Tp...>()) {}
632
633    // tuple(const T&...) constructors (including allocator_arg_t variants)
634    template <template<class...> class _And = _And, __enable_if_t<
635        _And<
636            _BoolConstant<sizeof...(_Tp) >= 1>,
637            is_copy_constructible<_Tp>...,
638            is_convertible<const _Tp&, _Tp>... // explicit check
639        >::value
640    , int> = 0>
641    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
642    tuple(const _Tp& ... __t)
643        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
644        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
645                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
646                typename __make_tuple_indices<0>::type(),
647                typename __make_tuple_types<tuple, 0>::type(),
648                __t...
649               ) {}
650
651    template <template<class...> class _And = _And, __enable_if_t<
652        _And<
653            _BoolConstant<sizeof...(_Tp) >= 1>,
654            is_copy_constructible<_Tp>...,
655            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
656        >::value
657    , int> = 0>
658    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
659    explicit tuple(const _Tp& ... __t)
660        _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)
661        : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),
662                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
663                typename __make_tuple_indices<0>::type(),
664                typename __make_tuple_types<tuple, 0>::type(),
665                __t...
666               ) {}
667
668    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
669        _And<
670            _BoolConstant<sizeof...(_Tp) >= 1>,
671            is_copy_constructible<_Tp>...,
672            is_convertible<const _Tp&, _Tp>... // explicit check
673        >::value
674    , int> = 0>
675    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
676    tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
677        : __base_(allocator_arg_t(), __a,
678                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
679                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
680                typename __make_tuple_indices<0>::type(),
681                typename __make_tuple_types<tuple, 0>::type(),
682                __t...
683               ) {}
684
685    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
686        _And<
687            _BoolConstant<sizeof...(_Tp) >= 1>,
688            is_copy_constructible<_Tp>...,
689            _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> > // explicit check
690        >::value
691    , int> = 0>
692    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
693    explicit tuple(allocator_arg_t, const _Alloc& __a, const _Tp& ... __t)
694        : __base_(allocator_arg_t(), __a,
695                typename __make_tuple_indices<sizeof...(_Tp)>::type(),
696                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),
697                typename __make_tuple_indices<0>::type(),
698                typename __make_tuple_types<tuple, 0>::type(),
699                __t...
700               ) {}
701
702    // tuple(U&& ...) constructors (including allocator_arg_t variants)
703    template <class ..._Up> struct _IsThisTuple : false_type { };
704    template <class _Up> struct _IsThisTuple<_Up> : is_same<__remove_cvref_t<_Up>, tuple> { };
705
706    template <class ..._Up>
707    struct _EnableUTypesCtor : _And<
708        _BoolConstant<sizeof...(_Tp) >= 1>,
709        _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
710        is_constructible<_Tp, _Up>...
711    > { };
712
713    template <class ..._Up, __enable_if_t<
714        _And<
715            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
716            _EnableUTypesCtor<_Up...>,
717            is_convertible<_Up, _Tp>... // explicit check
718        >::value
719    , int> = 0>
720    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
721    tuple(_Up&&... __u)
722        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
723        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
724                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
725                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
726                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
727                    _VSTD::forward<_Up>(__u)...) {}
728
729    template <class ..._Up, __enable_if_t<
730        _And<
731            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
732            _EnableUTypesCtor<_Up...>,
733            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
734        >::value
735    , int> = 0>
736    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
737    explicit tuple(_Up&&... __u)
738        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
739        : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),
740                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
741                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
742                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
743                    _VSTD::forward<_Up>(__u)...) {}
744
745    template <class _Alloc, class ..._Up, __enable_if_t<
746        _And<
747            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
748            _EnableUTypesCtor<_Up...>,
749            is_convertible<_Up, _Tp>... // explicit check
750        >::value
751    , int> = 0>
752    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
753    tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
754        : __base_(allocator_arg_t(), __a,
755                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
756                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
757                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
758                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
759                    _VSTD::forward<_Up>(__u)...) {}
760
761    template <class _Alloc, class ..._Up, __enable_if_t<
762        _And<
763            _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
764            _EnableUTypesCtor<_Up...>,
765            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
766        >::value
767    , int> = 0>
768    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
769    explicit tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)
770        : __base_(allocator_arg_t(), __a,
771                    typename __make_tuple_indices<sizeof...(_Up)>::type(),
772                    typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),
773                    typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),
774                    typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
775                    _VSTD::forward<_Up>(__u)...) {}
776
777    // Copy and move constructors (including the allocator_arg_t variants)
778    tuple(const tuple&) = default;
779    tuple(tuple&&) = default;
780
781    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
782        _And<is_copy_constructible<_Tp>...>::value
783    , int> = 0>
784    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
785    tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)
786        : __base_(allocator_arg_t(), __alloc, __t)
787    { }
788
789    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
790        _And<is_move_constructible<_Tp>...>::value
791    , int> = 0>
792    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
793    tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)
794        : __base_(allocator_arg_t(), __alloc, _VSTD::move(__t))
795    { }
796
797    // tuple(const tuple<U...>&) constructors (including allocator_arg_t variants)
798
799    template <class _OtherTuple, class _DecayedOtherTuple = __remove_cvref_t<_OtherTuple>, class = void>
800    struct _EnableCtorFromUTypesTuple : false_type {};
801
802    template <class _OtherTuple, class... _Up>
803    struct _EnableCtorFromUTypesTuple<_OtherTuple, tuple<_Up...>,
804              // the length of the packs needs to checked first otherwise the 2 packs cannot be expanded simultaneously below
805               __enable_if_t<sizeof...(_Up) == sizeof...(_Tp)>> : _And<
806        // the two conditions below are not in spec. The purpose is to disable the UTypes Ctor when copy/move Ctor can work.
