This Week in Rust 669

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.

This Week in Rust is openly developed on GitHub and archives can be viewed at this-week-in-rust.org. If you find any errors in this week's issue, please submit a PR.

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• The Embedded Rustacean Issue #80

• Slint 1.18 Released

• Where Does Rust Belong on Arduino? If it belongs.
• CO3: Toward the Optimal FFI
• Why building a Rust LSP is hard · Rust Glancer
• Developing provably correct Rust code with Verus
• Principles for fast Tokio applications

• Trying to Make a Loop Auto-Vectorize
• Does Rust Support Inheritance? Yes, No, and Maybe, All in the Same File
• Shipping Rust static libraries without symbol collisions

• A visual guide to Rust async
• Rust Projects - Write a Redis Clone - Version 3.0.0
• Can You Use ESP32 as SWD Programmer for STM32 with Rust?
• Time and Panic Traps in WebAssembly: It Compiles, but It Crashes in the Browser
• One Lock to Rule Them All
• Operators of death: checked arithmetic in Rust
• Rust generics: from Static to Dynamic dispatch
• [video] Your First GPUI App - Building a Desktop UI in Rust

• Optimizing a single Clippy lint by 3133X

This week's crate is zenjpeg, a pure Rust JPEG encoder and decoder.

Thanks to Kornel for the suggestion!

Please submit your suggestions and votes for next week!

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

• Tracking Issue for trim-paths RFC 3127
• Testing Instructions

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.

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.

• No Calls for participation were submitted this week.

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!

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!

523 pull requests were merged in the last week

• garbage-collect old incremental compilation sessions
• less clones and more cleanup for rustc_builtin_macros
• perf: read hygiene data once when hashing syntax contexts
• use DenseBit for drop_live_at in liveness tracing
• use Box<[Word]> for word storage in DenseBitSet

• generalise (most) impls on Box
• implement Thread::os_id
• reserve items in Extend implementations
• stabilize Vec::from_fn
• stabilize core::mem::DropGuard
• stabilize unsafe_cell_access

• fix(git): For git cli, tell users what config we aren't forwarding on error
• fix(install): use packaged lockfile by default
• fix(trim-paths)!: unremap file in one JSON doc
• lower the lint level of manual_readme and non_kebab_case_bins to allow
• specify --edition in messages tests
• test: add more comprehensive workspace feature unification tests

• don't treat a raw identifier as a raw string prefix
• fix adjustment of max_width within macros
• reserve width for const when formatting inline const blocks

• map_clone: avoid suggestions after type-changing coercions
• fix collapsible_match suggesting wrongly for conditional compiled code
• enable manual_swap in const contexts

• cache macro-expanded roots when climbing ancestors
• do not fill unstable methods in "Implement default members"
• do not panic on json with invalid field name
• don't panic on doc comments attached to literal expressions
• fix hir::Type owner mismatches between anon consts
• fix panic when trait solver re-enters itself
• fix panic when we call impls_trait for self type of builtin derive impls for generic types
• stop at eager macro recursion overflow
• ide: fix doc comment offset calculation

There were almost no regressions this week, and several performance improvements! Though some of them were reverts of regressions from a previous week. #162422 improved the performance of Polonius, whose performance is getting closer to the previous NLL borrow checker.

Triage done by @Kobzol. Revision range: 656a9da1..20d35a3a

Summary:

0 Regressions, 5 Improvements, 5 Mixed; 2 of them in rollups 40 artifact comparisons made in total

Full report here.

Approved RFCs

Changes to Rust follow the Rust RFC (request for comments) process. These are the RFCs that were approved for implementation this week:

• No RFCs were approved this week.

Every week, the team announces the 'final comment period' for RFCs and key PRs which are reaching a decision. Express your opinions now.

Rust

• Stabilize debug_closure_helpers
• Additional NonZero conversions
• Implement Default for NumBuffer
• Allow elided ('static) lifetimes in thread_local!
• Stabilize funnel_shifts (including const)
• Stabilize mem::conjure_zst
• Stabilize Result::into_{ok,err}
• windows: stabilise inherit_handles
• rustc: Stabilize the WebAssembly wide-arithmetic feature
• Prevent mutating the global environment pointer in CommandExt::exec and opt to use execve and resolve path manually
• alloc: stabilise Allocator
• Disallow accesses through an Index projection when a sibling ConstantIndex projection has been moved out of
• Allow unary operand types to be inferred later

Cargo

• feat(config): Add build.profile, install.profile
• OUT_DIR is also set when running the program

Leadership Council

• Allow observers to participate during meetings
• Suggest discussing LC candidates with mods

No Items entered Final Comment Period this week for Rust RFCs, Compiler Team, Language Team, Language Reference or Unsafe Code Guidelines. 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

