February 2026 →

January 2026 Papers

A WG21 mailing is the month's batch of papers under committee review.

Paper Title Authors Audience Document Date Mailing Date Previous Version Disposition
Intent Informational
Published 2025-11-01
Author(s) Nina Ranns
Audience WG21
Abstract | Doc. No.: | N5022 | | --- | --- | | Date: | 2025-11-01 | | Reply to: | [Nina Dinka Ranns](mailto:dinka.ranns@gmail.com) |
Intent Proposal
Published 2026-01-13
Author(s) Herb Sutter
Audience WG21
Tracking issue View on GitHub
Intent Proposal
Published 2026-01-14
Author(s) Matthew Taylor, Arthur O'Dwyer
Audience EWGI
Tracking issue View on GitHub
Abstract Currently, [[dcl.fct.def.default]/2.5](https://eel.is/c++draft/dcl.fct.def.default#2.5) permits an explicitly defaulted special member function to differ from the implicit one by adding *ref-qualifiers*, but not *cv-qualifiers*.
Intent Proposal
Published 2026-01-12
Author(s) Andre Kostur, David Stone
Audience EWG, LEWG
Tracking issue View on GitHub
Intent Proposal
Published 2025-12-26
Author(s) Robert Leahy
Audience LEWG
Tracking issue View on GitHub
Abstract In broad terms a regular (i.e. synchronous) function call has access to two forms of storage throughout its lifetime (note that the “lifetime” of a regular function call is the time between the call thereto and the return therefrom):
Intent Proposal
Published 2026-01-09
Author(s) Barry Revzin
Audience CWG, LWG
Tracking issue View on GitHub
Abstract At the Sofia meeting, [[P2996R13] (Reflection for C++26)](https://wg21.link/p2996r13), [[P3394R4] (Annotations for Reflection)](https://wg21.link/p3394r4), [[P3293R3] (Splicing a base class subobject)](https://wg21.link/p3293r3), [[P3491R3] (`define_static_{string,object,array}`)](https://wg21.link/p349143), [[P3096R12] (Function Parameter Reflection in Reflection for C++26)](https://wg21.link/p30
Intent Proposal
Published 2026-01-05
Author(s) Eric Niebler
Audience SG1, LEWG, LWG
Tracking issue View on GitHub
Intent Proposal
Published 2026-01-13
Author(s) Christof Meerwald
Audience EWG
Tracking issue View on GitHub
Abstract [CWG 3003](https://cplusplus.github.io/CWG/issues/3003.html) "Naming a deducible template for class template argument deduction" has been raised to clarify that with the current core language wording, class template argument deduction does not work for type template template parameters.
Intent Proposal
Published 2026-01-16
Author(s) Inbal Levi, Fabio Fracassi, Andreas Weis, Nevin Liber, Billy Baker, Corentin Jabot
Audience LEWG
Tracking issue View on GitHub
Abstract In 2025-10, the C++ Library Evolution group conducted a series of electronic decision polls [[P3872R0]](https://wg21.link/P3872r0). This paper provides the results of those polls and summarizes the results.
Intent Proposal
Published 2026-01-14
Author(s) Darius Neațu, Andrei Alexandrescu, Lucian Radu Teodorescu, Radu Nichita, Herb Sutter
Audience SG21, EWG
Revisions R1
Tracking issue View on GitHub
Abstract Building on motivation from EWG Kona 2025, this paper proposes a minimal pure extension to the C++26 Contracts facility. This extension addresses the Romanian National Body's (NB) concern by enabling the writing of an individual contract assertion that guarantees the program execution will not continue past the contract assertion if it is violated, regardless of the semantics of other contract ass
Intent Proposal
Published 2026-01-14
Author(s) Eric Niebler
Audience SG1, LEWG, LWG
Tracking issue View on GitHub
Intent Proposal
Published 2026-01-14
Author(s) Dietmar Kühl
Audience SG1, LEWG, LWG
Tracking issue View on GitHub
Abstract There are a few NB comments raised about the way `affine_on` works:
Intent Proposal
Published 2025-12-21
Author(s) Robert Leahy
Audience SG1, EWGI, EWG
Tracking issue View on GitHub
Abstract The standard specifies the effect of `co_return` statements in terms of equivalent statements within the context of a *replacement body* (§9.6.4 [dcl.fct.def.coroutine]). Like a regular `return` statement `co_return` statements have two distinct forms: Those that return `void` and those that return some value. These are specified as follows (§8.8.5 [stmt.return.coroutine]):
Intent Proposal
Published 2026-01-01
Author(s) Barry Revzin
Audience EWG
Tracking issue View on GitHub
