1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP___TUPLE
12#define _LIBCPP___TUPLE
13
14#include <__config>
15#include <cstddef>
16#include <type_traits>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19#pragma GCC system_header
20#endif
21
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY tuple_size;
26
27template <class _Tp>
28class _LIBCPP_TYPE_VIS_ONLY tuple_size<const _Tp>
29    : public tuple_size<_Tp> {};
30
31template <class _Tp>
32class _LIBCPP_TYPE_VIS_ONLY tuple_size<volatile _Tp>
33    : public tuple_size<_Tp> {};
34
35template <class _Tp>
36class _LIBCPP_TYPE_VIS_ONLY tuple_size<const volatile _Tp>
37    : public tuple_size<_Tp> {};
38
39template <size_t _Ip, class _Tp> class _LIBCPP_TYPE_VIS_ONLY tuple_element;
40
41template <size_t _Ip, class _Tp>
42class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, const _Tp>
43{
44public:
45    typedef typename add_const<typename tuple_element<_Ip, _Tp>::type>::type type;
46};
47
48template <size_t _Ip, class _Tp>
49class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, volatile _Tp>
50{
51public:
52    typedef typename add_volatile<typename tuple_element<_Ip, _Tp>::type>::type type;
53};
54
55template <size_t _Ip, class _Tp>
56class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, const volatile _Tp>
57{
58public:
59    typedef typename add_cv<typename tuple_element<_Ip, _Tp>::type>::type type;
60};
61
62template <class _Tp> struct __tuple_like : false_type {};
63
64template <class _Tp> struct __tuple_like<const _Tp> : public __tuple_like<_Tp> {};
65template <class _Tp> struct __tuple_like<volatile _Tp> : public __tuple_like<_Tp> {};
66template <class _Tp> struct __tuple_like<const volatile _Tp> : public __tuple_like<_Tp> {};
67
68// tuple specializations
69
70#if !defined(_LIBCPP_HAS_NO_VARIADICS)
71
72template <size_t...> struct __tuple_indices {};
73
74template <class _IdxType, _IdxType... _Values>
75struct __integer_sequence {
76  template <template <class _OIdxType, _OIdxType...> class _ToIndexSeq, class _ToIndexType>
77  using __convert = _ToIndexSeq<_ToIndexType, _Values...>;
78
79  template <size_t _Sp>
80  using __to_tuple_indices = __tuple_indices<(_Values + _Sp)...>;
81};
82
83#if !__has_builtin(__make_integer_seq) || defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
84namespace __detail {
85
86template<typename _Tp, size_t ..._Extra> struct __repeat;
87template<typename _Tp, _Tp ..._Np, size_t ..._Extra> struct __repeat<__integer_sequence<_Tp, _Np...>, _Extra...> {
88  typedef __integer_sequence<_Tp,
89                           _Np...,
90                           sizeof...(_Np) + _Np...,
91                           2 * sizeof...(_Np) + _Np...,
92                           3 * sizeof...(_Np) + _Np...,
93                           4 * sizeof...(_Np) + _Np...,
94                           5 * sizeof...(_Np) + _Np...,
95                           6 * sizeof...(_Np) + _Np...,
96                           7 * sizeof...(_Np) + _Np...,
97                           _Extra...> type;
98};
99
100template<size_t _Np> struct __parity;
101template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};
102
103template<> struct __make<0> { typedef __integer_sequence<size_t> type; };
104template<> struct __make<1> { typedef __integer_sequence<size_t, 0> type; };
105template<> struct __make<2> { typedef __integer_sequence<size_t, 0, 1> type; };
106template<> struct __make<3> { typedef __integer_sequence<size_t, 0, 1, 2> type; };
107template<> struct __make<4> { typedef __integer_sequence<size_t, 0, 1, 2, 3> type; };
108template<> struct __make<5> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4> type; };
109template<> struct __make<6> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; };
110template<> struct __make<7> { typedef __integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; };
111
112template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
113template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
114template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
115template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
116template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
117template<> struct __parity<5> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
118template<> struct __parity<6> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