807        // Otherwise, is_constructible can trigger hard error in those cases https://godbolt.org/z/M94cGdKcE
808        _Not<is_same<_OtherTuple, const tuple&> >,
809        _Not<is_same<_OtherTuple, tuple&&> >,
810        is_constructible<_Tp, __copy_cvref_t<_OtherTuple, _Up> >...,
811        _Lazy<_Or, _BoolConstant<sizeof...(_Tp) != 1>,
812            // _Tp and _Up are 1-element packs - the pack expansions look
813            // weird to avoid tripping up the type traits in degenerate cases
814            _Lazy<_And,
815                _Not<is_same<_Tp, _Up> >...,
816                _Not<is_convertible<_OtherTuple, _Tp> >...,
817                _Not<is_constructible<_Tp, _OtherTuple> >...
818            >
819        >
820    > {};
821
822    template <class ..._Up, __enable_if_t<
823        _And<
824            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
825            is_convertible<const _Up&, _Tp>... // explicit check
826        >::value
827    , int> = 0>
828    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
829    tuple(const tuple<_Up...>& __t)
830        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
831        : __base_(__t)
832    { }
833
834    template <class ..._Up, __enable_if_t<
835        _And<
836            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
837            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
838        >::value
839    , int> = 0>
840    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
841    explicit tuple(const tuple<_Up...>& __t)
842        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))
843        : __base_(__t)
844    { }
845
846    template <class ..._Up, class _Alloc, __enable_if_t<
847        _And<
848            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
849            is_convertible<const _Up&, _Tp>... // explicit check
850        >::value
851    , int> = 0>
852    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
853    tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
854        : __base_(allocator_arg_t(), __a, __t)
855    { }
856
857    template <class ..._Up, class _Alloc, __enable_if_t<
858        _And<
859            _EnableCtorFromUTypesTuple<const tuple<_Up...>&>,
860            _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> > // explicit check
861        >::value
862    , int> = 0>
863    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
864    explicit tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)
865        : __base_(allocator_arg_t(), __a, __t)
866    { }
867
868#if _LIBCPP_STD_VER > 20
869    // tuple(tuple<U...>&) constructors (including allocator_arg_t variants)
870
871    template <class... _Up, enable_if_t<
872        _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
873    _LIBCPP_HIDE_FROM_ABI constexpr
874        explicit(!(is_convertible_v<_Up&, _Tp> && ...))
875    tuple(tuple<_Up...>& __t) : __base_(__t) {}
876
877    template <class _Alloc, class... _Up, enable_if_t<
878        _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>
879    _LIBCPP_HIDE_FROM_ABI constexpr
880        explicit(!(is_convertible_v<_Up&, _Tp> && ...))
881    tuple(allocator_arg_t, const _Alloc& __alloc, tuple<_Up...>& __t) : __base_(allocator_arg_t(), __alloc, __t) {}
882#endif // _LIBCPP_STD_VER > 20
883
884    // tuple(tuple<U...>&&) constructors (including allocator_arg_t variants)
885
886    template <class ..._Up, __enable_if_t<
887        _And<
888            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
889            is_convertible<_Up, _Tp>... // explicit check
890        >::value
891    , int> = 0>
892    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
893    tuple(tuple<_Up...>&& __t)
894        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
895        : __base_(_VSTD::move(__t))
896    { }
897
898    template <class ..._Up, __enable_if_t<
899        _And<
900            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
901            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
902        >::value
903    , int> = 0>
904    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
905    explicit tuple(tuple<_Up...>&& __t)
906        _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))
907        : __base_(_VSTD::move(__t))
908    { }
909
910    template <class _Alloc, class ..._Up, __enable_if_t<
911        _And<
912            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
913            is_convertible<_Up, _Tp>... // explicit check
914        >::value
915    , int> = 0>
916    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
917    tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
918        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
919    { }
920
921    template <class _Alloc, class ..._Up, __enable_if_t<
922        _And<
923            _EnableCtorFromUTypesTuple<tuple<_Up...>&&>,
924            _Not<_Lazy<_And, is_convertible<_Up, _Tp>...> > // explicit check
925        >::value
926    , int> = 0>
927    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
928    explicit tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)
929        : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
930    { }
931
932#if _LIBCPP_STD_VER > 20
933    // tuple(const tuple<U...>&&) constructors (including allocator_arg_t variants)
934
935    template <class... _Up, enable_if_t<
936        _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
937    _LIBCPP_HIDE_FROM_ABI constexpr
938        explicit(!(is_convertible_v<const _Up&&, _Tp> && ...))
939    tuple(const tuple<_Up...>&& __t) : __base_(std::move(__t)) {}
940
941    template <class _Alloc, class... _Up, enable_if_t<
942        _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>
943    _LIBCPP_HIDE_FROM_ABI constexpr
944        explicit(!(is_convertible_v<const _Up&&, _Tp> && ...))
