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

• Security advisory for crates.io, 2017-09-19.
• kennytm joins the Rust infrastructure team.
• How the RLS works.
• An RFC for a Tokio revamp.
• Rewriting a Java application in Rust.
• The impl period newsletter, week 1.
• This week in Rust docs 74.
• These weeks in dev-tools, issue 2.
• This week in Redox 29.
• [podcast] Request for explanation 11 - Cargo culting the build system. This week's topic is eRFC 2136 "Cargo build system integration".

Crate of the Week

This week's crate is rustbreak, a crate providing simple single-file storage to e.g. persist settings. Thank you, Dieter Konrad 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.

• Contribute to Rust's 2017 impl period.
• impl period opportunities: rustdoc.
• impl period opportunities: bindgen.
• Neon - a library for writing native Node.js modules is looking for contributors.
• imag - a personal information management suite needs help with 0.5.0 milestone.
• Help with expanding UNIC’s components for the Unicode Character Database.
• rsmt2 - library to interact with SMT-LIB 2 compliant solvers is looking for contributors.

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

Updates from Rust Core

157 pull requests were merged in the last week

• incr.comp.: Add new DepGraph implementation
• Use memoized hashes when hashing Fingerprint
• Don't visit the same unit multiple times (fixes perf regression)
• Make the fallback of generator resumption be unreachable instead of using return
• Include unary operator to span for ExprKind::Unary
• Make -Z borrowck-mir imply that EndRegion's should be emitted
• Move effect-checking to MIR
• Implement underscore lifetimes
• Add iterator method .rfold(init, function) the reverse of fold
• rustbuild: with --no-fail-fast, report the specific commands that failed
• Add clippy to toolstate.toml (one more step to a stable clippy)
• Compress most of spans to 32 bits (memory savings + modest speedup)
• Improve diagnostics when attempting to match tuple enum variant with struct pattern
• Stabilized vec_splice and modified splice tracking issue
• Record semantic types for all syntactic types in bodies
• --cap-lints allow switches off can_emit_warnings
• Forbid interpolated tokens in the HIR
• cargo_compile: iterate packages once, not three times
• Add pub visibility for methods as well
• Implement Copy/Clone for closures
• Refactor translation unit partitioning/collection as a query
• Correctly bubble up errors from libbacktrace
• Add Cow<str> → Box<Error> impls
• Add Duration::from_micros
• Only consider yields coming after the expressions when computing generator interiors
• Optimize drain_filter
• Improve how rustdoc warnings are displayed
• Require rlibs for dependent crates when linking static executables
• don't suggest placing use statements into expanded code
• add comparison operators to must-use lint
• Allow writing metadata without llvm
• only set non-ADT derive error once per attribute, not per trait (yay for more focused error messages)
• Add deref suggestion

New Contributors

• Basile Desloges
• Bob Sun
• James Tucker
• Lucas Morales
• Marcus Buffett
• P.Y. Laligand
• Romain Porte

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 2045: target_feature.
• RFC 2011: generic_assert: Make the assert! macro recognize more expressions.
• RFC 1990: Add external doc attribute to rustc.

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] Non-lexical lifetimes.
• [disposition: merge] Support defining C-compatible variadic functions in Rust.
• [disposition: merge] Add support to Cargo for alternative registries.
• [disposition: merge] Type privacy and private-in-public lints.
• [disposition: merge] eRFC: Cargo build system integration.
• [disposition: merge] Fallible collection allocation 1.0.
• [disposition: merge] Implicit caller location (third try to the unwrap/expect line info problem).
• [disposition: merge] Unsized rvalues.
• [disposition: postpone] Infer function signatures from trait declaration into 'impl's.
• [disposition: postpone] Tuple-based variadic generics.
• [disposition: postpone] 'fn lifetime ascription. Add a 'fn lifetime that is bound to the scope of the body of the current innermost function or closure.
• [disposition: postpone] Default struct field values.
• [disposition: postpone] Introduce Option::<&T>::borrowed.

New RFCs

No new RFCs were proposed this week.

Upcoming Events

• Sep 28. Mozilla Community Dresden - Rust Meetup.
• Sep 28. Seattle Rust Meetup.
• Sep 30 - Oct 1. RustFest Zürich.
• Sep 30. Rust Bangalore IO and Error Handling Workshop.
• Sep 30. Rust Mexico #8: Taller Introductorio a Rust y Rocket.
• Oct 2 - Oct 3. Impl Days at RustFest Zürich.
• Oct 4. Rust Community Team Meeting at #rust-community on irc.mozilla.org.
• Oct 4. Rust Documentation Team Meeting at #rust-docs on irc.mozilla.org.
• Oct 4. Rust Atlanta - Grab a beer with fellow Rustaceans.
• Oct 4. Rust Cologne - Open Space.
• Oct 4. OpenTechSchool Berlin - Rust Hack and Learn.
• Oct 5. Rust release triage.
• Oct 7. Rust Bangalore SQL Data Binding Workshop.
• Oct 11. Rust Community Team Meeting at #rust-community on irc.mozilla.org.
• Oct 11. Rust Documentation Team Meeting at #rust-docs on irc.mozilla.org.
• Oct 12. Rust Washington DC - Mid-month Rustful.
• Oct 12. Columbus Rust Society - Monthly Meeting.

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

• Rust developers at Æternity.
• Rust web developer - remote position.

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

Quote of the Week

A Box always holds exactly one thing, like a single large struct. A Vec holds zero to many things of exactly one type and can change over time. If you had to relate them, a Box is a Vec with one element that went to Neverland and forgot it could ever grow.

— /u/zzyzzyxx on reddit.

Thanks to /u/l-arkham for the suggestion.

Submit your quotes for next week!

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