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 onlyerror, a #[derive(Error)] macro with support for no_std on nightly compilers.

Thanks to Jay Oster 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 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.

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

Updates from the Rust Project

450 pull requests were merged in the last week

Rust Compiler Performance Triage

A busy two weeks (as last week perf triage was not done). Overall improvements outweigh regressions with an average improvement of -2.6% across a large swath of the test cases. Of particular note was the move to use SipHash-1-3 instead of SipHash-2-4 for StableHasher which improved 184 benchmark tests by an average of 2.3%!

Triage done by @rylev. Revision range: 7c96e40..74864f


(instructions:u) mean range count
Regressions ❌
3.1% [0.2%, 24.4%] 11
Regressions ❌
4.9% [0.4%, 37.4%] 32
Improvements ✅
-2.9% [-20.4%, -0.3%] 205
Improvements ✅
-4.0% [-43.5%, -0.3%] 160
All ❌✅ (primary) -2.6% [-20.4%, 24.4%] 216

6 Regressions, 8 Improvements, 11 Mixed; 6 of them in rollups 119 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.


  • No RFCs entered Final Comment Period this week.

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:

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 2023-04-19 - 2023-05-17 🦀



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

Error types should be located near to their unit of fallibility.

Sabrina Jewson on her blog

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.

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