945    tuple(allocator_arg_t, const _Alloc& __alloc, const tuple<_Up...>&& __t)
946        : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}
947#endif // _LIBCPP_STD_VER > 20
948
949    // tuple(const pair<U1, U2>&) constructors (including allocator_arg_t variants)
950
951    template <template <class...> class Pred, class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
952    struct _CtorPredicateFromPair : false_type{};
953
954    template <template <class...> class Pred, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
955    struct _CtorPredicateFromPair<Pred, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > : _And<
956        Pred<_Tp1, __copy_cvref_t<_Pair, _Up1> >,
957        Pred<_Tp2, __copy_cvref_t<_Pair, _Up2> >
958    > {};
959
960    template <class _Pair>
961    struct _EnableCtorFromPair : _CtorPredicateFromPair<is_constructible, _Pair>{};
962
963    template <class _Pair>
964    struct _NothrowConstructibleFromPair : _CtorPredicateFromPair<is_nothrow_constructible, _Pair>{};
965
966    template <class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
967    struct _BothImplicitlyConvertible : false_type{};
968
969    template <class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
970    struct _BothImplicitlyConvertible<_Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > : _And<
971        is_convertible<__copy_cvref_t<_Pair, _Up1>, _Tp1>,
972        is_convertible<__copy_cvref_t<_Pair, _Up2>, _Tp2>
973    > {};
974
975    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
976        _And<
977            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
978            _BothImplicitlyConvertible<const pair<_Up1, _Up2>&> // explicit check
979        >::value
980    , int> = 0>
981    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
982    tuple(const pair<_Up1, _Up2>& __p)
983        _NOEXCEPT_((_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value))
984        : __base_(__p)
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            _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> > // explicit check
991        >::value
992    , int> = 0>
993    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
994    explicit tuple(const pair<_Up1, _Up2>& __p)
995        _NOEXCEPT_((_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value))
996        : __base_(__p)
997    { }
998
999    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1000        _And<
1001            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
1002            _BothImplicitlyConvertible<const pair<_Up1, _Up2>&> // explicit check
1003        >::value
1004    , int> = 0>
1005    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1006    tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
1007        : __base_(allocator_arg_t(), __a, __p)
1008    { }
1009
1010    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1011        _And<
1012            _EnableCtorFromPair<const pair<_Up1, _Up2>&>,
1013            _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> > // explicit check
1014        >::value
1015    , int> = 0>
1016    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1017    explicit tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)
1018        : __base_(allocator_arg_t(), __a, __p)
1019    { }
1020
1021#if _LIBCPP_STD_VER > 20
1022    // tuple(pair<U1, U2>&) constructors (including allocator_arg_t variants)
1023
1024    template <class _U1, class _U2, enable_if_t<
1025        _EnableCtorFromPair<pair<_U1, _U2>&>::value>* = nullptr>
1026    _LIBCPP_HIDE_FROM_ABI constexpr
1027        explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
1028    tuple(pair<_U1, _U2>& __p) : __base_(__p) {}
1029
1030    template <class _Alloc, class _U1, class _U2, enable_if_t<
1031        _EnableCtorFromPair<std::pair<_U1, _U2>&>::value>* = nullptr>
1032    _LIBCPP_HIDE_FROM_ABI constexpr
1033        explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)
1034    tuple(allocator_arg_t, const _Alloc& __alloc, pair<_U1, _U2>& __p) : __base_(allocator_arg_t(), __alloc, __p) {}
1035#endif
1036
1037    // tuple(pair<U1, U2>&&) constructors (including allocator_arg_t variants)
1038
1039    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1040        _And<
1041            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1042            _BothImplicitlyConvertible<pair<_Up1, _Up2>&&> // explicit check
1043        >::value
1044    , int> = 0>
1045    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1046    tuple(pair<_Up1, _Up2>&& __p)
1047        _NOEXCEPT_((_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value))
1048        : __base_(_VSTD::move(__p))
1049    { }
1050
1051    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1052        _And<
1053            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1054            _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> > // explicit check
1055        >::value
1056    , int> = 0>
1057    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1058    explicit tuple(pair<_Up1, _Up2>&& __p)
1059        _NOEXCEPT_((_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value))
1060        : __base_(_VSTD::move(__p))
1061    { }
1062
1063    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1064        _And<
1065            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1066            _BothImplicitlyConvertible<pair<_Up1, _Up2>&&> // explicit check
1067        >::value
1068    , int> = 0>
1069    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1070    tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
1071        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
1072    { }
1073
1074    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
1075        _And<
1076            _EnableCtorFromPair<pair<_Up1, _Up2>&&>,
1077            _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> > // explicit check
1078        >::value
1079    , int> = 0>
1080    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1081    explicit tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)
1082        : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
1083    { }
1084
1085#if _LIBCPP_STD_VER > 20
1086    // tuple(const pair<U1, U2>&&) constructors (including allocator_arg_t variants)
1087
1088    template <class _U1, class _U2, enable_if_t<
1089        _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
1090    _LIBCPP_HIDE_FROM_ABI constexpr
1091        explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
1092    tuple(const pair<_U1, _U2>&& __p) : __base_(std::move(__p)) {}
1093
1094    template <class _Alloc, class _U1, class _U2, enable_if_t<
1095        _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>
1096    _LIBCPP_HIDE_FROM_ABI constexpr
1097        explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)
1098    tuple(allocator_arg_t, const _Alloc& __alloc, const pair<_U1, _U2>&& __p)
1099        : __base_(allocator_arg_t(), __alloc, std::move(__p)) {}
1100#endif // _LIBCPP_STD_VER > 20
1101
1102    // [tuple.assign]
1103    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1104    tuple& operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple)
1105        _NOEXCEPT_((_And<is_nothrow_copy_assignable<_Tp>...>::value))
1106    {
1107        _VSTD::__memberwise_copy_assign(*this, __tuple,
1108            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1109        return *this;
1110    }
1111
1112#if _LIBCPP_STD_VER > 20
1113    _LIBCPP_HIDE_FROM_ABI constexpr
1114    const tuple& operator=(tuple const& __tuple) const
1115      requires (_And<is_copy_assignable<const _Tp>...>::value) {
1116        std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());
1117        return *this;
1118    }
1119
1120    _LIBCPP_HIDE_FROM_ABI constexpr
1121    const tuple& operator=(tuple&& __tuple) const
1122      requires (_And<is_assignable<const _Tp&, _Tp>...>::value) {
1123        std::__memberwise_forward_assign(*this,
1124                                         std::move(__tuple),
1125                                         __tuple_types<_Tp...>(),
1126                                         typename __make_tuple_indices<sizeof...(_Tp)>::type());
1127        return *this;
1128    }
1129#endif // _LIBCPP_STD_VER > 20
1130
1131    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1132    tuple& operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple)
1133        _NOEXCEPT_((_And<is_nothrow_move_assignable<_Tp>...>::value))
1134    {
1135        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
1136            __tuple_types<_Tp...>(),
1137            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1138        return *this;
1139    }
1140
1141    template<class... _Up, __enable_if_t<
1142        _And<
1143            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
1144            is_assignable<_Tp&, _Up const&>...
