libstdc++
type_traits
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1 // C++11 <type_traits> -*- C++ -*-
2 
3 // Copyright (C) 2007-2022 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file include/type_traits
26  * This is a Standard C++ Library header.
27  */
28 
29 #ifndef _GLIBCXX_TYPE_TRAITS
30 #define _GLIBCXX_TYPE_TRAITS 1
31 
32 #pragma GCC system_header
33 
34 #if __cplusplus < 201103L
35 # include <bits/c++0x_warning.h>
36 #else
37 
38 #include <bits/c++config.h>
39 
40 namespace std _GLIBCXX_VISIBILITY(default)
41 {
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 
44  template<typename _Tp>
45  class reference_wrapper;
46 
47  /**
48  * @defgroup metaprogramming Metaprogramming
49  * @ingroup utilities
50  *
51  * Template utilities for compile-time introspection and modification,
52  * including type classification traits, type property inspection traits
53  * and type transformation traits.
54  *
55  * @since C++11
56  *
57  * @{
58  */
59 
60  /// integral_constant
61  template<typename _Tp, _Tp __v>
63  {
64  static constexpr _Tp value = __v;
65  typedef _Tp value_type;
67  constexpr operator value_type() const noexcept { return value; }
68 #if __cplusplus > 201103L
69 
70 #define __cpp_lib_integral_constant_callable 201304L
71 
72  constexpr value_type operator()() const noexcept { return value; }
73 #endif
74  };
75 
76 #if ! __cpp_inline_variables
77  template<typename _Tp, _Tp __v>
79 #endif
80 
81  /// The type used as a compile-time boolean with true value.
83 
84  /// The type used as a compile-time boolean with false value.
86 
87  /// @cond undocumented
88  /// bool_constant for C++11
89  template<bool __v>
90  using __bool_constant = integral_constant<bool, __v>;
91  /// @endcond
92 
93 #if __cplusplus >= 201703L
94 # define __cpp_lib_bool_constant 201505L
95  /// Alias template for compile-time boolean constant types.
96  /// @since C++17
97  template<bool __v>
99 #endif
100 
101  // Metaprogramming helper types.
102 
103  template<bool>
104  struct __conditional
105  {
106  template<typename _Tp, typename>
107  using type = _Tp;
108  };
109 
110  template<>
111  struct __conditional<false>
112  {
113  template<typename, typename _Up>
114  using type = _Up;
115  };
116 
117  // More efficient version of std::conditional_t for internal use (and C++11)
118  template<bool _Cond, typename _If, typename _Else>
119  using __conditional_t
120  = typename __conditional<_Cond>::template type<_If, _Else>;
121 
122  /// @cond undocumented
123  template <typename _Type>
124  struct __type_identity
125  { using type = _Type; };
126 
127  template<typename _Tp>
128  using __type_identity_t = typename __type_identity<_Tp>::type;
129 
130  template<typename...>
131  struct __or_;
132 
133  template<>
134  struct __or_<>
135  : public false_type
136  { };
137 
138  template<typename _B1>
139  struct __or_<_B1>
140  : public _B1
141  { };
142 
143  template<typename _B1, typename _B2>
144  struct __or_<_B1, _B2>
145  : public __conditional_t<_B1::value, _B1, _B2>
146  { };
147 
148  template<typename _B1, typename _B2, typename _B3, typename... _Bn>
149  struct __or_<_B1, _B2, _B3, _Bn...>
150  : public __conditional_t<_B1::value, _B1, __or_<_B2, _B3, _Bn...>>
151  { };
152 
153  template<typename...>
154  struct __and_;
155 
156  template<>
157  struct __and_<>
158  : public true_type
159  { };
160 
161  template<typename _B1>
162  struct __and_<_B1>
163  : public _B1
164  { };
165 
166  template<typename _B1, typename _B2>
167  struct __and_<_B1, _B2>
168  : public __conditional_t<_B1::value, _B2, _B1>
169  { };
170 
171  template<typename _B1, typename _B2, typename _B3, typename... _Bn>
172  struct __and_<_B1, _B2, _B3, _Bn...>
173  : public __conditional_t<_B1::value, __and_<_B2, _B3, _Bn...>, _B1>
174  { };
175 
176  template<typename _Pp>
177  struct __not_
178  : public __bool_constant<!bool(_Pp::value)>
179  { };
180  /// @endcond
181 
182 #if __cplusplus >= 201703L
183 
184  /// @cond undocumented
185  template<typename... _Bn>
186  inline constexpr bool __or_v = __or_<_Bn...>::value;
187  template<typename... _Bn>
188  inline constexpr bool __and_v = __and_<_Bn...>::value;
189  /// @endcond
190 
191 #define __cpp_lib_logical_traits 201510L
192 
193  template<typename... _Bn>
194  struct conjunction
195  : __and_<_Bn...>
196  { };
197 
198  template<typename... _Bn>
199  struct disjunction
200  : __or_<_Bn...>
201  { };
202 
203  template<typename _Pp>
204  struct negation
205  : __not_<_Pp>
206  { };
207 
208  /** @ingroup variable_templates
209  * @{
210  */
211  template<typename... _Bn>
212  inline constexpr bool conjunction_v = conjunction<_Bn...>::value;
213 
214  template<typename... _Bn>
215  inline constexpr bool disjunction_v = disjunction<_Bn...>::value;
216 
217  template<typename _Pp>
218  inline constexpr bool negation_v = negation<_Pp>::value;
219  /// @}
220 
221 #endif // C++17
222 
223  // Forward declarations
224  template<typename>
225  struct is_reference;
226  template<typename>
227  struct is_function;
228  template<typename>
229  struct is_void;
230  template<typename>
231  struct remove_cv;
232  template<typename>
233  struct is_const;
234 
235  /// @cond undocumented
236  template<typename>
237  struct __is_array_unknown_bounds;
238 
239  // Helper functions that return false_type for incomplete classes,
240  // incomplete unions and arrays of known bound from those.
241 
242  template <typename _Tp, size_t = sizeof(_Tp)>
243  constexpr true_type __is_complete_or_unbounded(__type_identity<_Tp>)
244  { return {}; }
245 
246  template <typename _TypeIdentity,
247  typename _NestedType = typename _TypeIdentity::type>
248  constexpr typename __or_<
249  is_reference<_NestedType>,
250  is_function<_NestedType>,
251  is_void<_NestedType>,
252  __is_array_unknown_bounds<_NestedType>
253  >::type __is_complete_or_unbounded(_TypeIdentity)
254  { return {}; }
255 
256  // For several sfinae-friendly trait implementations we transport both the
257  // result information (as the member type) and the failure information (no
258  // member type). This is very similar to std::enable_if, but we cannot use
259  // them, because we need to derive from them as an implementation detail.
260 
261  template<typename _Tp>
262  struct __success_type
263  { typedef _Tp type; };
264 
265  struct __failure_type
266  { };
267 
268  // __remove_cv_t (std::remove_cv_t for C++11).
269  template<typename _Tp>
270  using __remove_cv_t = typename remove_cv<_Tp>::type;
271 
272  // Primary type categories.
273 
274  template<typename>
275  struct __is_void_helper
276  : public false_type { };
277 
278  template<>
279  struct __is_void_helper<void>
280  : public true_type { };
281  /// @endcond
282 
283  /// is_void
284  template<typename _Tp>
285  struct is_void
286  : public __is_void_helper<__remove_cv_t<_Tp>>::type
287  { };
288 
289  /// @cond undocumented
290  template<typename>
291  struct __is_integral_helper
292  : public false_type { };
293 
294  template<>
295  struct __is_integral_helper<bool>
296  : public true_type { };
297 
298  template<>
299  struct __is_integral_helper<char>
300  : public true_type { };
301 
302  template<>
303  struct __is_integral_helper<signed char>
304  : public true_type { };
305 
306  template<>
307  struct __is_integral_helper<unsigned char>
308  : public true_type { };
309 
310  // We want is_integral<wchar_t> to be true (and make_signed/unsigned to work)
311  // even when libc doesn't provide working <wchar.h> and related functions,
312  // so don't check _GLIBCXX_USE_WCHAR_T here.
313  template<>
314  struct __is_integral_helper<wchar_t>
315  : public true_type { };
316 
317 #ifdef _GLIBCXX_USE_CHAR8_T
318  template<>
319  struct __is_integral_helper<char8_t>
320  : public true_type { };
321 #endif
322 
323  template<>
324  struct __is_integral_helper<char16_t>
325  : public true_type { };
326 
327  template<>
328  struct __is_integral_helper<char32_t>
329  : public true_type { };
330 
331  template<>
332  struct __is_integral_helper<short>
333  : public true_type { };
334 
335  template<>
336  struct __is_integral_helper<unsigned short>
337  : public true_type { };
338 
339  template<>
340  struct __is_integral_helper<int>
341  : public true_type { };
342 
343  template<>
344  struct __is_integral_helper<unsigned int>
345  : public true_type { };
346 
347  template<>
348  struct __is_integral_helper<long>
349  : public true_type { };
350 
351  template<>
352  struct __is_integral_helper<unsigned long>
353  : public true_type { };
354 
355  template<>
356  struct __is_integral_helper<long long>
357  : public true_type { };
358 
359  template<>
360  struct __is_integral_helper<unsigned long long>
361  : public true_type { };
362 
363  // Conditionalizing on __STRICT_ANSI__ here will break any port that
364  // uses one of these types for size_t.
365 #if defined(__GLIBCXX_TYPE_INT_N_0)
366  __extension__
367  template<>
368  struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_0>
369  : public true_type { };
370 
371  __extension__
372  template<>
373  struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_0>
374  : public true_type { };
375 #endif
376 #if defined(__GLIBCXX_TYPE_INT_N_1)
377  __extension__
378  template<>
379  struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_1>
380  : public true_type { };
381 
382  __extension__
383  template<>
384  struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_1>
385  : public true_type { };
386 #endif
387 #if defined(__GLIBCXX_TYPE_INT_N_2)
388  __extension__
389  template<>
390  struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_2>
391  : public true_type { };
392 
393  __extension__
394  template<>
395  struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_2>
396  : public true_type { };
397 #endif
398 #if defined(__GLIBCXX_TYPE_INT_N_3)
399  __extension__
400  template<>
401  struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_3>
402  : public true_type { };
403 
404  __extension__
405  template<>
406  struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_3>
407  : public true_type { };
408 #endif
409  /// @endcond
410 
411  /// is_integral
412  template<typename _Tp>
413  struct is_integral
414  : public __is_integral_helper<__remove_cv_t<_Tp>>::type
415  { };
416 
417  /// @cond undocumented
418  template<typename>
419  struct __is_floating_point_helper
420  : public false_type { };
421 
422  template<>
423  struct __is_floating_point_helper<float>
424  : public true_type { };
425 
426  template<>
427  struct __is_floating_point_helper<double>
428  : public true_type { };
429 
430  template<>
431  struct __is_floating_point_helper<long double>
432  : public true_type { };
433 
434 #if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128) && !defined(__CUDACC__)
435  template<>
436  struct __is_floating_point_helper<__float128>
437  : public true_type { };
438 #endif
439  /// @endcond
440 
441  /// is_floating_point
442  template<typename _Tp>
444  : public __is_floating_point_helper<__remove_cv_t<_Tp>>::type
445  { };
446 
447  /// is_array
448  template<typename>
449  struct is_array
450  : public false_type { };
451 
452  template<typename _Tp, std::size_t _Size>
453  struct is_array<_Tp[_Size]>
454  : public true_type { };
455 
456  template<typename _Tp>
457  struct is_array<_Tp[]>
458  : public true_type { };
459 
460  template<typename>
461  struct __is_pointer_helper
462  : public false_type { };
463 
464  template<typename _Tp>
465  struct __is_pointer_helper<_Tp*>
466  : public true_type { };
467 
468  /// is_pointer
469  template<typename _Tp>
470  struct is_pointer
471  : public __is_pointer_helper<__remove_cv_t<_Tp>>::type
472  { };
473 
474  /// is_lvalue_reference
475  template<typename>
477  : public false_type { };
478 
479  template<typename _Tp>
480  struct is_lvalue_reference<_Tp&>
481  : public true_type { };
482 
483  /// is_rvalue_reference
484  template<typename>
486  : public false_type { };
487 
488  template<typename _Tp>
489  struct is_rvalue_reference<_Tp&&>
490  : public true_type { };
491 
492  template<typename>
493  struct __is_member_object_pointer_helper
494  : public false_type { };
495 
496  template<typename _Tp, typename _Cp>
497  struct __is_member_object_pointer_helper<_Tp _Cp::*>
498  : public __not_<is_function<_Tp>>::type { };
499 
500  /// is_member_object_pointer
501  template<typename _Tp>
503  : public __is_member_object_pointer_helper<__remove_cv_t<_Tp>>::type
504  { };
505 
506  template<typename>
507  struct __is_member_function_pointer_helper
508  : public false_type { };
509 
510  template<typename _Tp, typename _Cp>
511  struct __is_member_function_pointer_helper<_Tp _Cp::*>
512  : public is_function<_Tp>::type { };
513 
514  /// is_member_function_pointer
515  template<typename _Tp>
517  : public __is_member_function_pointer_helper<__remove_cv_t<_Tp>>::type
518  { };
519 
520  /// is_enum
521  template<typename _Tp>
522  struct is_enum
523  : public integral_constant<bool, __is_enum(_Tp)>
524  { };
525 
526  /// is_union
527  template<typename _Tp>
528  struct is_union
529  : public integral_constant<bool, __is_union(_Tp)>
530  { };
531 
532  /// is_class
533  template<typename _Tp>
534  struct is_class
535  : public integral_constant<bool, __is_class(_Tp)>
536  { };
537 
538  /// is_function
539  template<typename _Tp>
540  struct is_function
541  : public __bool_constant<!is_const<const _Tp>::value> { };
542 
543  template<typename _Tp>
544  struct is_function<_Tp&>
545  : public false_type { };
546 
547  template<typename _Tp>
548  struct is_function<_Tp&&>
549  : public false_type { };
550 
551 #define __cpp_lib_is_null_pointer 201309L
552 
553  template<typename>
554  struct __is_null_pointer_helper
555  : public false_type { };
556 
557  template<>
558  struct __is_null_pointer_helper<std::nullptr_t>
559  : public true_type { };
560 
561  /// is_null_pointer (LWG 2247).
562  template<typename _Tp>
564  : public __is_null_pointer_helper<__remove_cv_t<_Tp>>::type
565  { };
566 
567  /// __is_nullptr_t (deprecated extension).
568  /// @deprecated Non-standard. Use `is_null_pointer` instead.
569  template<typename _Tp>
571  : public is_null_pointer<_Tp>
572  { } _GLIBCXX_DEPRECATED_SUGGEST("std::is_null_pointer");
573 
574  // Composite type categories.
575 
576  /// is_reference
577  template<typename _Tp>
579  : public __or_<is_lvalue_reference<_Tp>,
580  is_rvalue_reference<_Tp>>::type
581  { };
582 
583  /// is_arithmetic
584  template<typename _Tp>
586  : public __or_<is_integral<_Tp>, is_floating_point<_Tp>>::type
587  { };
588 
589  /// is_fundamental
590  template<typename _Tp>
592  : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
593  is_null_pointer<_Tp>>::type
594  { };
595 
596  /// is_object
597  template<typename _Tp>
598  struct is_object
599  : public __not_<__or_<is_function<_Tp>, is_reference<_Tp>,
600  is_void<_Tp>>>::type
601  { };
602 
603  template<typename>
604  struct is_member_pointer;
605 
606  /// is_scalar
607  template<typename _Tp>
608  struct is_scalar
609  : public __or_<is_arithmetic<_Tp>, is_enum<_Tp>, is_pointer<_Tp>,
610  is_member_pointer<_Tp>, is_null_pointer<_Tp>>::type
611  { };
612 
613  /// is_compound
614  template<typename _Tp>
615  struct is_compound
616  : public __not_<is_fundamental<_Tp>>::type { };
617 
618  /// @cond undocumented
619  template<typename _Tp>
620  struct __is_member_pointer_helper
621  : public false_type { };
622 
623  template<typename _Tp, typename _Cp>
624  struct __is_member_pointer_helper<_Tp _Cp::*>
625  : public true_type { };
626  /// @endcond
627 
628  /// is_member_pointer
629  template<typename _Tp>
631  : public __is_member_pointer_helper<__remove_cv_t<_Tp>>::type
632  { };
633 
634  template<typename, typename>
635  struct is_same;
636 
637  /// @cond undocumented
638  template<typename _Tp, typename... _Types>
639  using __is_one_of = __or_<is_same<_Tp, _Types>...>;
640 
641  // Check if a type is one of the signed integer types.
