xref: /llvm-project/libcxx/include/type_traits (revision b9a2658a3e8bd13b0f9e7a8a440832a95b377216)
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_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++23
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; // Deprecated in C++17; removed in C++20
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 is_implicit_lifetime;                     // Since C++23
141
142    template <class T> struct has_virtual_destructor;
143
144    template<class T> struct has_unique_object_representations;         // C++17
145
146    // Relationships between types:
147    template <class T, class U> struct is_same;
148    template <class Base, class Derived> struct is_base_of;
149    template <class Base, class Derived> struct is_virtual_base_of;     // C++26
150
151    template <class From, class To> struct is_convertible;
152    template <typename From, typename To> struct is_nothrow_convertible;                  // C++20
153    template <typename From, typename To> inline constexpr bool is_nothrow_convertible_v; // C++20
154
155    template <class Fn, class... ArgTypes> struct is_invocable;
156    template <class R, class Fn, class... ArgTypes> struct is_invocable_r;
157
158    template <class Fn, class... ArgTypes> struct is_nothrow_invocable;
159    template <class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r;
160
161    // Alignment properties and transformations:
162    template <class T> struct alignment_of;
163    template <size_t Len, size_t Align = most_stringent_alignment_requirement>
164        struct aligned_storage;                                 // deprecated in C++23
165    template <size_t Len, class... Types> struct aligned_union; // deprecated in C++23
166    template <class T> struct remove_cvref; // C++20
167
168    template <class T> struct decay;
169    template <class... T> struct common_type;
170    template <class T> struct underlying_type;
171    template <class> class result_of; // undefined; deprecated in C++17; removed in C++20
172    template <class Fn, class... ArgTypes> class result_of<Fn(ArgTypes...)>; // deprecated in C++17; removed in C++20
173    template <class Fn, class... ArgTypes> struct invoke_result;  // C++17
174
175    // const-volatile modifications:
176    template <class T>
177      using remove_const_t    = typename remove_const<T>::type;  // C++14
178    template <class T>
179      using remove_volatile_t = typename remove_volatile<T>::type;  // C++14
180    template <class T>
181      using remove_cv_t       = typename remove_cv<T>::type;  // C++14
182    template <class T>
183      using add_const_t       = typename add_const<T>::type;  // C++14
184    template <class T>
185      using add_volatile_t    = typename add_volatile<T>::type;  // C++14
186    template <class T>
187      using add_cv_t          = typename add_cv<T>::type;  // C++14
188
189    // reference modifications:
190    template <class T>
191      using remove_reference_t     = typename remove_reference<T>::type;  // C++14
192    template <class T>
193      using add_lvalue_reference_t = typename add_lvalue_reference<T>::type;  // C++14
194    template <class T>
195      using add_rvalue_reference_t = typename add_rvalue_reference<T>::type;  // C++14
196
197    // sign modifications:
198    template <class T>
199      using make_signed_t   = typename make_signed<T>::type;  // C++14
200    template <class T>
201      using make_unsigned_t = typename make_unsigned<T>::type;  // C++14
202
203    // array modifications:
204    template <class T>
205      using remove_extent_t      = typename remove_extent<T>::type;  // C++14
206    template <class T>
207      using remove_all_extents_t = typename remove_all_extents<T>::type;  // C++14
208
209    template <class T>
210      inline constexpr bool is_bounded_array_v
211        = is_bounded_array<T>::value;                                     // C++20
212      inline constexpr bool is_unbounded_array_v
213        = is_unbounded_array<T>::value;                                   // C++20
214
215    // pointer modifications:
216    template <class T>
217      using remove_pointer_t = typename remove_pointer<T>::type;  // C++14
218    template <class T>
219      using add_pointer_t    = typename add_pointer<T>::type;  // C++14
220
221    // other transformations:
222    template <size_t Len, size_t Align=default-alignment>
223      using aligned_storage_t = typename aligned_storage<Len,Align>::type;  // C++14
224    template <size_t Len, class... Types>
225      using aligned_union_t   = typename aligned_union<Len,Types...>::type;  // C++14
226    template <class T>
