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 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

• Announcing Rustup 1.27.0
• crates.io: Download changes

Newsletters

• This Month in Rust OSDev: February 2024

Project/Tooling Updates

• Bevy Foundation
• Rust Flashcards - 557 cards to learn Rust from first principles
• Lib.rs website improvements
• Sudo-rs dependencies: when less is better
• rust-analyzer changelog #224
• biscotti, a new crate for HTTP cookies
• Boa release v0.18
• Announcing Relm4 0.7 and 0.8
• Meilisearch 1.7 — New OpenAI models & GPU support for Hugging Face embeddings
• Cargo wizard: automate Cargo project configuration
• GreptimeDB v0.7 is ready for cloud-native monitoring
• [video] Project Syn - Simon Gerber - Rust Zürisee March 2024

Observations/Thoughts

• Fast Development In Rust, Part One
• Mental model for unsafe (complete rewrite)
• 10 years in Open Source
• [audio] Season Finale - Rust in Production Podcast
• [video] SemVer in Rust: Breakage, Tooling, and Edge Cases

Rust Walkthroughs

• How to Use Rust Procedural Macros to Replace Panic with syn’s Fold
• Rust Iterators Beyond the Basics - part 1
• Rust Multi-crate project in a monorepo
• Using Stripe Payments with Rust
• Problems around modelling an asynchronous API for database transaction in Rust
• Embedded Rust Bluetooth on ESP: BLE Scanner
• [video] Implementing (parts of) git from scratch in Rust
• [video] The Billion Rows Challenge in Rust - an intro to Rust for data engineering

Miscellaneous

• Rust impact on engineering management
• From medical doctor to rust developer
• February 2024 Rust Jobs Report

Crate of the Week

This week's crate is biscotti, an opinionated library to deal with HTTP cookies on the server side.

We saw a lamentable lack of suggestions this week. Nevertheless, llogiq is pleased with his selection.

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:

• Tracking Issue for min_exhaustive_patterns
  • Testing Steps

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.

• Hyperswitch - [REFACTOR]: Remove Default Case Handling - Bambora
• Hyperswitch - [REFACTOR]: Remove Default Case Handling - Mollie
• Hyperswitch - [REFACTOR]: Remove Default Case Handling - Braintree
• GreptimeDB - Painless integrating with Grafana via Prometheus plugin
• GreptimeDB - Add strict mode to validate protocol strings
• Fluvio - fvm switch fails on some systems with running local cluster
• Fluvio - Add new command fluvio cluster resume
• quinn - Add CI for mobile platforms (iOS & Android)

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

CFP - Speakers

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. They are ordered below by when the CFP closes.

• RustFest Zürich 2024 | Closes 2024-03-31 | Zürich, Switzerland | Event date: 2024-06-19 - 2024-06-24
• Oxidize 2024 | Closes 2024-03-24 | Berlin, Germany | Event date: 2024-05-28 - 2024-05-30
• RustConf 2024 | Closes 2024-04-25 | Montreal, Canada | Event date: 2024-09-10
• EuroRust 2024| Closes 2024-06-03 | Vienna, Austria & online | Event on 2024-10-10
• Scientific Computing in Rust 2024| Closes 2024-06-14 | online | Event date: 2024-07-17 - 2024-07-19

If you are an event organizer hoping to expand the reach of your event, please submit a link to the submission website through a PR to TWiR.