642  __extension__
643  template<typename _Tp>
644  using __is_signed_integer = __is_one_of<__remove_cv_t<_Tp>,
645  signed char, signed short, signed int, signed long,
646  signed long long
647 #if defined(__GLIBCXX_TYPE_INT_N_0)
648  , signed __GLIBCXX_TYPE_INT_N_0
649 #endif
650 #if defined(__GLIBCXX_TYPE_INT_N_1)
651  , signed __GLIBCXX_TYPE_INT_N_1
652 #endif
653 #if defined(__GLIBCXX_TYPE_INT_N_2)
654  , signed __GLIBCXX_TYPE_INT_N_2
655 #endif
656 #if defined(__GLIBCXX_TYPE_INT_N_3)
657  , signed __GLIBCXX_TYPE_INT_N_3
658 #endif
659  >;
660 
661  // Check if a type is one of the unsigned integer types.
662  __extension__
663  template<typename _Tp>
664  using __is_unsigned_integer = __is_one_of<__remove_cv_t<_Tp>,
665  unsigned char, unsigned short, unsigned int, unsigned long,
666  unsigned long long
667 #if defined(__GLIBCXX_TYPE_INT_N_0)
668  , unsigned __GLIBCXX_TYPE_INT_N_0
669 #endif
670 #if defined(__GLIBCXX_TYPE_INT_N_1)
671  , unsigned __GLIBCXX_TYPE_INT_N_1
672 #endif
673 #if defined(__GLIBCXX_TYPE_INT_N_2)
674  , unsigned __GLIBCXX_TYPE_INT_N_2
675 #endif
676 #if defined(__GLIBCXX_TYPE_INT_N_3)
677  , unsigned __GLIBCXX_TYPE_INT_N_3
678 #endif
679  >;
680 
681  // Check if a type is one of the signed or unsigned integer types.
682  template<typename _Tp>
683  using __is_standard_integer
684  = __or_<__is_signed_integer<_Tp>, __is_unsigned_integer<_Tp>>;
685 
686  // __void_t (std::void_t for C++11)
687  template<typename...> using __void_t = void;
688 
689  // Utility to detect referenceable types ([defns.referenceable]).
690 
691  template<typename _Tp, typename = void>
692  struct __is_referenceable
693  : public false_type
694  { };
695 
696  template<typename _Tp>
697  struct __is_referenceable<_Tp, __void_t<_Tp&>>
698  : public true_type
699  { };
700  /// @endcond
701 
702  // Type properties.
703 
704  /// is_const
705  template<typename>
706  struct is_const
707  : public false_type { };
708 
709  template<typename _Tp>
710  struct is_const<_Tp const>
711  : public true_type { };
712 
713  /// is_volatile
714  template<typename>
715  struct is_volatile
716  : public false_type { };
717 
718  template<typename _Tp>
719  struct is_volatile<_Tp volatile>
720  : public true_type { };
721 
722  /// is_trivial
723  template<typename _Tp>
724  struct is_trivial
725  : public integral_constant<bool, __is_trivial(_Tp)>
726  {
727  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
728  "template argument must be a complete class or an unbounded array");
729  };
730 
731  /// is_trivially_copyable
732  template<typename _Tp>
734  : public integral_constant<bool, __is_trivially_copyable(_Tp)>
735  {
736  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
737  "template argument must be a complete class or an unbounded array");
738  };
739 
740  /// is_standard_layout
741  template<typename _Tp>
743  : public integral_constant<bool, __is_standard_layout(_Tp)>
744  {
745  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
746  "template argument must be a complete class or an unbounded array");
747  };
748 
749  /** is_pod
750  * @deprecated Deprecated in C++20.
751  * Use `is_standard_layout && is_trivial` instead.
752  */
753  // Could use is_standard_layout && is_trivial instead of the builtin.
754  template<typename _Tp>
755  struct
756  _GLIBCXX20_DEPRECATED("use is_standard_layout && is_trivial instead")
757  is_pod
758  : public integral_constant<bool, __is_pod(_Tp)>
759  {
760  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
761  "template argument must be a complete class or an unbounded array");
762  };
763 
764  /** is_literal_type
765  * @deprecated Deprecated in C++17, removed in C++20.
766  * The idea of a literal type isn't useful.
767  */
768  template<typename _Tp>
769  struct
770  _GLIBCXX17_DEPRECATED
772  : public integral_constant<bool, __is_literal_type(_Tp)>
773  {
774  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
775  "template argument must be a complete class or an unbounded array");
776  };
777 
778  /// is_empty
779  template<typename _Tp>
780  struct is_empty
781  : public integral_constant<bool, __is_empty(_Tp)>
782  { };
783 
784  /// is_polymorphic
785  template<typename _Tp>
787  : public integral_constant<bool, __is_polymorphic(_Tp)>
788  { };
789 
790 #if __cplusplus >= 201402L
791 #define __cpp_lib_is_final 201402L
792  /// is_final
793  /// @since C++14
794  template<typename _Tp>
795  struct is_final
796  : public integral_constant<bool, __is_final(_Tp)>
797  { };
798 #endif
799 
800  /// is_abstract
801  template<typename _Tp>
802  struct is_abstract
803  : public integral_constant<bool, __is_abstract(_Tp)>
804  { };
805 
806  /// @cond undocumented
807  template<typename _Tp,
809  struct __is_signed_helper
810  : public false_type { };
811 
812  template<typename _Tp>
813  struct __is_signed_helper<_Tp, true>
814  : public integral_constant<bool, _Tp(-1) < _Tp(0)>
815  { };
816  /// @endcond
817 
818  /// is_signed
819  template<typename _Tp>
820  struct is_signed
821  : public __is_signed_helper<_Tp>::type
822  { };
823 
824  /// is_unsigned
825  template<typename _Tp>
826  struct is_unsigned
827  : public __and_<is_arithmetic<_Tp>, __not_<is_signed<_Tp>>>
828  { };
829 
830  /// @cond undocumented
831  template<typename _Tp, typename _Up = _Tp&&>
832  _Up
833  __declval(int);
834 
835  template<typename _Tp>
836  _Tp
837  __declval(long);
838  /// @endcond
839 
840  template<typename _Tp>
841  auto declval() noexcept -> decltype(__declval<_Tp>(0));
842 
843  template<typename, unsigned = 0>
844  struct extent;
845 
846  template<typename>
847  struct remove_all_extents;
848 
849  /// @cond undocumented
850  template<typename _Tp>
851  struct __is_array_known_bounds
852  : public integral_constant<bool, (extent<_Tp>::value > 0)>
853  { };
854 
855  template<typename _Tp>
856  struct __is_array_unknown_bounds
857  : public __and_<is_array<_Tp>, __not_<extent<_Tp>>>
858  { };
859 
860  // Destructible and constructible type properties.
861 
862  // In N3290 is_destructible does not say anything about function
863  // types and abstract types, see LWG 2049. This implementation
864  // describes function types as non-destructible and all complete
865  // object types as destructible, iff the explicit destructor
866  // call expression is wellformed.
867  struct __do_is_destructible_impl
868  {
869  template<typename _Tp, typename = decltype(declval<_Tp&>().~_Tp())>
870  static true_type __test(int);
871 
872  template<typename>
873  static false_type __test(...);
874  };
875 
876  template<typename _Tp>
877  struct __is_destructible_impl
878  : public __do_is_destructible_impl
879  {
880  typedef decltype(__test<_Tp>(0)) type;
881  };
882 
883  template<typename _Tp,
884  bool = __or_<is_void<_Tp>,
885  __is_array_unknown_bounds<_Tp>,
886  is_function<_Tp>>::value,
887  bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
888  struct __is_destructible_safe;
889 
890  template<typename _Tp>
891  struct __is_destructible_safe<_Tp, false, false>
892  : public __is_destructible_impl<typename
893  remove_all_extents<_Tp>::type>::type
894  { };
895 
896  template<typename _Tp>
897  struct __is_destructible_safe<_Tp, true, false>
898  : public false_type { };
899 
900  template<typename _Tp>
901  struct __is_destructible_safe<_Tp, false, true>
902  : public true_type { };
903  /// @endcond
904 
905  /// is_destructible
906  template<typename _Tp>
908  : public __is_destructible_safe<_Tp>::type
909  {
910  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
911  "template argument must be a complete class or an unbounded array");
912  };
913 
914  /// @cond undocumented
915 
916  // is_nothrow_destructible requires that is_destructible is
917  // satisfied as well. We realize that by mimicing the
918  // implementation of is_destructible but refer to noexcept(expr)
919  // instead of decltype(expr).
920  struct __do_is_nt_destructible_impl
921  {
922  template<typename _Tp>
923  static __bool_constant<noexcept(declval<_Tp&>().~_Tp())>
924  __test(int);
925 
926  template<typename>
927  static false_type __test(...);
928  };
929 
930  template<typename _Tp>
931  struct __is_nt_destructible_impl
932  : public __do_is_nt_destructible_impl
933  {
934  typedef decltype(__test<_Tp>(0)) type;
935  };
936 
937  template<typename _Tp,
938  bool = __or_<is_void<_Tp>,
939  __is_array_unknown_bounds<_Tp>,
940  is_function<_Tp>>::value,
941  bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
942  struct __is_nt_destructible_safe;
943 
944  template<typename _Tp>
945  struct __is_nt_destructible_safe<_Tp, false, false>
946  : public __is_nt_destructible_impl<typename
947  remove_all_extents<_Tp>::type>::type
948  { };
949 
950  template<typename _Tp>
951  struct __is_nt_destructible_safe<_Tp, true, false>
952  : public false_type { };
953 
954  template<typename _Tp>
955  struct __is_nt_destructible_safe<_Tp, false, true>
956  : public true_type { };
957  /// @endcond
958 
959  /// is_nothrow_destructible
960  template<typename _Tp>
962  : public __is_nt_destructible_safe<_Tp>::type
963  {
964  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
965  "template argument must be a complete class or an unbounded array");
966  };
967 
968  /// @cond undocumented
969  template<typename _Tp, typename... _Args>
970  struct __is_constructible_impl
971  : public __bool_constant<__is_constructible(_Tp, _Args...)>
972  { };
973  /// @endcond
974 
975  /// is_constructible
976  template<typename _Tp, typename... _Args>
978  : public __is_constructible_impl<_Tp, _Args...>
979  {
980  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
981  "template argument must be a complete class or an unbounded array");
982  };
983 
984  /// is_default_constructible
985  template<typename _Tp>
987  : public __is_constructible_impl<_Tp>::type
988  {
989  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
990  "template argument must be a complete class or an unbounded array");
991  };
992 
993  /// @cond undocumented
994  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
995  struct __is_copy_constructible_impl;
996 
997  template<typename _Tp>
998  struct __is_copy_constructible_impl<_Tp, false>
999  : public false_type { };
1000 
1001  template<typename _Tp>
1002  struct __is_copy_constructible_impl<_Tp, true>
1003  : public __is_constructible_impl<_Tp, const _Tp&>
1004  { };
1005  /// @endcond
1006 
1007  /// is_copy_constructible
1008  template<typename _Tp>
1010  : public __is_copy_constructible_impl<_Tp>
1011  {
1012  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1013  "template argument must be a complete class or an unbounded array");
1014  };
1015 
1016  /// @cond undocumented
1017  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1018  struct __is_move_constructible_impl;
1019 
1020  template<typename _Tp>
1021  struct __is_move_constructible_impl<_Tp, false>
1022  : public false_type { };
1023 
1024  template<typename _Tp>
1025  struct __is_move_constructible_impl<_Tp, true>
1026  : public __is_constructible_impl<_Tp, _Tp&&>
1027  { };
1028  /// @endcond
1029 
1030  /// is_move_constructible
1031  template<typename _Tp>
1033  : public __is_move_constructible_impl<_Tp>
1034  {
1035  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1036  "template argument must be a complete class or an unbounded array");
1037  };
1038 
1039  /// @cond undocumented
1040  template<typename _Tp, typename... _Args>
1041  using __is_nothrow_constructible_impl
1042  = __bool_constant<__is_nothrow_constructible(_Tp, _Args...)>;
1043  /// @endcond
1044 
1045  /// is_nothrow_constructible
1046  template<typename _Tp, typename... _Args>
1048  : public __is_nothrow_constructible_impl<_Tp, _Args...>::type
1049  {
1050  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1051  "template argument must be a complete class or an unbounded array");
1052  };
1053 
1054  /// is_nothrow_default_constructible
1055  template<typename _Tp>
1057  : public __bool_constant<__is_nothrow_constructible(_Tp)>
1058  {
1059  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1060  "template argument must be a complete class or an unbounded array");
1061  };
1062 
1063  /// @cond undocumented
1064  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1065  struct __is_nothrow_copy_constructible_impl;
1066 
1067  template<typename _Tp>
1068  struct __is_nothrow_copy_constructible_impl<_Tp, false>
1069  : public false_type { };
1070 
1071  template<typename _Tp>
1072  struct __is_nothrow_copy_constructible_impl<_Tp, true>
1073  : public __is_nothrow_constructible_impl<_Tp, const _Tp&>
1074  { };
1075  /// @endcond
1076 
1077  /// is_nothrow_copy_constructible
1078  template<typename _Tp>
1080  : public __is_nothrow_copy_constructible_impl<_Tp>::type
1081  {
1082  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1083  "template argument must be a complete class or an unbounded array");
1084  };
1085 
1086  /// @cond undocumented
1087  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1088  struct __is_nothrow_move_constructible_impl;
1089 
1090  template<typename _Tp>
1091  struct __is_nothrow_move_constructible_impl<_Tp, false>
1092  : public false_type { };
1093 
1094  template<typename _Tp>
1095  struct __is_nothrow_move_constructible_impl<_Tp, true>
1096  : public __is_nothrow_constructible_impl<_Tp, _Tp&&>
1097  { };
1098  /// @endcond
1099 
1100  /// is_nothrow_move_constructible
1101  template<typename _Tp>
1103  : public __is_nothrow_move_constructible_impl<_Tp>::type
1104  {
1105  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1106  "template argument must be a complete class or an unbounded array");
1107  };
1108 
1109  /// is_assignable
1110  template<typename _Tp, typename _Up>
1112  : public __bool_constant<__is_assignable(_Tp, _Up)>
1113  {
1114  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1115  "template argument must be a complete class or an unbounded array");
1116  };
1117 
1118  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1119  struct __is_copy_assignable_impl;
1120 
1121  template<typename _Tp>
1122  struct __is_copy_assignable_impl<_Tp, false>
1123  : public false_type { };
1124 
1125  template<typename _Tp>
1126  struct __is_copy_assignable_impl<_Tp, true>
1127  : public __bool_constant<__is_assignable(_Tp&, const _Tp&)>
1128  { };
1129 
1130  /// is_copy_assignable
1131  template<typename _Tp>
1133  : public __is_copy_assignable_impl<_Tp>::type
1134  {
1135  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1136  "template argument must be a complete class or an unbounded array");
1137  };
1138 
1139  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1140  struct __is_move_assignable_impl;
1141 
1142  template<typename _Tp>
1143  struct __is_move_assignable_impl<_Tp, false>
1144  : public false_type { };
1145 
1146  template<typename _Tp>
1147  struct __is_move_assignable_impl<_Tp, true>
1148  : public __bool_constant<__is_assignable(_Tp&, _Tp&&)>
1149  { };
1150 
1151  /// is_move_assignable
1152  template<typename _Tp>
1154  : public __is_move_assignable_impl<_Tp>::type
1155  {
1156  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1157  "template argument must be a complete class or an unbounded array");
1158  };
1159 
1160  template<typename _Tp, typename _Up>
1161  using __is_nothrow_assignable_impl
1162  = __bool_constant<__is_nothrow_assignable(_Tp, _Up)>;
1163 
1164  /// is_nothrow_assignable
1165  template<typename _Tp, typename _Up>
1167  : public __is_nothrow_assignable_impl<_Tp, _Up>
1168  {
1169  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1170  "template argument must be a complete class or an unbounded array");
1171  };
1172 
1173  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1174  struct __is_nt_copy_assignable_impl;
1175 
1176  template<typename _Tp>
1177  struct __is_nt_copy_assignable_impl<_Tp, false>