227      using remove_cvref_t    = typename remove_cvref<T>::type;  // C++20
228    template <class T>
229      using decay_t           = typename decay<T>::type;  // C++14
230    template <bool b, class T=void>
231      using enable_if_t       = typename enable_if<b,T>::type;  // C++14
232    template <bool b, class T, class F>
233      using conditional_t     = typename conditional<b,T,F>::type;  // C++14
234    template <class... T>
235      using common_type_t     = typename common_type<T...>::type;  // C++14
236    template <class T>
237      using underlying_type_t = typename underlying_type<T>::type;  // C++14
238    template <class T>
239      using result_of_t       = typename result_of<T>::type;  // C++14; deprecated in C++17; removed in C++20
240    template <class Fn, class... ArgTypes>
241      using invoke_result_t   = typename invoke_result<Fn, ArgTypes...>::type;  // C++17
242
243    template <class...>
244      using void_t = void;   // C++17
245
246      // See C++14 20.10.4.1, primary type categories
247      template <class T> inline constexpr bool is_void_v
248        = is_void<T>::value;                                             // C++17
249      template <class T> inline constexpr bool is_null_pointer_v
250        = is_null_pointer<T>::value;                                     // C++17
251      template <class T> inline constexpr bool is_integral_v
252        = is_integral<T>::value;                                         // C++17
253      template <class T> inline constexpr bool is_floating_point_v
254        = is_floating_point<T>::value;                                   // C++17
255      template <class T> inline constexpr bool is_array_v
256        = is_array<T>::value;                                            // C++17
257      template <class T> inline constexpr bool is_pointer_v
258        = is_pointer<T>::value;                                          // C++17
259      template <class T> inline constexpr bool is_lvalue_reference_v
260        = is_lvalue_reference<T>::value;                                 // C++17
261      template <class T> inline constexpr bool is_rvalue_reference_v
262        = is_rvalue_reference<T>::value;                                 // C++17
263      template <class T> inline constexpr bool is_member_object_pointer_v
264        = is_member_object_pointer<T>::value;                            // C++17
265      template <class T> inline constexpr bool is_member_function_pointer_v
266        = is_member_function_pointer<T>::value;                          // C++17
267      template <class T> inline constexpr bool is_enum_v
268        = is_enum<T>::value;                                             // C++17
269      template <class T> inline constexpr bool is_union_v
270        = is_union<T>::value;                                            // C++17
271      template <class T> inline constexpr bool is_class_v
272        = is_class<T>::value;                                            // C++17
273      template <class T> inline constexpr bool is_function_v
274        = is_function<T>::value;                                         // C++17
275
276      // See C++14 20.10.4.2, composite type categories
277      template <class T> inline constexpr bool is_reference_v
278        = is_reference<T>::value;                                        // C++17
279      template <class T> inline constexpr bool is_arithmetic_v
280        = is_arithmetic<T>::value;                                       // C++17
281      template <class T> inline constexpr bool is_fundamental_v
282        = is_fundamental<T>::value;                                      // C++17
283      template <class T> inline constexpr bool is_object_v
284        = is_object<T>::value;                                           // C++17
285      template <class T> inline constexpr bool is_scalar_v
286        = is_scalar<T>::value;                                           // C++17
287      template <class T> inline constexpr bool is_compound_v
288        = is_compound<T>::value;                                         // C++17
289      template <class T> inline constexpr bool is_member_pointer_v
290        = is_member_pointer<T>::value;                                   // C++17
291      template <class T> inline constexpr bool is_scoped_enum_v
292        = is_scoped_enum<T>::value;                                      // C++23
293
294      // See C++14 20.10.4.3, type properties
295      template <class T> inline constexpr bool is_const_v
296        = is_const<T>::value;                                            // C++17
