1// -*- C++ -*-
2//===------------------------ type_traits ---------------------------------===//
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_TYPE_TRAITS
11#define _LIBCPP_TYPE_TRAITS
12
13/*
14    type_traits synopsis
15
16namespace std
17{
18
19    // helper class:
20    template <class T, T v> struct integral_constant;
21    typedef integral_constant<bool, true>  true_type;   // C++11
22    typedef integral_constant<bool, false> false_type;  // C++11
23
24    template <bool B>                                   // C++14
25    using bool_constant = integral_constant<bool, B>;   // C++14
26    typedef bool_constant<true> true_type;              // C++14
27    typedef bool_constant<false> false_type;            // C++14
28
29    // helper traits
30    template <bool, class T = void> struct enable_if;
31    template <bool, class T, class F> struct conditional;
32
33    // Primary classification traits:
34    template <class T> struct is_void;
35    template <class T> struct is_null_pointer;  // C++14
36    template <class T> struct is_integral;
37    template <class T> struct is_floating_point;
38    template <class T> struct is_array;
39    template <class T> struct is_pointer;
40    template <class T> struct is_lvalue_reference;
41    template <class T> struct is_rvalue_reference;
42    template <class T> struct is_member_object_pointer;
43    template <class T> struct is_member_function_pointer;
44    template <class T> struct is_enum;
45    template <class T> struct is_union;
46    template <class T> struct is_class;
47    template <class T> struct is_function;
48
49    // Secondary classification traits:
50    template <class T> struct is_reference;
51    template <class T> struct is_arithmetic;
52    template <class T> struct is_fundamental;
53    template <class T> struct is_member_pointer;
54    template <class T> struct is_scoped_enum; // C++2b
55    template <class T> struct is_scalar;
56    template <class T> struct is_object;
57    template <class T> struct is_compound;
58
59    // Const-volatile properties and transformations:
60    template <class T> struct is_const;
61    template <class T> struct is_volatile;
62    template <class T> struct remove_const;
63    template <class T> struct remove_volatile;
64    template <class T> struct remove_cv;
65    template <class T> struct add_const;
66    template <class T> struct add_volatile;
67    template <class T> struct add_cv;
68
69    // Reference transformations:
70    template <class T> struct remove_reference;
71    template <class T> struct add_lvalue_reference;
72    template <class T> struct add_rvalue_reference;
73
74    // Pointer transformations:
75    template <class T> struct remove_pointer;
76    template <class T> struct add_pointer;
77
78    template<class T> struct type_identity;                     // C++20
79    template<class T>
80      using type_identity_t = typename type_identity<T>::type;  // C++20
81
82    // Integral properties:
83    template <class T> struct is_signed;
84    template <class T> struct is_unsigned;
85    template <class T> struct make_signed;
86    template <class T> struct make_unsigned;
87
88    // Array properties and transformations:
89    template <class T> struct rank;
90    template <class T, unsigned I = 0> struct extent;
91    template <class T> struct remove_extent;
92    template <class T> struct remove_all_extents;
93
94    template <class T> struct is_bounded_array;                 // C++20
95    template <class T> struct is_unbounded_array;               // C++20
96
97    // Member introspection:
98    template <class T> struct is_pod;
99    template <class T> struct is_trivial;
100    template <class T> struct is_trivially_copyable;
101    template <class T> struct is_standard_layout;
102    template <class T> struct is_literal_type;
103    template <class T> struct is_empty;
104    template <class T> struct is_polymorphic;
105    template <class T> struct is_abstract;
106    template <class T> struct is_final; // C++14
107    template <class T> struct is_aggregate; // C++17
108
109    template <class T, class... Args> struct is_constructible;
110    template <class T>                struct is_default_constructible;
111    template <class T>                struct is_copy_constructible;
112    template <class T>                struct is_move_constructible;
113    template <class T, class U>       struct is_assignable;
114    template <class T>                struct is_copy_assignable;
115    template <class T>                struct is_move_assignable;
116    template <class T, class U>       struct is_swappable_with;       // C++17
117    template <class T>                struct is_swappable;            // C++17
118    template <class T>                struct is_destructible;
119
120    template <class T, class... Args> struct is_trivially_constructible;
121    template <class T>                struct is_trivially_default_constructible;
122    template <class T>                struct is_trivially_copy_constructible;
123    template <class T>                struct is_trivially_move_constructible;
124    template <class T, class U>       struct is_trivially_assignable;
125    template <class T>                struct is_trivially_copy_assignable;
126    template <class T>                struct is_trivially_move_assignable;
127    template <class T>                struct is_trivially_destructible;
128
129    template <class T, class... Args> struct is_nothrow_constructible;
130    template <class T>                struct is_nothrow_default_constructible;
131    template <class T>                struct is_nothrow_copy_constructible;
132    template <class T>                struct is_nothrow_move_constructible;
133    template <class T, class U>       struct is_nothrow_assignable;
134    template <class T>                struct is_nothrow_copy_assignable;
135    template <class T>                struct is_nothrow_move_assignable;
136    template <class T, class U>       struct is_nothrow_swappable_with; // C++17
137    template <class T>                struct is_nothrow_swappable;      // C++17
138    template <class T>                struct is_nothrow_destructible;
139
140    template <class T> struct has_virtual_destructor;
141
142    template<class T> struct has_unique_object_representations;         // C++17
143
144    // Relationships between types:
145    template <class T, class U> struct is_same;
146    template <class Base, class Derived> struct is_base_of;
147
148    template <class From, class To> struct is_convertible;
149    template <typename From, typename To> struct is_nothrow_convertible;                  // C++20
150    template <typename From, typename To> inline constexpr bool is_nothrow_convertible_v; // C++20
151
152    template <class Fn, class... ArgTypes> struct is_invocable;
153    template <class R, class Fn, class... ArgTypes> struct is_invocable_r;
154
155    template <class Fn, class... ArgTypes> struct is_nothrow_invocable;
156    template <class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r;
157
158    // Alignment properties and transformations:
159    template <class T> struct alignment_of;
160    template <size_t Len, size_t Align = most_stringent_alignment_requirement>
161        struct aligned_storage;
162    template <size_t Len, class... Types> struct aligned_union;
163    template <class T> struct remove_cvref; // C++20
164
165    template <class T> struct decay;
166    template <class... T> struct common_type;
167    template <class T> struct underlying_type;
168    template <class> class result_of; // undefined
169    template <class Fn, class... ArgTypes> class result_of<Fn(ArgTypes...)>;
170    template <class Fn, class... ArgTypes> struct invoke_result;  // C++17
171
172    // const-volatile modifications:
173    template <class T>
174      using remove_const_t    = typename remove_const<T>::type;  // C++14
175    template <class T>
176      using remove_volatile_t = typename remove_volatile<T>::type;  // C++14
177    template <class T>
178      using remove_cv_t       = typename remove_cv<T>::type;  // C++14
179    template <class T>
180      using add_const_t       = typename add_const<T>::type;  // C++14
181    template <class T>
182      using add_volatile_t    = typename add_volatile<T>::type;  // C++14
183    template <class T>
184      using add_cv_t          = typename add_cv<T>::type;  // C++14
185
186    // reference modifications:
187    template <class T>
188      using remove_reference_t     = typename remove_reference<T>::type;  // C++14
189    template <class T>
190      using add_lvalue_reference_t = typename add_lvalue_reference<T>::type;  // C++14
191    template <class T>
192      using add_rvalue_reference_t = typename add_rvalue_reference<T>::type;  // C++14
193
194    // sign modifications:
195    template <class T>
196      using make_signed_t   = typename make_signed<T>::type;  // C++14
197    template <class T>
198      using make_unsigned_t = typename make_unsigned<T>::type;  // C++14
199
200    // array modifications:
201    template <class T>
202      using remove_extent_t      = typename remove_extent<T>::type;  // C++14
203    template <class T>
204      using remove_all_extents_t = typename remove_all_extents<T>::type;  // C++14
205
206    template <class T>
207      inline constexpr bool is_bounded_array_v
208        = is_bounded_array<T>::value;                                     // C++20
209      inline constexpr bool is_unbounded_array_v
210        = is_unbounded_array<T>::value;                                   // C++20
211
212    // pointer modifications:
213    template <class T>
214      using remove_pointer_t = typename remove_pointer<T>::type;  // C++14
215    template <class T>
216      using add_pointer_t    = typename add_pointer<T>::type;  // C++14
217
218    // other transformations:
219    template <size_t Len, std::size_t Align=default-alignment>
220      using aligned_storage_t = typename aligned_storage<Len,Align>::type;  // C++14
221    template <std::size_t Len, class... Types>
222      using aligned_union_t   = typename aligned_union<Len,Types...>::type;  // C++14
223    template <class T>
224      using remove_cvref_t    = typename remove_cvref<T>::type;  // C++20
225    template <class T>
226      using decay_t           = typename decay<T>::type;  // C++14
227    template <bool b, class T=void>
228      using enable_if_t       = typename enable_if<b,T>::type;  // C++14
229    template <bool b, class T, class F>
230      using conditional_t     = typename conditional<b,T,F>::type;  // C++14
231    template <class... T>
232      using common_type_t     = typename common_type<T...>::type;  // C++14
233    template <class T>
234      using underlying_type_t = typename underlying_type<T>::type;  // C++14
235    template <class T>
236      using result_of_t       = typename result_of<T>::type;  // C++14
237    template <class Fn, class... ArgTypes>
238      using invoke_result_t   = typename invoke_result<Fn, ArgTypes...>::type;  // C++17
239
240    template <class...>
241      using void_t = void;   // C++17
242
243      // See C++14 20.10.4.1, primary type categories
244      template <class T> inline constexpr bool is_void_v
245        = is_void<T>::value;                                             // C++17
246      template <class T> inline constexpr bool is_null_pointer_v
247        = is_null_pointer<T>::value;                                     // C++17
248      template <class T> inline constexpr bool is_integral_v
249        = is_integral<T>::value;                                         // C++17
250      template <class T> inline constexpr bool is_floating_point_v
251        = is_floating_point<T>::value;                                   // C++17
252      template <class T> inline constexpr bool is_array_v
253        = is_array<T>::value;                                            // C++17
254      template <class T> inline constexpr bool is_pointer_v
255        = is_pointer<T>::value;                                          // C++17
256      template <class T> inline constexpr bool is_lvalue_reference_v
257        = is_lvalue_reference<T>::value;                                 // C++17
258      template <class T> inline constexpr bool is_rvalue_reference_v
259        = is_rvalue_reference<T>::value;                                 // C++17
260      template <class T> inline constexpr bool is_member_object_pointer_v
261        = is_member_object_pointer<T>::value;                            // C++17
262      template <class T> inline constexpr bool is_member_function_pointer_v
263        = is_member_function_pointer<T>::value;                          // C++17
264      template <class T> inline constexpr bool is_enum_v
265        = is_enum<T>::value;                                             // C++17
266      template <class T> inline constexpr bool is_union_v
267        = is_union<T>::value;                                            // C++17
268      template <class T> inline constexpr bool is_class_v
269        = is_class<T>::value;                                            // C++17
270      template <class T> inline constexpr bool is_function_v
271        = is_function<T>::value;                                         // C++17
272
273      // See C++14 20.10.4.2, composite type categories
274      template <class T> inline constexpr bool is_reference_v
275        = is_reference<T>::value;                                        // C++17
276      template <class T> inline constexpr bool is_arithmetic_v
277        = is_arithmetic<T>::value;                                       // C++17
278      template <class T> inline constexpr bool is_fundamental_v
279        = is_fundamental<T>::value;                                      // C++17
280      template <class T> inline constexpr bool is_object_v
281        = is_object<T>::value;                                           // C++17
282      template <class T> inline constexpr bool is_scalar_v
283        = is_scalar<T>::value;                                           // C++17
284      template <class T> inline constexpr bool is_compound_v
285        = is_compound<T>::value;                                         // C++17
286      template <class T> inline constexpr bool is_member_pointer_v
287        = is_member_pointer<T>::value;                                   // C++17
288      template <class T> inline constexpr bool is_scoped_enum_v
289        = is_scoped_enum<T>::value;                                      // C++2b
290
291      // See C++14 20.10.4.3, type properties
292      template <class T> inline constexpr bool is_const_v
293        = is_const<T>::value;                                            // C++17
294      template <class T> inline constexpr bool is_volatile_v
295        = is_volatile<T>::value;                                         // C++17
296      template <class T> inline constexpr bool is_trivial_v
297        = is_trivial<T>::value;                                          // C++17
298      template <class T> inline constexpr bool is_trivially_copyable_v
299        = is_trivially_copyable<T>::value;                               // C++17
300      template <class T> inline constexpr bool is_standard_layout_v
301        = is_standard_layout<T>::value;                                  // C++17
302      template <class T> inline constexpr bool is_pod_v
303        = is_pod<T>::value;                                              // C++17
304      template <class T> inline constexpr bool is_literal_type_v
305        = is_literal_type<T>::value;                                     // C++17
306      template <class T> inline constexpr bool is_empty_v
307        = is_empty<T>::value;                                            // C++17
308      template <class T> inline constexpr bool is_polymorphic_v
309        = is_polymorphic<T>::value;                                      // C++17
310      template <class T> inline constexpr bool is_abstract_v
311        = is_abstract<T>::value;                                         // C++17
312      template <class T> inline constexpr bool is_final_v
313        = is_final<T>::value;                                            // C++17
314      template <class T> inline constexpr bool is_aggregate_v
315        = is_aggregate<T>::value;                                        // C++17
316      template <class T> inline constexpr bool is_signed_v
317        = is_signed<T>::value;                                           // C++17
318      template <class T> inline constexpr bool is_unsigned_v
319        = is_unsigned<T>::value;                                         // C++17
320      template <class T, class... Args> inline constexpr bool is_constructible_v
321        = is_constructible<T, Args...>::value;                           // C++17
322      template <class T> inline constexpr bool is_default_constructible_v
323        = is_default_constructible<T>::value;                            // C++17
324      template <class T> inline constexpr bool is_copy_constructible_v
325        = is_copy_constructible<T>::value;                               // C++17
326      template <class T> inline constexpr bool is_move_constructible_v
327        = is_move_constructible<T>::value;                               // C++17
328      template <class T, class U> inline constexpr bool is_assignable_v
329        = is_assignable<T, U>::value;                                    // C++17
330      template <class T> inline constexpr bool is_copy_assignable_v
331        = is_copy_assignable<T>::value;                                  // C++17
332      template <class T> inline constexpr bool is_move_assignable_v
333        = is_move_assignable<T>::value;                                  // C++17
334      template <class T, class U> inline constexpr bool is_swappable_with_v
335        = is_swappable_with<T, U>::value;                                // C++17
336      template <class T> inline constexpr bool is_swappable_v
337        = is_swappable<T>::value;                                        // C++17
338      template <class T> inline constexpr bool is_destructible_v
339        = is_destructible<T>::value;                                     // C++17
340      template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
341        = is_trivially_constructible<T, Args...>::value;                 // C++17
342      template <class T> inline constexpr bool is_trivially_default_constructible_v
343        = is_trivially_default_constructible<T>::value;                  // C++17
344      template <class T> inline constexpr bool is_trivially_copy_constructible_v
345        = is_trivially_copy_constructible<T>::value;                     // C++17
346      template <class T> inline constexpr bool is_trivially_move_constructible_v
347        = is_trivially_move_constructible<T>::value;                     // C++17
348      template <class T, class U> inline constexpr bool is_trivially_assignable_v
349        = is_trivially_assignable<T, U>::value;                          // C++17
350      template <class T> inline constexpr bool is_trivially_copy_assignable_v
351        = is_trivially_copy_assignable<T>::value;                        // C++17
352      template <class T> inline constexpr bool is_trivially_move_assignable_v
353        = is_trivially_move_assignable<T>::value;                        // C++17
354      template <class T> inline constexpr bool is_trivially_destructible_v
355        = is_trivially_destructible<T>::value;                           // C++17
356      template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
357        = is_nothrow_constructible<T, Args...>::value;                   // C++17
358      template <class T> inline constexpr bool is_nothrow_default_constructible_v
359        = is_nothrow_default_constructible<T>::value;                    // C++17
360      template <class T> inline constexpr bool is_nothrow_copy_constructible_v
361        = is_nothrow_copy_constructible<T>::value;                       // C++17
362      template <class T> inline constexpr bool is_nothrow_move_constructible_v
363        = is_nothrow_move_constructible<T>::value;                       // C++17
364      template <class T, class U> inline constexpr bool is_nothrow_assignable_v
365        = is_nothrow_assignable<T, U>::value;                            // C++17
366      template <class T> inline constexpr bool is_nothrow_copy_assignable_v
367        = is_nothrow_copy_assignable<T>::value;                          // C++17
368      template <class T> inline constexpr bool is_nothrow_move_assignable_v
369        = is_nothrow_move_assignable<T>::value;                          // C++17
370      template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
371        = is_nothrow_swappable_with<T, U>::value;                       // C++17
372      template <class T> inline constexpr bool is_nothrow_swappable_v
373        = is_nothrow_swappable<T>::value;                               // C++17
374      template <class T> inline constexpr bool is_nothrow_destructible_v
375        = is_nothrow_destructible<T>::value;                             // C++17
376      template <class T> inline constexpr bool has_virtual_destructor_v
377        = has_virtual_destructor<T>::value;                              // C++17
378      template<class T> inline constexpr bool has_unique_object_representations_v // C++17
379        = has_unique_object_representations<T>::value;
380
381      // See C++14 20.10.5, type property queries
382      template <class T> inline constexpr size_t alignment_of_v
383        = alignment_of<T>::value;                                        // C++17
384      template <class T> inline constexpr size_t rank_v
385        = rank<T>::value;                                                // C++17
386      template <class T, unsigned I = 0> inline constexpr size_t extent_v
387        = extent<T, I>::value;                                           // C++17
388
389      // See C++14 20.10.6, type relations
390      template <class T, class U> inline constexpr bool is_same_v
391        = is_same<T, U>::value;                                          // C++17
392      template <class Base, class Derived> inline constexpr bool is_base_of_v
393        = is_base_of<Base, Derived>::value;                              // C++17
394      template <class From, class To> inline constexpr bool is_convertible_v
395        = is_convertible<From, To>::value;                               // C++17
396      template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
397        = is_invocable<Fn, ArgTypes...>::value;                          // C++17
398      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
399        = is_invocable_r<R, Fn, ArgTypes...>::value;                     // C++17
400      template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
401        = is_nothrow_invocable<Fn, ArgTypes...>::value;                  // C++17
402      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
403        = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;             // C++17
404
405      // [meta.logical], logical operator traits:
406      template<class... B> struct conjunction;                           // C++17
407      template<class... B>
408        inline constexpr bool conjunction_v = conjunction<B...>::value;  // C++17
409      template<class... B> struct disjunction;                           // C++17
410      template<class... B>
411        inline constexpr bool disjunction_v = disjunction<B...>::value;  // C++17
412      template<class B> struct negation;                                 // C++17
413      template<class B>
414        inline constexpr bool negation_v = negation<B>::value;           // C++17
415
416}
417
418*/
419#include <__config>
420#include <cstddef>
421#include <version>
422
423#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
424#pragma GCC system_header
425#endif
426
427_LIBCPP_BEGIN_NAMESPACE_STD
428
429template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS pair;
430template <class _Tp> class _LIBCPP_TEMPLATE_VIS reference_wrapper;
431template <class _Tp> struct _LIBCPP_TEMPLATE_VIS hash;
432
433template <class _Tp, _Tp __v>
434struct _LIBCPP_TEMPLATE_VIS integral_constant
435{
436  static _LIBCPP_CONSTEXPR const _Tp      value = __v;
437  typedef _Tp               value_type;
438  typedef integral_constant type;
439  _LIBCPP_INLINE_VISIBILITY
440  _LIBCPP_CONSTEXPR operator value_type() const _NOEXCEPT {return value;}
441#if _LIBCPP_STD_VER > 11
442  _LIBCPP_INLINE_VISIBILITY
443  constexpr value_type operator ()() const _NOEXCEPT {return value;}
444#endif
445};
446
447template <class _Tp, _Tp __v>
448_LIBCPP_CONSTEXPR const _Tp integral_constant<_Tp, __v>::value;
449
450#if _LIBCPP_STD_VER > 14
451template <bool __b>
