libc++ C++23 Status

Overview

In November 2020, the C++ standard committee adopted the first changes to the next version of the C++ standard, known here as “C++2b” (probably to be C++23). In February 2023, the C++ standard committee approved this draft, and sent it to ISO for approval as C++23.

This page shows the status of libc++; the status of clang’s support of the language features is here.

Attention

Features in unreleased drafts of the standard are subject to change.

The groups that have contributed papers:

• CWG - Core Language Working group

• LWG - Library working group

• SG1 - Study group #1 (Concurrency working group)

Note

“Nothing to do” means that no library changes were needed to implement this change.

Paper Status

Paper #	Group	Paper Name	Meeting	Status	First released version	Labels
P0881R7	LWG	A Proposal to add stacktrace library	Autumn 2020
P0943R6	LWG	Support C atomics in C++	Autumn 2020	Complete	15.0
P1048R1	LWG	A proposal for a type trait to detect scoped enumerations	Autumn 2020	Complete	12.0
P1679R3	LWG	string contains function	Autumn 2020	Complete	12.0
P1682R3	LWG	std::to_underlying for enumerations	February 2021	Complete	13.0
P2017R1	LWG	Conditionally borrowed ranges	February 2021	Complete	16.0	ranges
P2160R1	LWG	Locks lock lockables	February 2021
P2162R2	LWG	Inheriting from std::variant	February 2021	Complete	13.0
P2212R2	LWG	Relax Requirements for time_point::clock	February 2021
P2259R1	LWG	Repairing input range adaptors and counted_iterator	February 2021			ranges
P0401R6	LWG	Providing size feedback in the Allocator interface	June 2021	Complete	15.0
P0448R4	LWG	A strstream replacement using span<charT> as buffer	June 2021
P1132R8	LWG	out_ptr - a scalable output pointer abstraction	June 2021
P1328R1	LWG	Making std::type_info::operator== constexpr	June 2021	Complete	17.0
P1425R4	LWG	Iterators pair constructors for stack and queue	June 2021	Complete	14.0	ranges
P1518R2	LWG	Stop overconstraining allocators in container deduction guides	June 2021	Complete	13.0
P1659R3	LWG	starts_with and ends_with	June 2021			ranges
P1951R1	LWG	Default Arguments for pair Forwarding Constructor	June 2021	Complete	14.0
P1989R2	LWG	Range constructor for std::string_view	June 2021	Complete	14.0	ranges
P2136R3	LWG	invoke_r	June 2021	Complete	17.0
P2166R1	LWG	A Proposal to Prohibit std::basic_string and std::basic_string_view construction from nullptr	June 2021	Complete	13.0
P0288R9	LWG	any_invocable	October 2021
P0798R8	LWG	Monadic operations for std::optional	October 2021	Complete	14.0
P0849R8	LWG	auto(x): DECAY_COPY in the language	October 2021	Complete	14.0
P1072R10	LWG	basic_string::resize_and_overwrite	October 2021	Complete	14.0
P1147R1	LWG	Printing volatile Pointers	October 2021	Complete	14.0
P1272R4	LWG	Byteswapping for fun&&nuf	October 2021	Complete	14.0
P1675R2	LWG	rethrow_exception must be allowed to copy	October 2021
P2077R3	LWG	Heterogeneous erasure overloads for associative containers	October 2021
P2251R1	LWG	Require span & basic_string_view to be Trivially Copyable	October 2021	Complete	14.0
P2301R1	LWG	Add a pmr alias for std::stacktrace	October 2021
P2321R2	LWG	zip	October 2021	In Progress		ranges
P2340R1	LWG	Clarifying the status of the ‘C headers’	October 2021
P2393R1	LWG	Cleaning up integer-class types	October 2021
P2401R0	LWG	Add a conditional noexcept specification to std::exchange	October 2021	Complete	14.0
P0323R12	LWG	std::expected	February 2022	Complete	16.0
P0533R9	LWG	constexpr for <cmath> and <cstdlib>	February 2022	In Progress [1]
P0627R6	LWG	Function to mark unreachable code	February 2022	Complete	15.0
P1206R7	LWG	ranges::to: A function to convert any range to a container	February 2022	Complete	17.0	ranges
P1413R3	LWG	Deprecate std::aligned_storage and std::aligned_union	February 2022	Complete [2]
P2255R2	LWG	A type trait to detect reference binding to temporary	February 2022
P2273R3	LWG	Making std::unique_ptr constexpr	February 2022	Complete	16.0
P2387R3	LWG	Pipe support for user-defined range adaptors	February 2022			ranges
P2440R1	LWG	ranges::iota, ranges::shift_left and ranges::shift_right	February 2022			ranges
P2441R2	LWG	views::join_with	February 2022	In Progress		ranges
P2442R1	LWG	Windowing range adaptors: views::chunk and views::slide	February 2022			ranges
P2443R1	LWG	views::chunk_by	February 2022	Complete	18.0	ranges
P0009R18	LWG	mdspan: A Non-Owning Multidimensional Array Reference	July 2022	Complete	18.0
P0429R9	LWG	A Standard flat_map	July 2022
P1169R4	LWG	static operator()	July 2022	Complete	16.0
P1222R4	LWG	A Standard flat_set	July 2022
P1223R5	LWG	ranges::find_last(), ranges::find_last_if(), and ranges::find_last_if_not()	July 2022			ranges
