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 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.

Updates from Rust Community


Project/Tooling Updates


Rust Walkthroughs



Crate of the Week

This week's crate is async_fn_traits, a crate with async function traits to enable using higher ranked trait bounds in async functions.

Thanks to kornel for the 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

402 pull requests were merged in the last week

Rust Compiler Performance Triage

A very quiet week with the only large change in performance being improvements brought on by @saethlin's work on cleaning up the FileEncoder used in various places like rustc_metadata and rustc_serialize.

Triage done by @rylev. Revision range: af78bae..27b4eb9


(instructions:u) mean range count
Regressions ❌
0.6% [0.3%, 1.1%] 15
Regressions ❌
2.0% [0.2%, 7.1%] 32
Improvements ✅
-0.7% [-1.3%, -0.3%] 70
Improvements ✅
-0.9% [-3.5%, -0.2%] 31
All ❌✅ (primary) -0.4% [-1.3%, 1.1%] 85

2 Regressions, 3 Improvements, 4 Mixed; 0 of them in rollups 73 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:

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:

  • 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 2023-09-27 - 2023-10-25 🦀




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

The problem with Rust it appears,
that it leaves programmers in tears
if they have to go back
to languages that lack
in short they've got feature-arrears.

llogiq on /r/rust

Thanks to Frank Steffahn 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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Discuss on r/rust