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.

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Updates from Rust Community

Official

• September Project Goals Update
• WebAssembly targets: change in default target-features

Project/Tooling Updates

• Bevy Foundation is now a 501(c)(3) Public Charity
• Development of rustc_codegen_gcc
• Postcard 2.0: Looking for Sponsors!
• Announcing Stable V8 Bindings for Rust
• Perpetual 0.4.7, Quantile regression support and improved multi-threading
• git-cliff 2.6.0 is released! (a highly customizable changelog generator)
• Fjall 2.0, LSM-based safe Rust key-value storage engine

Observations/Thoughts

• "Truly Hygienic" Let Statements in Rust
• One year of Rust in production
• Rust panics under the hood, and implementing them in .NET
• [video] Miguel Raz - Building a compile-time SIMD optimized smoothing filter
• [video] Rust LLM Frameworks have a Bright Future
• [audio] What Are You Syncing About?
• [audio] You might not need Arc

Rust Walkthroughs

• The Watermelon Operator
• Fast Unorm Conversions
• A small trick for simple Rust/C++ interop
• [video] Decrusting the quickcheck crate
• [video] Build low poly terrain from planes meshes in Bevy
• [video] Build with Naz : Rust lifetimes
• [video] Backend in Rust 02 - JWT Authentication, Sea ORM, Axum, Rust

Miscellaneous

• Eliminating Memory Safety Vulnerabilities at the Source
• Committing to Rust in the kernel
• How to Learn Rust in 2024: A Complete Beginner’s Guide to Mastering Rust Programming

Crate of the Week

This week's crate is perpetual, a self-generalizing gradient boosting implementation.

Thanks to Mutlu Simsek for the self-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.

• This Week in Rust - We are recruiting more editors!

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

400 pull requests were merged in the last week

• add arm64e-apple-tvos target
• parser: recover from ::: to ::
• read_volatile __rust_no_alloc_shim_is_unstable in alloc_zeroed
• add unqualified_local_imports lint
• add recursion limit to FFI safety lint
• apply EarlyOtherwiseBranch to scalar value
• assert that explicit_super_predicates_of and explicit_item_super_predicates truly only contains bounds for the type itself
• bail if there are too many non-region infer vars in the query response
• call module_name_to_str instead of just unwrapping
• change download-ci-llvm default from if-unchanged to true
• check params for unsafety in THIR
• compiler: accept "improper" ctypes in extern "rust-cold" fn
• compiler: factor out OVERFLOWING_LITERALS impl
• correct outdated object size limit
• disallow hidden references to mutable static
• do not ICE with incorrect empty suggestion
• do not expect infer/bound/placeholder/error in v0 symbol mangling
• don't ICE in opaque_hidden_inferred_bound lint for RPITIT in trait with no default method body
• don't call extern_crate when local crate name is the same as a dependency and we have a trait error
• don't call ty::Const::normalize in error reporting
• encode coroutine_by_move_body_def_id in crate metadata
• ensure that keyword_ident lint doesn't trigger on 'r#kw lifetime
• fix break_last_token
• fix anon const def-creation when macros are involved take 2
• fix circular fn_sig queries to correct number of args for methods
• fix fluent diagnostics
• further improve diagnostics for expressions in pattern position
• gate repr(Rust) correctly on non-ADT items
• get rid of niche selection's dependence on fields's order
• handle unsized consts with type str in v0 symbol mangling
• implement Return Type Notation (RTN)'s path form in where clauses
• improve handling of raw-idents in check-cfg
• normalize consts in writeback when GCE is enabled
• relate receiver invariantly in method probe for Mode::Path
• remove semi-nondeterminism of DefPathHash ordering from inliner
• replace calls to ty::Const::{try_}eval in mir build/pattern analysis
• rework non_local_definitions lint to only use a syntactic heuristic
• support 128-bit atomics on s390x
• take more advantage of the isize::MAX limit in Layout
• use Vec in rustc_interface::Config::locale_resources
• win: open dir for sync access in remove_dir_all
• miri: automatically add/remove labels when github review (requests) are used
• miri: refactor fd read/write
• add extern "C-cmse-nonsecure-entry" fn
• don't alloca for unused locals
• perf: skip normalizing param env if it is already normalized
• begin experimental support for pin reborrowing
• RepeatN: use MaybeUninit
• add Thread::{into_raw, from_raw}
• add Vec::as_non_null
• add new_cyclic_in for Rc and Arc
• add str.as_str() for easy Deref to string slices
• avoid re-validating UTF-8 in FromUtf8Error::into_utf8_lossy
• delay uncapping the max_read_size in File::read_to_end
• add Lazy{Cell,Lock}::get[_mut] and force_mut
• make unstable Result::flatten a const fn
• mark char::make_ascii_uppercase and char::make_ascii_lowercase as const
• mark u8::make_ascii_uppercase and u8::make_ascii_lowercase as const
• pass fmt::Arguments by reference to PanicInfo and PanicMessage
• stabilize const MaybeUninit::as_mut_ptr
• remove uneeded PartialOrd bound in cmp::Ord::clamp
• std: implement the random feature (alternative version)
• support char::encode_utf16 in const scenarios
• support char::encode_utf8 in const scenarios
• futures: fix issues with AsyncBufRead::read_line and AsyncBufReadExt::lines
• hashbrown: implement Clone and Debug for HashTable's Iter struct
• hashbrown: implement Debug, FusedIterator and Iterator::fold for all HashTable iterators
• hashbrown: re-introduce a way to get the allocation size of a table
• cargo: complete: Upgrade clap_complete
• cargo: complete: Harden --target completions
• cargo: resolve: Don't list transitive, incompatible dependencies as available
• cargo: resolve: Improve multi-MSRV workspaces
• cargo: add a --dry-run flag to the install command
• cargo: add custom completer for cargo build --example=<TAB>
• cargo: add custom completer for cargo help <TAB>
• cargo: add custom completer for completing benchmark names
• cargo: add custom completer for completing target triple
• cargo: add custom completer for completing test names
• cargo: suggest cargo info command in the cargo search result
• rustdoc: use the correct span for doctests
• clippy: ignore missing_panics_doc in const context
• clippy: fix if_then_some_else_none sugg missing closure intro
• clippy: generate versions HTML directly (nice poem, @xFredNet)
• clippy: initial impl of unnecessary_first_then_check
• clippy: lint comparison to empty slice using PartialEq methods
• clippy: unused trait imports (formerly anonymous trait import)
• clippy: use contiguous spans for empty_line_after_* suggestion
• rust-analyzer: don't lint names of #[no_mangle] extern fns
• rust-analyzer: add diagnostics for unsafe_op_in_unsafe_fn
• rust-analyzer: implement expr_2021
• rust-analyzer: support the ${concat(...)} metavariable expression
• rust-analyzer: always cache macro expansions' root node in Semantics
• rust-analyzer: don't complete ; when in closure return expression
• rust-analyzer: extend type_variable_table when modifying index is larger than the table size
• rust-analyzer: get rid of $crate in expansions shown to the user
• rust-analyzer: handle errors and lints from external macros
• rust-analyzer: handle lint attributes that are under #[cfg_attr]
• rust-analyzer: remove check that text of parse_expr_from_str() matches the produced parsed tree
• rust-analyzer: support expect in attribute completion and hover
• rust-analyzer: when checking for forbidden expr kind matches, account for rawness

