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.

Updates from Rust Community

Official

• Welcome James Munns to the Leadership Council

Newsletters

• Cyberpunk UI, Minecraft simulation, and volumetric destruction

Project/Tooling Updates

• Fyrox Game Engine 0.34
• Wasmi's New Execution Engine - Faster Than Ever
• iroh@0.17.0 - Everything is a little better
• venndb@0.5.0 - support multi dimensional filter options to be filtered in group

Observations/Thoughts

• Diesel: Continuous Benchmarking Case Study
• Visions of the future: formal verification in Rust
• Avoiding Over-Reliance on mpsc channels in Rust
• How We Migrated Our Static Analyzer From Java To Rust
• Building Agentic RAG with Rust, Qdrant & OpenAI
• Making a Secure Chat in Rust
• Parsing structured environment variables in Rust
• Types and self-documenting code in Rust
• Iggy.rs — one year of building the message streaming
• When allocating unused memory boosts performance by 2x
• Atomic Polling Intervals for Highly Concurrent Workloads
• Taming Floating-Point Sums
• Send & Mutex - Misconceptions about Send

Rust Walkthroughs

• Build with Naz : Linux io_uring and tokio-uring exploration with Rust
• Getting Started with Loco & SeaORM

Miscellaneous

• Rebuilding Consumer Social In Rust
• Report on variadic generics discussion at RustNL.
• How to use ChatGPT with Rust
• [video] Programming Education: Tailoring Tools and Techniques for Rust (Will Crichton in the RustRover livestream series)

Crate of the Week

This week's crate is pulso, a simple metrics collector for TCP/IP.

Thanks to guapodero for the self-suggestion!

Please submit your suggestions and votes for next week!

Call 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.

• zerocopy - CI cache not including installed Cargo tools?
• zerocopy - Debug GitHub Actions issue
• zerocopy - Cargo doc step jq error

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.

• Rust Argentina June 2024 | Closes 2024-05-31 | Buenos Aires, AR | Event date: 2024-06-04
• EuroRust 2024 | Closes 2024-06-03 | Vienna, Austria & online | Event date: 2024-10-10
• Scientific Computing in Rust 2024 | Closes 2024-06-14 | online | Event date: 2024-07-17 - 2024-07-19
• Rust Ukraine 2024 | Closes 2024-07-06 | Online + Ukraine, Kyiv | Event date: 2024-07-27
• Conf42 Rustlang 2024 | Closes 2024-07-22 | online | Event date: 2024-08-22