P1467R9	LWG	Extended floating-point types and standard names	July 2022
P1642R11	LWG	Freestanding [utilities], [ranges], and [iterators]	July 2022
P1899R3	LWG	stride_view	July 2022			ranges
P2093R14	LWG	Formatted output	July 2022		Complete	18.0
P2165R4	LWG	Compatibility between tuple, pair and tuple-like objects	July 2022
P2278R4	LWG	cbegin should always return a constant iterator	July 2022			ranges
P2286R8	LWG	Formatting Ranges	July 2022	Complete	16.0	format ranges
P2291R3	LWG	Add Constexpr Modifiers to Functions to_chars and from_chars for Integral Types in <charconv> Header	July 2022	Complete	16.0
P2302R4	LWG	std::ranges::contains	July 2022			ranges
P2322R6	LWG	ranges::fold	July 2022			ranges
P2374R4	LWG	views::cartesian_product	July 2022			ranges
P2404R3	LWG	Move-only types for equality_comparable_with, totally_ordered_with, and three_way_comparable_with	July 2022
P2408R5	LWG	Ranges iterators as inputs to non-Ranges algorithms	July 2022			ranges
P2417R2	LWG	A more constexpr bitset	July 2022	Complete	16.0
P2419R2	LWG	Clarify handling of encodings in localized formatting of chrono types	July 2022
P2438R2	LWG	std::string::substr() &&	July 2022	Complete	16.0
P2445R1	LWG	forward_like	July 2022	Complete	16.0
P2446R2	LWG	views::as_rvalue	July 2022	Complete	16.0	ranges
P2460R2	LWG	Relax requirements on wchar_t to match existing practices	July 2022
P2465R3	LWG	Standard Library Modules std and std.compat	July 2022
P2467R1	LWG	Support exclusive mode for fstreams	July 2022	Complete	18.0
P2474R2	LWG	views::repeat	July 2022	Complete	17.0	ranges
P2494R2	LWG	Relaxing range adaptors to allow for move only types	July 2022	Complete	17.0	ranges
P2499R0	LWG	string_view range constructor should be explicit	July 2022	Complete	16.0	ranges
P2502R2	LWG	std::generator: Synchronous Coroutine Generator for Ranges	July 2022			ranges
P2508R1	LWG	Exposing std::basic-format-string	July 2022	Complete	15.0
P2513R4	LWG	char8_t Compatibility and Portability Fixes	July 2022
P2517R1	LWG	Add a conditional noexcept specification to std::apply	July 2022	Complete	3.9
P2520R0	LWG	move_iterator should be a random access iterator	July 2022	Complete [3]	17.0	ranges
P2540R1	LWG	Empty Product for certain Views	July 2022			ranges
P2549R1	LWG	std::unexpected should have error() as member accessor	July 2022	Complete	16.0
P2585R0	LWG	Improving default container formatting	July 2022	Complete	17.0
P2590R2	LWG	Explicit lifetime management	July 2022
P2599R2	LWG	mdspan::size_type should be index_type	July 2022	Complete	18.0
P2604R0	LWG	mdspan: rename pointer and contiguous	July 2022	Complete	18.0
P2613R1	LWG	Add the missing empty to mdspan	July 2022	Complete	18.0
P1202R5	LWG	Asymmetric Fences	November 2022			concurrency TS
P1264R2	LWG	Revising the wording of stream input operations	November 2022	Complete	9.0
P1478R8	LWG	Byte-wise atomic memcpy	November 2022			concurrency TS
P2167R3	LWG	Improved Proposed Wording for LWG 2114	November 2022
P2396R1	LWG	Concurrency TS 2 fixes	November 2022			concurrency TS
P2505R5	LWG	Monadic Functions for std::expected	November 2022	Complete	17.0
P2539R4	LWG	Should the output of std::print to a terminal be synchronized with the underlying stream?	November 2022	Complete	18.0	format
P2602R2	LWG	Poison Pills are Too Toxic	November 2022			ranges
P2708R1	LWG	No Further Fundamentals TSes	November 2022	Nothing To Do
P0290R4	LWG	apply() for synchronized_value<T>	February 2023			concurrency TS
P2770R0	LWG	Stashing stashing iterators for proper flattening	February 2023	Partial [5]		ranges
P2164R9	LWG	views::enumerate	February 2023			ranges
P2711R1	LWG	Making multi-param constructors of views explicit	February 2023	In Progress [4]		ranges
P2609R3	LWG	Relaxing Ranges Just A Smidge	February 2023			ranges
P2713R1	LWG	Escaping improvements in std::format	February 2023			format
P2675R1	LWG	format’s width estimation is too approximate and not forward compatible	February 2023	Complete	17.0	format
P2572R1	LWG	std::format fill character allowances	February 2023	Complete	17.0	format
P2693R1	LWG	Formatting thread::id and stacktrace	February 2023	Partial [6]		format
P2679R2	LWG	Fixing std::start_lifetime_as for arrays	February 2023
P2674R1	LWG	A trait for implicit lifetime types	February 2023
P2655R3	LWG	common_reference_t of reference_wrapper Should Be a Reference Type	February 2023
P2652R2	LWG	Disallow User Specialization of allocator_traits	February 2023
P2787R1	LWG	pmr::generator - Promise Types are not Values	February 2023
P2614R2	LWG	Deprecate numeric_limits::has_denorm	February 2023	Complete	18.0
P2588R3	LWG	barrier’s phase completion guarantees	February 2023
P2763R1	LWG	layout_stride static extents default constructor fix	February 2023
P2736R2	CWG	Referencing The Unicode Standard	February 2023			format

