› N5056 Business Plan and Convener's Report: ISO/IEC JTC 1/SC 22/WG 21 (C++) G. Davidson
2026-07-28
› P2249R7 Mixed comparisons for smart pointers G. D'Angelo
2026-07-22
Doc Date
2026-07-22
Abstract
Smart pointer classes are universally recognized as the idiomatic way to express ownership of a resource (very incomplete list: [Sutter], [Meyers], [R.20]). On the other hand, raw pointers (and references) are supposed to be used as non-owning types to access a resource.
› P2806R5 do expressions B. Revzin , B. Lopez , Z. Laine , M. Park
2026-08-13
Doc Date
2026-08-13
Abstract
We propose the addition of a new kind of expression, called a `do` expression. In its simplest form:
› P3100R8 A framework for systematically addressing undefined behaviour in the C++ Standard T. Doumler , J. Berne
2026-08-14
Doc Date
2026-08-14
Abstract
In this paper, we enumerate all cases of core language undefined behaviour explicitly specified in the C++ Standard, group them into ten categories, and classify them along a number of relevant criteria.
› P3139R2 Pointer cast for unique_ptr Z. Yuan , J. Saxonberg
2026-08-14
Doc Date
2026-08-14
Abstract
We propose `unique_ptr` overloads for `std::const_pointer_cast` and `std::dynamic_pointer_cast`. For each kind of cast, we allow users to choose between either using the defaulted deleter or preserving the original deleter type for each kind of cast.
› P3216R4 views::slice H. Kang
2026-07-27
Doc Date
2026-07-27
Abstract
This paper proposes the Tier 1 adaptor `views::slice` (as described in [P2760](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2760r1.html)) to enhance the C++29 ranges library. Notably, this is the first standard range adaptor that accepts two arguments — `start` and `end` — to specify the interval [`start`, `end`) for slicing a range.
› P3351R5 views::scan Y. Li
2026-08-12
Doc Date
2026-08-12
Abstract
The motivation for this view is given in [P2760R1] and quoted below for convenience:
› P3423R2 Extending User-Generated Diagnostic Messages Y. Li
2026-07-22
Doc Date
2026-07-22
Abstract
The first appearance of the compile-time message parameter in the C++ core language is in C++11, where `static_assert` declaration was introduced into the language by [N1720] with the syntax `static_assert(condition, message)`. At that time, the message parameter was the first time that users of the C++ language were able to control the generation of diagnostic messages in a dynamic way (excluding
› P3424R2 Define Delete With Throwing Exception Specification A. Meredith
2026-07-17
Doc Date
2026-07-17
Disposition Date
2026-06Adopted
Abstract
Throwing from an overloaded `delete` operator is undefined behavior, yet `delete` operators have a non-throwing exception specification by default, leading to a deterministic call to `terminate` before any undefined behavior can occur. This paper suggests we can do better than “undefined behavior” for the remaining cases.
› P3427R8 Hazard Pointer Synchronous Reclamation M. Michael , M. Wong , P. McKenney , M. Wever
2026-08-12
Doc Date
2026-08-12
Abstract
This paper proposes extending the C++26 hazard pointer interface to support synchronous reclamation. This revision, P3427R8, revises R7 by following LWG 2026-07-24 feedback. Ready for LWG review.
› P3589R3 C++ Profiles: The Framework G. Reis
2026-07-21
› P3817R0 Structured Binding Assignments Y. yonisimian@gmail.com , R. regev.ran@gmail.com
2026-07-28
Doc Date
2026-07-28
Abstract
This proposal introduces an extension to C++ structured bindings, allowing assignment to existing variables.
› P3904R3 When paths go WTF: making formatting lossless V. Zverovich
2026-08-12
Doc Date
2026-08-12
Abstract
[P2845], adopted in C++26, added formatting support for `std::filesystem::path`, addressing encoding issues and making formatting of a path as an ordinary (`char`) string lossless except for one case, unpaired surrogates on Windows. This paper proposes addressing this case and making such formatting lossless by default via the WTF-8 encoding ([WTF-8]). This will improve consistency in path handlin
› P3955R1 It's Scopes All the Way Down R. Leahy
2026-08-10
Doc Date
2026-08-10
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.
› P4049R1 Relaxing and extending std::copy G. D'Angelo
2026-07-30
Doc Date
2026-07-30
Abstract
In this table we’re summarizing the status quo and the changes brought by the options and extensions illustrated above. The table refers to `std::copy`, but similar changes are expected for the other algorithms of the family.
› P4130R0 SD-4: Five Correctives Inspired by ISO Directives V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
[SD-4](https://isocpp.org/std/standing-documents/sd-4-wg21-practices-and-procedures) [1] lets the convenor appoint every subgroup chair, set the meeting schedule, and declare consensus.
