ISO C++ 2023 In this implementation the -std=gnu++23 or -std=c++23 flag must be used to enable language and library features. See dialect options. The pre-defined symbol __cplusplus is used to check for the presence of the required flag. This section describes the C++23 and library TS support in the GCC 14 release series. The following table lists new library features that have been accepted into the C++23 working draft. The "Proposal" column provides a link to the ISO C++ committee proposal that describes the feature, while the "Status" column indicates the first version of GCC that contains an implementation of this feature (if it has been implemented). A dash (—) in the status column indicates that the changes in the proposal either do not affect the code in libstdc++, or the changes are not required for conformance. The "SD-6 Feature Test / Notes" column shows the corresponding macro or header from SD-6: Feature-testing recommendations for C++ (where applicable) or any notes about the implementation. Library Feature Proposal Status SD-6 Feature Test / Notes Ranges and Views Range constructor for std::string_view P1989R2 11.1 join_view should join all views of ranges P2328R1 11.2 Clarifying range adaptor objects P2281R1 11.1 Views should not be required to be default constructible P2325R3 11.3 __cpp_lib_ranges >= 202106L Conditionally borrowed ranges P2017R1 11.1 Require span & basic_string_view to be Trivially Copyable P2251R1 Yes Repairing input range adaptors and counted_iterator P2259R1 12.1 Superior String Splitting P2210R2 12.1 What is a view? P2415R2 12.1 __cpp_lib_ranges >= 202110L Fix istream_view P2432R1 12.1 starts_with and ends_with P1659R3 __cpp_lib_ranges_starts_ends_with >= 202106L zip P2321R2 13.1 __cpp_lib_ranges_zip >= 202110L views::repeat P2474R2 13.1 __cpp_lib_ranges_repeat >= 202207L views::enumerate P2164R9 13.1 __cpp_lib_ranges_enumerate >= 202302L views::join_with P2441R2 13.1 __cpp_lib_ranges_join_with >= 202202L Windowing range adaptors: views::chunk and views::slide P2442R1 13.1 __cpp_lib_ranges_slide >= 202202L views::chunk_by P2443R1 13.1 __cpp_lib_ranges_chunk_by >= 202202L views::stride P1899R3 13.1 __cpp_lib_ranges_stride >= 202207L views::cartesian_product P2374R4 13.1 __cpp_lib_ranges_cartesian_product >= 202207L Empty Product for certain Views P2540R1 13.1 __cpp_lib_ranges_cartesian_product >= 202207L views::as_rvalue P2446R2 13.1 __cpp_lib_ranges_as_rvalue >= 202207L cbegin should always return a constant iterator P2278R4 13.1 __cpp_lib_ranges_as_const >= 202207L ranges::to P1206R7 14.1 (ranges::to function) __cpp_lib_containers_ranges >= 202202L, __cpp_lib_ranges_to_container >= 202202L Ranges iterators as inputs to non-Ranges algorithms P2408R5 __cpp_lib_algorithm_iterator_requirements >= 202207L Pipe support for user-defined range adaptors P2387R3 13.1 __cpp_lib_bind_pack >= 202202L, __cpp_lib_ranges >= 202202L ranges::iota, ranges::shift_left, and ranges::shift_right P2440R1 13.1 (ranges::iota) __cpp_lib_ranges_iota >= 202202L, __cpp_lib_shift >= 202202L ranges::find_last P1223R5 13.1 __cpp_lib_ranges_find_last >= 202207L ranges::contains P2302R4 13.1 __cpp_lib_ranges_contains >= 202207L Making multi-param constructors of views explicit P2711R1 ranges::fold P2322R6 13.1 __cpp_lib_ranges_fold >= 202207L Relaxing Ranges Just A Smidge P2609R3 14.3 __cpp_lib_ranges >= 202302L Compile-time programming A proposal for a type trait to detect scoped enumerations P1048R1 11.1 __cpp_lib_is_scoped_enum >= 202011L std::to_underlying for enumerations P1682R3 11.1 __cpp_lib_to_underlying >= 202102L Missing constexpr in std::optional and std::variant P2231R1 11.3 (optional) 12.1 (variant) __cpp_lib_constexpr_optional >= 202106L __cpp_lib_variant >= 202106L Making std::unique_ptr constexpr P2273R3 12.1 __cpp_lib_constexpr_memory >= 202202L Making std::type_info::operator== constexpr P1328R1 12.1 __cpp_lib_constexpr_typeinfo >= 202106L constexpr for <cmath> and <cstdlib> P0533R9 __cpp_lib_constexpr_cmath >= 202202L Deprecate std::aligned_storage and std::aligned_union P1413R3 13.1 A type trait to detect reference binding to temporary P2255R2 13.1 (missing changes to std::tuple) 14.1 (complete) __cpp_lib_reference_from_temporary >= 202202L Move-only types for equality_comparable_with, totally_ordered_with, and three_way_comparable_with P2404R3 __cpp_lib_concepts >= 