Hello and welcome to another issue of This Week in Rust! Rust is a programming language empowering everyone to build reliable and efficient software. This is a weekly summary of its progress and community. Want something mentioned? Tag us at @thisweekinrust.bsky.social on Bluesky or @ThisWeekinRust on mastodon.social, or send us a pull request. Want to get involved? We love contributions.
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Updates from Rust Community
Official
Foundation
Newsletters
Project/Tooling Updates
Observations/Thoughts
- Microcontrollers with good support for Rust
- What Does a Governed Data Runtime Cost? TeaQL vs Diesel and SeaORM on MusicBrainz
- Stabilizing Rust's never type
- Searching through 150 GiB of Text per Second with SIMD
- Nine Rules for Compile-Time Work with Rust
const fn: Parse files, build tables, and catch mistakes … without a build script (Part 2) - A Design Space Exploration of Async/Await
- Rust: When Empty Isn't Bottom
Rust Walkthroughs
- What Rust's +simd128 Actually Changed in My WebAssembly
- Rust Control Flow in Practice - Build a Number Guessing Game
- Unsizing unsized values
- Game architecture
- Introducing CUDA Rust: Two Tracks for Writing GPU Kernels
- The State of Allocators in 2026 - 6 Months Later
- Visualizing Rust's Vtables: How dyn Trait Works In Memory
- Safely generating legal chess moves at 475,000,000 nodes/s
- Speeding up gearhash on ARM64 (2× faster)
- Let's build a compressor from scratch
- Reverse engineering my e-scooter and rewriting the firmware in rust
- Gloo + Yew for persistent webapp state
Miscellaneous
Crate of the Week
This week's crate is tokio-rcu, a user-space RCU implementation specifically built around the semantics of async rust and tokio.
Thanks to Roee Shoshani for the self-suggestion!
Please submit your suggestions and votes for next week!
Calls for Testing
An important step for RFC implementation is for people to experiment with the implementation and give feedback, especially before stabilization.
If you are a feature implementer and would like your RFC to appear in this list, add a
call-for-testing label to your RFC along with a comment providing testing instructions and/or guidance on which aspect(s) of the feature need testing.
Cargo
No calls for testing were issued this week by Rust, Rustup or Rust language RFCs.
Let us know if you would like your feature to be tracked as a part of this list.
RFCs
Rust
Rustup
If you are a feature implementer and would like your RFC to appear on the above list, add the new call-for-testing
label to your RFC along with a comment providing testing instructions and/or guidance on which aspect(s) of the feature
need testing.
Call for Participation; projects and speakers
CFP - Projects
Always wanted to contribute to open-source projects but did not know where to start? Every week we highlight some tasks from the Rust community for you to pick and get started!
Some of these tasks may also have mentors available, visit the task page for more information.
- sysknife - action_reference_doc_is_current prints two 44 KB documents instead of the line that differs
- sysknife - packages/setup claims Node 18 support, and Node 18 has been end-of-life since 2025-04-30
- sysknife - cargo test fails intermittently on main: a test sets a process-global env var
If you are a Rust project owner and are looking for contributors, please submit tasks here or through a PR to TWiR or by reaching out on Bluesky or Mastodon!
CFP - Events
Are you a new or experienced speaker looking for a place to share something cool? This section highlights events that are being planned and are accepting submissions to join their event as a speaker.
- No Calls for papers or presentations were submitted this week.
If you are an event organizer hoping to expand the reach of your event, please submit a link to the website through a PR to TWiR or by reaching out on Bluesky or Mastodon!