452using bool_constant = integral_constant<bool, __b>;
453#define _LIBCPP_BOOL_CONSTANT(__b) bool_constant<(__b)>
454#else
455#define _LIBCPP_BOOL_CONSTANT(__b) integral_constant<bool,(__b)>
456#endif
457
458typedef _LIBCPP_BOOL_CONSTANT(true)  true_type;
459typedef _LIBCPP_BOOL_CONSTANT(false) false_type;
460
461template <bool _Val>
462using _BoolConstant _LIBCPP_NODEBUG_TYPE = integral_constant<bool, _Val>;
463
464template <bool> struct _MetaBase;
465template <>
466struct _MetaBase<true> {
467  template <class _Tp, class _Up>
468  using _SelectImpl _LIBCPP_NODEBUG_TYPE = _Tp;
469  template <template <class...> class _FirstFn, template <class...> class, class ..._Args>
470  using _SelectApplyImpl _LIBCPP_NODEBUG_TYPE = _FirstFn<_Args...>;
471  template <class _First, class...>
472  using _FirstImpl _LIBCPP_NODEBUG_TYPE = _First;
473  template <class, class _Second, class...>
474  using _SecondImpl _LIBCPP_NODEBUG_TYPE = _Second;
475  template <class _Tp = void>
476  using _EnableIfImpl _LIBCPP_NODEBUG_TYPE = _Tp;
477  template <class _Result, class _First, class ..._Rest>
478  using _OrImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value != true && sizeof...(_Rest) != 0>::template _OrImpl<_First, _Rest...>;
479  template <class _Result, class _First, class ..._Rest>
480  using _AndImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value == true && sizeof...(_Rest) != 0>::template _AndImpl<_First, _Rest...>;
481};
482
483template <>
484struct _MetaBase<false> {
485  template <class _Tp, class _Up>
486  using _SelectImpl _LIBCPP_NODEBUG_TYPE = _Up;
487  template <template <class...> class, template <class...> class _SecondFn, class ..._Args>
488  using _SelectApplyImpl _LIBCPP_NODEBUG_TYPE = _SecondFn<_Args...>;
489  template <class _Result, class ...>
490  using _OrImpl _LIBCPP_NODEBUG_TYPE = _Result;
491  template <class _Result, class ...>
492  using _AndImpl _LIBCPP_NODEBUG_TYPE = _Result;
493};
494template <bool _Cond, class _Ret = void>
495using _EnableIf _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_Cond>::template _EnableIfImpl<_Ret>;
496template <bool _Cond, class _IfRes, class _ElseRes>
497using _If _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_Cond>::template _SelectImpl<_IfRes, _ElseRes>;
498template <class ..._Rest>
499using _Or _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::template _OrImpl<false_type, _Rest...>;
500template <class ..._Rest>
501using _And _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::template _AndImpl<true_type, _Rest...>;
502template <class _Pred>
503struct _Not : _BoolConstant<!_Pred::value> {};
504template <class ..._Args>
505using _FirstType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 1)>::template _FirstImpl<_Args...>;
506template <class ..._Args>
507using _SecondType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 2)>::template _SecondImpl<_Args...>;
508
509template <template <class...> class _Func, class ..._Args>
510struct _Lazy : _Func<_Args...> {};
511
512// Member detector base
513
514template <template <class...> class _Templ, class ..._Args, class = _Templ<_Args...> >
515true_type __sfinae_test_impl(int);
516template <template <class...> class, class ...>
517false_type __sfinae_test_impl(...);
518
519template <template <class ...> class _Templ, class ..._Args>
520using _IsValidExpansion _LIBCPP_NODEBUG_TYPE = decltype(__sfinae_test_impl<_Templ, _Args...>(0));
521
522template <class>
523struct __void_t { typedef void type; };
524
525template <class _Tp>
526struct __identity { typedef _Tp type; };
527
528template <class _Tp>
529using __identity_t _LIBCPP_NODEBUG_TYPE = typename __identity<_Tp>::type;
530
531template <class _Tp, bool>
532struct _LIBCPP_TEMPLATE_VIS __dependent_type : public _Tp {};
533
534
535template <bool _Bp, class _If, class _Then>
536    struct _LIBCPP_TEMPLATE_VIS conditional {typedef _If type;};
537template <class _If, class _Then>
538    struct _LIBCPP_TEMPLATE_VIS conditional<false, _If, _Then> {typedef _Then type;};
539
540#if _LIBCPP_STD_VER > 11
541template <bool _Bp, class _If, class _Then> using conditional_t = typename conditional<_Bp, _If, _Then>::type;
542#endif
543
544template <bool, class _Tp = void> struct _LIBCPP_TEMPLATE_VIS enable_if {};
545template <class _Tp> struct _LIBCPP_TEMPLATE_VIS enable_if<true, _Tp> {typedef _Tp type;};
546
547#if _LIBCPP_STD_VER > 11
548template <bool _Bp, class _Tp = void> using enable_if_t = typename enable_if<_Bp, _Tp>::type;
549#endif
550
551// is_same
552
553#if __has_keyword(__is_same)
554
555template <class _Tp, class _Up>
556struct _LIBCPP_TEMPLATE_VIS is_same : _BoolConstant<__is_same(_Tp, _Up)> { };
557
558#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
559template <class _Tp, class _Up>
560_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_same_v = __is_same(_Tp, _Up);
561#endif
562
563#else
564
565template <class _Tp, class _Up> struct _LIBCPP_TEMPLATE_VIS is_same           : public false_type {};
566template <class _Tp>            struct _LIBCPP_TEMPLATE_VIS is_same<_Tp, _Tp> : public true_type {};
567
568#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
569template <class _Tp, class _Up>
570_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_same_v
571    = is_same<_Tp, _Up>::value;
572#endif
573
574#endif // __is_same
575
576template <class _Tp, class _Up>
577using _IsSame = _BoolConstant<
578#ifdef __clang__
579    __is_same(_Tp, _Up)
580#else
581    _VSTD::is_same<_Tp, _Up>::value
582#endif
583>;
584
585template <class _Tp, class _Up>
586using _IsNotSame = _BoolConstant<
587#ifdef __clang__
588    !__is_same(_Tp, _Up)
589#else
590    !_VSTD::is_same<_Tp, _Up>::value
591#endif
592>;
593
594
595template <class _Tp>
596using __test_for_primary_template = _EnableIf<
597    _IsSame<_Tp, typename _Tp::__primary_template>::value
598  >;
599template <class _Tp>
600using __is_primary_template = _IsValidExpansion<
601    __test_for_primary_template, _Tp
602  >;
603
604struct __two {char __lx[2];};
605
606// helper class:
607
608// is_const
609
610#if __has_keyword(__is_const)
611
612template <class _Tp>
613struct _LIBCPP_TEMPLATE_VIS is_const : _BoolConstant<__is_const(_Tp)> { };
614
615#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
616template <class _Tp>
617_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_const_v = __is_const(_Tp);
618#endif
619
620#else
621
622template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const            : public false_type {};
623template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const<_Tp const> : public true_type {};
624
625#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
626template <class _Tp>
627_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_const_v
628    = is_const<_Tp>::value;
629#endif
630
631#endif // __has_keyword(__is_const)
632
633// is_volatile
634
635#if __has_keyword(__is_volatile)
636
637template <class _Tp>
638struct _LIBCPP_TEMPLATE_VIS is_volatile : _BoolConstant<__is_volatile(_Tp)> { };
639
640#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
641template <class _Tp>
642_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_volatile_v = __is_volatile(_Tp);
643#endif
644
645#else
646
647template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile               : public false_type {};
648template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_volatile<_Tp volatile> : public true_type {};
649
650#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
651template <class _Tp>
652_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_volatile_v
653    = is_volatile<_Tp>::value;
654#endif
655
656#endif // __has_keyword(__is_volatile)
657
658// remove_const
659
660#if __has_keyword(__remove_const)
661
662template <class _Tp>
663struct _LIBCPP_TEMPLATE_VIS remove_const {typedef __remove_const(_Tp) type;};
664
665#if _LIBCPP_STD_VER > 11
666template <class _Tp> using remove_const_t = __remove_const(_Tp);
667#endif
668
669#else
670
671template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const            {typedef _Tp type;};
672template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_const<const _Tp> {typedef _Tp type;};
673#if _LIBCPP_STD_VER > 11
674template <class _Tp> using remove_const_t = typename remove_const<_Tp>::type;
675#endif
676
677#endif // __has_keyword(__remove_const)
678
679// remove_volatile
680
681#if __has_keyword(__remove_volatile)
682
683template <class _Tp>
684struct _LIBCPP_TEMPLATE_VIS remove_volatile {typedef __remove_volatile(_Tp) type;};
685
686#if _LIBCPP_STD_VER > 11
687template <class _Tp> using remove_volatile_t = __remove_volatile(_Tp);
688#endif
689
690#else
691
692template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile               {typedef _Tp type;};
693template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_volatile<volatile _Tp> {typedef _Tp type;};
694#if _LIBCPP_STD_VER > 11
695template <class _Tp> using remove_volatile_t = typename remove_volatile<_Tp>::type;
696#endif
697
698#endif // __has_keyword(__remove_volatile)
699
700// remove_cv
701
702#if __has_keyword(__remove_cv)
703
704template <class _Tp>
705struct _LIBCPP_TEMPLATE_VIS remove_cv {typedef __remove_cv(_Tp) type;};
706
707#if _LIBCPP_STD_VER > 11
708template <class _Tp> using remove_cv_t = __remove_cv(_Tp);
709#endif
710
711#else
712
713template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_cv
714{typedef typename remove_volatile<typename remove_const<_Tp>::type>::type type;};
715#if _LIBCPP_STD_VER > 11
716template <class _Tp> using remove_cv_t = typename remove_cv<_Tp>::type;
717#endif
718
719#endif // __has_keyword(__remove_cv)
720
721// is_void
722
723#if __has_keyword(__is_void)
724
725template <class _Tp>
726struct _LIBCPP_TEMPLATE_VIS is_void : _BoolConstant<__is_void(_Tp)> { };
727
728#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
729template <class _Tp>
730_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_void_v = __is_void(_Tp);
731#endif
732
733#else
734
735template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_void
736    : public is_same<typename remove_cv<_Tp>::type, void> {};
737
738#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
739template <class _Tp>
740_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_void_v
741    = is_void<_Tp>::value;
742#endif
743
744#endif // __has_keyword(__is_void)
745
746// __is_nullptr_t
747
748template <class _Tp> struct __is_nullptr_t_impl       : public false_type {};
749template <>          struct __is_nullptr_t_impl<nullptr_t> : public true_type {};
750
751template <class _Tp> struct _LIBCPP_TEMPLATE_VIS __is_nullptr_t
752    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
753
754#if _LIBCPP_STD_VER > 11
755template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_null_pointer
756    : public __is_nullptr_t_impl<typename remove_cv<_Tp>::type> {};
757
758#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
759template <class _Tp>
760_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_null_pointer_v
761    = is_null_pointer<_Tp>::value;
762#endif
763#endif // _LIBCPP_STD_VER > 11
764
765// is_integral
766
767#if __has_keyword(__is_integral)
768
769template <class _Tp>
770struct _LIBCPP_TEMPLATE_VIS is_integral : _BoolConstant<__is_integral(_Tp)> { };
771
772#if _LIBCPP_STD_VER > 14
773template <class _Tp>
774_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_integral_v = __is_integral(_Tp);
775#endif
776
777#else
778
779template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_integral
780    : public _BoolConstant<__libcpp_is_integral<typename remove_cv<_Tp>::type>::value> {};
781
782#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
783template <class _Tp>
784_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_integral_v
785    = is_integral<_Tp>::value;
786#endif
787
788#endif // __has_keyword(__is_integral)
789
790// is_floating_point
791
792template <class _Tp> struct __libcpp_is_floating_point              : public false_type {};
793template <>          struct __libcpp_is_floating_point<float>       : public true_type {};
794template <>          struct __libcpp_is_floating_point<double>      : public true_type {};
795template <>          struct __libcpp_is_floating_point<long double> : public true_type {};
796
797template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_floating_point
798    : public __libcpp_is_floating_point<typename remove_cv<_Tp>::type> {};
799
800#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
801template <class _Tp>
802_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_floating_point_v
803    = is_floating_point<_Tp>::value;
804#endif
805
806// is_array
807
808#if __has_keyword(__is_array)
809
810template <class _Tp>
811struct _LIBCPP_TEMPLATE_VIS is_array : _BoolConstant<__is_array(_Tp)> { };
812
813#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
814template <class _Tp>
815_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_array_v = __is_array(_Tp);
816#endif
817
818#else
819
820template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array
821    : public false_type {};
822template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[]>
823    : public true_type {};
824template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[_Np]>
825    : public true_type {};
826
827#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
828template <class _Tp>
829_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_array_v
830    = is_array<_Tp>::value;
831#endif
832
833#endif // __has_keyword(__is_array)
834
835// is_pointer
836
837// Before Clang 11 / AppleClang 12.0.5, __is_pointer didn't work for Objective-C types.
838#if __has_keyword(__is_pointer) &&                                             \
839    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1100) &&               \
840    !(defined(_LIBCPP_APPLE_CLANG_VER) && _LIBCPP_APPLE_CLANG_VER < 1205)
841
842template<class _Tp>
843struct _LIBCPP_TEMPLATE_VIS is_pointer : _BoolConstant<__is_pointer(_Tp)> { };
844
845#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
846template <class _Tp>
847_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_pointer_v = __is_pointer(_Tp);
848#endif
849
850#else // __has_keyword(__is_pointer)
851
852template <class _Tp> struct __libcpp_is_pointer       : public false_type {};
853template <class _Tp> struct __libcpp_is_pointer<_Tp*> : public true_type {};
854
855template <class _Tp> struct __libcpp_remove_objc_qualifiers { typedef _Tp type; };
856#if defined(_LIBCPP_HAS_OBJC_ARC)
857template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __strong> { typedef _Tp type; };
858template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __weak> { typedef _Tp type; };
859template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __autoreleasing> { typedef _Tp type; };
860template <class _Tp> struct __libcpp_remove_objc_qualifiers<_Tp __unsafe_unretained> { typedef _Tp type; };
861#endif
862
863template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pointer
864    : public __libcpp_is_pointer<typename __libcpp_remove_objc_qualifiers<typename remove_cv<_Tp>::type>::type> {};
865
866#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
867template <class _Tp>
868_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_pointer_v
869    = is_pointer<_Tp>::value;
870#endif
871
872#endif // __has_keyword(__is_pointer)
873
874// is_reference
875
876#if __has_keyword(__is_lvalue_reference) && \
877    __has_keyword(__is_rvalue_reference) && \
878    __has_keyword(__is_reference)
879
880template<class _Tp>
881struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference : _BoolConstant<__is_lvalue_reference(_Tp)> { };
882
883template<class _Tp>
884struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference : _BoolConstant<__is_rvalue_reference(_Tp)> { };
885
886template<class _Tp>
887struct _LIBCPP_TEMPLATE_VIS is_reference : _BoolConstant<__is_reference(_Tp)> { };
888
889#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
890template <class _Tp>
891_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_reference_v = __is_reference(_Tp);
892
893template <class _Tp>
894_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_lvalue_reference_v = __is_lvalue_reference(_Tp);
895
896template <class _Tp>
897_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_rvalue_reference_v = __is_rvalue_reference(_Tp);
898#endif
899
900#else // __has_keyword(__is_lvalue_reference) && etc...
901
902template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference       : public false_type {};
903template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_lvalue_reference<_Tp&> : public true_type {};
904
905template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference        : public false_type {};
906template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_rvalue_reference<_Tp&&> : public true_type {};
907
908template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference        : public false_type {};
909template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&>  : public true_type {};
910template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_reference<_Tp&&> : public true_type {};
911
912#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
913template <class _Tp>
914_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_reference_v
915    = is_reference<_Tp>::value;
916
917template <class _Tp>
918_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_lvalue_reference_v
919    = is_lvalue_reference<_Tp>::value;
920
921template <class _Tp>
922_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_rvalue_reference_v
923    = is_rvalue_reference<_Tp>::value;
924#endif
925
926#endif // __has_keyword(__is_lvalue_reference) && etc...
927
928// is_union
929
930#if __has_feature(is_union) || defined(_LIBCPP_COMPILER_GCC)
931
932template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
933    : public integral_constant<bool, __is_union(_Tp)> {};
934
935#else
936
937template <class _Tp> struct __libcpp_union : public false_type {};
938template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_union
939    : public __libcpp_union<typename remove_cv<_Tp>::type> {};
940
941#endif
942
943#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
944template <class _Tp>
945_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_union_v
946    = is_union<_Tp>::value;
947#endif
948
949// is_class
950
951#if __has_feature(is_class) || defined(_LIBCPP_COMPILER_GCC)
952
953template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
954    : public integral_constant<bool, __is_class(_Tp)> {};
955
956#else
957
958namespace __is_class_imp
959{
960template <class _Tp> char  __test(int _Tp::*);
961template <class _Tp> __two __test(...);
962}
963
964template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_class
965    : public integral_constant<bool, sizeof(__is_class_imp::__test<_Tp>(0)) == 1 && !is_union<_Tp>::value> {};
966
967#endif
968
969#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
970template <class _Tp>
971_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_class_v
972    = is_class<_Tp>::value;
973#endif
974
975// is_function
976
977template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_function
978    : public _BoolConstant<
979#ifdef __clang__
980    __is_function(_Tp)
981#else
982 !(is_reference<_Tp>::value || is_const<const _Tp>::value)
983#endif
984    > {};
985
986
987#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
988template <class _Tp>
989_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_function_v
990    = is_function<_Tp>::value;
991#endif
992
993template <class _Tp> struct __libcpp_is_member_pointer {
994  enum {
995    __is_member = false,
996    __is_func = false,
997    __is_obj = false
998  };
999};
1000template <class _Tp, class _Up> struct __libcpp_is_member_pointer<_Tp _Up::*> {
1001  enum {
1002    __is_member = true,
1003    __is_func = is_function<_Tp>::value,
1004    __is_obj = !__is_func,
1005  };
1006};
1007
1008#if __has_keyword(__is_member_function_pointer)
1009
1010template<class _Tp>
1011struct _LIBCPP_TEMPLATE_VIS is_member_function_pointer
1012    : _BoolConstant<__is_member_function_pointer(_Tp)> { };
1013
1014#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1015template <class _Tp>
1016_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_function_pointer_v
1017    = __is_member_function_pointer(_Tp);
1018#endif
1019
1020#else // __has_keyword(__is_member_function_pointer)
1021
1022template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_function_pointer
1023    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_func > {};
1024
1025#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1026template <class _Tp>
1027_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_function_pointer_v
1028    = is_member_function_pointer<_Tp>::value;
1029#endif
1030
1031#endif // __has_keyword(__is_member_function_pointer)
1032
1033// is_member_pointer
1034
1035#if __has_keyword(__is_member_pointer)
1036
1037template<class _Tp>
1038struct _LIBCPP_TEMPLATE_VIS is_member_pointer : _BoolConstant<__is_member_pointer(_Tp)> { };
1039
1040#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1041template <class _Tp>
1042_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_pointer_v = __is_member_pointer(_Tp);
1043#endif
1044
1045#else // __has_keyword(__is_member_pointer)
1046
1047template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_pointer
1048 : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_member > {};
1049
1050#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1051template <class _Tp>
1052_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_pointer_v
1053    = is_member_pointer<_Tp>::value;
1054#endif
1055
1056#endif // __has_keyword(__is_member_pointer)
1057
1058// is_member_object_pointer
1059
1060#if __has_keyword(__is_member_object_pointer)
1061
1062template<class _Tp>
1063struct _LIBCPP_TEMPLATE_VIS is_member_object_pointer
1064    : _BoolConstant<__is_member_object_pointer(_Tp)> { };
1065
1066#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1067template <class _Tp>
1068_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_object_pointer_v
1069    = __is_member_object_pointer(_Tp);
1070#endif
1071
1072#else // __has_keyword(__is_member_object_pointer)
1073
1074template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_member_object_pointer
1075    : public _BoolConstant< __libcpp_is_member_pointer<typename remove_cv<_Tp>::type>::__is_obj >  {};
1076
1077#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1078template <class _Tp>
1079_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_member_object_pointer_v
1080    = is_member_object_pointer<_Tp>::value;
1081#endif
1082
1083#endif // __has_keyword(__is_member_object_pointer)
1084
1085// is_enum
1086
1087#if __has_feature(is_enum) || defined(_LIBCPP_COMPILER_GCC)
1088
1089template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
1090    : public integral_constant<bool, __is_enum(_Tp)> {};
1091
1092#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1093template <class _Tp>
1094_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_enum_v = __is_enum(_Tp);
1095#endif
1096
1097#else
1098
1099template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_enum
1100    : public integral_constant<bool, !is_void<_Tp>::value             &&
1101                                     !is_integral<_Tp>::value         &&
1102                                     !is_floating_point<_Tp>::value   &&
1103                                     !is_array<_Tp>::value            &&
1104                                     !is_pointer<_Tp>::value          &&
1105                                     !is_reference<_Tp>::value        &&
1106                                     !is_member_pointer<_Tp>::value   &&
1107                                     !is_union<_Tp>::value            &&
1108                                     !is_class<_Tp>::value            &&
1109                                     !is_function<_Tp>::value         > {};
1110
1111#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1112template <class _Tp>
1113_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_enum_v
1114    = is_enum<_Tp>::value;
1115#endif
1116
1117#endif // __has_feature(is_enum) || defined(_LIBCPP_COMPILER_GCC)
1118
1119// is_arithmetic
1120
1121
1122template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_arithmetic
1123    : public integral_constant<bool, is_integral<_Tp>::value      ||
1124                                     is_floating_point<_Tp>::value> {};
1125
1126#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1127template <class _Tp>
1128_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_arithmetic_v
1129    = is_arithmetic<_Tp>::value;
1130#endif
1131
1132// is_fundamental
1133
1134// Before Clang 10, __is_fundamental didn't work for nullptr_t.
