// WG21 · Updates

Paper Status Updates

Reporting all papers with revisions for selected dates and target groups. Papers may not be included as plenary discussion is not guaranteed.

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Showing 140 of 140 papers

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P3220R3 SG9LEWGLWGDG

views::take_before

Hewill Kang

P1974R1 EWG

Persistent constexpr allocation

Jeff Snyder

P2034R8 EWGCWG

Partially Mutable Lambda Captures

Ryan McDougall, Lakshay Garg

P2287R6 EWG Approved

Designated-initializers for base classes

Barry Revzin

P2806R4 EWG

do expressions

Barry Revzin, Bruno Cardoso Lopez, Zach Laine, Michael Park

P2826R4 EWG

Expression Aliases

Gašper Ažman

P3400R4 EWG

Controlling Contract-Assertion Properties

Joshua Berne

P3812R1 EWGCWG

const and & in default member functions

Jarrad J Waterloo

P3822R2 EWG Approved

Conditional noexcept specifiers in compound requirements

Viacheslav Luchkin, Gašper Ažman

P4033R1 SG7EWG

Synthesizing enum at compile time with define_enum

Aurelien Cassagnes

P4101R1 EWGCWG Approved

Consteval-only Values for C++26

Barry Revzin, Peter Dimov, Daveed Vandevoorde, Dan Katz

P4222R1 SG23EWG

An initialization profile (R2)

Bjarne Stroustrup

P4234R2 SG22EWG

$identifiers

Matthias Wippich, Murat Can Çağrı

P4262R0 EWG New

Design Considerations for Class Invariants

Joshua Berne

P4281R0 EWGCWG New

Type Aliases in Requires-Expressions

Hewill Kang

P4283R0 EWG New

Requires clauses for Contract Assertions

Joshua Berne

P4297R0 EWG New

Severing P3100's Profiles Claim from Its Case-by-Case Review

Vinnie Falco, Ville Voutilainen

P4298R0 EWG New

Nonthrowing Evaluation Semantics

Joshua Berne

P4304R0 EWGIEWG New

Zero-Copy `co_return`

Yuxuan Chen

P4308R0 EWG New

Eight Responses to a Throwing Implicit Contract Assertion

Vinnie Falco, Ville Voutilainen

P4317R0 SG22EWG New

A Profile for Runtime-Checkable Core-Language Undefined Behavior: std::core_ub

Vinnie Falco

P0260R20 SG1LEWG

C++ Concurrent Queues

Detlef Vollmann, Lawrence Crowl, Chris Mysen, Gor Nishanov

P0870R8 SG6LEWGLWG

A proposal for a type trait to detect narrowing conversions

Giuseppe D'Angelo

P1040R11 LEWGCWG

std::embed and #depend

JeanHeyd Meneide

P2721R1 LEWG

Deprecating function in C++29

Michael Florian Hava

P2728R14 SG9SG16LEWG

Unicode in the Library, Part 1: UTF Transcoding

Eddie Nolan

P2906R2 LEWG

Structured bindings for std::extents

Bernhard Manfred Gruber, Yihan Wang, Mark Hoemmen

P2964R5 SG6LEWG

Allowing user-defined types in std::simd

Daniel Towner, Ruslan Arutyunyan

P3045R9 SG16LEWG

Quantities and units library

Mateusz Pusz, Dominik Berner, Johel Ernesto Guerrero Peña, Charles Hogg, Nicolas Holthaus, Roth Michaels, Vincent Reverdy

P3099R3 EWGLEWG

Contracts for C++: User-defined diagnostic messages

Timur Doumler, Peter Bindels, Joshua Berne

P3100R7 EWGLEWG

A framework for systematically addressing undefined behaviour in the C++ Standard

Timur Doumler, Joshua Berne

P3125R6 LEWGLWG Approved

constexpr pointer tagging

Hana Dusíková

P3155R1 LEWG

noexcept policy for SD-9 (The Lakos Rule)

Timur Doumler, John Lakos

P3211R2 SG9LEWGLWG

views::flat_map

Hewill Kang

P3216R3 SG9LEWGLWG

views::slice

Hewill Kang

P3230R3 SG9LEWGLWG

views::unchecked_(take|drop)