1178  : public false_type { };
1179 
1180  template<typename _Tp>
1181  struct __is_nt_copy_assignable_impl<_Tp, true>
1182  : public __is_nothrow_assignable_impl<_Tp&, const _Tp&>
1183  { };
1184 
1185  /// is_nothrow_copy_assignable
1186  template<typename _Tp>
1188  : public __is_nt_copy_assignable_impl<_Tp>
1189  {
1190  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1191  "template argument must be a complete class or an unbounded array");
1192  };
1193 
1194  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1195  struct __is_nt_move_assignable_impl;
1196 
1197  template<typename _Tp>
1198  struct __is_nt_move_assignable_impl<_Tp, false>
1199  : public false_type { };
1200 
1201  template<typename _Tp>
1202  struct __is_nt_move_assignable_impl<_Tp, true>
1203  : public __is_nothrow_assignable_impl<_Tp&, _Tp&&>
1204  { };
1205 
1206  /// is_nothrow_move_assignable
1207  template<typename _Tp>
1209  : public __is_nt_move_assignable_impl<_Tp>
1210  {
1211  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1212  "template argument must be a complete class or an unbounded array");
1213  };
1214 
1215  /// is_trivially_constructible
1216  template<typename _Tp, typename... _Args>
1218  : public __bool_constant<__is_trivially_constructible(_Tp, _Args...)>
1219  {
1220  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1221  "template argument must be a complete class or an unbounded array");
1222  };
1223 
1224  /// is_trivially_default_constructible
1225  template<typename _Tp>
1227  : public __bool_constant<__is_trivially_constructible(_Tp)>
1228  {
1229  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1230  "template argument must be a complete class or an unbounded array");
1231  };
1232 
1233  struct __do_is_implicitly_default_constructible_impl
1234  {
1235  template <typename _Tp>
1236  static void __helper(const _Tp&);
1237 
1238  template <typename _Tp>
1239  static true_type __test(const _Tp&,
1240  decltype(__helper<const _Tp&>({}))* = 0);
1241 
1242  static false_type __test(...);
1243  };
1244 
1245  template<typename _Tp>
1246  struct __is_implicitly_default_constructible_impl
1247  : public __do_is_implicitly_default_constructible_impl
1248  {
1249  typedef decltype(__test(declval<_Tp>())) type;
1250  };
1251 
1252  template<typename _Tp>
1253  struct __is_implicitly_default_constructible_safe
1254  : public __is_implicitly_default_constructible_impl<_Tp>::type
1255  { };
1256 
1257  template <typename _Tp>
1258  struct __is_implicitly_default_constructible
1259  : public __and_<__is_constructible_impl<_Tp>,
1260  __is_implicitly_default_constructible_safe<_Tp>>
1261  { };
1262 
1263  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1264  struct __is_trivially_copy_constructible_impl;
1265 
1266  template<typename _Tp>
1267  struct __is_trivially_copy_constructible_impl<_Tp, false>
1268  : public false_type { };
1269 
1270  template<typename _Tp>
1271  struct __is_trivially_copy_constructible_impl<_Tp, true>
1272  : public __and_<__is_copy_constructible_impl<_Tp>,
1273  integral_constant<bool,
1274  __is_trivially_constructible(_Tp, const _Tp&)>>
1275  { };
1276 
1277  /// is_trivially_copy_constructible
1278  template<typename _Tp>
1280  : public __is_trivially_copy_constructible_impl<_Tp>
1281  {
1282  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1283  "template argument must be a complete class or an unbounded array");
1284  };
1285 
1286  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1287  struct __is_trivially_move_constructible_impl;
1288 
1289  template<typename _Tp>
1290  struct __is_trivially_move_constructible_impl<_Tp, false>
1291  : public false_type { };
1292 
1293  template<typename _Tp>
1294  struct __is_trivially_move_constructible_impl<_Tp, true>
1295  : public __and_<__is_move_constructible_impl<_Tp>,
1296  integral_constant<bool,
1297  __is_trivially_constructible(_Tp, _Tp&&)>>
1298  { };
1299 
1300  /// is_trivially_move_constructible
1301  template<typename _Tp>
1303  : public __is_trivially_move_constructible_impl<_Tp>
1304  {
1305  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1306  "template argument must be a complete class or an unbounded array");
1307  };
1308 
1309  /// is_trivially_assignable
1310  template<typename _Tp, typename _Up>
1312  : public __bool_constant<__is_trivially_assignable(_Tp, _Up)>
1313  {
1314  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1315  "template argument must be a complete class or an unbounded array");
1316  };
1317 
1318  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1319  struct __is_trivially_copy_assignable_impl;
1320 
1321  template<typename _Tp>
1322  struct __is_trivially_copy_assignable_impl<_Tp, false>
1323  : public false_type { };
1324 
1325  template<typename _Tp>
1326  struct __is_trivially_copy_assignable_impl<_Tp, true>
1327  : public __bool_constant<__is_trivially_assignable(_Tp&, const _Tp&)>
1328  { };
1329 
1330  /// is_trivially_copy_assignable
1331  template<typename _Tp>
1333  : public __is_trivially_copy_assignable_impl<_Tp>
1334  {
1335  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1336  "template argument must be a complete class or an unbounded array");
1337  };
1338 
1339  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1340  struct __is_trivially_move_assignable_impl;
1341 
1342  template<typename _Tp>
1343  struct __is_trivially_move_assignable_impl<_Tp, false>
1344  : public false_type { };
1345 
1346  template<typename _Tp>
1347  struct __is_trivially_move_assignable_impl<_Tp, true>
1348  : public __bool_constant<__is_trivially_assignable(_Tp&, _Tp&&)>
1349  { };
1350 
1351  /// is_trivially_move_assignable
1352  template<typename _Tp>
1354  : public __is_trivially_move_assignable_impl<_Tp>
1355  {
1356  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1357  "template argument must be a complete class or an unbounded array");
1358  };
1359 
1360  /// is_trivially_destructible
1361  template<typename _Tp>
1363  : public __and_<__is_destructible_safe<_Tp>,
1364  __bool_constant<__has_trivial_destructor(_Tp)>>
1365  {
1366  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1367  "template argument must be a complete class or an unbounded array");
1368  };
1369 
1370 
1371  /// has_virtual_destructor
1372  template<typename _Tp>
1374  : public integral_constant<bool, __has_virtual_destructor(_Tp)>
1375  {
1376  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1377  "template argument must be a complete class or an unbounded array");
1378  };
1379 
1380 
1381  // type property queries.
1382 
1383  /// alignment_of
1384  template<typename _Tp>
1386  : public integral_constant<std::size_t, alignof(_Tp)>
1387  {
1388  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1389  "template argument must be a complete class or an unbounded array");
1390  };
1391 
1392  /// rank
1393  template<typename>
1394  struct rank
1395  : public integral_constant<std::size_t, 0> { };
1396 
1397  template<typename _Tp, std::size_t _Size>
1398  struct rank<_Tp[_Size]>
1399  : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1400 
1401  template<typename _Tp>
1402  struct rank<_Tp[]>
1403  : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1404 
1405  /// extent
1406  template<typename, unsigned _Uint>
1407  struct extent
1408  : public integral_constant<std::size_t, 0> { };
1409 
1410  template<typename _Tp, unsigned _Uint, std::size_t _Size>
1411  struct extent<_Tp[_Size], _Uint>
1412  : public integral_constant<std::size_t,
1413  _Uint == 0 ? _Size : extent<_Tp,
1414  _Uint - 1>::value>
1415  { };
1416 
1417  template<typename _Tp, unsigned _Uint>
1418  struct extent<_Tp[], _Uint>
1419  : public integral_constant<std::size_t,
1420  _Uint == 0 ? 0 : extent<_Tp,
1421  _Uint - 1>::value>
1422  { };
1423 
1424 
1425  // Type relations.
1426 
1427  /// is_same
1428  template<typename _Tp, typename _Up>
1429  struct is_same
1430 #ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
1431  : public integral_constant<bool, __is_same(_Tp, _Up)>
1432 #else
1433  : public false_type
1434 #endif
1435  { };
1436 
1437 #ifndef _GLIBCXX_HAVE_BUILTIN_IS_SAME
1438  template<typename _Tp>
1439  struct is_same<_Tp, _Tp>
1440  : public true_type
1441  { };
1442 #endif
1443 
1444  /// is_base_of
1445  template<typename _Base, typename _Derived>
1446  struct is_base_of
1447  : public integral_constant<bool, __is_base_of(_Base, _Derived)>
1448  { };
1449 
1450  template<typename _From, typename _To,
1451  bool = __or_<is_void<_From>, is_function<_To>,
1452  is_array<_To>>::value>
1453  struct __is_convertible_helper
1454  {
1455  typedef typename is_void<_To>::type type;
1456  };
1457 
1458 #pragma GCC diagnostic push
1459 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1460  template<typename _From, typename _To>
1461  class __is_convertible_helper<_From, _To, false>
1462  {
1463  template<typename _To1>
1464  static void __test_aux(_To1) noexcept;
1465 
1466  template<typename _From1, typename _To1,
1467  typename = decltype(__test_aux<_To1>(std::declval<_From1>()))>
1468  static true_type
1469  __test(int);
1470 
1471  template<typename, typename>
1472  static false_type
1473  __test(...);
1474 
1475  public:
1476  typedef decltype(__test<_From, _To>(0)) type;
1477  };
1478 #pragma GCC diagnostic pop
1479 
1480  /// is_convertible
1481  template<typename _From, typename _To>
1483  : public __is_convertible_helper<_From, _To>::type
1484  { };
1485 
1486  // helper trait for unique_ptr<T[]>, shared_ptr<T[]>, and span<T, N>
1487  template<typename _ToElementType, typename _FromElementType>
1489  = is_convertible<_FromElementType(*)[], _ToElementType(*)[]>;
1490 
1491  template<typename _From, typename _To,
1492  bool = __or_<is_void<_From>, is_function<_To>,
1493  is_array<_To>>::value>
1494  struct __is_nt_convertible_helper
1495  : is_void<_To>
1496  { };
1497 
1498 #pragma GCC diagnostic push
1499 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1500  template<typename _From, typename _To>
1501  class __is_nt_convertible_helper<_From, _To, false>
1502  {
1503  template<typename _To1>
1504  static void __test_aux(_To1) noexcept;
1505 
1506  template<typename _From1, typename _To1>
1507  static
1508  __bool_constant<noexcept(__test_aux<_To1>(std::declval<_From1>()))>
1509  __test(int);
1510 
1511  template<typename, typename>
1512  static false_type
1513  __test(...);
1514 
1515  public:
1516  using type = decltype(__test<_From, _To>(0));
1517  };
1518 #pragma GCC diagnostic pop
1519 
1520 #if __cplusplus > 201703L
1521 #define __cpp_lib_is_nothrow_convertible 201806L
1522  /// is_nothrow_convertible
1523  template<typename _From, typename _To>
1525  : public __is_nt_convertible_helper<_From, _To>::type
1526  { };
1527 
1528  /// is_nothrow_convertible_v
1529  template<typename _From, typename _To>
1530  inline constexpr bool is_nothrow_convertible_v
1532 #endif // C++2a
1533 
1534  // Const-volatile modifications.
1535 
1536  /// remove_const
1537  template<typename _Tp>
1539  { typedef _Tp type; };
1540 
1541  template<typename _Tp>
1542  struct remove_const<_Tp const>
1543  { typedef _Tp type; };
1544 
1545  /// remove_volatile
1546  template<typename _Tp>
1548  { typedef _Tp type; };
1549 
1550  template<typename _Tp>
1551  struct remove_volatile<_Tp volatile>
1552  { typedef _Tp type; };
1553 
1554  /// remove_cv
1555  template<typename _Tp>
1556  struct remove_cv
1557  { using type = _Tp; };
1558 
1559  template<typename _Tp>
1560  struct remove_cv<const _Tp>
1561  { using type = _Tp; };
1562 
1563  template<typename _Tp>
1564  struct remove_cv<volatile _Tp>
1565  { using type = _Tp; };
1566 
1567  template<typename _Tp>
1568  struct remove_cv<const volatile _Tp>
1569  { using type = _Tp; };
1570 
1571  /// add_const
1572  template<typename _Tp>
1573  struct add_const
1574  { typedef _Tp const type; };
1575 
1576  /// add_volatile
1577  template<typename _Tp>
1579  { typedef _Tp volatile type; };
1580 
1581  /// add_cv
1582  template<typename _Tp>
1583  struct add_cv
1584  {
1585  typedef typename
1587  };
1588 
1589 #if __cplusplus > 201103L
1590 
1591 #define __cpp_lib_transformation_trait_aliases 201304L
1592 
1593  /// Alias template for remove_const
1594  template<typename _Tp>
1595  using remove_const_t = typename remove_const<_Tp>::type;
1596 
1597  /// Alias template for remove_volatile
1598  template<typename _Tp>
1599  using remove_volatile_t = typename remove_volatile<_Tp>::type;
1600 
1601  /// Alias template for remove_cv
1602  template<typename _Tp>
1603  using remove_cv_t = typename remove_cv<_Tp>::type;
1604 
1605  /// Alias template for add_const
1606  template<typename _Tp>
1607  using add_const_t = typename add_const<_Tp>::type;
1608 
1609  /// Alias template for add_volatile
1610  template<typename _Tp>
1611  using add_volatile_t = typename add_volatile<_Tp>::type;
1612 
1613  /// Alias template for add_cv
1614  template<typename _Tp>
1615  using add_cv_t = typename add_cv<_Tp>::type;
1616 #endif
1617 
1618  // Reference transformations.
1619 
1620  /// remove_reference
1621  template<typename _Tp>
1623  { typedef _Tp type; };
1624 
1625  template<typename _Tp>
1626  struct remove_reference<_Tp&>
1627  { typedef _Tp type; };
1628 
1629  template<typename _Tp>
1630  struct remove_reference<_Tp&&>
1631  { typedef _Tp type; };
1632 
1633  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1634  struct __add_lvalue_reference_helper
1635  { typedef _Tp type; };
1636 
1637  template<typename _Tp>
1638  struct __add_lvalue_reference_helper<_Tp, true>
1639  { typedef _Tp& type; };
1640 
1641  /// add_lvalue_reference
1642  template<typename _Tp>
1644  : public __add_lvalue_reference_helper<_Tp>
1645  { };
1646 
1647  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
1648  struct __add_rvalue_reference_helper
1649  { typedef _Tp type; };
1650 
1651  template<typename _Tp>
1652  struct __add_rvalue_reference_helper<_Tp, true>
1653  { typedef _Tp&& type; };
1654 
1655  /// add_rvalue_reference
1656  template<typename _Tp>
1658  : public __add_rvalue_reference_helper<_Tp>
1659  { };
1660 
1661 #if __cplusplus > 201103L
1662  /// Alias template for remove_reference
1663  template<typename _Tp>
1664  using remove_reference_t = typename remove_reference<_Tp>::type;
1665 
1666  /// Alias template for add_lvalue_reference
1667  template<typename _Tp>
1668  using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1669 
1670  /// Alias template for add_rvalue_reference
1671  template<typename _Tp>
1672  using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1673 #endif
1674 
1675  // Sign modifications.
1676 
1677  /// @cond undocumented
1678 
1679  // Utility for constructing identically cv-qualified types.
1680  template<typename _Unqualified, bool _IsConst, bool _IsVol>
1681  struct __cv_selector;
1682 
1683  template<typename _Unqualified>
1684  struct __cv_selector<_Unqualified, false, false>
1685  { typedef _Unqualified __type; };
1686 
1687  template<typename _Unqualified>
1688  struct __cv_selector<_Unqualified, false, true>
1689  { typedef volatile _Unqualified __type; };
1690 
1691  template<typename _Unqualified>
1692  struct __cv_selector<_Unqualified, true, false>
1693  { typedef const _Unqualified __type; };
1694 
1695  template<typename _Unqualified>
1696  struct __cv_selector<_Unqualified, true, true>
1697  { typedef const volatile _Unqualified __type; };
1698 
1699  template<typename _Qualified, typename _Unqualified,
1700  bool _IsConst = is_const<_Qualified>::value,
1701  bool _IsVol = is_volatile<_Qualified>::value>
1702  class __match_cv_qualifiers
1703  {
1704  typedef __cv_selector<_Unqualified, _IsConst, _IsVol> __match;
1705 
1706  public:
1707  typedef typename __match::__type __type;
1708  };
1709 
1710  // Utility for finding the unsigned versions of signed integral types.