Updates from the Rust Project

506 pull requests were merged in the last week

• add new Tier-3 target: loongarch64-unknown-linux-musl
• add arm64ec-pc-windows-msvc target
• LLVM Bitcode Linker: A self contained linker for nvptx and other targets
• AST validation: Improve handling of inherent impls nested within functions and anon consts
• const_eval_select: make it safe but be careful with what we expose on stable for now
• hir_analysis: enums return None in find_field
• add a description field to target definitions
• add an option to have an external download/bootstrap cache
• add asm goto support to asm!
• add metadata to targets
• add proper cfgs for struct HirIdValidator used only with debug-assert
• add the new description field to Target::to_json, and add descriptions for some MSVC targets
• allow codegen backends to opt-out of parallel codegen
• allow multiple impl Into<{D,Subd}iagMessage> parameters in a function
• allow targets to override default codegen backend
• apply EarlyBinder only to TraitRef in ImplTraitHeader
• avoid invoking the intrinsic query for DefKinds other than Fn or AssocFn
• avoid overlapping privacy suggestion for single nested imports
• change some attributes to only_local
• check that return type is WF in typeck
• detect unused struct impls pub trait
• diagnostics: do not suggest using #[unix_sigpipe] without a value
• distinguish between library and lang UB in assert_unsafe_precondition
• do not try to format removed files
• don't ICE if we collect no RPITITs unless there are no unification errors
• don't ICE in CTFE if raw/fn-ptr types differ
• don't pass a break scope to Builder::break_for_else
• don't require specifying unrelated assoc types when trait alias is in dyn type
• dynamically size sigaltstk in std
• errors: share SilentEmitter between rustc and rustfmt
• fix crash in internal late lint checking
• fix legacy numeric constant diag items
• fix linting paths with qself in unused_qualifications
• fix metadata for dyn-star in new solver
• fix misaligned loads when loading UEFI arg pointers
• fix redundant import errors for preload extern crate
• fix type resolution of associated const equality bounds (take 2)
• fix: localWaker memory leak and some stability attributes
• implement async closure signature deduction
• improve diagnostics for parenthesized type arguments
• interpret: do not call machine read hooks during validation
• limit the number of names and values in check-cfg diagnostics
• lint singleton gaps after exclusive ranges
• loongarch: add frecipe and relax target feature
• lower transmutes from int to pointer type as gep on null
• make TAITs and ATPITs capture late-bound lifetimes in scope
• make DefiningAnchor::Bind only store the opaque types that may be constrained, instead of the current infcx root item
• make std::os::unix::ucred module private
• make not finding core a fatal error
• make the lowering of thir::ExprKind::If easier to follow
• match lowering: define a convenient struct
• only compare ambiguity item that have hard error
• only set noalias on Box with the global allocator
• record mtime in bootstrap's LLVM linker script
• refactor pre-getopts command line argument handling
• refer to "slice" instead of "vector" in Ord and PartialOrd trait impl of slices
• remove feed_local_def_id
• removing absolute path in proc-macro
• rework untranslatable_diagnostic lint
• run a single huge par_body_owners instead of many small ones after each other
• silence mismatched types errors for implied projections
• stabilize the #[diagnostic] namespace and #[diagnostic::on_unimplemented] attribute
• std support for wasm32 panic=unwind
• store backtrace for must_produce_diag
• temporarily make allow-by-default the non_local_definitions lint
• tweak the way we protect in-place function arguments in interpreters
• uplift some feeding out of associated_type_for_impl_trait_in_impl and into queries
• use GEP inbounds for ZST and DST field offsets
• use ptradd for vtable indexing
• MIR printing: print the path of uneval'd const
• miri: do not apply aliasing restrictions to Box with custom allocator
• miri: remove the ability to disable ABI checking
• perf: build rustc with 1CGU on x86_64-apple-darwin and x86_64-pc-windows-msvc
• replace the default branch with an unreachable branch If it is the last variant
• optimize write with as_const_str for shorter code
• fix quadratic behavior of repeated vectored writes
• net: don't use checked arithmetic when parsing numbers with known max digits
• align_offset, align_to: no longer allow implementations to spuriously fail to align
• impl From<TryReserveError> for io::Error
• make impl<Fd: AsFd> impl take ?Sized
• add Read impl for &Stdin
• std::rand: enable getrandom for dragonflybsd too
• std::threads: revisit stack address calculation on netbsd
• win10: use GetSystemTimePreciseAsFileTime directly
• windows: implement condvar, mutex and rwlock using futex
• add slice::try_range
• implement MaybeUninit::fill{,_with,_from}
• RawVec::into_box: avoid unnecessary intermediate reference
• Vec::try_with_capacity
• add #[inline] to BTreeMap::new constructor
• add std::ffi::c_str module
• futures: add a helper for always ready futures
• cargo: cli: allow logging to chrome traces
• cargo: doc: collapse down generated statuses without --verbose
• cargo: log: trace parameters to align with profile
• cargo: lockfile: make diffing/printing more reusable
• cargo: consistently compare MSRVs
• rustfmt: fix failure with => in comment after match =>
• clippy: new lints: duplicated_attributes, manual_unwrap_or_default, nonminimal_bool, zero_repeat_side_effects and const_is_empty
• clippy: fix duplicate diagnostics in manual_retain, mut_mut, no_effect_replace and single_match
• clippy: don't lint redundant_field_names across macro boundaries
• clippy: fix std_instead_of_core false positive
• clippy: fix missing_docs_in_private_items on some proc macros
• clippy: have more lints respect #[allow] on exprs
• rust-analyzer: add QuickFix for unresolved field
• rust-analyzer: add fix for unused_variables
• rust-analyzer: add proc macro semantic token type
• rust-analyzer: add config and capability for test explorer
• rust-analyzer: don't escape \ and $ in "Extract format expressions" assist
• rust-analyzer: don't force draw a dependency edge to the real_span_map query
• rust-analyzer: don't invalid body query results when generating desugared names
• rust-analyzer: fix method resolution snapshotting receiver_ty too early
• rust-analyzer: function argument type inference with associated type impl trait
• rust-analyzer: keep attributes in assist 'generate_delegate_trait'
• rust-analyzer: panic when using float numbers without dots in chain calls
• rust-analyzer: preserve $ and \ in postfix format completions
• rust-analyzer: remove accidental dependency between parse_macro_expansion and parse
• rust-analyzer: skip match diagnostics for partially unknown types
• rust-analyzer: for toolchain binaries use the full path found in $PATH
• rust-analyzer: stop eagerly resolving inlay hint text edits for VSCode