Rust Compiler Performance Triage

Not too much happened this week. Most regressions of note were readily justified as removing sources of unpredictable/inconsistent behavior from code-generation. There was one notable improvement, from PR #130561: avoiding redoing a redundant normalization of the param-env ended up improving compile times for 93 primary benchmarks by -1.0% on average.

Triage done by @pnkfelix. Revision range: 170d6cb8..749f80ab Revision range: 506f22b4..4cadeda9

(there are two revision ranges to manually work around a rustc-perf website issue.)

2 Regressions, 2 Improvements, 7 Mixed; 4 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:

• Mergeable rustdoc cross-crate info

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: Allow boolean literals as cfg predicates
• [disposition: merge] Trait method impl restrictions
• [disposition: merge] Supertrait item shadowing v2
• [disposition: merge] Move rustdoc-types crate to T-Rustdoc ownership.

Tracking Issues & PRs

Rust

• [disposition: merge] Tracking Issue for const_ptr_write
• [disposition: merge] Tracking Issue for PanicHookInfo::payload_as_str()
• [disposition: merge] Tracking Issue for const_replace
• [disposition: merge] ptr::add/sub: do not claim equivalence with offset(c as isize)
• [disposition: merge] Allow dropping dyn Trait principal
• [disposition: merge] Stabilize expr_2021 fragment specifier in all editions
• [disposition: merge] Make deprecated_cfg_attr_crate_type_name a hard error
• [disposition: merge] atomics: allow atomic and non-atomic reads to race

Cargo

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

Language Team

• [disposition: merge] Meeting proposal: rename "object safety" to "dyn compatibility"

Language Reference

• No Language Reference RFCs entered Final Comment Period this week.

Unsafe Code Guidelines

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

New and Updated RFCs

• [new] Declarative macro_rules! derive macros
• [new] Declarative macro_rules! attribute macros