297      template <class T> inline constexpr bool is_volatile_v
298        = is_volatile<T>::value;                                         // C++17
299      template <class T> inline constexpr bool is_trivial_v
300        = is_trivial<T>::value;                                          // C++17
301      template <class T> inline constexpr bool is_trivially_copyable_v
302        = is_trivially_copyable<T>::value;                               // C++17
303      template <class T> inline constexpr bool is_standard_layout_v
304        = is_standard_layout<T>::value;                                  // C++17
305      template <class T> inline constexpr bool is_pod_v
306        = is_pod<T>::value;                                              // C++17
307      template <class T> inline constexpr bool is_literal_type_v
308        = is_literal_type<T>::value;                                     // C++17; deprecated in C++17; removed in C++20
309      template <class T> inline constexpr bool is_empty_v
310        = is_empty<T>::value;                                            // C++17
311      template <class T> inline constexpr bool is_polymorphic_v
312        = is_polymorphic<T>::value;                                      // C++17
313      template <class T> inline constexpr bool is_abstract_v
314        = is_abstract<T>::value;                                         // C++17
315      template <class T> inline constexpr bool is_final_v
316        = is_final<T>::value;                                            // C++17
317      template <class T> inline constexpr bool is_aggregate_v
318        = is_aggregate<T>::value;                                        // C++17
319      template <class T> inline constexpr bool is_signed_v
320        = is_signed<T>::value;                                           // C++17
321      template <class T> inline constexpr bool is_unsigned_v
322        = is_unsigned<T>::value;                                         // C++17
323      template <class T, class... Args> inline constexpr bool is_constructible_v
324        = is_constructible<T, Args...>::value;                           // C++17
325      template <class T> inline constexpr bool is_default_constructible_v
326        = is_default_constructible<T>::value;                            // C++17
327      template <class T> inline constexpr bool is_copy_constructible_v
328        = is_copy_constructible<T>::value;                               // C++17
329      template <class T> inline constexpr bool is_move_constructible_v
330        = is_move_constructible<T>::value;                               // C++17
331      template <class T, class U> inline constexpr bool is_assignable_v
332        = is_assignable<T, U>::value;                                    // C++17
333      template <class T> inline constexpr bool is_copy_assignable_v
334        = is_copy_assignable<T>::value;                                  // C++17
335      template <class T> inline constexpr bool is_move_assignable_v
336        = is_move_assignable<T>::value;                                  // C++17
337      template <class T, class U> inline constexpr bool is_swappable_with_v
338        = is_swappable_with<T, U>::value;                                // C++17
339      template <class T> inline constexpr bool is_swappable_v
340        = is_swappable<T>::value;                                        // C++17
341      template <class T> inline constexpr bool is_destructible_v
342        = is_destructible<T>::value;                                     // C++17
343      template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
344        = is_trivially_constructible<T, Args...>::value;                 // C++17
345      template <class T> inline constexpr bool is_trivially_default_constructible_v
346        = is_trivially_default_constructible<T>::value;                  // C++17
347      template <class T> inline constexpr bool is_trivially_copy_constructible_v
348        = is_trivially_copy_constructible<T>::value;                     // C++17
349      template <class T> inline constexpr bool is_trivially_move_constructible_v
350        = is_trivially_move_constructible<T>::value;                     // C++17
351      template <class T, class U> inline constexpr bool is_trivially_assignable_v
352        = is_trivially_assignable<T, U>::value;                          // C++17
353      template <class T> inline constexpr bool is_trivially_copy_assignable_v
354        = is_trivially_copy_assignable<T>::value;                        // C++17
355      template <class T> inline constexpr bool is_trivially_move_assignable_v