Note

[1]

P0533R9: isfinite, isinf, isnan and isnormal are implemented.

[2]

P1413R3: std::aligned_storage_t and std::aligned_union_t are marked deprecated, but clang doesn’t issue a diagnostic for deprecated using template declarations.

[3]

P2520R0: Libc++ implemented this paper as a DR in C++20 as well.

[4]

P2711R1: join_with_view hasn’t been done yet since this type isn’t implemented yet.

[5]

P2770R0: join_with_view hasn’t been done yet since this type isn’t implemented yet.

[6]

P2693R1: The formatter for std::thread::id is implemented. The formatter for stacktrace is not implemented, since stacktrace is not implemented yet.

Library Working Group Issues Status

Issue #	Issue Name	Meeting	Status	First released version	Labels
2839	Self-move-assignment of library types, again	November 2020	Nothing To Do
3117	Missing packaged_task deduction guides	November 2020	Complete	16.0
3143	monotonic_buffer_resource growth policy is unclear	November 2020
3195	What is the stored pointer value of an empty weak_ptr?	November 2020	Nothing To Do
3211	std::tuple<> should be trivially constructible	November 2020	Complete	9.0
3236	Random access iterator requirements lack limiting relational operators domain to comparing those from the same range	November 2020	Nothing To Do
3265	move_iterator’s conversions are more broken after P1207	November 2020	Resolved by LWG3435
3435	three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>>	November 2020	Complete	13.0
3432	Missing requirement for comparison_category	November 2020	Complete	16.0	spaceship
3447	Deduction guides for take_view and drop_view have different constraints	November 2020	Complete	14.0	ranges
3450	The const overloads of take_while_view::begin/end are underconstrained	November 2020	Complete	16.0	ranges
3464	istream::gcount() can overflow	November 2020	Complete	18.0
2731	Existence of lock_guard<MutexTypes...>::mutex_type typedef unclear	November 2020	Complete	5.0
2743	P0083R3 node_handle private members missing “exposition only” comment	November 2020	Nothing To Do
2820	Clarify <cstdint> macros	November 2020	Nothing To Do
3120	Unclear behavior of monotonic_buffer_resource::release()	November 2020
3170	is_always_equal added to std::allocator makes the standard library treat derived types as always equal	November 2020	Complete	18.0
3036	polymorphic_allocator::destroy is extraneous	November 2020
3171	LWG2989 breaks directory_entry stream insertion	November 2020	Complete	14.0
3306	ranges::advance violates its preconditions	November 2020	Complete	14.0	ranges
3403	Domain of ranges::ssize(E) doesn’t match ranges::size(E)	November 2020			ranges
3404	Finish removing subrange’s conversions from pair-like	November 2020			ranges
3405	common_view’s converting constructor is bad, too	November 2020	Complete	14.0	ranges
3406	elements_view::begin() and elements_view::end() have incompatible constraints	November 2020	Complete	16.0	ranges
3419	[algorithms.requirements]/15 doesn’t reserve as many rights as it intends to	November 2020	Nothing To Do
3420	cpp17-iterator should check that the type looks like an iterator first	November 2020	Complete	14.0	ranges
3421	Imperfect ADL emulation for boolean-testable	November 2020	Nothing To Do		ranges
3425	condition_variable_any fails to constrain its Lock parameters	November 2020	Nothing To Do
3426	operator<=>(const unique_ptr<T, D>&, nullptr_t) can’t get no satisfaction	November 2020	Complete	16.0	spaceship
3427	operator<=>(const shared_ptr<T>&, nullptr_t) definition ill-formed	November 2020	Complete	16.0	spaceship
3428	single_view’s in place constructor should be explicit	November 2020	Complete	14.0	ranges
3434	ios_base never reclaims memory for iarray and parray	November 2020	Nothing To Do
3437	__cpp_lib_polymorphic_allocator is in the wrong header	November 2020	Complete	14.0
3446	indirectly_readable_traits ambiguity for types with both value_type and element_type	November 2020	Complete	14.0	ranges
3448	transform_view’s sentinel<false> not comparable with iterator<true>	November 2020			ranges
3449	take_view and take_while_view’s sentinel<false> not comparable with their const iterator	November 2020	Complete	16.0	ranges
3453	Generic code cannot call ranges::advance(i, s)	November 2020	Nothing To Do		ranges
3455	Incorrect Postconditions on unique_ptr move assignment	November 2020	Nothing To Do
3460	Unimplementable noop_coroutine_handle guarantees	November 2020	Complete	14.0
3461	convertible_to’s description mishandles cv-qualified void	November 2020	Nothing To Do
3465	compare_partial_order_fallback requires F < E	November 2020	Complete	14.0	spaceship