202207L A trait for implicit lifetime types P2674R1 __cpp_lib_is_implicit_lifetime >= 202302L common_reference_t of reference_wrapper Should Be a Reference Type P2655R3 __cpp_lib_common_reference >= 202302L Deprecate numeric_limits::has_denorm P2614R2 Containers Iterator pair constructors for stack and queue P1425R4 12.1 __cpp_lib_adaptor_iterator_pair_constructor >= 202106L Stop overconstraining allocators in container deduction guides P1518R2 12.1 Heterogeneous erasure overloads for associative containers P2077R3 __cpp_lib_associative_heterogeneous_erasure >= 202110L <flat_map> P0429R9 __cpp_lib_flat_map >= 202207L <flat_set> P1222R4 __cpp_lib_flat_set >= 202207L mdspan P0009R18 __cpp_lib_mdspan >= 202207L index_type & size_type in mdspan P2599R2 __cpp_lib_mdspan >= 202207L mdspan: rename pointer and contiguous P2604R0 __cpp_lib_mdspan >= 202207L Add the missing empty to mdspan P2613R1 __cpp_lib_mdspan >= 202207L layout_stride static extents default constructor fix P2763R1 Strings and text string contains function P1679R3 11.1 __cpp_lib_string_contains >= 202011L Prohibit std::basic_string and std::basic_string_view construction from nullptr P2166R1 12.1 basic_string::resize_and_overwrite P1072R10 12.1 __cpp_lib_resize_and_overwrite >= 202110L A strstream replacement using span<charT> as buffer P0448R4 12.1 __cpp_lib_spanstream >= 202106L std::string::substr() && P2438R2 std::format improvements P2216R3 13.1 __cpp_lib_format >= 202106L Add support for std::generator-like types to std::format P2418R2 13.1 __cpp_lib_format >= 202110L Expose std::basic-format-string<charT, Args...> P2508R1 13.1 (feature test macro not updated) __cpp_lib_format >= 202207L Clarify handling of encodings in localized formatting of chrono types P2419R2 __cpp_lib_format >= 202207L Formatting pointers P2510R3 13.2 (feature test macro not defined) __cpp_lib_format >= 202207L Formatting Ranges P2286R8 __cpp_lib_format_ranges >= 202207L Improve default container formatting P2585R1 __cpp_lib_format_ranges >= 202207L Formatted output P2093R14 14.1 __cpp_lib_print >= 202207L Should the output of std::print to a terminal be synchronized with the underlying stream? P2539R3 14.1 Formatting thread::id and stacktrace P2693R1 14.1 __cpp_lib_formatters >= 202302L Add Constexpr Modifiers to Functions to_chars and from_chars for Integral Types in <charconv> Header P2291R3 13.1 __cpp_lib_constexpr_charconv >= 202207L Miscellaneous Inheriting from std::variant P2162R2 11.3 __cpp_lib_variant >= 202102L Printing volatile Pointers P1147R1 11.3 A Proposal to add stacktrace library P0881R7 12.1 __cpp_lib_stacktrace >= 202011L Add a pmr alias for std::stacktrace P2301R1 12.1 std::expected P0323R12 12.1 __cpp_lib_expected >= 202202L Monadic operations for std::expected P2505R5 13.1 __cpp_lib_expected >= 202211L Monadic operations for std::optional P0798R8 12.1 __cpp_lib_optional >= 202110L Compatibility between tuple, pair and tuple-like objects P2165R4 14.1 __cpp_lib_tuple_like >= 202207L Default Arguments for pair's Forwarding Constructor P1951R1 14.1 move_only_function P0288R9 12.1 __cpp_lib_move_only_function >= 202110L invoke_r P2136R3 12.1 __cpp_lib_invoke_r >= 202106L Byteswapping for fun&&nuf P1272R4 12.1 __cpp_lib_byteswap >= 202110L Function to mark unreachable code P0627R6 12.1 __cpp_lib_unreachable >= 202202L Add a conditional noexcept specification to std::exchange P2401R0 12.1 A more constexpr bitset P2417R2 13.1 __cpp_lib_constexpr_bitset >= 202207L Extended floating-point types and standard names P1467R9 13.1 Support C atomics in C++ P0943R6 12.1 __cpp_lib_stdatomic_h >= 202011L Clarifying the status of the "C headers" P2340R1 Yes Relax Requirements for time_point::clock P2212R2 Yes Removing Garbage Collection Support P2186R2 12.1 Easy [utilities], [ranges], and [iterators] P1642R11 13.1 Providing size feedback in the Allocator interface P0401R6 __cpp_lib_allocate_at_least >= 202306L Disallow User Specialization of allocator_traits P2652R2 Explicit lifetime management P2590R2 __cpp_lib_start_lifetime_as >= 202207L Fixing std::start_lifetime_as and std::start_lifetime_as_array P2679R2 out_ptr - a scalable output pointer abstraction P1132R8 14.1 __cpp_lib_out_ptr >= 202106L barrier's phase completion guarantees P2588R3 __cpp_lib_barrier >= 202302L Standard Library Modules std and std.compat P2465R3 __cpp_lib_modules >= 202207L