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? Tweet us at @ThisWeekInRust or send us a pull request. Want to get involved? We love contributions.

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Updates from Rust Community


Project/Tooling Updates


Rust Walkthroughs


Crate of the Week

This week's crate is bnum, a library of arbitrarily sized fixed-size numerals.

Thanks to Isaac Holt 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

416 pull requests were merged in the last week

Rust Compiler Performance Triage

A rather rough week for compiler performance with regressions outweighing improvements by a considerable margin, in particular in real world crates. To add insult to injury, the biggest regressions came in rollups which make it difficult to trace the cause.

Triage done by @rylev. Revision range: b3f4c311..8bd12e8


mean max count
Regressions 😿
1.5% 4.0% 176
Regressions 😿
1.8% 6.4% 147
Improvements 🎉
N/A N/A 0
Improvements 🎉
-1.6% -4.1% 9
All 😿🎉 (primary) 1.5% 4.0% 176

7 Regressions, 5 Improvements, 3 Mixed; 4 of them in rollups 48 artifact comparisons made in total

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.

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

  • No New or Updated RFCs were created this week.

Upcoming Events

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Quote of the Week

The long compile times where all responsibility is taken away from you is infinitely more effective than submission patterns in BDSM, where the graceful rustc takes over and all you have to do is wait until they tell you that you're a good person and that everything is alright!

/u/whyvitamins on /r/rust

Thanks to Jacob Pratt 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.

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