1// C++11 <type_traits> -*- C++ -*-
3// Copyright (C) 2007-2024 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25/** @file include/type_traits
26 * This is a Standard C++ Library header.
29#ifndef _GLIBCXX_TYPE_TRAITS
30#define _GLIBCXX_TYPE_TRAITS 1
32#pragma GCC system_header
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
38#include <bits/c++config.h>
40#define __glibcxx_want_bool_constant
41#define __glibcxx_want_bounded_array_traits
42#define __glibcxx_want_has_unique_object_representations
43#define __glibcxx_want_integral_constant_callable
44#define __glibcxx_want_is_aggregate
45#define __glibcxx_want_is_constant_evaluated
46#define __glibcxx_want_is_final
47#define __glibcxx_want_is_invocable
48#define __glibcxx_want_is_layout_compatible
49#define __glibcxx_want_is_nothrow_convertible
50#define __glibcxx_want_is_null_pointer
51#define __glibcxx_want_is_pointer_interconvertible
52#define __glibcxx_want_is_scoped_enum
53#define __glibcxx_want_is_swappable
54#define __glibcxx_want_logical_traits
55#define __glibcxx_want_reference_from_temporary
56#define __glibcxx_want_remove_cvref
57#define __glibcxx_want_result_of_sfinae
58#define __glibcxx_want_transformation_trait_aliases
59#define __glibcxx_want_type_identity
60#define __glibcxx_want_type_trait_variable_templates
61#define __glibcxx_want_unwrap_ref
62#define __glibcxx_want_void_t
63#include <bits/version.h>
65namespace std _GLIBCXX_VISIBILITY(default)
67_GLIBCXX_BEGIN_NAMESPACE_VERSION
69 template<typename _Tp>
70 class reference_wrapper;
73 * @defgroup metaprogramming Metaprogramming
76 * Template utilities for compile-time introspection and modification,
77 * including type classification traits, type property inspection traits
78 * and type transformation traits.
86 template<typename _Tp, _Tp __v>
87 struct integral_constant
89 static constexpr _Tp value = __v;
90 using value_type = _Tp;
91 using type = integral_constant<_Tp, __v>;
92 constexpr operator value_type() const noexcept { return value; }
94#ifdef __cpp_lib_integral_constant_callable // C++ >= 14
95 constexpr value_type operator()() const noexcept { return value; }
99#if ! __cpp_inline_variables
100 template<typename _Tp, _Tp __v>
101 constexpr _Tp integral_constant<_Tp, __v>::value;
104 /// @cond undocumented
105 /// bool_constant for C++11
107 using __bool_constant = integral_constant<bool, __v>;
110 /// The type used as a compile-time boolean with true value.
111 using true_type = __bool_constant<true>;
113 /// The type used as a compile-time boolean with false value.
114 using false_type = __bool_constant<false>;
116#ifdef __cpp_lib_bool_constant // C++ >= 17
117 /// Alias template for compile-time boolean constant types.
120 using bool_constant = __bool_constant<__v>;
123 // Metaprogramming helper types.
126 /// Define a member typedef `type` only if a boolean constant is true.
127 template<bool, typename _Tp = void>
131 // Partial specialization for true.
132 template<typename _Tp>
133 struct enable_if<true, _Tp>
134 { using type = _Tp; };
136 // __enable_if_t (std::enable_if_t for C++11)
137 template<bool _Cond, typename _Tp = void>
138 using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
143 template<typename _Tp, typename>
148 struct __conditional<false>
150 template<typename, typename _Up>
154 // More efficient version of std::conditional_t for internal use (and C++11)
155 template<bool _Cond, typename _If, typename _Else>
156 using __conditional_t
157 = typename __conditional<_Cond>::template type<_If, _Else>;
159 /// @cond undocumented
160 template <typename _Type>
161 struct __type_identity
162 { using type = _Type; };
164 template<typename _Tp>
165 using __type_identity_t = typename __type_identity<_Tp>::type;
169 // A variadic alias template that resolves to its first argument.
170 template<typename _Tp, typename...>
171 using __first_t = _Tp;
173 // These are deliberately not defined.
174 template<typename... _Bn>
175 auto __or_fn(int) -> __first_t<false_type,
176 __enable_if_t<!bool(_Bn::value)>...>;
178 template<typename... _Bn>
179 auto __or_fn(...) -> true_type;
181 template<typename... _Bn>
182 auto __and_fn(int) -> __first_t<true_type,
183 __enable_if_t<bool(_Bn::value)>...>;
185 template<typename... _Bn>
186 auto __and_fn(...) -> false_type;
187 } // namespace detail
189 // Like C++17 std::dis/conjunction, but usable in C++11 and resolves
190 // to either true_type or false_type which allows for a more efficient
191 // implementation that avoids recursive class template instantiation.
192 template<typename... _Bn>
194 : decltype(__detail::__or_fn<_Bn...>(0))
197 template<typename... _Bn>
199 : decltype(__detail::__and_fn<_Bn...>(0))
202 template<typename _Pp>
204 : __bool_constant<!bool(_Pp::value)>
208#ifdef __cpp_lib_logical_traits // C++ >= 17
210 /// @cond undocumented
211 template<typename... _Bn>
212 inline constexpr bool __or_v = __or_<_Bn...>::value;
213 template<typename... _Bn>
214 inline constexpr bool __and_v = __and_<_Bn...>::value;
218 template<typename /* = void */, typename _B1, typename... _Bn>
219 struct __disjunction_impl
220 { using type = _B1; };
222 template<typename _B1, typename _B2, typename... _Bn>
223 struct __disjunction_impl<__enable_if_t<!bool(_B1::value)>, _B1, _B2, _Bn...>
224 { using type = typename __disjunction_impl<void, _B2, _Bn...>::type; };
226 template<typename /* = void */, typename _B1, typename... _Bn>
227 struct __conjunction_impl
228 { using type = _B1; };
230 template<typename _B1, typename _B2, typename... _Bn>
231 struct __conjunction_impl<__enable_if_t<bool(_B1::value)>, _B1, _B2, _Bn...>
232 { using type = typename __conjunction_impl<void, _B2, _Bn...>::type; };
233 } // namespace __detail
236 template<typename... _Bn>
238 : __detail::__conjunction_impl<void, _Bn...>::type
246 template<typename... _Bn>
248 : __detail::__disjunction_impl<void, _Bn...>::type
256 template<typename _Pp>
261 /** @ingroup variable_templates
264 template<typename... _Bn>
265 inline constexpr bool conjunction_v = conjunction<_Bn...>::value;
267 template<typename... _Bn>
268 inline constexpr bool disjunction_v = disjunction<_Bn...>::value;
270 template<typename _Pp>
271 inline constexpr bool negation_v = negation<_Pp>::value;
274#endif // __cpp_lib_logical_traits
276 // Forward declarations
288 /// @cond undocumented
290 struct __is_array_unknown_bounds;
292 // Helper functions that return false_type for incomplete classes,
293 // incomplete unions and arrays of known bound from those.
295 template <typename _Tp, size_t = sizeof(_Tp)>
296 constexpr true_type __is_complete_or_unbounded(__type_identity<_Tp>)
299 template <typename _TypeIdentity,
300 typename _NestedType = typename _TypeIdentity::type>
301 constexpr typename __or_<
302 is_reference<_NestedType>,
303 is_function<_NestedType>,
304 is_void<_NestedType>,
305 __is_array_unknown_bounds<_NestedType>
306 >::type __is_complete_or_unbounded(_TypeIdentity)
309 // __remove_cv_t (std::remove_cv_t for C++11).
310 template<typename _Tp>
311 using __remove_cv_t = typename remove_cv<_Tp>::type;
314 // Primary type categories.
317 template<typename _Tp>
319 : public false_type { };
323 : public true_type { };
326 struct is_void<const void>
327 : public true_type { };
330 struct is_void<volatile void>
331 : public true_type { };
334 struct is_void<const volatile void>
335 : public true_type { };
337 /// @cond undocumented
339 struct __is_integral_helper
340 : public false_type { };
343 struct __is_integral_helper<bool>
344 : public true_type { };
347 struct __is_integral_helper<char>
348 : public true_type { };
351 struct __is_integral_helper<signed char>
352 : public true_type { };
355 struct __is_integral_helper<unsigned char>
356 : public true_type { };
358 // We want is_integral<wchar_t> to be true (and make_signed/unsigned to work)
359 // even when libc doesn't provide working <wchar.h> and related functions,
360 // so don't check _GLIBCXX_USE_WCHAR_T here.
362 struct __is_integral_helper<wchar_t>
363 : public true_type { };
365#ifdef _GLIBCXX_USE_CHAR8_T
367 struct __is_integral_helper<char8_t>
368 : public true_type { };
372 struct __is_integral_helper<char16_t>
373 : public true_type { };
376 struct __is_integral_helper<char32_t>
377 : public true_type { };
380 struct __is_integral_helper<short>
381 : public true_type { };
384 struct __is_integral_helper<unsigned short>
385 : public true_type { };
388 struct __is_integral_helper<int>
389 : public true_type { };
392 struct __is_integral_helper<unsigned int>
393 : public true_type { };
396 struct __is_integral_helper<long>
397 : public true_type { };
400 struct __is_integral_helper<unsigned long>
401 : public true_type { };
404 struct __is_integral_helper<long long>
405 : public true_type { };
408 struct __is_integral_helper<unsigned long long>
409 : public true_type { };
411 // Conditionalizing on __STRICT_ANSI__ here will break any port that
412 // uses one of these types for size_t.
413#if defined(__GLIBCXX_TYPE_INT_N_0)
416 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_0>
417 : public true_type { };
421 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_0>
422 : public true_type { };
424#if defined(__GLIBCXX_TYPE_INT_N_1)
427 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_1>
428 : public true_type { };
432 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_1>
433 : public true_type { };
435#if defined(__GLIBCXX_TYPE_INT_N_2)
438 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_2>
439 : public true_type { };
443 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_2>
444 : public true_type { };
446#if defined(__GLIBCXX_TYPE_INT_N_3)
449 struct __is_integral_helper<__GLIBCXX_TYPE_INT_N_3>
450 : public true_type { };
454 struct __is_integral_helper<unsigned __GLIBCXX_TYPE_INT_N_3>
455 : public true_type { };
460 template<typename _Tp>
462 : public __is_integral_helper<__remove_cv_t<_Tp>>::type
465 /// @cond undocumented
467 struct __is_floating_point_helper
468 : public false_type { };
471 struct __is_floating_point_helper<float>
472 : public true_type { };
475 struct __is_floating_point_helper<double>
476 : public true_type { };
479 struct __is_floating_point_helper<long double>
480 : public true_type { };
482#ifdef __STDCPP_FLOAT16_T__
484 struct __is_floating_point_helper<_Float16>
485 : public true_type { };
488#ifdef __STDCPP_FLOAT32_T__
490 struct __is_floating_point_helper<_Float32>
491 : public true_type { };
494#ifdef __STDCPP_FLOAT64_T__
496 struct __is_floating_point_helper<_Float64>
497 : public true_type { };
500#ifdef __STDCPP_FLOAT128_T__
502 struct __is_floating_point_helper<_Float128>
503 : public true_type { };
506#ifdef __STDCPP_BFLOAT16_T__
508 struct __is_floating_point_helper<__gnu_cxx::__bfloat16_t>
509 : public true_type { };
512#if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128)
514 struct __is_floating_point_helper<__float128>
515 : public true_type { };
519 /// is_floating_point
520 template<typename _Tp>
521 struct is_floating_point
522 : public __is_floating_point_helper<__remove_cv_t<_Tp>>::type
526#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_array)
527 template<typename _Tp>
529 : public __bool_constant<__is_array(_Tp)>
534 : public false_type { };
536 template<typename _Tp, std::size_t _Size>
537 struct is_array<_Tp[_Size]>
538 : public true_type { };
540 template<typename _Tp>
541 struct is_array<_Tp[]>
542 : public true_type { };
546 struct __is_pointer_helper
547 : public false_type { };
549 template<typename _Tp>
550 struct __is_pointer_helper<_Tp*>
551 : public true_type { };
554 template<typename _Tp>
556 : public __is_pointer_helper<__remove_cv_t<_Tp>>::type
559 /// is_lvalue_reference
561 struct is_lvalue_reference
562 : public false_type { };
564 template<typename _Tp>
565 struct is_lvalue_reference<_Tp&>
566 : public true_type { };
568 /// is_rvalue_reference
570 struct is_rvalue_reference
571 : public false_type { };
573 template<typename _Tp>
574 struct is_rvalue_reference<_Tp&&>
575 : public true_type { };
577 /// is_member_object_pointer
578#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_object_pointer)
579 template<typename _Tp>
580 struct is_member_object_pointer
581 : public __bool_constant<__is_member_object_pointer(_Tp)>
585 struct __is_member_object_pointer_helper
586 : public false_type { };
588 template<typename _Tp, typename _Cp>
589 struct __is_member_object_pointer_helper<_Tp _Cp::*>
590 : public __not_<is_function<_Tp>>::type { };
593 template<typename _Tp>
594 struct is_member_object_pointer
595 : public __is_member_object_pointer_helper<__remove_cv_t<_Tp>>::type
599#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_function_pointer)
600 /// is_member_function_pointer
601 template<typename _Tp>
602 struct is_member_function_pointer
603 : public __bool_constant<__is_member_function_pointer(_Tp)>
607 struct __is_member_function_pointer_helper
608 : public false_type { };
610 template<typename _Tp, typename _Cp>
611 struct __is_member_function_pointer_helper<_Tp _Cp::*>
612 : public is_function<_Tp>::type { };
614 /// is_member_function_pointer
615 template<typename _Tp>
616 struct is_member_function_pointer
617 : public __is_member_function_pointer_helper<__remove_cv_t<_Tp>>::type
622 template<typename _Tp>
624 : public __bool_constant<__is_enum(_Tp)>
628 template<typename _Tp>
630 : public __bool_constant<__is_union(_Tp)>
634 template<typename _Tp>
636 : public __bool_constant<__is_class(_Tp)>
640#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function)
641 template<typename _Tp>
643 : public __bool_constant<__is_function(_Tp)>
646 template<typename _Tp>
648 : public __bool_constant<!is_const<const _Tp>::value> { };
650 template<typename _Tp>
651 struct is_function<_Tp&>
652 : public false_type { };
654 template<typename _Tp>
655 struct is_function<_Tp&&>
656 : public false_type { };
659#ifdef __cpp_lib_is_null_pointer // C++ >= 11
660 /// is_null_pointer (LWG 2247).
661 template<typename _Tp>
662 struct is_null_pointer
663 : public false_type { };
666 struct is_null_pointer<std::nullptr_t>
667 : public true_type { };
670 struct is_null_pointer<const std::nullptr_t>
671 : public true_type { };
674 struct is_null_pointer<volatile std::nullptr_t>
675 : public true_type { };
678 struct is_null_pointer<const volatile std::nullptr_t>
679 : public true_type { };
681 /// __is_nullptr_t (deprecated extension).
682 /// @deprecated Non-standard. Use `is_null_pointer` instead.