1145        >::value
1146    ,int> = 0>
1147    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1148    tuple& operator=(tuple<_Up...> const& __tuple)
1149        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
1150    {
1151        _VSTD::__memberwise_copy_assign(*this, __tuple,
1152            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1153        return *this;
1154    }
1155
1156    template<class... _Up, __enable_if_t<
1157        _And<
1158            _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
1159            is_assignable<_Tp&, _Up>...
1160        >::value
1161    ,int> = 0>
1162    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1163    tuple& operator=(tuple<_Up...>&& __tuple)
1164        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
1165    {
1166        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__tuple),
1167            __tuple_types<_Up...>(),
1168            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1169        return *this;
1170    }
1171
1172
1173#if _LIBCPP_STD_VER > 20
1174    template <class... _UTypes, enable_if_t<
1175        _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
1176             is_assignable<const _Tp&, const _UTypes&>...>::value>* = nullptr>
1177    _LIBCPP_HIDE_FROM_ABI constexpr
1178    const tuple& operator=(const tuple<_UTypes...>& __u) const {
1179        std::__memberwise_copy_assign(*this,
1180                                      __u,
1181                                      typename __make_tuple_indices<sizeof...(_Tp)>::type());
1182        return *this;
1183    }
1184
1185    template <class... _UTypes, enable_if_t<
1186        _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,
1187             is_assignable<const _Tp&, _UTypes>...>::value>* = nullptr>
1188    _LIBCPP_HIDE_FROM_ABI constexpr
1189    const tuple& operator=(tuple<_UTypes...>&& __u) const {
1190        std::__memberwise_forward_assign(*this,
1191                                         __u,
1192                                         __tuple_types<_UTypes...>(),
1193                                         typename __make_tuple_indices<sizeof...(_Tp)>::type());
1194        return *this;
1195    }
1196#endif // _LIBCPP_STD_VER > 20
1197
1198    template <template<class...> class Pred, bool _Const,
1199              class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>
1200    struct _AssignPredicateFromPair : false_type {};
1201
1202    template <template<class...> class Pred, bool _Const,
1203              class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>
1204    struct _AssignPredicateFromPair<Pred, _Const, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> > :
1205        _And<Pred<__maybe_const<_Const, _Tp1>&, __copy_cvref_t<_Pair, _Up1> >,
1206             Pred<__maybe_const<_Const, _Tp2>&, __copy_cvref_t<_Pair, _Up2> >
1207            > {};
1208
1209    template <bool _Const, class _Pair>
1210    struct _EnableAssignFromPair : _AssignPredicateFromPair<is_assignable, _Const, _Pair> {};
1211
1212    template <bool _Const, class _Pair>
1213    struct _NothrowAssignFromPair : _AssignPredicateFromPair<is_nothrow_assignable, _Const, _Pair> {};
1214
1215#if _LIBCPP_STD_VER > 20
1216    template <class _U1, class _U2, enable_if_t<
1217        _EnableAssignFromPair<true, const pair<_U1, _U2>&>::value>* = nullptr>
1218    _LIBCPP_HIDE_FROM_ABI constexpr
1219    const tuple& operator=(const pair<_U1, _U2>& __pair) const
1220      noexcept(_NothrowAssignFromPair<true, const pair<_U1, _U2>&>::value) {
1221        std::get<0>(*this) = __pair.first;
1222        std::get<1>(*this) = __pair.second;
1223        return *this;
1224    }
1225
1226    template <class _U1, class _U2, enable_if_t<
1227        _EnableAssignFromPair<true, pair<_U1, _U2>&&>::value>* = nullptr>
1228    _LIBCPP_HIDE_FROM_ABI constexpr
1229    const tuple& operator=(pair<_U1, _U2>&& __pair) const
1230      noexcept(_NothrowAssignFromPair<true, pair<_U1, _U2>&&>::value) {
1231        std::get<0>(*this) = std::move(__pair.first);
1232        std::get<1>(*this) = std::move(__pair.second);
1233        return *this;
1234    }
1235#endif // _LIBCPP_STD_VER > 20
1236
1237    template<class _Up1, class _Up2, __enable_if_t<
1238        _EnableAssignFromPair<false, pair<_Up1, _Up2> const&>::value
1239    ,int> = 0>
1240    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1241    tuple& operator=(pair<_Up1, _Up2> const& __pair)
1242        _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2> const&>::value))
1243    {
1244        _VSTD::get<0>(*this) = __pair.first;
1245        _VSTD::get<1>(*this) = __pair.second;
1246        return *this;
1247    }
1248
1249    template<class _Up1, class _Up2, __enable_if_t<
1250        _EnableAssignFromPair<false, pair<_Up1, _Up2>&&>::value
1251    ,int> = 0>
1252    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1253    tuple& operator=(pair<_Up1, _Up2>&& __pair)
1254        _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2>&&>::value))
1255    {
1256        _VSTD::get<0>(*this) = _VSTD::forward<_Up1>(__pair.first);
1257        _VSTD::get<1>(*this) = _VSTD::forward<_Up2>(__pair.second);
1258        return *this;
1259    }
1260
1261    // EXTENSION
1262    template<class _Up, size_t _Np, class = __enable_if_t<
1263        _And<
1264            _BoolConstant<_Np == sizeof...(_Tp)>,
1265            is_assignable<_Tp&, _Up const&>...