1135// In C++03 nullptr_t is library-provided but must still count as "fundamental."
1136#if __has_keyword(__is_fundamental) &&                                         \
1137    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1000) &&               \
1138    !defined(_LIBCPP_CXX03_LANG)
1139
1140template<class _Tp>
1141struct _LIBCPP_TEMPLATE_VIS is_fundamental : _BoolConstant<__is_fundamental(_Tp)> { };
1142
1143#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1144template <class _Tp>
1145_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_fundamental_v = __is_fundamental(_Tp);
1146#endif
1147
1148#else // __has_keyword(__is_fundamental)
1149
1150template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_fundamental
1151    : public integral_constant<bool, is_void<_Tp>::value        ||
1152                                     __is_nullptr_t<_Tp>::value ||
1153                                     is_arithmetic<_Tp>::value> {};
1154
1155#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1156template <class _Tp>
1157_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_fundamental_v
1158    = is_fundamental<_Tp>::value;
1159#endif
1160
1161#endif // __has_keyword(__is_fundamental)
1162
1163// is_scalar
1164
1165// In C++03 nullptr_t is library-provided but must still count as "scalar."
1166#if __has_keyword(__is_scalar) && !defined(_LIBCPP_CXX03_LANG)
1167
1168template<class _Tp>
1169struct _LIBCPP_TEMPLATE_VIS is_scalar : _BoolConstant<__is_scalar(_Tp)> { };
1170
1171#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1172template <class _Tp>
1173_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_scalar_v = __is_scalar(_Tp);
1174#endif
1175
1176#else // __has_keyword(__is_scalar)
1177
1178template <class _Tp> struct __is_block : false_type {};
1179#if defined(_LIBCPP_HAS_EXTENSION_BLOCKS)
1180template <class _Rp, class ..._Args> struct __is_block<_Rp (^)(_Args...)> : true_type {};
1181#endif
1182
1183template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_scalar
1184    : public integral_constant<bool, is_arithmetic<_Tp>::value     ||
1185                                     is_member_pointer<_Tp>::value ||
1186                                     is_pointer<_Tp>::value        ||
1187                                     __is_nullptr_t<_Tp>::value    ||
1188                                     __is_block<_Tp>::value        ||
1189                                     is_enum<_Tp>::value           > {};
1190
1191template <> struct _LIBCPP_TEMPLATE_VIS is_scalar<nullptr_t> : public true_type {};
1192
1193#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1194template <class _Tp>
1195_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_scalar_v
1196    = is_scalar<_Tp>::value;
1197#endif
1198
1199#endif // __has_keyword(__is_scalar)
1200
1201// is_object
1202
1203#if __has_keyword(__is_object)
1204
1205template<class _Tp>
1206struct _LIBCPP_TEMPLATE_VIS is_object : _BoolConstant<__is_object(_Tp)> { };
1207
1208#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1209template <class _Tp>
1210_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_object_v = __is_object(_Tp);
1211#endif
1212
1213#else // __has_keyword(__is_object)
1214
1215template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_object
1216    : public integral_constant<bool, is_scalar<_Tp>::value ||
1217                                     is_array<_Tp>::value  ||
1218                                     is_union<_Tp>::value  ||
1219                                     is_class<_Tp>::value  > {};
1220
1221#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1222template <class _Tp>
1223_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_object_v
1224    = is_object<_Tp>::value;
1225#endif
1226
1227#endif // __has_keyword(__is_object)
1228
1229// is_compound
1230
1231// >= 11 because in C++03 nullptr isn't actually nullptr
1232#if __has_keyword(__is_compound) && !defined(_LIBCPP_CXX03_LANG)
1233
1234template<class _Tp>
1235struct _LIBCPP_TEMPLATE_VIS is_compound : _BoolConstant<__is_compound(_Tp)> { };
1236
1237#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1238template <class _Tp>
1239_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_compound_v = __is_compound(_Tp);
1240#endif
1241
1242#else // __has_keyword(__is_compound)
1243
1244template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_compound
1245    : public integral_constant<bool, !is_fundamental<_Tp>::value> {};
1246
1247#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1248template <class _Tp>
1249_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_compound_v
1250    = is_compound<_Tp>::value;
1251#endif
1252
1253#endif // __has_keyword(__is_compound)
1254
1255// __is_referenceable  [defns.referenceable]
1256
1257struct __is_referenceable_impl {
1258    template <class _Tp> static _Tp& __test(int);
1259    template <class _Tp> static __two __test(...);
1260};
1261
1262template <class _Tp>
1263struct __is_referenceable : integral_constant<bool,
1264    _IsNotSame<decltype(__is_referenceable_impl::__test<_Tp>(0)), __two>::value> {};
1265
1266
1267// add_const
1268
1269template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_const {
1270  typedef _LIBCPP_NODEBUG_TYPE const _Tp type;
1271};
1272
1273#if _LIBCPP_STD_VER > 11
1274template <class _Tp> using add_const_t = typename add_const<_Tp>::type;
1275#endif
1276
1277// add_volatile
1278
1279template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_volatile {
1280  typedef _LIBCPP_NODEBUG_TYPE volatile _Tp type;
1281};
1282
1283#if _LIBCPP_STD_VER > 11
1284template <class _Tp> using add_volatile_t = typename add_volatile<_Tp>::type;
1285#endif
1286
1287// add_cv
1288template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_cv {
1289  typedef _LIBCPP_NODEBUG_TYPE const volatile _Tp type;
1290};
1291
1292#if _LIBCPP_STD_VER > 11
1293template <class _Tp> using add_cv_t = typename add_cv<_Tp>::type;
1294#endif
1295
1296// remove_reference
1297
1298#if __has_keyword(__remove_reference)
1299
1300template<class _Tp>
1301struct _LIBCPP_TEMPLATE_VIS remove_reference { typedef __remove_reference(_Tp) type; };
1302
1303#else // __has_keyword(__remove_reference)
1304
1305template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference        {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1306template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&>  {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1307template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_reference<_Tp&&> {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1308
1309#if _LIBCPP_STD_VER > 11
1310template <class _Tp> using remove_reference_t = typename remove_reference<_Tp>::type;
1311#endif
1312
1313#endif // __has_keyword(__remove_reference)
1314
1315// add_lvalue_reference
1316
1317template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_lvalue_reference_impl            { typedef _LIBCPP_NODEBUG_TYPE _Tp  type; };
1318template <class _Tp                                       > struct __add_lvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG_TYPE _Tp& type; };
1319
1320template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_lvalue_reference
1321{typedef _LIBCPP_NODEBUG_TYPE typename  __add_lvalue_reference_impl<_Tp>::type type;};
1322
1323#if _LIBCPP_STD_VER > 11
1324template <class _Tp> using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1325#endif
1326
1327template <class _Tp, bool = __is_referenceable<_Tp>::value> struct __add_rvalue_reference_impl            { typedef _LIBCPP_NODEBUG_TYPE  _Tp   type; };
1328template <class _Tp                                       > struct __add_rvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG_TYPE  _Tp&& type; };
1329
1330template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_rvalue_reference
1331{typedef _LIBCPP_NODEBUG_TYPE  typename __add_rvalue_reference_impl<_Tp>::type type;};
1332
1333#if _LIBCPP_STD_VER > 11
1334template <class _Tp> using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1335#endif
1336
1337// Suppress deprecation notice for volatile-qualified return type resulting
1338// from volatile-qualified types _Tp.
1339_LIBCPP_SUPPRESS_DEPRECATED_PUSH
1340template <class _Tp> _Tp&& __declval(int);
1341template <class _Tp> _Tp   __declval(long);
1342_LIBCPP_SUPPRESS_DEPRECATED_POP
1343
1344template <class _Tp>
1345decltype(_VSTD::__declval<_Tp>(0))
1346declval() _NOEXCEPT;
1347
1348// __uncvref
1349
1350template <class _Tp>
1351struct __uncvref  {
1352    typedef _LIBCPP_NODEBUG_TYPE typename remove_cv<typename remove_reference<_Tp>::type>::type type;
1353};
1354
1355template <class _Tp>
1356struct __unconstref {
1357    typedef _LIBCPP_NODEBUG_TYPE typename remove_const<typename remove_reference<_Tp>::type>::type type;
1358};
1359
1360#ifndef _LIBCPP_CXX03_LANG
1361template <class _Tp>
1362using __uncvref_t _LIBCPP_NODEBUG_TYPE = typename __uncvref<_Tp>::type;
1363#endif
1364
1365// __is_same_uncvref
1366
1367template <class _Tp, class _Up>
1368struct __is_same_uncvref : _IsSame<typename __uncvref<_Tp>::type,
1369                                   typename __uncvref<_Up>::type> {};
1370
1371#if _LIBCPP_STD_VER > 17
1372// remove_cvref - same as __uncvref
1373template <class _Tp>
1374struct remove_cvref : public __uncvref<_Tp> {};
1375
1376template <class _Tp> using remove_cvref_t = typename remove_cvref<_Tp>::type;
1377#endif
1378
1379
1380struct __any
1381{
1382    __any(...);
1383};
1384
1385// remove_pointer
1386
1387template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer                      {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1388template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp*>                {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1389template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const>          {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1390template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* volatile>       {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1391template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer<_Tp* const volatile> {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1392
1393#if _LIBCPP_STD_VER > 11
1394template <class _Tp> using remove_pointer_t = typename remove_pointer<_Tp>::type;
1395#endif
1396
1397// add_pointer
1398
1399template <class _Tp,
1400        bool = __is_referenceable<_Tp>::value ||
1401                _IsSame<typename remove_cv<_Tp>::type, void>::value>
1402struct __add_pointer_impl
1403    {typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type* type;};
1404template <class _Tp> struct __add_pointer_impl<_Tp, false>
1405    {typedef _LIBCPP_NODEBUG_TYPE _Tp type;};
1406
1407template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_pointer
1408    {typedef _LIBCPP_NODEBUG_TYPE typename __add_pointer_impl<_Tp>::type type;};
1409
1410#if _LIBCPP_STD_VER > 11
1411template <class _Tp> using add_pointer_t = typename add_pointer<_Tp>::type;
1412#endif
1413
1414// type_identity
1415#if _LIBCPP_STD_VER > 17
1416template<class _Tp> struct type_identity { typedef _Tp type; };
1417template<class _Tp> using type_identity_t = typename type_identity<_Tp>::type;
1418#endif
1419
1420// is_signed
1421
1422// Before Clang 10, __is_signed didn't work for floating-point types or enums.
1423#if __has_keyword(__is_signed) &&                                              \
1424    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1000)
1425
1426template<class _Tp>
1427struct _LIBCPP_TEMPLATE_VIS is_signed : _BoolConstant<__is_signed(_Tp)> { };
1428
1429#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1430template <class _Tp>
1431_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_signed_v = __is_signed(_Tp);
1432#endif
1433
1434#else // __has_keyword(__is_signed)
1435
1436template <class _Tp, bool = is_integral<_Tp>::value>
1437struct __libcpp_is_signed_impl : public _LIBCPP_BOOL_CONSTANT(_Tp(-1) < _Tp(0)) {};
1438
1439template <class _Tp>
1440struct __libcpp_is_signed_impl<_Tp, false> : public true_type {};  // floating point
1441
1442template <class _Tp, bool = is_arithmetic<_Tp>::value>
1443struct __libcpp_is_signed : public __libcpp_is_signed_impl<_Tp> {};
1444
1445template <class _Tp> struct __libcpp_is_signed<_Tp, false> : public false_type {};
1446
1447template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_signed : public __libcpp_is_signed<_Tp> {};
1448
1449#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1450template <class _Tp>
1451_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_signed_v
1452    = is_signed<_Tp>::value;
1453#endif
1454
1455#endif // __has_keyword(__is_signed)
1456
1457// is_unsigned
1458
1459// Before Clang 13, __is_unsigned returned true for enums with signed underlying type.
1460// No currently-released version of AppleClang contains the fixed intrinsic.
1461#if __has_keyword(__is_unsigned) &&                                            \
1462    !(defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER < 1300) &&               \
1463    !defined(_LIBCPP_APPLE_CLANG_VER)
1464
1465template<class _Tp>
1466struct _LIBCPP_TEMPLATE_VIS is_unsigned : _BoolConstant<__is_unsigned(_Tp)> { };
1467
1468#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1469template <class _Tp>
1470_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_unsigned_v = __is_unsigned(_Tp);
1471#endif
1472
1473#else // __has_keyword(__is_unsigned)
1474
1475template <class _Tp, bool = is_integral<_Tp>::value>
1476struct __libcpp_is_unsigned_impl : public _LIBCPP_BOOL_CONSTANT(_Tp(0) < _Tp(-1)) {};
1477
1478template <class _Tp>
1479struct __libcpp_is_unsigned_impl<_Tp, false> : public false_type {};  // floating point
1480
1481template <class _Tp, bool = is_arithmetic<_Tp>::value>
1482struct __libcpp_is_unsigned : public __libcpp_is_unsigned_impl<_Tp> {};
1483
1484template <class _Tp> struct __libcpp_is_unsigned<_Tp, false> : public false_type {};
1485
1486template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unsigned : public __libcpp_is_unsigned<_Tp> {};
1487
1488#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1489template <class _Tp>
1490_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_unsigned_v
1491    = is_unsigned<_Tp>::value;
1492#endif
1493
1494#endif // __has_keyword(__is_unsigned)
1495
1496// rank
1497
1498template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank
1499    : public integral_constant<size_t, 0> {};
1500template <class _Tp> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[]>
1501    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1502template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS rank<_Tp[_Np]>
1503    : public integral_constant<size_t, rank<_Tp>::value + 1> {};
1504
1505#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1506template <class _Tp>
1507_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t rank_v
1508    = rank<_Tp>::value;
1509#endif
1510
1511// extent
1512
1513#if __has_keyword(__array_extent)
1514
1515template<class _Tp, size_t _Dim = 0>
1516struct _LIBCPP_TEMPLATE_VIS extent
1517    : integral_constant<size_t, __array_extent(_Tp, _Dim)> { };
1518
1519#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1520template <class _Tp, unsigned _Ip = 0>
1521_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t extent_v = __array_extent(_Tp, _Ip);
1522#endif
1523
1524#else // __has_keyword(__array_extent)
1525
1526template <class _Tp, unsigned _Ip = 0> struct _LIBCPP_TEMPLATE_VIS extent
1527    : public integral_constant<size_t, 0> {};
1528template <class _Tp> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], 0>
1529    : public integral_constant<size_t, 0> {};
1530template <class _Tp, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[], _Ip>
1531    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1532template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], 0>
1533    : public integral_constant<size_t, _Np> {};
1534template <class _Tp, size_t _Np, unsigned _Ip> struct _LIBCPP_TEMPLATE_VIS extent<_Tp[_Np], _Ip>
1535    : public integral_constant<size_t, extent<_Tp, _Ip-1>::value> {};
1536
1537#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1538template <class _Tp, unsigned _Ip = 0>
1539_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t extent_v
1540    = extent<_Tp, _Ip>::value;
1541#endif
1542
1543#endif // __has_keyword(__array_extent)
1544
1545// remove_extent
1546
1547template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent
1548    {typedef _Tp type;};
1549template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[]>
1550    {typedef _Tp type;};
1551template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_extent<_Tp[_Np]>
1552    {typedef _Tp type;};
1553
1554#if _LIBCPP_STD_VER > 11
1555template <class _Tp> using remove_extent_t = typename remove_extent<_Tp>::type;
1556#endif
1557
1558// remove_all_extents
1559
1560template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents
1561    {typedef _Tp type;};
1562template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[]>
1563    {typedef typename remove_all_extents<_Tp>::type type;};
1564template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS remove_all_extents<_Tp[_Np]>
1565    {typedef typename remove_all_extents<_Tp>::type type;};
1566
1567#if _LIBCPP_STD_VER > 11
1568template <class _Tp> using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
1569#endif
1570
1571#if _LIBCPP_STD_VER > 17
1572// is_bounded_array
1573
1574template <class>                 struct _LIBCPP_TEMPLATE_VIS is_bounded_array           : false_type {};
1575template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_bounded_array<_Tp[_Np]> : true_type {};
1576
1577template <class _Tp>
1578_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR
1579bool is_bounded_array_v  = is_bounded_array<_Tp>::value;
1580
1581// is_unbounded_array
1582
1583template <class>     struct _LIBCPP_TEMPLATE_VIS is_unbounded_array        : false_type {};
1584template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_unbounded_array<_Tp[]> : true_type {};
1585
1586template <class _Tp>
1587_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR
1588bool is_unbounded_array_v  = is_unbounded_array<_Tp>::value;
1589#endif
1590
1591// decay
1592
1593template <class _Up, bool>
1594struct __decay {
1595    typedef _LIBCPP_NODEBUG_TYPE typename remove_cv<_Up>::type type;
1596};
1597
1598template <class _Up>
1599struct __decay<_Up, true> {
1600public:
1601    typedef _LIBCPP_NODEBUG_TYPE typename conditional
1602                     <
1603                         is_array<_Up>::value,
1604                         typename remove_extent<_Up>::type*,
1605                         typename conditional
1606                         <
1607                              is_function<_Up>::value,
1608                              typename add_pointer<_Up>::type,
1609                              typename remove_cv<_Up>::type
1610                         >::type
1611                     >::type type;
1612};
1613
1614template <class _Tp>
1615struct _LIBCPP_TEMPLATE_VIS decay
1616{
1617private:
1618    typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
1619public:
1620    typedef _LIBCPP_NODEBUG_TYPE typename __decay<_Up, __is_referenceable<_Up>::value>::type type;
1621};
1622
1623#if _LIBCPP_STD_VER > 11
1624template <class _Tp> using decay_t = typename decay<_Tp>::type;
1625#endif
1626
1627// is_abstract
1628
1629template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_abstract
1630    : public integral_constant<bool, __is_abstract(_Tp)> {};
1631
1632#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1633template <class _Tp>
1634_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_abstract_v
1635    = is_abstract<_Tp>::value;
1636#endif
1637
1638// is_final
1639
1640template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1641__libcpp_is_final : public integral_constant<bool, __is_final(_Tp)> {};
1642
1643#if _LIBCPP_STD_VER > 11
1644template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1645is_final : public integral_constant<bool, __is_final(_Tp)> {};
1646#endif
1647
1648#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1649template <class _Tp>
1650_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_final_v
1651    = is_final<_Tp>::value;
1652#endif
1653
1654// is_aggregate
1655#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_IS_AGGREGATE)
1656
1657template <class _Tp> struct _LIBCPP_TEMPLATE_VIS
1658is_aggregate : public integral_constant<bool, __is_aggregate(_Tp)> {};
1659
1660#if !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1661template <class _Tp>
1662_LIBCPP_INLINE_VAR constexpr bool is_aggregate_v
1663    = is_aggregate<_Tp>::value;
1664#endif
1665
1666#endif // _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_IS_AGGREGATE)
1667
1668// is_base_of
1669
1670template <class _Bp, class _Dp>
1671struct _LIBCPP_TEMPLATE_VIS is_base_of
1672    : public integral_constant<bool, __is_base_of(_Bp, _Dp)> {};
1673
1674#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1675template <class _Bp, class _Dp>
1676_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_base_of_v
1677    = is_base_of<_Bp, _Dp>::value;
1678#endif
1679
1680// __is_core_convertible
1681
1682// [conv.general]/3 says "E is convertible to T" whenever "T t=E;" is well-formed.
1683// We can't test for that, but we can test implicit convertibility by passing it
1684// to a function. Notice that __is_core_convertible<void,void> is false,
1685// and __is_core_convertible<immovable-type,immovable-type> is true in C++17 and later.
