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.

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

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	3
Regressions ❌ (secondary)	1.7%	[0.3%, 3.3%]	11
Improvements ✅ (primary)	-0.8%	[-2.2%, -0.2%]	129
Improvements ✅ (secondary)	-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:

Support upcasting of dyn Trait values

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.

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 🦀

Virtual

2022-12-14 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2022-12-24 | Virtual (Linz, AT) | Rust Linz
- Rust Meetup Linz - 28th Edition
2022-12-14 | Virtual (México City, MX) | Rust MX
- Rust y Arduino
2022-12-15 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2022-12-20 | Virtual (Berlin, DE) | Berlin.rs
- Rust Hack and Learn
2022-12-20 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful
2022-12-21 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Show & Tell: Tableturf
2022-12-27 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-01-03 | Virtual (Beijing, CN) | WebAssembly and Rust Meetup (Rustlang)
- Monthly WasmEdge Community Meeting, a CNCF sandbox WebAssembly runtime
2023-01-03 | Virtual (Berlin, DE) | OpenTechSchool Berlin
- Rust Hack and Learn
2023-01-03 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- Buffalo Rust User Group, First Tuesdays
2023-01-04 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-01-04 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-01-05 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- Part 2: Exploring USB with Rust

Asia

2022-12-29 | Tel Aviv, IL | Rust TLV
- December Edition - xtask, macros and low level features

Europe

2022-12-14 | Trondheim, NO | Rust Trondheim
- Rust Advent of Code hackathon
2022-12-15 | Stuttgart, DE | Rust Community Stuttgart
- OnSite Meeting

North America

2022-12-14 | Austin, TX, US | Rust ATX
- Rust Lunch
2022-12-20 | San Francisco, CA, US | San Francisco Rust Study Group
- Rust Hacking in Person
2022-12-27 | Austin, TX, US | ATX Rustaceans
- Atx Rustaceans Meetup
2023-01-05 | Lehi, UT, US | Utah Rust
- Interesting Title and Food!

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.