Upcoming Events

Rusty Events between 2024-09-25 - 2024-10-23 🦀

Virtual

• 2024-09-25 | Virtual (Cardiff, UK)| Rust and C++ Cardiff
  • Reflections on RustConf 2024
• 2024-09-26 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-09-26 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Rusty secure communication on embedded devices
• 2024-10-02 | Virtual (Cardiff, UK)| Rust and C++ Cardiff
  • Rust for Rustaceans Book Club: Chapter 8 - Asynchronous Programming
• 2024-10-02 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2024-10-02 | Virtual (Vancouver, BC, CA) | Vancouver Postgres
  • Leveraging a PL/RUST extension to protect sensitive data in PostgreSQL
• 2024-10-03 | Virtual | Women in Rust
  • Part 1 of 4 - Rust Essentials: Build Your First API
• 2024-10-03 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-10-08 | Virtual (Dallas, TX, US) | Dallas Rust
  • Second Tuesday
• 2024-10-10 | Virtual | Women in Rust
  • Part 2 of 4 - Navigating Rust Web Frameworks: Axum, Actix, and Rocket
• 2024-10-10 | Virtual (Barcelona, ES) | BcnRust + Codurance
  • 15th BcnRust Meetup
• 2024-10-10 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-10-10 | Virtual (Girona, ES) | Rust Girona
  • Leveraging Rust to Improve Your Programming Fundamentals & De Rust A Solana
• 2024-10-10 - 2024-10-11 | Virtual and In-Person (Vienna, AT) | Euro Rust
  • Euro Rust 2024
• 2024-10-14 | Virtual | Women in Rust
  • 👋 Community Catch Up
• 2024-10-16 | Virtual and In-Person (Vancouver, BC, CA) | Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-10-17 | Virtual | Women in Rust
  • Part 3 of 4 - Hackathon Ideation Lab
• 2024-10-17| Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-10-22 | Virtual (Dallas, TX, US) | Dallas Rust
  • Last Tuesday

Africa

• 2024-10-05 | Kampala, UG | Rust Circle Kampala
  • Rust Circle Meetup

Asia

• 2024-09-30 | Singapore, SG | Singapore Rust Meetup
  • How to use Embassy-rs on Esp32
• 2024-10-09 | Subang Jaya / Kuala Lumpur, Selangor, MY | Rust Malaysia
  • Rust Malaysia Meetup - Traits and How to Read Trait (October 2024)
• 2024-10-17 - 2024-10-18 | Beijing, CN | Global Open-Source Innovation Meetup (GOSIM)
  • GOSIM 2024
• 2024-10-19 | Bangalore/Bengaluru, IN | Rust Bangalore
  • October 2024 Rustacean meetup

Europe

• 2024-09-26 | Aarhus, DK | Rust Aarhus
  • Talk Night at Talk Night at Alexandra Instituttet
• 2024-09-26 | Augsburg, DE | Rust Meetup Augsburg
  • Rust Meetup #9: From loops to folds
• 2024-09-26 | Berlin, DE | OpenTechSchool Berlin + Rust Berlin
  • Rust and Tell - Title
• 2024-09-26 | Prague, CZ | Rust Prague
  • Rust Meetup Prague (September 2024)
• 2024-09-27 | Mannheim, DE | Hackerstolz e.V.
  • Hackerstolz Stammtisch Rhein-Neckar
• 2024-10-02 | Oxford, UK | Oxfrod Rust Meetup Group
  • Rust for Rustaceans Book Club: Chapter 11: Foreign Function Interfaces
• 2024-10-02 | Stockholm, SE | Stockholm Rust
  • Rust Meetup @Funnel
• 2022-10-03 | Nürnberg, DE | Rust Nurnberg DE
  • Rust Nürnberg online
• 2024-10-03 | Oslo, NO | Rust Oslo
  • Rust Hack'n'Learn at Kampen Bistro
• 2024-10-09 | Reading, UK | Reading Rust Workshop
  • Reading Rust Meetup
• 2024-10-10 - 2024-10-11 | Virtual and In-Person (Vienna, AT) | Euro Rust
  • Euro Rust 2024
• 2024-10-15 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
  • Topic TBD

North America

• 2024-09-25 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2024-09-26 | Nashville, TN, US | Music City Rust Developers
  • Music City Rust Develpers : Community Presentations
• 2024-09-27 | Cambridge, MA, US | Boston Rust Meetup
  • Beacon Hill Rust Lunch, Sep 27
• 2024-10-03 | Boston, MA, US | SquiggleConf
  • SquiggleConf 2024: "Oxc: Pluggable Next-Gen Tooling At Rust Speed", Don Isaac
• 2024-10-03 | St. Louis, MO, US | STL Rust
  • Iterators in Rust
• 2024-10-04 | Mexico City, DF, MX | Rust MX
  • Multi threading y Async en Rust pt1. Prerequisitos
• 2024-10-08 | Detroit, MI, US | Detroit Rust
  • Rust Community Meetup - Ann Arbor
• 2024-10-15 | Virtual (Washington, DC, US) | Rust DC
  • Mid-month Rustful
• 2024-10-16 | Virtual and In-Person (Vancouver, BC, CA) | Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-10-17| Virtual and In-Person (Seattle, WA, US) | Seattle Rust User Group
  • October Meetup
• 2024-10-23 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground

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

New users feel like iteration times are so slow and it takes forever to get going with Rust. But if there's a library available, I feel like I'm roughly as productive with Rust as I am with Ruby, if not more, when I think about the whole amount of work I'm doing. I haven't really figured out how to talk about that without sounding purely like a zealot, but yeah, I feel like Rust is actually very, very productive, even though many people don't see it that way initially.

– Steve Klabnik at Oxidize Conference

Thanks to Brian Kung 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