1686
1687template <class _Tp, class _Up, class = void>
1688struct __is_core_convertible : public false_type {};
1689
1690template <class _Tp, class _Up>
1691struct __is_core_convertible<_Tp, _Up, decltype(
1692    static_cast<void(*)(_Up)>(0) ( static_cast<_Tp(*)()>(0)() )
1693)> : public true_type {};
1694
1695// is_convertible
1696
1697#if __has_feature(is_convertible_to) && !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
1698
1699template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1700    : public integral_constant<bool, __is_convertible_to(_T1, _T2)> {};
1701
1702#else  // __has_feature(is_convertible_to)
1703
1704namespace __is_convertible_imp
1705{
1706template <class _Tp> void  __test_convert(_Tp);
1707
1708template <class _From, class _To, class = void>
1709struct __is_convertible_test : public false_type {};
1710
1711template <class _From, class _To>
1712struct __is_convertible_test<_From, _To,
1713    decltype(_VSTD::__is_convertible_imp::__test_convert<_To>(_VSTD::declval<_From>()))> : public true_type
1714{};
1715
1716template <class _Tp, bool _IsArray =    is_array<_Tp>::value,
1717                     bool _IsFunction = is_function<_Tp>::value,
1718                     bool _IsVoid =     is_void<_Tp>::value>
1719                     struct __is_array_function_or_void                          {enum {value = 0};};
1720template <class _Tp> struct __is_array_function_or_void<_Tp, true, false, false> {enum {value = 1};};
1721template <class _Tp> struct __is_array_function_or_void<_Tp, false, true, false> {enum {value = 2};};
1722template <class _Tp> struct __is_array_function_or_void<_Tp, false, false, true> {enum {value = 3};};
1723}
1724
1725template <class _Tp,
1726    unsigned = __is_convertible_imp::__is_array_function_or_void<typename remove_reference<_Tp>::type>::value>
1727struct __is_convertible_check
1728{
1729    static const size_t __v = 0;
1730};
1731
1732template <class _Tp>
1733struct __is_convertible_check<_Tp, 0>
1734{
1735    static const size_t __v = sizeof(_Tp);
1736};
1737
1738template <class _T1, class _T2,
1739    unsigned _T1_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T1>::value,
1740    unsigned _T2_is_array_function_or_void = __is_convertible_imp::__is_array_function_or_void<_T2>::value>
1741struct __is_convertible
1742    : public integral_constant<bool,
1743        __is_convertible_imp::__is_convertible_test<_T1, _T2>::value
1744    >
1745{};
1746
1747template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 1> : public false_type {};
1748template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 1> : public false_type {};
1749template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 1> : public false_type {};
1750template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 1> : public false_type {};
1751
1752template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 2> : public false_type {};
1753template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 2> : public false_type {};
1754template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 2> : public false_type {};
1755template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 2> : public false_type {};
1756
1757template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 3> : public false_type {};
1758template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 3> : public false_type {};
1759template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 3> : public false_type {};
1760template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 3> : public true_type {};
1761
1762template <class _T1, class _T2> struct _LIBCPP_TEMPLATE_VIS is_convertible
1763    : public __is_convertible<_T1, _T2>
1764{
1765    static const size_t __complete_check1 = __is_convertible_check<_T1>::__v;
1766    static const size_t __complete_check2 = __is_convertible_check<_T2>::__v;
1767};
1768
1769#endif  // __has_feature(is_convertible_to)
1770
1771#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1772template <class _From, class _To>
1773_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_convertible_v
1774    = is_convertible<_From, _To>::value;
1775#endif
1776
1777// is_nothrow_convertible
1778
1779#if _LIBCPP_STD_VER > 17
1780
1781template <typename _Tp>
1782static void __test_noexcept(_Tp) noexcept;
1783
1784template<typename _Fm, typename _To>
1785static bool_constant<noexcept(_VSTD::__test_noexcept<_To>(declval<_Fm>()))>
1786__is_nothrow_convertible_test();
1787
1788template <typename _Fm, typename _To>
1789struct __is_nothrow_convertible_helper: decltype(__is_nothrow_convertible_test<_Fm, _To>())
1790{ };
1791
1792template <typename _Fm, typename _To>
1793struct is_nothrow_convertible : _Or<
1794    _And<is_void<_To>, is_void<_Fm>>,
1795    _Lazy<_And, is_convertible<_Fm, _To>, __is_nothrow_convertible_helper<_Fm, _To>>
1796>::type { };
1797
1798template <typename _Fm, typename _To>
1799inline constexpr bool is_nothrow_convertible_v = is_nothrow_convertible<_Fm, _To>::value;
1800
1801#endif // _LIBCPP_STD_VER > 17
1802
1803// is_empty
1804
1805#if __has_feature(is_empty) || defined(_LIBCPP_COMPILER_GCC)
1806
1807template <class _Tp>
1808struct _LIBCPP_TEMPLATE_VIS is_empty
1809    : public integral_constant<bool, __is_empty(_Tp)> {};
1810
1811#else  // __has_feature(is_empty)
1812
1813template <class _Tp>
1814struct __is_empty1
1815    : public _Tp
1816{
1817    double __lx;
1818};
1819
1820struct __is_empty2
1821{
1822    double __lx;
1823};
1824
1825template <class _Tp, bool = is_class<_Tp>::value>
1826struct __libcpp_empty : public integral_constant<bool, sizeof(__is_empty1<_Tp>) == sizeof(__is_empty2)> {};
1827
1828template <class _Tp> struct __libcpp_empty<_Tp, false> : public false_type {};
1829
1830template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_empty : public __libcpp_empty<_Tp> {};
1831
1832#endif  // __has_feature(is_empty)
1833
1834#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1835template <class _Tp>
1836_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_empty_v
1837    = is_empty<_Tp>::value;
1838#endif
1839
1840// is_polymorphic
1841
1842#if __has_feature(is_polymorphic) || defined(_LIBCPP_COMPILER_MSVC)
1843
1844template <class _Tp>
1845struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1846    : public integral_constant<bool, __is_polymorphic(_Tp)> {};
1847
1848#else
1849
1850template<typename _Tp> char &__is_polymorphic_impl(
1851    typename enable_if<sizeof((_Tp*)dynamic_cast<const volatile void*>(declval<_Tp*>())) != 0,
1852                       int>::type);
1853template<typename _Tp> __two &__is_polymorphic_impl(...);
1854
1855template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_polymorphic
1856    : public integral_constant<bool, sizeof(__is_polymorphic_impl<_Tp>(0)) == 1> {};
1857
1858#endif // __has_feature(is_polymorphic)
1859
1860#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1861template <class _Tp>
1862_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_polymorphic_v
1863    = is_polymorphic<_Tp>::value;
1864#endif
1865
1866// has_virtual_destructor
1867
1868#if __has_feature(has_virtual_destructor) || defined(_LIBCPP_COMPILER_GCC)
1869
1870template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1871    : public integral_constant<bool, __has_virtual_destructor(_Tp)> {};
1872
1873#else
1874
1875template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_virtual_destructor
1876    : public false_type {};
1877
1878#endif
1879
1880#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1881template <class _Tp>
1882_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool has_virtual_destructor_v
1883    = has_virtual_destructor<_Tp>::value;
1884#endif
1885
1886// has_unique_object_representations
1887
1888#if _LIBCPP_STD_VER > 14 && defined(_LIBCPP_HAS_UNIQUE_OBJECT_REPRESENTATIONS)
1889
1890template <class _Tp> struct _LIBCPP_TEMPLATE_VIS has_unique_object_representations
1891    : public integral_constant<bool,
1892       __has_unique_object_representations(remove_cv_t<remove_all_extents_t<_Tp>>)> {};
1893
1894#if !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1895template <class _Tp>
1896_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool has_unique_object_representations_v
1897    = has_unique_object_representations<_Tp>::value;
1898#endif
1899
1900#endif
1901
1902// alignment_of
1903
1904template <class _Tp> struct _LIBCPP_TEMPLATE_VIS alignment_of
1905    : public integral_constant<size_t, _LIBCPP_ALIGNOF(_Tp)> {};
1906
1907#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
1908template <class _Tp>
1909_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR size_t alignment_of_v
1910    = alignment_of<_Tp>::value;
1911#endif
1912
1913// aligned_storage
1914
1915template <class _Hp, class _Tp>
1916struct __type_list
1917{
1918    typedef _Hp _Head;
1919    typedef _Tp _Tail;
1920};
1921
1922struct __nat
1923{
1924#ifndef _LIBCPP_CXX03_LANG
1925    __nat() = delete;
1926    __nat(const __nat&) = delete;
1927    __nat& operator=(const __nat&) = delete;
1928    ~__nat() = delete;
1929#endif
1930};
1931
1932template <class _Tp>
1933struct __align_type
1934{
1935    static const size_t value = _LIBCPP_PREFERRED_ALIGNOF(_Tp);
1936    typedef _Tp type;
1937};
1938
1939struct __struct_double {long double __lx;};
1940struct __struct_double4 {double __lx[4];};
1941
1942typedef
1943    __type_list<__align_type<unsigned char>,
1944    __type_list<__align_type<unsigned short>,
1945    __type_list<__align_type<unsigned int>,
1946    __type_list<__align_type<unsigned long>,
1947    __type_list<__align_type<unsigned long long>,
1948    __type_list<__align_type<double>,
1949    __type_list<__align_type<long double>,
1950    __type_list<__align_type<__struct_double>,
1951    __type_list<__align_type<__struct_double4>,
1952    __type_list<__align_type<int*>,
1953    __nat
1954    > > > > > > > > > > __all_types;
1955
1956template <size_t _Align>
1957struct _ALIGNAS(_Align) __fallback_overaligned {};
1958
1959template <class _TL, size_t _Align> struct __find_pod;
1960
1961template <class _Hp, size_t _Align>
1962struct __find_pod<__type_list<_Hp, __nat>, _Align>
1963{
1964    typedef typename conditional<
1965                             _Align == _Hp::value,
1966                             typename _Hp::type,
1967                             __fallback_overaligned<_Align>
1968                         >::type type;
1969};
1970
1971template <class _Hp, class _Tp, size_t _Align>
1972struct __find_pod<__type_list<_Hp, _Tp>, _Align>
1973{
1974    typedef typename conditional<
1975                             _Align == _Hp::value,
1976                             typename _Hp::type,
1977                             typename __find_pod<_Tp, _Align>::type
1978                         >::type type;
1979};
1980
1981template <class _TL, size_t _Len> struct __find_max_align;
1982
1983template <class _Hp, size_t _Len>
1984struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
1985
1986template <size_t _Len, size_t _A1, size_t _A2>
1987struct __select_align
1988{
1989private:
1990    static const size_t __min = _A2 < _A1 ? _A2 : _A1;
1991    static const size_t __max = _A1 < _A2 ? _A2 : _A1;
1992public:
1993    static const size_t value = _Len < __max ? __min : __max;
1994};
1995
1996template <class _Hp, class _Tp, size_t _Len>
1997struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
1998    : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
1999
2000template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
2001struct _LIBCPP_TEMPLATE_VIS aligned_storage
2002{
2003    typedef typename __find_pod<__all_types, _Align>::type _Aligner;
2004    union type
2005    {
2006        _Aligner __align;
2007        unsigned char __data[(_Len + _Align - 1)/_Align * _Align];
2008    };
2009};
2010
2011#if _LIBCPP_STD_VER > 11
2012template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
2013    using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
2014#endif
2015
2016#define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \
2017template <size_t _Len>\
2018struct _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n>\
2019{\
2020    struct _ALIGNAS(n) type\
2021    {\
2022        unsigned char __lx[(_Len + n - 1)/n * n];\
2023    };\
2024}
2025
2026_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
2027_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
2028_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
2029_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
2030_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
2031_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
2032_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
2033_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
2034_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
2035_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
2036_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
2037_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
2038_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
2039_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
2040// PE/COFF does not support alignment beyond 8192 (=0x2000)
2041#if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
2042_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
2043#endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF)
2044
2045#undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION
2046
2047
2048// aligned_union
2049
2050template <size_t _I0, size_t ..._In>
2051struct __static_max;
2052
2053template <size_t _I0>
2054struct __static_max<_I0>
2055{
2056    static const size_t value = _I0;
2057};
2058
2059template <size_t _I0, size_t _I1, size_t ..._In>
2060struct __static_max<_I0, _I1, _In...>
2061{
2062    static const size_t value = _I0 >= _I1 ? __static_max<_I0, _In...>::value :
2063                                             __static_max<_I1, _In...>::value;
2064};
2065
2066template <size_t _Len, class _Type0, class ..._Types>
2067struct aligned_union
2068{
2069    static const size_t alignment_value = __static_max<_LIBCPP_PREFERRED_ALIGNOF(_Type0),
2070                                                       _LIBCPP_PREFERRED_ALIGNOF(_Types)...>::value;
2071    static const size_t __len = __static_max<_Len, sizeof(_Type0),
2072                                             sizeof(_Types)...>::value;
2073    typedef typename aligned_storage<__len, alignment_value>::type type;
2074};
2075
2076#if _LIBCPP_STD_VER > 11
2077template <size_t _Len, class ..._Types> using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
2078#endif
2079
2080template <class _Tp>
2081struct __numeric_type
2082{
2083   static void __test(...);
2084   static float __test(float);
2085   static double __test(char);
2086   static double __test(int);
2087   static double __test(unsigned);
2088   static double __test(long);
2089   static double __test(unsigned long);
2090   static double __test(long long);
2091   static double __test(unsigned long long);
2092   static double __test(double);
2093   static long double __test(long double);
2094
2095   typedef decltype(__test(declval<_Tp>())) type;
2096   static const bool value = _IsNotSame<type, void>::value;
2097};
2098
2099template <>
2100struct __numeric_type<void>
2101{
2102   static const bool value = true;
2103};
2104
2105// __promote
2106
2107template <class _A1, class _A2 = void, class _A3 = void,
2108          bool = __numeric_type<_A1>::value &&
2109                 __numeric_type<_A2>::value &&
2110                 __numeric_type<_A3>::value>
2111class __promote_imp
2112{
2113public:
2114    static const bool value = false;
2115};
2116
2117template <class _A1, class _A2, class _A3>
2118class __promote_imp<_A1, _A2, _A3, true>
2119{
2120private:
2121    typedef typename __promote_imp<_A1>::type __type1;
2122    typedef typename __promote_imp<_A2>::type __type2;
2123    typedef typename __promote_imp<_A3>::type __type3;
2124public:
2125    typedef decltype(__type1() + __type2() + __type3()) type;
2126    static const bool value = true;
2127};
2128
2129template <class _A1, class _A2>
2130class __promote_imp<_A1, _A2, void, true>
2131{
2132private:
2133    typedef typename __promote_imp<_A1>::type __type1;
2134    typedef typename __promote_imp<_A2>::type __type2;
2135public:
2136    typedef decltype(__type1() + __type2()) type;
2137    static const bool value = true;
2138};
2139
2140template <class _A1>
2141class __promote_imp<_A1, void, void, true>
2142{
2143public:
2144    typedef typename __numeric_type<_A1>::type type;
2145    static const bool value = true;
2146};
2147
2148template <class _A1, class _A2 = void, class _A3 = void>
2149class __promote : public __promote_imp<_A1, _A2, _A3> {};
2150
2151// make_signed / make_unsigned
2152
2153typedef
2154    __type_list<signed char,
2155    __type_list<signed short,
2156    __type_list<signed int,
2157    __type_list<signed long,
2158    __type_list<signed long long,
2159#ifndef _LIBCPP_HAS_NO_INT128
2160    __type_list<__int128_t,
2161#endif
2162    __nat
2163#ifndef _LIBCPP_HAS_NO_INT128
2164    >
2165#endif
2166    > > > > > __signed_types;
2167
2168typedef
2169    __type_list<unsigned char,
2170    __type_list<unsigned short,
2171    __type_list<unsigned int,
2172    __type_list<unsigned long,
2173    __type_list<unsigned long long,
2174#ifndef _LIBCPP_HAS_NO_INT128
2175    __type_list<__uint128_t,
2176#endif
2177    __nat
2178#ifndef _LIBCPP_HAS_NO_INT128
2179    >
2180#endif
2181    > > > > > __unsigned_types;
2182
2183template <class _TypeList, size_t _Size, bool = _Size <= sizeof(typename _TypeList::_Head)> struct __find_first;
2184
2185template <class _Hp, class _Tp, size_t _Size>
2186struct __find_first<__type_list<_Hp, _Tp>, _Size, true>
2187{
2188    typedef _LIBCPP_NODEBUG_TYPE _Hp type;
2189};
2190
2191template <class _Hp, class _Tp, size_t _Size>
2192struct __find_first<__type_list<_Hp, _Tp>, _Size, false>
2193{
2194    typedef _LIBCPP_NODEBUG_TYPE typename __find_first<_Tp, _Size>::type type;
2195};
2196
2197template <class _Tp, class _Up, bool = is_const<typename remove_reference<_Tp>::type>::value,
2198                             bool = is_volatile<typename remove_reference<_Tp>::type>::value>
2199struct __apply_cv
2200{
2201    typedef _LIBCPP_NODEBUG_TYPE _Up type;
2202};
2203
2204template <class _Tp, class _Up>
2205struct __apply_cv<_Tp, _Up, true, false>
2206{
2207    typedef _LIBCPP_NODEBUG_TYPE const _Up type;
2208};
2209
2210template <class _Tp, class _Up>
2211struct __apply_cv<_Tp, _Up, false, true>
2212{
2213    typedef volatile _Up type;
2214};
2215
2216template <class _Tp, class _Up>
2217struct __apply_cv<_Tp, _Up, true, true>
2218{
2219    typedef const volatile _Up type;
2220};
2221
2222template <class _Tp, class _Up>
2223struct __apply_cv<_Tp&, _Up, false, false>
2224{
2225    typedef _Up& type;
2226};
2227
2228template <class _Tp, class _Up>
2229struct __apply_cv<_Tp&, _Up, true, false>
2230{
2231    typedef const _Up& type;
2232};
2233
2234template <class _Tp, class _Up>
2235struct __apply_cv<_Tp&, _Up, false, true>
2236{
2237    typedef volatile _Up& type;
2238};
2239
2240template <class _Tp, class _Up>
2241struct __apply_cv<_Tp&, _Up, true, true>
2242{
2243    typedef const volatile _Up& type;
2244};
2245
2246template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
2247struct __make_signed {};
2248
2249template <class _Tp>
2250struct __make_signed<_Tp, true>
2251{
2252    typedef typename __find_first<__signed_types, sizeof(_Tp)>::type type;
2253};
2254
2255template <> struct __make_signed<bool,               true> {};
2256template <> struct __make_signed<  signed short,     true> {typedef short     type;};
2257template <> struct __make_signed<unsigned short,     true> {typedef short     type;};
2258template <> struct __make_signed<  signed int,       true> {typedef int       type;};
2259template <> struct __make_signed<unsigned int,       true> {typedef int       type;};
2260template <> struct __make_signed<  signed long,      true> {typedef long      type;};
2261template <> struct __make_signed<unsigned long,      true> {typedef long      type;};
2262template <> struct __make_signed<  signed long long, true> {typedef long long type;};
2263template <> struct __make_signed<unsigned long long, true> {typedef long long type;};
2264#ifndef _LIBCPP_HAS_NO_INT128
2265template <> struct __make_signed<__int128_t,         true> {typedef __int128_t type;};
2266template <> struct __make_signed<__uint128_t,        true> {typedef __int128_t type;};
2267#endif
2268
2269template <class _Tp>
2270struct _LIBCPP_TEMPLATE_VIS make_signed
2271{
2272    typedef typename __apply_cv<_Tp, typename __make_signed<typename remove_cv<_Tp>::type>::type>::type type;
2273};
2274
2275#if _LIBCPP_STD_VER > 11
2276template <class _Tp> using make_signed_t = typename make_signed<_Tp>::type;
2277#endif
2278
2279template <class _Tp, bool = is_integral<_Tp>::value || is_enum<_Tp>::value>
2280struct __make_unsigned {};
2281
2282template <class _Tp>
2283struct __make_unsigned<_Tp, true>
2284{
2285    typedef typename __find_first<__unsigned_types, sizeof(_Tp)>::type type;
2286};
2287
2288template <> struct __make_unsigned<bool,               true> {};
2289template <> struct __make_unsigned<  signed short,     true> {typedef unsigned short     type;};
2290template <> struct __make_unsigned<unsigned short,     true> {typedef unsigned short     type;};
2291template <> struct __make_unsigned<  signed int,       true> {typedef unsigned int       type;};
2292template <> struct __make_unsigned<unsigned int,       true> {typedef unsigned int       type;};
2293template <> struct __make_unsigned<  signed long,      true> {typedef unsigned long      type;};
2294template <> struct __make_unsigned<unsigned long,      true> {typedef unsigned long      type;};
2295template <> struct __make_unsigned<  signed long long, true> {typedef unsigned long long type;};
2296template <> struct __make_unsigned<unsigned long long, true> {typedef unsigned long long type;};
2297#ifndef _LIBCPP_HAS_NO_INT128
2298template <> struct __make_unsigned<__int128_t,         true> {typedef __uint128_t        type;};
2299template <> struct __make_unsigned<__uint128_t,        true> {typedef __uint128_t        type;};
2300#endif
2301
2302template <class _Tp>
2303struct _LIBCPP_TEMPLATE_VIS make_unsigned
2304{
2305    typedef typename __apply_cv<_Tp, typename __make_unsigned<typename remove_cv<_Tp>::type>::type>::type type;
2306};
2307
2308#if _LIBCPP_STD_VER > 11
2309template <class _Tp> using make_unsigned_t = typename make_unsigned<_Tp>::type;
2310#endif
2311
2312#if _LIBCPP_STD_VER > 14
2313template <class...> using void_t = void;
2314#endif
2315
2316#if _LIBCPP_STD_VER > 17
2317// Let COND_RES(X, Y) be:
2318template <class _Tp, class _Up>
2319using __cond_type = decltype(false ? _VSTD::declval<_Tp>() : _VSTD::declval<_Up>());
2320
2321template <class _Tp, class _Up, class = void>
2322struct __common_type3 {};
2323
2324// sub-bullet 4 - "if COND_RES(CREF(D1), CREF(D2)) denotes a type..."