1711  template<typename _Tp>
1712  struct __make_unsigned
1713  { typedef _Tp __type; };
1714 
1715  template<>
1716  struct __make_unsigned<char>
1717  { typedef unsigned char __type; };
1718 
1719  template<>
1720  struct __make_unsigned<signed char>
1721  { typedef unsigned char __type; };
1722 
1723  template<>
1724  struct __make_unsigned<short>
1725  { typedef unsigned short __type; };
1726 
1727  template<>
1728  struct __make_unsigned<int>
1729  { typedef unsigned int __type; };
1730 
1731  template<>
1732  struct __make_unsigned<long>
1733  { typedef unsigned long __type; };
1734 
1735  template<>
1736  struct __make_unsigned<long long>
1737  { typedef unsigned long long __type; };
1738 
1739 #if defined(__GLIBCXX_TYPE_INT_N_0)
1740  __extension__
1741  template<>
1742  struct __make_unsigned<__GLIBCXX_TYPE_INT_N_0>
1743  { typedef unsigned __GLIBCXX_TYPE_INT_N_0 __type; };
1744 #endif
1745 #if defined(__GLIBCXX_TYPE_INT_N_1)
1746  __extension__
1747  template<>
1748  struct __make_unsigned<__GLIBCXX_TYPE_INT_N_1>
1749  { typedef unsigned __GLIBCXX_TYPE_INT_N_1 __type; };
1750 #endif
1751 #if defined(__GLIBCXX_TYPE_INT_N_2)
1752  __extension__
1753  template<>
1754  struct __make_unsigned<__GLIBCXX_TYPE_INT_N_2>
1755  { typedef unsigned __GLIBCXX_TYPE_INT_N_2 __type; };
1756 #endif
1757 #if defined(__GLIBCXX_TYPE_INT_N_3)
1758  __extension__
1759  template<>
1760  struct __make_unsigned<__GLIBCXX_TYPE_INT_N_3>
1761  { typedef unsigned __GLIBCXX_TYPE_INT_N_3 __type; };
1762 #endif
1763 
1764  // Select between integral and enum: not possible to be both.
1765  template<typename _Tp,
1766  bool _IsInt = is_integral<_Tp>::value,
1767  bool _IsEnum = is_enum<_Tp>::value>
1768  class __make_unsigned_selector;
1769 
1770  template<typename _Tp>
1771  class __make_unsigned_selector<_Tp, true, false>
1772  {
1773  using __unsigned_type
1774  = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
1775 
1776  public:
1777  using __type
1778  = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1779  };
1780 
1781  class __make_unsigned_selector_base
1782  {
1783  protected:
1784  template<typename...> struct _List { };
1785 
1786  template<typename _Tp, typename... _Up>
1787  struct _List<_Tp, _Up...> : _List<_Up...>
1788  { static constexpr size_t __size = sizeof(_Tp); };
1789 
1790  template<size_t _Sz, typename _Tp, bool = (_Sz <= _Tp::__size)>
1791  struct __select;
1792 
1793  template<size_t _Sz, typename _Uint, typename... _UInts>
1794  struct __select<_Sz, _List<_Uint, _UInts...>, true>
1795  { using __type = _Uint; };
1796 
1797  template<size_t _Sz, typename _Uint, typename... _UInts>
1798  struct __select<_Sz, _List<_Uint, _UInts...>, false>
1799  : __select<_Sz, _List<_UInts...>>
1800  { };
1801  };
1802 
1803  // Choose unsigned integer type with the smallest rank and same size as _Tp
1804  template<typename _Tp>
1805  class __make_unsigned_selector<_Tp, false, true>
1806  : __make_unsigned_selector_base
1807  {
1808  // With -fshort-enums, an enum may be as small as a char.
1809  using _UInts = _List<unsigned char, unsigned short, unsigned int,
1810  unsigned long, unsigned long long>;
1811 
1812  using __unsigned_type = typename __select<sizeof(_Tp), _UInts>::__type;
1813 
1814  public:
1815  using __type
1816  = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1817  };
1818 
1819  // wchar_t, char8_t, char16_t and char32_t are integral types but are
1820  // neither signed integer types nor unsigned integer types, so must be
1821  // transformed to the unsigned integer type with the smallest rank.
1822  // Use the partial specialization for enumeration types to do that.
1823  template<>
1824  struct __make_unsigned<wchar_t>
1825  {
1826  using __type
1827  = typename __make_unsigned_selector<wchar_t, false, true>::__type;
1828  };
1829 
1830 #ifdef _GLIBCXX_USE_CHAR8_T
1831  template<>
1832  struct __make_unsigned<char8_t>
1833  {
1834  using __type
1835  = typename __make_unsigned_selector<char8_t, false, true>::__type;
1836  };
1837 #endif
1838 
1839  template<>
1840  struct __make_unsigned<char16_t>
1841  {
1842  using __type
1843  = typename __make_unsigned_selector<char16_t, false, true>::__type;
1844  };
1845 
1846  template<>
1847  struct __make_unsigned<char32_t>
1848  {
1849  using __type
1850  = typename __make_unsigned_selector<char32_t, false, true>::__type;
1851  };
1852  /// @endcond
1853 
1854  // Given an integral/enum type, return the corresponding unsigned
1855  // integer type.
1856  // Primary template.
1857  /// make_unsigned
1858  template<typename _Tp>
1860  { typedef typename __make_unsigned_selector<_Tp>::__type type; };
1861 
1862  // Integral, but don't define.
1863  template<>
1864  struct make_unsigned<bool>;
1865 
1866  /// @cond undocumented
1867 
1868  // Utility for finding the signed versions of unsigned integral types.
1869  template<typename _Tp>
1870  struct __make_signed
1871  { typedef _Tp __type; };
1872 
1873  template<>
1874  struct __make_signed<char>
1875  { typedef signed char __type; };
1876 
1877  template<>
1878  struct __make_signed<unsigned char>
1879  { typedef signed char __type; };
1880 
1881  template<>
1882  struct __make_signed<unsigned short>
1883  { typedef signed short __type; };
1884 
1885  template<>
1886  struct __make_signed<unsigned int>
1887  { typedef signed int __type; };
1888 
1889  template<>
1890  struct __make_signed<unsigned long>
1891  { typedef signed long __type; };
1892 
1893  template<>
1894  struct __make_signed<unsigned long long>
1895  { typedef signed long long __type; };
1896 
1897 #if defined(__GLIBCXX_TYPE_INT_N_0)
1898  __extension__
1899  template<>
1900  struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_0>
1901  { typedef __GLIBCXX_TYPE_INT_N_0 __type; };
1902 #endif
1903 #if defined(__GLIBCXX_TYPE_INT_N_1)
1904  __extension__
1905  template<>
1906  struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_1>
1907  { typedef __GLIBCXX_TYPE_INT_N_1 __type; };
1908 #endif
1909 #if defined(__GLIBCXX_TYPE_INT_N_2)
1910  __extension__
1911  template<>
1912  struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_2>
1913  { typedef __GLIBCXX_TYPE_INT_N_2 __type; };
1914 #endif
1915 #if defined(__GLIBCXX_TYPE_INT_N_3)
1916  __extension__
1917  template<>
1918  struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_3>
1919  { typedef __GLIBCXX_TYPE_INT_N_3 __type; };
1920 #endif
1921 
1922  // Select between integral and enum: not possible to be both.
1923  template<typename _Tp,
1924  bool _IsInt = is_integral<_Tp>::value,
1925  bool _IsEnum = is_enum<_Tp>::value>
1926  class __make_signed_selector;
1927 
1928  template<typename _Tp>
1929  class __make_signed_selector<_Tp, true, false>
1930  {
1931  using __signed_type
1932  = typename __make_signed<__remove_cv_t<_Tp>>::__type;
1933 
1934  public:
1935  using __type
1936  = typename __match_cv_qualifiers<_Tp, __signed_type>::__type;
1937  };
1938 
1939  // Choose signed integer type with the smallest rank and same size as _Tp
1940  template<typename _Tp>
1941  class __make_signed_selector<_Tp, false, true>
1942  {
1943  typedef typename __make_unsigned_selector<_Tp>::__type __unsigned_type;
1944 
1945  public:
1946  typedef typename __make_signed_selector<__unsigned_type>::__type __type;
1947  };
1948 
1949  // wchar_t, char16_t and char32_t are integral types but are neither
1950  // signed integer types nor unsigned integer types, so must be
1951  // transformed to the signed integer type with the smallest rank.
1952  // Use the partial specialization for enumeration types to do that.
1953  template<>
1954  struct __make_signed<wchar_t>
1955  {
1956  using __type
1957  = typename __make_signed_selector<wchar_t, false, true>::__type;
1958  };
1959 
1960 #if defined(_GLIBCXX_USE_CHAR8_T)
1961  template<>
1962  struct __make_signed<char8_t>
1963  {
1964  using __type
1965  = typename __make_signed_selector<char8_t, false, true>::__type;
1966  };
1967 #endif
1968 
1969  template<>
1970  struct __make_signed<char16_t>
1971  {
1972  using __type
1973  = typename __make_signed_selector<char16_t, false, true>::__type;
1974  };
1975 
1976  template<>
1977  struct __make_signed<char32_t>
1978  {
1979  using __type
1980  = typename __make_signed_selector<char32_t, false, true>::__type;
1981  };
1982  /// @endcond
1983 
1984  // Given an integral/enum type, return the corresponding signed
1985  // integer type.
1986  // Primary template.
1987  /// make_signed
1988  template<typename _Tp>
1990  { typedef typename __make_signed_selector<_Tp>::__type type; };
1991 
1992  // Integral, but don't define.
1993  template<>
1994  struct make_signed<bool>;
1995 
1996 #if __cplusplus > 201103L
1997  /// Alias template for make_signed
1998  template<typename _Tp>
1999  using make_signed_t = typename make_signed<_Tp>::type;
2000 
2001  /// Alias template for make_unsigned
2002  template<typename _Tp>
2003  using make_unsigned_t = typename make_unsigned<_Tp>::type;
2004 #endif
2005 
2006  // Array modifications.
2007 
2008  /// remove_extent
2009  template<typename _Tp>
2011  { typedef _Tp type; };
2012 
2013  template<typename _Tp, std::size_t _Size>
2014  struct remove_extent<_Tp[_Size]>
2015  { typedef _Tp type; };
2016 
2017  template<typename _Tp>
2018  struct remove_extent<_Tp[]>
2019  { typedef _Tp type; };
2020 
2021  /// remove_all_extents
2022  template<typename _Tp>
2024  { typedef _Tp type; };
2025 
2026  template<typename _Tp, std::size_t _Size>
2027  struct remove_all_extents<_Tp[_Size]>
2028  { typedef typename remove_all_extents<_Tp>::type type; };
2029 
2030  template<typename _Tp>
2031  struct remove_all_extents<_Tp[]>
2032  { typedef typename remove_all_extents<_Tp>::type type; };
2033 
2034 #if __cplusplus > 201103L
2035  /// Alias template for remove_extent
2036  template<typename _Tp>
2037  using remove_extent_t = typename remove_extent<_Tp>::type;
2038 
2039  /// Alias template for remove_all_extents
2040  template<typename _Tp>
2041  using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
2042 #endif
2043 
2044  // Pointer modifications.
2045 
2046  template<typename _Tp, typename>
2047  struct __remove_pointer_helper
2048  { typedef _Tp type; };
2049 
2050  template<typename _Tp, typename _Up>
2051  struct __remove_pointer_helper<_Tp, _Up*>
2052  { typedef _Up type; };
2053 
2054  /// remove_pointer
2055  template<typename _Tp>
2057  : public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
2058  { };
2059 
2060  template<typename _Tp, bool = __or_<__is_referenceable<_Tp>,
2061  is_void<_Tp>>::value>
2062  struct __add_pointer_helper
2063  { typedef _Tp type; };
2064 
2065  template<typename _Tp>
2066  struct __add_pointer_helper<_Tp, true>
2067  { typedef typename remove_reference<_Tp>::type* type; };
2068 
2069  /// add_pointer
2070  template<typename _Tp>
2072  : public __add_pointer_helper<_Tp>
2073  { };
2074 
2075 #if __cplusplus > 201103L
2076  /// Alias template for remove_pointer
2077  template<typename _Tp>
2078  using remove_pointer_t = typename remove_pointer<_Tp>::type;
2079 
2080  /// Alias template for add_pointer
2081  template<typename _Tp>
2082  using add_pointer_t = typename add_pointer<_Tp>::type;
2083 #endif
2084 
2085  template<std::size_t _Len>
2086  struct __aligned_storage_msa
2087  {
2088  union __type
2089  {
2090  unsigned char __data[_Len];
2091  struct __attribute__((__aligned__)) { } __align;
2092  };
2093  };
2094 
2095  /**
2096  * @brief Alignment type.
2097  *
2098  * The value of _Align is a default-alignment which shall be the
2099  * most stringent alignment requirement for any C++ object type
2100  * whose size is no greater than _Len (3.9). The member typedef
2101  * type shall be a POD type suitable for use as uninitialized
2102  * storage for any object whose size is at most _Len and whose
2103  * alignment is a divisor of _Align.
2104  */
2105  template<std::size_t _Len, std::size_t _Align =
2106  __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2108  {
2109  union type
2110  {
2111  unsigned char __data[_Len];
2112  struct __attribute__((__aligned__((_Align)))) { } __align;
2113  };
2114  };
2115 
2116  template <typename... _Types>
2117  struct __strictest_alignment
2118  {
2119  static const size_t _S_alignment = 0;
2120  static const size_t _S_size = 0;
2121  };
2122 
2123  template <typename _Tp, typename... _Types>
2124  struct __strictest_alignment<_Tp, _Types...>
2125  {
2126  static const size_t _S_alignment =
2127  alignof(_Tp) > __strictest_alignment<_Types...>::_S_alignment
2128  ? alignof(_Tp) : __strictest_alignment<_Types...>::_S_alignment;
2129  static const size_t _S_size =
2130  sizeof(_Tp) > __strictest_alignment<_Types...>::_S_size
2131  ? sizeof(_Tp) : __strictest_alignment<_Types...>::_S_size;
2132  };
2133 
2134  /**
2135  * @brief Provide aligned storage for types.
2136  *
2137  * [meta.trans.other]
2138  *
2139  * Provides aligned storage for any of the provided types of at
2140  * least size _Len.
2141  *
2142  * @see aligned_storage
2143  */
2144  template <size_t _Len, typename... _Types>
2146  {
2147  private:
2148  static_assert(sizeof...(_Types) != 0, "At least one type is required");
2149 
2150  using __strictest = __strictest_alignment<_Types...>;
2151  static const size_t _S_len = _Len > __strictest::_S_size
2152  ? _Len : __strictest::_S_size;
2153  public:
2154  /// The value of the strictest alignment of _Types.
2155  static const size_t alignment_value = __strictest::_S_alignment;
2156  /// The storage.
2158  };
2159 
2160  template <size_t _Len, typename... _Types>
2161  const size_t aligned_union<_Len, _Types...>::alignment_value;
2162 
2163  /// @cond undocumented
2164 
2165  // Decay trait for arrays and functions, used for perfect forwarding
2166  // in make_pair, make_tuple, etc.
2167  template<typename _Up,
2168  bool _IsArray = is_array<_Up>::value,
2169  bool _IsFunction = is_function<_Up>::value>
2170  struct __decay_selector;
2171 
2172  // NB: DR 705.
2173  template<typename _Up>
2174  struct __decay_selector<_Up, false, false>
2175  { typedef __remove_cv_t<_Up> __type; };
2176 
2177  template<typename _Up>
2178  struct __decay_selector<_Up, true, false>
2179  { typedef typename remove_extent<_Up>::type* __type; };
2180 
2181  template<typename _Up>
2182  struct __decay_selector<_Up, false, true>
2183  { typedef typename add_pointer<_Up>::type __type; };
2184  /// @endcond
2185 
2186  /// decay
2187  template<typename _Tp>
2188  class decay
2189  {
2190  typedef typename remove_reference<_Tp>::type __remove_type;
2191 
2192  public:
2193  typedef typename __decay_selector<__remove_type>::__type type;
2194  };
2195 
2196  /// @cond undocumented
2197 
2198  // Helper which adds a reference to a type when given a reference_wrapper
2199  template<typename _Tp>
2200  struct __strip_reference_wrapper
2201  {
2202  typedef _Tp __type;
2203  };
2204 
2205  template<typename _Tp>
2206  struct __strip_reference_wrapper<reference_wrapper<_Tp> >
2207  {
2208  typedef _Tp& __type;
2209  };
2210 
2211  // __decay_t (std::decay_t for C++11).