1266        >::value
1267    > >
1268    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1269    tuple& operator=(array<_Up, _Np> const& __array)
1270        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value))
1271    {
1272        _VSTD::__memberwise_copy_assign(*this, __array,
1273            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1274        return *this;
1275    }
1276
1277    // EXTENSION
1278    template<class _Up, size_t _Np, class = void, class = __enable_if_t<
1279        _And<
1280            _BoolConstant<_Np == sizeof...(_Tp)>,
1281            is_assignable<_Tp&, _Up>...
1282        >::value
1283    > >
1284    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1285    tuple& operator=(array<_Up, _Np>&& __array)
1286        _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value))
1287    {
1288        _VSTD::__memberwise_forward_assign(*this, _VSTD::move(__array),
1289            __tuple_types<_If<true, _Up, _Tp>...>(),
1290            typename __make_tuple_indices<sizeof...(_Tp)>::type());
1291        return *this;
1292    }
1293
1294    // [tuple.swap]
1295    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1296    void swap(tuple& __t) _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
1297        {__base_.swap(__t.__base_);}
1298
1299#if _LIBCPP_STD_VER > 20
1300    _LIBCPP_HIDE_FROM_ABI constexpr
1301    void swap(const tuple& __t) const noexcept(__all<is_nothrow_swappable_v<const _Tp&>...>::value) {
1302        __base_.swap(__t.__base_);
1303    }
1304#endif // _LIBCPP_STD_VER > 20
1305};
1306
1307template <>
1308class _LIBCPP_TEMPLATE_VIS tuple<>
1309{
1310public:
1311    _LIBCPP_INLINE_VISIBILITY constexpr
1312        tuple() _NOEXCEPT = default;
1313    template <class _Alloc>
1314    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1315        tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
1316    template <class _Alloc>
1317    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1318        tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}
1319    template <class _Up>
1320    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1321        tuple(array<_Up, 0>) _NOEXCEPT {}
1322    template <class _Alloc, class _Up>
1323    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1324        tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}
1325    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1326    void swap(tuple&) _NOEXCEPT {}
1327#if _LIBCPP_STD_VER > 20
1328    _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple&) const noexcept {}
1329#endif
1330};
1331
1332#if _LIBCPP_STD_VER > 20
1333template <class... _TTypes, class... _UTypes, template<class> class _TQual, template<class> class _UQual>
1334    requires requires { typename tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>; }
1335struct basic_common_reference<tuple<_TTypes...>, tuple<_UTypes...>, _TQual, _UQual> {
1336    using type = tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>;
1337};
1338
1339template <class... _TTypes, class... _UTypes>
1340    requires requires { typename tuple<common_type_t<_TTypes, _UTypes>...>; }
1341struct common_type<tuple<_TTypes...>, tuple<_UTypes...>> {
1342    using type = tuple<common_type_t<_TTypes, _UTypes>...>;
1343};
1344#endif // _LIBCPP_STD_VER > 20
1345
1346#if _LIBCPP_STD_VER > 14
1347template <class ..._Tp>
1348tuple(_Tp...) -> tuple<_Tp...>;
1349template <class _Tp1, class _Tp2>
1350tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1351template <class _Alloc, class ..._Tp>
1352tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;
1353template <class _Alloc, class _Tp1, class _Tp2>
1354tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
1355template <class _Alloc, class ..._Tp>
1356tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;
1357#endif
1358
1359template <class ..._Tp>
1360inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1361__enable_if_t<__all<__is_swappable<_Tp>::value...>::value, void>
1362swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)
1363                 _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value)
1364    {__t.swap(__u);}
1365
1366#if _LIBCPP_STD_VER > 20
1367template <class... _Tp>
1368_LIBCPP_HIDE_FROM_ABI constexpr
1369enable_if_t<__all<is_swappable_v<const _Tp>...>::value, void>
1370swap(const tuple<_Tp...>& __lhs, const tuple<_Tp...>& __rhs)
1371        noexcept(__all<is_nothrow_swappable_v<const _Tp>...>::value) {
1372    __lhs.swap(__rhs);
1373}
1374#endif
1375
1376// get
1377
1378template <size_t _Ip, class ..._Tp>
1379inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1380typename tuple_element<_Ip, tuple<_Tp...> >::type&
1381get(tuple<_Tp...>& __t) _NOEXCEPT
1382{
1383    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1384    return static_cast<__tuple_leaf<_Ip, type>&>(__t.__base_).get();
1385}
1386
1387template <size_t _Ip, class ..._Tp>
1388inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1389const typename tuple_element<_Ip, tuple<_Tp...> >::type&
1390get(const tuple<_Tp...>& __t) _NOEXCEPT
1391{
1392    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1393    return static_cast<const __tuple_leaf<_Ip, type>&>(__t.__base_).get();
1394}
1395
1396template <size_t _Ip, class ..._Tp>
1397inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1398typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1399get(tuple<_Tp...>&& __t) _NOEXCEPT
1400{
1401    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1402    return static_cast<type&&>(
