RepoJournal

$ cat rust-lang/month/2026-09-01.log

Rust

Rust

the month in review · September 2026

Rust lands GCA gates, wakes atomics, rust-analyzer v0.3.3049

By RepoJournal · composed from the cited sources · human-reviewed weekly · methodology

♥

September's through-line is groundwork: forced-keyword and GCA gates, volatile atomics in libcore, and rust-analyzer shipping twice.

3063 commits 682 PRs merged 5 releases 30 briefings covered

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2026-09-07 rust-lang/rust-analyzer

by github-actions[bot]

The v0.3.3041 release is the editor-side backbone of the month: it is the toolchain most of you actually type into, and its feature work lands through the rust-analyzer subtree sync into rustc, so the same server behavior shows up in nightly within days.

2026-09-14 rust-lang/rust-analyzer

by github-actions[bot]

v0.3.3049 followed a week later with the fixes half of the cycle, and the September 14 server also defaults to stable-only default members, so mixed-workspace editors stop pulling nightly-only members into analysis.

Rollup of 8 pull requests rust-lang/rust

by jhpratt

The rollup carrying the libcore change also modernizes the generic type parameter names on `Extend` and `FromIterator` and restores alias rigidity from HIR typeck in the borrow checker. The generic renames touch rustdoc output and any manually written trait impl documentation.

Rollup merge of #161971 - hanna-kruppe:rm-flag-satfpcast, r=RalfJung rust-lang/rust

by Jonathan Brouwer

The flag was added in 2017 to benchmark the then-experimental saturating semantics; saturation has since become the only behavior, so the switch no longer toggles anything. If it is still in your CI flags, this is the month it starts warning.

Add wcslen builtin rust-lang/compiler-builtins

by nicholasbishop

In LLVM 23 a loop optimization pass sometimes emits `wcslen` calls, which left some targets, UEFI among them, failing with a linker error whenever a loop got that treatment. Targets that previously wouldn't link should now build.

controllers/owners: Parse add-owner arguments before dispatch rust-lang/crates.io

by Turbo87

GitHub team parsing moves into a `GitHubTeamLogin` type and dispatch operates on a `Login` enum instead of raw strings, while unprefixed users and `github:org:team` keep working unchanged. This is a foundation refactor, not a behavior change, so token scopes and existing owners are unaffected.

Auto merge of #162117 - JonathanBrouwer:rollup-vMnIfR5, r=JonathanBrouwer rust-lang/miri

by bors

The 16-merge rollup includes `#[target_feature(enable = ...)]` support on `#[naked]` functions and the stabilization of smart pointer map functions. If you write hand-written assembly wrappers, the `naked` change is the one that reaches your crate.

Rollup merge of #162063 - Mark-Simulacrum:aarch64-ec2, r=Kobzol rust-lang/miri

by Jonathan Brouwer

The numbers in the rollup are the argument: dist-aarch64-linux drops from 2h25m ($2.03/build) on GHA to 1h ($1.38/build) on c9g.8xl. Fewer build dollars per artifact does not change your code, but it changes how often broken nightlies can be caught.

$ ls rust-lang/month/ # the briefings behind this review

Tue Sep 1 Bors gains config sanity check, libcore exposes volatile atomics Wed Sep 2 Rust drops saturating-cast flag, updates CI hardware, tracks crates.io Thu Sep 3 compiler-builtins adds wcslen for LLVM 23, crates.io streamlines owner handling Fri Sep 4 Rust fixes time-traveling UB, rolls back enum Debug change Sat Sep 5 rustup adds --check flag and toolchain pin, libc gains path constants Sun Sep 6 Closures become MaybeDangling, AArch64 SVE lands in inline asm Mon Sep 7 libc hardens config, rust-analyzer ships 2026-09-07 Tue Sep 8 rustc-perf adds tokio benchmark and frontend thread support Wed Sep 9 Rustc benchmarks get faster with shared target dirs and dropped serde threads Thu Sep 10 i686 Windows host tools retired, DiagCtxt API narrowed Fri Sep 11 Cargo pipelining groundwork lands in rustc, crates.io trims listing queries Sat Sep 12 crates.io hardens owner login parsing, rustc reworks custom MIR casts Sun Sep 13 Rust removes `type const`, crates.io registry ticks over Mon Sep 14 rust-analyzer ships stable-only default members, rustc drops its CacheCell aliases Tue Sep 15 docs.rs patches rustls security bug, cuts its own test and 404 costs Wed Sep 16 Rust drops d32 from 32-bit Arm, hir_typeck stops ICEing, GVN tightens provenance check Thu Sep 17 Const Range iteration, reexport chains fixed, TWiR 669 lands Fri Sep 18 crates.io rejects publish tarballs missing target sources Sat Sep 19 Miri picks up upstream Rust, compiler narrows query stack output Sun Sep 20 Cargo preserves locked prerelease deps, rustdoc fixes inlined intra-doc links Mon Sep 21 Polonius constraint passes get faster, RawVec drops Unique Tue Sep 22 docs.rs targets SQLite race conditions, crates.io drops legacy Prometheus metrics Wed Sep 23 Duration gets week/day/hour/minute constants, crates.io adds queue-age metrics Thu Sep 24 rustc rolls up 12 PRs as rustc_hir import cleanup spreads Fri Sep 25 rustc rebuilds incremental session dirs from scratch, crates.io logs auth identifiers before lock checks Sat Sep 26 GCA feature gates get final names, team reshuffles channel membership Sun Sep 27 Dropping an empty BTreeMap is free again, and SyncView stabilizes Mon Sep 28 Forced keywords land behind a feature gate Tue Sep 29 Span loses its ordering, MutTy disappears, libc ctest deprecates generate_test Wed Sep 30 docs.rs builds survive metrics failures, cargo picks up dotted-tuple config fix

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