2212  template<typename _Tp>
2213  using __decay_t = typename decay<_Tp>::type;
2214 
2215  template<typename _Tp>
2216  using __decay_and_strip = __strip_reference_wrapper<__decay_t<_Tp>>;
2217  /// @endcond
2218 
2219  // Primary template.
2220  /// Define a member typedef `type` only if a boolean constant is true.
2221  template<bool, typename _Tp = void>
2222  struct enable_if
2223  { };
2224 
2225  // Partial specialization for true.
2226  template<typename _Tp>
2227  struct enable_if<true, _Tp>
2228  { typedef _Tp type; };
2229 
2230  /// @cond undocumented
2231 
2232  // __enable_if_t (std::enable_if_t for C++11)
2233  template<bool _Cond, typename _Tp = void>
2234  using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
2235 
2236  // Helper for SFINAE constraints
2237  template<typename... _Cond>
2238  using _Require = __enable_if_t<__and_<_Cond...>::value>;
2239 
2240  // __remove_cvref_t (std::remove_cvref_t for C++11).
2241  template<typename _Tp>
2242  using __remove_cvref_t
2243  = typename remove_cv<typename remove_reference<_Tp>::type>::type;
2244  /// @endcond
2245 
2246  // Primary template.
2247  /// Define a member typedef @c type to one of two argument types.
2248  template<bool _Cond, typename _Iftrue, typename _Iffalse>
2250  { typedef _Iftrue type; };
2251 
2252  // Partial specialization for false.
2253  template<typename _Iftrue, typename _Iffalse>
2254  struct conditional<false, _Iftrue, _Iffalse>
2255  { typedef _Iffalse type; };
2256 
2257  /// common_type
2258  template<typename... _Tp>
2259  struct common_type;
2260 
2261  // Sfinae-friendly common_type implementation:
2262 
2263  /// @cond undocumented
2264  struct __do_common_type_impl
2265  {
2266  template<typename _Tp, typename _Up>
2267  using __cond_t
2268  = decltype(true ? std::declval<_Tp>() : std::declval<_Up>());
2269 
2270  // if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2271  // denotes a valid type, let C denote that type.
2272  template<typename _Tp, typename _Up>
2273  static __success_type<__decay_t<__cond_t<_Tp, _Up>>>
2274  _S_test(int);
2275 
2276 #if __cplusplus > 201703L
2277  // Otherwise, if COND-RES(CREF(D1), CREF(D2)) denotes a type,
2278  // let C denote the type decay_t<COND-RES(CREF(D1), CREF(D2))>.
2279  template<typename _Tp, typename _Up>
2280  static __success_type<__remove_cvref_t<__cond_t<const _Tp&, const _Up&>>>
2281  _S_test_2(int);
2282 #endif
2283 
2284  template<typename, typename>
2285  static __failure_type
2286  _S_test_2(...);
2287 
2288  template<typename _Tp, typename _Up>
2289  static decltype(_S_test_2<_Tp, _Up>(0))
2290  _S_test(...);
2291  };
2292 
2293  // If sizeof...(T) is zero, there shall be no member type.
2294  template<>
2295  struct common_type<>
2296  { };
2297 
2298  // If sizeof...(T) is one, the same type, if any, as common_type_t<T0, T0>.
2299  template<typename _Tp0>
2300  struct common_type<_Tp0>
2301  : public common_type<_Tp0, _Tp0>
2302  { };
2303 
2304  // If sizeof...(T) is two, ...
2305  template<typename _Tp1, typename _Tp2,
2306  typename _Dp1 = __decay_t<_Tp1>, typename _Dp2 = __decay_t<_Tp2>>
2307  struct __common_type_impl
2308  {
2309  // If is_same_v<T1, D1> is false or is_same_v<T2, D2> is false,
2310  // let C denote the same type, if any, as common_type_t<D1, D2>.
2311  using type = common_type<_Dp1, _Dp2>;
2312  };
2313 
2314  template<typename _Tp1, typename _Tp2>
2315  struct __common_type_impl<_Tp1, _Tp2, _Tp1, _Tp2>
2316  : private __do_common_type_impl
2317  {
2318  // Otherwise, if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2319  // denotes a valid type, let C denote that type.
2320  using type = decltype(_S_test<_Tp1, _Tp2>(0));
2321  };
2322 
2323  // If sizeof...(T) is two, ...
2324  template<typename _Tp1, typename _Tp2>
2325  struct common_type<_Tp1, _Tp2>
2326  : public __common_type_impl<_Tp1, _Tp2>::type
2327  { };
2328 
2329  template<typename...>
2330  struct __common_type_pack
2331  { };
2332 
2333  template<typename, typename, typename = void>
2334  struct __common_type_fold;
2335 
2336  // If sizeof...(T) is greater than two, ...
2337  template<typename _Tp1, typename _Tp2, typename... _Rp>
2338  struct common_type<_Tp1, _Tp2, _Rp...>
2339  : public __common_type_fold<common_type<_Tp1, _Tp2>,
2340  __common_type_pack<_Rp...>>
2341  { };
2342 
2343  // Let C denote the same type, if any, as common_type_t<T1, T2>.
2344  // If there is such a type C, type shall denote the same type, if any,
2345  // as common_type_t<C, R...>.
2346  template<typename _CTp, typename... _Rp>
2347  struct __common_type_fold<_CTp, __common_type_pack<_Rp...>,
2348  __void_t<typename _CTp::type>>
2349  : public common_type<typename _CTp::type, _Rp...>
2350  { };
2351 
2352  // Otherwise, there shall be no member type.
2353  template<typename _CTp, typename _Rp>
2354  struct __common_type_fold<_CTp, _Rp, void>
2355  { };
2356 
2357  template<typename _Tp, bool = is_enum<_Tp>::value>
2358  struct __underlying_type_impl
2359  {
2360  using type = __underlying_type(_Tp);
2361  };
2362 
2363  template<typename _Tp>
2364  struct __underlying_type_impl<_Tp, false>
2365  { };
2366  /// @endcond
2367 
2368  /// The underlying type of an enum.
2369  template<typename _Tp>
2371  : public __underlying_type_impl<_Tp>
2372  { };
2373 
2374  /// @cond undocumented
2375  template<typename _Tp>
2376  struct __declval_protector
2377  {
2378  static const bool __stop = false;
2379  };
2380  /// @endcond
2381 
2382  /** Utility to simplify expressions used in unevaluated operands
2383  * @since C++11
2384  * @ingroup utilities
2385  */
2386  template<typename _Tp>
2387  auto declval() noexcept -> decltype(__declval<_Tp>(0))
2388  {
2389  static_assert(__declval_protector<_Tp>::__stop,
2390  "declval() must not be used!");
2391  return __declval<_Tp>(0);
2392  }
2393 
2394  /// result_of
2395  template<typename _Signature>
2396  struct result_of;
2397 
2398  // Sfinae-friendly result_of implementation:
2399 
2400 #define __cpp_lib_result_of_sfinae 201210L
2401 
2402  /// @cond undocumented
2403  struct __invoke_memfun_ref { };
2404  struct __invoke_memfun_deref { };
2405  struct __invoke_memobj_ref { };
2406  struct __invoke_memobj_deref { };
2407  struct __invoke_other { };
2408 
2409  // Associate a tag type with a specialization of __success_type.
2410  template<typename _Tp, typename _Tag>
2411  struct __result_of_success : __success_type<_Tp>
2412  { using __invoke_type = _Tag; };
2413 
2414  // [func.require] paragraph 1 bullet 1:
2415  struct __result_of_memfun_ref_impl
2416  {
2417  template<typename _Fp, typename _Tp1, typename... _Args>
2418  static __result_of_success<decltype(
2419  (std::declval<_Tp1>().*std::declval<_Fp>())(std::declval<_Args>()...)
2420  ), __invoke_memfun_ref> _S_test(int);
2421 
2422  template<typename...>
2423  static __failure_type _S_test(...);
2424  };
2425 
2426  template<typename _MemPtr, typename _Arg, typename... _Args>
2427  struct __result_of_memfun_ref
2428  : private __result_of_memfun_ref_impl
2429  {
2430  typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2431  };
2432 
2433  // [func.require] paragraph 1 bullet 2:
2434  struct __result_of_memfun_deref_impl
2435  {
2436  template<typename _Fp, typename _Tp1, typename... _Args>
2437  static __result_of_success<decltype(
2438  ((*std::declval<_Tp1>()).*std::declval<_Fp>())(std::declval<_Args>()...)
2439  ), __invoke_memfun_deref> _S_test(int);
2440 
2441  template<typename...>
2442  static __failure_type _S_test(...);
2443  };
2444 
2445  template<typename _MemPtr, typename _Arg, typename... _Args>
2446  struct __result_of_memfun_deref
2447  : private __result_of_memfun_deref_impl
2448  {
2449  typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
2450  };
2451 
2452  // [func.require] paragraph 1 bullet 3:
2453  struct __result_of_memobj_ref_impl
2454  {
2455  template<typename _Fp, typename _Tp1>
2456  static __result_of_success<decltype(
2457  std::declval<_Tp1>().*std::declval<_Fp>()
2458  ), __invoke_memobj_ref> _S_test(int);
2459 
2460  template<typename, typename>
2461  static __failure_type _S_test(...);
2462  };
2463 
2464  template<typename _MemPtr, typename _Arg>
2465  struct __result_of_memobj_ref
2466  : private __result_of_memobj_ref_impl
2467  {
2468  typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2469  };
2470 
2471  // [func.require] paragraph 1 bullet 4:
2472  struct __result_of_memobj_deref_impl
2473  {
2474  template<typename _Fp, typename _Tp1>
2475  static __result_of_success<decltype(
2476  (*std::declval<_Tp1>()).*std::declval<_Fp>()
2477  ), __invoke_memobj_deref> _S_test(int);
2478 
2479  template<typename, typename>
2480  static __failure_type _S_test(...);
2481  };
2482 
2483  template<typename _MemPtr, typename _Arg>
2484  struct __result_of_memobj_deref
2485  : private __result_of_memobj_deref_impl
2486  {
2487  typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
2488  };
2489 
2490  template<typename _MemPtr, typename _Arg>
2491  struct __result_of_memobj;
2492 
2493  template<typename _Res, typename _Class, typename _Arg>
2494  struct __result_of_memobj<_Res _Class::*, _Arg>
2495  {
2496  typedef __remove_cvref_t<_Arg> _Argval;
2497  typedef _Res _Class::* _MemPtr;
2498  typedef typename __conditional_t<__or_<is_same<_Argval, _Class>,
2499  is_base_of<_Class, _Argval>>::value,
2500  __result_of_memobj_ref<_MemPtr, _Arg>,
2501  __result_of_memobj_deref<_MemPtr, _Arg>
2502  >::type type;
2503  };
2504 
2505  template<typename _MemPtr, typename _Arg, typename... _Args>
2506  struct __result_of_memfun;
2507 
2508  template<typename _Res, typename _Class, typename _Arg, typename... _Args>
2509  struct __result_of_memfun<_Res _Class::*, _Arg, _Args...>
2510  {
2511  typedef typename remove_reference<_Arg>::type _Argval;
2512  typedef _Res _Class::* _MemPtr;
2513  typedef typename __conditional_t<is_base_of<_Class, _Argval>::value,
2514  __result_of_memfun_ref<_MemPtr, _Arg, _Args...>,
2515  __result_of_memfun_deref<_MemPtr, _Arg, _Args...>
2516  >::type type;
2517  };
2518 
2519  // _GLIBCXX_RESOLVE_LIB_DEFECTS
2520  // 2219. INVOKE-ing a pointer to member with a reference_wrapper
2521  // as the object expression
2522 
2523  // Used by result_of, invoke etc. to unwrap a reference_wrapper.
2524  template<typename _Tp, typename _Up = __remove_cvref_t<_Tp>>
2525  struct __inv_unwrap
2526  {
2527  using type = _Tp;
2528  };
2529 
2530  template<typename _Tp, typename _Up>
2531  struct __inv_unwrap<_Tp, reference_wrapper<_Up>>
2532  {
2533  using type = _Up&;
2534  };
2535 
2536  template<bool, bool, typename _Functor, typename... _ArgTypes>
2537  struct __result_of_impl
2538  {
2539  typedef __failure_type type;
2540  };
2541 
2542  template<typename _MemPtr, typename _Arg>
2543  struct __result_of_impl<true, false, _MemPtr, _Arg>
2544  : public __result_of_memobj<__decay_t<_MemPtr>,
2545  typename __inv_unwrap<_Arg>::type>
2546  { };
2547 
2548  template<typename _MemPtr, typename _Arg, typename... _Args>
2549  struct __result_of_impl<false, true, _MemPtr, _Arg, _Args...>
2550  : public __result_of_memfun<__decay_t<_MemPtr>,
2551  typename __inv_unwrap<_Arg>::type, _Args...>
2552  { };
2553 
2554  // [func.require] paragraph 1 bullet 5:
2555  struct __result_of_other_impl
2556  {
2557  template<typename _Fn, typename... _Args>
2558  static __result_of_success<decltype(
2559  std::declval<_Fn>()(std::declval<_Args>()...)
2560  ), __invoke_other> _S_test(int);
2561 
2562  template<typename...>
2563  static __failure_type _S_test(...);
2564  };
2565 
2566  template<typename _Functor, typename... _ArgTypes>
2567  struct __result_of_impl<false, false, _Functor, _ArgTypes...>
2568  : private __result_of_other_impl
2569  {
2570  typedef decltype(_S_test<_Functor, _ArgTypes...>(0)) type;
2571  };
2572 
2573  // __invoke_result (std::invoke_result for C++11)
2574  template<typename _Functor, typename... _ArgTypes>
2575  struct __invoke_result
2576  : public __result_of_impl<
2577  is_member_object_pointer<
2578  typename remove_reference<_Functor>::type
2579  >::value,
2580  is_member_function_pointer<
2581  typename remove_reference<_Functor>::type
2582  >::value,
2583  _Functor, _ArgTypes...
2584  >::type
2585  { };
2586  /// @endcond
2587 
2588  template<typename _Functor, typename... _ArgTypes>
2589  struct result_of<_Functor(_ArgTypes...)>
2590  : public __invoke_result<_Functor, _ArgTypes...>
2591  { } _GLIBCXX17_DEPRECATED_SUGGEST("std::invoke_result");
2592 
2593 #if __cplusplus >= 201402L
2594  /// Alias template for aligned_storage
2595  template<size_t _Len, size_t _Align =
2596  __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2598 
2599  template <size_t _Len, typename... _Types>
2600  using aligned_union_t = typename aligned_union<_Len, _Types...>::type;
2601 
2602  /// Alias template for decay
2603  template<typename _Tp>
2604  using decay_t = typename decay<_Tp>::type;
2605 
2606  /// Alias template for enable_if
2607  template<bool _Cond, typename _Tp = void>
2609 
2610  /// Alias template for conditional
2611  template<bool _Cond, typename _Iftrue, typename _Iffalse>
2612  using conditional_t = typename conditional<_Cond, _Iftrue, _Iffalse>::type;
2613 
2614  /// Alias template for common_type
2615  template<typename... _Tp>
2616  using common_type_t = typename common_type<_Tp...>::type;
2617 
2618  /// Alias template for underlying_type
2619  template<typename _Tp>
2621 
2622  /// Alias template for result_of
2623  template<typename _Tp>
2625 #endif // C++14
2626 
2627 #if __cplusplus >= 201703L || !defined(__STRICT_ANSI__) // c++17 or gnu++11
2628 #define __cpp_lib_void_t 201411L
2629  /// A metafunction that always yields void, used for detecting valid types.
2630  template<typename...> using void_t = void;
2631 #endif
2632 
2633  /// @cond undocumented
2634 
2635  /// Implementation of the detection idiom (negative case).
2636  template<typename _Default, typename _AlwaysVoid,
2637  template<typename...> class _Op, typename... _Args>
2638  struct __detector
2639  {
2640  using value_t = false_type;
2641  using type = _Default;
2642  };
2643 
2644  /// Implementation of the detection idiom (positive case).
2645  template<typename _Default, template<typename...> class _Op,
2646  typename... _Args>
2647  struct __detector<_Default, __void_t<_Op<_Args...>>, _Op, _Args...>
2648  {
2649  using value_t = true_type;
2650  using type = _Op<_Args...>;
2651  };
2652 
2653  // Detect whether _Op<_Args...> is a valid type, use _Default if not.