Updates from the Rust Project
613 pull requests were merged in the last week
Compiler
- always rerun if we normalize local opaques
- optimize empty token streams
- store LiveLoans more densely packed
- use IndexVec instead of BTreeMap for polonius variances
Library
- add custom allocator support to
(try_)maponUniqueArcandUniqueRc - box: fixup
map/try_mapdeallocate calls - stabilize smart pointer map functions
Cargo
docs(lints): how to configure Cargo lintsdocs(trim-paths): add limitations and polishdocs(trim-paths): workspace remap begins with.fix(git): Apply pr hint to git-fetch-with-clifix(git): Make PR dep note cloer to our style guidefix(git): Simplify error messagefix(git): Use git's 429 retry, when availablefix(parser): Resolve theoretical use-after-free- avoid passing search path (-L) args when they are passed as --extern
- docs: switch from "target triple" to "target tuple"
- fix relative symlink handling in
write_atomic - fix(trim-paths)!: limit options to
none|object|all - fix(trim-paths)!: remove default scope from release profile
- fixed stale comment about fingerprint checking method
Rustdoc
Rustfmt
- fix non-idempotent block doc comment closer rewrite
- prevent infinite loops when parsing items from
cfg_select!arms
Clippy
unnecessary_self_imports: lint nested importslegacy_numeric_constants: make fixes machine-applicablestd_instead_of_core: don't suggest a path that does not resolveuseless_conversion: ignoreFrom::fromin generated codeuseless_format: improve suggestionregex_creation_in_loops: check MIR loop structure- check that intra-doc links are not broken
- detect integration tests in
is_in_test - do not trigger
integer_division_remainder_usedin macros - improve
map_unwrap_orlint to supportmap(f).unwrap_or_default() - move the
clippy_ci_panic_testintegration into a regular test - respect inline allows in
needless_pass_by_value - soft rename
clippy::alltoclippy::default
Rust-Analyzer
- add diagnostics for missing bodies for free and associated items
- fix
NamedTempFileconstructors - accept Self as non-leading path segment in attribute paths
- allow inner attributes on blocks in tuple expressions
- avoid type unification errors in term search
- fix handling of
#[unsafe()]attrs without inner meta - fix parsing of
self:: in fn param list - hover
1f64use float instead of integer - follow symlinks when scanning the sysroot for proc-macro dylibs
- install cargo tools with locked dependencies
- merge
hir_def::hir::Expr::UnsafeintoExpr::Block - render const value in completions label details
Rust Compiler Performance Triage
This week we've hit quite a few regressions, both expected and unexpected.
One of them has already been fixed, with fixes for a few others being discussed.
One big improvement comes from caching the sanitizer set in Session, which fixes a large regression from last week.
A few minor improvements landed, including a 75% reduction in memory usage while compiling bevy_render with the next trait solver.
Triage done by @JonathanBrouwer. Revision range: 5321a4f4..656a9da1
Summary:
| (instructions:u) | mean | range | count |
|---|---|---|---|
| Regressions ❌ (primary) |
0.5% | [0.1%, 1.3%] | 121 |
| Regressions ❌ (secondary) |
0.6% | [0.1%, 10.3%] | 106 |
| Improvements ✅ (primary) |
-0.6% | [-1.9%, -0.1%] | 63 |
| Improvements ✅ (secondary) |
-0.6% | [-2.4%, -0.1%] | 65 |
| All ❌✅ (primary) | 0.1% | [-1.9%, 1.3%] | 184 |
3 Regressions, 2 Improvements, 8 Mixed; 6 of them in rollups 33 artifact comparisons made in total
Calls for Testing
An important step for RFC implementation is for people to experiment with the implementation and give feedback, especially before stabilization.
If you are a feature implementer and would like your RFC to appear in this list, add a
call-for-testing label to your RFC along with a comment providing testing instructions and/or guidance on which aspect(s) of the feature need testing.
Cargo
No calls for testing were issued this week by Rust, Rustup or Rust language RFCs.
Let us know if you would like your feature to be tracked as a part of this list.
Approved RFCs
Changes to Rust follow the Rust RFC (request for comments) process. These are the RFCs that were approved for implementation this week:
- Rustdoc LaTeX math
- RFC: Cargo feature descriptions
- Change
i686-pc-windows-msvcfrom Tier 1 with host tools => Tier 1 without host tools
Final Comment Period
Every week, the team announces the 'final comment period' for RFCs and key PRs which are reaching a decision. Express your opinions now.
Tracking Issues & PRs
Rust
- riscv: stabilize 'd' and 'f' target features
- x86: on targets that requires SSE, use those registers for ABI
- Re-export
core::fmt::NumBufferinalloc(andstd) - fix: unfulfilled nested dead code lint
- turn aligned-in-packed error into lint
- Guarantee 8 bytes of alignment of RawWakerVTable
- libtest: Allow passing --test-threads and --color multiple times, with later arguments overriding earlier
- Stabilize
core::mem::DropGuard
Cargo
Language Reference
Unsafe Code Guidelines
No Items entered Final Comment Period this week for Rust RFCs, Compiler Team, Language Team or Leadership Council. Let us know if you would like your PRs, Tracking Issues or RFCs to be tracked as a part of this list.