• Fix broken Zig link in RFC 3308 and typos across RFC texts

Rusty Events between 2026-09-16 - 2026-10-14 🦀

• 2026-09-16 | Hybrid (Vancouver, CA) | Vancouver Rust
  • Building a Rust GPU driver in the Linux kernel
• 2026-09-17 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
  • September, 2026 SRUG (Seattle Rust User Group) Meetup
• 2026-09-18 | Virtual | Rust Girona
  • Sessió setmanal de codificació / Weekly coding session
• 2026-09-20 | Virtual (Bengaluru, IN) | Embedded Rust Discord
  • Silicon Sundays 3
• 2026-09-20 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Rust Deep Learning: Third Sunday
• 2026-09-22 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Fourth Tuesday Rust Bookclub
• 2026-09-24 | Virtual (Berlin, DE) | Rust Berlin
  • Rust Hack and Learn
• 2026-09-24 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
  • Rust Cells — Interior Mutability from Rust Core to Tock OS
• 2026-09-29 | Virtual (London, UK) | Women in Rust
  • Lunch & Learn: Crates, Tips & Tricks Lightning Talks - Bring your ideas!
• 2026-09-30 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
  • Operating Systems Book Club: Segmentation and Introduction to Paging
• 2026-10-02 | Virtual | Rust Girona
  • Sessió setmanal de codificació / Weekly coding session
• 2026-10-04 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Rust Deep Learning: First Sunday
• 2026-10-06 | Virtual (London, UK) | Women in Rust
  • 👋 Community Catch Up
• 2026-10-07 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2026-10-08 | Virtual (Berlin, DE) | Rust Berlin
  • Rust Hack and Learn
• 2026-10-08 | Virtual (Nürnberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2026-10-10 | Virtual (Gdansk, PL) | Stacja IT Trójmiasto
  • [BEZPŁATNIE] Programowanie w języku Rust
• 2026-10-13 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Second Tuesday

• 2026-09-14 - 2026-09-16 | Berlin, DE | Oxidize 2026
  • Oxidize 2026
• 2026-09-17 | Dortmund, DE | Rust Dortmund
  • Rust Dortmund Meetup - From Segfault to Safety @DiWoDo
• 2026-09-22 | Prague, CZ | Rust Prague
  • Rust Meetup Prague @ Rockwell Automation
• 2026-09-24 | Aarhus, DK | Rust Aarhus
  • Talk Night at SkyTEM
• 2026-09-24 | Amsterdam, NL | Rust Developers Amsterdam Group
  • Rust Meetup @ BlockTech
• 2026-09-24 | Frankfurt, DE | Rust Rhein-Main
  • AI Agentic Coding
• 2026-09-26 | Stockholm, SE | Stockholm Rust
  • Ferris' Fika Forum #30
• 2026-09-28 | Augsburg, DE | Rust Meetup Augsburg
  • Rust Meetup #21: Maximilian Grauvogl & Marcel Fink - From Bits to Bugs: A Rust generator for SUIT Manifests and Structure-Aware Parser Fuzzing
• 2026-09-29 | Manchester, UK | Rust Manchester
  • Rust Manchester September Code Night
• 2026-09-30 | Basel, CH | Rust Basel
  • Rust Meetup #16 @ ERNI
• 2026-10-05 | München, DE | Rust Munich
  • Rust Munich 2026 / 3
• 2026-10-08 | Oslo, NO | Rust Oslo
  • Rust Hack'n'Learn at Kampen Bistro
• 2026-10-10 | Geneva, CH | Rust Geneva
  • Rust Meetup Geneva
• 2026-10-14 | Barcelona, ES | BcnRust
  • 22nd bcnrust session

• 2026-09-16 | Hybrid (Vancouver, CA) | Vancouver Rust
  • Building a Rust GPU driver in the Linux kernel
• 2026-09-16 | San Francisco, CA, US | Bay Area Rust
  • Bay Area Rust - Graphics Meetup
• 2026-09-17 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
  • September, 2026 SRUG (Seattle Rust User Group) Meetup
• 2026-09-17 | Mountain View, CA, US | Hacker Dojo
  • RUST MEETUP at HACKER DOJO
• 2026-09-19 | Boston, MA, US | Boston Rust Meetup
  • Boston Common Rust Lunch, Sep 19
• 2026-09-22 | Chicago, IL, US | Chicago Rust Meetup
  • Rust Happy Hour
• 2026-09-23 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2026-09-23 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2026-09-24 | Atlanta, GA, US | Rust Atlanta
  • Rust-Atl
• 2026-09-26 | Boston, MA, US | Boston Rust Meetup
  • Harvard Rust Lunch, Sep 26
• 2026-10-01 | Saint Louis, MO, US | STL Rust
  • Building a Minimal, Rootless Container in Rust
• 2026-10-03 | Boston, MA, US | Boston Rust Meetup
  • Alewife Rust Lunch, Oct 3
• 2026-10-08 | San Diego, CA, US | San Diego Rust
  • San Diego Rust October Meetup - Back in person!
• 2026-10-10 | Boston, MA, US | Boston Rust Meetup
  • Back Bay Rust Lunch, Oct 10
• 2026-10-14 | Los Angeles, CA, US | Rust Los Angeles
  • Rust LA October: AI & Rust w/ Oxen.AI & Origin Lab!

• 2026-09-29 | Barton, AU | Canberra Rust User Group
  • September Meetup

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.

Please see the latest Who's Hiring thread on r/rust

Every so often I am told about some maths fact that I can only assume someone went to prison for discovering

– Simon Buchan

Thanks to Chayim Refael Friedman 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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Discuss on r/rust