2325template <class _Tp, class _Up>
2326struct __common_type3<_Tp, _Up, void_t<__cond_type<const _Tp&, const _Up&>>>
2327{
2328    using type = remove_cvref_t<__cond_type<const _Tp&, const _Up&>>;
2329};
2330
2331template <class _Tp, class _Up, class = void>
2332struct __common_type2_imp : __common_type3<_Tp, _Up> {};
2333#else
2334template <class _Tp, class _Up, class = void>
2335struct __common_type2_imp {};
2336#endif
2337
2338// sub-bullet 3 - "if decay_t<decltype(false ? declval<D1>() : declval<D2>())> ..."
2339template <class _Tp, class _Up>
2340struct __common_type2_imp<_Tp, _Up,
2341                          typename __void_t<decltype(
2342                                            true ? _VSTD::declval<_Tp>() : _VSTD::declval<_Up>()
2343                                            )>::type>
2344{
2345  typedef _LIBCPP_NODEBUG_TYPE typename decay<decltype(
2346                         true ? _VSTD::declval<_Tp>() : _VSTD::declval<_Up>()
2347                         )>::type type;
2348};
2349
2350template <class, class = void>
2351struct __common_type_impl {};
2352
2353// Clang provides variadic templates in C++03 as an extension.
2354#if !defined(_LIBCPP_CXX03_LANG) || defined(__clang__)
2355# define _LIBCPP_OPTIONAL_PACK(...) , __VA_ARGS__
2356template <class... Tp>
2357struct __common_types;
2358template <class... _Tp>
2359struct _LIBCPP_TEMPLATE_VIS common_type;
2360#else
2361# define _LIBCPP_OPTIONAL_PACK(...)
2362struct __no_arg;
2363template <class _Tp, class _Up, class = __no_arg>
2364struct __common_types;
2365template <class _Tp = __no_arg, class _Up = __no_arg, class _Vp = __no_arg,
2366          class _Unused = __no_arg>
2367struct common_type {
2368  static_assert(sizeof(_Unused) == 0,
2369                "common_type accepts at most 3 arguments in C++03");
2370};
2371#endif // _LIBCPP_CXX03_LANG
2372
2373template <class _Tp, class _Up>
2374struct __common_type_impl<
2375    __common_types<_Tp, _Up>,
2376    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2377{
2378  typedef typename common_type<_Tp, _Up>::type type;
2379};
2380
2381template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2382struct __common_type_impl<
2383    __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>,
2384    typename __void_t<typename common_type<_Tp, _Up>::type>::type>
2385    : __common_type_impl<__common_types<typename common_type<_Tp, _Up>::type,
2386                                        _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {
2387};
2388
2389// bullet 1 - sizeof...(Tp) == 0
2390
2391template <>
2392struct _LIBCPP_TEMPLATE_VIS common_type<> {};
2393
2394// bullet 2 - sizeof...(Tp) == 1
2395
2396template <class _Tp>
2397struct _LIBCPP_TEMPLATE_VIS common_type<_Tp>
2398    : public common_type<_Tp, _Tp> {};
2399
2400// bullet 3 - sizeof...(Tp) == 2
2401
2402// sub-bullet 1 - "If is_same_v<T1, D1> is false or ..."
2403template <class _Tp, class _Up>
2404struct _LIBCPP_TEMPLATE_VIS common_type<_Tp, _Up>
2405    : conditional<
2406        _IsSame<_Tp, typename decay<_Tp>::type>::value && _IsSame<_Up, typename decay<_Up>::type>::value,
2407        __common_type2_imp<_Tp, _Up>,
2408        common_type<typename decay<_Tp>::type, typename decay<_Up>::type>
2409    >::type
2410{};
2411
2412// bullet 4 - sizeof...(Tp) > 2
2413
2414template <class _Tp, class _Up, class _Vp _LIBCPP_OPTIONAL_PACK(class... _Rest)>
2415struct _LIBCPP_TEMPLATE_VIS
2416    common_type<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)>
2417    : __common_type_impl<
2418          __common_types<_Tp, _Up, _Vp _LIBCPP_OPTIONAL_PACK(_Rest...)> > {};
2419
2420#undef _LIBCPP_OPTIONAL_PACK
2421
2422#if _LIBCPP_STD_VER > 11
2423template <class ..._Tp> using common_type_t = typename common_type<_Tp...>::type;
2424#endif
2425
2426#if _LIBCPP_STD_VER > 11
2427// Let COPYCV(FROM, TO) be an alias for type TO with the addition of FROM’s
2428// top-level cv-qualifiers.
2429template <class _From, class _To>
2430struct __copy_cv
2431{
2432    using type = _To;
2433};
2434
2435template <class _From, class _To>
2436struct __copy_cv<const _From, _To>
2437{
2438    using type = add_const_t<_To>;
2439};
2440
2441template <class _From, class _To>
2442struct __copy_cv<volatile _From, _To>
2443{
2444    using type = add_volatile_t<_To>;
2445};
2446
2447template <class _From, class _To>
2448struct __copy_cv<const volatile _From, _To>
2449{
2450    using type = add_cv_t<_To>;
2451};
2452
2453template <class _From, class _To>
2454using __copy_cv_t = typename __copy_cv<_From, _To>::type;
2455
2456template <class _From, class _To>
2457struct __copy_cvref
2458{
2459    using type = __copy_cv_t<_From, _To>;
2460};
2461
2462template <class _From, class _To>
2463struct __copy_cvref<_From&, _To>
2464{
2465    using type = add_lvalue_reference_t<__copy_cv_t<_From, _To>>;
2466};
2467
2468template <class _From, class _To>
2469struct __copy_cvref<_From&&, _To>
2470{
2471    using type = add_rvalue_reference_t<__copy_cv_t<_From, _To>>;
2472};
2473
2474template <class _From, class _To>
2475using __copy_cvref_t = typename __copy_cvref<_From, _To>::type;
2476
2477#endif // _LIBCPP_STD_VER > 11
2478
2479// common_reference
2480#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
2481// Let COND_RES(X, Y) be:
2482template <class _Xp, class _Yp>
2483using __cond_res =
2484    decltype(false ? _VSTD::declval<_Xp(&)()>()() : _VSTD::declval<_Yp(&)()>()());
2485
2486// Let `XREF(A)` denote a unary alias template `T` such that `T<U>` denotes the same type as `U`
2487// with the addition of `A`'s cv and reference qualifiers, for a non-reference cv-unqualified type
2488// `U`.
2489// [Note: `XREF(A)` is `__xref<A>::template __apply`]
2490template <class _Tp>
2491struct __xref {
2492  template<class _Up>
2493  using __apply = __copy_cvref_t<_Tp, _Up>;
2494};
2495
2496// Given types `A` and `B`, let `X` be `remove_­reference_­t<A>`, let `Y` be `remove_­reference_­t<B>`,
2497// and let `COMMON-​REF(A, B)` be:
2498template<class _Ap, class _Bp, class _Xp = remove_reference_t<_Ap>, class _Yp = remove_reference_t<_Bp>>
2499struct __common_ref;
2500
2501template<class _Xp, class _Yp>
2502using __common_ref_t = typename __common_ref<_Xp, _Yp>::__type;
2503
2504template<class _Xp, class _Yp>
2505using __cv_cond_res = __cond_res<__copy_cv_t<_Xp, _Yp>&, __copy_cv_t<_Yp, _Xp>&>;
2506
2507
2508//    If `A` and `B` are both lvalue reference types, `COMMON-REF(A, B)` is
2509//    `COND-RES(COPYCV(X, Y) &, COPYCV(​Y, X) &)` if that type exists and is a reference type.
2510template<class _Ap, class _Bp, class _Xp, class _Yp>
2511requires requires { typename __cv_cond_res<_Xp, _Yp>; } && is_reference_v<__cv_cond_res<_Xp, _Yp>>
2512struct __common_ref<_Ap&, _Bp&, _Xp, _Yp>
2513{
2514    using __type = __cv_cond_res<_Xp, _Yp>;
2515};
2516
2517//    Otherwise, let `C` be `remove_­reference_­t<COMMON-REF(X&, Y&)>&&`....
2518template <class _Xp, class _Yp>
2519using __common_ref_C = remove_reference_t<__common_ref_t<_Xp&, _Yp&>>&&;
2520
2521
2522//    .... If `A` and `B` are both rvalue reference types, `C` is well-formed, and
2523//    `is_­convertible_­v<A, C> && is_­convertible_­v<B, C>` is `true`, then `COMMON-REF(A, B)` is `C`.
2524template<class _Ap, class _Bp, class _Xp, class _Yp>
2525requires
2526  requires { typename __common_ref_C<_Xp, _Yp>; } &&
2527  is_convertible_v<_Ap&&, __common_ref_C<_Xp, _Yp>> &&
2528  is_convertible_v<_Bp&&, __common_ref_C<_Xp, _Yp>>
2529struct __common_ref<_Ap&&, _Bp&&, _Xp, _Yp>
2530{
2531    using __type = __common_ref_C<_Xp, _Yp>;
2532};
2533
2534//    Otherwise, let `D` be `COMMON-REF(const X&, Y&)`....
2535template <class _Tp, class _Up>
2536using __common_ref_D = __common_ref_t<const _Tp&, _Up&>;
2537
2538//    ... If `A` is an rvalue reference and `B` is an lvalue reference and `D` is well-formed and
2539//    `is_­convertible_­v<A, D>` is `true`, then `COMMON-REF(A, B)` is `D`.
2540template<class _Ap, class _Bp, class _Xp, class _Yp>
2541requires requires { typename __common_ref_D<_Xp, _Yp>; } &&
2542         is_convertible_v<_Ap&&, __common_ref_D<_Xp, _Yp>>
2543struct __common_ref<_Ap&&, _Bp&, _Xp, _Yp>
2544{
2545    using __type = __common_ref_D<_Xp, _Yp>;
2546};
2547
2548//    Otherwise, if `A` is an lvalue reference and `B` is an rvalue reference, then
2549//    `COMMON-REF(A, B)` is `COMMON-REF(B, A)`.
2550template<class _Ap, class _Bp, class _Xp, class _Yp>
2551struct __common_ref<_Ap&, _Bp&&, _Xp, _Yp> : __common_ref<_Bp&&, _Ap&> {};
2552
2553//    Otherwise, `COMMON-REF(A, B)` is ill-formed.
2554template<class _Ap, class _Bp, class _Xp, class _Yp>
2555struct __common_ref {};
2556
2557// Note C: For the common_reference trait applied to a parameter pack [...]
2558
2559template <class...>
2560struct common_reference;
2561
2562template <class... _Types>
2563using common_reference_t = typename common_reference<_Types...>::type;
2564
2565// bullet 1 - sizeof...(T) == 0
2566template<>
2567struct common_reference<> {};
2568
2569// bullet 2 - sizeof...(T) == 1
2570template <class _Tp>
2571struct common_reference<_Tp>
2572{
2573    using type = _Tp;
2574};
2575
2576// bullet 3 - sizeof...(T) == 2
2577template <class _Tp, class _Up> struct __common_reference_sub_bullet3;
2578template <class _Tp, class _Up> struct __common_reference_sub_bullet2 : __common_reference_sub_bullet3<_Tp, _Up> {};
2579template <class _Tp, class _Up> struct __common_reference_sub_bullet1 : __common_reference_sub_bullet2<_Tp, _Up> {};
2580
2581// sub-bullet 1 - If `T1` and `T2` are reference types and `COMMON-REF(T1, T2)` is well-formed, then
2582// the member typedef type denotes that type.
2583template <class _Tp, class _Up> struct common_reference<_Tp, _Up> : __common_reference_sub_bullet1<_Tp, _Up> {};
2584
2585template <class _Tp, class _Up>
2586requires is_reference_v<_Tp> && is_reference_v<_Up> && requires { typename __common_ref_t<_Tp, _Up>; }
2587struct __common_reference_sub_bullet1<_Tp, _Up>
2588{
2589    using type = __common_ref_t<_Tp, _Up>;
2590};
2591
2592// sub-bullet 2 - Otherwise, if `basic_­common_­reference<remove_­cvref_­t<T1>, remove_­cvref_­t<T2>, ​XREF(​T1), XREF(T2)>​::​type`
2593// is well-formed, then the member typedef type denotes that type.
2594template <class, class, template <class> class, template <class> class> struct basic_common_reference {};
2595
2596template <class _Tp, class _Up>
2597using __basic_common_reference_t = typename basic_common_reference<
2598    remove_cvref_t<_Tp>, remove_cvref_t<_Up>,
2599    __xref<_Tp>::template __apply, __xref<_Up>::template __apply>::type;
2600
2601template <class _Tp, class _Up>
2602requires requires { typename __basic_common_reference_t<_Tp, _Up>; }
2603struct __common_reference_sub_bullet2<_Tp, _Up>
2604{
2605    using type = __basic_common_reference_t<_Tp, _Up>;
2606};
2607
2608// sub-bullet 3 - Otherwise, if `COND-RES(T1, T2)` is well-formed, then the member typedef type
2609// denotes that type.
2610template <class _Tp, class _Up>
2611requires requires { typename __cond_res<_Tp, _Up>; }
2612struct __common_reference_sub_bullet3<_Tp, _Up>
2613{
2614    using type = __cond_res<_Tp, _Up>;
2615};
2616
2617
2618// sub-bullet 4 & 5 - Otherwise, if `common_­type_­t<T1, T2>` is well-formed, then the member typedef
2619//                    type denotes that type.
2620//                  - Otherwise, there shall be no member type.
2621template <class _Tp, class _Up> struct __common_reference_sub_bullet3 : common_type<_Tp, _Up> {};
2622
2623// bullet 4 - If there is such a type `C`, the member typedef type shall denote the same type, if
2624//            any, as `common_­reference_­t<C, Rest...>`.
2625template <class _Tp, class _Up, class _Vp, class... _Rest>
2626requires requires { typename common_reference_t<_Tp, _Up>; }
2627struct common_reference<_Tp, _Up, _Vp, _Rest...>
2628    : common_reference<common_reference_t<_Tp, _Up>, _Vp, _Rest...>
2629{};
2630
2631// bullet 5 - Otherwise, there shall be no member type.