› P4199R0 A Reader's Guide to the August 2026 Mailing V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
Ten papers deliver a working profiles prototype covering seventy-seven cases of core-language undefined behavior with zero foundational wording changes, propose five governance correctives drawn verbatim from ISO Directives, and document how
› P4205R1 Range-Based Searchers Y. Li
2026-07-22
Doc Date
2026-07-22
Abstract
Current inconsistency in the `std::ranges::search` API forces users to exit the Ranges world to use searchers and resort to using traditional STL algorithms instead, which is undesirable.
› P4222R2 An initialization profile (R1) B. Stroustrup
2026-08-14
Doc Date
2026-08-14
Abstract
The initialization profile should be the easiest to define, but there can be no profile that everybody can agree on without discussion and alternative choices. Also, the rules for initialization and uninitialized memory are far more complex than most people are willing to believe. The initialization profile is foundational to just about every profile, so the initialization profile must isolate tho
› P4238R0 Returning C++26 for the Evaluation It Skipped V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
Contracts entered C++26 through procedural moves that broke no rule yet left no record of having reconciled the sustained technical opposition to the design.
› P4277R0 Overview and Implementation Report for P3100 J. Berne
2026-08-13
› P4282R1 Away From co_yield For std::execution::task R. Leahy
2026-08-02
Doc Date
2026-08-02
Abstract
The coroutine promise protocol shipped in C++20 not only banned `return_void` and `return_value` on the same promise type, but did so in an unusually restrictive manner [1]. Notably the aforementioned manner barred implementing the aforementioned mutual exclusion via mutually exclusive constraints.
› P4284R0 Addenda to the Undefined Behavior and IFNDR Annexes J. Berne
2026-08-13
› P4288R1 Stop the Decay R. Leahy
2026-07-31
Doc Date
2026-07-31
Abstract
`std::execution` can be thought of as the realization of the asynchronous analogue of a synchronous function [1][2]. The sender is the function itself (with all arguments selected and applied), the receiver is the channel by which the function communicates with its caller (in the synchronous realm by returning or throwing), and the operation state is the “stack” (i.e. a collection of variables wit
› P4294R1 views::take_last and views::drop_last H. Kang
2026-07-20
Doc Date
2026-07-20
Abstract
This paper proposes two new range adaptors, `views::take_last` and `views::drop_last`, that respectively produce the last *N* elements of a range and all-but-the-last *N* elements of a range. They mirror the shape of the existing `views::take` / `views::drop` adaptors and fill an obvious gap in the standard range adaptor set.
› P4297R1 Severing P3100's Profiles Claim from Its Case-by-Case Review V. Falco , V. Voutilainen
2026-08-14
Intent
Ask
Doc Date
2026-08-14
Abstract
This paper asks EWG (the Evolution Working Group) to sever an unadopted architecture claim from the wording it is bundled with, so that the wording proceeds and the claim gets its own paper and poll.
› P4302R1 Any Delegate May Object to a Poll on an Unmailed Revision V. Falco
2026-08-14
Intent
Ask
Doc Date
2026-08-14
Abstract
WG21 sometimes records polls on paper revisions that did not appear in a pre-meeting mailing. When an in-meeting revision changes the design, recording the poll can shift the consensus burden before national body experts have seen the change.
› P4306R1 Configuring Runtime Checking: Profiles and Implicit Contract Assertions V. Falco , V. Voutilainen
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
P3100R8 proposes that implicit contract assertions, configured through Contracts evaluation semantics and Labels, control runtime checking of core-language undefined behavior. The Profiles papers, P3589R2 and P3984R0, instead make a Profile the named mechanism that selects and defines such guarantees.
› P4308R1 Eight Responses to a Throwing Implicit Contract Assertion V. Falco , V. Voutilainen
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
The response space for a throwing implicit contract assertion contains at least eight options, not the four before EWG.
› P4310R1 Hasta la Vista, Undefined Behavior: Why std::core_ub Should Terminate by Default V. Falco , V. Voutilainen
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
`std::core_ub` (P4317R1) guards the runtime-checkable cases of core-language undefined behaviour and, when enforced, guarantees the check runs. It leaves one question open: after a guarded violation is detected, does the program continue or terminate? This paper answers terminate. Whether contracts are the right substrate for these checks at all is argued against them in P4332R0; this paper takes
› P4311R1 Getting a const element type version of an mdspan accessor, and of an mdspan too M. Hoemmen , R. Parolin
2026-08-14
Doc Date
2026-08-14
Abstract
Given an accessor `a` of type `A`, a “const element type version of `a`” (if it exists) is an accessor `b` of a possibly different type `B`, where
› P4313R1 Bitmask operations for enums I. Guterman , A. Williams
2026-07-21
Doc Date
2026-07-21
Abstract
As a developer coming from languages other than C++, I grew accustomed to using enums to represent flags. However, such behavior is noticeably absent from the C++ language.
› P4317R1 A Profile for Runtime-Checkable Core-Language Undefined Behavior: std::core_ub V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
P4297R1 [1] asks EWG to sever P3100R8's architecture claim from its case-by-case wording review. This paper demonstrates the severing is feasible.
