[2/2] libstdc++: Implement C++23 std::bind_pack from P2387R3 [PR108827]

Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

	PR libstdc++/108827
	PR libstdc++/111327

libstdc++-v3/ChangeLog:

	* include/bits/version.def (bind_back): Define.
	* include/bits/version.h: Regenerate.
	* include/std/functional (_Bind_back): Define for C++23.
	(bind_back): Likewise.
	* testsuite/20_util/function_objects/bind_back/1.cc: New test
	(adapted from corresponding bind_front test).
	* testsuite/20_util/function_objects/bind_back/111327.cc: Likewise.
---
 libstdc++-v3/include/bits/version.def         |   9 +
 libstdc++-v3/include/bits/version.h           | 221 +++++++++---------
 libstdc++-v3/include/std/functional           |  71 ++++++
 .../20_util/function_objects/bind_back/1.cc   | 178 ++++++++++++++
 .../function_objects/bind_back/111327.cc      |  42 ++++
 5 files changed, 416 insertions(+), 105 deletions(-)
 create mode 100644 libstdc++-v3/testsuite/20_util/function_objects/bind_back/1.cc
 create mode 100644 libstdc++-v3/testsuite/20_util/function_objects/bind_back/111327.cc

On Fri, 12 Jan 2024 at 20:10, Patrick Palka <ppalka@redhat.com> wrote:
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

OK


>
>         PR libstdc++/108827
>         PR libstdc++/111327
>
> libstdc++-v3/ChangeLog:
>
>         * include/bits/version.def (bind_back): Define.
>         * include/bits/version.h: Regenerate.
>         * include/std/functional (_Bind_back): Define for C++23.
>         (bind_back): Likewise.
>         * testsuite/20_util/function_objects/bind_back/1.cc: New test
>         (adapted from corresponding bind_front test).
>         * testsuite/20_util/function_objects/bind_back/111327.cc: Likewise.
> ---
>  libstdc++-v3/include/bits/version.def         |   9 +
>  libstdc++-v3/include/bits/version.h           | 221 +++++++++---------
>  libstdc++-v3/include/std/functional           |  71 ++++++
>  .../20_util/function_objects/bind_back/1.cc   | 178 ++++++++++++++
>  .../function_objects/bind_back/111327.cc      |  42 ++++
>  5 files changed, 416 insertions(+), 105 deletions(-)
>  create mode 100644 libstdc++-v3/testsuite/20_util/function_objects/bind_back/1.cc
>  create mode 100644 libstdc++-v3/testsuite/20_util/function_objects/bind_back/111327.cc
>
> diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
> index 7c7ba066161..21cdc65121b 100644
> --- a/libstdc++-v3/include/bits/version.def
> +++ b/libstdc++-v3/include/bits/version.def
> @@ -766,6 +766,15 @@ ftms = {
>    };
>  };
>
> +ftms = {
> +  name = bind_back;
> +  values = {
> +    v = 202202;
> +    cxxmin = 23;
> +    extra_cond = "__cpp_explicit_this_parameter";
> +  };
> +};
> +
>  ftms = {
>    name = starts_ends_with;
>    values = {
> diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
> index 65d5164347e..f8dd16416a4 100644
> --- a/libstdc++-v3/include/bits/version.h
> +++ b/libstdc++-v3/include/bits/version.h
> @@ -937,6 +937,17 @@
>  #undef __glibcxx_want_bind_front
>
>  // from version.def line 770
> +#if !defined(__cpp_lib_bind_back)
> +# if (__cplusplus >= 202100L) && (__cpp_explicit_this_parameter)
> +#  define __glibcxx_bind_back 202202L
> +#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_bind_back)
> +#   define __cpp_lib_bind_back 202202L
> +#  endif
> +# endif
> +#endif /* !defined(__cpp_lib_bind_back) && defined(__glibcxx_want_bind_back) */
> +#undef __glibcxx_want_bind_back
> +
> +// from version.def line 779
>  #if !defined(__cpp_lib_starts_ends_with)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_starts_ends_with 201711L
> @@ -947,7 +958,7 @@
>  #endif /* !defined(__cpp_lib_starts_ends_with) && defined(__glibcxx_want_starts_ends_with) */
>  #undef __glibcxx_want_starts_ends_with
>
> -// from version.def line 778
> +// from version.def line 787
>  #if !defined(__cpp_lib_bit_cast)
>  # if (__cplusplus >= 202002L) && (__has_builtin(__builtin_bit_cast))
>  #  define __glibcxx_bit_cast 201806L
> @@ -958,7 +969,7 @@
>  #endif /* !defined(__cpp_lib_bit_cast) && defined(__glibcxx_want_bit_cast) */
>  #undef __glibcxx_want_bit_cast
>
> -// from version.def line 787
> +// from version.def line 796
>  #if !defined(__cpp_lib_bitops)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_bitops 201907L
> @@ -969,7 +980,7 @@
>  #endif /* !defined(__cpp_lib_bitops) && defined(__glibcxx_want_bitops) */
>  #undef __glibcxx_want_bitops
>
> -// from version.def line 795
> +// from version.def line 804
>  #if !defined(__cpp_lib_bounded_array_traits)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_bounded_array_traits 201902L
> @@ -980,7 +991,7 @@
>  #endif /* !defined(__cpp_lib_bounded_array_traits) && defined(__glibcxx_want_bounded_array_traits) */
>  #undef __glibcxx_want_bounded_array_traits
>
> -// from version.def line 803
> +// from version.def line 812
>  #if !defined(__cpp_lib_concepts)
>  # if (__cplusplus >= 202002L) && (__cpp_concepts >= 201907L)
>  #  define __glibcxx_concepts 202002L
> @@ -991,7 +1002,7 @@
>  #endif /* !defined(__cpp_lib_concepts) && defined(__glibcxx_want_concepts) */
>  #undef __glibcxx_want_concepts
>
> -// from version.def line 813
> +// from version.def line 822
>  #if !defined(__cpp_lib_optional)
>  # if (__cplusplus >= 202100L) && (__glibcxx_concepts)
>  #  define __glibcxx_optional 202110L
> @@ -1012,7 +1023,7 @@
>  #endif /* !defined(__cpp_lib_optional) && defined(__glibcxx_want_optional) */
>  #undef __glibcxx_want_optional
>
> -// from version.def line 830
> +// from version.def line 839
>  #if !defined(__cpp_lib_destroying_delete)
>  # if (__cplusplus >= 202002L) && (__cpp_impl_destroying_delete)
>  #  define __glibcxx_destroying_delete 201806L
> @@ -1023,7 +1034,7 @@
>  #endif /* !defined(__cpp_lib_destroying_delete) && defined(__glibcxx_want_destroying_delete) */
>  #undef __glibcxx_want_destroying_delete
>
> -// from version.def line 839
> +// from version.def line 848
>  #if !defined(__cpp_lib_constexpr_string_view)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_string_view 201811L
> @@ -1034,7 +1045,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_string_view) && defined(__glibcxx_want_constexpr_string_view) */
>  #undef __glibcxx_want_constexpr_string_view
>
> -// from version.def line 847
> +// from version.def line 856
>  #if !defined(__cpp_lib_endian)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_endian 201907L
> @@ -1045,7 +1056,7 @@
>  #endif /* !defined(__cpp_lib_endian) && defined(__glibcxx_want_endian) */
>  #undef __glibcxx_want_endian
>
> -// from version.def line 855
> +// from version.def line 864