Abstract The `std::format` approach to formatting offers many significant benefits over the prior `<iostream>`s approach that need not be revisited here. However, `<iostream>` does still have one significant advantage: ordering. It is easy to see at a glance with a long `std::cout` statement which pieces are to be formatted in which order. With `std::format`, as the amount of replacement fields increases,
Intent Proposal
Published 2026-01-08
Author(s) Herb Sutter, Glen Joseph Fernandes
Audience EWG, LEWG
Tracking issue View on GitHub
Abstract WG21 is often asked for a way to reliably answer the question, “does this raw pointer point inside this buffer?” See [Core 2025] for some use cases. Such an `is_pointer_in_range` function is appropriate to standardize because:
Intent Proposal
Published 2025-12-28
Author(s) Victor Zverovich
Audience LEWG
Tracking issue View on GitHub
Abstract [P2918] introduced `std::runtime_format` to allow opting out of compile-time format string checks in `std::format`. Subsequently, [P3391] made `std::format` usable in constant evaluation. As a result, `std::runtime_format` can now be evaluated at compile time, making its name misleading. This paper proposes renaming `std::runtime_format` to `std::dynamic_format` to better reflect its semantics and
Intent Proposal
Published 2026-01-14
Author(s) Robert Leahy
Audience SG1, LEWG
Tracking issue View on GitHub
Abstract The fundamental scope algorithm is `within`. It establishes a scope by running an enter scope sender. Thereafter it allows a child operation to run (in that scope since the exit scope sender has not yet run), and then before completing the overall operation runs the exit scope sender yielded by the enter scope sender.
Intent Proposal
Published 2026-01-08
Author(s) Mark Hoemmen, Jacob Faibussowitsch, Christian Trott
Audience LEWG
Tracking issue View on GitHub
Abstract We propose to change `layout_stride::mapping`’s constructors to permit strides to be zero if one or more extents are zero. For example, for extents (3, 5, 0, 11), this change would permit any nonnegative strides. Currently, users would need to set the stride(s) corresponding to zero extents to an arbitrary positive value, such as 1. That would make the strides (1, 3, 1, 105) in this example.
Intent Proposal
Published 2026-01-15
Author(s) Mark Hoemmen, Ruslan Arutyunyan
Audience SG1, EWGI, EWG, LEWG
Tracking issue View on GitHub
Abstract Given an object `src` of trivially-copyable type `T`, we can copy the object’s value representation to an array of bytes, and implicitly create a new `T` object (e.g., with `start_lifetime_as`) in the array of bytes. The result will hold the same value as `src`.
Intent Proposal
Published 2026-01-16
Author(s) Zhihao Yuan
Audience LEWG
Tracking issue View on GitHub
Abstract RU-220 calls for allowing skipping indirections when constructing `function_ref` to improve codegen. The proposed change in LWG 4264<sup>[1]</sup> is not strictly an optimization because certain behaviors with and without the change are visible, therefore, need to be made unspecified. This paper (P3961) suggests that, in addition to the change, a subset of the "optimized" cases should be mandated.
Intent Proposal
Published 2026-01-13
Author(s) Nina Ranns
Audience WG21
Tracking issue View on GitHub
Abstract As a committee, we have a shared goal: maintaining a standard that delivers real value to users while remaining implementable, performant, and portable. Our intention is to start a series of conversations about constructive steps we can take as a group toward narrowing the gap between standardization and implementation. We would like to see discussion about improving early communication, making co
Intent Proposal
Published 2026-01-15
Author(s) Ruslan Arutyunyan
Audience EWGI, EWG
Tracking issue View on GitHub
Abstract This paper proposes making lambdas with captures copy assignable and move assignable when all captured entities are themselves assignable.
Intent Proposal
Published 2026-01-16
Author(s) Inbal Levi, Fabio Fracassi, Andreas Weis, Billy Baker, Nevin Liber, Corentin Jabot
Audience WG21
Tracking issue View on GitHub
Abstract This paper contains the decision polls that the C++ Library Evolution group will take in January 2026.
Intent Proposal
Published 2026-01-16
Author(s) Bengt Gustafsson
Audience EWGI, SG21
Tracking issue View on GitHub
Intent Proposal
Published 2026-01-16
Author(s) Bengt Gustafsson
Audience EWGI, SG21
Tracking issue View on GitHub