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 X(formerly 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 and archives can be viewed at this-week-in-rust.org. If you find any errors in this week's issue, please submit a PR.

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Updates from Rust Community

Newsletters

• Bevy 0.14's Release, Cosmic Text, and water reflections

Project/Tooling Updates

• Maelstrom v0.10.0: A Hermetic, Fast, Clustered Test Runner: Added Support for Python Tests, Other Container Image Repositores, and more
• Rust for filesystems
• Bevy 0.14
• Introducing Avian Physics 0.1
• iroh 0.20.0
• Release Nutype 0.4.3
• Rerun 0.17 - better blueprints with defaults and overrides for any data

Observations/Thoughts

• Rustic Witcher: Reimagining data anonymization
• Memory Safety in C++ vs Rust vs Zig
• Using unsafe in our Rust interpreters: easy, debatably ethical performance
• How to configure CPU cores to be used in a Tokio application with core_affinity
• Further simplifying self-referential types for Rust
• Network Manager and Rust's zbus
• PyO3: From Python to Rust and Back Again
• Properly Testing Concurrent Data Structures
• A Unified Typesystem

Rust Walkthroughs

• Writing Production Rust Macros with macro_rules!
• Mix in Rust
• Demystifying Rust's HTTP ecosystem: Here is how the different crates fit together
• Build with Naz : Rust async in practice tokio::select! & cancellation safety

Miscellaneous

• June 2024 Rust Jobs Report
• [video] Jan Hohenheim discusses Rust, Rust GameDev Newsletter & The Bevy Engine

Crate of the Week

This week's crate is derive_deftly, a proc macro to create derive macros from declarative code.

Thanks to duelafn for the suggestion!

Please submit your suggestions and votes for next week!

Calls 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:

RFCs

• No calls for testing were issued this week.

Rust

• No calls for testing were issued this week.

Rustup

• No calls for testing were issued 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.

Call for Participation; projects and speakers

CFP - Projects

Always wanted to contribute to open-source projects but did not 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 or through a PR to TWiR or by reaching out on X (Formerly twitter) or Mastodon!

CFP - Events

Are you a new or experienced speaker looking for a place to share something cool? This section highlights events that are being planned and are accepting submissions to join their event as a speaker.

If you are an event organizer hoping to expand the reach of your event, please submit a link to the website through a PR to TWiR or by reaching out on X (Formerly twitter) or Mastodon!