683 template<typename _Tp>
684 struct __is_nullptr_t
685 : public is_null_pointer<_Tp>
686 { } _GLIBCXX_DEPRECATED_SUGGEST("std::is_null_pointer");
687#endif // __cpp_lib_is_null_pointer
689 // Composite type categories.
692#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_reference)
693 template<typename _Tp>
695 : public __bool_constant<__is_reference(_Tp)>
698 template<typename _Tp>
703 template<typename _Tp>
704 struct is_reference<_Tp&>
708 template<typename _Tp>
709 struct is_reference<_Tp&&>
715 template<typename _Tp>
717 : public __or_<is_integral<_Tp>, is_floating_point<_Tp>>::type
721 template<typename _Tp>
722 struct is_fundamental
723 : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
724 is_null_pointer<_Tp>>::type
728#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_object)
729 template<typename _Tp>
731 : public __bool_constant<__is_object(_Tp)>
734 template<typename _Tp>
736 : public __not_<__or_<is_function<_Tp>, is_reference<_Tp>,
742 struct is_member_pointer;
745 template<typename _Tp>
747 : public __or_<is_arithmetic<_Tp>, is_enum<_Tp>, is_pointer<_Tp>,
748 is_member_pointer<_Tp>, is_null_pointer<_Tp>>::type
752 template<typename _Tp>
754 : public __bool_constant<!is_fundamental<_Tp>::value> { };
756 /// is_member_pointer
757#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_pointer)
758 template<typename _Tp>
759 struct is_member_pointer
760 : public __bool_constant<__is_member_pointer(_Tp)>
763 /// @cond undocumented
764 template<typename _Tp>
765 struct __is_member_pointer_helper
766 : public false_type { };
768 template<typename _Tp, typename _Cp>
769 struct __is_member_pointer_helper<_Tp _Cp::*>
770 : public true_type { };
773 template<typename _Tp>
774 struct is_member_pointer
775 : public __is_member_pointer_helper<__remove_cv_t<_Tp>>::type
779 template<typename, typename>
782 /// @cond undocumented
783 template<typename _Tp, typename... _Types>
784 using __is_one_of = __or_<is_same<_Tp, _Types>...>;
786 // Check if a type is one of the signed integer types.
788 template<typename _Tp>
789 using __is_signed_integer = __is_one_of<__remove_cv_t<_Tp>,
790 signed char, signed short, signed int, signed long,
792#if defined(__GLIBCXX_TYPE_INT_N_0)
793 , signed __GLIBCXX_TYPE_INT_N_0
795#if defined(__GLIBCXX_TYPE_INT_N_1)
796 , signed __GLIBCXX_TYPE_INT_N_1
798#if defined(__GLIBCXX_TYPE_INT_N_2)
799 , signed __GLIBCXX_TYPE_INT_N_2
801#if defined(__GLIBCXX_TYPE_INT_N_3)
802 , signed __GLIBCXX_TYPE_INT_N_3
806 // Check if a type is one of the unsigned integer types.
808 template<typename _Tp>
809 using __is_unsigned_integer = __is_one_of<__remove_cv_t<_Tp>,
810 unsigned char, unsigned short, unsigned int, unsigned long,
812#if defined(__GLIBCXX_TYPE_INT_N_0)
813 , unsigned __GLIBCXX_TYPE_INT_N_0
815#if defined(__GLIBCXX_TYPE_INT_N_1)
816 , unsigned __GLIBCXX_TYPE_INT_N_1
818#if defined(__GLIBCXX_TYPE_INT_N_2)
819 , unsigned __GLIBCXX_TYPE_INT_N_2
821#if defined(__GLIBCXX_TYPE_INT_N_3)
822 , unsigned __GLIBCXX_TYPE_INT_N_3
826 // Check if a type is one of the signed or unsigned integer types.
827 template<typename _Tp>
828 using __is_standard_integer
829 = __or_<__is_signed_integer<_Tp>, __is_unsigned_integer<_Tp>>;
831 // __void_t (std::void_t for C++11)
832 template<typename...> using __void_t = void;
840 : public false_type { };
842 template<typename _Tp>
843 struct is_const<_Tp const>
844 : public true_type { };
849 : public false_type { };
851 template<typename _Tp>
852 struct is_volatile<_Tp volatile>
853 : public true_type { };
856 template<typename _Tp>
858 : public __bool_constant<__is_trivial(_Tp)>
860 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
861 "template argument must be a complete class or an unbounded array");
864 /// is_trivially_copyable
865 template<typename _Tp>
866 struct is_trivially_copyable
867 : public __bool_constant<__is_trivially_copyable(_Tp)>
869 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
870 "template argument must be a complete class or an unbounded array");
873 /// is_standard_layout
874 template<typename _Tp>
875 struct is_standard_layout
876 : public __bool_constant<__is_standard_layout(_Tp)>
878 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
879 "template argument must be a complete class or an unbounded array");
883 * @deprecated Deprecated in C++20.
884 * Use `is_standard_layout && is_trivial` instead.
886 // Could use is_standard_layout && is_trivial instead of the builtin.
887 template<typename _Tp>
889 _GLIBCXX20_DEPRECATED_SUGGEST("is_standard_layout && is_trivial")
891 : public __bool_constant<__is_pod(_Tp)>
893 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
894 "template argument must be a complete class or an unbounded array");
898 * @deprecated Deprecated in C++17, removed in C++20.
899 * The idea of a literal type isn't useful.
901 template<typename _Tp>
903 _GLIBCXX17_DEPRECATED
905 : public __bool_constant<__is_literal_type(_Tp)>
907 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
908 "template argument must be a complete class or an unbounded array");
912 template<typename _Tp>
914 : public __bool_constant<__is_empty(_Tp)>
918 template<typename _Tp>
919 struct is_polymorphic
920 : public __bool_constant<__is_polymorphic(_Tp)>
923#ifdef __cpp_lib_is_final // C++ >= 14
926 template<typename _Tp>
928 : public __bool_constant<__is_final(_Tp)>
933 template<typename _Tp>
935 : public __bool_constant<__is_abstract(_Tp)>
938 /// @cond undocumented
939 template<typename _Tp,
940 bool = is_arithmetic<_Tp>::value>
941 struct __is_signed_helper
942 : public false_type { };
944 template<typename _Tp>
945 struct __is_signed_helper<_Tp, true>
946 : public __bool_constant<_Tp(-1) < _Tp(0)>
951 template<typename _Tp>
953 : public __is_signed_helper<_Tp>::type
957 template<typename _Tp>
959 : public __and_<is_arithmetic<_Tp>, __not_<is_signed<_Tp>>>::type
962 /// @cond undocumented
963 template<typename _Tp, typename _Up = _Tp&&>
967 template<typename _Tp>
972 template<typename _Tp>
973 auto declval() noexcept -> decltype(__declval<_Tp>(0));
976 struct remove_all_extents;
978 /// @cond undocumented
979 template<typename _Tp>
980 struct __is_array_known_bounds
984 template<typename _Tp, size_t _Size>
985 struct __is_array_known_bounds<_Tp[_Size]>
989 template<typename _Tp>
990 struct __is_array_unknown_bounds
994 template<typename _Tp>
995 struct __is_array_unknown_bounds<_Tp[]>
999 // Destructible and constructible type properties.
1001 // In N3290 is_destructible does not say anything about function
1002 // types and abstract types, see LWG 2049. This implementation
1003 // describes function types as non-destructible and all complete
1004 // object types as destructible, iff the explicit destructor
1005 // call expression is wellformed.
1006 struct __do_is_destructible_impl
1008 template<typename _Tp, typename = decltype(declval<_Tp&>().~_Tp())>
1009 static true_type __test(int);
1012 static false_type __test(...);
1015 template<typename _Tp>
1016 struct __is_destructible_impl
1017 : public __do_is_destructible_impl
1019 using type = decltype(__test<_Tp>(0));
1022 template<typename _Tp,
1023 bool = __or_<is_void<_Tp>,
1024 __is_array_unknown_bounds<_Tp>,
1025 is_function<_Tp>>::value,
1026 bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
1027 struct __is_destructible_safe;
1029 template<typename _Tp>
1030 struct __is_destructible_safe<_Tp, false, false>
1031 : public __is_destructible_impl<typename
1032 remove_all_extents<_Tp>::type>::type
1035 template<typename _Tp>
1036 struct __is_destructible_safe<_Tp, true, false>
1037 : public false_type { };
1039 template<typename _Tp>
1040 struct __is_destructible_safe<_Tp, false, true>
1041 : public true_type { };
1045 template<typename _Tp>
1046 struct is_destructible
1047 : public __is_destructible_safe<_Tp>::type
1049 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1050 "template argument must be a complete class or an unbounded array");
1053 /// @cond undocumented
1055 // is_nothrow_destructible requires that is_destructible is
1056 // satisfied as well. We realize that by mimicing the
1057 // implementation of is_destructible but refer to noexcept(expr)
1058 // instead of decltype(expr).
1059 struct __do_is_nt_destructible_impl
1061 template<typename _Tp>
1062 static __bool_constant<noexcept(declval<_Tp&>().~_Tp())>
1066 static false_type __test(...);
1069 template<typename _Tp>
1070 struct __is_nt_destructible_impl
1071 : public __do_is_nt_destructible_impl
1073 using type = decltype(__test<_Tp>(0));
1076 template<typename _Tp,
1077 bool = __or_<is_void<_Tp>,
1078 __is_array_unknown_bounds<_Tp>,
1079 is_function<_Tp>>::value,
1080 bool = __or_<is_reference<_Tp>, is_scalar<_Tp>>::value>
1081 struct __is_nt_destructible_safe;
1083 template<typename _Tp>
1084 struct __is_nt_destructible_safe<_Tp, false, false>
1085 : public __is_nt_destructible_impl<typename
1086 remove_all_extents<_Tp>::type>::type
1089 template<typename _Tp>
1090 struct __is_nt_destructible_safe<_Tp, true, false>
1091 : public false_type { };
1093 template<typename _Tp>
1094 struct __is_nt_destructible_safe<_Tp, false, true>
1095 : public true_type { };
1098 /// is_nothrow_destructible
1099 template<typename _Tp>
1100 struct is_nothrow_destructible
1101 : public __is_nt_destructible_safe<_Tp>::type
1103 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1104 "template argument must be a complete class or an unbounded array");
1107 /// @cond undocumented
1108 template<typename _Tp, typename... _Args>
1109 using __is_constructible_impl
1110 = __bool_constant<__is_constructible(_Tp, _Args...)>;
1113 /// is_constructible
1114 template<typename _Tp, typename... _Args>
1115 struct is_constructible
1116 : public __is_constructible_impl<_Tp, _Args...>
1118 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1119 "template argument must be a complete class or an unbounded array");
1122 /// is_default_constructible
1123 template<typename _Tp>
1124 struct is_default_constructible
1125 : public __is_constructible_impl<_Tp>
1127 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1128 "template argument must be a complete class or an unbounded array");
1131 /// @cond undocumented
1132 template<typename _Tp, typename = void>
1133 struct __add_lvalue_reference_helper
1134 { using type = _Tp; };
1136 template<typename _Tp>
1137 struct __add_lvalue_reference_helper<_Tp, __void_t<_Tp&>>
1138 { using type = _Tp&; };
1140 template<typename _Tp>
1141 using __add_lval_ref_t = typename __add_lvalue_reference_helper<_Tp>::type;
1144 /// is_copy_constructible
1145 template<typename _Tp>
1146 struct is_copy_constructible
1147 : public __is_constructible_impl<_Tp, __add_lval_ref_t<const _Tp>>
1149 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1150 "template argument must be a complete class or an unbounded array");
1153 /// @cond undocumented
1154 template<typename _Tp, typename = void>
1155 struct __add_rvalue_reference_helper
1156 { using type = _Tp; };
1158 template<typename _Tp>
1159 struct __add_rvalue_reference_helper<_Tp, __void_t<_Tp&&>>
1160 { using type = _Tp&&; };
1162 template<typename _Tp>
1163 using __add_rval_ref_t = typename __add_rvalue_reference_helper<_Tp>::type;
1166 /// is_move_constructible
1167 template<typename _Tp>
1168 struct is_move_constructible
1169 : public __is_constructible_impl<_Tp, __add_rval_ref_t<_Tp>>
1171 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1172 "template argument must be a complete class or an unbounded array");
1175 /// @cond undocumented
1176 template<typename _Tp, typename... _Args>
1177 using __is_nothrow_constructible_impl
1178 = __bool_constant<__is_nothrow_constructible(_Tp, _Args...)>;
1181 /// is_nothrow_constructible
1182 template<typename _Tp, typename... _Args>
1183 struct is_nothrow_constructible
1184 : public __is_nothrow_constructible_impl<_Tp, _Args...>
1186 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1187 "template argument must be a complete class or an unbounded array");
1190 /// is_nothrow_default_constructible
1191 template<typename _Tp>
1192 struct is_nothrow_default_constructible
1193 : public __is_nothrow_constructible_impl<_Tp>
1195 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1196 "template argument must be a complete class or an unbounded array");
1199 /// is_nothrow_copy_constructible
1200 template<typename _Tp>
1201 struct is_nothrow_copy_constructible
1202 : public __is_nothrow_constructible_impl<_Tp, __add_lval_ref_t<const _Tp>>
1204 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1205 "template argument must be a complete class or an unbounded array");
1208 /// is_nothrow_move_constructible
1209 template<typename _Tp>
1210 struct is_nothrow_move_constructible
1211 : public __is_nothrow_constructible_impl<_Tp, __add_rval_ref_t<_Tp>>
1213 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1214 "template argument must be a complete class or an unbounded array");
1217 /// @cond undocumented
1218 template<typename _Tp, typename _Up>
1219 using __is_assignable_impl = __bool_constant<__is_assignable(_Tp, _Up)>;
1223 template<typename _Tp, typename _Up>
1224 struct is_assignable
1225 : public __is_assignable_impl<_Tp, _Up>
1227 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1228 "template argument must be a complete class or an unbounded array");
1231 /// is_copy_assignable
1232 template<typename _Tp>
1233 struct is_copy_assignable
1234 : public __is_assignable_impl<__add_lval_ref_t<_Tp>,
1235 __add_lval_ref_t<const _Tp>>
1237 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1238 "template argument must be a complete class or an unbounded array");
1241 /// is_move_assignable
1242 template<typename _Tp>
1243 struct is_move_assignable
1244 : public __is_assignable_impl<__add_lval_ref_t<_Tp>, __add_rval_ref_t<_Tp>>
1246 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1247 "template argument must be a complete class or an unbounded array");
1250 /// @cond undocumented
1251 template<typename _Tp, typename _Up>
1252 using __is_nothrow_assignable_impl
1253 = __bool_constant<__is_nothrow_assignable(_Tp, _Up)>;
1256 /// is_nothrow_assignable
1257 template<typename _Tp, typename _Up>
1258 struct is_nothrow_assignable
1259 : public __is_nothrow_assignable_impl<_Tp, _Up>