3466	Specify the requirements for promise/future/shared_future consistently	November 2020	Nothing To Do
3467	bool can’t be an integer-like type	November 2020	Complete	14.0	ranges
3472	counted_iterator is missing preconditions	November 2020	Complete	14.0	ranges
3473	Normative encouragement in non-normative note	November 2020	Complete	15.0	format
3474	Nesting join_views is broken because of CTAD	November 2020	Complete	15.0	ranges
3476	thread and jthread constructors require that the parameters be move-constructible but never move construct the parameters	November 2020
3477	Simplify constraints for semiregular-box	November 2020			ranges
3482	drop_view’s const begin should additionally require sized_range	November 2020	Complete	14.0	ranges
3483	transform_view::iterator’s difference is overconstrained	November 2020	Complete	14.0	ranges
3391	Problems with counted_iterator/move_iterator::base() const &	February 2021			ranges
3433	subrange::advance(n) has UB when n < 0	February 2021	Complete	14.0	ranges
3490	ranges::drop_while_view::begin() is missing a precondition	February 2021	Nothing To Do		ranges
3492	Minimal improvements to elements_view::iterator	February 2021	Complete	16.0	ranges
3494	Allow ranges to be conditionally borrowed	February 2021	Superseded by P2017R1		ranges
3495	constexpr launder makes pointers to inactive members of unions usable	February 2021	Nothing To Do
3500	join_view::iterator::operator->() is bogus	February 2021	Complete	14.0	ranges
3502	elements_view should not be allowed to return dangling reference	February 2021	Complete	16.0	ranges
3505	split_view::outer-iterator::operator++ misspecified	February 2021			ranges
2774	std::function construction vs assignment	June 2021
2818	::std:: everywhere rule needs tweaking	June 2021	Nothing To Do
2997	LWG 491 and the specification of {forward_,}list::unique	June 2021
3410	lexicographical_compare_three_way is overspecified	June 2021	Complete	17.0	spaceship
3430	std::fstream & co. should be constructible from string_view	June 2021
3462	§[formatter.requirements]: Formatter requirements forbid use of fc.arg()	June 2021			format
3481	viewable_range mishandles lvalue move-only views	June 2021	Superseded by P2415R2		ranges
3506	Missing allocator-extended constructors for priority_queue	June 2021	Complete	14.0
3517	join_view::iterator’s iter_swap is underconstrained	June 2021	Complete	14.0	ranges
3518	Exception requirements on char trait operations unclear	June 2021	Nothing To Do
3519	Incomplete synopses for <random> classes	June 2021
3520	iter_move and iter_swap are inconsistent for transform_view::iterator	June 2021	Complete	14.0	ranges
3521	Overly strict requirements on qsort and bsearch	June 2021	Nothing To Do
3522	Missing requirement on InputIterator template parameter for priority_queue constructors	June 2021	Complete	14.0
3523	iota_view::sentinel is not always iota_view’s sentinel	June 2021			ranges
3526	Return types of uses_allocator_construction_args unspecified	June 2021
3527	uses_allocator_construction_args handles rvalue pairs of rvalue references incorrectly	June 2021
3528	make_from_tuple can perform (the equivalent of) a C-style cast	June 2021
3529	priority_queue(first, last) should construct c with (first, last)	June 2021	Complete	14.0
3530	BUILTIN-PTR-MEOW should not opt the type out of syntactic checks	June 2021
3532	split_view<V, P>::inner-iterator<true>::operator++(int) should depend on Base	June 2021			ranges
3533	Make base() const & consistent across iterator wrappers that supports input_iterators	June 2021	Complete	14.0	ranges
3536	Should chrono::from_stream() assign zero to duration for failure?	June 2021			chrono
3539	format_to must not copy models of output_iterator<const charT&>	June 2021	Complete	14.0	format
3540	§[format.arg] There should be no const in basic_format_arg(const T* p)	June 2021	Complete	14.0	format
3541	indirectly_readable_traits should be SFINAE-friendly for all types	June 2021	Complete	14.0	ranges
3542	basic_format_arg mishandles basic_string_view with custom traits	June 2021	Complete	14.0	format
3543	Definition of when counted_iterators refer to the same sequence isn’t quite right	June 2021	Nothing To Do		ranges
3544	format-arg-store::args is unintentionally not exposition-only	June 2021	Complete	14.0	format
3546	common_iterator’s postfix-proxy is not quite right	June 2021			ranges
3548	shared_ptr construction from unique_ptr should move (not copy) the deleter	June 2021	Complete	15.0
3549	view_interface is overspecified to derive from view_base	June 2021	Complete	14.0	ranges
3551	borrowed_{iterator,subrange}_t are overspecified	June 2021	Nothing To Do		ranges