Hewill Kang

P3290R6 LEWG

Integrating Existing Assertions With Contracts

Joshua Berne, Timur Doumler, John Lakos

P3385R8 EWGLEWG

Attributes reflection

Aurelien Cassagnes

P3642R6 LEWGLWG

Carry-less product: std::clmul

Jan Schultke

P3655R5 LEWGLWG

cstring_view

Peter Bindels, Hana Dusikova, Jeremy Rifkin, Marco Foco, Alexey Shevlyakov

P3669R4 LEWGLWG

Non-Blocking Support for `std::execution`

Detlef Vollmann

P3771R1 SG1LEWG

constexpr mutex, locks, and condition variable

Hana Dusíková

P3790R2 LEWGLWG

Pointer lifetime-end zap proposed solutions: Bag-of-bits pointer class

Paul E. McKenney, Maged Michael, Jens Maurer, Peter Sewell, Hans Boehm, Hubert Tong, Niall Douglas, Thomas Rodgers, Will Deacon, Michael Wong, David Goldblatt, Kostya Serebryany, Anthony Williams, Tom Scogland, JF Bastien, Daniel Krügler, David Tenty

P3806R1 SG9LEWGLWG

views::cycle

Hewill Kang

P3832R3 SG1LEWG

Timed lock algorithms for multiple lockables

Ted Lyngmo

P3833R3 SG1LEWG

std::unique_multilock

Ted Lyngmo

P3850R1 EWGLEWG

A proposed plan for extending Contracts in C++29

Timur Doumler, Joshua Berne

P3928R1 SG9LEWGLWG

static_sized_range

Hewill Kang

P3935R2 LEWG

Rebasing <cmath> on C23

Jan Schultke

P3969R2 LEWG

Fixing std::bit_cast of types with padding bits

Jan Schultke

P4030R1 SG9SG16LEWG

Endian Views

Eddie Nolan

P4148R2 LEWGI

protocol: Structural Subtyping for C++

Jonathan B. Coe, Hana Dusikova, Antony Peacock, Philip Craig, Neelofer Banglawala

P4157R1 EWGLEWG

LEWG Slides for P3666R4

Jan Schultke

P4188R1 SG6LEWGISG20LEWGLWG

Extensible Math Functions for C++

Stephane Gros-Lemesre

P4217R1 LEWG

when_all() is just just()

Robert Leahy

P4220R1 LEWG

Design goals for zstring_view

Andrzej Krzemieński

P4221R3 LEWG

Atomic Compare

Maged Michael, Paul McKenney, Michael Wong

P4226R0 LEWG New

2026-05 Library Evolution Poll Outcomes

Inbal Levi, Fabio Fracassi, Andreas Weis, Corentin Jabot

P4243R0 SG9LEWG New

`zip()` Should Be Ill-formed

Hui Xie, Tristan Melen

P4254R0 LEWG New

Throwing Violation Handlers Are Post Hoc Library Design

Robert Leahy

P4257R0 LEWG New

Marking wide contract non-throwing functions noexcept is not controversial

Nevin Liber

P4259R0 LEWG New

The name of the floor division function should probably have floor in it

Barry Revzin

P4269R0 SG1LEWG New

when_all Oughtn't Hallucinate set_stopped

Robert Leahy

P4276R0 LEWG New

A Policy for Scalar Overloads in std::simd

Daniel Towner

P4279R0 LEWG New

No Endian Views

Jan Schultke

P4282R0 SG1LEWG New

Away From co_yield For std::execution::task

Robert Leahy

P4288R0 SG1LEWG New

Stop the Decay

Robert Leahy

P4291R0 SG9LEWGLWG New

views::unique

Hewill Kang

P4293R0 SG1LEWG New

std::execution::decay_copy

Robert Leahy

P4294R0 SG9LEWGLWG New

views::take_last and views::drop_last

Hewill Kang

P4295R0 SG1LEWG New

Single Ends for C++ Concurrent Queues

Detlef Vollmann

P4305R0 LEWG New

Design problems with P2964R5 (User-defined element types in std::simd)