119template<> struct __parity<7> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 7, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
120
121} // namespace detail
122
123#endif  // !__has_builtin(__make_integer_seq) || defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
124
125#if __has_builtin(__make_integer_seq)
126template <size_t _Ep, size_t _Sp>
127using __make_indices_imp =
128    typename __make_integer_seq<__integer_sequence, size_t, _Ep - _Sp>::template
129    __to_tuple_indices<_Sp>;
130#else
131template <size_t _Ep, size_t _Sp>
132using __make_indices_imp =
133    typename __detail::__make<_Ep - _Sp>::type::template __to_tuple_indices<_Sp>;
134
135#endif
136
137template <size_t _Ep, size_t _Sp = 0>
138struct __make_tuple_indices
139{
140    static_assert(_Sp <= _Ep, "__make_tuple_indices input error");
141    typedef __make_indices_imp<_Ep, _Sp> type;
142};
143
144
145template <class ..._Tp> class _LIBCPP_TYPE_VIS_ONLY tuple;
146
147template <class... _Tp> struct __tuple_like<tuple<_Tp...> > : true_type {};
148
149template <class ..._Tp>
150class _LIBCPP_TYPE_VIS_ONLY tuple_size<tuple<_Tp...> >
151    : public integral_constant<size_t, sizeof...(_Tp)>
152{
153};
154
155template <size_t _Ip, class ..._Tp>
156_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
157typename tuple_element<_Ip, tuple<_Tp...> >::type&
158get(tuple<_Tp...>&) _NOEXCEPT;
159
160template <size_t _Ip, class ..._Tp>
161_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
162const typename tuple_element<_Ip, tuple<_Tp...> >::type&
163get(const tuple<_Tp...>&) _NOEXCEPT;
164
165template <size_t _Ip, class ..._Tp>
166_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
167typename tuple_element<_Ip, tuple<_Tp...> >::type&&
168get(tuple<_Tp...>&&) _NOEXCEPT;
169
170template <size_t _Ip, class ..._Tp>
171_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
172const typename tuple_element<_Ip, tuple<_Tp...> >::type&&
173get(const tuple<_Tp...>&&) _NOEXCEPT;
174#endif
175
176// pair specializations
177
178template <class _T1, class _T2> struct __tuple_like<pair<_T1, _T2> > : true_type {};
179
180template <size_t _Ip, class _T1, class _T2>
181_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
182typename tuple_element<_Ip, pair<_T1, _T2> >::type&
183get(pair<_T1, _T2>&) _NOEXCEPT;
184
185template <size_t _Ip, class _T1, class _T2>
186_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
187const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
188get(const pair<_T1, _T2>&) _NOEXCEPT;
189
190#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
191template <size_t _Ip, class _T1, class _T2>
192_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
193typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
194get(pair<_T1, _T2>&&) _NOEXCEPT;
195
196template <size_t _Ip, class _T1, class _T2>
197_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
198const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
199get(const pair<_T1, _T2>&&) _NOEXCEPT;
200#endif
201
202// array specializations
203
204template <class _Tp, size_t _Size> struct _LIBCPP_TYPE_VIS_ONLY array;
205
206template <class _Tp, size_t _Size> struct __tuple_like<array<_Tp, _Size> > : true_type {};
207
208template <size_t _Ip, class _Tp, size_t _Size>
209_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
210_Tp&
211get(array<_Tp, _Size>&) _NOEXCEPT;
212
213template <size_t _Ip, class _Tp, size_t _Size>
214_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
215const _Tp&
216get(const array<_Tp, _Size>&) _NOEXCEPT;
217
218#if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES)
219template <size_t _Ip, class _Tp, size_t _Size>
220_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
221_Tp&&
222get(array<_Tp, _Size>&&) _NOEXCEPT;
223
224template <size_t _Ip, class _Tp, size_t _Size>
225_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
226const _Tp&&
227get(const array<_Tp, _Size>&&) _NOEXCEPT;
228#endif
229
230#if !defined(_LIBCPP_HAS_NO_VARIADICS)
231
232
233// __tuple_types
234
235template <class ..._Tp> struct __tuple_types {};
236
237#if !__has_builtin(__type_pack_element)
238
239namespace __indexer_detail {
240
241template <size_t _Idx, class _Tp>
242struct __indexed { using type = _Tp; };
243
244template <class _Types, class _Indexes> struct __indexer;
245
246template <class ..._Types, size_t ..._Idx>
247struct __indexer<__tuple_types<_Types...>, __tuple_indices<_Idx...>>
248    : __indexed<_Idx, _Types>...