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

397 pull requests were merged in the last week

• MIR validation: ensure that downcast projection is followed by field projection
• actually use TAIT instead of emulating it
• allow coercing functions whose signature differs in opaque types in their defining scope into a shared function pointer type
• allow monomorphization time const eval failures if the cause is a type layout issue
• an async closure may implement FnMut/Fn if it has no self-borrows
• detect unused structs which implement private traits
• disallow cast with trailing braced macro in let-else
• don't continue probing for method if in suggestion and autoderef hits ambiguity
• don't do cc detection for synthetic targets
• don't eagerly monomorphize drop for types that are impossible to instantiate
• don't suggest adding the unexpected cfgs to the build-script it-self
• drop region constraints for ambiguous goals
• exit the process a short time after entering our ctrl-c handler
• expand for_loops_over_fallibles lint to lint on fallibles behind references
• f32: use constants instead of reassigning a dummy value as PI
• fail relating constants of different types
• fix OutsideLoop's error suggestion: adding label 'block for if block
• fix unexpected_cfgs lint on std
• fix incorrect suggestion for undeclared hrtb lifetimes in where clauses
• fix parsing of erroneously placed semicolons
• follow-up fixes to report_return_mismatched_types
• force the inner coroutine of an async closure to move if the outer closure is move and FnOnce
• handle ReVar in note_and_explain_region
• make sure that the method resolution matches in note_source_of_type_mismatch_constraint
• move #[do_not_recommend] to the #[diagnostic] namespace
• only allow immutable statics with #[linkage]
• only suppress binop error in favor of semicolon suggestion if we're in an assignment statement
• panic directly in Arguments::new* instead of recursing
• pattern types: Prohibit generic args on const params
• properly deal with missing/placeholder types inside GACs
• relax restrictions on multiple sanitizers
• remove DefId from EarlyParamRegion
• remove proof tree formatting, make em shallow
• rename FrameworkOnlyWindows to RawDylibOnlyWindows
• resolve anon const's parent predicates to direct parent instead of opaque's parent
• stop SRoA'ing DynMetadata in MIR
• support C23's Variadics Without a Named Parameter
• tag more stuff with WG-trait-system-refactor
• turn remaining non-structural-const-in-pattern lints into hard errors
• use Backtrace::force_capture instead of Backtrace::capture in rustc_log
• validate the special layout restriction on DynMetadata
• warn (or error) when Self ctor from outer item is referenced in inner nested item
• wrap Context.ext in AssertUnwindSafe
• interpret: make overflowing binops just normal binops
• miri: add back some tokio features
• miri: bugfix MiriAllocBytes to guarantee different addresses
• miri: completely refactor how we manage blocking and unblocking threads
• perf: Delay the construction of early lint diag structs
• stabilize LazyCell and LazyLock
• stabilize div_duration
• stabilize slice_flatten
• rewrite native thread-local storage
• rewrite TLS on platforms without threads
• simplify key-based thread locals
• add opt-for-size core lib feature flag
• always use the general case char count with optimize_for_size
• add IntoIterator for Box<[T]> + edition 2024-specific lints
• add assert_unsafe_precondition to unchecked_{add,sub,neg,mul,shl,shr} methods
• add a fast-path to Debug ASCII &str
• add manual Sync impl for ReentrantLockGuard
• fix VecDeque::shrink_to UB when handle_alloc_error unwinds
• simplify the unchecked_sh[lr] ub-checks a bit
• less syscalls for the copy_file_range probe
• make clamp inline
• fix c_char on AIX
• panic if PathBuf::set_extension would add a path separator
• codegen_llvm: add support for writing summary bitcode
• codegen_gcc: simd: implement pointer provenance intrinsics
• rust-lld: fallback to rustc's sysroot if there's no path to the linker in the target sysroot
• self-contained linker: retry linking without -fuse-ld=lld on CCs that don't support it
• cargo: add more high level traces
• cargo: fetch specific commits even if the github fast path fails
• cargo: fix: check if rev is full commit sha for github fast path
• cargo: fix: remove symlink dir on Windows
• cargo: improve error description when deserializing partial field struct
• cargo: test: switch from drop to let _ due to nightly rustc change
• cargo: upgrade gix from 0.62 to 0.63
• cargo: use i32 rather than usize as "default integer" in library template
• clippy: significant_drop_in_scrutinee: Trigger lint only if lifetime allows early significant drop
• clippy: add new lint while_float
• clippy: add parentheses to let_and_return's suggestion
• clippy: bug fix: lint numbered_fields message error
• clippy: correctly handle closing parens in missing_backticks doc lint
• clippy: Quick Fix for bare URLs
• clippy: fix unnecessary_to_owned interaction with macro expansion
• clippy: fulfill expectations in check_partial_eq_without_eq
• clippy: fulfill expectations in check_unsafe_derive_deserialize
• clippy: suppress iter_on_empty_collections if the iterator's concrete type is relied upon
• rust-analyzer: add toggle_async_sugar assist code action
• rust-analyzer: allow sysroots to only consist of the source root dir
• rust-analyzer: clear diagnostics only after new ones were received
• rust-analyzer: more callable info
• rust-analyzer: fix data_constructor ignoring generics for struct
• rust-analyzer: fix inconsistent cwd of run and debug command in client
• rust-analyzer: ensure implied bounds from associated types are considered in autocomplete
• rust-analyzer: fix format_args lowering passing incorrect parameters to rustc_parse_format
• rust-analyzer: infer type of async block with tail return expr
• rust-analyzer: resolve extern prelude for local mods in block modules
• rust-analyzer: use correct toolchain channel when generating builtin type doc links
• rust-analyzer: various find path fixes
• rust-analyzer: handle {self} when removing unused imports
• rust-analyzer: implement assist to switch between doc and normal comments

Rust Compiler Performance Triage

A relatively quiet week, with few large changes, the largest driven by further increasing the scope of unsafe precondition checking.

Triage done by @simulacrum. Revision range: 1d0e4afd..a59072ec

2 Regressions, 3 Improvements, 5 Mixed; 3 of them in rollups 51 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

• re-organise the compiler team

Tracking Issues & PRs

Rust

• [disposition: merge] Tracking Issue for Error in core
• [disposition: merge] Make WHERE_CLAUSES_OBJECT_SAFETY a regular object safety violation
• [disposition: merge] Show files produced by --emit foo in json artifact notifications
• [disposition: merge] Do not try to reveal hidden types when trying to prove Freeze in the defining scope
• [disposition: merge] Item bounds can reference self projections and still be object safe
• [disposition: merge] Use a default lifetime of 'static in associated consts
• [disposition: merge] Stabilize custom_code_classes_in_docs feature
• [disposition: merge] Tracking issue for integer_atomics
• [disposition: merge] Constification of BinaryHeap construction

Cargo

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

Language Team

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

Language Reference

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

Unsafe Code Guidelines

• No Unsafe Code Guideline RFCs entered Final Comment Period this week.