356        = is_trivially_move_assignable<T>::value;                        // C++17
357      template <class T> inline constexpr bool is_trivially_destructible_v
358        = is_trivially_destructible<T>::value;                           // C++17
359      template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
360        = is_nothrow_constructible<T, Args...>::value;                   // C++17
361      template <class T> inline constexpr bool is_nothrow_default_constructible_v
362        = is_nothrow_default_constructible<T>::value;                    // C++17
363      template <class T> inline constexpr bool is_nothrow_copy_constructible_v
364        = is_nothrow_copy_constructible<T>::value;                       // C++17
365      template <class T> inline constexpr bool is_nothrow_move_constructible_v
366        = is_nothrow_move_constructible<T>::value;                       // C++17
367      template <class T, class U> inline constexpr bool is_nothrow_assignable_v
368        = is_nothrow_assignable<T, U>::value;                            // C++17
369      template <class T> inline constexpr bool is_nothrow_copy_assignable_v
370        = is_nothrow_copy_assignable<T>::value;                          // C++17
371      template <class T> inline constexpr bool is_nothrow_move_assignable_v
372        = is_nothrow_move_assignable<T>::value;                          // C++17
373      template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
374        = is_nothrow_swappable_with<T, U>::value;                       // C++17
375      template <class T> inline constexpr bool is_nothrow_swappable_v
376        = is_nothrow_swappable<T>::value;                               // C++17
377      template <class T> inline constexpr bool is_nothrow_destructible_v
378        = is_nothrow_destructible<T>::value;                             // C++17
379      template<class T>
380        constexpr bool is_implicit_lifetime_v = is_implicit_lifetime<T>::value;   // Since C++23
381      template <class T> inline constexpr bool has_virtual_destructor_v
382        = has_virtual_destructor<T>::value;                              // C++17
383      template<class T> inline constexpr bool has_unique_object_representations_v // C++17
384        = has_unique_object_representations<T>::value;
385
386      // See C++14 20.10.5, type property queries
387      template <class T> inline constexpr size_t alignment_of_v
388        = alignment_of<T>::value;                                        // C++17
389      template <class T> inline constexpr size_t rank_v
390        = rank<T>::value;                                                // C++17
391      template <class T, unsigned I = 0> inline constexpr size_t extent_v
392        = extent<T, I>::value;                                           // C++17
393
394      // See C++14 20.10.6, type relations
395      template <class T, class U> inline constexpr bool is_same_v
396        = is_same<T, U>::value;                                          // C++17
397      template <class Base, class Derived> inline constexpr bool is_base_of_v
398        = is_base_of<Base, Derived>::value;                              // C++17
399      template <class Base, class Derived> inline constexpr bool is_virtual_base_of_v
400        = is_virtual_base_of<Base, Derived>::value;                      // C++26
401      template <class From, class To> inline constexpr bool is_convertible_v
402        = is_convertible<From, To>::value;                               // C++17
403      template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
404        = is_invocable<Fn, ArgTypes...>::value;                          // C++17
405      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
406        = is_invocable_r<R, Fn, ArgTypes...>::value;                     // C++17
407      template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
408        = is_nothrow_invocable<Fn, ArgTypes...>::value;                  // C++17
409      template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
410        = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;             // C++17
411
412      // [meta.logical], logical operator traits:
413      template<class... B> struct conjunction;                           // C++17
414      template<class... B>
415        inline constexpr bool conjunction_v = conjunction<B...>::value;  // C++17
416      template<class... B> struct disjunction;                           // C++17
417      template<class... B>
418        inline constexpr bool disjunction_v = disjunction<B...>::value;  // C++17
419      template<class B> struct negation;                                 // C++17