>  #if !defined(__cpp_lib_int_pow2)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_int_pow2 202002L
> @@ -1056,7 +1067,7 @@
>  #endif /* !defined(__cpp_lib_int_pow2) && defined(__glibcxx_want_int_pow2) */
>  #undef __glibcxx_want_int_pow2
>
> -// from version.def line 863
> +// from version.def line 872
>  #if !defined(__cpp_lib_integer_comparison_functions)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_integer_comparison_functions 202002L
> @@ -1067,7 +1078,7 @@
>  #endif /* !defined(__cpp_lib_integer_comparison_functions) && defined(__glibcxx_want_integer_comparison_functions) */
>  #undef __glibcxx_want_integer_comparison_functions
>
> -// from version.def line 871
> +// from version.def line 880
>  #if !defined(__cpp_lib_is_constant_evaluated)
>  # if (__cplusplus >= 202002L) && (defined(_GLIBCXX_HAVE_IS_CONSTANT_EVALUATED))
>  #  define __glibcxx_is_constant_evaluated 201811L
> @@ -1078,7 +1089,7 @@
>  #endif /* !defined(__cpp_lib_is_constant_evaluated) && defined(__glibcxx_want_is_constant_evaluated) */
>  #undef __glibcxx_want_is_constant_evaluated
>
> -// from version.def line 881
> +// from version.def line 890
>  #if !defined(__cpp_lib_constexpr_char_traits)
>  # if (__cplusplus >= 202002L) && (defined(__glibcxx_is_constant_evaluated))
>  #  define __glibcxx_constexpr_char_traits 201811L
> @@ -1094,7 +1105,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_char_traits) && defined(__glibcxx_want_constexpr_char_traits) */
>  #undef __glibcxx_want_constexpr_char_traits
>
> -// from version.def line 897
> +// from version.def line 906
>  #if !defined(__cpp_lib_is_layout_compatible)
>  # if (__cplusplus >= 202002L) && (__has_builtin(__is_layout_compatible) && __has_builtin(__builtin_is_corresponding_member))
>  #  define __glibcxx_is_layout_compatible 201907L
> @@ -1105,7 +1116,7 @@
>  #endif /* !defined(__cpp_lib_is_layout_compatible) && defined(__glibcxx_want_is_layout_compatible) */
>  #undef __glibcxx_want_is_layout_compatible
>
> -// from version.def line 907
> +// from version.def line 916
>  #if !defined(__cpp_lib_is_nothrow_convertible)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_is_nothrow_convertible 201806L
> @@ -1116,7 +1127,7 @@
>  #endif /* !defined(__cpp_lib_is_nothrow_convertible) && defined(__glibcxx_want_is_nothrow_convertible) */
>  #undef __glibcxx_want_is_nothrow_convertible
>
> -// from version.def line 915
> +// from version.def line 924
>  #if !defined(__cpp_lib_is_pointer_interconvertible)
>  # if (__cplusplus >= 202002L) && (__has_builtin(__is_pointer_interconvertible_base_of) && __has_builtin(__builtin_is_pointer_interconvertible_with_class))
>  #  define __glibcxx_is_pointer_interconvertible 201907L
> @@ -1127,7 +1138,7 @@
>  #endif /* !defined(__cpp_lib_is_pointer_interconvertible) && defined(__glibcxx_want_is_pointer_interconvertible) */
>  #undef __glibcxx_want_is_pointer_interconvertible
>
> -// from version.def line 926
> +// from version.def line 935
>  #if !defined(__cpp_lib_math_constants)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_math_constants 201907L
> @@ -1138,7 +1149,7 @@
>  #endif /* !defined(__cpp_lib_math_constants) && defined(__glibcxx_want_math_constants) */
>  #undef __glibcxx_want_math_constants
>
> -// from version.def line 934
> +// from version.def line 943
>  #if !defined(__cpp_lib_make_obj_using_allocator)
>  # if (__cplusplus >= 202002L) && (__cpp_concepts)
>  #  define __glibcxx_make_obj_using_allocator 201811L
> @@ -1149,7 +1160,7 @@
>  #endif /* !defined(__cpp_lib_make_obj_using_allocator) && defined(__glibcxx_want_make_obj_using_allocator) */
>  #undef __glibcxx_want_make_obj_using_allocator
>
> -// from version.def line 944
> +// from version.def line 953
>  #if !defined(__cpp_lib_remove_cvref)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_remove_cvref 201711L
> @@ -1160,7 +1171,7 @@
>  #endif /* !defined(__cpp_lib_remove_cvref) && defined(__glibcxx_want_remove_cvref) */
>  #undef __glibcxx_want_remove_cvref
>
> -// from version.def line 952
> +// from version.def line 961
>  #if !defined(__cpp_lib_source_location)
>  # if (__cplusplus >= 202002L) && (__has_builtin(__builtin_source_location))
>  #  define __glibcxx_source_location 201907L
> @@ -1171,7 +1182,7 @@
>  #endif /* !defined(__cpp_lib_source_location) && defined(__glibcxx_want_source_location) */
>  #undef __glibcxx_want_source_location
>
> -// from version.def line 961
> +// from version.def line 970
>  #if !defined(__cpp_lib_span)
>  # if (__cplusplus >  202302L) && (__glibcxx_concepts)
>  #  define __glibcxx_span 202311L
> @@ -1187,7 +1198,7 @@
>  #endif /* !defined(__cpp_lib_span) && defined(__glibcxx_want_span) */
>  #undef __glibcxx_want_span
>
> -// from version.def line 975
> +// from version.def line 984
>  #if !defined(__cpp_lib_ssize)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_ssize 201902L
> @@ -1198,7 +1209,7 @@
>  #endif /* !defined(__cpp_lib_ssize) && defined(__glibcxx_want_ssize) */
>  #undef __glibcxx_want_ssize
>
> -// from version.def line 983
> +// from version.def line 992
>  #if !defined(__cpp_lib_three_way_comparison)
>  # if (__cplusplus >= 202002L) && (__cpp_impl_three_way_comparison >= 201907L && __glibcxx_concepts)
>  #  define __glibcxx_three_way_comparison 201907L
> @@ -1209,7 +1220,7 @@
>  #endif /* !defined(__cpp_lib_three_way_comparison) && defined(__glibcxx_want_three_way_comparison) */
>  #undef __glibcxx_want_three_way_comparison
>
> -// from version.def line 993
> +// from version.def line 1002
>  #if !defined(__cpp_lib_to_address)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_to_address 201711L
> @@ -1220,7 +1231,7 @@
>  #endif /* !defined(__cpp_lib_to_address) && defined(__glibcxx_want_to_address) */
>  #undef __glibcxx_want_to_address
>
> -// from version.def line 1001
> +// from version.def line 1010
>  #if !defined(__cpp_lib_to_array)
>  # if (__cplusplus >= 202002L) && (__cpp_generic_lambdas >= 201707L)
>  #  define __glibcxx_to_array 201907L
> @@ -1231,7 +1242,7 @@
>  #endif /* !defined(__cpp_lib_to_array) && defined(__glibcxx_want_to_array) */
>  #undef __glibcxx_want_to_array
>
> -// from version.def line 1010
> +// from version.def line 1019
>  #if !defined(__cpp_lib_type_identity)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_type_identity 201806L
> @@ -1242,7 +1253,7 @@
>  #endif /* !defined(__cpp_lib_type_identity) && defined(__glibcxx_want_type_identity) */
>  #undef __glibcxx_want_type_identity
>
> -// from version.def line 1018
> +// from version.def line 1027
>  #if !defined(__cpp_lib_unwrap_ref)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_unwrap_ref 201811L
> @@ -1253,7 +1264,7 @@
