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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Updates from Rust Community

Official

• What do people love about Rust?
• Please submit 2026 Project goal proposals
• December 2025 Project Director Update
• Program management update — End of 2025
• Rustup 1.29.0 beta: Call for Testing!

Newsletters

• The Embedded Rustacean Issue #61
• Scientific Computing in Rust #13 (December 2025)

Project/Tooling Updates

• What's "new" in Miri (and also, there's a Miri paper!)
• cargo-coupling: Visualizing Coupling in Rust Projects
• Announcing Asterinas 0.17.0
• Tuitar - A portable guitar training tool & DIY kit
• Gitoxide in December
• Announcing GotaTun, the future of WireGuard at Mullvad VPN
• wgpu v28.0.0 - Mesh Shaders, Immediates, and More!
• rustc_codegen_gcc: Progress Report #39

Observations/Thoughts

• Syntactic musings on the fallibility effect
• Rust’s Block Pattern
• [audio] Netstack.FM episode 19 — Firezone and Zero-Trust Network Security with Thomas Eizinger

Rust Walkthroughs

• Rust Unit Testing: Basic HTTP Server
• Async Rust Bluetooth Plumbing: Where the Throughput Goes
• [series] Part 2: Tensor Operations, Building an LLM from Scratch in Rust

Crate of the Week

This week's crate is arcshift, an Arc replacement for read-heavy workloads that supports lock-free atomic replacement.

Thanks to rustkins for the 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.

• No calls for testing were issued this week by Rust, Cargo, Rust language RFCs or Rustup.

Let us know if you would like your feature to be tracked as a part of this list.

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.

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!

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.

• RustWeek 2026 | CFP closes 2026-01-18 | Utrecht, The Netherlands | 2026-05-19 - 2026-05-20
• RustConf 2026 | CFP closes 2026-02-16 | Montreal, Quebec, Canada | 2026-09-08 - 2026-09-10

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

475 pull requests were merged in the last week

Compiler

• add target_feature = "gc" for Wasm
• better closure requirement propagation
• correctly encode doc attribute metadata
• don't treat asserts as a call in cross-crate inlining
• improve filenames encoding and misc
• make closure capturing have consistent and correct behaviour around patterns
• support recursive delegation

Library

• add try_as_dyn and try_as_dyn_mut
• add const default for OnceCell and OnceLock
• expand str_as_str to more types
• make const BorrowMut require const Borrow and make const Fn require const FnMut
• hashbrown: add hash_map::{OccupiedEntry::into_entry, VacantEntryRef::insert_entry_with_key}, make EntryRef use ToOwned again
• hashbrown: add hash_table::OccupiedEntry::replace_entry_with to mirror HashMap API
• hashbrown: add hash_table::UnsafeIter, iter() method to various iterators

Rustdoc

• Add missing close tags in extern crate reexports
• Fix invalid handling of field followed by negated macro call
• generate macro expansion for rust compiler crates docs
• handle macro expansions in types

Clippy

• transmuting_null: Check const integer casts
• allow multiline suggestions in map-unwrap-or
• do not attempt to use nth with non-usize argument
• don't emit collapsible_else_if lint when all arms contain only if {} else {} expressions
• fix cmp_null missing parens in the example
• fix empty_enum_variants_with_brackets misses removing brackets in patterns
• fix if_then_some_else_none suggests wrongly when then ends with comment
• fix needless_type_cast suggesting invalid code for non-literal initializers
• fix println_empty_string suggestion caused error
• fix use_self false positive on type in const generics
• fix an incorrect error message regarding the size of usize and isize in cast_precision_loss
• move collapsible_else_if to pedantic
• new lint - same_length_and_capacity

Rust-Analyzer

• add 'Use of AI tools' section to CONTRIBUTING.md
• add BreakExpr completion suggest
• add an lsp extension to get failed obligations for a given function
• add default varname for TryEnum postfix completion
• add guess braces doc T![] for T_
• add ide-assist: add_explicit_method_call_deref
• complete reference &T → &&T
• introduce crate_attrs field in rust-project.json
• pretty print attributes up to cfg(false)
• fix applicable on non naked if for move_guard assist
• fix guess renamed macro braces
• fix indent for convert_iter_for_each_to_for
• fix indent for merge_nested_if
• fix match arm nested body invalid expected type
• fix nested if-let for merge_nested_if
• fix flycheck generations not being synced for multiple workspaces
• more perf improvements, made possible after non-Salsa interneds
• non-Salsa-interned solver types - with GC for them
• remove conflicting advice
• support undotted-self for this param closure

Rust Compiler Performance Triage

Very quiet week, with essentially no change in performance.