420      template<class B>
421        inline constexpr bool negation_v = negation<B>::value;           // C++17
422
423}
424
425*/
426
427#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
428#  include <__cxx03/type_traits>
429#else
430#  include <__config>
431#  include <__type_traits/add_cv_quals.h>
432#  include <__type_traits/add_lvalue_reference.h>
433#  include <__type_traits/add_pointer.h>
434#  include <__type_traits/add_rvalue_reference.h>
435#  include <__type_traits/aligned_storage.h>
436#  include <__type_traits/aligned_union.h>
437#  include <__type_traits/alignment_of.h>
438#  include <__type_traits/common_type.h>
439#  include <__type_traits/conditional.h>
440#  include <__type_traits/decay.h>
441#  include <__type_traits/enable_if.h>
442#  include <__type_traits/extent.h>
443#  include <__type_traits/has_virtual_destructor.h>
444#  include <__type_traits/integral_constant.h>
445#  include <__type_traits/is_abstract.h>
446#  include <__type_traits/is_arithmetic.h>
447#  include <__type_traits/is_array.h>
448#  include <__type_traits/is_assignable.h>
449#  include <__type_traits/is_base_of.h>
450#  include <__type_traits/is_class.h>
451#  include <__type_traits/is_compound.h>
452#  include <__type_traits/is_const.h>
453#  include <__type_traits/is_constructible.h>
454#  include <__type_traits/is_convertible.h>
455#  include <__type_traits/is_destructible.h>
456#  include <__type_traits/is_empty.h>
457#  include <__type_traits/is_enum.h>
458#  include <__type_traits/is_floating_point.h>
459#  include <__type_traits/is_function.h>
460#  include <__type_traits/is_fundamental.h>
461#  include <__type_traits/is_integral.h>
462#  include <__type_traits/is_literal_type.h>
463#  include <__type_traits/is_member_pointer.h>
464#  include <__type_traits/is_nothrow_assignable.h>
465#  include <__type_traits/is_nothrow_constructible.h>
466#  include <__type_traits/is_nothrow_destructible.h>
467#  include <__type_traits/is_object.h>
468#  include <__type_traits/is_pod.h>
469#  include <__type_traits/is_pointer.h>
470#  include <__type_traits/is_polymorphic.h>
471#  include <__type_traits/is_reference.h>
472#  include <__type_traits/is_same.h>
473#  include <__type_traits/is_scalar.h>
474#  include <__type_traits/is_signed.h>
475#  include <__type_traits/is_standard_layout.h>
476#  include <__type_traits/is_trivial.h>
477#  include <__type_traits/is_trivially_assignable.h>
478#  include <__type_traits/is_trivially_constructible.h>
479#  include <__type_traits/is_trivially_copyable.h>
480#  include <__type_traits/is_trivially_destructible.h>
481#  include <__type_traits/is_union.h>
482#  include <__type_traits/is_unsigned.h>
483#  include <__type_traits/is_void.h>
484#  include <__type_traits/is_volatile.h>
485#  include <__type_traits/make_signed.h>
486#  include <__type_traits/make_unsigned.h>
487#  include <__type_traits/rank.h>
488#  include <__type_traits/remove_all_extents.h>
489#  include <__type_traits/remove_const.h>
490#  include <__type_traits/remove_cv.h>
491#  include <__type_traits/remove_extent.h>
492#  include <__type_traits/remove_pointer.h>
493#  include <__type_traits/remove_reference.h>
494#  include <__type_traits/remove_volatile.h>
495#  include <__type_traits/result_of.h>
496#  include <__type_traits/underlying_type.h>
497
498#  if _LIBCPP_STD_VER >= 14
499#    include <__type_traits/is_final.h>
500#    include <__type_traits/is_null_pointer.h>
501#  endif
502
503#  if _LIBCPP_STD_VER >= 17
504#    include <__type_traits/conjunction.h>
505#    include <__type_traits/disjunction.h>
506#    include <__type_traits/has_unique_object_representation.h>
507#    include <__type_traits/invoke.h>
508#    include <__type_traits/is_aggregate.h>
509#    include <__type_traits/is_swappable.h>
510#    include <__type_traits/negation.h>
511#    include <__type_traits/void_t.h>
512#  endif
513
514#  if _LIBCPP_STD_VER >= 20
515#    include <__type_traits/common_reference.h>
516#    include <__type_traits/is_bounded_array.h>
517#    include <__type_traits/is_constant_evaluated.h>
518#    include <__type_traits/is_nothrow_convertible.h>
519#    include <__type_traits/is_unbounded_array.h>
520#    include <__type_traits/type_identity.h>
521#    include <__type_traits/unwrap_ref.h>
522#  endif
523
524#  if _LIBCPP_STD_VER >= 23
525#    include <__type_traits/is_implicit_lifetime.h>
526#  endif
527
528#  include <version>
529
530#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
531#    pragma GCC system_header
532#  endif
533#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
534
535#endif // _LIBCPP_TYPE_TRAITS
536