>  #endif /* !defined(__cpp_lib_unwrap_ref) && defined(__glibcxx_want_unwrap_ref) */
>  #undef __glibcxx_want_unwrap_ref
>
> -// from version.def line 1026
> +// from version.def line 1035
>  #if !defined(__cpp_lib_constexpr_iterator)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_iterator 201811L
> @@ -1264,7 +1275,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_iterator) && defined(__glibcxx_want_constexpr_iterator) */
>  #undef __glibcxx_want_constexpr_iterator
>
> -// from version.def line 1034
> +// from version.def line 1043
>  #if !defined(__cpp_lib_interpolate)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_interpolate 201902L
> @@ -1275,7 +1286,7 @@
>  #endif /* !defined(__cpp_lib_interpolate) && defined(__glibcxx_want_interpolate) */
>  #undef __glibcxx_want_interpolate
>
> -// from version.def line 1042
> +// from version.def line 1051
>  #if !defined(__cpp_lib_constexpr_utility)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_utility 201811L
> @@ -1286,7 +1297,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_utility) && defined(__glibcxx_want_constexpr_utility) */
>  #undef __glibcxx_want_constexpr_utility
>
> -// from version.def line 1050
> +// from version.def line 1059
>  #if !defined(__cpp_lib_shift)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_shift 201806L
> @@ -1297,7 +1308,7 @@
>  #endif /* !defined(__cpp_lib_shift) && defined(__glibcxx_want_shift) */
>  #undef __glibcxx_want_shift
>
> -// from version.def line 1058
> +// from version.def line 1067
>  #if !defined(__cpp_lib_ranges)
>  # if (__cplusplus >= 202100L) && (__glibcxx_concepts)
>  #  define __glibcxx_ranges 202211L
> @@ -1313,7 +1324,7 @@
>  #endif /* !defined(__cpp_lib_ranges) && defined(__glibcxx_want_ranges) */
>  #undef __glibcxx_want_ranges
>
> -// from version.def line 1072
> +// from version.def line 1081
>  #if !defined(__cpp_lib_constexpr_numeric)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_numeric 201911L
> @@ -1324,7 +1335,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_numeric) && defined(__glibcxx_want_constexpr_numeric) */
>  #undef __glibcxx_want_constexpr_numeric
>
> -// from version.def line 1080
> +// from version.def line 1089
>  #if !defined(__cpp_lib_constexpr_functional)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_functional 201907L
> @@ -1335,7 +1346,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_functional) && defined(__glibcxx_want_constexpr_functional) */
>  #undef __glibcxx_want_constexpr_functional
>
> -// from version.def line 1088
> +// from version.def line 1097
>  #if !defined(__cpp_lib_constexpr_algorithms)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_algorithms 201806L
> @@ -1346,7 +1357,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_algorithms) && defined(__glibcxx_want_constexpr_algorithms) */
>  #undef __glibcxx_want_constexpr_algorithms
>
> -// from version.def line 1096
> +// from version.def line 1105
>  #if !defined(__cpp_lib_constexpr_tuple)
>  # if (__cplusplus >= 202002L)
>  #  define __glibcxx_constexpr_tuple 201811L
> @@ -1357,7 +1368,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_tuple) && defined(__glibcxx_want_constexpr_tuple) */
>  #undef __glibcxx_want_constexpr_tuple
>
> -// from version.def line 1104
> +// from version.def line 1113
>  #if !defined(__cpp_lib_constexpr_memory)
>  # if (__cplusplus >= 202100L) && (__cpp_constexpr_dynamic_alloc)
>  #  define __glibcxx_constexpr_memory 202202L
> @@ -1373,7 +1384,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_memory) && defined(__glibcxx_want_constexpr_memory) */
>  #undef __glibcxx_want_constexpr_memory
>
> -// from version.def line 1117
> +// from version.def line 1126
>  #if !defined(__cpp_lib_atomic_shared_ptr)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_atomic_shared_ptr 201711L
> @@ -1384,7 +1395,7 @@
>  #endif /* !defined(__cpp_lib_atomic_shared_ptr) && defined(__glibcxx_want_atomic_shared_ptr) */
>  #undef __glibcxx_want_atomic_shared_ptr
>
> -// from version.def line 1126
> +// from version.def line 1135
>  #if !defined(__cpp_lib_atomic_wait)
>  # if (__cplusplus >= 202002L) && defined(_GLIBCXX_HAS_GTHREADS) && _GLIBCXX_HOSTED
>  #  define __glibcxx_atomic_wait 201907L
> @@ -1400,7 +1411,7 @@
>  #endif /* !defined(__cpp_lib_atomic_wait) && defined(__glibcxx_want_atomic_wait) */
>  #undef __glibcxx_want_atomic_wait
>
> -// from version.def line 1144
> +// from version.def line 1153
>  #if !defined(__cpp_lib_barrier)
>  # if (__cplusplus >= 202002L) && (__cpp_aligned_new && __glibcxx_atomic_wait)
>  #  define __glibcxx_barrier 201907L
> @@ -1411,7 +1422,7 @@
>  #endif /* !defined(__cpp_lib_barrier) && defined(__glibcxx_want_barrier) */
>  #undef __glibcxx_want_barrier
>
> -// from version.def line 1161
> +// from version.def line 1170
>  #if !defined(__cpp_lib_format)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_format 202110L
> @@ -1422,7 +1433,7 @@
>  #endif /* !defined(__cpp_lib_format) && defined(__glibcxx_want_format) */
>  #undef __glibcxx_want_format
>
> -// from version.def line 1170
> +// from version.def line 1179
>  #if !defined(__cpp_lib_format_uchar)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_format_uchar 202311L
> @@ -1433,7 +1444,7 @@
>  #endif /* !defined(__cpp_lib_format_uchar) && defined(__glibcxx_want_format_uchar) */
>  #undef __glibcxx_want_format_uchar
>
> -// from version.def line 1181
> +// from version.def line 1190
>  #if !defined(__cpp_lib_constexpr_complex)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_constexpr_complex 201711L
> @@ -1444,7 +1455,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_complex) && defined(__glibcxx_want_constexpr_complex) */
>  #undef __glibcxx_want_constexpr_complex
>
> -// from version.def line 1190
> +// from version.def line 1199
>  #if !defined(__cpp_lib_constexpr_dynamic_alloc)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_constexpr_dynamic_alloc 201907L
> @@ -1455,7 +1466,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_dynamic_alloc) && defined(__glibcxx_want_constexpr_dynamic_alloc) */
>  #undef __glibcxx_want_constexpr_dynamic_alloc
>
> -// from version.def line 1199
> +// from version.def line 1208
>  #if !defined(__cpp_lib_constexpr_string)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_USE_CXX11_ABI && _GLIBCXX_HOSTED && (defined(__glibcxx_is_constant_evaluated))
>  #  define __glibcxx_constexpr_string 201907L
> @@ -1476,7 +1487,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_string) && defined(__glibcxx_want_constexpr_string) */
>  #undef __glibcxx_want_constexpr_string
>
