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

• Rust code in Unreal Engine.
• Introduction - Roguelike tutorial.
• Towards a Rust foundation.
• Way Cooler postmortem.
• Why Rust? I have a GC!
• rust-analyzer changelog 7.
• This month in Rust gamedev 5 - December 2019.
• RDBC is moving to Tokio.
• Synthesizing loop-free programs with Rust and Z3.
• Containerized builds for Rust on the ESP32.
• Implementing a cooperative scheduler in a Rust kernel.

Crate of the Week

This week's crate is cxx, a library to build a C++ FFI safely by taking care of both sides.

Thanks to Ehsan M. Kermani for the suggestions!

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.

• [good first issue] sqlx: Add a proc macro derive for Encode and Decode supporting only 1-arity tuple structs with a mentor.
• Help port hyper and body-image-futio to async-std.

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

Updates from Rust Core

311 pull requests were merged in the last week

• prepare for LLVM 10 upgrade
• allow specifying LLVM args in target specifications
• don't require allow_internal_unstable unless staged_api is enabled
• more reductions in error handling diversity
• introduce X.., ..X, and ..=X range patterns
• ban ...X pats, harden tests, and improve diagnostics
• add suggestions when encountering chained comparisons
• handle multiple error fix suggestions carefully
• simplify into_key_slice_mut
• Option::{expect,unwrap} and Result::{expect, expect_err, unwrap, unwrap_err} have #[track_caller]
• add HashSet::get_or_insert_owned
• make Layout::new const
• constify more of alloc::Layout
• futures mpsc: split bounded and unbounded implementations
• distinguish between private items and hidden items in rustdoc
• rustbuild: add llvm-skip-rebuild flag to x.py

Approved RFCs

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

No RFCs were approved 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.

RFCs

• [disposition: merge] Introduce the ASM project group.
• [disposition: merge] Deprecate stdlib modules dedicated to numeric constants and move those constants to associated consts.

Tracking Issues & PRs

• [disposition: merge] Stabilize #![feature(slice_patterns)] in 1.42.0.
• [disposition: merge] Added From<Vec<NonZeroU8>> for CString.
• [disposition: merge] Relax bounds on HashMap/HashSet.
• [disposition: merge] Stabilize ptr::slice_from_raw_parts[_mut].
• [disposition: merge] Stabilize the debug_map_key_value feature.
• [disposition: merge] Tracking issue for core::iter::once_with().
• [disposition: merge] Tracking issue for ManuallyDrop::take.

New RFCs

• Inline assembly.

Upcoming Events

Europe

• Jan 17. Stuttgart, DE - Rust Hack and Learn.
• Jan 22. Wrocław, PL - Rust Wrocław Meetup #16.
• Jan 23. Paris, FR - Rust Paris meetup #49.
• Jan 23. Warsaw, PL - Rust Warsaw 3.
• Feb 2. Brussels, BE - Rust devroom @ FOSDEM.
• Jan 22. Berlin, DE - OpenTechSchool Berlin - Rust Hack and Learn.
• Jan 22. Hamburg, DE - Rust Hack & Learn January 2020.
• Jan 23. Zagreb, HR - impl Zagreb for Rust - Rust Meetup 2020/01: Uvod u lock-free Rust.
• Jan 29. Copenhagen, DK - Copenhagen Rust Hack Night #21.

North America

• Jan 22. Ann Arbor, MI, US - Ann Arbor Rust Meetup - Monthly Gathering.
• Jan 22. Vancouver, BC, CA - Vancouver Rust meetup.
• Jan 22. Portland, OR, US - PDXRust - PDX Rust Hack Night.
• Jan 27. Durham, NC, US - Triangle Rustaceans - Project Night & Lightning Talks.
• Jan 28. Dallas, TX, US - Dallas Rust - Last Tuesday.
• Jan 29. Chicago, IL, US - Chicago Rust Meetup - Byte Sized Rust - AWS Lambdas & Rust.
• Jan 29. Houston, TX, US - Houston Linux Users Group - Rust Study Group.

South America

• Jan 18. Sao Paulo, BR - Rust SP - Encontro Janeiro 2020.

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.

Rust Jobs

No jobs listed for this week.

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

Quote of the Week

@ZiCog: Does anyone have a 'no holds barred, unsafe or not' solution to the problem in Rust that can match C?

@kornel: Pipe the C version through c2rust :slight_smile:

@ZiCog: Yay! Rust now beats both Clang and GCC!

– ZiCog and Kornel on rust-users

Thanks to Jan Riemer for the suggestion!

Please submit quotes and vote for next week!

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

Discuss on r/rust.