Hello and welcome to another issue of This Week in Rust! Rust is a systems language pursuing the trifecta: safety, concurrency, and speed. 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.

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

News & Blog Posts

• regex 1.0 is released.
• nperf: A sampling CPU profiler for Linux written in Rust from Nokia.
• How to speed up the Rust compiler in 2018.
• Borrowing in async code.
• An alias-based formulation of the borrow checker.
• Writing an OS in Rust: Unit testing.
• How does dynamic dispatch work in WebAssembly?
• Rust pattern: Precise closure capture clauses.
• Embedded Rust experiments - Flipping some bits high on STM32VLDISCOVERY board.
• Introducing Sentry for Rust.
• Installing Rust offline.
• This week in Rust docs 103.
• This week in Rust and WebAssembly 001.
• The Embedded Working Group newsletter 4.
• CLI Working Group newsletter 3.
• [podcast] Rusty Spike Podcast - episode 27. Game development, GNOME, Facebook, and match-making.
• [podcast] New Rustacean: e023 – Traits deep dive, part 1.

Crate of the Week

This week's crate is imgref, a trivial Rust struct for interchange of pixel buffers with width, height and stride. Thanks to Willi Kappler for the suggestion!

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.

• Clippy has a lot of good first issues to get started.
• mutagen has more 'good first issues'.
• Get started with these beginner-friendly issues.
• [hard] tarpaulin: Link error with undefined reference to main on Arch. Tarpaulin is a code coverage tool for Rust projects.

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

Updates from Rust Core

140 pull requests were merged in the last week

• make incremental compilation thread-safe
• display correct unused field suggestion for nested struct patterns
• improve error message for #[repr(align=x)]
• don't ICE on tuple struct ctor with incorrect arg count
• warn on all erroneous constants
• warn on pointless #[derive] in more places
• better error message when trying to write default impls
• mark std::str::replace(n) as #[must_use]
• allow MIR borrowck to catch unused mutable locals
• allow #[inline] on closures
• rustc: emit uwtable for allocator shims
• make dump_{alloc,allocs,local}() no-ops when tracing is disabled
• implement LazyBTreeMap and use it in a few places
• speed up nearest_common_ancestor
• use FxHashMap in syntax_pos::symbol::Interner::intern
• make Vec::new a const fn
• fix ICE with erroneous impl Trait in a trait impl
• use enum for approximate suggestions
• core: fix overflow in int::mod_euc when self < 0 && rhs == MIN
• remove hack around comparisons of i1 values
• stabilize dyn trait
• stabilize std::hint::unreachable_unchecked
• compiletest: detect non-ICE compiler panics
• rustc_driver: catch ICEs on the main thread too
• add Cell::update
• treat repr(Rust) univariant fieldless enums as ZSTs
• std: inline DefaultResizePolicy::new
• cargo: add target directory parameter --target-dir
• docs: add "the Rustc book"

New Contributors

• Aaron Aaeng
• Irina Popa
• James Sanderson
• Pazzaz
• Philipp Hansch
• Ralf Biedert
• z4v1er

Approved RFCs

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

• RFC 2318: Custom test frameworks.

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. This week's FCPs are:

• [disposition: merge] Reserve try for try { .. } block expressions.
• [disposition: merge] Async/await notation for ergonomic asynchronous IO.
• [disposition: merge] Unreserve proc.

New RFCs

• Add Async trait and task system to libcore.
• Unreserve proc.
• Keyword unreservations (pure, sizeof, alignof, offsetof).
• throw expressions.

Upcoming Events

The community team is trying to improve outreach to meetup organisers. Please fill out their call for contact info if you are running or used to run a meetup.

• May 3. Utrecht, NL - Rust Workshop.
• May 6. Mountain View, US - Open Table / Icebreaker: what projects are you working on.
• May 7. Sydney, AU - Rust Sydney - Meetup 13.
• May 8. Helsinki, FI - Finland Rust-lang Group - May Rust meetup.
• May 8. São Paulo, BR - Encontro de Comunidades - Guru-SP e RustLangBR na TOTVS.
• May 8. Rust Community Content Subteam Meeting at #rust-content on irc.mozilla.org.
• May 9. Rust Community Team Meeting at #rust-community on irc.mozilla.org.
• May 9. Rust Events Team Meeting.
• May 10. Redwood City, US - Bay Area - Where "Self-Driving" Database Meets a "Rusty" Distributed Key-Value Store.
• May 10. Arlington, US - Rust DC - Learn+Try: parsing with nom.
• May 10. Columbus, US - Columbus Rust Society - Monthly Meeting.
• May 10. San Diego, US - San Diego Rust May Meetup.
• May 13. Mountain View, US - Open Table / Icebreaker: what projects are you working on.
• May 14. Seattle, US - Seattle Rust Monthly Meetup.
• May 16. Denver, US - Rust Boulder/Denver - Rust Denver May Meetup.
• May 16. Rust Community Team Meeting at #rust-community on irc.mozilla.org.
• May 16. Berlin, DE - OpenTechSchool Berlin - Rust Hack and Learn.
• May 16. Vancouver, CA - Rust Study/Hack/Hang-out night.
• May 17. Cambridge, GB - Cambridge Rust Meetup.
• May 27. Paris, FR - RustFest Paris 2018.

If you are running a Rust event please add it to the calendar to get it mentioned here. Email the Rust Community Team for access.

Rust Jobs

No jobs listed for this week.

Tweet us at @ThisWeekInRust to get your job offers listed here!

Quote of the Week

last time i talked to the infra team they made a bot to replace kennytm. i fear if I ask them to write a rust based unikernel with a custom os to host the docs they’ll actually do it

— @killercup on Twitter.

Thanks to skade for the suggestion!

Submit your quotes for next week!

This Week in Rust is edited by: nasa42 and llogiq.