> -// from version.def line 1223
> +// from version.def line 1232
>  #if !defined(__cpp_lib_constexpr_vector)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_constexpr_vector 201907L
> @@ -1487,7 +1498,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_vector) && defined(__glibcxx_want_constexpr_vector) */
>  #undef __glibcxx_want_constexpr_vector
>
> -// from version.def line 1232
> +// from version.def line 1241
>  #if !defined(__cpp_lib_erase_if)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_erase_if 202002L
> @@ -1498,7 +1509,7 @@
>  #endif /* !defined(__cpp_lib_erase_if) && defined(__glibcxx_want_erase_if) */
>  #undef __glibcxx_want_erase_if
>
> -// from version.def line 1241
> +// from version.def line 1250
>  #if !defined(__cpp_lib_generic_unordered_lookup)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_generic_unordered_lookup 201811L
> @@ -1509,7 +1520,7 @@
>  #endif /* !defined(__cpp_lib_generic_unordered_lookup) && defined(__glibcxx_want_generic_unordered_lookup) */
>  #undef __glibcxx_want_generic_unordered_lookup
>
> -// from version.def line 1250
> +// from version.def line 1259
>  #if !defined(__cpp_lib_jthread)
>  # if (__cplusplus >= 202002L) && defined(_GLIBCXX_HAS_GTHREADS) && _GLIBCXX_HOSTED
>  #  define __glibcxx_jthread 201911L
> @@ -1520,7 +1531,7 @@
>  #endif /* !defined(__cpp_lib_jthread) && defined(__glibcxx_want_jthread) */
>  #undef __glibcxx_want_jthread
>
> -// from version.def line 1260
> +// from version.def line 1269
>  #if !defined(__cpp_lib_latch)
>  # if (__cplusplus >= 202002L) && (__glibcxx_atomic_wait)
>  #  define __glibcxx_latch 201907L
> @@ -1531,7 +1542,7 @@
>  #endif /* !defined(__cpp_lib_latch) && defined(__glibcxx_want_latch) */
>  #undef __glibcxx_want_latch
>
> -// from version.def line 1269
> +// from version.def line 1278
>  #if !defined(__cpp_lib_list_remove_return_type)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_list_remove_return_type 201806L
> @@ -1542,7 +1553,7 @@
>  #endif /* !defined(__cpp_lib_list_remove_return_type) && defined(__glibcxx_want_list_remove_return_type) */
>  #undef __glibcxx_want_list_remove_return_type
>
> -// from version.def line 1278
> +// from version.def line 1287
>  #if !defined(__cpp_lib_polymorphic_allocator)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_polymorphic_allocator 201902L
> @@ -1553,7 +1564,7 @@
>  #endif /* !defined(__cpp_lib_polymorphic_allocator) && defined(__glibcxx_want_polymorphic_allocator) */
>  #undef __glibcxx_want_polymorphic_allocator
>
> -// from version.def line 1287
> +// from version.def line 1296
>  #if !defined(__cpp_lib_move_iterator_concept)
>  # if (__cplusplus >= 202002L) && (__glibcxx_concepts)
>  #  define __glibcxx_move_iterator_concept 202207L
> @@ -1564,7 +1575,7 @@
>  #endif /* !defined(__cpp_lib_move_iterator_concept) && defined(__glibcxx_want_move_iterator_concept) */
>  #undef __glibcxx_want_move_iterator_concept
>
> -// from version.def line 1297
> +// from version.def line 1306
>  #if !defined(__cpp_lib_semaphore)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED && (__glibcxx_atomic_wait || _GLIBCXX_HAVE_POSIX_SEMAPHORE)
>  #  define __glibcxx_semaphore 201907L
> @@ -1575,7 +1586,7 @@
>  #endif /* !defined(__cpp_lib_semaphore) && defined(__glibcxx_want_semaphore) */
>  #undef __glibcxx_want_semaphore
>
> -// from version.def line 1307
> +// from version.def line 1316
>  #if !defined(__cpp_lib_smart_ptr_for_overwrite)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_smart_ptr_for_overwrite 202002L
> @@ -1586,7 +1597,7 @@
>  #endif /* !defined(__cpp_lib_smart_ptr_for_overwrite) && defined(__glibcxx_want_smart_ptr_for_overwrite) */
>  #undef __glibcxx_want_smart_ptr_for_overwrite
>
> -// from version.def line 1316
> +// from version.def line 1325
>  #if !defined(__cpp_lib_syncbuf)
>  # if (__cplusplus >= 202002L) && _GLIBCXX_USE_CXX11_ABI && _GLIBCXX_HOSTED
>  #  define __glibcxx_syncbuf 201803L
> @@ -1597,7 +1608,7 @@
>  #endif /* !defined(__cpp_lib_syncbuf) && defined(__glibcxx_want_syncbuf) */
>  #undef __glibcxx_want_syncbuf
>
> -// from version.def line 1326
> +// from version.def line 1335
>  #if !defined(__cpp_lib_byteswap)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_byteswap 202110L
> @@ -1608,7 +1619,7 @@
>  #endif /* !defined(__cpp_lib_byteswap) && defined(__glibcxx_want_byteswap) */
>  #undef __glibcxx_want_byteswap
>
> -// from version.def line 1334
> +// from version.def line 1343
>  #if !defined(__cpp_lib_constexpr_charconv)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_constexpr_charconv 202207L
> @@ -1619,7 +1630,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_charconv) && defined(__glibcxx_want_constexpr_charconv) */
>  #undef __glibcxx_want_constexpr_charconv
>
> -// from version.def line 1342
> +// from version.def line 1351
>  #if !defined(__cpp_lib_constexpr_typeinfo)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_constexpr_typeinfo 202106L
> @@ -1630,7 +1641,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_typeinfo) && defined(__glibcxx_want_constexpr_typeinfo) */
>  #undef __glibcxx_want_constexpr_typeinfo
>
> -// from version.def line 1350
> +// from version.def line 1359
>  #if !defined(__cpp_lib_expected)
>  # if (__cplusplus >= 202100L) && (__cpp_concepts >= 202002L)
>  #  define __glibcxx_expected 202211L
> @@ -1641,7 +1652,7 @@
>  #endif /* !defined(__cpp_lib_expected) && defined(__glibcxx_want_expected) */
>  #undef __glibcxx_want_expected
>
> -// from version.def line 1359
> +// from version.def line 1368
>  #if !defined(__cpp_lib_freestanding_algorithm)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_algorithm 202311L
> @@ -1652,7 +1663,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_algorithm) && defined(__glibcxx_want_freestanding_algorithm) */
>  #undef __glibcxx_want_freestanding_algorithm
>
> -// from version.def line 1368
> +// from version.def line 1377
>  #if !defined(__cpp_lib_freestanding_array)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_array 202311L
> @@ -1663,7 +1674,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_array) && defined(__glibcxx_want_freestanding_array) */
>  #undef __glibcxx_want_freestanding_array
>
> -// from version.def line 1377
> +// from version.def line 1386
>  #if !defined(__cpp_lib_freestanding_cstring)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_cstring 202311L
> @@ -1674,7 +1685,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_cstring) && defined(__glibcxx_want_freestanding_cstring) */
>  #undef __glibcxx_want_freestanding_cstring
>
> -// from version.def line 1386
> +// from version.def line 1395