3552	Parallel specialized memory algorithms should require forward iterators	June 2021
3553	Useless constraint in split_view::outer-iterator::value_type::begin()	June 2021			ranges
3555	{transform,elements}_view::iterator::iterator_concept should consider const-qualification of the underlying range	June 2021			ranges
2191	Incorrect specification of match_results(match_results&&)	October 2021	Nothing To Do
2381	Inconsistency in parsing floating point numbers	October 2021
2762	unique_ptr operator*() should be noexcept	October 2021
3121	tuple constructor constraints for UTypes&&... overloads	October 2021
3123	duration constructor from representation shouldn’t be effectively non-throwing	October 2021			chrono
3146	Excessive unwrapping in std::ref/cref	October 2021	Complete	14.0
3152	common_type and common_reference have flaws in common	October 2021
3293	move_iterator operator+() has incorrect constraints	October 2021	Complete	15.0
3361	safe_range<SomeRange&> case	October 2021	Nothing To Do		ranges
3392	ranges::distance() cannot be used on a move-only iterator with a sized sentinel	October 2021	Complete	14.0	ranges
3407	Some problems with the wording changes of P1739R4	October 2021	Complete	15.0	ranges
3422	Issues of seed_seq’s constructors	October 2021	Complete	14.0
3470	convertible-to-non-slicing seems to reject valid case	October 2021	Complete	14.0	ranges
3480	directory_iterator and recursive_directory_iterator are not C++20 ranges	October 2021	Complete	14.0	ranges
3498	Inconsistent noexcept-specifiers for basic_syncbuf	October 2021
3535	join_view::iterator::iterator_category and ::iterator_concept lie	October 2021	Complete	15.0	ranges
3554	chrono::parse needs const charT* and basic_string_view<charT> overloads	October 2021			chrono
3557	The static_cast expression in convertible_to has the wrong operand	October 2021	Complete	14.0
3559	Semantic requirements of sized_range is circular	October 2021	Nothing To Do		ranges
3560	ranges::equal and ranges::is_permutation should short-circuit for sized_ranges	October 2021			ranges
3561	Issue with internal counter in discard_block_engine	October 2021
3563	keys_view example is broken	October 2021			ranges
3566	Constraint recursion for operator<=>(optional<T>, U)	October 2021	Complete	17.0	spaceship
3567	Formatting move-only iterators take two	October 2021	Complete	16.0	format ranges
3568	basic_istream_view needs to initialize value_	October 2021	Complete	16.0	ranges
3570	basic_osyncstream::emit should be an unformatted output function	October 2021	Complete	18.0
3571	flush_emit should set badbit if the emit call fails	October 2021
3572	copyable-box should be fully constexpr	October 2021	Complete	14.0	ranges
3573	Missing Throws element for basic_string_view(It begin, End end)	October 2021	Complete	14.0
3574	common_iterator should be completely constexpr-able	October 2021	Complete	14.0	ranges
3580	iota_view’s iterator’s binary operator+ should be improved	October 2021	Complete	14.0	ranges
3581	The range constructor makes basic_string_view not trivially move constructible	October 2021	Complete	14.0	ranges
3585	variant converting assignment with immovable alternative	October 2021
3589	The const lvalue reference overload of get for subrange does not constrain I to be copyable when N == 0	October 2021	Complete	14.0	ranges
3590	split_view::base() const & is overconstrained	October 2021	Complete	16.0	ranges
3591	lazy_split_view<input_view>::inner-iterator::base() && invalidates outer iterators	October 2021			ranges
3592	lazy_split_view needs to check the simpleness of Pattern	October 2021			ranges
3593	Several iterators’ base() const & and lazy_split_view::outer-iterator::value_type::end() missing noexcept	October 2021			ranges
3595	Exposition-only classes proxy and postfix-proxy for common_iterator should be fully constexpr	October 2021	Complete	14.0	ranges
3088	forward_list::merge behaviour unclear when passed *this	February 2022
3471	polymorphic_allocator::allocate does not satisfy Cpp17Allocator requirements	February 2022
3525	uses_allocator_construction_args fails to handle types convertible to pair	February 2022
3598	system_category().default_error_condition(0) is underspecified	February 2022
3601	common_iterator’s postfix-proxy needs indirectly_readable	February 2022			ranges
3607	contiguous_iterator should not be allowed to have custom iter_move and iter_swap behavior	February 2022	Nothing To Do		ranges
3610	iota_view::size sometimes rejects integer-class types	February 2022			ranges
3612	Inconsistent pointer alignment in std::format	February 2022	Complete	14.0	format