1261 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1262 "template argument must be a complete class or an unbounded array");
1265 /// is_nothrow_copy_assignable
1266 template<typename _Tp>
1267 struct is_nothrow_copy_assignable
1268 : public __is_nothrow_assignable_impl<__add_lval_ref_t<_Tp>,
1269 __add_lval_ref_t<const _Tp>>
1271 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1272 "template argument must be a complete class or an unbounded array");
1275 /// is_nothrow_move_assignable
1276 template<typename _Tp>
1277 struct is_nothrow_move_assignable
1278 : public __is_nothrow_assignable_impl<__add_lval_ref_t<_Tp>,
1279 __add_rval_ref_t<_Tp>>
1281 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1282 "template argument must be a complete class or an unbounded array");
1285 /// @cond undocumented
1286 template<typename _Tp, typename... _Args>
1287 using __is_trivially_constructible_impl
1288 = __bool_constant<__is_trivially_constructible(_Tp, _Args...)>;
1291 /// is_trivially_constructible
1292 template<typename _Tp, typename... _Args>
1293 struct is_trivially_constructible
1294 : public __is_trivially_constructible_impl<_Tp, _Args...>
1296 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1297 "template argument must be a complete class or an unbounded array");
1300 /// is_trivially_default_constructible
1301 template<typename _Tp>
1302 struct is_trivially_default_constructible
1303 : public __is_trivially_constructible_impl<_Tp>
1305 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1306 "template argument must be a complete class or an unbounded array");
1309#if __cpp_variable_templates && __cpp_concepts
1310 template<typename _Tp>
1311 constexpr bool __is_implicitly_default_constructible_v
1312 = requires (void(&__f)(_Tp)) { __f({}); };
1314 template<typename _Tp>
1315 struct __is_implicitly_default_constructible
1316 : __bool_constant<__is_implicitly_default_constructible_v<_Tp>>
1319 struct __do_is_implicitly_default_constructible_impl
1321 template <typename _Tp>
1322 static void __helper(const _Tp&);
1324 template <typename _Tp>
1325 static true_type __test(const _Tp&,
1326 decltype(__helper<const _Tp&>({}))* = 0);
1328 static false_type __test(...);
1331 template<typename _Tp>
1332 struct __is_implicitly_default_constructible_impl
1333 : public __do_is_implicitly_default_constructible_impl
1335 using type = decltype(__test(declval<_Tp>()));
1338 template<typename _Tp>
1339 struct __is_implicitly_default_constructible_safe
1340 : public __is_implicitly_default_constructible_impl<_Tp>::type
1343 template <typename _Tp>
1344 struct __is_implicitly_default_constructible
1345 : public __and_<__is_constructible_impl<_Tp>,
1346 __is_implicitly_default_constructible_safe<_Tp>>::type
1350 /// is_trivially_copy_constructible
1351 template<typename _Tp>
1352 struct is_trivially_copy_constructible
1353 : public __is_trivially_constructible_impl<_Tp, __add_lval_ref_t<const _Tp>>
1355 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1356 "template argument must be a complete class or an unbounded array");
1359 /// is_trivially_move_constructible
1360 template<typename _Tp>
1361 struct is_trivially_move_constructible
1362 : public __is_trivially_constructible_impl<_Tp, __add_rval_ref_t<_Tp>>
1364 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1365 "template argument must be a complete class or an unbounded array");
1368 /// @cond undocumented
1369 template<typename _Tp, typename _Up>
1370 using __is_trivially_assignable_impl
1371 = __bool_constant<__is_trivially_assignable(_Tp, _Up)>;
1374 /// is_trivially_assignable
1375 template<typename _Tp, typename _Up>
1376 struct is_trivially_assignable
1377 : public __is_trivially_assignable_impl<_Tp, _Up>
1379 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1380 "template argument must be a complete class or an unbounded array");
1383 /// is_trivially_copy_assignable
1384 template<typename _Tp>
1385 struct is_trivially_copy_assignable
1386 : public __is_trivially_assignable_impl<__add_lval_ref_t<_Tp>,
1387 __add_lval_ref_t<const _Tp>>
1389 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1390 "template argument must be a complete class or an unbounded array");
1393 /// is_trivially_move_assignable
1394 template<typename _Tp>
1395 struct is_trivially_move_assignable
1396 : public __is_trivially_assignable_impl<__add_lval_ref_t<_Tp>,
1397 __add_rval_ref_t<_Tp>>
1399 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1400 "template argument must be a complete class or an unbounded array");
1403 /// is_trivially_destructible
1404 template<typename _Tp>
1405 struct is_trivially_destructible
1406 : public __and_<__is_destructible_safe<_Tp>,
1407 __bool_constant<__has_trivial_destructor(_Tp)>>::type
1409 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1410 "template argument must be a complete class or an unbounded array");
1414 /// has_virtual_destructor
1415 template<typename _Tp>
1416 struct has_virtual_destructor
1417 : public __bool_constant<__has_virtual_destructor(_Tp)>
1419 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1420 "template argument must be a complete class or an unbounded array");
1424 // type property queries.
1427 template<typename _Tp>
1429 : public integral_constant<std::size_t, alignof(_Tp)>
1431 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
1432 "template argument must be a complete class or an unbounded array");
1438 : public integral_constant<std::size_t, 0> { };
1440 template<typename _Tp, std::size_t _Size>
1441 struct rank<_Tp[_Size]>
1442 : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1444 template<typename _Tp>
1446 : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
1449 template<typename, unsigned _Uint = 0>
1451 : public integral_constant<size_t, 0> { };
1453 template<typename _Tp, size_t _Size>
1454 struct extent<_Tp[_Size], 0>
1455 : public integral_constant<size_t, _Size> { };
1457 template<typename _Tp, unsigned _Uint, size_t _Size>
1458 struct extent<_Tp[_Size], _Uint>
1459 : public extent<_Tp, _Uint - 1>::type { };
1461 template<typename _Tp>
1462 struct extent<_Tp[], 0>
1463 : public integral_constant<size_t, 0> { };
1465 template<typename _Tp, unsigned _Uint>
1466 struct extent<_Tp[], _Uint>
1467 : public extent<_Tp, _Uint - 1>::type { };
1473#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_same)
1474 template<typename _Tp, typename _Up>
1476 : public __bool_constant<__is_same(_Tp, _Up)>
1479 template<typename _Tp, typename _Up>
1484 template<typename _Tp>
1485 struct is_same<_Tp, _Tp>
1491 template<typename _Base, typename _Derived>
1493 : public __bool_constant<__is_base_of(_Base, _Derived)>
1496#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_convertible)
1497 template<typename _From, typename _To>
1498 struct is_convertible
1499 : public __bool_constant<__is_convertible(_From, _To)>
1502 template<typename _From, typename _To,
1503 bool = __or_<is_void<_From>, is_function<_To>,
1504 is_array<_To>>::value>
1505 struct __is_convertible_helper
1507 using type = typename is_void<_To>::type;
1510#pragma GCC diagnostic push
1511#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1512 template<typename _From, typename _To>
1513 class __is_convertible_helper<_From, _To, false>
1515 template<typename _To1>
1516 static void __test_aux(_To1) noexcept;
1518 template<typename _From1, typename _To1,
1519 typename = decltype(__test_aux<_To1>(std::declval<_From1>()))>
1523 template<typename, typename>
1528 using type = decltype(__test<_From, _To>(0));
1530#pragma GCC diagnostic pop
1533 template<typename _From, typename _To>
1534 struct is_convertible
1535 : public __is_convertible_helper<_From, _To>::type
1539 // helper trait for unique_ptr<T[]>, shared_ptr<T[]>, and span<T, N>
1540 template<typename _ToElementType, typename _FromElementType>
1541 using __is_array_convertible
1542 = is_convertible<_FromElementType(*)[], _ToElementType(*)[]>;
1544#ifdef __cpp_lib_is_nothrow_convertible // C++ >= 20
1546#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_nothrow_convertible)
1547 /// is_nothrow_convertible_v
1548 template<typename _From, typename _To>
1549 inline constexpr bool is_nothrow_convertible_v
1550 = __is_nothrow_convertible(_From, _To);
1552 /// is_nothrow_convertible
1553 template<typename _From, typename _To>
1554 struct is_nothrow_convertible
1555 : public bool_constant<is_nothrow_convertible_v<_From, _To>>
1558 template<typename _From, typename _To,
1559 bool = __or_<is_void<_From>, is_function<_To>,
1560 is_array<_To>>::value>
1561 struct __is_nt_convertible_helper
1565#pragma GCC diagnostic push
1566#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
1567 template<typename _From, typename _To>
1568 class __is_nt_convertible_helper<_From, _To, false>
1570 template<typename _To1>
1571 static void __test_aux(_To1) noexcept;
1573 template<typename _From1, typename _To1>
1575 __bool_constant<noexcept(__test_aux<_To1>(std::declval<_From1>()))>
1578 template<typename, typename>
1583 using type = decltype(__test<_From, _To>(0));
1585#pragma GCC diagnostic pop
1587 /// is_nothrow_convertible
1588 template<typename _From, typename _To>
1589 struct is_nothrow_convertible
1590 : public __is_nt_convertible_helper<_From, _To>::type
1593 /// is_nothrow_convertible_v
1594 template<typename _From, typename _To>
1595 inline constexpr bool is_nothrow_convertible_v
1596 = is_nothrow_convertible<_From, _To>::value;
1598#endif // __cpp_lib_is_nothrow_convertible
1600#pragma GCC diagnostic push
1601#pragma GCC diagnostic ignored "-Wc++14-extensions" // for variable templates
1602 template<typename _Tp, typename... _Args>
1603 struct __is_nothrow_new_constructible_impl
1605 noexcept(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))
1609 template<typename _Tp, typename... _Args>
1610 _GLIBCXX17_INLINE constexpr bool __is_nothrow_new_constructible
1611 = __and_<is_constructible<_Tp, _Args...>,
1612 __is_nothrow_new_constructible_impl<_Tp, _Args...>>::value;
1613#pragma GCC diagnostic pop
1615 // Const-volatile modifications.
1618 template<typename _Tp>
1620 { using type = _Tp; };
1622 template<typename _Tp>
1623 struct remove_const<_Tp const>
1624 { using type = _Tp; };
1627 template<typename _Tp>
1628 struct remove_volatile
1629 { using type = _Tp; };
1631 template<typename _Tp>
1632 struct remove_volatile<_Tp volatile>
1633 { using type = _Tp; };
1636#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_cv)
1637 template<typename _Tp>
1639 { using type = __remove_cv(_Tp); };
1641 template<typename _Tp>
1643 { using type = _Tp; };
1645 template<typename _Tp>
1646 struct remove_cv<const _Tp>
1647 { using type = _Tp; };
1649 template<typename _Tp>
1650 struct remove_cv<volatile _Tp>
1651 { using type = _Tp; };
1653 template<typename _Tp>
1654 struct remove_cv<const volatile _Tp>
1655 { using type = _Tp; };
1659 template<typename _Tp>
1661 { using type = _Tp const; };
1664 template<typename _Tp>
1666 { using type = _Tp volatile; };
1669 template<typename _Tp>
1671 { using type = _Tp const volatile; };
1673#ifdef __cpp_lib_transformation_trait_aliases // C++ >= 14
1674 /// Alias template for remove_const
1675 template<typename _Tp>
1676 using remove_const_t = typename remove_const<_Tp>::type;
1678 /// Alias template for remove_volatile
1679 template<typename _Tp>
1680 using remove_volatile_t = typename remove_volatile<_Tp>::type;
1682 /// Alias template for remove_cv
1683 template<typename _Tp>
1684 using remove_cv_t = typename remove_cv<_Tp>::type;
1686 /// Alias template for add_const
1687 template<typename _Tp>
1688 using add_const_t = typename add_const<_Tp>::type;
1690 /// Alias template for add_volatile
1691 template<typename _Tp>
1692 using add_volatile_t = typename add_volatile<_Tp>::type;
1694 /// Alias template for add_cv
1695 template<typename _Tp>
1696 using add_cv_t = typename add_cv<_Tp>::type;
1699 // Reference transformations.
1701 /// remove_reference
1702#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_reference)
1703 template<typename _Tp>
1704 struct remove_reference
1705 { using type = __remove_reference(_Tp); };
1707 template<typename _Tp>
1708 struct remove_reference
1709 { using type = _Tp; };
1711 template<typename _Tp>
1712 struct remove_reference<_Tp&>
1713 { using type = _Tp; };
1715 template<typename _Tp>
1716 struct remove_reference<_Tp&&>
1717 { using type = _Tp; };
1720 /// add_lvalue_reference
1721 template<typename _Tp>
1722 struct add_lvalue_reference
1723 { using type = __add_lval_ref_t<_Tp>; };
1725 /// add_rvalue_reference
1726 template<typename _Tp>
1727 struct add_rvalue_reference
1728 { using type = __add_rval_ref_t<_Tp>; };
1730#if __cplusplus > 201103L
1731 /// Alias template for remove_reference
1732 template<typename _Tp>
1733 using remove_reference_t = typename remove_reference<_Tp>::type;
1735 /// Alias template for add_lvalue_reference
1736 template<typename _Tp>
1737 using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
1739 /// Alias template for add_rvalue_reference
1740 template<typename _Tp>
1741 using add_rvalue_reference_t = typename add_rvalue_reference<_Tp>::type;
1744 // Sign modifications.
1746 /// @cond undocumented
1748 // Utility for constructing identically cv-qualified types.
1749 template<typename _Unqualified, bool _IsConst, bool _IsVol>
1750 struct __cv_selector;
1752 template<typename _Unqualified>
1753 struct __cv_selector<_Unqualified, false, false>
1754 { using __type = _Unqualified; };
1756 template<typename _Unqualified>
1757 struct __cv_selector<_Unqualified, false, true>
1758 { using __type = volatile _Unqualified; };
1760 template<typename _Unqualified>
1761 struct __cv_selector<_Unqualified, true, false>
1762 { using __type = const _Unqualified; };
1764 template<typename _Unqualified>
1765 struct __cv_selector<_Unqualified, true, true>
1766 { using __type = const volatile _Unqualified; };
1768 template<typename _Qualified, typename _Unqualified,
1769 bool _IsConst = is_const<_Qualified>::value,
1770 bool _IsVol = is_volatile<_Qualified>::value>
1771 class __match_cv_qualifiers
1773 using __match = __cv_selector<_Unqualified, _IsConst, _IsVol>;
1776 using __type = typename __match::__type;
1779 // Utility for finding the unsigned versions of signed integral types.