Rust Compiler Performance Triage

A mixed week, with a vast number of improvements (in large part due to PR

122010, which undoes a prior regression; PR #120985, a host LLVM update).

But also three admittedly small-ish regressions which seemed unanticipated and were still large enough that I did not feel comfortable rubber-stamping them with a perf-regression-triaged marking.

Triage done by @pnkfelix. Revision range: 41d97c8a..e919669d

2 Regressions, 5 Improvements, 9 Mixed; 5 of them in rollups 54 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:

• RFC: Packages as (optional) namespaces

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

• No RFCs entered Final Comment Period this week.

Tracking Issues & PRs

Rust

• [disposition: merge] Normalize trait ref before orphan check & consider ty params in alias types to be uncovered
• [disposition: merge] Split refining_impl_trait lint into _reachable, _internal variants
• [disposition: merge] debuginfo: Stabilize -Z debug-macros, -Z collapse-macro-debuginfo and #[collapse_debuginfo]
• [disposition: merge] Stabilize associated type bounds (RFC 2289)
• [disposition: merge] c_unwind full stabilization request: change in extern "C" behavior
• [disposition: postpone] Consider linting against 00B7 aka interpunct aka middle dot
• [disposition: merge] Prevent opaque types being instantiated twice with different regions within the same function
• [disposition: merge] instantiate higher ranked goals outside of candidate selection
• [disposition: merge] Add wasm_c_abi future-incompat lint
• [disposition: merge] stabilize ptr.is_aligned, move ptr.is_aligned_to to a new feature gate
• [disposition: merge] feat: implement {Div,Rem}Assign<NonZero<X>> on X