2632template <class...> struct common_reference {};
2633
2634#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
2635
2636// is_assignable
2637
2638template<typename, typename _Tp> struct __select_2nd { typedef _LIBCPP_NODEBUG_TYPE _Tp type; };
2639
2640#if __has_keyword(__is_assignable)
2641
2642template<class _Tp, class _Up>
2643struct _LIBCPP_TEMPLATE_VIS is_assignable : _BoolConstant<__is_assignable(_Tp, _Up)> { };
2644
2645#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2646template <class _Tp, class _Arg>
2647_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_assignable_v = __is_assignable(_Tp, _Arg);
2648#endif
2649
2650#else // __has_keyword(__is_assignable)
2651
2652template <class _Tp, class _Arg>
2653typename __select_2nd<decltype((_VSTD::declval<_Tp>() = _VSTD::declval<_Arg>())), true_type>::type
2654__is_assignable_test(int);
2655
2656template <class, class>
2657false_type __is_assignable_test(...);
2658
2659
2660template <class _Tp, class _Arg, bool = is_void<_Tp>::value || is_void<_Arg>::value>
2661struct __is_assignable_imp
2662    : public decltype((_VSTD::__is_assignable_test<_Tp, _Arg>(0))) {};
2663
2664template <class _Tp, class _Arg>
2665struct __is_assignable_imp<_Tp, _Arg, true>
2666    : public false_type
2667{
2668};
2669
2670template <class _Tp, class _Arg>
2671struct is_assignable
2672    : public __is_assignable_imp<_Tp, _Arg> {};
2673
2674#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2675template <class _Tp, class _Arg>
2676_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_assignable_v
2677    = is_assignable<_Tp, _Arg>::value;
2678#endif
2679
2680#endif  // __has_keyword(__is_assignable)
2681
2682// is_copy_assignable
2683
2684template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_copy_assignable
2685    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2686                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
2687
2688#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2689template <class _Tp>
2690_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_copy_assignable_v
2691    = is_copy_assignable<_Tp>::value;
2692#endif
2693
2694// is_move_assignable
2695
2696template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_move_assignable
2697    : public is_assignable<typename add_lvalue_reference<_Tp>::type,
2698                           typename add_rvalue_reference<_Tp>::type> {};
2699
2700#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2701template <class _Tp>
2702_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_move_assignable_v
2703    = is_move_assignable<_Tp>::value;
2704#endif
2705
2706// is_destructible
2707
2708#if __has_keyword(__is_destructible)
2709
2710template<class _Tp>
2711struct _LIBCPP_TEMPLATE_VIS is_destructible : _BoolConstant<__is_destructible(_Tp)> { };
2712
2713#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2714template <class _Tp>
2715_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_destructible_v = __is_destructible(_Tp);
2716#endif
2717
2718#else // __has_keyword(__is_destructible)
2719
2720//  if it's a reference, return true
2721//  if it's a function, return false
2722//  if it's   void,     return false
2723//  if it's an array of unknown bound, return false
2724//  Otherwise, return "declval<_Up&>().~_Up()" is well-formed
2725//    where _Up is remove_all_extents<_Tp>::type
2726
2727template <class>
2728struct __is_destructible_apply { typedef int type; };
2729
2730template <typename _Tp>
2731struct __is_destructor_wellformed {
2732    template <typename _Tp1>
2733    static char  __test (
2734        typename __is_destructible_apply<decltype(_VSTD::declval<_Tp1&>().~_Tp1())>::type
2735    );
2736
2737    template <typename _Tp1>
2738    static __two __test (...);
2739
2740    static const bool value = sizeof(__test<_Tp>(12)) == sizeof(char);
2741};
2742
2743template <class _Tp, bool>
2744struct __destructible_imp;
2745
2746template <class _Tp>
2747struct __destructible_imp<_Tp, false>
2748   : public _VSTD::integral_constant<bool,
2749        __is_destructor_wellformed<typename _VSTD::remove_all_extents<_Tp>::type>::value> {};
2750
2751template <class _Tp>
2752struct __destructible_imp<_Tp, true>
2753    : public _VSTD::true_type {};
2754
2755template <class _Tp, bool>
2756struct __destructible_false;
2757
2758template <class _Tp>
2759struct __destructible_false<_Tp, false> : public __destructible_imp<_Tp, _VSTD::is_reference<_Tp>::value> {};
2760
2761template <class _Tp>
2762struct __destructible_false<_Tp, true> : public _VSTD::false_type {};
2763
2764template <class _Tp>
2765struct is_destructible
2766    : public __destructible_false<_Tp, _VSTD::is_function<_Tp>::value> {};
2767
2768template <class _Tp>
2769struct is_destructible<_Tp[]>
2770    : public _VSTD::false_type {};
2771
2772template <>
2773struct is_destructible<void>
2774    : public _VSTD::false_type {};
2775
2776#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
2777template <class _Tp>
2778_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_destructible_v
2779    = is_destructible<_Tp>::value;
2780#endif
2781
2782#endif // __has_keyword(__is_destructible)
2783
2784// move
2785
2786template <class _Tp>
2787_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2788typename remove_reference<_Tp>::type&&
2789move(_Tp&& __t) _NOEXCEPT
2790{
2791    typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type _Up;
2792    return static_cast<_Up&&>(__t);
2793}
2794
2795template <class _Tp>
2796_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2797_Tp&&
2798forward(typename remove_reference<_Tp>::type& __t) _NOEXCEPT
2799{
2800    return static_cast<_Tp&&>(__t);
2801}
2802
2803template <class _Tp>
2804_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2805_Tp&&
2806forward(typename remove_reference<_Tp>::type&& __t) _NOEXCEPT
2807{
2808    static_assert(!is_lvalue_reference<_Tp>::value,
2809                  "cannot forward an rvalue as an lvalue");
2810    return static_cast<_Tp&&>(__t);
2811}
2812
2813template <class _Tp>
2814inline _LIBCPP_INLINE_VISIBILITY
2815typename decay<_Tp>::type
2816__decay_copy(_Tp&& __t)
2817{
2818    return _VSTD::forward<_Tp>(__t);
2819}
2820
2821template <class _MP, bool _IsMemberFunctionPtr, bool _IsMemberObjectPtr>
2822struct __member_pointer_traits_imp
2823{
2824};
2825
2826template <class _Rp, class _Class, class ..._Param>
2827struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...), true, false>
2828{
2829    typedef _Class _ClassType;
2830    typedef _Rp _ReturnType;
2831    typedef _Rp (_FnType) (_Param...);
2832};
2833
2834template <class _Rp, class _Class, class ..._Param>
2835struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...), true, false>
2836{
2837    typedef _Class _ClassType;
2838    typedef _Rp _ReturnType;
2839    typedef _Rp (_FnType) (_Param..., ...);
2840};
2841
2842template <class _Rp, class _Class, class ..._Param>
2843struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const, true, false>
2844{
2845    typedef _Class const _ClassType;
2846    typedef _Rp _ReturnType;
2847    typedef _Rp (_FnType) (_Param...);
2848};
2849
2850template <class _Rp, class _Class, class ..._Param>
2851struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const, true, false>
2852{
2853    typedef _Class const _ClassType;
2854    typedef _Rp _ReturnType;
2855    typedef _Rp (_FnType) (_Param..., ...);
2856};
2857
2858template <class _Rp, class _Class, class ..._Param>
2859struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile, true, false>
2860{
2861    typedef _Class volatile _ClassType;
2862    typedef _Rp _ReturnType;
2863    typedef _Rp (_FnType) (_Param...);
2864};
2865
2866template <class _Rp, class _Class, class ..._Param>
2867struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile, true, false>
2868{
2869    typedef _Class volatile _ClassType;
2870    typedef _Rp _ReturnType;
2871    typedef _Rp (_FnType) (_Param..., ...);
2872};
2873
2874template <class _Rp, class _Class, class ..._Param>
2875struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile, true, false>
2876{
2877    typedef _Class const volatile _ClassType;
2878    typedef _Rp _ReturnType;
2879    typedef _Rp (_FnType) (_Param...);
2880};
2881
2882template <class _Rp, class _Class, class ..._Param>
2883struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile, true, false>
2884{
2885    typedef _Class const volatile _ClassType;
2886    typedef _Rp _ReturnType;
2887    typedef _Rp (_FnType) (_Param..., ...);
2888};
2889
2890#if __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
2891
2892template <class _Rp, class _Class, class ..._Param>
2893struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &, true, false>
2894{
2895    typedef _Class& _ClassType;
2896    typedef _Rp _ReturnType;
2897    typedef _Rp (_FnType) (_Param...);
2898};
2899
2900template <class _Rp, class _Class, class ..._Param>
2901struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &, true, false>
2902{
2903    typedef _Class& _ClassType;
2904    typedef _Rp _ReturnType;
2905    typedef _Rp (_FnType) (_Param..., ...);
2906};
2907
2908template <class _Rp, class _Class, class ..._Param>
2909struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&, true, false>
2910{
2911    typedef _Class const& _ClassType;
2912    typedef _Rp _ReturnType;
2913    typedef _Rp (_FnType) (_Param...);
2914};
2915
2916template <class _Rp, class _Class, class ..._Param>
2917struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&, true, false>
2918{
2919    typedef _Class const& _ClassType;
2920    typedef _Rp _ReturnType;
2921    typedef _Rp (_FnType) (_Param..., ...);
2922};
2923
2924template <class _Rp, class _Class, class ..._Param>
2925struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&, true, false>
2926{
2927    typedef _Class volatile& _ClassType;
2928    typedef _Rp _ReturnType;
2929    typedef _Rp (_FnType) (_Param...);
2930};
2931
2932template <class _Rp, class _Class, class ..._Param>
2933struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&, true, false>
2934{
2935    typedef _Class volatile& _ClassType;
2936    typedef _Rp _ReturnType;
2937    typedef _Rp (_FnType) (_Param..., ...);
2938};
2939
2940template <class _Rp, class _Class, class ..._Param>
2941struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&, true, false>
2942{
2943    typedef _Class const volatile& _ClassType;
2944    typedef _Rp _ReturnType;
2945    typedef _Rp (_FnType) (_Param...);
2946};
2947
2948template <class _Rp, class _Class, class ..._Param>
2949struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&, true, false>
2950{
2951    typedef _Class const volatile& _ClassType;
2952    typedef _Rp _ReturnType;
2953    typedef _Rp (_FnType) (_Param..., ...);
2954};
2955
2956template <class _Rp, class _Class, class ..._Param>
2957struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) &&, true, false>
2958{
2959    typedef _Class&& _ClassType;
2960    typedef _Rp _ReturnType;
2961    typedef _Rp (_FnType) (_Param...);
2962};
2963
2964template <class _Rp, class _Class, class ..._Param>
2965struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) &&, true, false>
2966{
2967    typedef _Class&& _ClassType;
2968    typedef _Rp _ReturnType;
2969    typedef _Rp (_FnType) (_Param..., ...);
2970};
2971
2972template <class _Rp, class _Class, class ..._Param>
2973struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const&&, true, false>
2974{
2975    typedef _Class const&& _ClassType;
2976    typedef _Rp _ReturnType;
2977    typedef _Rp (_FnType) (_Param...);
2978};
2979
2980template <class _Rp, class _Class, class ..._Param>
2981struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const&&, true, false>
2982{
2983    typedef _Class const&& _ClassType;
2984    typedef _Rp _ReturnType;
2985    typedef _Rp (_FnType) (_Param..., ...);
2986};
2987
2988template <class _Rp, class _Class, class ..._Param>
2989struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) volatile&&, true, false>
2990{
2991    typedef _Class volatile&& _ClassType;
2992    typedef _Rp _ReturnType;
2993    typedef _Rp (_FnType) (_Param...);
2994};
2995
2996template <class _Rp, class _Class, class ..._Param>
2997struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) volatile&&, true, false>
2998{
2999    typedef _Class volatile&& _ClassType;
3000    typedef _Rp _ReturnType;
3001    typedef _Rp (_FnType) (_Param..., ...);
3002};
3003
3004template <class _Rp, class _Class, class ..._Param>
3005struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param...) const volatile&&, true, false>
3006{
3007    typedef _Class const volatile&& _ClassType;
3008    typedef _Rp _ReturnType;
3009    typedef _Rp (_FnType) (_Param...);
3010};
3011
3012template <class _Rp, class _Class, class ..._Param>
3013struct __member_pointer_traits_imp<_Rp (_Class::*)(_Param..., ...) const volatile&&, true, false>
3014{
3015    typedef _Class const volatile&& _ClassType;
3016    typedef _Rp _ReturnType;
3017    typedef _Rp (_FnType) (_Param..., ...);
3018};
3019
3020#endif  // __has_feature(cxx_reference_qualified_functions) || defined(_LIBCPP_COMPILER_GCC)
3021
3022
3023template <class _Rp, class _Class>
3024struct __member_pointer_traits_imp<_Rp _Class::*, false, true>
3025{
3026    typedef _Class _ClassType;
3027    typedef _Rp _ReturnType;
3028};
3029
3030template <class _MP>
3031struct __member_pointer_traits
3032    : public __member_pointer_traits_imp<typename remove_cv<_MP>::type,
3033                    is_member_function_pointer<_MP>::value,
3034                    is_member_object_pointer<_MP>::value>
3035{
3036//     typedef ... _ClassType;
3037//     typedef ... _ReturnType;
3038//     typedef ... _FnType;
3039};
3040
3041
3042template <class _DecayedFp>
3043struct __member_pointer_class_type {};
3044
3045template <class _Ret, class _ClassType>
3046struct __member_pointer_class_type<_Ret _ClassType::*> {
3047  typedef _ClassType type;
3048};
3049
3050// template <class T, class... Args> struct is_constructible;
3051
3052#if defined(_LIBCPP_COMPILER_GCC) && _GNUC_VER_NEW >= 10000
3053# define _LIBCPP_GCC_SUPPORTS_IS_CONSTRUCTIBLE
3054#endif
3055
3056#if !defined(_LIBCPP_CXX03_LANG) && !__has_feature(is_constructible) && !defined(_LIBCPP_GCC_SUPPORTS_IS_CONSTRUCTIBLE)
3057
3058template <class _Tp, class... _Args>
3059struct __libcpp_is_constructible;
3060
3061template <class _To, class _From>
3062struct __is_invalid_base_to_derived_cast {
3063  static_assert(is_reference<_To>::value, "Wrong specialization");
3064  using _RawFrom = __uncvref_t<_From>;
3065  using _RawTo = __uncvref_t<_To>;
3066  static const bool value = _And<
3067        _IsNotSame<_RawFrom, _RawTo>,
3068        is_base_of<_RawFrom, _RawTo>,
3069        _Not<__libcpp_is_constructible<_RawTo, _From>>
3070  >::value;
3071};
3072
3073template <class _To, class _From>
3074struct __is_invalid_lvalue_to_rvalue_cast : false_type {
3075  static_assert(is_reference<_To>::value, "Wrong specialization");
3076};
3077
3078template <class _ToRef, class _FromRef>
3079struct __is_invalid_lvalue_to_rvalue_cast<_ToRef&&, _FromRef&> {
3080  using _RawFrom = __uncvref_t<_FromRef>;
3081  using _RawTo = __uncvref_t<_ToRef>;
3082  static const bool value = _And<
3083      _Not<is_function<_RawTo>>,
3084      _Or<
3085        _IsSame<_RawFrom, _RawTo>,
3086        is_base_of<_RawTo, _RawFrom>>
3087    >::value;
3088};
3089
3090struct __is_constructible_helper
3091{
3092    template <class _To>
3093    static void __eat(_To);
3094
3095    // This overload is needed to work around a Clang bug that disallows
3096    // static_cast<T&&>(e) for non-reference-compatible types.
3097    // Example: static_cast<int&&>(declval<double>());
3098    // NOTE: The static_cast implementation below is required to support
3099    //  classes with explicit conversion operators.
3100    template <class _To, class _From,
3101              class = decltype(__eat<_To>(_VSTD::declval<_From>()))>
3102    static true_type __test_cast(int);
3103
3104    template <class _To, class _From,
3105              class = decltype(static_cast<_To>(_VSTD::declval<_From>()))>
3106    static integral_constant<bool,
3107        !__is_invalid_base_to_derived_cast<_To, _From>::value &&
3108        !__is_invalid_lvalue_to_rvalue_cast<_To, _From>::value
3109    > __test_cast(long);
3110
3111    template <class, class>
3112    static false_type __test_cast(...);
3113
3114    template <class _Tp, class ..._Args,
3115        class = decltype(_Tp(_VSTD::declval<_Args>()...))>
3116    static true_type __test_nary(int);
3117    template <class _Tp, class...>
3118    static false_type __test_nary(...);
3119
3120    template <class _Tp, class _A0, class = decltype(::new _Tp(_VSTD::declval<_A0>()))>
3121    static is_destructible<_Tp> __test_unary(int);
3122    template <class, class>
3123    static false_type __test_unary(...);
3124};
3125
3126template <class _Tp, bool = is_void<_Tp>::value>
3127struct __is_default_constructible
3128    : decltype(__is_constructible_helper::__test_nary<_Tp>(0))
3129{};
3130
3131template <class _Tp>
3132struct __is_default_constructible<_Tp, true> : false_type {};
3133
3134template <class _Tp>
3135struct __is_default_constructible<_Tp[], false> : false_type {};
3136
3137template <class _Tp, size_t _Nx>
3138struct __is_default_constructible<_Tp[_Nx], false>
3139    : __is_default_constructible<typename remove_all_extents<_Tp>::type>  {};
3140
3141template <class _Tp, class... _Args>
3142struct __libcpp_is_constructible
3143{
3144  static_assert(sizeof...(_Args) > 1, "Wrong specialization");
3145  typedef decltype(__is_constructible_helper::__test_nary<_Tp, _Args...>(0))
3146      type;
3147};
3148
3149template <class _Tp>
3150struct __libcpp_is_constructible<_Tp> : __is_default_constructible<_Tp> {};
3151
3152template <class _Tp, class _A0>
3153struct __libcpp_is_constructible<_Tp, _A0>
3154    : public decltype(__is_constructible_helper::__test_unary<_Tp, _A0>(0))
3155{};
3156
3157template <class _Tp, class _A0>
3158struct __libcpp_is_constructible<_Tp&, _A0>
3159    : public decltype(__is_constructible_helper::
3160    __test_cast<_Tp&, _A0>(0))
3161{};
3162
3163template <class _Tp, class _A0>
3164struct __libcpp_is_constructible<_Tp&&, _A0>
3165    : public decltype(__is_constructible_helper::
3166    __test_cast<_Tp&&, _A0>(0))
3167{};
3168
3169#endif
3170
3171#if __has_feature(is_constructible) || defined(_LIBCPP_GCC_SUPPORTS_IS_CONSTRUCTIBLE)
3172template <class _Tp, class ..._Args>
3173struct _LIBCPP_TEMPLATE_VIS is_constructible
3174    : public integral_constant<bool, __is_constructible(_Tp, _Args...)>
3175    {};
3176#else
3177template <class _Tp, class... _Args>
3178struct _LIBCPP_TEMPLATE_VIS is_constructible
3179    : public __libcpp_is_constructible<_Tp, _Args...>::type {};
3180#endif
3181
3182#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3183template <class _Tp, class ..._Args>
3184_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_constructible_v
3185    = is_constructible<_Tp, _Args...>::value;
3186#endif
3187
3188// is_default_constructible
3189
3190template <class _Tp>
3191struct _LIBCPP_TEMPLATE_VIS is_default_constructible
3192    : public is_constructible<_Tp>
3193    {};
3194
3195#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3196template <class _Tp>
3197_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_default_constructible_v
3198    = is_default_constructible<_Tp>::value;
3199#endif
3200
3201#ifndef _LIBCPP_CXX03_LANG
3202// First of all, we can't implement this check in C++03 mode because the {}
3203// default initialization syntax isn't valid.
3204// Second, we implement the trait in a funny manner with two defaulted template
3205// arguments to workaround Clang's PR43454.