3616	LWG 3498 seems to miss the non-member swap for basic_syncbuf	February 2022
3618	Unnecessary iter_move for transform_view::iterator	February 2022			ranges
3619	Specification of vformat_to contains ill-formed formatted_size calls	February 2022	Nothing To Do		format
3621	Remove feature-test macro __cpp_lib_monadic_optional	February 2022	Complete	15.0
3632	unique_ptr “Mandates: This constructor is not selected by class template argument deduction”	February 2022	Nothing To Do
3643	Missing constexpr in std::counted_iterator	February 2022			ranges
3648	format should not print bool with 'c'	February 2022	Complete	15.0	format
3649	[fund.ts.v2] Reinstate and bump __cpp_lib_experimental_memory_resource feature test macro	February 2022
3650	Are std::basic_string ‘s iterator and const_iterator constexpr iterators?	February 2022	Nothing To Do
3654	basic_format_context::arg(size_t) should be noexcept	February 2022	Complete	15.0	format
3657	std::hash<std::filesystem::path> is not enabled	February 2022	Complete	17.0
3660	iterator_traits<common_iterator>::pointer should conform to §[iterator.traits]	February 2022	Complete	14.0	ranges
3661	constinit atomic<shared_ptr<T>> a(nullptr); should work	February 2022
3564	transform_view::iterator<true>::value_type and iterator_category should use const F&	July 2022			ranges
3617	function/packaged_task deduction guides and deducing this	July 2022
3656	Inconsistent bit operations returning a count	July 2022	Complete	15.0
3659	Consider ATOMIC_FLAG_INIT undeprecation	July 2022	Complete	15.0
3670	Cpp17InputIterators don’t have integer-class difference types	July 2022			ranges
3671	atomic_fetch_xor missing from stdatomic.h	July 2022
3672	common_iterator::operator->() should return by value	July 2022			ranges
3683	operator== for polymorphic_allocator cannot deduce template argument in common cases	July 2022
3687	expected<cv void, E> move constructor should move	July 2022	Complete	16.0
3692	zip_view::iterator’s operator<=> is overconstrained	July 2022			ranges spaceship
3701	Make formatter<remove_cvref_t<const charT[N]>, charT> requirement explicit	July 2022			format
3702	Should zip_transform_view::iterator remove operator<	July 2022			ranges spaceship
3703	Missing requirements for expected<T, E> requires is_void<T>	July 2022	Complete	16.0
3704	LWG 2059 added overloads that might be ill-formed for sets	July 2022
3705	Hashability shouldn’t depend on basic_string’s allocator	July 2022	Complete	16.0
3707	chunk_view::outer-iterator::value_type::size should return unsigned type	July 2022			ranges
3708	take_while_view::sentinel’s conversion constructor should move	July 2022	Complete	16.0	ranges
3709	LWG-3703 was underly ambitious	July 2022
3710	The end of chunk_view for input ranges can be const	July 2022			ranges
3711	Missing preconditions for slide_view constructor	July 2022			ranges
3712	chunk_view and slide_view should not be default_initializable	July 2022			ranges
3713	Sorted with respect to comparator (only)	July 2022
3715	view_interface::empty is overconstrained	July 2022			ranges
3719	Directory iterators should be usable with default sentinel	July 2022	Complete	17.0	ranges
3721	Allow an arg-id with a value of zero for width in std-format-spec	July 2022	Complete	16.0	format
3724	decay-copy should be constrained	July 2022	Complete	14.0
3028	Container requirements tables should distinguish const and non-const variables	November 2022
3118	fpos equality comparison unspecified	November 2022
3177	Limit permission to specialize variable templates to program-defined types	November 2022	Nothing To Do
3515	§[stacktrace.basic.nonmem]: operator<< should be less templatized	November 2022
3545	std::pointer_traits should be SFINAE-friendly	November 2022	Complete	18.0
3569	join_view fails to support ranges of ranges with non-default_initializable iterators	November 2022			ranges
3594	inout_ptr — inconsistent release() in destructor	November 2022
3597	Unsigned integer types don’t model advanceable	November 2022			ranges
3600	Making istream_iterator copy constructor trivial is an ABI break	November 2022
3629	make_error_code and make_error_condition are customization points	November 2022	Complete	16.0
3636	formatter<T>::format should be const-qualified	November 2022	Complete	16.0	format
3646	std::ranges::view_interface::size returns a signed type	November 2022	Complete	16.0	ranges
3677	Is a cv-qualified pair specially handled in uses-allocator construction?	November 2022	Complete	18.0
3717	common_view::end should improve random_access_range case	November 2022			ranges