1403             static_cast<__tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1404}
1405
1406template <size_t _Ip, class ..._Tp>
1407inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1408const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
1409get(const tuple<_Tp...>&& __t) _NOEXCEPT
1410{
1411    typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;
1412    return static_cast<const type&&>(
1413             static_cast<const __tuple_leaf<_Ip, type>&&>(__t.__base_).get());
1414}
1415
1416#if _LIBCPP_STD_VER > 11
1417
1418namespace __find_detail {
1419
1420static constexpr size_t __not_found = static_cast<size_t>(-1);
1421static constexpr size_t __ambiguous = __not_found - 1;
1422
1423inline _LIBCPP_INLINE_VISIBILITY
1424constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) {
1425    return !__matches ? __res :
1426        (__res == __not_found ? __curr_i : __ambiguous);
1427}
1428
1429template <size_t _Nx>
1430inline _LIBCPP_INLINE_VISIBILITY
1431constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {
1432  return __i == _Nx ? __not_found :
1433      __find_detail::__find_idx_return(__i, __find_detail::__find_idx(__i + 1, __matches), __matches[__i]);
1434}
1435
1436template <class _T1, class ..._Args>
1437struct __find_exactly_one_checked {
1438    static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...};
1439    static constexpr size_t value = __find_detail::__find_idx(0, __matches);
1440    static_assert(value != __not_found, "type not found in type list" );
1441    static_assert(value != __ambiguous, "type occurs more than once in type list");
1442};
1443
1444template <class _T1>
1445struct __find_exactly_one_checked<_T1> {
1446    static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");
1447};
1448
1449} // namespace __find_detail
1450
1451template <typename _T1, typename... _Args>
1452struct __find_exactly_one_t
1453    : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {
1454};
1455
1456template <class _T1, class... _Args>
1457inline _LIBCPP_INLINE_VISIBILITY
1458constexpr _T1& get(tuple<_Args...>& __tup) noexcept
1459{
1460    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1461}
1462
1463template <class _T1, class... _Args>
1464inline _LIBCPP_INLINE_VISIBILITY
1465constexpr _T1 const& get(tuple<_Args...> const& __tup) noexcept
1466{
1467    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);
1468}
1469
1470template <class _T1, class... _Args>
1471inline _LIBCPP_INLINE_VISIBILITY
1472constexpr _T1&& get(tuple<_Args...>&& __tup) noexcept
1473{
1474    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
1475}
1476
1477template <class _T1, class... _Args>
1478inline _LIBCPP_INLINE_VISIBILITY
1479constexpr _T1 const&& get(tuple<_Args...> const&& __tup) noexcept
1480{
1481    return _VSTD::get<__find_exactly_one_t<_T1, _Args...>::value>(_VSTD::move(__tup));
1482}
1483
1484#endif
1485
1486// tie
1487
1488template <class ..._Tp>
1489inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1490tuple<_Tp&...>
1491tie(_Tp&... __t) _NOEXCEPT
1492{
1493    return tuple<_Tp&...>(__t...);
1494}
1495
1496template <class _Up>
1497struct __ignore_t
1498{
1499    template <class _Tp>
1500    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1501    const __ignore_t& operator=(_Tp&&) const {return *this;}
1502};
1503
1504namespace {
1505  constexpr __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>();
1506} // namespace
1507
1508template <class... _Tp>
1509inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1510tuple<typename __unwrap_ref_decay<_Tp>::type...>
1511make_tuple(_Tp&&... __t)
1512{
1513    return tuple<typename __unwrap_ref_decay<_Tp>::type...>(_VSTD::forward<_Tp>(__t)...);
1514}
1515
1516template <class... _Tp>
1517inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1518tuple<_Tp&&...>
1519forward_as_tuple(_Tp&&... __t) _NOEXCEPT
1520{
1521    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
1522}
1523
1524template <size_t _Ip>
1525struct __tuple_equal
1526{
1527    template <class _Tp, class _Up>
1528    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1529    bool operator()(const _Tp& __x, const _Up& __y)
1530    {
1531        return __tuple_equal<_Ip - 1>()(__x, __y) && _VSTD::get<_Ip-1>(__x) == _VSTD::get<_Ip-1>(__y);
1532    }
1533};
1534
1535template <>
1536struct __tuple_equal<0>
1537{
1538    template <class _Tp, class _Up>
1539    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1540    bool operator()(const _Tp&, const _Up&)
1541    {
1542        return true;
1543    }
1544};
1545
1546template <class ..._Tp, class ..._Up>
1547inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1548bool
1549operator==(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1550{
1551    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1552    return __tuple_equal<sizeof...(_Tp)>()(__x, __y);
1553}
1554
1555#if _LIBCPP_STD_VER > 17
1556
1557// operator<=>
1558
1559template <class ..._Tp, class ..._Up, size_t ..._Is>
1560_LIBCPP_HIDE_FROM_ABI constexpr
1561auto
1562__tuple_compare_three_way(const tuple<_Tp...>& __x, const tuple<_Up...>& __y, index_sequence<_Is...>) {
1563    common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...> __result = strong_ordering::equal;
1564    static_cast<void>(((__result = _VSTD::__synth_three_way(_VSTD::get<_Is>(__x), _VSTD::get<_Is>(__y)), __result != 0) || ...));
1565    return __result;
1566}
1567
1568template <class ..._Tp, class ..._Up>
1569requires (sizeof...(_Tp) == sizeof...(_Up))