>  #if !defined(__cpp_lib_freestanding_expected)
>  # if (__cplusplus >= 202100L) && (__cpp_lib_expected)
>  #  define __glibcxx_freestanding_expected 202311L
> @@ -1685,7 +1696,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_expected) && defined(__glibcxx_want_freestanding_expected) */
>  #undef __glibcxx_want_freestanding_expected
>
> -// from version.def line 1396
> +// from version.def line 1405
>  #if !defined(__cpp_lib_freestanding_optional)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_optional 202311L
> @@ -1696,7 +1707,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_optional) && defined(__glibcxx_want_freestanding_optional) */
>  #undef __glibcxx_want_freestanding_optional
>
> -// from version.def line 1405
> +// from version.def line 1414
>  #if !defined(__cpp_lib_freestanding_string_view)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_string_view 202311L
> @@ -1707,7 +1718,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_string_view) && defined(__glibcxx_want_freestanding_string_view) */
>  #undef __glibcxx_want_freestanding_string_view
>
> -// from version.def line 1414
> +// from version.def line 1423
>  #if !defined(__cpp_lib_freestanding_variant)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_freestanding_variant 202311L
> @@ -1718,7 +1729,7 @@
>  #endif /* !defined(__cpp_lib_freestanding_variant) && defined(__glibcxx_want_freestanding_variant) */
>  #undef __glibcxx_want_freestanding_variant
>
> -// from version.def line 1423
> +// from version.def line 1432
>  #if !defined(__cpp_lib_invoke_r)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_invoke_r 202106L
> @@ -1729,7 +1740,7 @@
>  #endif /* !defined(__cpp_lib_invoke_r) && defined(__glibcxx_want_invoke_r) */
>  #undef __glibcxx_want_invoke_r
>
> -// from version.def line 1431
> +// from version.def line 1440
>  #if !defined(__cpp_lib_is_scoped_enum)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_is_scoped_enum 202011L
> @@ -1740,7 +1751,7 @@
>  #endif /* !defined(__cpp_lib_is_scoped_enum) && defined(__glibcxx_want_is_scoped_enum) */
>  #undef __glibcxx_want_is_scoped_enum
>
> -// from version.def line 1439
> +// from version.def line 1448
>  #if !defined(__cpp_lib_reference_from_temporary)
>  # if (__cplusplus >= 202100L) && (__has_builtin(__reference_constructs_from_temporary) && __has_builtin(__reference_converts_from_temporary))
>  #  define __glibcxx_reference_from_temporary 202202L
> @@ -1751,7 +1762,7 @@
>  #endif /* !defined(__cpp_lib_reference_from_temporary) && defined(__glibcxx_want_reference_from_temporary) */
>  #undef __glibcxx_want_reference_from_temporary
>
> -// from version.def line 1459
> +// from version.def line 1468
>  #if !defined(__cpp_lib_ranges_to_container)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_ranges_to_container 202202L
> @@ -1762,7 +1773,7 @@
>  #endif /* !defined(__cpp_lib_ranges_to_container) && defined(__glibcxx_want_ranges_to_container) */
>  #undef __glibcxx_want_ranges_to_container
>
> -// from version.def line 1468
> +// from version.def line 1477
>  #if !defined(__cpp_lib_ranges_zip)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_zip 202110L
> @@ -1773,7 +1784,7 @@
>  #endif /* !defined(__cpp_lib_ranges_zip) && defined(__glibcxx_want_ranges_zip) */
>  #undef __glibcxx_want_ranges_zip
>
> -// from version.def line 1476
> +// from version.def line 1485
>  #if !defined(__cpp_lib_ranges_chunk)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_chunk 202202L
> @@ -1784,7 +1795,7 @@
>  #endif /* !defined(__cpp_lib_ranges_chunk) && defined(__glibcxx_want_ranges_chunk) */
>  #undef __glibcxx_want_ranges_chunk
>
> -// from version.def line 1484
> +// from version.def line 1493
>  #if !defined(__cpp_lib_ranges_slide)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_slide 202202L
> @@ -1795,7 +1806,7 @@
>  #endif /* !defined(__cpp_lib_ranges_slide) && defined(__glibcxx_want_ranges_slide) */
>  #undef __glibcxx_want_ranges_slide
>
> -// from version.def line 1492
> +// from version.def line 1501
>  #if !defined(__cpp_lib_ranges_chunk_by)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_chunk_by 202202L
> @@ -1806,7 +1817,7 @@
>  #endif /* !defined(__cpp_lib_ranges_chunk_by) && defined(__glibcxx_want_ranges_chunk_by) */
>  #undef __glibcxx_want_ranges_chunk_by
>
> -// from version.def line 1500
> +// from version.def line 1509
>  #if !defined(__cpp_lib_ranges_join_with)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_join_with 202202L
> @@ -1817,7 +1828,7 @@
>  #endif /* !defined(__cpp_lib_ranges_join_with) && defined(__glibcxx_want_ranges_join_with) */
>  #undef __glibcxx_want_ranges_join_with
>
> -// from version.def line 1508
> +// from version.def line 1517
>  #if !defined(__cpp_lib_ranges_repeat)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_repeat 202207L
> @@ -1828,7 +1839,7 @@
>  #endif /* !defined(__cpp_lib_ranges_repeat) && defined(__glibcxx_want_ranges_repeat) */
>  #undef __glibcxx_want_ranges_repeat
>
> -// from version.def line 1516
> +// from version.def line 1525
>  #if !defined(__cpp_lib_ranges_stride)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_stride 202207L
> @@ -1839,7 +1850,7 @@
>  #endif /* !defined(__cpp_lib_ranges_stride) && defined(__glibcxx_want_ranges_stride) */
>  #undef __glibcxx_want_ranges_stride
>
> -// from version.def line 1524
> +// from version.def line 1533
>  #if !defined(__cpp_lib_ranges_cartesian_product)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_cartesian_product 202207L
> @@ -1850,7 +1861,7 @@
>  #endif /* !defined(__cpp_lib_ranges_cartesian_product) && defined(__glibcxx_want_ranges_cartesian_product) */
>  #undef __glibcxx_want_ranges_cartesian_product
>
> -// from version.def line 1532
> +// from version.def line 1541
>  #if !defined(__cpp_lib_ranges_as_rvalue)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_as_rvalue 202207L
> @@ -1861,7 +1872,7 @@
>  #endif /* !defined(__cpp_lib_ranges_as_rvalue) && defined(__glibcxx_want_ranges_as_rvalue) */
>  #undef __glibcxx_want_ranges_as_rvalue
>
> -// from version.def line 1540
> +// from version.def line 1549
>  #if !defined(__cpp_lib_ranges_as_const)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_as_const 202207L
> @@ -1872,7 +1883,7 @@
>  #endif /* !defined(__cpp_lib_ranges_as_const) && defined(__glibcxx_want_ranges_as_const) */
>  #undef __glibcxx_want_ranges_as_const
>
> -// from version.def line 1548
> +// from version.def line 1557
>  #if !defined(__cpp_lib_ranges_enumerate)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_enumerate 202302L
> @@ -1883,7 +1894,7 @@