2654  template<typename _Default, template<typename...> class _Op,
2655  typename... _Args>
2656  using __detected_or = __detector<_Default, void, _Op, _Args...>;
2657 
2658  // _Op<_Args...> if that is a valid type, otherwise _Default.
2659  template<typename _Default, template<typename...> class _Op,
2660  typename... _Args>
2661  using __detected_or_t
2662  = typename __detected_or<_Default, _Op, _Args...>::type;
2663 
2664  /**
2665  * Use SFINAE to determine if the type _Tp has a publicly-accessible
2666  * member type _NTYPE.
2667  */
2668 #define _GLIBCXX_HAS_NESTED_TYPE(_NTYPE) \
2669  template<typename _Tp, typename = __void_t<>> \
2670  struct __has_##_NTYPE \
2671  : false_type \
2672  { }; \
2673  template<typename _Tp> \
2674  struct __has_##_NTYPE<_Tp, __void_t<typename _Tp::_NTYPE>> \
2675  : true_type \
2676  { };
2677 
2678  template <typename _Tp>
2679  struct __is_swappable;
2680 
2681  template <typename _Tp>
2682  struct __is_nothrow_swappable;
2683 
2684  template<typename>
2685  struct __is_tuple_like_impl : false_type
2686  { };
2687 
2688  // Internal type trait that allows us to sfinae-protect tuple_cat.
2689  template<typename _Tp>
2690  struct __is_tuple_like
2691  : public __is_tuple_like_impl<__remove_cvref_t<_Tp>>::type
2692  { };
2693  /// @endcond
2694 
2695  template<typename _Tp>
2696  _GLIBCXX20_CONSTEXPR
2697  inline
2698  _Require<__not_<__is_tuple_like<_Tp>>,
2699  is_move_constructible<_Tp>,
2700  is_move_assignable<_Tp>>
2701  swap(_Tp&, _Tp&)
2702  noexcept(__and_<is_nothrow_move_constructible<_Tp>,
2703  is_nothrow_move_assignable<_Tp>>::value);
2704 
2705  template<typename _Tp, size_t _Nm>
2706  _GLIBCXX20_CONSTEXPR
2707  inline
2708  __enable_if_t<__is_swappable<_Tp>::value>
2709  swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
2710  noexcept(__is_nothrow_swappable<_Tp>::value);
2711 
2712  /// @cond undocumented
2713  namespace __swappable_details {
2714  using std::swap;
2715 
2716  struct __do_is_swappable_impl
2717  {
2718  template<typename _Tp, typename
2719  = decltype(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))>
2720  static true_type __test(int);
2721 
2722  template<typename>
2723  static false_type __test(...);
2724  };
2725 
2726  struct __do_is_nothrow_swappable_impl
2727  {
2728  template<typename _Tp>
2729  static __bool_constant<
2730  noexcept(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))
2731  > __test(int);
2732 
2733  template<typename>
2734  static false_type __test(...);
2735  };
2736 
2737  } // namespace __swappable_details
2738 
2739  template<typename _Tp>
2740  struct __is_swappable_impl
2741  : public __swappable_details::__do_is_swappable_impl
2742  {
2743  typedef decltype(__test<_Tp>(0)) type;
2744  };
2745 
2746  template<typename _Tp>
2747  struct __is_nothrow_swappable_impl
2748  : public __swappable_details::__do_is_nothrow_swappable_impl
2749  {
2750  typedef decltype(__test<_Tp>(0)) type;
2751  };
2752 
2753  template<typename _Tp>
2754  struct __is_swappable
2755  : public __is_swappable_impl<_Tp>::type
2756  { };
2757 
2758  template<typename _Tp>
2759  struct __is_nothrow_swappable
2760  : public __is_nothrow_swappable_impl<_Tp>::type
2761  { };
2762  /// @endcond
2763 
2764 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
2765 #define __cpp_lib_is_swappable 201603L
2766  /// Metafunctions used for detecting swappable types: p0185r1
2767 
2768  /// is_swappable
2769  template<typename _Tp>
2771  : public __is_swappable_impl<_Tp>::type
2772  {
2773  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2774  "template argument must be a complete class or an unbounded array");
2775  };
2776 
2777  /// is_nothrow_swappable
2778  template<typename _Tp>
2780  : public __is_nothrow_swappable_impl<_Tp>::type
2781  {
2782  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2783  "template argument must be a complete class or an unbounded array");
2784  };
2785 
2786 #if __cplusplus >= 201402L
2787  /// is_swappable_v
2788  template<typename _Tp>
2789  _GLIBCXX17_INLINE constexpr bool is_swappable_v =
2791 
2792  /// is_nothrow_swappable_v
2793  template<typename _Tp>
2794  _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_v =
2796 #endif // __cplusplus >= 201402L
2797 
2798  /// @cond undocumented
2799  namespace __swappable_with_details {
2800  using std::swap;
2801 
2802  struct __do_is_swappable_with_impl
2803  {
2804  template<typename _Tp, typename _Up, typename
2805  = decltype(swap(std::declval<_Tp>(), std::declval<_Up>())),
2806  typename
2807  = decltype(swap(std::declval<_Up>(), std::declval<_Tp>()))>
2808  static true_type __test(int);
2809 
2810  template<typename, typename>
2811  static false_type __test(...);
2812  };
2813 
2814  struct __do_is_nothrow_swappable_with_impl
2815  {
2816  template<typename _Tp, typename _Up>
2817  static __bool_constant<
2818  noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()))
2819  &&
2820  noexcept(swap(std::declval<_Up>(), std::declval<_Tp>()))
2821  > __test(int);
2822 
2823  template<typename, typename>
2824  static false_type __test(...);
2825  };
2826 
2827  } // namespace __swappable_with_details
2828 
2829  template<typename _Tp, typename _Up>
2830  struct __is_swappable_with_impl
2831  : public __swappable_with_details::__do_is_swappable_with_impl
2832  {
2833  typedef decltype(__test<_Tp, _Up>(0)) type;
2834  };
2835 
2836  // Optimization for the homogenous lvalue case, not required:
2837  template<typename _Tp>
2838  struct __is_swappable_with_impl<_Tp&, _Tp&>
2839  : public __swappable_details::__do_is_swappable_impl
2840  {
2841  typedef decltype(__test<_Tp&>(0)) type;
2842  };
2843 
2844  template<typename _Tp, typename _Up>
2845  struct __is_nothrow_swappable_with_impl
2846  : public __swappable_with_details::__do_is_nothrow_swappable_with_impl
2847  {
2848  typedef decltype(__test<_Tp, _Up>(0)) type;
2849  };
2850 
2851  // Optimization for the homogenous lvalue case, not required:
2852  template<typename _Tp>
2853  struct __is_nothrow_swappable_with_impl<_Tp&, _Tp&>
2854  : public __swappable_details::__do_is_nothrow_swappable_impl
2855  {
2856  typedef decltype(__test<_Tp&>(0)) type;
2857  };
2858  /// @endcond
2859 
2860  /// is_swappable_with
2861  template<typename _Tp, typename _Up>
2863  : public __is_swappable_with_impl<_Tp, _Up>::type
2864  {
2865  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2866  "first template argument must be a complete class or an unbounded array");
2867  static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2868  "second template argument must be a complete class or an unbounded array");
2869  };
2870 
2871  /// is_nothrow_swappable_with
2872  template<typename _Tp, typename _Up>
2874  : public __is_nothrow_swappable_with_impl<_Tp, _Up>::type
2875  {
2876  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2877  "first template argument must be a complete class or an unbounded array");
2878  static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2879  "second template argument must be a complete class or an unbounded array");
2880  };
2881 
2882 #if __cplusplus >= 201402L
2883  /// is_swappable_with_v
2884  template<typename _Tp, typename _Up>
2885  _GLIBCXX17_INLINE constexpr bool is_swappable_with_v =
2887 
2888  /// is_nothrow_swappable_with_v
2889  template<typename _Tp, typename _Up>
2890  _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_with_v =
2892 #endif // __cplusplus >= 201402L
2893 
2894 #endif// c++1z or gnu++11
2895 
2896  /// @cond undocumented
2897 
2898  // __is_invocable (std::is_invocable for C++11)
2899 
2900  // The primary template is used for invalid INVOKE expressions.
2901  template<typename _Result, typename _Ret,
2902  bool = is_void<_Ret>::value, typename = void>
2903  struct __is_invocable_impl
2904  : false_type
2905  {
2906  using __nothrow_type = false_type; // For is_nothrow_invocable_r
2907  };
2908 
2909  // Used for valid INVOKE and INVOKE<void> expressions.
2910  template<typename _Result, typename _Ret>
2911  struct __is_invocable_impl<_Result, _Ret,
2912  /* is_void<_Ret> = */ true,
2913  __void_t<typename _Result::type>>
2914  : true_type
2915  {
2916  using __nothrow_type = true_type; // For is_nothrow_invocable_r
2917  };
2918 
2919 #pragma GCC diagnostic push
2920 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
2921  // Used for INVOKE<R> expressions to check the implicit conversion to R.
2922  template<typename _Result, typename _Ret>
2923  struct __is_invocable_impl<_Result, _Ret,
2924  /* is_void<_Ret> = */ false,
2925  __void_t<typename _Result::type>>
2926  {
2927  private:
2928  // The type of the INVOKE expression.
2929  // Unlike declval, this doesn't add_rvalue_reference, so it respects
2930  // guaranteed copy elision.
2931  static typename _Result::type _S_get() noexcept;
2932 
2933  template<typename _Tp>
2934  static void _S_conv(_Tp) noexcept;
2935 
2936  // This overload is viable if INVOKE(f, args...) can convert to _Tp.
2937  template<typename _Tp, bool _Check_Noex = false,
2938  typename = decltype(_S_conv<_Tp>(_S_get())),
2939  bool _Noex = noexcept(_S_conv<_Tp>(_S_get()))>
2940  static __bool_constant<_Check_Noex ? _Noex : true>
2941  _S_test(int);
2942 
2943  template<typename _Tp, bool = false>
2944  static false_type
2945  _S_test(...);
2946 
2947  public:
2948  // For is_invocable_r
2949  using type = decltype(_S_test<_Ret>(1));
2950 
2951  // For is_nothrow_invocable_r
2952  using __nothrow_type = decltype(_S_test<_Ret, true>(1));
2953  };
2954 #pragma GCC diagnostic pop
2955 
2956  template<typename _Fn, typename... _ArgTypes>
2957  struct __is_invocable
2958  : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
2959  { };
2960 
2961  template<typename _Fn, typename _Tp, typename... _Args>
2962  constexpr bool __call_is_nt(__invoke_memfun_ref)
2963  {
2964  using _Up = typename __inv_unwrap<_Tp>::type;
2965  return noexcept((std::declval<_Up>().*std::declval<_Fn>())(
2966  std::declval<_Args>()...));
2967  }
2968 
2969  template<typename _Fn, typename _Tp, typename... _Args>
2970  constexpr bool __call_is_nt(__invoke_memfun_deref)
2971  {
2972  return noexcept(((*std::declval<_Tp>()).*std::declval<_Fn>())(
2973  std::declval<_Args>()...));
2974  }
2975 
2976  template<typename _Fn, typename _Tp>
2977  constexpr bool __call_is_nt(__invoke_memobj_ref)
2978  {
2979  using _Up = typename __inv_unwrap<_Tp>::type;
2980  return noexcept(std::declval<_Up>().*std::declval<_Fn>());
2981  }
2982 
2983  template<typename _Fn, typename _Tp>
2984  constexpr bool __call_is_nt(__invoke_memobj_deref)
2985  {
2986  return noexcept((*std::declval<_Tp>()).*std::declval<_Fn>());
2987  }
2988 
2989  template<typename _Fn, typename... _Args>
2990  constexpr bool __call_is_nt(__invoke_other)
2991  {
2992  return noexcept(std::declval<_Fn>()(std::declval<_Args>()...));
2993  }
2994 
2995  template<typename _Result, typename _Fn, typename... _Args>
2996  struct __call_is_nothrow
2997  : __bool_constant<
2998  std::__call_is_nt<_Fn, _Args...>(typename _Result::__invoke_type{})
2999  >
3000  { };
3001 
3002  template<typename _Fn, typename... _Args>
3003  using __call_is_nothrow_
3004  = __call_is_nothrow<__invoke_result<_Fn, _Args...>, _Fn, _Args...>;
3005 
3006  // __is_nothrow_invocable (std::is_nothrow_invocable for C++11)
3007  template<typename _Fn, typename... _Args>
3008  struct __is_nothrow_invocable
3009  : __and_<__is_invocable<_Fn, _Args...>,
3010  __call_is_nothrow_<_Fn, _Args...>>::type
3011  { };
3012 
3013 #pragma GCC diagnostic push
3014 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
3015  struct __nonesuchbase {};
3016  struct __nonesuch : private __nonesuchbase {
3017  ~__nonesuch() = delete;
3018  __nonesuch(__nonesuch const&) = delete;
3019  void operator=(__nonesuch const&) = delete;
3020  };
3021 #pragma GCC diagnostic pop
3022  /// @endcond
3023 
3024 #if __cplusplus >= 201703L
3025 # define __cpp_lib_is_invocable 201703L
3026 
3027  /// std::invoke_result
3028  template<typename _Functor, typename... _ArgTypes>
3030  : public __invoke_result<_Functor, _ArgTypes...>
3031  {
3032  static_assert(std::__is_complete_or_unbounded(__type_identity<_Functor>{}),
3033  "_Functor must be a complete class or an unbounded array");
3034  static_assert((std::__is_complete_or_unbounded(
3035  __type_identity<_ArgTypes>{}) && ...),
3036  "each argument type must be a complete class or an unbounded array");
3037  };
3038 
3039  /// std::invoke_result_t
3040  template<typename _Fn, typename... _Args>
3041  using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3042 
3043  /// std::is_invocable
3044  template<typename _Fn, typename... _ArgTypes>
3046  : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
3047  {
3048  static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3049  "_Fn must be a complete class or an unbounded array");
3050  static_assert((std::__is_complete_or_unbounded(
3051  __type_identity<_ArgTypes>{}) && ...),
3052  "each argument type must be a complete class or an unbounded array");
3053  };
3054 
3055  /// std::is_invocable_r
3056  template<typename _Ret, typename _Fn, typename... _ArgTypes>
3058  : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>::type
3059  {
3060  static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3061  "_Fn must be a complete class or an unbounded array");
3062  static_assert((std::__is_complete_or_unbounded(
3063  __type_identity<_ArgTypes>{}) && ...),
3064  "each argument type must be a complete class or an unbounded array");
3065  static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3066  "_Ret must be a complete class or an unbounded array");
3067  };
3068 
3069  /// std::is_nothrow_invocable
3070  template<typename _Fn, typename... _ArgTypes>
3072  : __and_<__is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>,
3073  __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3074  {
3075  static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3076  "_Fn must be a complete class or an unbounded array");
3077  static_assert((std::__is_complete_or_unbounded(
3078  __type_identity<_ArgTypes>{}) && ...),
3079  "each argument type must be a complete class or an unbounded array");
3080  };
3081 
3082  /// @cond undocumented
3083  template<typename _Result, typename _Ret>
3084  using __is_nt_invocable_impl
3085  = typename __is_invocable_impl<_Result, _Ret>::__nothrow_type;
3086  /// @endcond
3087 
3088  /// std::is_nothrow_invocable_r
3089  template<typename _Ret, typename _Fn, typename... _ArgTypes>
3091  : __and_<__is_nt_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>,
3092  __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3093  {
3094  static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3095  "_Fn must be a complete class or an unbounded array");
3096  static_assert((std::__is_complete_or_unbounded(
3097  __type_identity<_ArgTypes>{}) && ...),
3098  "each argument type must be a complete class or an unbounded array");
3099  static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3100  "_Ret must be a complete class or an unbounded array");
3101  };
3102 #endif // C++17
3103 
3104 #if __cplusplus >= 201703L
3105 # define __cpp_lib_type_trait_variable_templates 201510L
3106  /**
3107  * @defgroup variable_templates Variable templates for type traits
3108  * @ingroup metaprogramming
3109  *
3110  * Each variable `is_xxx_v<T>` is a boolean constant with the same value
3111  * as the `value` member of the corresponding type trait `is_xxx<T>`.
3112  *
3113  * @since C++17 unless noted otherwise.