1570_LIBCPP_HIDE_FROM_ABI constexpr
1571common_comparison_category_t<__synth_three_way_result<_Tp, _Up>...>
1572operator<=>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1573{
1574    return _VSTD::__tuple_compare_three_way(__x, __y, index_sequence_for<_Tp...>{});
1575}
1576
1577#else // _LIBCPP_STD_VER > 17
1578
1579template <class ..._Tp, class ..._Up>
1580inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1581bool
1582operator!=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1583{
1584    return !(__x == __y);
1585}
1586
1587template <size_t _Ip>
1588struct __tuple_less
1589{
1590    template <class _Tp, class _Up>
1591    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1592    bool operator()(const _Tp& __x, const _Up& __y)
1593    {
1594        const size_t __idx = tuple_size<_Tp>::value - _Ip;
1595        if (_VSTD::get<__idx>(__x) < _VSTD::get<__idx>(__y))
1596            return true;
1597        if (_VSTD::get<__idx>(__y) < _VSTD::get<__idx>(__x))
1598            return false;
1599        return __tuple_less<_Ip-1>()(__x, __y);
1600    }
1601};
1602
1603template <>
1604struct __tuple_less<0>
1605{
1606    template <class _Tp, class _Up>
1607    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1608    bool operator()(const _Tp&, const _Up&)
1609    {
1610        return false;
1611    }
1612};
1613
1614template <class ..._Tp, class ..._Up>
1615inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1616bool
1617operator<(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1618{
1619    static_assert (sizeof...(_Tp) == sizeof...(_Up), "Can't compare tuples of different sizes");
1620    return __tuple_less<sizeof...(_Tp)>()(__x, __y);
1621}
1622
1623template <class ..._Tp, class ..._Up>
1624inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1625bool
1626operator>(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1627{
1628    return __y < __x;
1629}
1630
1631template <class ..._Tp, class ..._Up>
1632inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1633bool
1634operator>=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1635{
1636    return !(__x < __y);
1637}
1638
1639template <class ..._Tp, class ..._Up>
1640inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1641bool
1642operator<=(const tuple<_Tp...>& __x, const tuple<_Up...>& __y)
1643{
1644    return !(__y < __x);
1645}
1646
1647#endif // _LIBCPP_STD_VER > 17
1648
1649// tuple_cat
1650
1651template <class _Tp, class _Up> struct __tuple_cat_type;
1652
1653template <class ..._Ttypes, class ..._Utypes>
1654struct __tuple_cat_type<tuple<_Ttypes...>, __tuple_types<_Utypes...> >
1655{
1656    typedef _LIBCPP_NODEBUG tuple<_Ttypes..., _Utypes...> type;
1657};
1658
1659template <class _ResultTuple, bool _Is_Tuple0TupleLike, class ..._Tuples>
1660struct __tuple_cat_return_1
1661{
1662};
1663
1664template <class ..._Types, class _Tuple0>
1665struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0>
1666{
1667  using type _LIBCPP_NODEBUG = typename __tuple_cat_type<
1668      tuple<_Types...>,
1669      typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type
1670    >::type;
1671};
1672
1673template <class ..._Types, class _Tuple0, class _Tuple1, class ..._Tuples>
1674struct __tuple_cat_return_1<tuple<_Types...>, true, _Tuple0, _Tuple1, _Tuples...>
1675    : public __tuple_cat_return_1<
1676                 typename __tuple_cat_type<
1677                     tuple<_Types...>,
1678                     typename __make_tuple_types<__remove_cvref_t<_Tuple0> >::type
1679                 >::type,
1680                 __tuple_like_ext<__libcpp_remove_reference_t<_Tuple1> >::value,
1681                 _Tuple1, _Tuples...>
1682{
1683};
1684
1685template <class ..._Tuples> struct __tuple_cat_return;
1686
1687template <class _Tuple0, class ..._Tuples>
1688struct __tuple_cat_return<_Tuple0, _Tuples...>
1689    : public __tuple_cat_return_1<tuple<>,
1690         __tuple_like_ext<__libcpp_remove_reference_t<_Tuple0> >::value, _Tuple0,
1691                                                                     _Tuples...>
1692{
1693};
1694
1695template <>
1696struct __tuple_cat_return<>
1697{
1698    typedef _LIBCPP_NODEBUG tuple<> type;
1699};
1700
1701inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1702tuple<>
1703tuple_cat()
1704{
1705    return tuple<>();
1706}
1707
1708template <class _Rp, class _Indices, class _Tuple0, class ..._Tuples>
1709struct __tuple_cat_return_ref_imp;
1710
1711template <class ..._Types, size_t ..._I0, class _Tuple0>
1712struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>, _Tuple0>
1713{
1714    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1715    typedef tuple<_Types..., typename __apply_cv<_Tuple0,
1716                          typename tuple_element<_I0, _T0>::type>::type&&...> type;
1717};
1718
1719template <class ..._Types, size_t ..._I0, class _Tuple0, class _Tuple1, class ..._Tuples>
1720struct __tuple_cat_return_ref_imp<tuple<_Types...>, __tuple_indices<_I0...>,
1721                                  _Tuple0, _Tuple1, _Tuples...>
1722    : public __tuple_cat_return_ref_imp<
1723         tuple<_Types..., typename __apply_cv<_Tuple0,
1724               typename tuple_element<_I0,
1725                  __libcpp_remove_reference_t<_Tuple0> >::type>::type&&...>,
1726         typename __make_tuple_indices<tuple_size<__libcpp_remove_reference_t<_Tuple1> >::value>::type,
1727         _Tuple1, _Tuples...>
1728{
1729};
1730
1731template <class _Tuple0, class ..._Tuples>
1732struct __tuple_cat_return_ref