Triage done by @simulacrum. Revision range: 21ff67df..e1212ea7

1 Regression, 1 Improvement, 3 Mixed; 2 of them in rollups 36 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.

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

• Explicitly export core and std macros
• Stabilize 29 RISC-V target features (riscv_ratified_v2)

Cargo

• feat(toml): TOML 1.1 parse support

Compiler Team (MCPs only)

• Allow combining --help -C help -Z help -W help in one invocation

Leadership Council

• Raise travel grant limit to $100,000 for 2026
• Fund program management program for 2026
• Raise automatic travel grant to $2000

No Items entered Final Comment Period this week for Rust RFCs, 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

• Thin pointers with inline metadata

Upcoming Events

Rusty Events between 2025-12-24 - 2026-01-21 🦀

Virtual

• 2025-12-30 | Virtual (Tel Aviv-yafo, IL) | Code Mavens 🦀 - 🐍 - 🐪
  • Live Open Source Rust project contribution
• 2026-01-03 | Virtual (Kampala, UG) | Rust Circle Meetup
  • Rust Circle Meetup
• 2026-01-07 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2026-01-08 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
  • Meet, swap, and learn!
• 2026-01-08 | Virtual (Nürnberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2026-01-13 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Second Tuesday
• 2026-01-13 | Virtual | libp2p Events
  • rust-libp2p Open Maintainers Call
• 2026-01-15 | Virtual (Berlin, DE) | Rust Berlin
  • Rust Hack and Learn
• 2026-01-20 | Virtual (Washington, DC, US) | Rust DC
  • Mid-month Rustful
• 2026-01-21 | Virtual (Vancouver, BC, CA) | Vancouver Rust
  • Stack Safety

Asia

• 2026-01-07 | Tel Aviv-yafo, IL | Rust 🦀 TLV
  • In person Rust January 2026 at AWS in Tel Aviv

Europe

• 2026-01-07 | Amsterdam, NL | Rust Developers Amsterdam Group
  • Meetup @ Instruqt
• 2026-01-07 | Girona, ES | Rust Girona
  • Rust Girona Hack & Learn 01 2026
• 2026-01-08 | Geneva, CH | Post Tenebras Lab
  • Rust Meetup Geneva
• 2026-01-14 | Reading, UK | Reading Rust Workshop
  • Reading Rust Meetup
• 2026-01-20 | Leipzig, SN, DE | Rust - Modern Systems Programming in Leipzig
  • Topic TBD
• 2026-01-20 | Paris, FR | Rust Paris
  • Rust meetup #82

North America

• 2025-12-27 | Boston, MA, US | Boston Rust Meetup
  • Lechmere Rust Lunch, Dec 27
• 2026-01-03 | Boston, MA, US | Boston Rust Meetup
  • Allston Rust Lunch, Jan 3
• 2026-01-08 | Mountain View, CA, US | Hacker Dojo
  • RUST MEETUP at HACKER DOJO
• 2026-01-10 | Boston, MA, US | Boston Rust Meetup
  • Central Cambridge Rust Lunch, Jan 10
• 2026-01-15 | Seattle, WA, US | Seattle Rust User Group
  • Janurary, 2026 SRUG (Seattle Rust User Group) Meetup
• 2026-01-17 | Boston, MA, US | Boston Rust Meetup
  • Boston Common Rust Lunch, Jan 17
• 2026-01-20 | San Francisco, CA, US | San Francisco Rust Study Group
  • Rust Hacking in Person
• 2026-01-21 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground

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

they should just rename unsafe to C so people can shut up

– /u/thisismyfavoritename on /r/rust

Thanks to Brian Kung 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

Email list hosting is sponsored by The Rust Foundation

Discuss on r/rust