1780 template<typename _Tp>
1781 struct __make_unsigned
1782 { using __type = _Tp; };
1785 struct __make_unsigned<char>
1786 { using __type = unsigned char; };
1789 struct __make_unsigned<signed char>
1790 { using __type = unsigned char; };
1793 struct __make_unsigned<short>
1794 { using __type = unsigned short; };
1797 struct __make_unsigned<int>
1798 { using __type = unsigned int; };
1801 struct __make_unsigned<long>
1802 { using __type = unsigned long; };
1805 struct __make_unsigned<long long>
1806 { using __type = unsigned long long; };
1808#if defined(__GLIBCXX_TYPE_INT_N_0)
1811 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_0>
1812 { using __type = unsigned __GLIBCXX_TYPE_INT_N_0; };
1814#if defined(__GLIBCXX_TYPE_INT_N_1)
1817 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_1>
1818 { using __type = unsigned __GLIBCXX_TYPE_INT_N_1; };
1820#if defined(__GLIBCXX_TYPE_INT_N_2)
1823 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_2>
1824 { using __type = unsigned __GLIBCXX_TYPE_INT_N_2; };
1826#if defined(__GLIBCXX_TYPE_INT_N_3)
1829 struct __make_unsigned<__GLIBCXX_TYPE_INT_N_3>
1830 { using __type = unsigned __GLIBCXX_TYPE_INT_N_3; };
1833 // Select between integral and enum: not possible to be both.
1834 template<typename _Tp,
1835 bool _IsInt = is_integral<_Tp>::value,
1836 bool _IsEnum = __is_enum(_Tp)>
1837 class __make_unsigned_selector;
1839 template<typename _Tp>
1840 class __make_unsigned_selector<_Tp, true, false>
1842 using __unsigned_type
1843 = typename __make_unsigned<__remove_cv_t<_Tp>>::__type;
1847 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1850 class __make_unsigned_selector_base
1853 template<typename...> struct _List { };
1855 template<typename _Tp, typename... _Up>
1856 struct _List<_Tp, _Up...> : _List<_Up...>
1857 { static constexpr size_t __size = sizeof(_Tp); };
1859 template<size_t _Sz, typename _Tp, bool = (_Sz <= _Tp::__size)>
1862 template<size_t _Sz, typename _Uint, typename... _UInts>
1863 struct __select<_Sz, _List<_Uint, _UInts...>, true>
1864 { using __type = _Uint; };
1866 template<size_t _Sz, typename _Uint, typename... _UInts>
1867 struct __select<_Sz, _List<_Uint, _UInts...>, false>
1868 : __select<_Sz, _List<_UInts...>>
1872 // Choose unsigned integer type with the smallest rank and same size as _Tp
1873 template<typename _Tp>
1874 class __make_unsigned_selector<_Tp, false, true>
1875 : __make_unsigned_selector_base
1877 // With -fshort-enums, an enum may be as small as a char.
1878 using _UInts = _List<unsigned char, unsigned short, unsigned int,
1879 unsigned long, unsigned long long>;
1881 using __unsigned_type = typename __select<sizeof(_Tp), _UInts>::__type;
1885 = typename __match_cv_qualifiers<_Tp, __unsigned_type>::__type;
1888 // wchar_t, char8_t, char16_t and char32_t are integral types but are
1889 // neither signed integer types nor unsigned integer types, so must be
1890 // transformed to the unsigned integer type with the smallest rank.
1891 // Use the partial specialization for enumeration types to do that.
1893 struct __make_unsigned<wchar_t>
1896 = typename __make_unsigned_selector<wchar_t, false, true>::__type;
1899#ifdef _GLIBCXX_USE_CHAR8_T
1901 struct __make_unsigned<char8_t>
1904 = typename __make_unsigned_selector<char8_t, false, true>::__type;
1909 struct __make_unsigned<char16_t>
1912 = typename __make_unsigned_selector<char16_t, false, true>::__type;
1916 struct __make_unsigned<char32_t>
1919 = typename __make_unsigned_selector<char32_t, false, true>::__type;
1923 // Given an integral/enum type, return the corresponding unsigned
1925 // Primary template.
1927 template<typename _Tp>
1928 struct make_unsigned
1929 { using type = typename __make_unsigned_selector<_Tp>::__type; };
1931 // Integral, but don't define.
1932 template<> struct make_unsigned<bool>;
1933 template<> struct make_unsigned<bool const>;
1934 template<> struct make_unsigned<bool volatile>;
1935 template<> struct make_unsigned<bool const volatile>;
1937 /// @cond undocumented
1939 // Utility for finding the signed versions of unsigned integral types.
1940 template<typename _Tp>
1941 struct __make_signed
1942 { using __type = _Tp; };
1945 struct __make_signed<char>
1946 { using __type = signed char; };
1949 struct __make_signed<unsigned char>
1950 { using __type = signed char; };
1953 struct __make_signed<unsigned short>
1954 { using __type = signed short; };
1957 struct __make_signed<unsigned int>
1958 { using __type = signed int; };
1961 struct __make_signed<unsigned long>
1962 { using __type = signed long; };
1965 struct __make_signed<unsigned long long>
1966 { using __type = signed long long; };
1968#if defined(__GLIBCXX_TYPE_INT_N_0)
1971 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_0>
1972 { using __type = __GLIBCXX_TYPE_INT_N_0; };
1974#if defined(__GLIBCXX_TYPE_INT_N_1)
1977 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_1>
1978 { using __type = __GLIBCXX_TYPE_INT_N_1; };
1980#if defined(__GLIBCXX_TYPE_INT_N_2)
1983 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_2>
1984 { using __type = __GLIBCXX_TYPE_INT_N_2; };
1986#if defined(__GLIBCXX_TYPE_INT_N_3)
1989 struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_3>
1990 { using __type = __GLIBCXX_TYPE_INT_N_3; };
1993 // Select between integral and enum: not possible to be both.
1994 template<typename _Tp,
1995 bool _IsInt = is_integral<_Tp>::value,
1996 bool _IsEnum = __is_enum(_Tp)>
1997 class __make_signed_selector;
1999 template<typename _Tp>
2000 class __make_signed_selector<_Tp, true, false>
2003 = typename __make_signed<__remove_cv_t<_Tp>>::__type;
2007 = typename __match_cv_qualifiers<_Tp, __signed_type>::__type;
2010 // Choose signed integer type with the smallest rank and same size as _Tp
2011 template<typename _Tp>
2012 class __make_signed_selector<_Tp, false, true>
2014 using __unsigned_type = typename __make_unsigned_selector<_Tp>::__type;
2017 using __type = typename __make_signed_selector<__unsigned_type>::__type;
2020 // wchar_t, char16_t and char32_t are integral types but are neither
2021 // signed integer types nor unsigned integer types, so must be
2022 // transformed to the signed integer type with the smallest rank.
2023 // Use the partial specialization for enumeration types to do that.
2025 struct __make_signed<wchar_t>
2028 = typename __make_signed_selector<wchar_t, false, true>::__type;
2031#if defined(_GLIBCXX_USE_CHAR8_T)
2033 struct __make_signed<char8_t>
2036 = typename __make_signed_selector<char8_t, false, true>::__type;
2041 struct __make_signed<char16_t>
2044 = typename __make_signed_selector<char16_t, false, true>::__type;
2048 struct __make_signed<char32_t>
2051 = typename __make_signed_selector<char32_t, false, true>::__type;
2055 // Given an integral/enum type, return the corresponding signed
2057 // Primary template.
2059 template<typename _Tp>
2061 { using type = typename __make_signed_selector<_Tp>::__type; };
2063 // Integral, but don't define.
2064 template<> struct make_signed<bool>;
2065 template<> struct make_signed<bool const>;
2066 template<> struct make_signed<bool volatile>;
2067 template<> struct make_signed<bool const volatile>;
2069#if __cplusplus > 201103L
2070 /// Alias template for make_signed
2071 template<typename _Tp>
2072 using make_signed_t = typename make_signed<_Tp>::type;
2074 /// Alias template for make_unsigned
2075 template<typename _Tp>
2076 using make_unsigned_t = typename make_unsigned<_Tp>::type;
2079 // Array modifications.
2082 template<typename _Tp>
2083 struct remove_extent
2084 { using type = _Tp; };
2086 template<typename _Tp, std::size_t _Size>
2087 struct remove_extent<_Tp[_Size]>
2088 { using type = _Tp; };
2090 template<typename _Tp>
2091 struct remove_extent<_Tp[]>
2092 { using type = _Tp; };
2094 /// remove_all_extents
2095 template<typename _Tp>
2096 struct remove_all_extents
2097 { using type = _Tp; };
2099 template<typename _Tp, std::size_t _Size>
2100 struct remove_all_extents<_Tp[_Size]>
2101 { using type = typename remove_all_extents<_Tp>::type; };
2103 template<typename _Tp>
2104 struct remove_all_extents<_Tp[]>
2105 { using type = typename remove_all_extents<_Tp>::type; };
2107#if __cplusplus > 201103L
2108 /// Alias template for remove_extent
2109 template<typename _Tp>
2110 using remove_extent_t = typename remove_extent<_Tp>::type;
2112 /// Alias template for remove_all_extents
2113 template<typename _Tp>
2114 using remove_all_extents_t = typename remove_all_extents<_Tp>::type;
2117 // Pointer modifications.
2120#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_pointer)
2121 template<typename _Tp>
2122 struct remove_pointer
2123 { using type = __remove_pointer(_Tp); };
2125 template<typename _Tp, typename>
2126 struct __remove_pointer_helper
2127 { using type = _Tp; };
2129 template<typename _Tp, typename _Up>
2130 struct __remove_pointer_helper<_Tp, _Up*>
2131 { using type = _Up; };
2133 template<typename _Tp>
2134 struct remove_pointer
2135 : public __remove_pointer_helper<_Tp, __remove_cv_t<_Tp>>
2139 template<typename _Tp, typename = void>
2140 struct __add_pointer_helper
2141 { using type = _Tp; };
2143 template<typename _Tp>
2144 struct __add_pointer_helper<_Tp, __void_t<_Tp*>>
2145 { using type = _Tp*; };
2148 template<typename _Tp>
2150 : public __add_pointer_helper<_Tp>
2153 template<typename _Tp>
2154 struct add_pointer<_Tp&>
2155 { using type = _Tp*; };
2157 template<typename _Tp>
2158 struct add_pointer<_Tp&&>
2159 { using type = _Tp*; };
2161#if __cplusplus > 201103L
2162 /// Alias template for remove_pointer
2163 template<typename _Tp>
2164 using remove_pointer_t = typename remove_pointer<_Tp>::type;
2166 /// Alias template for add_pointer
2167 template<typename _Tp>
2168 using add_pointer_t = typename add_pointer<_Tp>::type;
2171 template<std::size_t _Len>
2172 struct __aligned_storage_msa
2176 unsigned char __data[_Len];
2177 struct __attribute__((__aligned__)) { } __align;
2182 * @brief Alignment type.
2184 * The value of _Align is a default-alignment which shall be the
2185 * most stringent alignment requirement for any C++ object type
2186 * whose size is no greater than _Len (3.9). The member typedef
2187 * type shall be a POD type suitable for use as uninitialized
2188 * storage for any object whose size is at most _Len and whose
2189 * alignment is a divisor of _Align.
2191 * @deprecated Deprecated in C++23. Uses can be replaced by an
2192 * array std::byte[_Len] declared with alignas(_Align).
2194 template<std::size_t _Len, std::size_t _Align =
2195 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2197 _GLIBCXX23_DEPRECATED
2202 unsigned char __data[_Len];
2203 struct __attribute__((__aligned__((_Align)))) { } __align;
2207 template <typename... _Types>
2208 struct __strictest_alignment
2210 static const size_t _S_alignment = 0;
2211 static const size_t _S_size = 0;
2214 template <typename _Tp, typename... _Types>
2215 struct __strictest_alignment<_Tp, _Types...>
2217 static const size_t _S_alignment =
2218 alignof(_Tp) > __strictest_alignment<_Types...>::_S_alignment
2219 ? alignof(_Tp) : __strictest_alignment<_Types...>::_S_alignment;
2220 static const size_t _S_size =
2221 sizeof(_Tp) > __strictest_alignment<_Types...>::_S_size
2222 ? sizeof(_Tp) : __strictest_alignment<_Types...>::_S_size;
2225#pragma GCC diagnostic push
2226#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
2229 * @brief Provide aligned storage for types.
2231 * [meta.trans.other]
2233 * Provides aligned storage for any of the provided types of at
2236 * @see aligned_storage
2238 * @deprecated Deprecated in C++23.
2240 template <size_t _Len, typename... _Types>
2242 _GLIBCXX23_DEPRECATED
2246 static_assert(sizeof...(_Types) != 0, "At least one type is required");
2248 using __strictest = __strictest_alignment<_Types...>;
2249 static const size_t _S_len = _Len > __strictest::_S_size
2250 ? _Len : __strictest::_S_size;
2252 /// The value of the strictest alignment of _Types.
2253 static const size_t alignment_value = __strictest::_S_alignment;
2255 using type = typename aligned_storage<_S_len, alignment_value>::type;
2258 template <size_t _Len, typename... _Types>
2259 const size_t aligned_union<_Len, _Types...>::alignment_value;
2260#pragma GCC diagnostic pop
2262 /// @cond undocumented
2264 // Decay trait for arrays and functions, used for perfect forwarding
2265 // in make_pair, make_tuple, etc.
2266 template<typename _Up>
2267 struct __decay_selector
2268 : __conditional_t<is_const<const _Up>::value, // false for functions
2269 remove_cv<_Up>, // N.B. DR 705.
2270 add_pointer<_Up>> // function decays to pointer
2273 template<typename _Up, size_t _Nm>
2274 struct __decay_selector<_Up[_Nm]>
2275 { using type = _Up*; };
2277 template<typename _Up>
2278 struct __decay_selector<_Up[]>
2279 { using type = _Up*; };
2284 template<typename _Tp>
2286 { using type = typename __decay_selector<_Tp>::type; };
2288 template<typename _Tp>
2290 { using type = typename __decay_selector<_Tp>::type; };
2292 template<typename _Tp>
2294 { using type = typename __decay_selector<_Tp>::type; };
2296 /// @cond undocumented
2298 // Helper which adds a reference to a type when given a reference_wrapper
2299 template<typename _Tp>
2300 struct __strip_reference_wrapper
2305 template<typename _Tp>
2306 struct __strip_reference_wrapper<reference_wrapper<_Tp> >
2308 using __type = _Tp&;
2311 // __decay_t (std::decay_t for C++11).
2312 template<typename _Tp>
2313 using __decay_t = typename decay<_Tp>::type;
2315 template<typename _Tp>
2316 using __decay_and_strip = __strip_reference_wrapper<__decay_t<_Tp>>;
2319 /// @cond undocumented
2321 // Helper for SFINAE constraints
2322 template<typename... _Cond>
2323 using _Require = __enable_if_t<__and_<_Cond...>::value>;
2325 // __remove_cvref_t (std::remove_cvref_t for C++11).
2326 template<typename _Tp>
2327 using __remove_cvref_t
2328 = typename remove_cv<typename remove_reference<_Tp>::type>::type;
2331 // Primary template.
2332 /// Define a member typedef @c type to one of two argument types.
2333 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2335 { using type = _Iftrue; };
2337 // Partial specialization for false.
