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

No official blog posts, newsletters, or research papers this week.

Project/Tooling Updates

• rust-analyzer Changelog #78
• This Week In TensorBase 4
• rustc_codegen_gcc can now run libcore’s tests and pass most of them!
• Parcel 2 beta 3
• Announcing lettre 0.10.0-rc.1
• Announcing typed-sql beta! Zero-cost ORM with fast compile times
• Announcing Valuable, a library for object-safe value inspection

Observations/Thoughts

• Why and how we wrote a compiler in Rust (blog post series 1/X): the context
• 2D Web Rendering with Rust
• A fast-to-sync/search and space-optimized replication algorithm written in Rust, the gun-db data replication model
• Adventures in rustc Forking
• Baseline implementations should be predictable
• Naming Your Lifetimes
• Rucredstash release & Rust experience from a Haskeller

Rust Walkthroughs

• Creating an Infinite Mixture Model in Rust with the rv crate
• Debug rust application inside container
• Write Rust lints without forking Clippy
• Zig Makes Rust Cross-Compilation Just Work
• Routing traffic in Rust using eBPF
• How to to_string in Rust
• Building small desktop apps with Ember.js and Tauri
• Coming to Rust from Django
• Structural Typing in Rust
• Idiomatic Rust? Implementing binary search
• [ZH] Practice of web crawling with async Rust (使用 Rust 做异步数据采集的实践)
• [video] Lock-Free to Wait-Free Simulation in Rust

Miscellaneous

• Rust Web Development - MEAP
• Fuchsia OS partially written in Rust has shipped

Crate of the Week

This week's crate is typed-index-collections, a crate that lets you make Vecs with custom-typed indices.

Thanks to Tim for the nomination

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.

No issues were proposed for CfP.

Updates from Rust Core

280 pull requests were merged in the last week

• implement more Iterator methods on core::iter::Repeat
• override clone_from for some types
• stabilize const_fn_unsize
• implement the new desugaring from try_trait_v2
• impl FromStr for proc_macro::Literal
• stabilize extended_key_value_attributes
• fix auto-hide for implementations and implementors
• add rustc_mir::interpret::Machine::enforce_abi()
• check for more things in THIR unsafeck
• suppress spurious errors inside async fn
• avoid zero-length memcpy in formatting
• always produce sub-obligations when using cached projection result
• CTFE core engine allocation & memory API improvemenets
• CTFE get_alloc_extra_mut: also provide ref to MemoryExtra
• fix missing lifetimes diagnostics
• suggest borrowing if a trait implementation is found for &/&mut T
• remove InPlaceIterable marker from Peekable due to unsoundness
• extend rustc_on_implemented to improve more ? error messages
• cargo: add cargo:rustc-link-arg-bin flag
• rustdoc: don't hide inherent implementations by default
• clippy: fix ICE in implicit_return
• clippy: fix invalid syntax in from_iter_instead_of_collect suggestion
• clippy: fix needless_borrow suggestion
• clippy: fix redundant_closure for vec! macro in a closure with arguments
• clippy: don't lint multiple_inherent_impl with generic arguments
• clippy: early return from LintPass registration when collecting metadata
• clippy: adding the default lint level to the metadata collection

Rust Compiler Performance Triage

A somewhat quiet week. Some PRs had performance runs performed on them, but the changes were merged despite this. Also, we still have issues with certain benchmarks being noisy.

Triage done by @rylev. Revision range: 25a277..cdbe2

2 Regressions, 2 Improvements, 1 Mixed 0 of them in rollups

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:

• A new prelude for the 2021 edition (trait-only edition)

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] RFC: 2021 Edition
• [disposition: merge] RFC: Overconstraining and omitting unsafe in impls of unsafe trait methods

Tracking Issues & PRs

• [disposition: merge] rustc: Allow safe #[target_feature] on wasm
• [disposition: merge] Show test type during prints
• [disposition: merge] Tracking Issue for VecDeque binary search functions
• [disposition: merge] Tracking issue for WebAssembly SIMD support
• [disposition: merge] Use try_reserve in Vec's io::Write

New RFCs

• ArrayBuilder struct for safe/efficient dynamic array initialisation
• RFC: I/O Safety
• A Cargo profile option trim-path to sanitise absolute paths

Upcoming Events

Online

• May 27, 2021, London/Remote, UK - Runtime reflection, gRPC at scale, and more
• May 27, 2021, Montréal, QC, CN - Rust MTL: Building a Scrabble AI with the fst crate - Rust Montréal
• June 1, 2021, Dublin, IE - June Remote Meetup - Rust Dublin
• June 1, 2021, Buffalo, NY, US - Buffalo Rust User Group, First Tuesdays - Buffalo Rust Meetup

North America

• June 9, 2021, Atlanta, GA, US - Grab a beer with fellow Rustaceans - Rust Atlanta

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

Ockam

• Architect - Rust Library Design (Remote)

Red Hat

• Senior Software Engineer - Virtualization & Storage (Remote Europe)

Starry

• Rust Software Engineer (Boston, MA, US)

NZXT

• Senior Software Engineer for CAM (Remote)
• Senior Software Engineer for Streaming Software (Remote)

Kollider

• Junior Backend Engineer (Remote)
• Senior Backend Engineer (Remote)
• DevOps Engineer (Remote)

Kraken

• Several Rust Engineering Postions Available

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

Quote of the Week

Ok, you wanted it. Let's go full meta:

This time, there were two crates and one quote, which is not much, but ok. Keep it up, folks!

– llogiq on reddit

Thanks to Patrice Peterson for the suggestion!

Please submit quotes and vote for next week!

This Week in Rust is edited by: nellshamrell, llogiq, and cdmistman.

Discuss on r/rust