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 on Twitter 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. If you find any errors in this week's issue, please submit a PR.

Updates from Rust Community




Project/Tooling Updates


Rust Walkthroughs


Crate of the Week

This week's crate is lazy_format, a lazy version of format! for more efficient composed string formatting operations.

Thanks to Nathan West for the self-suggestion!

Please submit your suggestions and votes for next week!

Call for Participation

Always wanted to contribute to open-source projects but didn't 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.

If you are a Rust project owner and are looking for contributors, please submit tasks here.

Updates from the Rust Project

320 pull requests were merged in the last week

Rust Compiler Performance Triage

Fairly quiet week with the only excitement coming from a nice improvement implemented by @nnethercote which fixed a pesky performance regressions in the linting system. This produced a 0.6% performance improvement across a large amount of the real world crates we test against.

Triage done by @rylev. Revision range: 9db224fc..109cccbe


(instructions:u) mean range count
Regressions ❌
0.2% [0.2%, 0.2%] 3
Regressions ❌
1.7% [0.3%, 3.3%] 11
Improvements ✅
-0.8% [-2.2%, -0.2%] 129
Improvements ✅
-1.2% [-4.4%, -0.1%] 97
All ❌✅ (primary) -0.7% [-2.2%, 0.2%] 132

2 Regressions, 2 Improvements, 4 Mixed; 3 of them in rollups 41 artifact comparisons made in total

See the full report for details.

Approved RFCs

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

New and Updated RFCs

Call for Testing

An important step for RFC implementation is for people to experiment with the implementation and give feedback, especially before stabilization. The following RFCs would benefit from user testing before moving forward:

  • No RFCs issued a call for testing this week.

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.

Upcoming Events

Rusty Events between 2022-12-14 - 2023-01-11 🦀




North America

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

Quote of the Week

... you can lead a horse to git but you cannot make it commit.

/u/kibwen on /r/rust

Thanks to Anton Fetisov for the suggestion!

Please submit quotes and vote for next week!

This Week in Rust is edited by: nellshamrell, llogiq, cdmistman, ericseppanen, extrawurst, andrewpollack, U007D, kolharsam, joelmarcey, mariannegoldin, bennyvasquez.

Email list hosting is sponsored by The Rust Foundation

Discuss on r/rust