>  #endif /* !defined(__cpp_lib_ranges_enumerate) && defined(__glibcxx_want_ranges_enumerate) */
>  #undef __glibcxx_want_ranges_enumerate
>
> -// from version.def line 1556
> +// from version.def line 1565
>  #if !defined(__cpp_lib_ranges_fold)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_fold 202207L
> @@ -1894,7 +1905,7 @@
>  #endif /* !defined(__cpp_lib_ranges_fold) && defined(__glibcxx_want_ranges_fold) */
>  #undef __glibcxx_want_ranges_fold
>
> -// from version.def line 1564
> +// from version.def line 1573
>  #if !defined(__cpp_lib_ranges_contains)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_contains 202207L
> @@ -1905,7 +1916,7 @@
>  #endif /* !defined(__cpp_lib_ranges_contains) && defined(__glibcxx_want_ranges_contains) */
>  #undef __glibcxx_want_ranges_contains
>
> -// from version.def line 1572
> +// from version.def line 1581
>  #if !defined(__cpp_lib_ranges_iota)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_iota 202202L
> @@ -1916,7 +1927,7 @@
>  #endif /* !defined(__cpp_lib_ranges_iota) && defined(__glibcxx_want_ranges_iota) */
>  #undef __glibcxx_want_ranges_iota
>
> -// from version.def line 1580
> +// from version.def line 1589
>  #if !defined(__cpp_lib_ranges_find_last)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_ranges_find_last 202207L
> @@ -1927,7 +1938,7 @@
>  #endif /* !defined(__cpp_lib_ranges_find_last) && defined(__glibcxx_want_ranges_find_last) */
>  #undef __glibcxx_want_ranges_find_last
>
> -// from version.def line 1588
> +// from version.def line 1597
>  #if !defined(__cpp_lib_constexpr_bitset)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED && (__cpp_constexpr_dynamic_alloc)
>  #  define __glibcxx_constexpr_bitset 202202L
> @@ -1938,7 +1949,7 @@
>  #endif /* !defined(__cpp_lib_constexpr_bitset) && defined(__glibcxx_want_constexpr_bitset) */
>  #undef __glibcxx_want_constexpr_bitset
>
> -// from version.def line 1598
> +// from version.def line 1607
>  #if !defined(__cpp_lib_stdatomic_h)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_stdatomic_h 202011L
> @@ -1949,7 +1960,7 @@
>  #endif /* !defined(__cpp_lib_stdatomic_h) && defined(__glibcxx_want_stdatomic_h) */
>  #undef __glibcxx_want_stdatomic_h
>
> -// from version.def line 1606
> +// from version.def line 1615
>  #if !defined(__cpp_lib_adaptor_iterator_pair_constructor)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_adaptor_iterator_pair_constructor 202106L
> @@ -1960,7 +1971,7 @@
>  #endif /* !defined(__cpp_lib_adaptor_iterator_pair_constructor) && defined(__glibcxx_want_adaptor_iterator_pair_constructor) */
>  #undef __glibcxx_want_adaptor_iterator_pair_constructor
>
> -// from version.def line 1615
> +// from version.def line 1624
>  #if !defined(__cpp_lib_formatters)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_formatters 202302L
> @@ -1971,7 +1982,7 @@
>  #endif /* !defined(__cpp_lib_formatters) && defined(__glibcxx_want_formatters) */
>  #undef __glibcxx_want_formatters
>
> -// from version.def line 1624
> +// from version.def line 1633
>  #if !defined(__cpp_lib_forward_like)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_forward_like 202207L
> @@ -1982,7 +1993,7 @@
>  #endif /* !defined(__cpp_lib_forward_like) && defined(__glibcxx_want_forward_like) */
>  #undef __glibcxx_want_forward_like
>
> -// from version.def line 1632
> +// from version.def line 1641
>  #if !defined(__cpp_lib_ios_noreplace)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_ios_noreplace 202207L
> @@ -1993,7 +2004,7 @@
>  #endif /* !defined(__cpp_lib_ios_noreplace) && defined(__glibcxx_want_ios_noreplace) */
>  #undef __glibcxx_want_ios_noreplace
>
> -// from version.def line 1641
> +// from version.def line 1650
>  #if !defined(__cpp_lib_move_only_function)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_move_only_function 202110L
> @@ -2004,7 +2015,7 @@
>  #endif /* !defined(__cpp_lib_move_only_function) && defined(__glibcxx_want_move_only_function) */
>  #undef __glibcxx_want_move_only_function
>
> -// from version.def line 1650
> +// from version.def line 1659
>  #if !defined(__cpp_lib_out_ptr)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_out_ptr 202311L
> @@ -2015,7 +2026,7 @@
>  #endif /* !defined(__cpp_lib_out_ptr) && defined(__glibcxx_want_out_ptr) */
>  #undef __glibcxx_want_out_ptr
>
> -// from version.def line 1658
> +// from version.def line 1667
>  #if !defined(__cpp_lib_print)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_print 202211L
> @@ -2026,7 +2037,7 @@
>  #endif /* !defined(__cpp_lib_print) && defined(__glibcxx_want_print) */
>  #undef __glibcxx_want_print
>
> -// from version.def line 1667
> +// from version.def line 1676
>  #if !defined(__cpp_lib_spanstream)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED && (__glibcxx_span)
>  #  define __glibcxx_spanstream 202106L
> @@ -2037,7 +2048,7 @@
>  #endif /* !defined(__cpp_lib_spanstream) && defined(__glibcxx_want_spanstream) */
>  #undef __glibcxx_want_spanstream
>
> -// from version.def line 1677
> +// from version.def line 1686
>  #if !defined(__cpp_lib_stacktrace)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED && (_GLIBCXX_HAVE_STACKTRACE)
>  #  define __glibcxx_stacktrace 202011L
> @@ -2048,7 +2059,7 @@
>  #endif /* !defined(__cpp_lib_stacktrace) && defined(__glibcxx_want_stacktrace) */
>  #undef __glibcxx_want_stacktrace
>
> -// from version.def line 1687
> +// from version.def line 1696
>  #if !defined(__cpp_lib_string_contains)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_string_contains 202011L
> @@ -2059,7 +2070,7 @@
>  #endif /* !defined(__cpp_lib_string_contains) && defined(__glibcxx_want_string_contains) */
>  #undef __glibcxx_want_string_contains
>
> -// from version.def line 1696
> +// from version.def line 1705
>  #if !defined(__cpp_lib_string_resize_and_overwrite)
>  # if (__cplusplus >= 202100L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_string_resize_and_overwrite 202110L
> @@ -2070,7 +2081,7 @@
>  #endif /* !defined(__cpp_lib_string_resize_and_overwrite) && defined(__glibcxx_want_string_resize_and_overwrite) */
>  #undef __glibcxx_want_string_resize_and_overwrite
>
> -// from version.def line 1705
> +// from version.def line 1714
>  #if !defined(__cpp_lib_to_underlying)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_to_underlying 202102L
> @@ -2081,7 +2092,7 @@
>  #endif /* !defined(__cpp_lib_to_underlying) && defined(__glibcxx_want_to_underlying) */
>  #undef __glibcxx_want_to_underlying
>
> -// from version.def line 1713
> +// from version.def line 1722
>  #if !defined(__cpp_lib_unreachable)
>  # if (__cplusplus >= 202100L)