New and Updated RFCs
- No New or Updated RFCs were created this week.
Upcoming Events
Rusty Events between 2026-09-09 - 2026-10-07 🦀
Virtual
- 2026-09-09 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- 2026-09-10 | Virtual | Rust 🦀 Maven
- 2026-09-10 | Virtual (Berlin, DE) | Rust Berlin
- 2026-09-10 | Virtual (Nürnberg, DE) | Rust Nuremberg
- 2026-09-15 | Virtual (Washington, DC, US) | Rust DC
- 2026-09-16 | Hybrid (Vancouver, CA) | Vancouver Rust
- 2026-09-17 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
- 2026-09-18 | Virtual | Rust Girona
- 2026-09-20 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
- 2026-09-22 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
- 2026-09-24 | Virtual (Berlin, DE) | Rust Berlin
- 2026-09-24 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- 2026-09-29 | Virtual (London, UK) | Women in Rust
- 2026-10-02 | Virtual | Rust Girona
- 2026-10-04 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
- 2026-10-06 | Virtual (London, UK) | Women in Rust
- 2026-10-07 | Virtual (Indianapolis, IN, US) | Indy Rust
Europe
- 2026-09-10 | Geneva, CH | Rust Geneva
- 2026-09-14 - 2026-09-16 | Berlin, DE | Oxidize 2026
- 2026-09-15 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
- 2026-09-15 | Madrid, ES | MadRust
- 2026-09-17 | Dortmund, DE | Rust Dortmund
- 2026-09-22 | Prague, CZ | Rust Prague
- 2026-09-24 | Aarhus, DK | Rust Aarhus
- 2026-09-24 | Amsterdam, NL | Rust Developers Amsterdam Group
- 2026-09-24 | Frankfurt, DE | Rust Rhein-Main
- 2026-09-28 | Augsburg, DE | Rust Meetup Augsburg
- 2026-09-29 | Manchester, UK | Rust Manchester
- 2026-09-30 | Basel, CH | Rust Basel
- 2026-10-05 | München, DE | Rust Munich
North America
- 2026-09-08 - 2026-09-11 | Hybrid (Montreal, CA) | RustConf 2026
- 2026-09-09 | Montreal, CA | Women in Rust
- 2026-09-10 | Lehi, UT, US | Utah Rust
- 2026-09-10 | San Diego, CA, US | San Diego Rust
- 2026-09-12 | Boston, MA, US | Boston Rust Meetup
- 2026-09-15 | San Francisco, CA, US | San Francisco Rust Study Group
- 2026-09-16 | San Francisco, CA, US | Bay Area Rust
- 2026-09-16 | Hybrid (Vancouver, CA) | Vancouver Rust
- 2026-09-17 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
- 2026-09-17 | Mountain View, CA, US | Hacker Dojo
- 2026-09-19 | Boston, MA, US | Boston Rust Meetup
- 2026-09-23 | Austin, TX, US | Rust ATX
- 2026-09-24 | Atlanta, GA, US | Rust Atlanta
- 2026-09-26 | Boston, MA, US | Boston Rust Meetup
- 2026-10-01 | Saint Louis, MO, US | STL Rust
- 2026-10-03 | Boston, MA, US | Boston Rust Meetup
Oceania
- 2026-09-29 | Barton, AU | Canberra Rust User Group
If you are running a Rust event please add it to the calendar to get it mentioned here. Please remember to add a link to the event too. Email the Rust Community Team for access.
Jobs
Please see the latest Who's Hiring thread on r/rust
Quote of the Week
The Demon has access to a Super Turing Machine.
Thanks to Theemathas for the suggestion!
Please submit quotes and vote for next week!
This Week in Rust is edited by:
- nellshamrell
- llogiq
- ericseppanen
- extrawurst
- U007D
- mariannegoldin
- bdillo
- opeolluwa
- bnchi
- KannanPalani57
- tzilist
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