3114  */
3115 
3116  /**
3117  * @{
3118  * @ingroup variable_templates
3119  */
3120 template <typename _Tp>
3121  inline constexpr bool is_void_v = is_void<_Tp>::value;
3122 template <typename _Tp>
3123  inline constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
3124 template <typename _Tp>
3125  inline constexpr bool is_integral_v = is_integral<_Tp>::value;
3126 template <typename _Tp>
3127  inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
3128 template <typename _Tp>
3129  inline constexpr bool is_array_v = is_array<_Tp>::value;
3130 template <typename _Tp>
3131  inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
3132 template <typename _Tp>
3133  inline constexpr bool is_lvalue_reference_v =
3135 template <typename _Tp>
3136  inline constexpr bool is_rvalue_reference_v =
3138 template <typename _Tp>
3139  inline constexpr bool is_member_object_pointer_v =
3141 template <typename _Tp>
3142  inline constexpr bool is_member_function_pointer_v =
3144 template <typename _Tp>
3145  inline constexpr bool is_enum_v = is_enum<_Tp>::value;
3146 template <typename _Tp>
3147  inline constexpr bool is_union_v = is_union<_Tp>::value;
3148 template <typename _Tp>
3149  inline constexpr bool is_class_v = is_class<_Tp>::value;
3150 template <typename _Tp>
3151  inline constexpr bool is_function_v = is_function<_Tp>::value;
3152 template <typename _Tp>
3153  inline constexpr bool is_reference_v = is_reference<_Tp>::value;
3154 template <typename _Tp>
3155  inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
3156 template <typename _Tp>
3157  inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
3158 template <typename _Tp>
3159  inline constexpr bool is_object_v = is_object<_Tp>::value;
3160 template <typename _Tp>
3161  inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
3162 template <typename _Tp>
3163  inline constexpr bool is_compound_v = is_compound<_Tp>::value;
3164 template <typename _Tp>
3165  inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
3166 template <typename _Tp>
3167  inline constexpr bool is_const_v = is_const<_Tp>::value;
3168 template <typename _Tp>
3169  inline constexpr bool is_volatile_v = is_volatile<_Tp>::value;
3170 template <typename _Tp>
3171  inline constexpr bool is_trivial_v = is_trivial<_Tp>::value;
3172 template <typename _Tp>
3173  inline constexpr bool is_trivially_copyable_v =
3175 template <typename _Tp>
3176  inline constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
3177 #pragma GCC diagnostic push
3178 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
3179 template <typename _Tp>
3180  _GLIBCXX20_DEPRECATED("use is_standard_layout_v && is_trivial_v instead")
3181  inline constexpr bool is_pod_v = is_pod<_Tp>::value;
3182 template <typename _Tp>
3183  _GLIBCXX17_DEPRECATED
3184  inline constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
3185 #pragma GCC diagnostic pop
3186  template <typename _Tp>
3187  inline constexpr bool is_empty_v = is_empty<_Tp>::value;
3188 template <typename _Tp>
3189  inline constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
3190 template <typename _Tp>
3191  inline constexpr bool is_abstract_v = is_abstract<_Tp>::value;
3192 template <typename _Tp>
3193  inline constexpr bool is_final_v = is_final<_Tp>::value;
3194 template <typename _Tp>
3195  inline constexpr bool is_signed_v = is_signed<_Tp>::value;
3196 template <typename _Tp>
3197  inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
3198 template <typename _Tp, typename... _Args>
3199  inline constexpr bool is_constructible_v =
3200  is_constructible<_Tp, _Args...>::value;
3201 template <typename _Tp>
3202  inline constexpr bool is_default_constructible_v =
3204 template <typename _Tp>
3205  inline constexpr bool is_copy_constructible_v =
3207 template <typename _Tp>
3208  inline constexpr bool is_move_constructible_v =
3210 template <typename _Tp, typename _Up>
3211  inline constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
3212 template <typename _Tp>
3213  inline constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
3214 template <typename _Tp>
3215  inline constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
3216 template <typename _Tp>
3217  inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
3218 template <typename _Tp, typename... _Args>
3219  inline constexpr bool is_trivially_constructible_v =
3220  is_trivially_constructible<_Tp, _Args...>::value;
3221 template <typename _Tp>
3222  inline constexpr bool is_trivially_default_constructible_v =
3224 template <typename _Tp>
3225  inline constexpr bool is_trivially_copy_constructible_v =
3227 template <typename _Tp>
3228  inline constexpr bool is_trivially_move_constructible_v =
3230 template <typename _Tp, typename _Up>
3231  inline constexpr bool is_trivially_assignable_v =
3233 template <typename _Tp>
3234  inline constexpr bool is_trivially_copy_assignable_v =
3236 template <typename _Tp>
3237  inline constexpr bool is_trivially_move_assignable_v =
3239 template <typename _Tp>
3240  inline constexpr bool is_trivially_destructible_v =
3242 template <typename _Tp, typename... _Args>
3243  inline constexpr bool is_nothrow_constructible_v =
3244  is_nothrow_constructible<_Tp, _Args...>::value;
3245 template <typename _Tp>
3246  inline constexpr bool is_nothrow_default_constructible_v =
3248 template <typename _Tp>
3249  inline constexpr bool is_nothrow_copy_constructible_v =
3251 template <typename _Tp>
3252  inline constexpr bool is_nothrow_move_constructible_v =
3254 template <typename _Tp, typename _Up>
3255  inline constexpr bool is_nothrow_assignable_v =
3257 template <typename _Tp>
3258  inline constexpr bool is_nothrow_copy_assignable_v =
3260 template <typename _Tp>
3261  inline constexpr bool is_nothrow_move_assignable_v =
3263 template <typename _Tp>
3264  inline constexpr bool is_nothrow_destructible_v =
3266 template <typename _Tp>
3267  inline constexpr bool has_virtual_destructor_v =
3269 template <typename _Tp>
3270  inline constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
3271 template <typename _Tp>
3272  inline constexpr size_t rank_v = rank<_Tp>::value;
3273 template <typename _Tp, unsigned _Idx = 0>
3274  inline constexpr size_t extent_v = extent<_Tp, _Idx>::value;
3275 #ifdef _GLIBCXX_HAVE_BUILTIN_IS_SAME
3276 template <typename _Tp, typename _Up>
3277  inline constexpr bool is_same_v = __is_same(_Tp, _Up);
3278 #else
3279 template <typename _Tp, typename _Up>
3280  inline constexpr bool is_same_v = std::is_same<_Tp, _Up>::value;
3281 #endif
3282 template <typename _Base, typename _Derived>
3283  inline constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
3284 template <typename _From, typename _To>
3285  inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
3286 template<typename _Fn, typename... _Args>
3287  inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
3288 template<typename _Fn, typename... _Args>
3289  inline constexpr bool is_nothrow_invocable_v
3290  = is_nothrow_invocable<_Fn, _Args...>::value;
3291 template<typename _Ret, typename _Fn, typename... _Args>
3292  inline constexpr bool is_invocable_r_v
3293  = is_invocable_r<_Ret, _Fn, _Args...>::value;
3294 template<typename _Ret, typename _Fn, typename... _Args>
3295  inline constexpr bool is_nothrow_invocable_r_v
3296  = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3297 /// @}
3298 
3299 #ifdef _GLIBCXX_HAVE_BUILTIN_HAS_UNIQ_OBJ_REP
3300 # define __cpp_lib_has_unique_object_representations 201606L
3301  /// has_unique_object_representations
3302  /// @since C++17
3303  template<typename _Tp>
3305  : bool_constant<__has_unique_object_representations(
3306  remove_cv_t<remove_all_extents_t<_Tp>>
3307  )>
3308  {
3309  static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
3310  "template argument must be a complete class or an unbounded array");
3311  };
3312 
3313  /// @ingroup variable_templates
3314  template<typename _Tp>
3315  inline constexpr bool has_unique_object_representations_v
3317 #endif
3318 
3319 #ifdef _GLIBCXX_HAVE_BUILTIN_IS_AGGREGATE
3320 # define __cpp_lib_is_aggregate 201703L
3321  /// is_aggregate
3322  /// @since C++17
3323  template<typename _Tp>
3325  : bool_constant<__is_aggregate(remove_cv_t<_Tp>)>
3326  { };
3327 
3328  /// @ingroup variable_templates
3329  template<typename _Tp>
3330  inline constexpr bool is_aggregate_v = is_aggregate<_Tp>::value;
3331 #endif
3332 #endif // C++17
3333 
3334 #if __cplusplus >= 202002L
3335 
3336  /** * Remove references and cv-qualifiers.
3337  * @since C++20
3338  * @{
3339  */
3340 #define __cpp_lib_remove_cvref 201711L
3341 
3342  template<typename _Tp>
3343  struct remove_cvref
3344  : remove_cv<_Tp>
3345  { };
3346 
3347  template<typename _Tp>
3348  struct remove_cvref<_Tp&>
3349  : remove_cv<_Tp>
3350  { };
3351 
3352  template<typename _Tp>
3353  struct remove_cvref<_Tp&&>
3354  : remove_cv<_Tp>
3355  { };
3356 
3357  template<typename _Tp>
3358  using remove_cvref_t = typename remove_cvref<_Tp>::type;
3359  /// @}
3360 
3361  /** * Identity metafunction.
3362  * @since C++20
3363  * @{
3364  */
3365 #define __cpp_lib_type_identity 201806L
3366  template<typename _Tp>
3367  struct type_identity { using type = _Tp; };
3368 
3369  template<typename _Tp>
3370  using type_identity_t = typename type_identity<_Tp>::type;
3371  /// @}
3372 
3373 #define __cpp_lib_unwrap_ref 201811L
3374 
3375  /** Unwrap a reference_wrapper
3376  * @since C++20
3377  * @{
3378  */
3379  template<typename _Tp>
3380  struct unwrap_reference { using type = _Tp; };
3381 
3382  template<typename _Tp>
3383  struct unwrap_reference<reference_wrapper<_Tp>> { using type = _Tp&; };
3384 
3385  template<typename _Tp>
3386  using unwrap_reference_t = typename unwrap_reference<_Tp>::type;
3387  /// @}
3388 
3389  /** Decay type and if it's a reference_wrapper, unwrap it
3390  * @since C++20
3391  * @{
3392  */
3393  template<typename _Tp>
3394  struct unwrap_ref_decay { using type = unwrap_reference_t<decay_t<_Tp>>; };
3395 
3396  template<typename _Tp>
3397  using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
3398  /// @}
3399 
3400 #define __cpp_lib_bounded_array_traits 201902L
3401 
3402  /// True for a type that is an array of known bound.
3403  /// @since C++20
3404  template<typename _Tp>
3406  : public __is_array_known_bounds<_Tp>
3407  { };
3408 
3409  /// True for a type that is an array of unknown bound.
3410  /// @since C++20
3411  template<typename _Tp>
3413  : public __is_array_unknown_bounds<_Tp>
3414  { };
3415 
3416  /// @ingroup variable_templates
3417  /// @since C++20
3418  template<typename _Tp>
3419  inline constexpr bool is_bounded_array_v
3421 
3422  /// @ingroup variable_templates
3423  /// @since C++20
3424  template<typename _Tp>
3425  inline constexpr bool is_unbounded_array_v
3427 
3428 #if __has_builtin(__is_layout_compatible)
3429 
3430  /// @since C++20
3431  template<typename _Tp, typename _Up>
3433  : bool_constant<__is_layout_compatible(_Tp, _Up)>
3434  { };
3435 
3436  /// @ingroup variable_templates
3437  /// @since C++20
3438  template<typename _Tp, typename _Up>
3439  constexpr bool is_layout_compatible_v
3440  = __is_layout_compatible(_Tp, _Up);
3441 
3442 #if __has_builtin(__builtin_is_corresponding_member)
3443 #define __cpp_lib_is_layout_compatible 201907L
3444 
3445  /// @since C++20
3446  template<typename _S1, typename _S2, typename _M1, typename _M2>
3447  constexpr bool
3448  is_corresponding_member(_M1 _S1::*__m1, _M2 _S2::*__m2) noexcept
3449  { return __builtin_is_corresponding_member(__m1, __m2); }
3450 #endif
3451 #endif
3452 
3453 #if __has_builtin(__is_pointer_interconvertible_base_of)
3454  /// True if `_Derived` is standard-layout and has a base class of type `_Base`
3455  /// @since C++20
3456  template<typename _Base, typename _Derived>
3458  : bool_constant<__is_pointer_interconvertible_base_of(_Base, _Derived)>
3459  { };
3460 
3461  /// @ingroup variable_templates
3462  /// @since C++20
3463  template<typename _Base, typename _Derived>
3465  = __is_pointer_interconvertible_base_of(_Base, _Derived);
3466 
3467 #if __has_builtin(__builtin_is_pointer_interconvertible_with_class)
3468 #define __cpp_lib_is_pointer_interconvertible 201907L
3469 
3470  /// True if `__mp` points to the first member of a standard-layout type
3471  /// @returns true if `s.*__mp` is pointer-interconvertible with `s`
3472  /// @since C++20
3473  template<typename _Tp, typename _Mem>
3474  constexpr bool
3475  is_pointer_interconvertible_with_class(_Mem _Tp::*__mp) noexcept
3476  { return __builtin_is_pointer_interconvertible_with_class(__mp); }
3477 #endif
3478 #endif
3479 
3480 #if __cplusplus > 202002L
3481 #define __cpp_lib_is_scoped_enum 202011L
3482 
3483  /// True if the type is a scoped enumeration type.
3484  /// @since C++23
3485 
3486  template<typename _Tp>
3487  struct is_scoped_enum
3488  : false_type
3489  { };
3490 
3491  template<typename _Tp>
3492  requires __is_enum(_Tp)
3493  && requires(_Tp __t) { __t = __t; } // fails if incomplete
3494  struct is_scoped_enum<_Tp>
3495  : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3496  { };
3497 
3498  // FIXME remove this partial specialization and use remove_cv_t<_Tp> above
3499  // when PR c++/99968 is fixed.
3500  template<typename _Tp>
3501  requires __is_enum(_Tp)
3502  && requires(_Tp __t) { __t = __t; } // fails if incomplete
3503  struct is_scoped_enum<const _Tp>
3504  : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3505  { };
3506 
3507  /// @ingroup variable_templates
3508  /// @since C++23
3509  template<typename _Tp>
3510  inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
3511 
3512 #endif // C++23
3513 
3514 #if _GLIBCXX_HAVE_IS_CONSTANT_EVALUATED
3515 #define __cpp_lib_is_constant_evaluated 201811L
3516 
3517  /// Returns true only when called during constant evaluation.
3518  /// @since C++20
3519  constexpr inline bool
3521  {
3522 #if __cpp_if_consteval >= 202106L
3523  if consteval { return true; } else { return false; }
3524 #else
3525  return __builtin_is_constant_evaluated();
3526 #endif
3527  }
3528 #endif
3529 
3530  /// @cond undocumented
3531  template<typename _From, typename _To>
3532  using __copy_cv = typename __match_cv_qualifiers<_From, _To>::__type;
3533 
3534  template<typename _Xp, typename _Yp>
3535  using __cond_res
3536  = decltype(false ? declval<_Xp(&)()>()() : declval<_Yp(&)()>()());
3537 
3538  template<typename _Ap, typename _Bp, typename = void>
3539  struct __common_ref_impl
3540  { };
3541 
3542  // [meta.trans.other], COMMON-REF(A, B)
3543  template<typename _Ap, typename _Bp>
3544  using __common_ref = typename __common_ref_impl<_Ap, _Bp>::type;
3545 
3546  // COND-RES(COPYCV(X, Y) &, COPYCV(Y, X) &)
3547  template<typename _Xp, typename _Yp>
3548  using __condres_cvref
3549  = __cond_res<__copy_cv<_Xp, _Yp>&, __copy_cv<_Yp, _Xp>&>;
3550 
3551  // If A and B are both lvalue reference types, ...
3552  template<typename _Xp, typename _Yp>
3553  struct __common_ref_impl<_Xp&, _Yp&, __void_t<__condres_cvref<_Xp, _Yp>>>
3554  : enable_if<is_reference_v<__condres_cvref<_Xp, _Yp>>,
3555  __condres_cvref<_Xp, _Yp>>
3556  { };
3557 
3558  // let C be remove_reference_t<COMMON-REF(X&, Y&)>&&
3559  template<typename _Xp, typename _Yp>
3560  using __common_ref_C = remove_reference_t<__common_ref<_Xp&, _Yp&>>&&;
3561 
3562  // If A and B are both rvalue reference types, ...