2338 template<typename _Iftrue, typename _Iffalse>
2339 struct conditional<false, _Iftrue, _Iffalse>
2340 { using type = _Iffalse; };
2343 template<typename... _Tp>
2346 // Sfinae-friendly common_type implementation:
2348 /// @cond undocumented
2350 // For several sfinae-friendly trait implementations we transport both the
2351 // result information (as the member type) and the failure information (no
2352 // member type). This is very similar to std::enable_if, but we cannot use
2353 // that, because we need to derive from them as an implementation detail.
2355 template<typename _Tp>
2356 struct __success_type
2357 { using type = _Tp; };
2359 struct __failure_type
2362 struct __do_common_type_impl
2364 template<typename _Tp, typename _Up>
2366 = decltype(true ? std::declval<_Tp>() : std::declval<_Up>());
2368 // if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2369 // denotes a valid type, let C denote that type.
2370 template<typename _Tp, typename _Up>
2371 static __success_type<__decay_t<__cond_t<_Tp, _Up>>>
2374#if __cplusplus > 201703L
2375 // Otherwise, if COND-RES(CREF(D1), CREF(D2)) denotes a type,
2376 // let C denote the type decay_t<COND-RES(CREF(D1), CREF(D2))>.
2377 template<typename _Tp, typename _Up>
2378 static __success_type<__remove_cvref_t<__cond_t<const _Tp&, const _Up&>>>
2382 template<typename, typename>
2383 static __failure_type
2386 template<typename _Tp, typename _Up>
2387 static decltype(_S_test_2<_Tp, _Up>(0))
2391 // If sizeof...(T) is zero, there shall be no member type.
2393 struct common_type<>
2396 // If sizeof...(T) is one, the same type, if any, as common_type_t<T0, T0>.
2397 template<typename _Tp0>
2398 struct common_type<_Tp0>
2399 : public common_type<_Tp0, _Tp0>
2402 // If sizeof...(T) is two, ...
2403 template<typename _Tp1, typename _Tp2,
2404 typename _Dp1 = __decay_t<_Tp1>, typename _Dp2 = __decay_t<_Tp2>>
2405 struct __common_type_impl
2407 // If is_same_v<T1, D1> is false or is_same_v<T2, D2> is false,
2408 // let C denote the same type, if any, as common_type_t<D1, D2>.
2409 using type = common_type<_Dp1, _Dp2>;
2412 template<typename _Tp1, typename _Tp2>
2413 struct __common_type_impl<_Tp1, _Tp2, _Tp1, _Tp2>
2414 : private __do_common_type_impl
2416 // Otherwise, if decay_t<decltype(false ? declval<D1>() : declval<D2>())>
2417 // denotes a valid type, let C denote that type.
2418 using type = decltype(_S_test<_Tp1, _Tp2>(0));
2421 // If sizeof...(T) is two, ...
2422 template<typename _Tp1, typename _Tp2>
2423 struct common_type<_Tp1, _Tp2>
2424 : public __common_type_impl<_Tp1, _Tp2>::type
2427 template<typename...>
2428 struct __common_type_pack
2431 template<typename, typename, typename = void>
2432 struct __common_type_fold;
2434 // If sizeof...(T) is greater than two, ...
2435 template<typename _Tp1, typename _Tp2, typename... _Rp>
2436 struct common_type<_Tp1, _Tp2, _Rp...>
2437 : public __common_type_fold<common_type<_Tp1, _Tp2>,
2438 __common_type_pack<_Rp...>>
2441 // Let C denote the same type, if any, as common_type_t<T1, T2>.
2442 // If there is such a type C, type shall denote the same type, if any,
2443 // as common_type_t<C, R...>.
2444 template<typename _CTp, typename... _Rp>
2445 struct __common_type_fold<_CTp, __common_type_pack<_Rp...>,
2446 __void_t<typename _CTp::type>>
2447 : public common_type<typename _CTp::type, _Rp...>
2450 // Otherwise, there shall be no member type.
2451 template<typename _CTp, typename _Rp>
2452 struct __common_type_fold<_CTp, _Rp, void>
2455 template<typename _Tp, bool = __is_enum(_Tp)>
2456 struct __underlying_type_impl
2458 using type = __underlying_type(_Tp);
2461 template<typename _Tp>
2462 struct __underlying_type_impl<_Tp, false>
2466 /// The underlying type of an enum.
2467 template<typename _Tp>
2468 struct underlying_type
2469 : public __underlying_type_impl<_Tp>
2472 /// @cond undocumented
2473 template<typename _Tp>
2474 struct __declval_protector
2476 static const bool __stop = false;
2480 /** Utility to simplify expressions used in unevaluated operands
2482 * @ingroup utilities
2484 template<typename _Tp>
2485 auto declval() noexcept -> decltype(__declval<_Tp>(0))
2487 static_assert(__declval_protector<_Tp>::__stop,
2488 "declval() must not be used!");
2489 return __declval<_Tp>(0);
2493 template<typename _Signature>
2496 // Sfinae-friendly result_of implementation:
2498 /// @cond undocumented
2499 struct __invoke_memfun_ref { };
2500 struct __invoke_memfun_deref { };
2501 struct __invoke_memobj_ref { };
2502 struct __invoke_memobj_deref { };
2503 struct __invoke_other { };
2505 // Associate a tag type with a specialization of __success_type.
2506 template<typename _Tp, typename _Tag>
2507 struct __result_of_success : __success_type<_Tp>
2508 { using __invoke_type = _Tag; };
2510 // [func.require] paragraph 1 bullet 1:
2511 struct __result_of_memfun_ref_impl
2513 template<typename _Fp, typename _Tp1, typename... _Args>
2514 static __result_of_success<decltype(
2515 (std::declval<_Tp1>().*std::declval<_Fp>())(std::declval<_Args>()...)
2516 ), __invoke_memfun_ref> _S_test(int);
2518 template<typename...>
2519 static __failure_type _S_test(...);
2522 template<typename _MemPtr, typename _Arg, typename... _Args>
2523 struct __result_of_memfun_ref
2524 : private __result_of_memfun_ref_impl
2526 using type = decltype(_S_test<_MemPtr, _Arg, _Args...>(0));
2529 // [func.require] paragraph 1 bullet 2:
2530 struct __result_of_memfun_deref_impl
2532 template<typename _Fp, typename _Tp1, typename... _Args>
2533 static __result_of_success<decltype(
2534 ((*std::declval<_Tp1>()).*std::declval<_Fp>())(std::declval<_Args>()...)
2535 ), __invoke_memfun_deref> _S_test(int);
2537 template<typename...>
2538 static __failure_type _S_test(...);
2541 template<typename _MemPtr, typename _Arg, typename... _Args>
2542 struct __result_of_memfun_deref
2543 : private __result_of_memfun_deref_impl
2545 using type = decltype(_S_test<_MemPtr, _Arg, _Args...>(0));
2548 // [func.require] paragraph 1 bullet 3:
2549 struct __result_of_memobj_ref_impl
2551 template<typename _Fp, typename _Tp1>
2552 static __result_of_success<decltype(
2553 std::declval<_Tp1>().*std::declval<_Fp>()
2554 ), __invoke_memobj_ref> _S_test(int);
2556 template<typename, typename>
2557 static __failure_type _S_test(...);
2560 template<typename _MemPtr, typename _Arg>
2561 struct __result_of_memobj_ref
2562 : private __result_of_memobj_ref_impl
2564 using type = decltype(_S_test<_MemPtr, _Arg>(0));
2567 // [func.require] paragraph 1 bullet 4:
2568 struct __result_of_memobj_deref_impl
2570 template<typename _Fp, typename _Tp1>
2571 static __result_of_success<decltype(
2572 (*std::declval<_Tp1>()).*std::declval<_Fp>()
2573 ), __invoke_memobj_deref> _S_test(int);
2575 template<typename, typename>
2576 static __failure_type _S_test(...);
2579 template<typename _MemPtr, typename _Arg>
2580 struct __result_of_memobj_deref
2581 : private __result_of_memobj_deref_impl
2583 using type = decltype(_S_test<_MemPtr, _Arg>(0));
2586 template<typename _MemPtr, typename _Arg>
2587 struct __result_of_memobj;
2589 template<typename _Res, typename _Class, typename _Arg>
2590 struct __result_of_memobj<_Res _Class::*, _Arg>
2592 using _Argval = __remove_cvref_t<_Arg>;
2593 using _MemPtr = _Res _Class::*;
2594 using type = typename __conditional_t<__or_<is_same<_Argval, _Class>,
2595 is_base_of<_Class, _Argval>>::value,
2596 __result_of_memobj_ref<_MemPtr, _Arg>,
2597 __result_of_memobj_deref<_MemPtr, _Arg>
2601 template<typename _MemPtr, typename _Arg, typename... _Args>
2602 struct __result_of_memfun;
2604 template<typename _Res, typename _Class, typename _Arg, typename... _Args>
2605 struct __result_of_memfun<_Res _Class::*, _Arg, _Args...>
2607 using _Argval = typename remove_reference<_Arg>::type;
2608 using _MemPtr = _Res _Class::*;
2609 using type = typename __conditional_t<is_base_of<_Class, _Argval>::value,
2610 __result_of_memfun_ref<_MemPtr, _Arg, _Args...>,
2611 __result_of_memfun_deref<_MemPtr, _Arg, _Args...>
2615 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2616 // 2219. INVOKE-ing a pointer to member with a reference_wrapper
2617 // as the object expression
2619 // Used by result_of, invoke etc. to unwrap a reference_wrapper.
2620 template<typename _Tp, typename _Up = __remove_cvref_t<_Tp>>
2626 template<typename _Tp, typename _Up>
2627 struct __inv_unwrap<_Tp, reference_wrapper<_Up>>
2632 template<bool, bool, typename _Functor, typename... _ArgTypes>
2633 struct __result_of_impl
2635 using type = __failure_type;
2638 template<typename _MemPtr, typename _Arg>
2639 struct __result_of_impl<true, false, _MemPtr, _Arg>
2640 : public __result_of_memobj<__decay_t<_MemPtr>,
2641 typename __inv_unwrap<_Arg>::type>
2644 template<typename _MemPtr, typename _Arg, typename... _Args>
2645 struct __result_of_impl<false, true, _MemPtr, _Arg, _Args...>
2646 : public __result_of_memfun<__decay_t<_MemPtr>,
2647 typename __inv_unwrap<_Arg>::type, _Args...>
2650 // [func.require] paragraph 1 bullet 5:
2651 struct __result_of_other_impl
2653 template<typename _Fn, typename... _Args>
2654 static __result_of_success<decltype(
2655 std::declval<_Fn>()(std::declval<_Args>()...)
2656 ), __invoke_other> _S_test(int);
2658 template<typename...>
2659 static __failure_type _S_test(...);
2662 template<typename _Functor, typename... _ArgTypes>
2663 struct __result_of_impl<false, false, _Functor, _ArgTypes...>
2664 : private __result_of_other_impl
2666 using type = decltype(_S_test<_Functor, _ArgTypes...>(0));
2669 // __invoke_result (std::invoke_result for C++11)
2670 template<typename _Functor, typename... _ArgTypes>
2671 struct __invoke_result
2672 : public __result_of_impl<
2673 is_member_object_pointer<
2674 typename remove_reference<_Functor>::type
2676 is_member_function_pointer<
2677 typename remove_reference<_Functor>::type
2679 _Functor, _ArgTypes...
2683 // __invoke_result_t (std::invoke_result_t for C++11)
2684 template<typename _Fn, typename... _Args>
2685 using __invoke_result_t = typename __invoke_result<_Fn, _Args...>::type;
2688 template<typename _Functor, typename... _ArgTypes>
2689 struct result_of<_Functor(_ArgTypes...)>
2690 : public __invoke_result<_Functor, _ArgTypes...>
2691 { } _GLIBCXX17_DEPRECATED_SUGGEST("std::invoke_result");
2693#if __cplusplus >= 201402L
2694#pragma GCC diagnostic push
2695#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
2696 /// Alias template for aligned_storage
2697 template<size_t _Len, size_t _Align =
2698 __alignof__(typename __aligned_storage_msa<_Len>::__type)>
2699 using aligned_storage_t _GLIBCXX23_DEPRECATED = typename aligned_storage<_Len, _Align>::type;
2701 template <size_t _Len, typename... _Types>
2702 using aligned_union_t _GLIBCXX23_DEPRECATED = typename aligned_union<_Len, _Types...>::type;
2703#pragma GCC diagnostic pop
2705 /// Alias template for decay
2706 template<typename _Tp>
2707 using decay_t = typename decay<_Tp>::type;
2709 /// Alias template for enable_if
2710 template<bool _Cond, typename _Tp = void>
2711 using enable_if_t = typename enable_if<_Cond, _Tp>::type;
2713 /// Alias template for conditional
2714 template<bool _Cond, typename _Iftrue, typename _Iffalse>
2715 using conditional_t = typename conditional<_Cond, _Iftrue, _Iffalse>::type;
2717 /// Alias template for common_type
2718 template<typename... _Tp>
2719 using common_type_t = typename common_type<_Tp...>::type;
2721 /// Alias template for underlying_type
2722 template<typename _Tp>
2723 using underlying_type_t = typename underlying_type<_Tp>::type;
2725 /// Alias template for result_of
2726 template<typename _Tp>
2727 using result_of_t = typename result_of<_Tp>::type;
2730#ifdef __cpp_lib_void_t // C++ >= 17 || GNU++ >= 11
2731 /// A metafunction that always yields void, used for detecting valid types.
2732 template<typename...> using void_t = void;
2735 /// @cond undocumented
2738 // Detect whether _Op<_Args...> is a valid type, use default _Def if not.
2741 // Implementation of the detection idiom (negative case).
2742 template<typename _Def, template<typename...> class _Op, typename... _Args>
2743 struct __detected_or
2746 using __is_detected = false_type;
2749 // Implementation of the detection idiom (positive case).
2750 template<typename _Def, template<typename...> class _Op, typename... _Args>
2751 requires requires { typename _Op<_Args...>; }
2752 struct __detected_or<_Def, _Op, _Args...>
2754 using type = _Op<_Args...>;
2755 using __is_detected = true_type;
2758 /// Implementation of the detection idiom (negative case).
2759 template<typename _Default, typename _AlwaysVoid,
2760 template<typename...> class _Op, typename... _Args>
2763 using type = _Default;
2764 using __is_detected = false_type;
2767 /// Implementation of the detection idiom (positive case).
2768 template<typename _Default, template<typename...> class _Op,
2770 struct __detector<_Default, __void_t<_Op<_Args...>>, _Op, _Args...>
2772 using type = _Op<_Args...>;
2773 using __is_detected = true_type;
2776 template<typename _Default, template<typename...> class _Op,
2778 using __detected_or = __detector<_Default, void, _Op, _Args...>;
2779#endif // __cpp_concepts
2781 // _Op<_Args...> if that is a valid type, otherwise _Default.
2782 template<typename _Default, template<typename...> class _Op,
2784 using __detected_or_t
2785 = typename __detected_or<_Default, _Op, _Args...>::type;
2788 * Use SFINAE to determine if the type _Tp has a publicly-accessible
2789 * member type _NTYPE.