3206template <class _Tp>
3207void __test_implicit_default_constructible(_Tp);
3208
3209template <class _Tp, class = void, bool = is_default_constructible<_Tp>::value>
3210struct __is_implicitly_default_constructible
3211    : false_type
3212{ };
3213
3214template <class _Tp>
3215struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), true>
3216    : true_type
3217{ };
3218
3219template <class _Tp>
3220struct __is_implicitly_default_constructible<_Tp, decltype(__test_implicit_default_constructible<_Tp const&>({})), false>
3221    : false_type
3222{ };
3223#endif // !C++03
3224
3225// is_copy_constructible
3226
3227template <class _Tp>
3228struct _LIBCPP_TEMPLATE_VIS is_copy_constructible
3229    : public is_constructible<_Tp,
3230                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3231
3232#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3233template <class _Tp>
3234_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_copy_constructible_v
3235    = is_copy_constructible<_Tp>::value;
3236#endif
3237
3238// is_move_constructible
3239
3240template <class _Tp>
3241struct _LIBCPP_TEMPLATE_VIS is_move_constructible
3242    : public is_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3243    {};
3244
3245#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3246template <class _Tp>
3247_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_move_constructible_v
3248    = is_move_constructible<_Tp>::value;
3249#endif
3250
3251// is_trivially_constructible
3252
3253#if __has_feature(is_trivially_constructible) || _GNUC_VER >= 501
3254
3255template <class _Tp, class... _Args>
3256struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible
3257    : integral_constant<bool, __is_trivially_constructible(_Tp, _Args...)>
3258{
3259};
3260
3261#else  // !__has_feature(is_trivially_constructible)
3262
3263template <class _Tp, class... _Args>
3264struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible
3265    : false_type
3266{
3267};
3268
3269template <class _Tp>
3270struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp>
3271#if __has_feature(has_trivial_constructor) || defined(_LIBCPP_COMPILER_GCC)
3272    : integral_constant<bool, __has_trivial_constructor(_Tp)>
3273#else
3274    : integral_constant<bool, is_scalar<_Tp>::value>
3275#endif
3276{
3277};
3278
3279template <class _Tp>
3280struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, _Tp&&>
3281    : integral_constant<bool, is_scalar<_Tp>::value>
3282{
3283};
3284
3285template <class _Tp>
3286struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, const _Tp&>
3287    : integral_constant<bool, is_scalar<_Tp>::value>
3288{
3289};
3290
3291template <class _Tp>
3292struct _LIBCPP_TEMPLATE_VIS is_trivially_constructible<_Tp, _Tp&>
3293    : integral_constant<bool, is_scalar<_Tp>::value>
3294{
3295};
3296
3297#endif  // !__has_feature(is_trivially_constructible)
3298
3299
3300#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3301template <class _Tp, class... _Args>
3302_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_constructible_v
3303    = is_trivially_constructible<_Tp, _Args...>::value;
3304#endif
3305
3306// is_trivially_default_constructible
3307
3308template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_default_constructible
3309    : public is_trivially_constructible<_Tp>
3310    {};
3311
3312#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3313template <class _Tp>
3314_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_default_constructible_v
3315    = is_trivially_default_constructible<_Tp>::value;
3316#endif
3317
3318// is_trivially_copy_constructible
3319
3320template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_constructible
3321    : public is_trivially_constructible<_Tp, typename add_lvalue_reference<const _Tp>::type>
3322    {};
3323
3324#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3325template <class _Tp>
3326_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copy_constructible_v
3327    = is_trivially_copy_constructible<_Tp>::value;
3328#endif
3329
3330// is_trivially_move_constructible
3331
3332template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_constructible
3333    : public is_trivially_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3334    {};
3335
3336#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3337template <class _Tp>
3338_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_move_constructible_v
3339    = is_trivially_move_constructible<_Tp>::value;
3340#endif
3341
3342// is_trivially_assignable
3343
3344#if __has_feature(is_trivially_assignable) || _GNUC_VER >= 501
3345
3346template <class _Tp, class _Arg>
3347struct is_trivially_assignable
3348    : integral_constant<bool, __is_trivially_assignable(_Tp, _Arg)>
3349{
3350};
3351
3352#else  // !__has_feature(is_trivially_assignable)
3353
3354template <class _Tp, class _Arg>
3355struct is_trivially_assignable
3356    : public false_type {};
3357
3358template <class _Tp>
3359struct is_trivially_assignable<_Tp&, _Tp>
3360    : integral_constant<bool, is_scalar<_Tp>::value> {};
3361
3362template <class _Tp>
3363struct is_trivially_assignable<_Tp&, _Tp&>
3364    : integral_constant<bool, is_scalar<_Tp>::value> {};
3365
3366template <class _Tp>
3367struct is_trivially_assignable<_Tp&, const _Tp&>
3368    : integral_constant<bool, is_scalar<_Tp>::value> {};
3369
3370template <class _Tp>
3371struct is_trivially_assignable<_Tp&, _Tp&&>
3372    : integral_constant<bool, is_scalar<_Tp>::value> {};
3373
3374#endif  // !__has_feature(is_trivially_assignable)
3375
3376#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3377template <class _Tp, class _Arg>
3378_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_assignable_v
3379    = is_trivially_assignable<_Tp, _Arg>::value;
3380#endif
3381
3382// is_trivially_copy_assignable
3383
3384template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copy_assignable
3385    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3386                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3387
3388#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3389template <class _Tp>
3390_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copy_assignable_v
3391    = is_trivially_copy_assignable<_Tp>::value;
3392#endif
3393
3394// is_trivially_move_assignable
3395
3396template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_move_assignable
3397    : public is_trivially_assignable<typename add_lvalue_reference<_Tp>::type,
3398                                     typename add_rvalue_reference<_Tp>::type>
3399    {};
3400
3401#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3402template <class _Tp>
3403_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_move_assignable_v
3404    = is_trivially_move_assignable<_Tp>::value;
3405#endif
3406
3407// is_trivially_destructible
3408
3409#if __has_keyword(__is_trivially_destructible)
3410
3411template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3412    : public integral_constant<bool, __is_trivially_destructible(_Tp)> {};
3413
3414#elif __has_feature(has_trivial_destructor) || defined(_LIBCPP_COMPILER_GCC)
3415
3416template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3417    : public integral_constant<bool, is_destructible<_Tp>::value && __has_trivial_destructor(_Tp)> {};
3418
3419#else
3420
3421template <class _Tp> struct __libcpp_trivial_destructor
3422    : public integral_constant<bool, is_scalar<_Tp>::value ||
3423                                     is_reference<_Tp>::value> {};
3424
3425template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible
3426    : public __libcpp_trivial_destructor<typename remove_all_extents<_Tp>::type> {};
3427
3428template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_destructible<_Tp[]>
3429    : public false_type {};
3430
3431#endif
3432
3433#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3434template <class _Tp>
3435_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_destructible_v
3436    = is_trivially_destructible<_Tp>::value;
3437#endif
3438
3439// is_nothrow_constructible
3440
3441#if __has_keyword(__is_nothrow_constructible)
3442
3443template <class _Tp, class... _Args>
3444struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3445    : public integral_constant<bool, __is_nothrow_constructible(_Tp, _Args...)> {};
3446
3447#else
3448
3449template <bool, bool, class _Tp, class... _Args> struct __libcpp_is_nothrow_constructible;
3450
3451template <class _Tp, class... _Args>
3452struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/false, _Tp, _Args...>
3453    : public integral_constant<bool, noexcept(_Tp(declval<_Args>()...))>
3454{
3455};
3456
3457template <class _Tp>
3458void __implicit_conversion_to(_Tp) noexcept { }
3459
3460template <class _Tp, class _Arg>
3461struct __libcpp_is_nothrow_constructible</*is constructible*/true, /*is reference*/true, _Tp, _Arg>
3462    : public integral_constant<bool, noexcept(_VSTD::__implicit_conversion_to<_Tp>(declval<_Arg>()))>
3463{
3464};
3465
3466template <class _Tp, bool _IsReference, class... _Args>
3467struct __libcpp_is_nothrow_constructible</*is constructible*/false, _IsReference, _Tp, _Args...>
3468    : public false_type
3469{
3470};
3471
3472template <class _Tp, class... _Args>
3473struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible
3474    : __libcpp_is_nothrow_constructible<is_constructible<_Tp, _Args...>::value, is_reference<_Tp>::value, _Tp, _Args...>
3475{
3476};
3477
3478template <class _Tp, size_t _Ns>
3479struct _LIBCPP_TEMPLATE_VIS is_nothrow_constructible<_Tp[_Ns]>
3480    : __libcpp_is_nothrow_constructible<is_constructible<_Tp>::value, is_reference<_Tp>::value, _Tp>
3481{
3482};
3483
3484#endif  // _LIBCPP_HAS_NO_NOEXCEPT
3485
3486
3487#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3488template <class _Tp, class ..._Args>
3489_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_constructible_v
3490    = is_nothrow_constructible<_Tp, _Args...>::value;
3491#endif
3492
3493// is_nothrow_default_constructible
3494
3495template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_default_constructible
3496    : public is_nothrow_constructible<_Tp>
3497    {};
3498
3499#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3500template <class _Tp>
3501_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_default_constructible_v
3502    = is_nothrow_default_constructible<_Tp>::value;
3503#endif
3504
3505// is_nothrow_copy_constructible
3506
3507template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_constructible
3508    : public is_nothrow_constructible<_Tp,
3509                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3510
3511#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3512template <class _Tp>
3513_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_copy_constructible_v
3514    = is_nothrow_copy_constructible<_Tp>::value;
3515#endif
3516
3517// is_nothrow_move_constructible
3518
3519template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_constructible
3520    : public is_nothrow_constructible<_Tp, typename add_rvalue_reference<_Tp>::type>
3521    {};
3522
3523#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3524template <class _Tp>
3525_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_move_constructible_v
3526    = is_nothrow_move_constructible<_Tp>::value;
3527#endif
3528
3529// is_nothrow_assignable
3530
3531#if __has_keyword(__is_nothrow_assignable)
3532
3533template <class _Tp, class _Arg>
3534struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3535    : public integral_constant<bool, __is_nothrow_assignable(_Tp, _Arg)> {};
3536
3537#else
3538
3539template <bool, class _Tp, class _Arg> struct __libcpp_is_nothrow_assignable;
3540
3541template <class _Tp, class _Arg>
3542struct __libcpp_is_nothrow_assignable<false, _Tp, _Arg>
3543    : public false_type
3544{
3545};
3546
3547template <class _Tp, class _Arg>
3548struct __libcpp_is_nothrow_assignable<true, _Tp, _Arg>
3549    : public integral_constant<bool, noexcept(_VSTD::declval<_Tp>() = _VSTD::declval<_Arg>()) >
3550{
3551};
3552
3553template <class _Tp, class _Arg>
3554struct _LIBCPP_TEMPLATE_VIS is_nothrow_assignable
3555    : public __libcpp_is_nothrow_assignable<is_assignable<_Tp, _Arg>::value, _Tp, _Arg>
3556{
3557};
3558
3559#endif  // _LIBCPP_HAS_NO_NOEXCEPT
3560
3561#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3562template <class _Tp, class _Arg>
3563_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_assignable_v
3564    = is_nothrow_assignable<_Tp, _Arg>::value;
3565#endif
3566
3567// is_nothrow_copy_assignable
3568
3569template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_copy_assignable
3570    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3571                  typename add_lvalue_reference<typename add_const<_Tp>::type>::type> {};
3572
3573#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3574template <class _Tp>
3575_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_copy_assignable_v
3576    = is_nothrow_copy_assignable<_Tp>::value;
3577#endif
3578
3579// is_nothrow_move_assignable
3580
3581template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_move_assignable
3582    : public is_nothrow_assignable<typename add_lvalue_reference<_Tp>::type,
3583                                     typename add_rvalue_reference<_Tp>::type>
3584    {};
3585
3586#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3587template <class _Tp>
3588_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_move_assignable_v
3589    = is_nothrow_move_assignable<_Tp>::value;
3590#endif
3591
3592// is_nothrow_destructible
3593
3594#if !defined(_LIBCPP_CXX03_LANG)
3595
3596template <bool, class _Tp> struct __libcpp_is_nothrow_destructible;
3597
3598template <class _Tp>
3599struct __libcpp_is_nothrow_destructible<false, _Tp>
3600    : public false_type
3601{
3602};
3603
3604template <class _Tp>
3605struct __libcpp_is_nothrow_destructible<true, _Tp>
3606    : public integral_constant<bool, noexcept(_VSTD::declval<_Tp>().~_Tp()) >
3607{
3608};
3609
3610template <class _Tp>
3611struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3612    : public __libcpp_is_nothrow_destructible<is_destructible<_Tp>::value, _Tp>
3613{
3614};
3615
3616template <class _Tp, size_t _Ns>
3617struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[_Ns]>
3618    : public is_nothrow_destructible<_Tp>
3619{
3620};
3621
3622template <class _Tp>
3623struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&>
3624    : public true_type
3625{
3626};
3627
3628template <class _Tp>
3629struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp&&>
3630    : public true_type
3631{
3632};
3633
3634#else
3635
3636template <class _Tp> struct __libcpp_nothrow_destructor
3637    : public integral_constant<bool, is_scalar<_Tp>::value ||
3638                                     is_reference<_Tp>::value> {};
3639
3640template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible
3641    : public __libcpp_nothrow_destructor<typename remove_all_extents<_Tp>::type> {};
3642
3643template <class _Tp>
3644struct _LIBCPP_TEMPLATE_VIS is_nothrow_destructible<_Tp[]>
3645    : public false_type {};
3646
3647#endif
3648
3649#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3650template <class _Tp>
3651_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_nothrow_destructible_v
3652    = is_nothrow_destructible<_Tp>::value;
3653#endif
3654
3655// is_pod
3656
3657#if __has_feature(is_pod) || defined(_LIBCPP_COMPILER_GCC)
3658
3659template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3660    : public integral_constant<bool, __is_pod(_Tp)> {};
3661
3662#else
3663
3664template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_pod
3665    : public integral_constant<bool, is_trivially_default_constructible<_Tp>::value   &&
3666                                     is_trivially_copy_constructible<_Tp>::value      &&
3667                                     is_trivially_copy_assignable<_Tp>::value    &&
3668                                     is_trivially_destructible<_Tp>::value> {};
3669
3670#endif
3671
3672#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3673template <class _Tp>
3674_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_pod_v
3675    = is_pod<_Tp>::value;
3676#endif
3677
3678// is_literal_type;
3679
3680template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_literal_type
3681    : public integral_constant<bool, __is_literal_type(_Tp)>
3682    {};
3683
3684#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3685template <class _Tp>
3686_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_literal_type_v
3687    = is_literal_type<_Tp>::value;
3688#endif
3689
3690// is_standard_layout;
3691
3692template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_standard_layout
3693#if __has_feature(is_standard_layout) || defined(_LIBCPP_COMPILER_GCC)
3694    : public integral_constant<bool, __is_standard_layout(_Tp)>
3695#else
3696    : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value>
3697#endif
3698    {};
3699
3700#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3701template <class _Tp>
3702_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_standard_layout_v
3703    = is_standard_layout<_Tp>::value;
3704#endif
3705
3706// is_trivially_copyable;
3707
3708template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivially_copyable
3709#if __has_feature(is_trivially_copyable)
3710    : public integral_constant<bool, __is_trivially_copyable(_Tp)>
3711#elif _GNUC_VER >= 501
3712    : public integral_constant<bool, !is_volatile<_Tp>::value && __is_trivially_copyable(_Tp)>
3713#else
3714    : integral_constant<bool, is_scalar<typename remove_all_extents<_Tp>::type>::value>
3715#endif
3716    {};
3717
3718#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3719template <class _Tp>
3720_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivially_copyable_v
3721    = is_trivially_copyable<_Tp>::value;
3722#endif
3723
3724// is_trivial;
3725
3726template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_trivial
3727#if __has_feature(is_trivial) || defined(_LIBCPP_COMPILER_GCC)
3728    : public integral_constant<bool, __is_trivial(_Tp)>
3729#else
3730    : integral_constant<bool, is_trivially_copyable<_Tp>::value &&
3731                                 is_trivially_default_constructible<_Tp>::value>
3732#endif
3733    {};
3734
3735#if _LIBCPP_STD_VER > 14 && !defined(_LIBCPP_HAS_NO_VARIABLE_TEMPLATES)
3736template <class _Tp>
3737_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_trivial_v
3738    = is_trivial<_Tp>::value;
3739#endif
3740
3741template <class _Tp> struct __is_reference_wrapper_impl : public false_type {};
3742template <class _Tp> struct __is_reference_wrapper_impl<reference_wrapper<_Tp> > : public true_type {};
3743template <class _Tp> struct __is_reference_wrapper
3744    : public __is_reference_wrapper_impl<typename remove_cv<_Tp>::type> {};
3745
3746#ifndef _LIBCPP_CXX03_LANG
3747
3748template <class _Fp, class _A0,
3749         class _DecayFp = typename decay<_Fp>::type,
3750         class _DecayA0 = typename decay<_A0>::type,
3751         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3752using __enable_if_bullet1 = typename enable_if
3753    <
3754        is_member_function_pointer<_DecayFp>::value
3755        && is_base_of<_ClassT, _DecayA0>::value
3756    >::type;
3757
3758template <class _Fp, class _A0,
3759         class _DecayFp = typename decay<_Fp>::type,
3760         class _DecayA0 = typename decay<_A0>::type>
3761using __enable_if_bullet2 = typename enable_if
3762    <
3763        is_member_function_pointer<_DecayFp>::value
3764        && __is_reference_wrapper<_DecayA0>::value
3765    >::type;
3766
3767template <class _Fp, class _A0,
3768         class _DecayFp = typename decay<_Fp>::type,
3769         class _DecayA0 = typename decay<_A0>::type,
3770         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3771using __enable_if_bullet3 = typename enable_if
3772    <
3773        is_member_function_pointer<_DecayFp>::value
3774        && !is_base_of<_ClassT, _DecayA0>::value
3775        && !__is_reference_wrapper<_DecayA0>::value
3776    >::type;
3777
3778template <class _Fp, class _A0,
3779         class _DecayFp = typename decay<_Fp>::type,
3780         class _DecayA0 = typename decay<_A0>::type,
3781         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3782using __enable_if_bullet4 = typename enable_if
3783    <
3784        is_member_object_pointer<_DecayFp>::value
3785        && is_base_of<_ClassT, _DecayA0>::value
3786    >::type;
3787
3788template <class _Fp, class _A0,
3789         class _DecayFp = typename decay<_Fp>::type,
3790         class _DecayA0 = typename decay<_A0>::type>
3791using __enable_if_bullet5 = typename enable_if
3792    <
3793        is_member_object_pointer<_DecayFp>::value
3794        && __is_reference_wrapper<_DecayA0>::value
3795    >::type;
3796
3797template <class _Fp, class _A0,
3798         class _DecayFp = typename decay<_Fp>::type,
3799         class _DecayA0 = typename decay<_A0>::type,
3800         class _ClassT = typename __member_pointer_class_type<_DecayFp>::type>
3801using __enable_if_bullet6 = typename enable_if
3802    <
3803        is_member_object_pointer<_DecayFp>::value
3804        && !is_base_of<_ClassT, _DecayA0>::value
3805        && !__is_reference_wrapper<_DecayA0>::value
3806    >::type;
3807
3808// __invoke forward declarations
3809
3810// fall back - none of the bullets
3811
3812#define _LIBCPP_INVOKE_RETURN(...) \
3813    noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__) \
3814    { return __VA_ARGS__; }
3815
3816template <class ..._Args>
3817auto __invoke(__any, _Args&& ...__args) -> __nat;
3818
3819template <class ..._Args>
3820auto __invoke_constexpr(__any, _Args&& ...__args) -> __nat;
3821
3822// bullets 1, 2 and 3
3823
3824template <class _Fp, class _A0, class ..._Args,
3825          class = __enable_if_bullet1<_Fp, _A0>>
3826inline _LIBCPP_INLINE_VISIBILITY
3827_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3828__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3829_LIBCPP_INVOKE_RETURN((_VSTD::forward<_A0>(__a0).*__f)(_VSTD::forward<_Args>(__args)...))
3830
3831template <class _Fp, class _A0, class ..._Args,
3832          class = __enable_if_bullet1<_Fp, _A0>>
3833inline _LIBCPP_INLINE_VISIBILITY
3834_LIBCPP_CONSTEXPR auto
3835__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3836_LIBCPP_INVOKE_RETURN((_VSTD::forward<_A0>(__a0).*__f)(_VSTD::forward<_Args>(__args)...))
3837
3838template <class _Fp, class _A0, class ..._Args,
3839          class = __enable_if_bullet2<_Fp, _A0>>
3840inline _LIBCPP_INLINE_VISIBILITY
3841_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3842__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3843_LIBCPP_INVOKE_RETURN((__a0.get().*__f)(_VSTD::forward<_Args>(__args)...))
3844
3845template <class _Fp, class _A0, class ..._Args,
3846          class = __enable_if_bullet2<_Fp, _A0>>
3847inline _LIBCPP_INLINE_VISIBILITY
3848_LIBCPP_CONSTEXPR auto
3849__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3850_LIBCPP_INVOKE_RETURN((__a0.get().*__f)(_VSTD::forward<_Args>(__args)...))
3851
3852template <class _Fp, class _A0, class ..._Args,
3853          class = __enable_if_bullet3<_Fp, _A0>>
3854inline _LIBCPP_INLINE_VISIBILITY
3855_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3856__invoke(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3857_LIBCPP_INVOKE_RETURN(((*_VSTD::forward<_A0>(__a0)).*__f)(_VSTD::forward<_Args>(__args)...))
3858
3859template <class _Fp, class _A0, class ..._Args,
3860          class = __enable_if_bullet3<_Fp, _A0>>
3861inline _LIBCPP_INLINE_VISIBILITY
3862_LIBCPP_CONSTEXPR auto
3863__invoke_constexpr(_Fp&& __f, _A0&& __a0, _Args&& ...__args)
3864_LIBCPP_INVOKE_RETURN(((*_VSTD::forward<_A0>(__a0)).*__f)(_VSTD::forward<_Args>(__args)...))
3865
3866// bullets 4, 5 and 6
3867
3868template <class _Fp, class _A0,
3869          class = __enable_if_bullet4<_Fp, _A0>>
3870inline _LIBCPP_INLINE_VISIBILITY
3871_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3872__invoke(_Fp&& __f, _A0&& __a0)
3873_LIBCPP_INVOKE_RETURN(_VSTD::forward<_A0>(__a0).*__f)
3874
3875template <class _Fp, class _A0,
3876          class = __enable_if_bullet4<_Fp, _A0>>
3877inline _LIBCPP_INLINE_VISIBILITY
3878_LIBCPP_CONSTEXPR auto
3879__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3880_LIBCPP_INVOKE_RETURN(_VSTD::forward<_A0>(__a0).*__f)
3881
3882template <class _Fp, class _A0,
3883          class = __enable_if_bullet5<_Fp, _A0>>
3884inline _LIBCPP_INLINE_VISIBILITY
3885_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3886__invoke(_Fp&& __f, _A0&& __a0)
3887_LIBCPP_INVOKE_RETURN(__a0.get().*__f)
3888
3889template <class _Fp, class _A0,
3890          class = __enable_if_bullet5<_Fp, _A0>>
3891inline _LIBCPP_INLINE_VISIBILITY
3892_LIBCPP_CONSTEXPR auto
3893__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3894_LIBCPP_INVOKE_RETURN(__a0.get().*__f)
3895
3896template <class _Fp, class _A0,
3897          class = __enable_if_bullet6<_Fp, _A0>>
3898inline _LIBCPP_INLINE_VISIBILITY
3899_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3900__invoke(_Fp&& __f, _A0&& __a0)
3901_LIBCPP_INVOKE_RETURN((*_VSTD::forward<_A0>(__a0)).*__f)
3902
3903template <class _Fp, class _A0,
3904          class = __enable_if_bullet6<_Fp, _A0>>
3905inline _LIBCPP_INLINE_VISIBILITY
3906_LIBCPP_CONSTEXPR auto
3907__invoke_constexpr(_Fp&& __f, _A0&& __a0)
3908_LIBCPP_INVOKE_RETURN((*_VSTD::forward<_A0>(__a0)).*__f)
3909
3910// bullet 7
3911
3912template <class _Fp, class ..._Args>
3913inline _LIBCPP_INLINE_VISIBILITY
3914_LIBCPP_CONSTEXPR_AFTER_CXX17 auto
3915__invoke(_Fp&& __f, _Args&& ...__args)
3916_LIBCPP_INVOKE_RETURN(_VSTD::forward<_Fp>(__f)(_VSTD::forward<_Args>(__args)...))
3917
3918template <class _Fp, class ..._Args>
3919inline _LIBCPP_INLINE_VISIBILITY
3920_LIBCPP_CONSTEXPR auto
3921__invoke_constexpr(_Fp&& __f, _Args&& ...__args)
3922_LIBCPP_INVOKE_RETURN(_VSTD::forward<_Fp>(__f)(_VSTD::forward<_Args>(__args)...))
3923
3924#undef _LIBCPP_INVOKE_RETURN
3925
3926// __invokable
3927template <class _Ret, class _Fp, class ..._Args>
3928struct __invokable_r
3929{
3930  template <class _XFp, class ..._XArgs>
3931  static auto __try_call(int) -> decltype(
3932    _VSTD::__invoke(_VSTD::declval<_XFp>(), _VSTD::declval<_XArgs>()...));
3933  template <class _XFp, class ..._XArgs>
3934  static __nat __try_call(...);
3935
3936  // FIXME: Check that _Ret, _Fp, and _Args... are all complete types, cv void,
3937  // or incomplete array types as required by the standard.