› P4318R1 Transient Benefit, Perpetual Cost: Implicit Core-Language Assertions V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
Standardizing a continuing (log-and-continue) response for implicit contract assertions on core-language undefined behavior, as a portable guarantee every implementation carries, returns less than it costs.
› P4323R0 Do do_return! J. Schultke
2026-08-11
Doc Date
2026-08-11
Abstract
[[P2806R4]](https://wg21%2elink/p2806r4) proposed to let the user omit the last semicolon in a `do` expression to yield a result. This paper argues against that feature for a variety of reasons.
› P4324R0 Exploration of a more library-oriented approach to contracts V. Voutilainen , V. Voutilainen
2026-08-14
Doc Date
2026-08-14
Abstract
This paper supplies a design and implementation exploration for a more library-oriented approach to contracts.
› P4327R0 Direct-list-initialization syntax for default function arguments U. Radu-Andrei
2026-08-10
Doc Date
2026-08-10
Abstract
A parameter declaration may contain a braced-init-list immediately following the `declarator`.
› P4329R0 variant_sender R. Leahy
2026-07-29
Doc Date
2026-07-29
Abstract
Under the status quo of the C++29 working draft one can write asynchronous code which branches synchronously:
› P4330R0 Analysis of Contracts Papers V. Falco
2026-08-14
Intent
Inform
Doc Date
2026-08-14
Abstract
This paper examines select papers that propose to extend P2900 contracts. Each paper is evaluated through two lenses:
› P4332R0 Contracts are inappropriate for undefined behavior checks J. Spicer , V. Voutilainen , B. Stroustrup , V. Falco , J. Sanchez
2026-07-31
Doc Date
2026-07-31
Abstract
This document makes one narrow claim: that the mechanism P2900 defines for contract assertions is the wrong mechanism for checks whose purpose is to detect or mitigate core-language undefined behavior, as proposed by P3100. The claim does not depend on any hostile reading of contracts. It follows from what the contracts proposal says about itself: P3846R1 concedes that guaranteed enforcement is a
› P4334R0 P2900 Contracts’ fundamental flaws B. Stroustrup , J. Garcia , V. Falco , J. Spicer , V. Voutilainen
2026-08-14
› P4337R0 emplace_from R. Leahy
2026-08-03
Doc Date
2026-08-03
Abstract
Enabled by variadic templates and forwarding references, C++11 brought emplace construction. Containers, wrappers, et cetera could provide variadic constructors or functions which forwarded arguments through to a constructor of some wrapped or contained type thereby creating an instance of that type without intervening temporaries (which would be copied or moved from).
› P4338R0 deduce R. Leahy
2026-08-03
Doc Date
2026-08-03
Abstract
`emplace_from` is a proposed standard library class template which enables emplace functionality (e.g. `std::vector::emplace_back`, `std::optional::emplace`, et cetera) to be used to construct immovable types returned by factory functions (e.g. `std::execution::connect`).
› P4340R0 Extending constant template parameter support by customizing std::meta::reflect_constant B. Revzin
2026-08-13
Doc Date
2026-08-13
Abstract
This is a follow-up to [[P2484R0] (Extending class types as non-type template parameters)](https://wg21.link/p2484r0) and [[P3380R1] (Extending support for class types as non-type template parameters)](https://wg21.link/p3380r1) (the latter of which starts with a useful reading list), and is a new solution to that problem building upon three insights:
› P4343R0 Adding clear() to Container Adaptors S. Avasthi
2026-08-11
Doc Date
2026-08-11
Abstract
Currently, there is no standardized, zero-overhead way to clear the elements of container adaptors. When developers need to reuse a <ins>std::priority_queue or std::queue</ins> in a performance-critical loop, they are forced to use one of two suboptimal workarounds:
› P4344R0 pure alias types J. Waterloo
2026-08-13
Doc Date
2026-08-13
Abstract
By formalizing `pure alias types`, we remove seeming inconsistencies between references and other alias types. This will result in fewer instances of immediate dangling, return based dangling and superfluous aliasing.
› P4347R0 How to decouple UB-checks from Contracts V. Voutilainen
2026-08-14
Doc Date
2026-08-14
Abstract
This paper explains how to decouple UB-checks from Contracts. Because multiple people have expressed a desire to look at that. Further, this paper explains how to do that without redefining Undefined Behavior. This paper focuses on *how*. This paper doesn't focus on *why*.
› P4348R0 Types and Attributes B. Stroustrup
2026-08-14
Doc Date
2026-08-14
Abstract
```cpp The most important examples involve function calls that pass a pointer to initialized or uninitialized memory. Marking an argument with [[ref_to_uninit]] means that that argument must refer to uninitialized memory. If not, the initialization profile requires that that an argument refers to an initialized object. Consider int x [[uninit]]; using T = decltype(x); // does T accept a pointer to