>  #  define __glibcxx_unreachable 202202L
> @@ -2092,7 +2103,7 @@
>  #endif /* !defined(__cpp_lib_unreachable) && defined(__glibcxx_want_unreachable) */
>  #undef __glibcxx_want_unreachable
>
> -// from version.def line 1721
> +// from version.def line 1730
>  #if !defined(__cpp_lib_fstream_native_handle)
>  # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED
>  #  define __glibcxx_fstream_native_handle 202306L
> @@ -2103,7 +2114,7 @@
>  #endif /* !defined(__cpp_lib_fstream_native_handle) && defined(__glibcxx_want_fstream_native_handle) */
>  #undef __glibcxx_want_fstream_native_handle
>
> -// from version.def line 1730
> +// from version.def line 1739
>  #if !defined(__cpp_lib_ratio)
>  # if (__cplusplus >  202302L)
>  #  define __glibcxx_ratio 202306L
> @@ -2114,7 +2125,7 @@
>  #endif /* !defined(__cpp_lib_ratio) && defined(__glibcxx_want_ratio) */
>  #undef __glibcxx_want_ratio
>
> -// from version.def line 1738
> +// from version.def line 1747
>  #if !defined(__cpp_lib_saturation_arithmetic)
>  # if (__cplusplus >  202302L)
>  #  define __glibcxx_saturation_arithmetic 202311L
> @@ -2125,7 +2136,7 @@
>  #endif /* !defined(__cpp_lib_saturation_arithmetic) && defined(__glibcxx_want_saturation_arithmetic) */
>  #undef __glibcxx_want_saturation_arithmetic
>
> -// from version.def line 1746
> +// from version.def line 1755
>  #if !defined(__cpp_lib_to_string)
>  # if (__cplusplus >  202302L) && _GLIBCXX_HOSTED && (__glibcxx_to_chars)
>  #  define __glibcxx_to_string 202306L
> @@ -2136,7 +2147,7 @@
>  #endif /* !defined(__cpp_lib_to_string) && defined(__glibcxx_want_to_string) */
>  #undef __glibcxx_want_to_string
>
> -// from version.def line 1756
> +// from version.def line 1765
>  #if !defined(__cpp_lib_generator)
>  # if (__cplusplus >= 202100L) && (__glibcxx_coroutine)
>  #  define __glibcxx_generator 202207L
> diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional
> index 190cea612bb..87a2ed28e3b 100644
> --- a/libstdc++-v3/include/std/functional
> +++ b/libstdc++-v3/include/std/functional
> @@ -76,6 +76,7 @@
>
>  #define __glibcxx_want_boyer_moore_searcher
>  #define __glibcxx_want_bind_front
> +#define __glibcxx_want_bind_back
>  #define __glibcxx_want_constexpr_functional
>  #define __glibcxx_want_invoke
>  #define __glibcxx_want_invoke_r
> @@ -1046,6 +1047,76 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      }
>  #endif // __cpp_lib_bind_front
>
> +#ifdef __cpp_lib_bind_back // C++ >= 23
> +  template<typename _Fd, typename... _BoundArgs>
> +    struct _Bind_back
> +    {
> +      static_assert(is_move_constructible_v<_Fd>);
> +      static_assert((is_move_constructible_v<_BoundArgs> && ...));
> +
> +      // First parameter is to ensure this constructor is never used
> +      // instead of the copy/move constructor.
> +      template<typename _Fn, typename... _Args>
> +       explicit constexpr
> +       _Bind_back(int, _Fn&& __fn, _Args&&... __args)
> +       noexcept(__and_<is_nothrow_constructible<_Fd, _Fn>,
> +                       is_nothrow_constructible<_BoundArgs, _Args>...>::value)
> +       : _M_fd(std::forward<_Fn>(__fn)),
> +         _M_bound_args(std::forward<_Args>(__args)...)
> +       { static_assert(sizeof...(_Args) == sizeof...(_BoundArgs)); }
> +
> +      template<typename _Self, typename... _CallArgs>
> +       constexpr
> +       invoke_result_t<__like_t<_Self, _Fd>, _CallArgs..., __like_t<_Self, _BoundArgs>...>
> +       operator()(this _Self&& __self, _CallArgs&&... __call_args)
> +       noexcept(is_nothrow_invocable_v<__like_t<_Self, _Fd>,
> +                                       _CallArgs...,
> +                                       __like_t<_Self, _BoundArgs>...>)
> +       {
> +         return _S_call(std::forward<_Self>(__self), _BoundIndices(),
> +                        std::forward<_CallArgs>(__call_args)...);
> +       }
> +
> +    private:
> +      using _BoundIndices = index_sequence_for<_BoundArgs...>;
> +
> +      template<typename _Tp, size_t... _Ind, typename... _CallArgs>
> +       static constexpr
> +       decltype(auto)
> +       _S_call(_Tp&& __g, index_sequence<_Ind...>, _CallArgs&&... __call_args)
> +       {
> +         return std::invoke(std::forward<_Tp>(__g)._M_fd,
> +             std::forward<_CallArgs>(__call_args)...,
> +             std::get<_Ind>(std::forward<_Tp>(__g)._M_bound_args)...);
> +       }
> +
> +      [[no_unique_address]] _Fd _M_fd;
> +      [[no_unique_address]] std::tuple<_BoundArgs...> _M_bound_args;
> +    };
> +
> +  template<typename _Fn, typename... _Args>
> +    using _Bind_back_t = _Bind_back<decay_t<_Fn>, decay_t<_Args>...>;
> +
> +  /** Create call wrapper by partial application of arguments to function.
> +   *
> +   * The result of `std::bind_back(f, args...)` is a function object that
> +   * stores `f` and the bound arguments, `args...`. When that function
> +   * object is invoked with `call_args...` it returns the result of calling
> +   * `f(call_args..., args...)`.
> +   *
> +   *  @since C++23
> +   */
> +  template<typename _Fn, typename... _Args>
> +    constexpr _Bind_back_t<_Fn, _Args...>
> +    bind_back(_Fn&& __fn, _Args&&... __args)
> +    noexcept(is_nothrow_constructible_v<_Bind_back_t<_Fn, _Args...>,
> +                                       int, _Fn, _Args...>)
> +    {
> +      return _Bind_back_t<_Fn, _Args...>(0, std::forward<_Fn>(__fn),
> +                                        std::forward<_Args>(__args)...);
> +    }
> +#endif
> +
>  #if __cplusplus >= 201402L
>    /// Generalized negator.
>    template<typename _Fn>
> diff --git a/libstdc++-v3/testsuite/20_util/function_objects/bind_back/1.cc b/libstdc++-v3/testsuite/20_util/function_objects/bind_back/1.cc
> new file mode 100644
> index 00000000000..ec66e2a3381
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/20_util/function_objects/bind_back/1.cc
> @@ -0,0 +1,178 @@
> +// Copyright (C) 2014-2024 Free Software Foundation, Inc.
> +//
> +// This file is part of the GNU ISO C++ Library.  This library is free
> +// software; you can redistribute it and/or modify it under the
> +// terms of the GNU General Public License as published by the
> +// Free Software Foundation; either version 3, or (at your option)
> +// any later version.
> +
> +// This library is distributed in the hope that it will be useful,
> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +// GNU General Public License for more details.
> +
> +// You should have received a copy of the GNU General Public License along
> +// with this library; see the file COPYING3.  If not see
> +// <http://www.gnu.org/licenses/>.