3938  using _Result = decltype(__try_call<_Fp, _Args...>(0));
3939
3940  using type =
3941  typename conditional<
3942      _IsNotSame<_Result, __nat>::value,
3943      typename conditional<
3944          is_void<_Ret>::value,
3945          true_type,
3946          is_convertible<_Result, _Ret>
3947      >::type,
3948      false_type
3949  >::type;
3950  static const bool value = type::value;
3951};
3952template <class _Fp, class ..._Args>
3953using __invokable = __invokable_r<void, _Fp, _Args...>;
3954
3955template <bool _IsInvokable, bool _IsCVVoid, class _Ret, class _Fp, class ..._Args>
3956struct __nothrow_invokable_r_imp {
3957  static const bool value = false;
3958};
3959
3960template <class _Ret, class _Fp, class ..._Args>
3961struct __nothrow_invokable_r_imp<true, false, _Ret, _Fp, _Args...>
3962{
3963    typedef __nothrow_invokable_r_imp _ThisT;
3964
3965    template <class _Tp>
3966    static void __test_noexcept(_Tp) noexcept;
3967
3968    static const bool value = noexcept(_ThisT::__test_noexcept<_Ret>(
3969        _VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...)));
3970};
3971
3972template <class _Ret, class _Fp, class ..._Args>
3973struct __nothrow_invokable_r_imp<true, true, _Ret, _Fp, _Args...>
3974{
3975    static const bool value = noexcept(
3976        _VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...));
3977};
3978
3979template <class _Ret, class _Fp, class ..._Args>
3980using __nothrow_invokable_r =
3981    __nothrow_invokable_r_imp<
3982            __invokable_r<_Ret, _Fp, _Args...>::value,
3983            is_void<_Ret>::value,
3984            _Ret, _Fp, _Args...
3985    >;
3986
3987template <class _Fp, class ..._Args>
3988using __nothrow_invokable =
3989    __nothrow_invokable_r_imp<
3990            __invokable<_Fp, _Args...>::value,
3991            true, void, _Fp, _Args...
3992    >;
3993
3994template <class _Fp, class ..._Args>
3995struct __invoke_of
3996    : public enable_if<
3997        __invokable<_Fp, _Args...>::value,
3998        typename __invokable_r<void, _Fp, _Args...>::_Result>
3999{
4000};
4001
4002#endif // _LIBCPP_CXX03_LANG
4003
4004// result_of
4005
4006template <class _Callable> class result_of;
4007
4008#ifndef _LIBCPP_CXX03_LANG
4009
4010template <class _Fp, class ..._Args>
4011class _LIBCPP_TEMPLATE_VIS result_of<_Fp(_Args...)>
4012    : public __invoke_of<_Fp, _Args...>
4013{
4014};
4015
4016#else // C++03
4017
4018template <class _Fn, bool, bool>
4019class __result_of
4020{
4021};
4022
4023template <class _Fn, class ..._Args>
4024class __result_of<_Fn(_Args...), true, false>
4025{
4026public:
4027    typedef decltype(declval<_Fn>()(declval<_Args>()...)) type;
4028};
4029
4030template <class _MP, class _Tp, bool _IsMemberFunctionPtr>
4031struct __result_of_mp;
4032
4033// member function pointer
4034
4035template <class _MP, class _Tp>
4036struct __result_of_mp<_MP, _Tp, true>
4037{
4038    using type = typename __member_pointer_traits<_MP>::_ReturnType;
4039};
4040
4041// member data pointer
4042
4043template <class _MP, class _Tp, bool>
4044struct __result_of_mdp;
4045
4046template <class _Rp, class _Class, class _Tp>
4047struct __result_of_mdp<_Rp _Class::*, _Tp, false>
4048{
4049    using type = typename __apply_cv<decltype(*_VSTD::declval<_Tp>()), _Rp>::type&;
4050};
4051
4052template <class _Rp, class _Class, class _Tp>
4053struct __result_of_mdp<_Rp _Class::*, _Tp, true>
4054{
4055    using type = typename __apply_cv<_Tp, _Rp>::type&;
4056};
4057
4058template <class _Rp, class _Class, class _Tp>
4059struct __result_of_mp<_Rp _Class::*, _Tp, false>
4060    : public __result_of_mdp<_Rp _Class::*, _Tp,
4061            is_base_of<_Class, typename remove_reference<_Tp>::type>::value>
4062{
4063};
4064
4065template <class _Fn, class _Tp>
4066class __result_of<_Fn(_Tp), false, true>  // _Fn must be member pointer
4067    : public __result_of_mp<typename remove_reference<_Fn>::type,
4068                            _Tp,
4069                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
4070{
4071};
4072
4073template <class _Fn, class _Tp, class ..._Args>
4074class __result_of<_Fn(_Tp, _Args...), false, true>  // _Fn must be member pointer
4075    : public __result_of_mp<typename remove_reference<_Fn>::type,
4076                            _Tp,
4077                            is_member_function_pointer<typename remove_reference<_Fn>::type>::value>
4078{
4079};
4080
4081template <class _Fn, class ..._Args>
4082class _LIBCPP_TEMPLATE_VIS result_of<_Fn(_Args...)>
4083    : public __result_of<_Fn(_Args...),
4084                         is_class<typename remove_reference<_Fn>::type>::value ||
4085                         is_function<typename remove_pointer<typename remove_reference<_Fn>::type>::type>::value,
4086                         is_member_pointer<typename remove_reference<_Fn>::type>::value
4087                        >
4088{
4089};
4090
4091#endif  // C++03
4092
4093#if _LIBCPP_STD_VER > 11
4094template <class _Tp> using result_of_t = typename result_of<_Tp>::type;
4095#endif
4096
4097#if _LIBCPP_STD_VER > 14
4098
4099// invoke_result
4100
4101template <class _Fn, class... _Args>
4102struct _LIBCPP_TEMPLATE_VIS invoke_result
4103    : __invoke_of<_Fn, _Args...>
4104{
4105};
4106
4107template <class _Fn, class... _Args>
4108using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
4109
4110// is_invocable
4111
4112template <class _Fn, class ..._Args>
4113struct _LIBCPP_TEMPLATE_VIS is_invocable
4114    : integral_constant<bool, __invokable<_Fn, _Args...>::value> {};
4115
4116template <class _Ret, class _Fn, class ..._Args>
4117struct _LIBCPP_TEMPLATE_VIS is_invocable_r
4118    : integral_constant<bool, __invokable_r<_Ret, _Fn, _Args...>::value> {};
4119
4120template <class _Fn, class ..._Args>
4121_LIBCPP_INLINE_VAR constexpr bool is_invocable_v
4122    = is_invocable<_Fn, _Args...>::value;
4123
4124template <class _Ret, class _Fn, class ..._Args>
4125_LIBCPP_INLINE_VAR constexpr bool is_invocable_r_v
4126    = is_invocable_r<_Ret, _Fn, _Args...>::value;
4127
4128// is_nothrow_invocable
4129
4130template <class _Fn, class ..._Args>
4131struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable
4132    : integral_constant<bool, __nothrow_invokable<_Fn, _Args...>::value> {};
4133
4134template <class _Ret, class _Fn, class ..._Args>
4135struct _LIBCPP_TEMPLATE_VIS is_nothrow_invocable_r
4136    : integral_constant<bool, __nothrow_invokable_r<_Ret, _Fn, _Args...>::value> {};
4137
4138template <class _Fn, class ..._Args>
4139_LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_v
4140    = is_nothrow_invocable<_Fn, _Args...>::value;
4141
4142template <class _Ret, class _Fn, class ..._Args>
4143_LIBCPP_INLINE_VAR constexpr bool is_nothrow_invocable_r_v
4144    = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
4145
4146#endif // _LIBCPP_STD_VER > 14
4147
4148template <class _Tp> struct __is_swappable;
4149template <class _Tp> struct __is_nothrow_swappable;
4150
4151// swap, swap_ranges
4152
4153template <class _ForwardIterator1, class _ForwardIterator2>
4154inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4155_ForwardIterator2
4156swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2);
4157
4158template <class _Tp>
4159inline _LIBCPP_INLINE_VISIBILITY
4160#ifndef _LIBCPP_CXX03_LANG
4161typename enable_if
4162<
4163    is_move_constructible<_Tp>::value &&
4164    is_move_assignable<_Tp>::value
4165>::type
4166#else
4167void
4168#endif
4169_LIBCPP_CONSTEXPR_AFTER_CXX17
4170swap(_Tp& __x, _Tp& __y) _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value &&
4171                                    is_nothrow_move_assignable<_Tp>::value)
4172{
4173    _Tp __t(_VSTD::move(__x));
4174    __x = _VSTD::move(__y);
4175    __y = _VSTD::move(__t);
4176}
4177
4178template<class _Tp, size_t _Np>
4179inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4180typename enable_if<
4181    __is_swappable<_Tp>::value
4182>::type
4183swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value)
4184{
4185    _VSTD::swap_ranges(__a, __a + _Np, __b);
4186}
4187
4188template <class _ForwardIterator1, class _ForwardIterator2>
4189inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4190_ForwardIterator2
4191swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
4192{
4193    for(; __first1 != __last1; ++__first1, (void) ++__first2)
4194        swap(*__first1, *__first2);
4195    return __first2;
4196}
4197
4198// iter_swap
4199
4200template <class _ForwardIterator1, class _ForwardIterator2>
4201inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4202void
4203iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
4204    //                                  _NOEXCEPT_(_NOEXCEPT_(swap(*__a, *__b)))
4205               _NOEXCEPT_(_NOEXCEPT_(swap(*_VSTD::declval<_ForwardIterator1>(),
4206                                          *_VSTD::declval<_ForwardIterator2>())))
4207{
4208    swap(*__a, *__b);
4209}
4210
4211// __swappable
4212
4213namespace __detail
4214{
4215// ALL generic swap overloads MUST already have a declaration available at this point.
4216
4217template <class _Tp, class _Up = _Tp,
4218          bool _NotVoid = !is_void<_Tp>::value && !is_void<_Up>::value>
4219struct __swappable_with
4220{
4221    template <class _LHS, class _RHS>
4222    static decltype(swap(_VSTD::declval<_LHS>(), _VSTD::declval<_RHS>()))
4223    __test_swap(int);
4224    template <class, class>
4225    static __nat __test_swap(long);
4226
4227    // Extra parens are needed for the C++03 definition of decltype.
4228    typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
4229    typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;
4230
4231    static const bool value = _IsNotSame<__swap1, __nat>::value
4232                           && _IsNotSame<__swap2, __nat>::value;
4233};
4234
4235template <class _Tp, class _Up>
4236struct __swappable_with<_Tp, _Up,  false> : false_type {};
4237
4238template <class _Tp, class _Up = _Tp, bool _Swappable = __swappable_with<_Tp, _Up>::value>
4239struct __nothrow_swappable_with {
4240  static const bool value =
4241#ifndef _LIBCPP_HAS_NO_NOEXCEPT
4242      noexcept(swap(_VSTD::declval<_Tp>(), _VSTD::declval<_Up>()))
4243  &&  noexcept(swap(_VSTD::declval<_Up>(), _VSTD::declval<_Tp>()));
4244#else
4245      false;
4246#endif
4247};
4248
4249template <class _Tp, class _Up>
4250struct __nothrow_swappable_with<_Tp, _Up, false> : false_type {};
4251
4252}  // __detail
4253
4254template <class _Tp>
4255struct __is_swappable
4256    : public integral_constant<bool, __detail::__swappable_with<_Tp&>::value>
4257{
4258};
4259
4260template <class _Tp>
4261struct __is_nothrow_swappable
4262    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp&>::value>
4263{
4264};
4265
4266#if _LIBCPP_STD_VER > 14
4267
4268template <class _Tp, class _Up>
4269struct _LIBCPP_TEMPLATE_VIS is_swappable_with
4270    : public integral_constant<bool, __detail::__swappable_with<_Tp, _Up>::value>
4271{
4272};
4273
4274template <class _Tp>
4275struct _LIBCPP_TEMPLATE_VIS is_swappable
4276    : public conditional<
4277        __is_referenceable<_Tp>::value,
4278        is_swappable_with<
4279            typename add_lvalue_reference<_Tp>::type,
4280            typename add_lvalue_reference<_Tp>::type>,
4281        false_type
4282    >::type
4283{
4284};
4285
4286template <class _Tp, class _Up>
4287struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable_with
4288    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp, _Up>::value>
4289{
4290};
4291
4292template <class _Tp>
4293struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable
4294    : public conditional<
4295        __is_referenceable<_Tp>::value,
4296        is_nothrow_swappable_with<
4297            typename add_lvalue_reference<_Tp>::type,
4298            typename add_lvalue_reference<_Tp>::type>,
4299        false_type
4300    >::type
4301{
4302};
4303
4304template <class _Tp, class _Up>
4305_LIBCPP_INLINE_VAR constexpr bool is_swappable_with_v
4306    = is_swappable_with<_Tp, _Up>::value;
4307
4308template <class _Tp>
4309_LIBCPP_INLINE_VAR constexpr bool is_swappable_v
4310    = is_swappable<_Tp>::value;
4311
4312template <class _Tp, class _Up>
4313_LIBCPP_INLINE_VAR constexpr bool is_nothrow_swappable_with_v
4314    = is_nothrow_swappable_with<_Tp, _Up>::value;
4315
4316template <class _Tp>
4317_LIBCPP_INLINE_VAR constexpr bool is_nothrow_swappable_v
4318    = is_nothrow_swappable<_Tp>::value;
4319
4320#endif // _LIBCPP_STD_VER > 14
4321
4322template <class _Tp, bool = is_enum<_Tp>::value> struct __underlying_type_impl;
4323
4324template <class _Tp>
4325struct __underlying_type_impl<_Tp, false> {};
4326
4327template <class _Tp>
4328struct __underlying_type_impl<_Tp, true>
4329{
4330    typedef __underlying_type(_Tp) type;
4331};
4332
4333template <class _Tp>
4334struct underlying_type : __underlying_type_impl<_Tp, is_enum<_Tp>::value> {};
4335
4336#if _LIBCPP_STD_VER > 11
4337template <class _Tp> using underlying_type_t = typename underlying_type<_Tp>::type;
4338#endif
4339
4340template <class _Tp, bool = is_enum<_Tp>::value>
4341struct __sfinae_underlying_type
4342{
4343    typedef typename underlying_type<_Tp>::type type;
4344    typedef decltype(((type)1) + 0) __promoted_type;
4345};
4346
4347template <class _Tp>
4348struct __sfinae_underlying_type<_Tp, false> {};
4349
4350inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4351int __convert_to_integral(int __val) { return __val; }
4352
4353inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4354unsigned __convert_to_integral(unsigned __val) { return __val; }
4355
4356inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4357long __convert_to_integral(long __val) { return __val; }
4358
4359inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4360unsigned long __convert_to_integral(unsigned long __val) { return __val; }
4361
4362inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4363long long __convert_to_integral(long long __val) { return __val; }
4364
4365inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4366unsigned long long __convert_to_integral(unsigned long long __val) {return __val; }
4367
4368template<typename _Fp>
4369inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4370typename enable_if<is_floating_point<_Fp>::value, long long>::type
4371 __convert_to_integral(_Fp __val) { return __val; }
4372
4373#ifndef _LIBCPP_HAS_NO_INT128
4374inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4375__int128_t __convert_to_integral(__int128_t __val) { return __val; }
4376
4377inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4378__uint128_t __convert_to_integral(__uint128_t __val) { return __val; }
4379#endif
4380
4381template <class _Tp>
4382inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
4383typename __sfinae_underlying_type<_Tp>::__promoted_type
4384__convert_to_integral(_Tp __val) { return __val; }
4385
4386#ifndef _LIBCPP_CXX03_LANG
4387
4388template <class _Tp>
4389struct __has_operator_addressof_member_imp
4390{
4391    template <class _Up>
4392        static auto __test(int)
4393            -> typename __select_2nd<decltype(_VSTD::declval<_Up>().operator&()), true_type>::type;
4394    template <class>
4395        static auto __test(long) -> false_type;
4396
4397    static const bool value = decltype(__test<_Tp>(0))::value;
4398};
4399
4400template <class _Tp>
4401struct __has_operator_addressof_free_imp
4402{
4403    template <class _Up>
4404        static auto __test(int)
4405            -> typename __select_2nd<decltype(operator&(_VSTD::declval<_Up>())), true_type>::type;
4406    template <class>
4407        static auto __test(long) -> false_type;
4408
4409    static const bool value = decltype(__test<_Tp>(0))::value;
4410};
4411
4412template <class _Tp>
4413struct __has_operator_addressof
4414    : public integral_constant<bool, __has_operator_addressof_member_imp<_Tp>::value
4415                                  || __has_operator_addressof_free_imp<_Tp>::value>
4416{};
4417
4418#endif  // _LIBCPP_CXX03_LANG
4419
4420// is_scoped_enum [meta.unary.prop]
4421
4422#if _LIBCPP_STD_VER > 20
4423template <class _Tp, bool = is_enum_v<_Tp> >
4424struct __is_scoped_enum_helper : false_type {};
4425
4426template <class _Tp>
4427struct __is_scoped_enum_helper<_Tp, true>
4428    : public bool_constant<!is_convertible_v<_Tp, underlying_type_t<_Tp> > > {};
4429
4430template <class _Tp>
4431struct _LIBCPP_TEMPLATE_VIS is_scoped_enum
4432    : public __is_scoped_enum_helper<_Tp> {};
4433
4434template <class _Tp>
4435_LIBCPP_INLINE_VAR _LIBCPP_CONSTEXPR bool is_scoped_enum_v =
4436    is_scoped_enum<_Tp>::value;
4437#endif
4438
4439#if _LIBCPP_STD_VER > 14
4440
4441template <class... _Args>
4442struct conjunction : _And<_Args...> {};
4443template<class... _Args>
4444_LIBCPP_INLINE_VAR constexpr bool conjunction_v
4445    = conjunction<_Args...>::value;
4446
4447template <class... _Args>
4448struct disjunction : _Or<_Args...> {};
4449template<class... _Args>
4450_LIBCPP_INLINE_VAR constexpr bool disjunction_v
4451    = disjunction<_Args...>::value;
4452
4453template <class _Tp>
4454struct negation : _Not<_Tp> {};
4455template<class _Tp>
4456_LIBCPP_INLINE_VAR constexpr bool negation_v
4457    = negation<_Tp>::value;
4458#endif  // _LIBCPP_STD_VER > 14
4459
4460// These traits are used in __tree and __hash_table
4461struct __extract_key_fail_tag {};
4462struct __extract_key_self_tag {};
4463struct __extract_key_first_tag {};
4464
4465template <class _ValTy, class _Key,
4466          class _RawValTy = typename __unconstref<_ValTy>::type>
4467struct __can_extract_key
4468    : conditional<_IsSame<_RawValTy, _Key>::value, __extract_key_self_tag,
4469                  __extract_key_fail_tag>::type {};
4470
4471template <class _Pair, class _Key, class _First, class _Second>
4472struct __can_extract_key<_Pair, _Key, pair<_First, _Second> >
4473    : conditional<_IsSame<typename remove_const<_First>::type, _Key>::value,
4474                  __extract_key_first_tag, __extract_key_fail_tag>::type {};
4475
4476// __can_extract_map_key uses true_type/false_type instead of the tags.
4477// It returns true if _Key != _ContainerValueTy (the container is a map not a set)
4478// and _ValTy == _Key.
4479template <class _ValTy, class _Key, class _ContainerValueTy,
4480          class _RawValTy = typename __unconstref<_ValTy>::type>
4481struct __can_extract_map_key
4482    : integral_constant<bool, _IsSame<_RawValTy, _Key>::value> {};
4483
4484// This specialization returns __extract_key_fail_tag for non-map containers
4485// because _Key == _ContainerValueTy
4486template <class _ValTy, class _Key, class _RawValTy>
4487struct __can_extract_map_key<_ValTy, _Key, _Key, _RawValTy>
4488    : false_type {};
4489
4490#ifndef _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED
4491#if _LIBCPP_STD_VER > 17
4492_LIBCPP_INLINE_VISIBILITY
4493inline constexpr bool is_constant_evaluated() noexcept {
4494  return __builtin_is_constant_evaluated();
4495}
4496#endif
4497
4498inline _LIBCPP_CONSTEXPR
4499bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
4500#else
4501inline _LIBCPP_CONSTEXPR
4502bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; }
4503#endif
4504
4505template <class _CharT>
4506using _IsCharLikeType = _And<is_standard_layout<_CharT>, is_trivial<_CharT> >;
4507
4508template<class _Tp>
4509using __make_const_lvalue_ref = const typename remove_reference<_Tp>::type&;
4510
4511_LIBCPP_END_NAMESPACE_STD
4512
4513#if _LIBCPP_STD_VER > 14
4514// std::byte
4515namespace std  // purposefully not versioned
4516{
4517
4518
4519}
4520#endif
4521
4522#endif  // _LIBCPP_TYPE_TRAITS
4523