2791#define _GLIBCXX_HAS_NESTED_TYPE(_NTYPE) \
2792 template<typename _Tp, typename = __void_t<>> \
2793 struct __has_##_NTYPE \
2796 template<typename _Tp> \
2797 struct __has_##_NTYPE<_Tp, __void_t<typename _Tp::_NTYPE>> \
2801 template <typename _Tp>
2802 struct __is_swappable;
2804 template <typename _Tp>
2805 struct __is_nothrow_swappable;
2808 struct __is_tuple_like_impl : false_type
2811 // Internal type trait that allows us to sfinae-protect tuple_cat.
2812 template<typename _Tp>
2813 struct __is_tuple_like
2814 : public __is_tuple_like_impl<__remove_cvref_t<_Tp>>::type
2818 template<typename _Tp>
2819 _GLIBCXX20_CONSTEXPR
2821 _Require<__not_<__is_tuple_like<_Tp>>,
2822 is_move_constructible<_Tp>,
2823 is_move_assignable<_Tp>>
2825 noexcept(__and_<is_nothrow_move_constructible<_Tp>,
2826 is_nothrow_move_assignable<_Tp>>::value);
2828 template<typename _Tp, size_t _Nm>
2829 _GLIBCXX20_CONSTEXPR
2831 __enable_if_t<__is_swappable<_Tp>::value>
2832 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
2833 noexcept(__is_nothrow_swappable<_Tp>::value);
2835 /// @cond undocumented
2836 namespace __swappable_details {
2839 struct __do_is_swappable_impl
2841 template<typename _Tp, typename
2842 = decltype(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))>
2843 static true_type __test(int);
2846 static false_type __test(...);
2849 struct __do_is_nothrow_swappable_impl
2851 template<typename _Tp>
2852 static __bool_constant<
2853 noexcept(swap(std::declval<_Tp&>(), std::declval<_Tp&>()))
2857 static false_type __test(...);
2860 } // namespace __swappable_details
2862 template<typename _Tp>
2863 struct __is_swappable_impl
2864 : public __swappable_details::__do_is_swappable_impl
2866 using type = decltype(__test<_Tp>(0));
2869 template<typename _Tp>
2870 struct __is_nothrow_swappable_impl
2871 : public __swappable_details::__do_is_nothrow_swappable_impl
2873 using type = decltype(__test<_Tp>(0));
2876 template<typename _Tp>
2877 struct __is_swappable
2878 : public __is_swappable_impl<_Tp>::type
2881 template<typename _Tp>
2882 struct __is_nothrow_swappable
2883 : public __is_nothrow_swappable_impl<_Tp>::type
2887#ifdef __cpp_lib_is_swappable // C++ >= 17 || GNU++ >= 11
2888 /// Metafunctions used for detecting swappable types: p0185r1
2891 template<typename _Tp>
2893 : public __is_swappable_impl<_Tp>::type
2895 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2896 "template argument must be a complete class or an unbounded array");
2899 /// is_nothrow_swappable
2900 template<typename _Tp>
2901 struct is_nothrow_swappable
2902 : public __is_nothrow_swappable_impl<_Tp>::type
2904 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2905 "template argument must be a complete class or an unbounded array");
2908#if __cplusplus >= 201402L
2910 template<typename _Tp>
2911 _GLIBCXX17_INLINE constexpr bool is_swappable_v =
2912 is_swappable<_Tp>::value;
2914 /// is_nothrow_swappable_v
2915 template<typename _Tp>
2916 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_v =
2917 is_nothrow_swappable<_Tp>::value;
2918#endif // __cplusplus >= 201402L
2920 /// @cond undocumented
2921 namespace __swappable_with_details {
2924 struct __do_is_swappable_with_impl
2926 template<typename _Tp, typename _Up, typename
2927 = decltype(swap(std::declval<_Tp>(), std::declval<_Up>())),
2929 = decltype(swap(std::declval<_Up>(), std::declval<_Tp>()))>
2930 static true_type __test(int);
2932 template<typename, typename>
2933 static false_type __test(...);
2936 struct __do_is_nothrow_swappable_with_impl
2938 template<typename _Tp, typename _Up>
2939 static __bool_constant<
2940 noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()))
2942 noexcept(swap(std::declval<_Up>(), std::declval<_Tp>()))
2945 template<typename, typename>
2946 static false_type __test(...);
2949 } // namespace __swappable_with_details
2951 template<typename _Tp, typename _Up>
2952 struct __is_swappable_with_impl
2953 : public __swappable_with_details::__do_is_swappable_with_impl
2955 using type = decltype(__test<_Tp, _Up>(0));
2958 // Optimization for the homogenous lvalue case, not required:
2959 template<typename _Tp>
2960 struct __is_swappable_with_impl<_Tp&, _Tp&>
2961 : public __swappable_details::__do_is_swappable_impl
2963 using type = decltype(__test<_Tp&>(0));
2966 template<typename _Tp, typename _Up>
2967 struct __is_nothrow_swappable_with_impl
2968 : public __swappable_with_details::__do_is_nothrow_swappable_with_impl
2970 using type = decltype(__test<_Tp, _Up>(0));
2973 // Optimization for the homogenous lvalue case, not required:
2974 template<typename _Tp>
2975 struct __is_nothrow_swappable_with_impl<_Tp&, _Tp&>
2976 : public __swappable_details::__do_is_nothrow_swappable_impl
2978 using type = decltype(__test<_Tp&>(0));
2982 /// is_swappable_with
2983 template<typename _Tp, typename _Up>
2984 struct is_swappable_with
2985 : public __is_swappable_with_impl<_Tp, _Up>::type
2987 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2988 "first template argument must be a complete class or an unbounded array");
2989 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
2990 "second template argument must be a complete class or an unbounded array");
2993 /// is_nothrow_swappable_with
2994 template<typename _Tp, typename _Up>
2995 struct is_nothrow_swappable_with
2996 : public __is_nothrow_swappable_with_impl<_Tp, _Up>::type
2998 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
2999 "first template argument must be a complete class or an unbounded array");
3000 static_assert(std::__is_complete_or_unbounded(__type_identity<_Up>{}),
3001 "second template argument must be a complete class or an unbounded array");
3004#if __cplusplus >= 201402L
3005 /// is_swappable_with_v
3006 template<typename _Tp, typename _Up>
3007 _GLIBCXX17_INLINE constexpr bool is_swappable_with_v =
3008 is_swappable_with<_Tp, _Up>::value;
3010 /// is_nothrow_swappable_with_v
3011 template<typename _Tp, typename _Up>
3012 _GLIBCXX17_INLINE constexpr bool is_nothrow_swappable_with_v =
3013 is_nothrow_swappable_with<_Tp, _Up>::value;
3014#endif // __cplusplus >= 201402L
3016#endif // __cpp_lib_is_swappable
3018 /// @cond undocumented
3020 // __is_invocable (std::is_invocable for C++11)
3022 // The primary template is used for invalid INVOKE expressions.
3023 template<typename _Result, typename _Ret,
3024 bool = is_void<_Ret>::value, typename = void>
3025 struct __is_invocable_impl
3028 using __nothrow_conv = false_type; // For is_nothrow_invocable_r
3031 // Used for valid INVOKE and INVOKE<void> expressions.
3032 template<typename _Result, typename _Ret>
3033 struct __is_invocable_impl<_Result, _Ret,
3034 /* is_void<_Ret> = */ true,
3035 __void_t<typename _Result::type>>
3038 using __nothrow_conv = true_type; // For is_nothrow_invocable_r
3041#pragma GCC diagnostic push
3042#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
3043 // Used for INVOKE<R> expressions to check the implicit conversion to R.
3044 template<typename _Result, typename _Ret>
3045 struct __is_invocable_impl<_Result, _Ret,
3046 /* is_void<_Ret> = */ false,
3047 __void_t<typename _Result::type>>
3050 // The type of the INVOKE expression.
3051 using _Res_t = typename _Result::type;
3053 // Unlike declval, this doesn't add_rvalue_reference, so it respects
3054 // guaranteed copy elision.
3055 static _Res_t _S_get() noexcept;
3057 // Used to check if _Res_t can implicitly convert to _Tp.
3058 template<typename _Tp>
3059 static void _S_conv(__type_identity_t<_Tp>) noexcept;
3061 // This overload is viable if INVOKE(f, args...) can convert to _Tp.
3062 template<typename _Tp,
3063 bool _Nothrow = noexcept(_S_conv<_Tp>(_S_get())),
3064 typename = decltype(_S_conv<_Tp>(_S_get())),
3065#if __has_builtin(__reference_converts_from_temporary)
3066 bool _Dangle = __reference_converts_from_temporary(_Tp, _Res_t)
3068 bool _Dangle = false
3071 static __bool_constant<_Nothrow && !_Dangle>
3074 template<typename _Tp, bool = false>
3079 // For is_invocable_r
3080 using type = decltype(_S_test<_Ret, /* Nothrow = */ true>(1));
3082 // For is_nothrow_invocable_r
3083 using __nothrow_conv = decltype(_S_test<_Ret>(1));
3085#pragma GCC diagnostic pop
3087 template<typename _Fn, typename... _ArgTypes>
3088 struct __is_invocable
3089 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
3092 template<typename _Fn, typename _Tp, typename... _Args>
3093 constexpr bool __call_is_nt(__invoke_memfun_ref)
3095 using _Up = typename __inv_unwrap<_Tp>::type;
3096 return noexcept((std::declval<_Up>().*std::declval<_Fn>())(
3097 std::declval<_Args>()...));
3100 template<typename _Fn, typename _Tp, typename... _Args>
3101 constexpr bool __call_is_nt(__invoke_memfun_deref)
3103 return noexcept(((*std::declval<_Tp>()).*std::declval<_Fn>())(
3104 std::declval<_Args>()...));
3107 template<typename _Fn, typename _Tp>
3108 constexpr bool __call_is_nt(__invoke_memobj_ref)
3110 using _Up = typename __inv_unwrap<_Tp>::type;
3111 return noexcept(std::declval<_Up>().*std::declval<_Fn>());
3114 template<typename _Fn, typename _Tp>
3115 constexpr bool __call_is_nt(__invoke_memobj_deref)
3117 return noexcept((*std::declval<_Tp>()).*std::declval<_Fn>());
3120 template<typename _Fn, typename... _Args>
3121 constexpr bool __call_is_nt(__invoke_other)
3123 return noexcept(std::declval<_Fn>()(std::declval<_Args>()...));
3126 template<typename _Result, typename _Fn, typename... _Args>
3127 struct __call_is_nothrow
3129 std::__call_is_nt<_Fn, _Args...>(typename _Result::__invoke_type{})
3133 template<typename _Fn, typename... _Args>
3134 using __call_is_nothrow_
3135 = __call_is_nothrow<__invoke_result<_Fn, _Args...>, _Fn, _Args...>;
3137 // __is_nothrow_invocable (std::is_nothrow_invocable for C++11)
3138 template<typename _Fn, typename... _Args>
3139 struct __is_nothrow_invocable
3140 : __and_<__is_invocable<_Fn, _Args...>,
3141 __call_is_nothrow_<_Fn, _Args...>>::type
3144#pragma GCC diagnostic push
3145#pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
3146 struct __nonesuchbase {};
3147 struct __nonesuch : private __nonesuchbase {
3148 ~__nonesuch() = delete;
3149 __nonesuch(__nonesuch const&) = delete;
3150 void operator=(__nonesuch const&) = delete;
3152#pragma GCC diagnostic pop
3155#ifdef __cpp_lib_is_invocable // C++ >= 17
3156 /// std::invoke_result
3157 template<typename _Functor, typename... _ArgTypes>
3158 struct invoke_result
3159 : public __invoke_result<_Functor, _ArgTypes...>
3161 static_assert(std::__is_complete_or_unbounded(__type_identity<_Functor>{}),
3162 "_Functor must be a complete class or an unbounded array");
3163 static_assert((std::__is_complete_or_unbounded(
3164 __type_identity<_ArgTypes>{}) && ...),
3165 "each argument type must be a complete class or an unbounded array");
3168 /// std::invoke_result_t
3169 template<typename _Fn, typename... _Args>
3170 using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
3172 /// std::is_invocable
3173 template<typename _Fn, typename... _ArgTypes>
3175 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
3177 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3178 "_Fn must be a complete class or an unbounded array");
3179 static_assert((std::__is_complete_or_unbounded(
3180 __type_identity<_ArgTypes>{}) && ...),
3181 "each argument type must be a complete class or an unbounded array");
3184 /// std::is_invocable_r
3185 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3186 struct is_invocable_r
3187 : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>::type
3189 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3190 "_Fn must be a complete class or an unbounded array");
3191 static_assert((std::__is_complete_or_unbounded(
3192 __type_identity<_ArgTypes>{}) && ...),
3193 "each argument type must be a complete class or an unbounded array");
3194 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3195 "_Ret must be a complete class or an unbounded array");
3198 /// std::is_nothrow_invocable
3199 template<typename _Fn, typename... _ArgTypes>
3200 struct is_nothrow_invocable
3201 : __and_<__is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>,
3202 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3204 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3205 "_Fn must be a complete class or an unbounded array");
3206 static_assert((std::__is_complete_or_unbounded(
3207 __type_identity<_ArgTypes>{}) && ...),
3208 "each argument type must be a complete class or an unbounded array");
3211 /// @cond undocumented
3212 // This checks that the INVOKE<R> expression is well-formed and that the
3213 // conversion to R does not throw. It does *not* check whether the INVOKE
3214 // expression itself can throw. That is done by __call_is_nothrow_ instead.
3215 template<typename _Result, typename _Ret>
3216 using __is_nt_invocable_impl
3217 = typename __is_invocable_impl<_Result, _Ret>::__nothrow_conv;
3220 /// std::is_nothrow_invocable_r
3221 template<typename _Ret, typename _Fn, typename... _ArgTypes>
3222 struct is_nothrow_invocable_r
3223 : __and_<__is_nt_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, _Ret>,
3224 __call_is_nothrow_<_Fn, _ArgTypes...>>::type
3226 static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
3227 "_Fn must be a complete class or an unbounded array");
3228 static_assert((std::__is_complete_or_unbounded(
3229 __type_identity<_ArgTypes>{}) && ...),
3230 "each argument type must be a complete class or an unbounded array");
3231 static_assert(std::__is_complete_or_unbounded(__type_identity<_Ret>{}),
3232 "_Ret must be a complete class or an unbounded array");
3234#endif // __cpp_lib_is_invocable
3236#if __cpp_lib_type_trait_variable_templates // C++ >= 17
3238 * @defgroup variable_templates Variable templates for type traits
3239 * @ingroup metaprogramming
3241 * Each variable `is_xxx_v<T>` is a boolean constant with the same value
3242 * as the `value` member of the corresponding type trait `is_xxx<T>`.
3244 * @since C++17 unless noted otherwise.