> +
> +// { dg-do run { target c++23 } }
> +// { dg-add-options no_pch }
> +
> +#include <functional>
> +
> +#ifndef __cpp_lib_bind_back
> +# error "Feature test macro for bind_back is missing in <functional>"
> +#elif __cpp_lib_bind_back < 202202L
> +# error "Feature test macro for bind_back has wrong value in <functional>"
> +#endif
> +
> +#include <testsuite_hooks.h>
> +
> +using std::bind_back;
> +using std::is_same_v;
> +using std::is_invocable_v;
> +using std::is_invocable_r_v;
> +
> +void
> +test01()
> +{
> +  struct F { void operator()() {} };
> +
> +  // Arguments should be decayed:
> +  static_assert(std::is_same_v<
> +      decltype(bind_back(std::declval<F>(), std::declval<int>())),
> +      decltype(bind_back(std::declval<F&>(), std::declval<int&>()))
> +      >);
> +  static_assert(std::is_same_v<
> +      decltype(bind_back(std::declval<F>(), std::declval<int>())),
> +      decltype(bind_back(std::declval<const F&>(), std::declval<const int&>()))
> +      >);
> +
> +  // Reference wrappers should be handled:
> +  static_assert(!std::is_same_v<
> +      decltype(bind_back(std::declval<F>(), std::declval<int&>())),
> +      decltype(bind_back(std::declval<F>(), std::ref(std::declval<int&>())))
> +      >);
> +  static_assert(!std::is_same_v<
> +      decltype(bind_back(std::declval<F>(), std::declval<const int&>())),
> +      decltype(bind_back(std::declval<F>(), std::cref(std::declval<int&>())))
> +      >);
> +  static_assert(!std::is_same_v<
> +      decltype(bind_back(std::declval<F>(), std::ref(std::declval<int&>()))),
> +      decltype(bind_back(std::declval<F>(), std::cref(std::declval<int&>())))
> +      >);
> +}
> +
> +void
> +test02()
> +{
> +  struct quals
> +  {
> +    bool as_const;
> +    bool as_lvalue;
> +  };
> +
> +  struct F
> +  {
> +    quals operator()() & { return { false, true }; }
> +    quals operator()() const & { return { true, true }; }
> +    quals operator()() && { return { false, false }; }
> +    quals operator()() const && { return { true, false }; }
> +  };
> +
> +  F f;
> +  auto g = bind_back(f);
> +  const auto& cg = g;
> +  quals q;
> +
> +  // constness and value category should be forwarded to the target object:
> +  q = g();
> +  VERIFY( ! q.as_const && q.as_lvalue );
> +  q = std::move(g)();
> +  VERIFY( ! q.as_const && ! q.as_lvalue );
> +  q = cg();
> +  VERIFY( q.as_const && q.as_lvalue );
> +  q = std::move(cg)();
> +  VERIFY( q.as_const && ! q.as_lvalue );
> +}
> +
> +void
> +test03()
> +{
> +  struct F
> +  {
> +    int& operator()(void*, int& i) { return i; }
> +    void* operator()(void* p, int) const { return p; }
> +  };
> +
> +  int i = 5;
> +  void* vp = &vp; // arbitrary void* value
> +
> +  auto g1 = bind_back(F{}, i); // call wrapper has bound arg of type int
> +  using G1 = decltype(g1);
> +  // Invoking G1& will pass g1's bound arg as int&, so calls first overload:
> +  static_assert(is_invocable_r_v<int&, G1&, void*>);
> +  // Invoking const G1& or G&& calls second overload:
> +  static_assert(is_invocable_r_v<void*, const G1&, void*>);
> +  static_assert(is_invocable_r_v<void*, G1&&, void*>);
> +  void* p1 = static_cast<G1&&>(g1)(vp);
> +  VERIFY( p1 == vp );
> +
> +  auto g2 = bind_back(F{}, std::ref(i)); // bound arg of type int&
> +  using G2 = decltype(g2);
> +  // Bound arg always forwarded as int& even from G2&& or const G2&
> +  static_assert(is_invocable_r_v<int&, G2&, void*>);
> +  static_assert(is_invocable_r_v<int&, G2&&, void*>);
> +  // But cannot call first overload on const G2:
> +  static_assert(is_invocable_r_v<void*, const G2&, void*>);
> +  static_assert(is_invocable_r_v<void*, const G2&&, void*>);
> +  int& i2 = g2(vp);
> +  VERIFY( &i2 == &i );
> +  int& i2r = static_cast<G2&&>(g2)(vp);
> +  VERIFY( &i2r == &i );
> +  void* p2 = const_cast<const G2&>(g2)(vp);
> +  VERIFY( p2 == vp );
> +
> +  auto g3 = bind_back(F{}, std::cref(i)); // bound arg of type const int&
> +  using G3 = decltype(g3);
> +  // Bound arg always forwarded as const int& so can only call second overload:
> +  static_assert(is_invocable_r_v<void*, G3&, void*>);
> +  static_assert(is_invocable_r_v<void*, G3&&, void*>);
> +  static_assert(is_invocable_r_v<void*, const G3&, void*>);
> +  static_assert(is_invocable_r_v<void*, const G3&&, void*>);
> +
> +  auto g4 = bind_back(g2, nullptr);
> +  using G4 = decltype(g4);
> +  static_assert(is_invocable_r_v<int&, G4&>);
> +  static_assert(is_invocable_r_v<int&, G4&&>);
> +  static_assert(is_invocable_r_v<void*, const G4&>);
> +  static_assert(is_invocable_r_v<void*, const G4&&>);
> +}
> +
> +constexpr int f(int i, int j, int k) { return i + 2*(j + k); }
> +
> +constexpr bool
> +test04()
> +{
> +  auto g = bind_back(f);
> +  VERIFY( g(1, 2, 3) == 1 + 2*(2 + 3) );
> +  auto g1 = bind_back(f, 1);
> +  VERIFY( g1(2, 3) == 2 + 2*(3 + 1) );
> +  VERIFY( bind_back(g, 1)(2, 3) == 2 + 2*(3 + 1) );
> +  auto g2 = bind_back(f, 1, 2);
> +  VERIFY( g2(3) == 3 + 2*(1 + 2) );
> +  VERIFY( bind_back(g1, 2)(3) == 3 + 2*(2 + 1) );
> +  auto g3 = bind_back(f, 1, 2, 3);
> +  VERIFY( g3() == 1 + 2*(2 + 3) );
> +  VERIFY( bind_back(g2, 3)() == 3 + 2*(1 + 2) );
> +  return true;
> +}
> +
> +int
> +main()
> +{
> +  test01();
> +  test02();
> +  test03();
> +  static_assert(test04());
> +}
> diff --git a/libstdc++-v3/testsuite/20_util/function_objects/bind_back/111327.cc b/libstdc++-v3/testsuite/20_util/function_objects/bind_back/111327.cc
> new file mode 100644
> index 00000000000..d634db9dc1d
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/20_util/function_objects/bind_back/111327.cc
> @@ -0,0 +1,42 @@
> +// PR libstdc++/111327 - std::bind_front (and std::not_fn) doesn't always
> +// perfectly forward according to value category of the call wrapper object
> +// { dg-do compile { target c++23 } }
> +
> +#include <functional>
> +#include <utility>
> +
> +struct F {
> +  void operator()(...) & = delete;
> +  void operator()(...) const &;
> +};
> +
> +struct G {
> +  void operator()(...) && = delete;
> +  void operator()(...) const &&;
> +};
> +
> +int main() {
> +  auto f0 = std::bind_back(F{});
> +  f0(); // { dg-error "deleted|no match" }
> +  std::move(f0)();
> +  std::as_const(f0)();
> +  std::move(std::as_const(f0))();
> +
> +  auto g0 = std::bind_back(G{});
> +  g0(); // { dg-error "deleted|no match" }
> +  std::move(g0)(); // { dg-error "deleted|no match" }
> +  std::move(std::as_const(g0))();
> +
> +  auto f1 = std::bind_back(F{}, 42);
> +  f1(); // { dg-error "deleted|no match" }
> +  std::move(f1)();
> +  std::as_const(f1)();
> +  std::move(std::as_const(f1))();
> +
> +  auto g1 = std::bind_back(G{}, 42);
> +  g1(); // { dg-error "deleted|no match" }
> +  std::move(g1)(); // { dg-error "deleted|no match" }
> +  std::move(std::as_const(g1))();
> +}
> +
> +// { dg-error "no type named 'type' in 'struct std::invoke_result" "" { target c++23 } 0 }
> --
> 2.43.0.283.ga54a84b333
>