249{};
250
251template <size_t _Idx, class _Tp>
252__indexed<_Idx, _Tp> __at_index(__indexed<_Idx, _Tp> const&);
253
254} // namespace __indexer_detail
255
256template <size_t _Idx, class ..._Types>
257using __type_pack_element = typename decltype(
258    __indexer_detail::__at_index<_Idx>(
259        __indexer_detail::__indexer<
260            __tuple_types<_Types...>,
261            typename __make_tuple_indices<sizeof...(_Types)>::type
262        >{})
263  )::type;
264#endif
265
266template <size_t _Ip, class ..._Types>
267class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, __tuple_types<_Types...>>
268{
269public:
270    static_assert(_Ip < sizeof...(_Types), "tuple_element index out of range");
271    typedef __type_pack_element<_Ip, _Types...> type;
272};
273
274
275template <class ..._Tp>
276class _LIBCPP_TYPE_VIS_ONLY tuple_size<__tuple_types<_Tp...> >
277    : public integral_constant<size_t, sizeof...(_Tp)>
278{
279};
280
281template <class... _Tp> struct __tuple_like<__tuple_types<_Tp...> > : true_type {};
282
283template <bool _ApplyLV, bool _ApplyConst, bool _ApplyVolatile>
284struct __apply_cv_mf;
285template <>
286struct __apply_cv_mf<false, false, false> {
287  template <class _Tp> using __apply = _Tp;
288};
289template <>
290struct __apply_cv_mf<false, true, false> {
291  template <class _Tp> using __apply = const _Tp;
292};
293template <>
294struct __apply_cv_mf<false, false, true> {
295  template <class _Tp> using __apply = volatile _Tp;
296};
297template <>
298struct __apply_cv_mf<false, true, true> {
299  template <class _Tp> using __apply = const volatile _Tp;
300};
301template <>
302struct __apply_cv_mf<true, false, false> {
303  template <class _Tp> using __apply = _Tp&;
304};
305template <>
306struct __apply_cv_mf<true, true, false> {
307  template <class _Tp> using __apply = const _Tp&;
308};
309template <>
310struct __apply_cv_mf<true, false, true> {
311  template <class _Tp> using __apply = volatile _Tp&;
312};
313template <>
314struct __apply_cv_mf<true, true, true> {
315  template <class _Tp> using __apply = const volatile _Tp&;
316};
317template <class _Tp, class _RawTp = typename remove_reference<_Tp>::type>
318using __apply_cv_t = __apply_cv_mf<
319    is_lvalue_reference<_Tp>::value,
320    is_const<_RawTp>::value,
321    is_volatile<_RawTp>::value>;
322
323// __make_tuple_types
324
325// __make_tuple_types<_Tuple<_Types...>, _Ep, _Sp>::type is a
326// __tuple_types<_Types...> using only those _Types in the range [_Sp, _Ep).
327// _Sp defaults to 0 and _Ep defaults to tuple_size<_Tuple>.  If _Tuple is a
328// lvalue_reference type, then __tuple_types<_Types&...> is the result.
329
330template <class _TupleTypes, class _TupleIndices>
331struct __make_tuple_types_flat;
332
333template <template <class...> class _Tuple, class ..._Types, size_t ..._Idx>
334struct __make_tuple_types_flat<_Tuple<_Types...>, __tuple_indices<_Idx...>> {
335  // Specialization for pair, tuple, and __tuple_types
336  template <class _Tp, class _ApplyFn = __apply_cv_t<_Tp>>
337  using __apply_quals = __tuple_types<
338      typename _ApplyFn::template __apply<__type_pack_element<_Idx, _Types...>>...