3249 * @ingroup variable_templates
3251template <typename _Tp>
3252 inline constexpr bool is_void_v = is_void<_Tp>::value;
3253template <typename _Tp>
3254 inline constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
3255template <typename _Tp>
3256 inline constexpr bool is_integral_v = is_integral<_Tp>::value;
3257template <typename _Tp>
3258 inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
3260#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_array)
3261template <typename _Tp>
3262 inline constexpr bool is_array_v = __is_array(_Tp);
3264template <typename _Tp>
3265 inline constexpr bool is_array_v = false;
3266template <typename _Tp>
3267 inline constexpr bool is_array_v<_Tp[]> = true;
3268template <typename _Tp, size_t _Num>
3269 inline constexpr bool is_array_v<_Tp[_Num]> = true;
3272template <typename _Tp>
3273 inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
3274template <typename _Tp>
3275 inline constexpr bool is_lvalue_reference_v = false;
3276template <typename _Tp>
3277 inline constexpr bool is_lvalue_reference_v<_Tp&> = true;
3278template <typename _Tp>
3279 inline constexpr bool is_rvalue_reference_v = false;
3280template <typename _Tp>
3281 inline constexpr bool is_rvalue_reference_v<_Tp&&> = true;
3283#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_object_pointer)
3284template <typename _Tp>
3285 inline constexpr bool is_member_object_pointer_v =
3286 __is_member_object_pointer(_Tp);
3288template <typename _Tp>
3289 inline constexpr bool is_member_object_pointer_v =
3290 is_member_object_pointer<_Tp>::value;
3293#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_function_pointer)
3294template <typename _Tp>
3295 inline constexpr bool is_member_function_pointer_v =
3296 __is_member_function_pointer(_Tp);
3298template <typename _Tp>
3299 inline constexpr bool is_member_function_pointer_v =
3300 is_member_function_pointer<_Tp>::value;
3303template <typename _Tp>
3304 inline constexpr bool is_enum_v = __is_enum(_Tp);
3305template <typename _Tp>
3306 inline constexpr bool is_union_v = __is_union(_Tp);
3307template <typename _Tp>
3308 inline constexpr bool is_class_v = __is_class(_Tp);
3309// is_function_v is defined below, after is_const_v.
3311#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_reference)
3312template <typename _Tp>
3313 inline constexpr bool is_reference_v = __is_reference(_Tp);
3315template <typename _Tp>
3316 inline constexpr bool is_reference_v = false;
3317template <typename _Tp>
3318 inline constexpr bool is_reference_v<_Tp&> = true;
3319template <typename _Tp>
3320 inline constexpr bool is_reference_v<_Tp&&> = true;
3323template <typename _Tp>
3324 inline constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
3325template <typename _Tp>
3326 inline constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
3328#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_object)
3329template <typename _Tp>
3330 inline constexpr bool is_object_v = __is_object(_Tp);
3332template <typename _Tp>
3333 inline constexpr bool is_object_v = is_object<_Tp>::value;
3336template <typename _Tp>
3337 inline constexpr bool is_scalar_v = is_scalar<_Tp>::value;
3338template <typename _Tp>
3339 inline constexpr bool is_compound_v = !is_fundamental_v<_Tp>;
3341#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_member_pointer)
3342template <typename _Tp>
3343 inline constexpr bool is_member_pointer_v = __is_member_pointer(_Tp);
3345template <typename _Tp>
3346 inline constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
3349template <typename _Tp>
3350 inline constexpr bool is_const_v = false;
3351template <typename _Tp>
3352 inline constexpr bool is_const_v<const _Tp> = true;
3354#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function)
3355template <typename _Tp>
3356 inline constexpr bool is_function_v = __is_function(_Tp);
3358template <typename _Tp>
3359 inline constexpr bool is_function_v = !is_const_v<const _Tp>;
3360template <typename _Tp>
3361 inline constexpr bool is_function_v<_Tp&> = false;
3362template <typename _Tp>
3363 inline constexpr bool is_function_v<_Tp&&> = false;
3366template <typename _Tp>
3367 inline constexpr bool is_volatile_v = false;
3368template <typename _Tp>
3369 inline constexpr bool is_volatile_v<volatile _Tp> = true;
3371template <typename _Tp>
3372 inline constexpr bool is_trivial_v = __is_trivial(_Tp);
3373template <typename _Tp>
3374 inline constexpr bool is_trivially_copyable_v = __is_trivially_copyable(_Tp);
3375template <typename _Tp>
3376 inline constexpr bool is_standard_layout_v = __is_standard_layout(_Tp);
3377template <typename _Tp>
3378 _GLIBCXX20_DEPRECATED_SUGGEST("is_standard_layout_v && is_trivial_v")
3379 inline constexpr bool is_pod_v = __is_pod(_Tp);
3380template <typename _Tp>
3381 _GLIBCXX17_DEPRECATED
3382 inline constexpr bool is_literal_type_v = __is_literal_type(_Tp);
3383template <typename _Tp>
3384 inline constexpr bool is_empty_v = __is_empty(_Tp);
3385template <typename _Tp>
3386 inline constexpr bool is_polymorphic_v = __is_polymorphic(_Tp);
3387template <typename _Tp>
3388 inline constexpr bool is_abstract_v = __is_abstract(_Tp);
3389template <typename _Tp>
3390 inline constexpr bool is_final_v = __is_final(_Tp);
3392template <typename _Tp>
3393 inline constexpr bool is_signed_v = is_signed<_Tp>::value;
3394template <typename _Tp>
3395 inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
3397template <typename _Tp, typename... _Args>
3398 inline constexpr bool is_constructible_v = __is_constructible(_Tp, _Args...);
3399template <typename _Tp>
3400 inline constexpr bool is_default_constructible_v = __is_constructible(_Tp);
3401template <typename _Tp>
3402 inline constexpr bool is_copy_constructible_v
3403 = __is_constructible(_Tp, __add_lval_ref_t<const _Tp>);
3404template <typename _Tp>
3405 inline constexpr bool is_move_constructible_v
3406 = __is_constructible(_Tp, __add_rval_ref_t<_Tp>);
3408template <typename _Tp, typename _Up>
3409 inline constexpr bool is_assignable_v = __is_assignable(_Tp, _Up);
3410template <typename _Tp>
3411 inline constexpr bool is_copy_assignable_v
3412 = __is_assignable(__add_lval_ref_t<_Tp>, __add_lval_ref_t<const _Tp>);
3413template <typename _Tp>
3414 inline constexpr bool is_move_assignable_v
3415 = __is_assignable(__add_lval_ref_t<_Tp>, __add_rval_ref_t<_Tp>);
3417template <typename _Tp>
3418 inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
3420template <typename _Tp, typename... _Args>
3421 inline constexpr bool is_trivially_constructible_v
3422 = __is_trivially_constructible(_Tp, _Args...);
3423template <typename _Tp>
3424 inline constexpr bool is_trivially_default_constructible_v
3425 = __is_trivially_constructible(_Tp);
3426template <typename _Tp>
3427 inline constexpr bool is_trivially_copy_constructible_v
3428 = __is_trivially_constructible(_Tp, __add_lval_ref_t<const _Tp>);
3429template <typename _Tp>
3430 inline constexpr bool is_trivially_move_constructible_v
3431 = __is_trivially_constructible(_Tp, __add_rval_ref_t<_Tp>);
3433template <typename _Tp, typename _Up>
3434 inline constexpr bool is_trivially_assignable_v
3435 = __is_trivially_assignable(_Tp, _Up);
3436template <typename _Tp>
3437 inline constexpr bool is_trivially_copy_assignable_v
3438 = __is_trivially_assignable(__add_lval_ref_t<_Tp>,
3439 __add_lval_ref_t<const _Tp>);
3440template <typename _Tp>
3441 inline constexpr bool is_trivially_move_assignable_v
3442 = __is_trivially_assignable(__add_lval_ref_t<_Tp>,
3443 __add_rval_ref_t<_Tp>);
3446template <typename _Tp>
3447 inline constexpr bool is_trivially_destructible_v = false;
3449template <typename _Tp>
3450 requires (!is_reference_v<_Tp>) && requires (_Tp& __t) { __t.~_Tp(); }
3451 inline constexpr bool is_trivially_destructible_v<_Tp>
3452 = __has_trivial_destructor(_Tp);
3453template <typename _Tp>
3454 inline constexpr bool is_trivially_destructible_v<_Tp&> = true;
3455template <typename _Tp>
3456 inline constexpr bool is_trivially_destructible_v<_Tp&&> = true;
3457template <typename _Tp, size_t _Nm>
3458 inline constexpr bool is_trivially_destructible_v<_Tp[_Nm]>
3459 = is_trivially_destructible_v<_Tp>;
3461template <typename _Tp>
3462 inline constexpr bool is_trivially_destructible_v =
3463 is_trivially_destructible<_Tp>::value;
3466template <typename _Tp, typename... _Args>
3467 inline constexpr bool is_nothrow_constructible_v
3468 = __is_nothrow_constructible(_Tp, _Args...);
3469template <typename _Tp>
3470 inline constexpr bool is_nothrow_default_constructible_v
3471 = __is_nothrow_constructible(_Tp);
3472template <typename _Tp>
3473 inline constexpr bool is_nothrow_copy_constructible_v
3474 = __is_nothrow_constructible(_Tp, __add_lval_ref_t<const _Tp>);
3475template <typename _Tp>
3476 inline constexpr bool is_nothrow_move_constructible_v
3477 = __is_nothrow_constructible(_Tp, __add_rval_ref_t<_Tp>);
3479template <typename _Tp, typename _Up>
3480 inline constexpr bool is_nothrow_assignable_v
3481 = __is_nothrow_assignable(_Tp, _Up);
3482template <typename _Tp>
3483 inline constexpr bool is_nothrow_copy_assignable_v
3484 = __is_nothrow_assignable(__add_lval_ref_t<_Tp>,
3485 __add_lval_ref_t<const _Tp>);
3486template <typename _Tp>
3487 inline constexpr bool is_nothrow_move_assignable_v
3488 = __is_nothrow_assignable(__add_lval_ref_t<_Tp>, __add_rval_ref_t<_Tp>);
3490template <typename _Tp>
3491 inline constexpr bool is_nothrow_destructible_v =
3492 is_nothrow_destructible<_Tp>::value;
3494template <typename _Tp>
3495 inline constexpr bool has_virtual_destructor_v
3496 = __has_virtual_destructor(_Tp);
3498template <typename _Tp>
3499 inline constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
3501template <typename _Tp>
3502 inline constexpr size_t rank_v = 0;
3503template <typename _Tp, size_t _Size>
3504 inline constexpr size_t rank_v<_Tp[_Size]> = 1 + rank_v<_Tp>;
3505template <typename _Tp>
3506 inline constexpr size_t rank_v<_Tp[]> = 1 + rank_v<_Tp>;
3508template <typename _Tp, unsigned _Idx = 0>
3509 inline constexpr size_t extent_v = 0;
3510template <typename _Tp, size_t _Size>
3511 inline constexpr size_t extent_v<_Tp[_Size], 0> = _Size;
3512template <typename _Tp, unsigned _Idx, size_t _Size>
3513 inline constexpr size_t extent_v<_Tp[_Size], _Idx> = extent_v<_Tp, _Idx - 1>;
3514template <typename _Tp>
3515 inline constexpr size_t extent_v<_Tp[], 0> = 0;
3516template <typename _Tp, unsigned _Idx>
3517 inline constexpr size_t extent_v<_Tp[], _Idx> = extent_v<_Tp, _Idx - 1>;
3519#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_same)
3520template <typename _Tp, typename _Up>
3521 inline constexpr bool is_same_v = __is_same(_Tp, _Up);
3523template <typename _Tp, typename _Up>
3524 inline constexpr bool is_same_v = false;
3525template <typename _Tp>
3526 inline constexpr bool is_same_v<_Tp, _Tp> = true;
3528template <typename _Base, typename _Derived>
3529 inline constexpr bool is_base_of_v = __is_base_of(_Base, _Derived);
3530#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_convertible)
3531template <typename _From, typename _To>
3532 inline constexpr bool is_convertible_v = __is_convertible(_From, _To);
3534template <typename _From, typename _To>
3535 inline constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
3537template<typename _Fn, typename... _Args>
3538 inline constexpr bool is_invocable_v = is_invocable<_Fn, _Args...>::value;
3539template<typename _Fn, typename... _Args>
3540 inline constexpr bool is_nothrow_invocable_v
3541 = is_nothrow_invocable<_Fn, _Args...>::value;
3542template<typename _Ret, typename _Fn, typename... _Args>
3543 inline constexpr bool is_invocable_r_v
3544 = is_invocable_r<_Ret, _Fn, _Args...>::value;
3545template<typename _Ret, typename _Fn, typename... _Args>
3546 inline constexpr bool is_nothrow_invocable_r_v
3547 = is_nothrow_invocable_r<_Ret, _Fn, _Args...>::value;
3549#endif // __cpp_lib_type_trait_variable_templates
3551#ifdef __cpp_lib_has_unique_object_representations // C++ >= 17 && HAS_UNIQ_OBJ_REP
3552 /// has_unique_object_representations
3554 template<typename _Tp>
3555 struct has_unique_object_representations
3556 : bool_constant<__has_unique_object_representations(
3557 remove_cv_t<remove_all_extents_t<_Tp>>
3560 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{}),
3561 "template argument must be a complete class or an unbounded array");
3564# if __cpp_lib_type_trait_variable_templates // C++ >= 17
3565 /// @ingroup variable_templates
3566 template<typename _Tp>
3567 inline constexpr bool has_unique_object_representations_v
3568 = has_unique_object_representations<_Tp>::value;
3572#ifdef __cpp_lib_is_aggregate // C++ >= 17 && builtin_is_aggregate
3573 /// is_aggregate - true if the type is an aggregate.
3575 template<typename _Tp>
3577 : bool_constant<__is_aggregate(remove_cv_t<_Tp>)>
3580# if __cpp_lib_type_trait_variable_templates // C++ >= 17
3581 /** is_aggregate_v - true if the type is an aggregate.
3582 * @ingroup variable_templates
3585 template<typename _Tp>
3586 inline constexpr bool is_aggregate_v = __is_aggregate(remove_cv_t<_Tp>);
3590 /** * Remove references and cv-qualifiers.
3594#ifdef __cpp_lib_remove_cvref // C++ >= 20
3595# if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_cvref)
3596 template<typename _Tp>
3598 { using type = __remove_cvref(_Tp); };
3600 template<typename _Tp>
3602 { using type = typename remove_cv<_Tp>::type; };
3604 template<typename _Tp>
3605 struct remove_cvref<_Tp&>
3606 { using type = typename remove_cv<_Tp>::type; };
3608 template<typename _Tp>
3609 struct remove_cvref<_Tp&&>
3610 { using type = typename remove_cv<_Tp>::type; };
3613 template<typename _Tp>
3614 using remove_cvref_t = typename remove_cvref<_Tp>::type;
3616#endif // __cpp_lib_remove_cvref
3618#ifdef __cpp_lib_type_identity // C++ >= 20
3619 /** * Identity metafunction.