Cargo

• [disposition: merge] cargo: prevent dashes in lib.name

New and Updated RFCs

• [new] Make cargo install respect lockfiles by default

Upcoming Events

Rusty Events between 2024-03-13 - 2024-04-10 🦀

Virtual

• 2024-03-14 | Virtual (Berlin, DE) | OpenTechSchool Berlin
  • Web Frontend Co-Learning (online)
• 2024-03-14 | Virtual (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup | Mirror: Berline.rs page
• 2024-03-14 | Virtual (Nürnberg, DE) | Rust Nüremberg
  • Rust Nürnberg online
• 2024-03-14 | Virtual (San Diego, CA, US) | San Diego Rust
  • San Diego Rust March 2024 Tele-Meetup
• 2024-03-19 | Virtual | Formal Land
  • Rust for Lunch: Formal verification for Rust with coq-of-rust. Speaker: Guillaume Claret | Docs
• 2024-03-19 | Virtual (Washinigton, DC, US) | Rust DC
  • Mid-month Rustful
• 2024-03-20 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
  • Rust for Rustaceans Book Club: Chapter 3 - Designing Interfaces
• 2024-03-20 | Virtual (Vancouver, BC, CA)| Vancouver Rust
  • Rust Study/Hack/Hang-out
• 2024-03-21 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-03-26 | Virtual + In Person (Barcelona, ES) | BcnRust
  • 13th BcnRust Meetup - Stream
• 2024-03-26 | Virtual (Dallas, TX, US) | Dallas Rust
  • Last Tuesday
• 2024-03-28 | Virtual + In Person (Berlin, DE) | OpenTechSchool Berlin + Rust Berlin
  • Rust Hack and Learn | Mirror: Rust Hack n Learn Meetup
• 2024-04-02 | Virtual (Buffalo, NY, US) | Buffalo Rust
  • Buffalo Rust User Group
• 2024-04-03 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
  • Rust for Rustaceans Book Club: Chapter 4 - Error Handling
• 2024-04-03 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2024-04-09 | Virtual (Dallas, TX, US) | Dallas Rust
  • Second Tuesday

Africa

• 2024-04-05 | Kampala, UG | Rust Circle Kampala
  • Rust Circle Meetup

Asia

• 2024-03-30 | New Delhi, IN | Rust Delhi
  • Rust Delhi Meetup #6

Europe

• 2024-03-13 | Paris, FR | Paris Rustaceans
  • Rust Meetup in Paris
• 2024-03-14 | Reading, UK | Reading Rust Workshop
  • Reading Rust Meetup at Browns
• 2024-03-19 | Aarhus, DK | Rust Aarhus
  • Hack Night
• 2024-03-19 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
  • Rust Interactive Session
• 2024-03-19 | Prague, CZ | Rust Prague
  • Rust Meetup @ Charles University
• 2024-03-20 | Girona, ES | Rust Girona
  • Introduction to programming Microcontrollers with Rust
• 2024-03-20 | Lyon, FR | Rust Lyon
  • Rust Lyon Meetup #9
• 2024-03-21 | Augsburg, DE | Rust Meetup Augsburg
  • Augsburg Rust Meetup #6
• 2024-03-21 | Lille, FR | Rust Lille
  • Rust Lille #6: Du RSS et de L'ECS !
• 2024-03-21 | Vienna, AT | Rust Vienna
  • Rust Vienna Meetup - March - Unsafe Rust
• 2024-03-23 | Stockholm, SE | Ferris' Fika Forum
  • Ferris' Fika Forum | Map
• 2024-03-26 | Barcelona, ES + Virtual | BcnRust
  • 13th BcnRust Meetup
• 2024-03-26 - 2024-03-28 | London, UK | Rust Nation UK
  • Rust Nation 2024 - Conference
• 2024-03-28 | Berlin, DE | Rust Berlin
  • Rust and Tell
• 2024-04-10 | Cambridge, UK | Cambridge Rust Meetup
  • Rust Meetup Reboot 3
• 2024-04-10 | Oslo, NO | Rust Oslo
  • Rust Hack'n'Learn at Kampen Bistro

North America

• 2024-03-13 | Boston, MA, US | Boston Rust Meetup
  • Northeastern Rust Lunch
• 2024-03-19 | San Francisco, CA, US | San Francisco Rust Study Group
  • Rust Hacking in Person
• 2024-03-21 | Seattle, WA, US | Seattle Rust User Group
  • Seattle Rust User Group Meetup
• 2024-03-22 | Somerville, MA, US | Boston Rust Meetup
  • Somerville Union Square Rust Lunch, Mar 22
• 2024-03-26 | Minneapolis, MN, US | Minneapolis Rust Meetup
  • Minneapolis Rust: Getting started with Rust!
• 2024-03-27 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2024-03-27 | Hawthorne, CA, US | Freeform
  • Rust in the Physical World 🦀 Tech Talk Event at Freeform
• 2024-03-31 | Boston, MA, US | Boston Rust Meetup
  • Beacon Hill Rust Lunch, Mar 31

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 10 years we went from “Rust will never replace C and C++” to “New C/C++ should not be written anymore, and you should use Rust”. Good job.

– dpc_pw on lobste.rs

Thanks to Dennis Luxen 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