Updates from the Rust Project

469 pull requests were merged in the last week

• wasm64 build with target-feature=+simd128,+atomics
• macro_metavar_expr_concat Add support for literals
• out_of_scope_macro_calls: Detect calls inside attributes more precisely
• actually report normalization-based type errors correctly for alias-relate obligations in new solver
• add as_lang_item to LanguageItems, new trait solver
• change asm-comments to verbose-asm, always emit user comments
• change return-type-notation to use (..)
• check alias args for WF even if they have escaping bound vars
• coverage: extract hole spans from HIR instead of MIR
• coverage: rename mir::coverage::BranchInfo to CoverageInfoHi
• disable dead variant removal for #[repr(C)] enums
• emit a wrap expr span_bug only if context is not tainted
• fix FnMut::call_mut/Fn::call shim for async closures that capture references
• fix import suggestion error when path segment failed not from starting
• fix incorrect suggestion for extra argument with a type error
• fix intrinsic const parameter counting with effects
• improve dead code analysis
• improve well known value check-cfg diagnostic for the standard library
• infer async closure signature from (old-style) two-part Fn + Future bounds
• linker: link dylib crates by path
• make FloatTy checks exhaustive in pretty print
• make NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE a deny-by-default lint in edition 2024
• make can_eq process obligations (almost) everywhere
• make push_outlives_components into a TypeVisitor
• make casts of pointers to trait objects stricter
• match ergonomics 2024: Implement TC's match ergonomics proposal
• match ergonomics 2024: align with RFC again
• parenthesize break values containing leading label
• re-implement a type-size based limit
• remove a use of StructuredDiag, which is incompatible with automatic error tainting and error translations
• remove global error count checks from typeck
• rewrite handling of universe-leaking placeholder regions into outlives constraints
• rustdoc-json: better representation of lifetime bounds in where clauses
• rustdoc-search: stop constructing pointless arrays in decode
• show fnsig's unit output explicitly when there is output diff in diagnostics
• stop using specialization in rustc_index and rustc_borrowck
• tweak -1 as usize suggestion
• use ControlFlow results for visitors that are only looking for a single value
• use IndexVec for coroutine local mapping
• use field ident spans directly instead of the full field span in diagnostics on local fields
• use the aligned size for alloca at args/ret when the pass mode is cast
• tweak some structured suggestions to be more verbose and accurate
• use verbose style for argument removal suggestion
• use verbose suggestion for ptr::null_mut()
• use verbose suggestion for changing arg type
• verify that allocations output by GVN are sufficiently aligned
• support tail calls in mir via TerminatorKind::TailCall
• use the native unwind function in miri where possible
• miri function identity hack: account for possible inlining
• miri: TB: refine protector end semantics
• miri: add syscall dup() for unix target
• miri: implement libc::sched_setaffinity on linux
• miri: implement the _mm256_zeroupper and _mm256_zeroall intrinsics
• miri: stacked Borrows: fix PartialEq for Stack
• miri: use the symbol_name query instead of trying to infer from the link_name attribute
• cache hir_owner_nodes in ParentHirIterator
• cache type sizes in type-size limit visitor
• make jump threading state sparse
• stabilize atomic_bool_fetch_not
• stabilize hint::assert_unchecked
• add new_range_api for RFC #3550
• impl PathBuf::add_extension and Path::with_added_extension
• improve std::Path's Hash quality by avoiding prefix collisions
• specialize TrustedLen for Iterator::unzip()
• linkedList's Cursor: method to get a ref to the cursor's list
• mark format! with must_use hint
• optimize SipHash by reordering compress instructions
• cargo: add rustdocflags to Unit's Debug impl
• cargo: allow enabling config-include feature in config
• cargo: dont make new constant InternedString in hot path
• cargo: fix compatible_with_older_cargo test
• cargo: fix: improve message for inactive weak optional feature with edition2024 through unused dep collection
• cargo: pass rustflags to artifacts built with implicit targets when using target-applies-to-host
• bindgen: fix generated constants: f64::INFINITY & f64::NEG_INFINITY
• jsondocck: add $FILE built-in variable
• jsondocck: use correct index for error message
• clippy: almost_complete_range: Delay suggestion creation
• clippy: doc_markdown: detect escaped when checking unmatched
• clippy: missing_const_for_fn: fix FP when arg ty is impl trait alias ty
• clippy: missing_const_for_fn: fix suggestions for fn with abi that requires const_extern_fn feature
• clippy: needless_return: Support #[expect] on the return statement
• clippy: significant_drop_in_scrutinee: Trigger lint also for scrutinees in while let and if let
• clippy: unnecessary_to_owned: catch to_owned on byte slice to create temporary &str
• clippy: add new lint hashset_insert_after_contains
• clippy: add new lint for byte char slices
• clippy: add cfg_not_test lint
• clippy: fix false positive with into_iter_without_iter
• clippy: fix some false-positive cases of explicit_auto_deref
• clippy: honor avoid-breaking-exported-api in needless_pass_by_ref_mut
• clippy: only check for automatically_derived on impl blocks
• clippy: refactor disallowed_methods and narrow span
• clippy: rework init_numbered_fields
• rust-analyzer: add --keep-going to the check command
• rust-analyzer: add an option to use "::" for the external crate prefix
• rust-analyzer: also mark InferenceResult::has_errors flag when there are error types
• rust-analyzer: disallow nested impl traits
• rust-analyzer: don't emit semantic diagnostics in files with a lot of syntax errors
• rust-analyzer: fix callHierarchy LSP violation
• rust-analyzer: fix double rounding of f32 literals
• rust-analyzer: fix lifetime parameters moving parameter defaults
• rust-analyzer: fix parameter completions using macro expanded source ranges
• rust-analyzer: fix passing message-format after -- in debugging
• rust-analyzer: fix runnables being incorrectly constructed
• rust-analyzer: fix up the syntax tree for macro 2.0
• rust-analyzer: skip match exhaustiveness checking if pattern type contains errors
• rust-analyzer: move lifetimes in front of type and const params but after self
• rust-analyzer: remove version check before using --keep-going

Rust Compiler Performance Triage

More regressions than improvements this week, caused by a combination of fixes, refactorings, third-party dependency updates and in general the compiler doing slightly more work.

Triage done by @kobzol. Revision range: cf2df68d..a2d58197

Summary:

1 Regression, 2 Improvements, 7 Mixed; 3 of them in rollups 62 artifact comparisons made in total

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: * 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] repr(discriminant = ...) for type aliases
• [disposition: merge] Match ergonomics 2024

Tracking Issues & PRs

Rust

• [disposition: merge] Tracking Issue for Missing BMI1, AVX2, SSE2, SSE4.1, SSE4a and TBM intrinsics
• [disposition: merge] offset_from: always allow pointers to point to the same address
• [disposition: merge] Fix ambiguous cases of multiple & in elided self lifetimes
• [disposition: merge] Tracking issue for RFC 2351, "Add is_sorted to the standard library"
• [disposition: merge] Tracking issue for io_slice_advance
• [disposition: merge] Tracking Issue for const_waker

Cargo

• No Cargo Tracking Issues or PRs entered Final Comment Period this week.

Language Team

• No Language Team Tracking Issues or PRs entered Final Comment Period this week.

Language Reference

• [disposition: (unspecified)] elaborate on slice wide pointer metadata

Unsafe Code Guidelines

• No Unsafe Code Guideline Tracking Issues or PRs entered Final Comment Period this week.