Jan Schultke

P4309R0 LEWG New

Constructing owning node-handles without containers

Michael Florian Hava

P4311R0 LEWG New

Getting a const element type version of an mdspan accessor, and of an mdspan too

Mark Hoemmen, Rob Parolin

P4313R0 LEWG New

Bitmask operations for enums

Iliya Guterman, Anthony Williams

P4320R0 SG1LEWG New

std::execution::sequence

Robert Leahy

P0876R24 CWGLWG

fiber_context - fibers without scheduler

Oliver Kowalke, Nat Goodspeed

P2434R5 SG22CWGLWG Approved

Nondeterministic pointer provenance

S. Davis Herring

P2719R7 CWG

Type-aware allocation and deallocation functions

Louis Dionne, Oliver Hunt, Vlad Serebrennikov

P2828R3 CWG

Copy elision for direct-initialization with a conversion function (Core issue 2327)

Brian Bi, Nhat Nguyen

P2953R5 CWG Approved

Adding restrictions to defaulted assignment operator functions

Matthew Taylor, Arthur O'Dwyer

P3097R3 CWG Approved

Contracts for C++: Virtual functions

Timur Doumler, Joshua Berne, Gašper Ažman

P3347R6 CWG Approved

Invalid/Prospective Pointer Operations

Paul E. McKenney, Maged Michael, Jens Maurer, Peter Sewell, Martin Uecker, Hans Boehm, Hubert Tong, Niall Douglas, Thomas Rodgers, Will Deacon, Michael Wong, David Goldblatt, Kostya Serebryany, Anthony Williams, Tom Scogland, JF Bastien, Jason McGuiness, David Tenty

P3367R5 CWGLWG

constexpr coroutines

Hana Dusíková

P3596R3 CWG Approved

Undefined Behavior and IFNDR Annexes

Joshua Berne, Timur Doumler, Jens Maurer, Shafik Yaghmour

P3668R4 CWG Approved

Defaulting Postfix Increment and Decrement Operations

Matthew Taylor, Alex (Waffl3x)

P3670R4 CWG Approved

Pack Indexing for Template Names

Corentin Jabot

P3847R1 CWG Approved

Lexical order for lambdas

S. Davis Herring

P3899R3 CWG Approved

Clarify the behavior of floating-point overflow

Jan Schultke, Matthias Kretz

P3950R1 CWG Approved

return_value & return_void Are Not Mutually Exclusive

Robert Leahy

P4271R0 CWG NewApproved

Core Language Working Group "ready" Issues for the June, 2026 meeting

Jens Maurer

P2019R9 LWG Approved

Thread attributes

Corentin Jabot

P2956R3 LWG

Add saturating library support to std::simd

Daniel Towner, Ruslan Arutyunyan

P3049R2 LWG

node-handles for lists

Michael Florian Hava

P3091R6 LWG Approved

Better lookups for `map` , `unordered_map`, and `flat_map`

Pablo Halpern

P3104R6 LWG Approved

Bit permutations

Jan Schultke

P3154R3 LWG Approved

Deprecating signed character types in iostreams

Elias Kosunen

P3242R4 LWG Approved

Copy and fill for mdspan

Nicolas Morales, Christian Trott, Mark Hoemmen, Damien Lebrun-Grandie

P3248R5 LWG Approved

Require [u]intptr_t

Gonzalo Brito Gadeschi

P3296R6 LWG

let_async_scope

Anthony Williams

P3319R6 LWG Approved

Add an iota object for simd (and more)

Matthias Kretz

P3395R6 LWG Approved

Fix encoding issues and add a formatter for std::error_code

Victor Zverovich

P3427R6 LWG

Hazard Pointer Synchronous Reclamation

Maged Michael, Michael Wong, Paul McKenney, Mark de Wever

P3505R4 LWG Approved

Fix the default floating-point representation in std::format

Victor Zverovich, Junekey Jeon

P3772R2 LWG Approved

std::simd overloads for bit permutations

Jan Schultke

P3785R1 LWG Approved

Library Wording Changes for Defaulted Postfix Increment and Decrement Operators

Matthew Taylor, Alex (Waffl3x)

P3791R1 LWG

constexpr deterministic random

Hana Dusíková

P3793R2 SG6LWG Approved