libc++ C++29 Status

Overview

In June 2026, the C++ standard committee adopted the first changes to the next version of the C++ standard, known here as “C++29”.

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 #	Paper Name	Meeting	Status	First released version	GitHub issue	Notes
P2434R5	Nondeterministic pointer provenance	2026-06 (Brno)				Voted as a Defect Report.
P4101R1	Consteval-only Values for C++26	2026-06 (Brno)				Voted as a Defect Report.
P2414R12	Pointer lifetime-end zap proposed solutions	2026-06 (Brno)				Voted as a Defect Report.
P3319R6	Add an iota object for simd (and more)	2026-06 (Brno)
P3798R1	The unexpected in std::expected	2026-06 (Brno)
P3052R2	view_interface::at()	2026-06 (Brno)
P4206R0	Revert string support in std::constant_wrapper	2026-06 (Brno)				To be applied as a Defect Report.
P3395R6	Fix encoding issues and add a formatter for std::error_code	2026-06 (Brno)
P3505R4	Fix the default floating-point representation in std::format	2026-06 (Brno)				To be applied as a Defect Report.
P3154R3	Deprecating signed character types in iostreams	2026-06 (Brno)
P3428R4	Hazard Pointer Batches	2026-06 (Brno)
P3248R5	Require [u]intptr_t	2026-06 (Brno)
P3793R2	Better shifting	2026-06 (Brno)
P3242R4	Copy and fill for mdspan	2026-06 (Brno)
P3692R4	How to Avoid OOTA Without Really Trying	2026-06 (Brno)
P3104R6	Bit permutations	2026-06 (Brno)
P3772R2	std::simd overloads for bit permutations	2026-06 (Brno)
P3091R6	Better Lookups for map, unordered_map, and flat_map	2026-06 (Brno)
P3125R6	constexpr pointer tagging	2026-06 (Brno)
P2019R9	Thread attributes	2026-06 (Brno)
P3785R1	Library Wording Changes for Defaulted Postfix Increment and Decrement Operations	2026-06 (Brno)

Library Working Group Issues Status

Issue #	Issue Name	Meeting	Status	First released version	GitHub issue	Notes
LWG3417	Missing volatile atomic deprecations	2026-06 (Brno)
LWG4121	ranges::to constructs associative containers via c.emplace(c.end(), *it)	2026-06 (Brno)
LWG4125	move_iterator’s default constructor should be constrained	2026-06 (Brno)
LWG4158	packaged_task::operator= should abandon its shared state	2026-06 (Brno)
LWG4182	Definition of NULL is too broad	2026-06 (Brno)
LWG4218	Constraint recursion in basic_const_iterator’s relational operators due to ADL + CWG 2369	2026-06 (Brno)
LWG4249	The past end issue for lazy_split_view	2026-06 (Brno)
LWG4267	Uses-allocator construction is meaningless for tuple of references	2026-06 (Brno)
LWG4359	as_awaitable(expr, p) does not define semantics of call if p is not an lvalue	2026-06 (Brno)
LWG4385	Including <simd> doesn’t provide std::begin/end	2026-06 (Brno)
LWG4471	Remove test for get_env noexcept-ness from inline_scheduler	2026-06 (Brno)
LWG4487	Is member is_steady of a Cpp17Clock type required to be usable in constant expressions?	2026-06 (Brno)
LWG4490	Allow calling std::ranges::size in ranges algorithms	2026-06 (Brno)
LWG4521	Improve [atomics.order] p10 to have a consistent way with [intro.races]	2026-06 (Brno)
LWG4531	Should there be a feature-test macro update for constexpr std::to_(w)string?	2026-06 (Brno)
LWG4567	Feature test macro value for apply_result, is_applicable	2026-06 (Brno)
LWG4568	std::execution::spawn_future is mishandling dependent senders	2026-06 (Brno)
LWG4579	make-state<Rcvr>::state-type::complete uses Env which is not in scope	2026-06 (Brno)