1733    : public __tuple_cat_return_ref_imp<tuple<>,
1734               typename __make_tuple_indices<
1735                        tuple_size<__libcpp_remove_reference_t<_Tuple0> >::value
1736               >::type, _Tuple0, _Tuples...>
1737{
1738};
1739
1740template <class _Types, class _I0, class _J0>
1741struct __tuple_cat;
1742
1743template <class ..._Types, size_t ..._I0, size_t ..._J0>
1744struct __tuple_cat<tuple<_Types...>, __tuple_indices<_I0...>, __tuple_indices<_J0...> >
1745{
1746    template <class _Tuple0>
1747    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1748    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
1749    operator()(tuple<_Types...> __t, _Tuple0&& __t0)
1750    {
1751        (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1752        return _VSTD::forward_as_tuple(
1753            _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1754            _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
1755    }
1756
1757    template <class _Tuple0, class _Tuple1, class ..._Tuples>
1758    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1759    typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&, _Tuple1&&, _Tuples&&...>::type
1760    operator()(tuple<_Types...> __t, _Tuple0&& __t0, _Tuple1&& __t1, _Tuples&& ...__tpls)
1761    {
1762        (void)__t; // avoid unused parameter warning on GCC when _I0 is empty
1763        typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1764        typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple1> _T1;
1765        return __tuple_cat<
1766            tuple<_Types...,
1767                  typename __apply_cv<_Tuple0, typename tuple_element<
1768                                                   _J0, _T0>::type>::type&&...>,
1769            typename __make_tuple_indices<sizeof...(_Types) +
1770                                          tuple_size<_T0>::value>::type,
1771            typename __make_tuple_indices<tuple_size<_T1>::value>::type>()(
1772            _VSTD::forward_as_tuple(
1773                _VSTD::forward<_Types>(_VSTD::get<_I0>(__t))...,
1774                _VSTD::get<_J0>(_VSTD::forward<_Tuple0>(__t0))...),
1775            _VSTD::forward<_Tuple1>(__t1), _VSTD::forward<_Tuples>(__tpls)...);
1776    }
1777};
1778
1779template <class _Tuple0, class... _Tuples>
1780inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
1781typename __tuple_cat_return<_Tuple0, _Tuples...>::type
1782tuple_cat(_Tuple0&& __t0, _Tuples&&... __tpls)
1783{
1784    typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tuple0> _T0;
1785    return __tuple_cat<tuple<>, __tuple_indices<>,
1786                  typename __make_tuple_indices<tuple_size<_T0>::value>::type>()
1787                  (tuple<>(), _VSTD::forward<_Tuple0>(__t0),
1788                                            _VSTD::forward<_Tuples>(__tpls)...);
1789}
1790
1791template <class ..._Tp, class _Alloc>
1792struct _LIBCPP_TEMPLATE_VIS uses_allocator<tuple<_Tp...>, _Alloc>
1793    : true_type {};
1794
1795template <class _T1, class _T2>
1796template <class... _Args1, class... _Args2, size_t ..._I1, size_t ..._I2>
1797inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
1798pair<_T1, _T2>::pair(piecewise_construct_t,
1799                     tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
1800                     __tuple_indices<_I1...>, __tuple_indices<_I2...>)
1801    :  first(_VSTD::forward<_Args1>(_VSTD::get<_I1>( __first_args))...),
1802      second(_VSTD::forward<_Args2>(_VSTD::get<_I2>(__second_args))...)
1803{
1804}
1805
1806#if _LIBCPP_STD_VER > 14
1807template <class _Tp>
1808inline constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
1809
1810#define _LIBCPP_NOEXCEPT_RETURN(...) noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
1811
1812template <class _Fn, class _Tuple, size_t ..._Id>
1813inline _LIBCPP_INLINE_VISIBILITY
1814constexpr decltype(auto) __apply_tuple_impl(_Fn && __f, _Tuple && __t,
1815                                            __tuple_indices<_Id...>)
1816_LIBCPP_NOEXCEPT_RETURN(
1817    _VSTD::__invoke(
1818        _VSTD::forward<_Fn>(__f),
1819        _VSTD::get<_Id>(_VSTD::forward<_Tuple>(__t))...)
1820)
1821
1822template <class _Fn, class _Tuple>
1823inline _LIBCPP_INLINE_VISIBILITY
1824constexpr decltype(auto) apply(_Fn && __f, _Tuple && __t)
1825_LIBCPP_NOEXCEPT_RETURN(
1826    _VSTD::__apply_tuple_impl(
1827        _VSTD::forward<_Fn>(__f), _VSTD::forward<_Tuple>(__t),
1828        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
1829)
1830
1831template <class _Tp, class _Tuple, size_t... _Idx>
1832inline _LIBCPP_INLINE_VISIBILITY
1833constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>)
1834_LIBCPP_NOEXCEPT_RETURN(
1835    _Tp(_VSTD::get<_Idx>(_VSTD::forward<_Tuple>(__t))...)
1836)
1837
1838template <class _Tp, class _Tuple>
1839inline _LIBCPP_INLINE_VISIBILITY
1840constexpr _Tp make_from_tuple(_Tuple&& __t)
1841_LIBCPP_NOEXCEPT_RETURN(
1842    _VSTD::__make_from_tuple_impl<_Tp>(_VSTD::forward<_Tuple>(__t),
1843        typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type{})
1844)
1845
1846#undef _LIBCPP_NOEXCEPT_RETURN
1847
1848#endif // _LIBCPP_STD_VER > 14
1849
1850#endif // !defined(_LIBCPP_CXX03_LANG)
1851
1852_LIBCPP_END_NAMESPACE_STD
1853
1854#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1855#  include <exception>
1856#  include <iosfwd>
1857#  include <new>
1858#  include <type_traits>
1859#  include <typeinfo>
1860#  include <utility>
1861#endif
1862
1863#endif // _LIBCPP_TUPLE
1864