New and Updated RFCs

• [new] Promote aarch64-apple-darwin to Tier 1

Upcoming Events

Rusty Events between 2024-07-10 - 2024-08-07 🦀

Virtual

• 2024-07-10 | Virtual | Centre for eResearch
  • Research Computing With The Rust Programming Language
• 2024-07-11 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-07-11 | Hybrid - Virtual and In-person (Mexico City, DF, MX) | Rust MX
  • Programación de sistemas con Rust
• 2024-07-11 | Virtual (Nürnberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2024-07-11 | Virtual (Tel Aviv, IL) | Code Mavens
  • Reading JSON files in Rust (English)
• 2024-07-11 | Virtual (IL) | Rust in Israel
  • Getting started with Rust (Virtual) - מבוא לתכנות ראסט - בזום
• 2024-07-17 | Hybrid - Virtual and In-person (Vancouver, BC, CA) | Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-07-18 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-07-23 | Hybrid - Virtual and In-Person (München/Munich, DE) | Rust Munich
  • Rust Munich 2024 / 2 - hybrid
• 2024-07-24 | Virtual | Women in Rust
  • Lunch & Learn: Exploring Rust API Use Cases
• 2024-07-25 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-07-27 | Hybrid - Virtual and In-Person (Kyiv, UA) | UA Rust
  • UARust Conference 2024
• 2024-07-27 | Virtual | Leptos Monthly Meetup
  • Leptos Monthly Meetup: Pavex with Luca Palmieri
• 2024-07-30 | Virtual (Dallas, TX, US) | Dallas Rust
  • Last Tuesday
• 2024-07-31 | Virtual (Tel Aviv, IL) | Code Mavens
  • Command Line Tools: Implementing wc in Rust (English)
• 2024-08-01 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-08-06 | Virtual | Women in Rust
  • Lunch & Learn! (Virtual)
• 2024-08-06 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
  • Buffalo Rust User Group
• 2024-08-06 | Virtual (Tel Aviv, IL) | Code Mavens
  • Web development in Rust using Rocket - part 2 (English)
• 2024-08-07 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing

Africa

• 2024-08-02 | Kampala, UG | Rust Circle Kampala
  • Rust Circle Meetup

Asia

• 2024-07-20 | Bangalore/Bengaluru, IN | Rust Bangalore
  • July 2024 Rustacean meetup 🤝 C4GT

Europe

• 2024-07-10 | Reading, UK | Reading Rust Workshop
  • Reading Rust Meetup - July
• 2024-07-11 | Prague, CZ | Rust Prague
  • Rust Meetup Prague (July 2024)
• 2024-07-16 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
  • Building a REST API in Rust using Axum, SQLx and SQLite
• 2024-07-16 | Mannheim, DE | Hackschool - Rhein-Neckar
  • Nix Your Bugs & Rust Your Engines #4
• 2024-07-18 | Bern, CH | Rust Bern
  • Rust Bern Meetup #3 2024
• 2024-07-23 | Hybrid - Virtual and In-Person (München/Munich, DE) | Rust Munich
  • Rust Munich 2024 / 2 - hybrid
• 2024-07-25 | Augsburg, DE | Rust Meetup Augsburg
  • Augsburg Rust Meetup #8
• 2024-07-25 | Berlin, DE | OpenTechSchool Berlin + Rust Berlin
  • Rust and Tell - Title
• 2024-07-27 | Hybrid - Virtual and In-Person (Kyiv, UA) | UA Rust
  • UARust Conference 2024
• 2024-07-30 | Basel, CH | Rust Basel
  • Rust Meetup #9

North America

• 2024-07-11 | Hybrid - Mexico City, DF, MX | Rust MX
  • Programación de sistemas con Rust
• 2024-07-11 | Mountain View, CA, US | Mountain View Rust Meetup
  • Rust Meetup at Hacker Dojo
• 2024-07-13 | Cambridge, MA, US | Boston Rust Meetup
  • Lechmere Rust Lunch, July 13
• 2024-07-17 | Hybrid - Vancouver, BC, CA | Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-07-18 | Nashville, TN, US | Music City Rust Developers
  • Music City Rust Developers : holding pattern
• 2024-07-18 | Seattle, WA, US | Seattle Rust User Group
  • Seattle Rust User Group Meetup
• 2024-07-21 | Boston, MA, US | Boston Rust Meetup
  • Back Bay Rust Lunch, July 21
• 2024-07-24 | Austin, TX, US | Rust ATC
  • Rust Lunch - Fareground
• 2024-07-25 | Mountain View, CA, US | Mountain View Rust Meetup
  • Rust Meetup at Hacker Dojo
• 2024-07-29 | Cambridge, MA, US| Boston Rust Meetup
  • Alewife Rust Lunch, July 29

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.

Jobs

Please see the latest Who's Hiring thread on r/rust

Quote of the Week

In Rust, the preferred solution is to avoid the need for such document to exist.

– Kornel on rust-users replying to a question about Rust code guidelines

Thanks to Chayim Refael Friedman for the suggestion!

Please submit quotes and vote for next week!

This Week in Rust is edited by: nellshamrell, llogiq, cdmistman, ericseppanen, extrawurst, andrewpollack, U007D, kolharsam, joelmarcey, mariannegoldin, bennyvasquez.

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Discuss on r/rust