3732	prepend_range and append_range can’t be amortized constant time	November 2022	Nothing To Do		ranges
3736	move_iterator missing disable_sized_sentinel_for specialization	November 2022			ranges
3737	take_view::sentinel should provide operator-	November 2022			ranges
3738	Missing preconditions for take_view constructor	November 2022	Complete	16.0	ranges
3743	ranges::to’s reserve may be ill-formed	November 2022			ranges
3745	std::atomic_wait and its friends lack noexcept	November 2022	Complete	16.0
3746	optional’s spaceship with U with a type derived from optional causes infinite constraint meta-recursion	November 2022	Complete	17.0	spaceship
3747	ranges::uninitialized_copy_n, ranges::uninitialized_move_n, and ranges::destroy_n should use std::move	November 2022			ranges
3750	Too many papers bump __cpp_lib_format	November 2022	Partial [7]		format
3751	Missing feature macro for flat_set	November 2022			flat containers
3753	Clarify entity vs. freestanding entity	November 2022
3754	Class template expected synopsis contains declarations that do not match the detailed description	November 2022	Nothing To Do
3755	tuple-for-each can call user-defined operator,	November 2022	Complete	17.0
3757	What’s the effect of std::forward_like<void>(x)?	November 2022
3759	ranges::rotate_copy should use std::move	November 2022	Complete	15.0	ranges
3760	cartesian_product_view::iterator’s parent_ is never valid	November 2022			ranges
3761	cartesian_product_view::iterator::operator- should pass by reference	November 2022			ranges
3762	generator::iterator::operator== should pass by reference	November 2022
3764	reference_wrapper::operator() should propagate noexcept	November 2022	Complete	17.0
3765	const_sentinel should be constrained	November 2022			ranges
3766	view_interface::cbegin is underconstrained	November 2022			ranges
3770	const_sentinel_t is missing	November 2022			ranges
3773	views::zip_transform still requires F to be copy_constructible when empty pack	November 2022			ranges
3774	<flat_set> should include <compare>	November 2022			flat containers
3775	Broken dependencies in the Cpp17Allocator requirements	November 2022
3778	vector<bool> missing exception specifications	November 2022
3781	The exposition-only alias templates cont-key-type and cont-mapped-type should be removed	November 2022	Nothing To Do
3782	Should <math.h> declare ::lerp?	November 2022	Complete	17.0
3784	std.compat should not provide ::byte and its friends	November 2022
3785	ranges::to is over-constrained on the destination type being a range	November 2022			ranges
3788	jthread::operator=(jthread&&) postconditions are unimplementable under self-assignment	November 2022
3792	__cpp_lib_constexpr_algorithms should also be defined in <utility>	November 2022	Complete	16.0
3795	Self-move-assignment of std::future and std::shared_future have unimplementable postconditions	November 2022
3796	movable-box as member should use default-initialization instead of copy-initialization	November 2022			ranges
3798	Rvalue reference and iterator_category	November 2022	Partial [8]		ranges
3801	cartesian_product_view::iterator::distance-from ignores the size of last underlying range	November 2022			ranges
3814	Add freestanding items requested by NB comments	November 2022
3816	flat_map and flat_multimap should impose sequence container requirements	November 2022			flat containers
3817	Missing preconditions on forward_list modifiers	November 2022
3818	Exposition-only concepts are not described in library intro	November 2022	Nothing To Do
3822	Avoiding normalization in filesystem::weakly_canonical	November 2022
3823	Unnecessary precondition for is_aggregate	November 2022
3824	Number of bind placeholders is underspecified	November 2022	Nothing To Do
3826	Redundant specification [for overload of yield_value]	November 2022
2195	Missing constructors for match_results	February 2023
2295	Locale name when the provided Facet is a nullptr	February 2023
3032	ValueSwappable requirement missing for push_heap and make_heap	February 2023
3085	char_traits::copy precondition too weak	February 2023
3664	LWG 3392 broke std::ranges::distance(a, a+3)	February 2023			ranges
3720	Restrict the valid types of arg-id for width and precision in std-format-spec	February 2023	Complete	17.0	format
3756	Is the std::atomic_flag class signal-safe?	February 2023
3769	basic_const_iterator::operator== causes infinite constraint recursion	February 2023			spaceship
3807	The feature test macro for ranges::find_last should be renamed	February 2023			ranges
3811	views::as_const on ref_view<T> should return ref_view<const T>	February 2023			ranges