339    >;
340};
341
342template <class _Vt, size_t _Np, size_t ..._Idx>
343struct __make_tuple_types_flat<array<_Vt, _Np>, __tuple_indices<_Idx...>> {
344  template <size_t>
345  using __value_type = _Vt;
346  template <class _Tp, class _ApplyFn = __apply_cv_t<_Tp>>
347  using __apply_quals = __tuple_types<
348      typename _ApplyFn::template __apply<__value_type<_Idx>>...
349    >;
350};
351
352template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value,
353          size_t _Sp = 0,
354          bool _SameSize = (_Ep == tuple_size<typename remove_reference<_Tp>::type>::value)>
355struct __make_tuple_types
356{
357    static_assert(_Sp <= _Ep, "__make_tuple_types input error");
358    using _RawTp = typename remove_cv<typename remove_reference<_Tp>::type>::type;
359    using _Maker = __make_tuple_types_flat<_RawTp, typename __make_tuple_indices<_Ep, _Sp>::type>;
360    using type = typename _Maker::template __apply_quals<_Tp>;
361};
362
363template <class ..._Types, size_t _Ep>
364struct __make_tuple_types<tuple<_Types...>, _Ep, 0, true> {
365  typedef __tuple_types<_Types...> type;
366};
367
368template <class ..._Types, size_t _Ep>
369struct __make_tuple_types<__tuple_types<_Types...>, _Ep, 0, true> {
370  typedef __tuple_types<_Types...> type;
371};
372
373template <bool ..._Preds>
374struct __all_dummy;
375
376template <bool ..._Pred>
377using __all = is_same<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)...>>;
378
379struct __tuple_sfinae_base {
380  template <template <class, class...> class _Trait,
381            class ..._LArgs, class ..._RArgs>
382  static auto __do_test(__tuple_types<_LArgs...>, __tuple_types<_RArgs...>)
383    -> __all<typename enable_if<_Trait<_LArgs, _RArgs>::value, bool>::type{true}...>;
384  template <template <class...> class>
385  static auto __do_test(...) -> false_type;
386
387  template <class _FromArgs, class _ToArgs>
388  using __constructible = decltype(__do_test<is_constructible>(_ToArgs{}, _FromArgs{}));
389  template <class _FromArgs, class _ToArgs>
390  using __convertible = decltype(__do_test<is_convertible>(_FromArgs{}, _ToArgs{}));
391  template <class _FromArgs, class _ToArgs>
392  using __assignable = decltype(__do_test<is_assignable>(_ToArgs{}, _FromArgs{}));
393};
394
395// __tuple_convertible
396
397template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
398                                bool = __tuple_like<_Up>::value>
399struct __tuple_convertible
400    : public false_type {};
401
402template <class _Tp, class _Up>
403struct __tuple_convertible<_Tp, _Up, true, true>
404    : public __tuple_sfinae_base::__convertible<
405      typename __make_tuple_types<_Tp>::type
406    , typename __make_tuple_types<_Up>::type
407    >
408{};
409
410// __tuple_constructible
411
412template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
413                                bool = __tuple_like<_Up>::value>
414struct __tuple_constructible
415    : public false_type {};
416
417template <class _Tp, class _Up>
418struct __tuple_constructible<_Tp, _Up, true, true>
419    : public __tuple_sfinae_base::__constructible<
420      typename __make_tuple_types<_Tp>::type
421    , typename __make_tuple_types<_Up>::type
422    >
423{};
424
425// __tuple_assignable
426
427template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
428                                bool = __tuple_like<_Up>::value>
429struct __tuple_assignable
430    : public false_type {};
431
432template <class _Tp, class _Up>
433struct __tuple_assignable<_Tp, _Up, true, true>
434    : public __tuple_sfinae_base::__assignable<
435      typename __make_tuple_types<_Tp>::type
436    , typename __make_tuple_types<_Up&>::type
437    >
438{};
439
440
441template <size_t _Ip, class ..._Tp>
442class _LIBCPP_TYPE_VIS_ONLY tuple_element<_Ip, tuple<_Tp...> >
443{
444public:
445    typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
446};
447
448#if _LIBCPP_STD_VER > 11
449template <size_t _Ip, class ..._Tp>
450using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type;
451#endif
452
453#endif  // _LIBCPP_HAS_NO_VARIADICS
454
455#ifndef _LIBCPP_CXX03_LANG
456template <bool _IsTuple, class _SizeTrait, size_t _Expected>
457struct __tuple_like_with_size_imp : false_type {};
458
459template <class _SizeTrait, size_t _Expected>
460struct __tuple_like_with_size_imp<true, _SizeTrait, _Expected>
461    : integral_constant<bool, _SizeTrait::value == _Expected> {};
462
463template <class _Tuple, size_t _ExpectedSize,
464          class _RawTuple = typename __uncvref<_Tuple>::type>
465using __tuple_like_with_size = __tuple_like_with_size_imp<
466                                   __tuple_like<_RawTuple>::value,
467                                   tuple_size<_RawTuple>, _ExpectedSize
468                              >;
469
470struct _LIBCPP_TYPE_VIS __check_tuple_constructor_fail {
471    template <class ...>
472    static constexpr bool __enable_default() { return false; }
473    template <class ...>
474    static constexpr bool __enable_explicit() { return false; }
475    template <class ...>
476    static constexpr bool __enable_implicit() { return false; }
477    template <class ...>
478    static constexpr bool __enable_assign() { return false; }
479};
480#endif
481
482#if _LIBCPP_STD_VER > 14
483
484template <bool _CanCopy, bool _CanMove>
485struct __sfinae_ctor_base {};
486template <>
487struct __sfinae_ctor_base<false, false> {
488  __sfinae_ctor_base() = default;
489  __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
490  __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
491  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
492  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
493};
494template <>
495struct __sfinae_ctor_base<true, false> {
496  __sfinae_ctor_base() = default;
497  __sfinae_ctor_base(__sfinae_ctor_base const&) = default;
498  __sfinae_ctor_base(__sfinae_ctor_base &&) = delete;
499  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
500  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
501};
502template <>
503struct __sfinae_ctor_base<false, true> {
504  __sfinae_ctor_base() = default;
505  __sfinae_ctor_base(__sfinae_ctor_base const&) = delete;
506  __sfinae_ctor_base(__sfinae_ctor_base &&) = default;
507  __sfinae_ctor_base& operator=(__sfinae_ctor_base const&) = default;
508  __sfinae_ctor_base& operator=(__sfinae_ctor_base&&) = default;
509};
510
511template <bool _CanCopy, bool _CanMove>
512struct __sfinae_assign_base {};
513template <>
514struct __sfinae_assign_base<false, false> {
515  __sfinae_assign_base() = default;
516  __sfinae_assign_base(__sfinae_assign_base const&) = default;
517  __sfinae_assign_base(__sfinae_assign_base &&) = default;
518  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
519  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
520};
521template <>
522struct __sfinae_assign_base<true, false> {
523  __sfinae_assign_base() = default;
524  __sfinae_assign_base(__sfinae_assign_base const&) = default;
525  __sfinae_assign_base(__sfinae_assign_base &&) = default;
526  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = default;
527  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = delete;
528};
529template <>
530struct __sfinae_assign_base<false, true> {
531  __sfinae_assign_base() = default;
532  __sfinae_assign_base(__sfinae_assign_base const&) = default;
533  __sfinae_assign_base(__sfinae_assign_base &&) = default;
534  __sfinae_assign_base& operator=(__sfinae_assign_base const&) = delete;
535  __sfinae_assign_base& operator=(__sfinae_assign_base&&) = default;
536};
537#endif // _LIBCPP_STD_VER > 14
538
539_LIBCPP_END_NAMESPACE_STD
540
541#endif  // _LIBCPP___TUPLE
542