New and Updated RFCs

• [new] [RFC] Named macro capture groups
• [new] Change crates.io policy to not offer crate transfer mediation
• [new] Externally implementable traits
• [new] [RFC] On_unimplemented_trait_use
• [new] [RFC] Thread spawn hook (inheriting thread locals)

Upcoming Events

Rusty Events between 2024-05-29 - 2024-06-26 🦀

Virtual

• 2024-05-29 | Virtual | Training 4 Programmers LLC
  • Enums, Structs, and Traits - Essential Building Blocks of Rust Programming
• 2024-05-30 | Virtual + In Person (Barcelona, ES) | Mainmatter & BcnRust
  • Rust for the web, Barcelona 2024
• 2024-05-30 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-06-04 | Virtual | Women in Rust
  • Lunch & Learn: A Creative Thinker's Programming Language
• 2024-06-04 | Virtual (Buffalo, NY) | Buffalo Rust Meetup
  • Buffalo Rust User Group
• 2024-06-05 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2024-06-06 | Virtual | Code Mavens
  • Rust Maven Workshop: Your first contribution to an Open Source Rust project
• 2024-06-06 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-06-09 | Virtual | Code Mavens
  • Rust Maven Workshop: GitHub pages for Rust developers (English)
• 2024-06-11 | Virtual (Dallas, TX, US) | Dallas Rust
  • Second Tuesday
• 2024-06-13 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-06-13 | Virtual (Nürnberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2024-06-16 | Virtual | Code Mavens
  • Workshop: Web development in Rust using Rocket (English)
• 2024-06-18 | Virtual (Washington, DC, US) | Rust DC
  • Mid-month Rustful
• 2024-06-19 | Virtual (Vancouver, BC, CA) | Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-06-20 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-06-25 | Virtual (Dallas, TX, US)| Dallas Rust User Group
  • Last Tuesday

Africa

• 2024-06-01 | Kampala, UG | Rust Circle Kampala
  • Rust Circle Meetup

Europe

• 2024-05-28 - 2024-05-30 | Berlin, DE | Oxidize
  • Oxidize Conf 2024
• 2024-05-30 | Amsterdam, NL | Rust Developers Amsterdam Group
  • Rust Developer Meetup @ Avalor AI
• 2024-05-30 | Barcelona, ES | Mainmatter & BcnRust
  • Rust for the web, Barcelona 2024
• 2024-05-30 | Berlin, DE | Rust Berlin
  • Rust and Tell - Title
• 2024-05-30 | Copenhagen, DK | Copenhagen Rust Community
  • Rust meetup #47 sponsored by Microsoft!
• 2024-05-30 | Oslo, NO | Rust Oslo
  • Rust Hack'n'Learn at Kampen Bistro
• 2024-05-30 | Vienna, AT | Rust Vienna
  • Rust Vienna Meetup - May - Rust Backend 101
• 2024-06-05 | Hamburg, DE | Rust Meetup Hamburg
  • Rust Hack & Learn June 2024
• 2025-06-06 | Vilnius, LT | Rust Vilnius
  • Enjoy our second Rust and ZIG event
• 2024-06-19 - 2024-06-24 | Zürich, CH | RustFest Zürich
  • RustFest Zürich 2024
• 2024-06-20 | Aarhus, DK | Rust Aarhus
  • Talk Night at Trifork

North America

• 2024-05-30 | Mountain View, CA, US | Mountain View Rust Meetup
  • Rust Meetup at Hacker Dojo
• 2024-05-31 | Boston, MA, US | Boston Rust Meetup
  • Boston Common Rust Lunch, May 31
• 2024-06-08 | Somerville, MA, US | Boston Rust Meetup
  • Porter Square Rust Lunch, Jun 8
• 2024-06-13 | Spokane, WA, US | Spokane Rust
  • Monthly Meetup: Topic TBD!
• 2024-06-18 | San Francisco, CA, US | San Francisco Rust Study Group
  • Rust Hacking in Person
• 2024-06-20 | Seattle, WA, US | Seattle Rust User Group
  • Seattle Rust User Group Meetup

Oceania

• 2024-06-25 | Canberra, ACt, AU | Canberra Rust User Group (CRUG)
  • June Meetup

South America

• 2024-06-06 | Buenos Aires, AR | Rust en Español | Rust Argentina
  • Juntada de Junio

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

I’ve said it before and I’ll say it again: as a child of OCaml and C++, Rust currently is the best language for production compiler-shaped things.

– Alex Kladov on lobste.rs

Thanks to Stephan Sokolow 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.

Email list hosting is sponsored by The Rust Foundation

Discuss on r/rust