3563  template<typename _Xp, typename _Yp>
3564  struct __common_ref_impl<_Xp&&, _Yp&&,
3565  _Require<is_convertible<_Xp&&, __common_ref_C<_Xp, _Yp>>,
3566  is_convertible<_Yp&&, __common_ref_C<_Xp, _Yp>>>>
3567  { using type = __common_ref_C<_Xp, _Yp>; };
3568 
3569  // let D be COMMON-REF(const X&, Y&)
3570  template<typename _Xp, typename _Yp>
3571  using __common_ref_D = __common_ref<const _Xp&, _Yp&>;
3572 
3573  // If A is an rvalue reference and B is an lvalue reference, ...
3574  template<typename _Xp, typename _Yp>
3575  struct __common_ref_impl<_Xp&&, _Yp&,
3576  _Require<is_convertible<_Xp&&, __common_ref_D<_Xp, _Yp>>>>
3577  { using type = __common_ref_D<_Xp, _Yp>; };
3578 
3579  // If A is an lvalue reference and B is an rvalue reference, ...
3580  template<typename _Xp, typename _Yp>
3581  struct __common_ref_impl<_Xp&, _Yp&&>
3582  : __common_ref_impl<_Yp&&, _Xp&>
3583  { };
3584  /// @endcond
3585 
3586  template<typename _Tp, typename _Up,
3587  template<typename> class _TQual, template<typename> class _UQual>
3588  struct basic_common_reference
3589  { };
3590 
3591  /// @cond undocumented
3592  template<typename _Tp>
3593  struct __xref
3594  { template<typename _Up> using __type = __copy_cv<_Tp, _Up>; };
3595 
3596  template<typename _Tp>
3597  struct __xref<_Tp&>
3598  { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&; };
3599 
3600  template<typename _Tp>
3601  struct __xref<_Tp&&>
3602  { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&&; };
3603 
3604  template<typename _Tp1, typename _Tp2>
3605  using __basic_common_ref
3606  = typename basic_common_reference<remove_cvref_t<_Tp1>,
3607  remove_cvref_t<_Tp2>,
3608  __xref<_Tp1>::template __type,
3609  __xref<_Tp2>::template __type>::type;
3610  /// @endcond
3611 
3612  template<typename... _Tp>
3613  struct common_reference;
3614 
3615  template<typename... _Tp>
3616  using common_reference_t = typename common_reference<_Tp...>::type;
3617 
3618  // If sizeof...(T) is zero, there shall be no member type.
3619  template<>
3620  struct common_reference<>
3621  { };
3622 
3623  // If sizeof...(T) is one ...
3624  template<typename _Tp0>
3625  struct common_reference<_Tp0>
3626  { using type = _Tp0; };
3627 
3628  /// @cond undocumented
3629  template<typename _Tp1, typename _Tp2, int _Bullet = 1, typename = void>
3630  struct __common_reference_impl
3631  : __common_reference_impl<_Tp1, _Tp2, _Bullet + 1>
3632  { };
3633 
3634  // If sizeof...(T) is two ...
3635  template<typename _Tp1, typename _Tp2>
3636  struct common_reference<_Tp1, _Tp2>
3637  : __common_reference_impl<_Tp1, _Tp2>
3638  { };
3639 
3640  // If T1 and T2 are reference types and COMMON-REF(T1, T2) is well-formed, ...
3641  template<typename _Tp1, typename _Tp2>
3642  struct __common_reference_impl<_Tp1&, _Tp2&, 1,
3643  void_t<__common_ref<_Tp1&, _Tp2&>>>
3644  { using type = __common_ref<_Tp1&, _Tp2&>; };
3645 
3646  template<typename _Tp1, typename _Tp2>
3647  struct __common_reference_impl<_Tp1&&, _Tp2&&, 1,
3648  void_t<__common_ref<_Tp1&&, _Tp2&&>>>
3649  { using type = __common_ref<_Tp1&&, _Tp2&&>; };
3650 
3651  template<typename _Tp1, typename _Tp2>
3652  struct __common_reference_impl<_Tp1&, _Tp2&&, 1,
3653  void_t<__common_ref<_Tp1&, _Tp2&&>>>
3654  { using type = __common_ref<_Tp1&, _Tp2&&>; };
3655 
3656  template<typename _Tp1, typename _Tp2>
3657  struct __common_reference_impl<_Tp1&&, _Tp2&, 1,
3658  void_t<__common_ref<_Tp1&&, _Tp2&>>>
3659  { using type = __common_ref<_Tp1&&, _Tp2&>; };
3660 
3661  // Otherwise, if basic_common_reference<...>::type is well-formed, ...
3662  template<typename _Tp1, typename _Tp2>
3663  struct __common_reference_impl<_Tp1, _Tp2, 2,
3664  void_t<__basic_common_ref<_Tp1, _Tp2>>>
3665  { using type = __basic_common_ref<_Tp1, _Tp2>; };
3666 
3667  // Otherwise, if COND-RES(T1, T2) is well-formed, ...
3668  template<typename _Tp1, typename _Tp2>
3669  struct __common_reference_impl<_Tp1, _Tp2, 3,
3670  void_t<__cond_res<_Tp1, _Tp2>>>
3671  { using type = __cond_res<_Tp1, _Tp2>; };
3672 
3673  // Otherwise, if common_type_t<T1, T2> is well-formed, ...
3674  template<typename _Tp1, typename _Tp2>
3675  struct __common_reference_impl<_Tp1, _Tp2, 4,
3676  void_t<common_type_t<_Tp1, _Tp2>>>
3677  { using type = common_type_t<_Tp1, _Tp2>; };
3678 
3679  // Otherwise, there shall be no member type.
3680  template<typename _Tp1, typename _Tp2>
3681  struct __common_reference_impl<_Tp1, _Tp2, 5, void>
3682  { };
3683 
3684  // Otherwise, if sizeof...(T) is greater than two, ...
3685  template<typename _Tp1, typename _Tp2, typename... _Rest>
3686  struct common_reference<_Tp1, _Tp2, _Rest...>
3687  : __common_type_fold<common_reference<_Tp1, _Tp2>,
3688  __common_type_pack<_Rest...>>
3689  { };
3690 
3691  // Reuse __common_type_fold for common_reference<T1, T2, Rest...>
3692  template<typename _Tp1, typename _Tp2, typename... _Rest>
3693  struct __common_type_fold<common_reference<_Tp1, _Tp2>,
3694  __common_type_pack<_Rest...>,
3695  void_t<common_reference_t<_Tp1, _Tp2>>>
3696  : public common_reference<common_reference_t<_Tp1, _Tp2>, _Rest...>
3697  { };
3698  /// @endcond
3699 
3700 #endif // C++2a
3701 
3702  /// @} group metaprogramming
3703 
3704 _GLIBCXX_END_NAMESPACE_VERSION
3705 } // namespace std
3706 
3707 #endif // C++11
3708 
3709 #endif // _GLIBCXX_TYPE_TRAITS
typename type_identity< _Tp >::type type_identity_t
Definition: type_traits:3370
constexpr bool is_corresponding_member(_M1 _S1::*__m1, _M2 _S2::*__m2) noexcept
Definition: type_traits:3448
typename remove_reference< _Tp >::type remove_reference_t
Alias template for remove_reference.
Definition: type_traits:1664
typename result_of< _Tp >::type result_of_t
Alias template for result_of.
Definition: type_traits:2624
constexpr bool is_nothrow_swappable_v
is_nothrow_swappable_v
Definition: type_traits:2794
typename add_rvalue_reference< _Tp >::type add_rvalue_reference_t
Alias template for add_rvalue_reference.
Definition: type_traits:1672
integral_constant< bool, __v > bool_constant
Alias template for compile-time boolean constant types.
Definition: type_traits:98
constexpr bool is_nothrow_convertible_v
is_nothrow_convertible_v
Definition: type_traits:1531
typename make_unsigned< _Tp >::type make_unsigned_t
Alias template for make_unsigned.
Definition: type_traits:2003
void void_t
A metafunction that always yields void, used for detecting valid types.
Definition: type_traits:2630
constexpr bool is_swappable_v
is_swappable_v
Definition: type_traits:2789
typename aligned_storage< _Len, _Align >::type aligned_storage_t
Alias template for aligned_storage.
Definition: type_traits:2597
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:82
typename remove_cv< _Tp >::type remove_cv_t
Alias template for remove_cv.
Definition: type_traits:1603
typename remove_all_extents< _Tp >::type remove_all_extents_t
Alias template for remove_all_extents.
Definition: type_traits:2041
typename common_type< _Tp... >::type common_type_t
Alias template for common_type.
Definition: type_traits:2616
typename conditional< _Cond, _Iftrue, _Iffalse >::type conditional_t
Alias template for conditional.
Definition: type_traits:2612
typename add_const< _Tp >::type add_const_t
Alias template for add_const.
Definition: type_traits:1607
typename remove_pointer< _Tp >::type remove_pointer_t
Alias template for remove_pointer.
Definition: type_traits:2078
typename add_cv< _Tp >::type add_cv_t
Alias template for add_cv.
Definition: type_traits:1615
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:85
typename remove_const< _Tp >::type remove_const_t
Alias template for remove_const.
Definition: type_traits:1595
constexpr bool is_swappable_with_v
is_swappable_with_v
Definition: type_traits:2885
typename add_volatile< _Tp >::type add_volatile_t
Alias template for add_volatile.
Definition: type_traits:1611
typename remove_volatile< _Tp >::type remove_volatile_t
Alias template for remove_volatile.
Definition: type_traits:1599
typename add_lvalue_reference< _Tp >::type add_lvalue_reference_t
Alias template for add_lvalue_reference.
Definition: type_traits:1668
typename remove_cvref< _Tp >::type remove_cvref_t
Definition: type_traits:3358
typename add_pointer< _Tp >::type add_pointer_t
Alias template for add_pointer.
Definition: type_traits:2082
typename remove_extent< _Tp >::type remove_extent_t
Alias template for remove_extent.
Definition: type_traits:2037
constexpr bool is_constant_evaluated() noexcept
Returns true only when called during constant evaluation.
Definition: type_traits:3520
typename underlying_type< _Tp >::type underlying_type_t
Alias template for underlying_type.
Definition: type_traits:2620
typename decay< _Tp >::type decay_t
Alias template for decay.
Definition: type_traits:2604
typename make_signed< _Tp >::type make_signed_t
Alias template for make_signed.
Definition: type_traits:1999
constexpr bool is_pointer_interconvertible_with_class(_Mem _Tp::*__mp) noexcept
True if __mp points to the first member of a standard-layout type.
Definition: type_traits:3475
typename enable_if< _Cond, _Tp >::type enable_if_t
Alias template for enable_if.
Definition: type_traits:2608
typename invoke_result< _Fn, _Args... >::type invoke_result_t
std::invoke_result_t
Definition: type_traits:3041
constexpr bool is_nothrow_swappable_with_v
is_nothrow_swappable_with_v
Definition: type_traits:2890
constexpr bool is_bounded_array_v
Definition: type_traits:3420
constexpr bool is_unbounded_array_v
Definition: type_traits:3426
constexpr bool is_layout_compatible_v
Definition: type_traits:3440
constexpr bool is_pointer_interconvertible_base_of_v
Definition: type_traits:3465
auto declval() noexcept -> decltype(__declval< _Tp >(0))
Definition: type_traits:2387
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:429
ISO C++ entities toplevel namespace is std.
Primary class template for reference_wrapper.
Definition: refwrap.h:309
integral_constant
Definition: type_traits:63
is_reference
Definition: type_traits:581
is_function
Definition: type_traits:541
is_void
Definition: type_traits:287
remove_cv
Definition: type_traits:1557
is_const
Definition: type_traits:707
is_integral
Definition: type_traits:415
is_floating_point
Definition: type_traits:445
is_array
Definition: type_traits:450
is_pointer
Definition: type_traits:472
is_lvalue_reference
Definition: type_traits:477
is_rvalue_reference
Definition: type_traits:486
is_member_object_pointer
Definition: type_traits:504
is_member_function_pointer
Definition: type_traits:518
is_enum
Definition: type_traits:524
is_union
Definition: type_traits:530
is_class
Definition: type_traits:536
is_null_pointer (LWG 2247).
Definition: type_traits:565
__is_nullptr_t (deprecated extension).
Definition: type_traits:572
is_arithmetic
Definition: type_traits:587
is_fundamental
Definition: type_traits:594
is_object
Definition: type_traits:601
is_member_pointer
Definition: type_traits:632
is_scalar
Definition: type_traits:611
is_compound
Definition: type_traits:616
is_same
Definition: type_traits:1435
is_volatile
Definition: type_traits:716
is_trivial
Definition: type_traits:726
is_trivially_copyable
Definition: type_traits:735
is_standard_layout
Definition: type_traits:744
is_empty
Definition: type_traits:782
is_polymorphic
Definition: type_traits:788
is_final
Definition: type_traits:797
is_abstract
Definition: type_traits:804
is_signed
Definition: type_traits:822
is_unsigned
Definition: type_traits:828
extent
Definition: type_traits:1408
remove_all_extents
Definition: type_traits:2024
is_destructible
Definition: type_traits:909
is_nothrow_destructible
Definition: type_traits:963
is_constructible
Definition: type_traits:979
is_default_constructible
Definition: type_traits:988
is_copy_constructible
Definition: type_traits:1011
is_move_constructible
Definition: type_traits:1034
is_nothrow_constructible
Definition: type_traits:1049
is_nothrow_default_constructible
Definition: type_traits:1058
is_nothrow_copy_constructible
Definition: type_traits:1081
is_nothrow_move_constructible
Definition: type_traits:1104
is_assignable
Definition: type_traits:1113
is_copy_assignable
Definition: type_traits:1134
is_move_assignable
Definition: type_traits:1155
is_nothrow_assignable
Definition: type_traits:1168
is_nothrow_copy_assignable
Definition: type_traits:1189
is_nothrow_move_assignable
Definition: type_traits:1210
is_trivially_constructible
Definition: type_traits:1219
is_trivially_default_constructible
Definition: type_traits:1228
is_trivially_copy_constructible
Definition: type_traits:1281
is_trivially_move_constructible
Definition: type_traits:1304
is_trivially_assignable
Definition: type_traits:1313
is_trivially_copy_assignable
Definition: type_traits:1334
is_trivially_move_assignable
Definition: type_traits:1355
is_trivially_destructible
Definition: type_traits:1365
has_virtual_destructor
Definition: type_traits:1375
alignment_of
Definition: type_traits:1387
is_base_of
Definition: type_traits:1448
is_convertible
Definition: type_traits:1484
is_nothrow_convertible
Definition: type_traits:1526
remove_const
Definition: type_traits:1539
remove_volatile
Definition: type_traits:1548
add_const
Definition: type_traits:1574
add_volatile
Definition: type_traits:1579
add_cv
Definition: type_traits:1584
remove_reference
Definition: type_traits:1623
add_lvalue_reference
Definition: type_traits:1645
add_rvalue_reference
Definition: type_traits:1659
make_unsigned
Definition: type_traits:1860
make_signed
Definition: type_traits:1990
remove_extent
Definition: type_traits:2011
remove_pointer
Definition: type_traits:2058
add_pointer
Definition: type_traits:2073
Alignment type.
Definition: type_traits:2108
Provide aligned storage for types.
Definition: type_traits:2146
aligned_storage< _S_len, alignment_value >::type type
The storage.
Definition: type_traits:2157
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:2223
Define a member typedef type to one of two argument types.
Definition: type_traits:2250
common_type
Definition: type_traits:2259
The underlying type of an enum.
Definition: type_traits:2372
result_of
Definition: type_traits:2396
Metafunctions used for detecting swappable types: p0185r1.
Definition: type_traits:2772
is_nothrow_swappable
Definition: type_traits:2781
is_swappable_with
Definition: type_traits:2864
is_nothrow_swappable_with
Definition: type_traits:2875
std::invoke_result
Definition: type_traits:3031
std::is_invocable
Definition: type_traits:3047
std::is_invocable_r
Definition: type_traits:3059
std::is_nothrow_invocable
Definition: type_traits:3074
std::is_nothrow_invocable_r
Definition: type_traits:3093
has_unique_object_representations
Definition: type_traits:3308
is_aggregate
Definition: type_traits:3326
True for a type that is an array of known bound.
Definition: type_traits:3407
True for a type that is an array of unknown bound.
Definition: type_traits:3414
True if _Derived is standard-layout and has a base class of type _Base
Definition: type_traits:3459