Toolchain reviews, AI policy, and a glibc scanf fix

Swift and LLVM lists dominated the day, with language-design reviews running alongside proposals to limit low-quality and AI-generated submissions. A glibc memory-safety fix, BFD linker hardening, and changes under discussion for Git and CPython rounded out the toolchain traffic.

Swift Evolution reviews Cell, ConstCell, and Volatile

SE-0556 is under review on the Swift forums, covering Cell, ConstCell, and Volatile. Discussion among 17 participants has focused on aliasing, Sendable, and C and C++ interop, which matters for code that shares mutable storage across Swift and foreign languages.

LLVM RFC would ban AI-generated project text

An LLVM RFC proposes forbidding AI-generated text in pull requests and RFCs, citing verbose, low-quality submissions that consume reviewer time. The thread is heated, with 65 participants and 129 messages, and a ban would change how contributions to the project are written and reviewed.

Glibc patch fixes wide scanf overflow

A glibc patch on libc-alpha fixes a one-byte write past the end in wide scanf conversions for %s and %[, tracked as BZ 34989 and CVE-2026-115819. The defect is a memory-safety bug in a core C library entry point, so distributors will want the fix once it lands.

LLVM considers open-PR caps for non-committers

A separate LLVM RFC proposes limits on open pull requests from non-committers, aimed at AI-generated patch floods and maintainer load. Thirty-four participants have weighed in, and the outcome would change how external contributors queue work.

Second pitch for Swift called-once function types

A second pitch proposes @once and @atMostOnce function types in Swift so closures can carry noncopyable and non-Sendable values. Twelve participants are discussing the design, which would tighten lifetime rules for one-shot callbacks.

BFD series hardens linker relaxation

A third revision of a patch series hardens 18 BFD ELF backends against memmove size underflow and heap corruption during in-place relaxation that deletes bytes. Memory corruption in that path can break links across many ELF targets, which is why the series is worth tracking.

Git patch would limit fetches from shallow remotes

A patch series on the Git list adds remote..fetchRefmap and limited-fetch behavior so a shallow repository need not fetch every branch. The 142-message thread, among six participants, centers on avoiding unnecessary ref traffic from shallow remotes.

CPython proposal: print() as one write()

A proposal and early pull request would change CPython print() to use a single write() call, with the stated aim of reducing interleaving when multiple threads print. Eleven participants are discussing the change on the Python discourse.