3820	cartesian_product_view::iterator::prev is not quite right	February 2023			ranges
3825	Missing compile-time argument id check in basic_format_parse_context::next_arg_id	February 2023	Complete	17.0	format
3204	sub_match::swap only swaps the base class	February 2023	Complete	17.0
3733	ranges::to misuses cpp17-input-iterator	February 2023	Complete	17.0	ranges
3742	deque::prepend_range needs to permute	February 2023			ranges
3790	P1467 accidentally changed nexttoward’s signature	February 2023
3819	reference_meows_from_temporary should not use is_meowible	February 2023
3821	uses_allocator_construction_args should have overload for pair-like	February 2023	Complete	18.0
3834	Missing constexpr for std::intmax_t math functions in <cinttypes>	February 2023
3839	range_formatter’s set_separator, set_brackets, and underlying functions should be noexcept	February 2023	Complete	17.0	format
3841	<version> should not be “all freestanding”	February 2023
3842	Unclear wording for precision in chrono-format-spec	February 2023	Complete	16.0	format
3848	adjacent_view, adjacent_transform_view and slide_view missing base accessor	February 2023			ranges
3849	cartesian_product_view::iterator’s default constructor is overconstrained	February 2023			ranges
3850	views::as_const on empty_view<T> should return empty_view<const T>	February 2023			ranges
3851	chunk_view::inner-iterator missing custom iter_move and iter_swap	February 2023			ranges
3853	basic_const_iterator<volatile int*>::operator-> is ill-formed	February 2023
3857	basic_string_view should allow explicit conversion when only traits vary	February 2023	Complete	17.0
3860	range_common_reference_t is missing	February 2023	Complete	17.0	ranges
3866	Bad Mandates for expected::transform_error overloads	February 2023	Complete	17.0
3867	Should std::basic_osyncstream’s move assignment operator be noexcept?	February 2023	Complete	18.0
3441	Misleading note about calls to customization points	February 2023
3622	Misspecified transitivity of equivalence in §[unord.req.general]	February 2023
3631	basic_format_arg(T&&) should use remove_cvref_t<T> throughout	February 2023	Complete	17.0
3645	resize_and_overwrite is overspecified to call its callback with lvalues	February 2023	Complete	14.0
3655	The INVOKE operation and union types	February 2023	Complete	18.0
3723	priority_queue::push_range needs to append_range	February 2023			ranges
3734	Inconsistency in inout_ptr and out_ptr for empty case	February 2023
3772	repeat_view’s piecewise constructor is missing Postconditions	February 2023			ranges
3786	Flat maps’ deduction guide needs to default Allocator to be useful	February 2023
3803	flat_foo constructors taking KeyContainer lack KeyCompare parameter	February 2023
3810	CTAD for std::basic_format_args	February 2023	Complete	17.0	format
3827	Deprecate <stdalign.h> and <stdbool.h> macros	February 2023
3828	Sync intmax_t and uintmax_t with C2x	February 2023
3833	Remove specialization template<size_t N> struct formatter<const charT[N], charT>	February 2023	Complete	17.0	format
3836	std::expected<bool, E1> conversion constructor expected(const expected<U, G>&) should take precedence over expected(U&&) with operator bool	February 2023	Complete	18.0
3843	std::expected<T,E>::value() & assumes E is copy constructible	February 2023	Complete	17.0
3847	ranges::to can still return views	February 2023	Complete	17.0	ranges
3862	basic_const_iterator’s common_type specialization is underconstrained	February 2023
3865	Sorting a range of pairs	February 2023	Complete	17.0	ranges
3869	Deprecate std::errc constants related to UNIX STREAMS	February 2023
3870	Remove voidify	February 2023
3871	Adjust note about terminate	February 2023
3872	basic_const_iterator should have custom iter_move	February 2023
3875	std::ranges::repeat_view<T, IntegerClass>::iterator may be ill-formed	February 2023	Complete	17.0	ranges
3876	Default constructor of std::layout_XX::mapping misses precondition	February 2023
3877	Incorrect constraints on const-qualified monadic overloads for std::expected	February 2023	Complete	17.0
3878	import std; should guarantee initialization of standard iostreams objects	February 2023
3879	erase_if for flat_{,multi}set is incorrectly specified	February 2023
3880	Clarify operator+= complexity for {chunk,stride}_view::iterator	February 2023			ranges
3881	Incorrect formatting of container adapters backed by std::string	February 2023	Complete	17.0	format

Note

[7]

LWG3750 Only __cpp_lib_format_ranges is fully implemented.

[8]

LWG3798: join_with_view, zip_transform_view, and adjacent_transform_view haven’t been done yet since these types aren’t implemented yet.