3623 template<typename _Tp>
3624 struct type_identity { using type = _Tp; };
3626 template<typename _Tp>
3627 using type_identity_t = typename type_identity<_Tp>::type;
3631#ifdef __cpp_lib_unwrap_ref // C++ >= 20
3632 /** Unwrap a reference_wrapper
3636 template<typename _Tp>
3637 struct unwrap_reference { using type = _Tp; };
3639 template<typename _Tp>
3640 struct unwrap_reference<reference_wrapper<_Tp>> { using type = _Tp&; };
3642 template<typename _Tp>
3643 using unwrap_reference_t = typename unwrap_reference<_Tp>::type;
3646 /** Decay type and if it's a reference_wrapper, unwrap it
3650 template<typename _Tp>
3651 struct unwrap_ref_decay { using type = unwrap_reference_t<decay_t<_Tp>>; };
3653 template<typename _Tp>
3654 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
3656#endif // __cpp_lib_unwrap_ref
3658#ifdef __cpp_lib_bounded_array_traits // C++ >= 20
3659 /// True for a type that is an array of known bound.
3660 /// @ingroup variable_templates
3662# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_bounded_array)
3663 template<typename _Tp>
3664 inline constexpr bool is_bounded_array_v = __is_bounded_array(_Tp);
3666 template<typename _Tp>
3667 inline constexpr bool is_bounded_array_v = false;
3669 template<typename _Tp, size_t _Size>
3670 inline constexpr bool is_bounded_array_v<_Tp[_Size]> = true;
3673 /// True for a type that is an array of unknown bound.
3674 /// @ingroup variable_templates
3676 template<typename _Tp>
3677 inline constexpr bool is_unbounded_array_v = false;
3679 template<typename _Tp>
3680 inline constexpr bool is_unbounded_array_v<_Tp[]> = true;
3682 /// True for a type that is an array of known bound.
3684 template<typename _Tp>
3685 struct is_bounded_array
3686 : public bool_constant<is_bounded_array_v<_Tp>>
3689 /// True for a type that is an array of unknown bound.
3691 template<typename _Tp>
3692 struct is_unbounded_array
3693 : public bool_constant<is_unbounded_array_v<_Tp>>
3695#endif // __cpp_lib_bounded_array_traits
3697#if __has_builtin(__is_layout_compatible) && __cplusplus >= 202002L
3700 template<typename _Tp, typename _Up>
3701 struct is_layout_compatible
3702 : bool_constant<__is_layout_compatible(_Tp, _Up)>
3705 /// @ingroup variable_templates
3707 template<typename _Tp, typename _Up>
3708 constexpr bool is_layout_compatible_v
3709 = __is_layout_compatible(_Tp, _Up);
3711#if __has_builtin(__builtin_is_corresponding_member)
3712# ifndef __cpp_lib_is_layout_compatible
3713# error "libstdc++ bug: is_corresponding_member and is_layout_compatible are provided but their FTM is not set"
3717 template<typename _S1, typename _S2, typename _M1, typename _M2>
3719 is_corresponding_member(_M1 _S1::*__m1, _M2 _S2::*__m2) noexcept
3720 { return __builtin_is_corresponding_member(__m1, __m2); }
3724#if __has_builtin(__is_pointer_interconvertible_base_of) \
3725 && __cplusplus >= 202002L
3726 /// True if `_Derived` is standard-layout and has a base class of type `_Base`
3728 template<typename _Base, typename _Derived>
3729 struct is_pointer_interconvertible_base_of
3730 : bool_constant<__is_pointer_interconvertible_base_of(_Base, _Derived)>
3733 /// @ingroup variable_templates
3735 template<typename _Base, typename _Derived>
3736 constexpr bool is_pointer_interconvertible_base_of_v
3737 = __is_pointer_interconvertible_base_of(_Base, _Derived);
3739#if __has_builtin(__builtin_is_pointer_interconvertible_with_class)
3740# ifndef __cpp_lib_is_pointer_interconvertible
3741# error "libstdc++ bug: is_pointer_interconvertible available but FTM is not set"
3744 /// True if `__mp` points to the first member of a standard-layout type
3745 /// @returns true if `s.*__mp` is pointer-interconvertible with `s`
3747 template<typename _Tp, typename _Mem>
3749 is_pointer_interconvertible_with_class(_Mem _Tp::*__mp) noexcept
3750 { return __builtin_is_pointer_interconvertible_with_class(__mp); }
3754#ifdef __cpp_lib_is_scoped_enum // C++ >= 23
3755 /// True if the type is a scoped enumeration type.
3758# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
3759 template<typename _Tp>
3760 struct is_scoped_enum
3761 : bool_constant<__is_scoped_enum(_Tp)>
3764 template<typename _Tp>
3765 struct is_scoped_enum
3769 template<typename _Tp>
3770 requires __is_enum(_Tp)
3771 && requires(remove_cv_t<_Tp> __t) { __t = __t; } // fails if incomplete
3772 struct is_scoped_enum<_Tp>
3773 : bool_constant<!requires(_Tp __t, void(*__f)(int)) { __f(__t); }>
3777 /// @ingroup variable_templates
3779# if _GLIBCXX_USE_BUILTIN_TRAIT(__is_scoped_enum)
3780 template<typename _Tp>
3781 inline constexpr bool is_scoped_enum_v = __is_scoped_enum(_Tp);
3783 template<typename _Tp>
3784 inline constexpr bool is_scoped_enum_v = is_scoped_enum<_Tp>::value;
3788#ifdef __cpp_lib_reference_from_temporary // C++ >= 23 && ref_{converts,constructs}_from_temp
3789 /// True if _Tp is a reference type, a _Up value can be bound to _Tp in
3790 /// direct-initialization, and a temporary object would be bound to
3791 /// the reference, false otherwise.
3793 template<typename _Tp, typename _Up>
3794 struct reference_constructs_from_temporary
3795 : public bool_constant<__reference_constructs_from_temporary(_Tp, _Up)>
3797 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{})
3798 && std::__is_complete_or_unbounded(__type_identity<_Up>{}),
3799 "template argument must be a complete class or an unbounded array");
3802 /// True if _Tp is a reference type, a _Up value can be bound to _Tp in
3803 /// copy-initialization, and a temporary object would be bound to
3804 /// the reference, false otherwise.
3806 template<typename _Tp, typename _Up>
3807 struct reference_converts_from_temporary
3808 : public bool_constant<__reference_converts_from_temporary(_Tp, _Up)>
3810 static_assert(std::__is_complete_or_unbounded(__type_identity<_Tp>{})
3811 && std::__is_complete_or_unbounded(__type_identity<_Up>{}),
3812 "template argument must be a complete class or an unbounded array");
3815 /// @ingroup variable_templates
3817 template<typename _Tp, typename _Up>
3818 inline constexpr bool reference_constructs_from_temporary_v
3819 = reference_constructs_from_temporary<_Tp, _Up>::value;
3821 /// @ingroup variable_templates
3823 template<typename _Tp, typename _Up>
3824 inline constexpr bool reference_converts_from_temporary_v
3825 = reference_converts_from_temporary<_Tp, _Up>::value;
3826#endif // __cpp_lib_reference_from_temporary
3828#ifdef __cpp_lib_is_constant_evaluated // C++ >= 20 && HAVE_IS_CONST_EVAL
3829 /// Returns true only when called during constant evaluation.
3831 constexpr inline bool
3832 is_constant_evaluated() noexcept
3834#if __cpp_if_consteval >= 202106L
3835 if consteval { return true; } else { return false; }
3837 return __builtin_is_constant_evaluated();
3842#if __cplusplus >= 202002L
3843 /// @cond undocumented
3844 template<typename _From, typename _To>
3845 using __copy_cv = typename __match_cv_qualifiers<_From, _To>::__type;
3847 template<typename _Xp, typename _Yp>
3849 = decltype(false ? declval<_Xp(&)()>()() : declval<_Yp(&)()>()());
3851 template<typename _Ap, typename _Bp, typename = void>
3852 struct __common_ref_impl
3855 // [meta.trans.other], COMMON-REF(A, B)
3856 template<typename _Ap, typename _Bp>
3857 using __common_ref = typename __common_ref_impl<_Ap, _Bp>::type;
3859 // COND-RES(COPYCV(X, Y) &, COPYCV(Y, X) &)
3860 template<typename _Xp, typename _Yp>
3861 using __condres_cvref
3862 = __cond_res<__copy_cv<_Xp, _Yp>&, __copy_cv<_Yp, _Xp>&>;
3864 // If A and B are both lvalue reference types, ...
3865 template<typename _Xp, typename _Yp>
3866 struct __common_ref_impl<_Xp&, _Yp&, __void_t<__condres_cvref<_Xp, _Yp>>>
3867 : enable_if<is_reference_v<__condres_cvref<_Xp, _Yp>>,
3868 __condres_cvref<_Xp, _Yp>>
3871 // let C be remove_reference_t<COMMON-REF(X&, Y&)>&&
3872 template<typename _Xp, typename _Yp>
3873 using __common_ref_C = remove_reference_t<__common_ref<_Xp&, _Yp&>>&&;
3875 // If A and B are both rvalue reference types, ...
3876 template<typename _Xp, typename _Yp>
3877 struct __common_ref_impl<_Xp&&, _Yp&&,
3878 _Require<is_convertible<_Xp&&, __common_ref_C<_Xp, _Yp>>,
3879 is_convertible<_Yp&&, __common_ref_C<_Xp, _Yp>>>>
3880 { using type = __common_ref_C<_Xp, _Yp>; };
3882 // let D be COMMON-REF(const X&, Y&)
3883 template<typename _Xp, typename _Yp>
3884 using __common_ref_D = __common_ref<const _Xp&, _Yp&>;
3886 // If A is an rvalue reference and B is an lvalue reference, ...
3887 template<typename _Xp, typename _Yp>
3888 struct __common_ref_impl<_Xp&&, _Yp&,
3889 _Require<is_convertible<_Xp&&, __common_ref_D<_Xp, _Yp>>>>
3890 { using type = __common_ref_D<_Xp, _Yp>; };
3892 // If A is an lvalue reference and B is an rvalue reference, ...
3893 template<typename _Xp, typename _Yp>
3894 struct __common_ref_impl<_Xp&, _Yp&&>
3895 : __common_ref_impl<_Yp&&, _Xp&>
3899 template<typename _Tp, typename _Up,
3900 template<typename> class _TQual, template<typename> class _UQual>
3901 struct basic_common_reference
3904 /// @cond undocumented
3905 template<typename _Tp>
3907 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>; };
3909 template<typename _Tp>
3911 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&; };
3913 template<typename _Tp>
3914 struct __xref<_Tp&&>
3915 { template<typename _Up> using __type = __copy_cv<_Tp, _Up>&&; };
3917 template<typename _Tp1, typename _Tp2>
3918 using __basic_common_ref
3919 = typename basic_common_reference<remove_cvref_t<_Tp1>,
3920 remove_cvref_t<_Tp2>,
3921 __xref<_Tp1>::template __type,
3922 __xref<_Tp2>::template __type>::type;
3925 template<typename... _Tp>
3926 struct common_reference;
3928 template<typename... _Tp>
3929 using common_reference_t = typename common_reference<_Tp...>::type;
3931 // If sizeof...(T) is zero, there shall be no member type.
3933 struct common_reference<>
3936 // If sizeof...(T) is one ...
3937 template<typename _Tp0>
3938 struct common_reference<_Tp0>
3939 { using type = _Tp0; };
3941 /// @cond undocumented
3942 template<typename _Tp1, typename _Tp2, int _Bullet = 1, typename = void>
3943 struct __common_reference_impl
3944 : __common_reference_impl<_Tp1, _Tp2, _Bullet + 1>
3947 // If sizeof...(T) is two ...
3948 template<typename _Tp1, typename _Tp2>
3949 struct common_reference<_Tp1, _Tp2>
3950 : __common_reference_impl<_Tp1, _Tp2>
3953 // If T1 and T2 are reference types and COMMON-REF(T1, T2) is well-formed, ...
3954 template<typename _Tp1, typename _Tp2>
3955 struct __common_reference_impl<_Tp1&, _Tp2&, 1,
3956 void_t<__common_ref<_Tp1&, _Tp2&>>>
3957 { using type = __common_ref<_Tp1&, _Tp2&>; };
3959 template<typename _Tp1, typename _Tp2>
3960 struct __common_reference_impl<_Tp1&&, _Tp2&&, 1,
3961 void_t<__common_ref<_Tp1&&, _Tp2&&>>>
3962 { using type = __common_ref<_Tp1&&, _Tp2&&>; };
3964 template<typename _Tp1, typename _Tp2>
3965 struct __common_reference_impl<_Tp1&, _Tp2&&, 1,
3966 void_t<__common_ref<_Tp1&, _Tp2&&>>>
3967 { using type = __common_ref<_Tp1&, _Tp2&&>; };
3969 template<typename _Tp1, typename _Tp2>
3970 struct __common_reference_impl<_Tp1&&, _Tp2&, 1,
3971 void_t<__common_ref<_Tp1&&, _Tp2&>>>
3972 { using type = __common_ref<_Tp1&&, _Tp2&>; };
3974 // Otherwise, if basic_common_reference<...>::type is well-formed, ...
3975 template<typename _Tp1, typename _Tp2>
3976 struct __common_reference_impl<_Tp1, _Tp2, 2,
3977 void_t<__basic_common_ref<_Tp1, _Tp2>>>
3978 { using type = __basic_common_ref<_Tp1, _Tp2>; };
3980 // Otherwise, if COND-RES(T1, T2) is well-formed, ...
3981 template<typename _Tp1, typename _Tp2>
3982 struct __common_reference_impl<_Tp1, _Tp2, 3,
3983 void_t<__cond_res<_Tp1, _Tp2>>>
3984 { using type = __cond_res<_Tp1, _Tp2>; };
3986 // Otherwise, if common_type_t<T1, T2> is well-formed, ...
3987 template<typename _Tp1, typename _Tp2>
3988 struct __common_reference_impl<_Tp1, _Tp2, 4,
3989 void_t<common_type_t<_Tp1, _Tp2>>>
3990 { using type = common_type_t<_Tp1, _Tp2>; };
3992 // Otherwise, there shall be no member type.
3993 template<typename _Tp1, typename _Tp2>
3994 struct __common_reference_impl<_Tp1, _Tp2, 5, void>
3997 // Otherwise, if sizeof...(T) is greater than two, ...
3998 template<typename _Tp1, typename _Tp2, typename... _Rest>
3999 struct common_reference<_Tp1, _Tp2, _Rest...>
4000 : __common_type_fold<common_reference<_Tp1, _Tp2>,
4001 __common_type_pack<_Rest...>>
4004 // Reuse __common_type_fold for common_reference<T1, T2, Rest...>
4005 template<typename _Tp1, typename _Tp2, typename... _Rest>
4006 struct __common_type_fold<common_reference<_Tp1, _Tp2>,
4007 __common_type_pack<_Rest...>,
4008 void_t<common_reference_t<_Tp1, _Tp2>>>
4009 : public common_reference<common_reference_t<_Tp1, _Tp2>, _Rest...>
4015 /// @} group metaprogramming
4017_GLIBCXX_END_NAMESPACE_VERSION
4022#endif // _GLIBCXX_TYPE_TRAITS