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. If you find any errors in this week's issue, please submit a PR.

Updates from Rust Community

Project/Tooling Updates

• Solving the "floating point precision" problem with... floats?
• Sniffnet v1.2.0
• Bevy + WebGPU
• rust-analyzer changelog #182
• Update-informer v1.0.0
• Pavex, a new Rust web framework - #4: Performance is a feature
• Opensourcing Whichlang, a fast language detection library for Rust

Observations/Thoughts

• How Much Memory Do You Need to Run 1 Million Concurrent Tasks?
• Open sourcing our Rust crate audits
• Rust & Nix: Parallels in Complexity Management
• [audio] PyO3 with David Hewitt

Rust Walkthroughs

• The magic of scope guards
• Mocking in Rust: Mockall and alternatives - LogRocket Blog
• Compress-a-Palooza: Unpacking 5 Billion Varints in only 4 Billion CPU Cycles
• Resilient LL Parsing Tutorial
• ESP32 Embedded Rust at the HAL: Timer Ultrasonic Distance Measurement
• A guide to closures in Rust
• Guide to parsing with nom
• [video] N-Queens Puzzle (PART 2) - Rust - Codurance Screenkata

Research

• [video] Nico Lehmann, Flux: Liquid Types for Rust

Miscellaneous

• RustConf 2023 Schedule

Crate of the Week

This week's crate is whichlang, a fast no-dependencies OSS natural language detector.

Thanks to Brian Kung for the suggestion!

Please submit your suggestions and votes for next week!

Call for Participation

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.

• bilge - Allow others to define their own -Bits derives
• Hyperswitch - Implement CardsInfoInterface for MockDb
• Hyperswitch - Implement DisputeInterface for MockDb
• Hyperswitch - Unite payment intent and setup intent in stripe compatibility

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

Updates from the Rust Project

314 pull requests were merged in the last week

• CFI: fix encode_ty: unexpected Param(B/#1)
• diagnostic: wrap parens for ref impl trait param
• resolve: only disambiguate binding key during define
• add --remote-time flag to curl for bootstrap
• add a conversion from &mut T to &mut UnsafeCell<T>
• add creation time support to FileTimes on apple and windows
• add derive for core::marker::ConstParamTy
• always fall back to PartialEq when a constant in a pattern is not recursively structural-eq
• better diagnostic for use Self::..
• debug format Const's less verbosely
• do not recover when parsing stmt in cfg-eval
• don't expect normalization to succeed in elaborate_drops
• don't inline functions with unsized args
• don't skip inference for type in offset_of!
• don't use inner macro in marker_impls
• dont check must_use on nested impl Future from fn
• erase ReError properly
• erase regions of type in offset_of!
• exclude inherent projections from some alias type matches
• fix dependency tracking for debugger visualizers
• fix doc comment for ConstParamTy derive
• fix duplicate arcinner_layout_for_value_layout calls when using the uninit Arc constructors
• fix local libs not included when printing native static libs
• fix overflow in error emitter
• fix recursion depth handling after confirmation
• fix: emit error when fragment is MethodReceiverExpr and items is empty
• get current target config from --print=cfg
• give a more useful location for where a span_bug was delayed
• give better error when collecting into &[T]
• handle error body in generator layout
• improve cgu merging debug output
• keep only the trait when emitting the error for MyTrait + 'a
• merge return place with other locals in CopyProp
• merge some query impl modules into one
• move rustc_middle/src/ty/query.rs to rustc_middle/src/query/plumbing.rs
• only depend on CFG_VERSION in rustc_interface
• optimize next_chunk impls for Filter and FilterMap
• process current bucket instead of parent's bucket when starting loop for dominators
• recover impl<T ?Sized> correctly
• rename {drop,forget}_{copy,ref} lints to more consistent naming
• replace QueryStruct with arrays local to rustc_query_impl
• shorten backtraces for queries in ICEs
• shorten even more panic temporary lifetimes
• specialize ToString implementation for fmt::Arguments
• specialize query execution for incremental and non-incremental
• support PGO on custom project
• support RISC-V unaligned-scalar-mem target feature
• suppress "erroneous constant used" for constants tainted by errors
• use error term in projection if missing associated item in new solver
• add the weak-intrinsics feature
• stabilize feature cstr_is_empty
• stabilize feature nonzero_negation_ops
• constify slice_as_chunks (unstable)
• use code with reliable branchless code-gen for slice::sort merge
• ascii::Char-ify the escaping code in core
• hashbrown: add NEON backend for RawTable
• hashbrown: add support for allocator-api2
• regex syntax: fix overflow for big counted repetitions
• cargo: lints feature
• cargo: pass -C debuginfo after weakening if explicitly set
• rustdoc: hide repr attribute from doc of types without guaranteed repr
• rustdoc: include strikethrough in item summary
• rustdoc: Only keep impl blocks from bodies
• clippy: add minimal_cfg_condition lint
• clippy: SpanlessEq improvements
• clippy: match_wild_err_arm: do not lint in const contexts
• clippy: redundant_pattern_matching: check for single-arm match
• clippy: dbg_macro: don't remove dbg! in arbitrary expressions
• clippy: don't suggest unnameable types in box_default, let_underscore_untyped
• clippy: enhance needless_collect: lint in method/function arguments that take an IntoIterator
• clippy: fix invalid_regex not recognizing new syntax introduced after regex-1.8.0
• clippy: fix some suggestions generated by the option_if_let_else lint
• clippy: ignoring let_underscore_untyped warnings in code from proc macros
• clippy: rename integer_arithmetic
• rust-analyzer: consider block impls in lookup_impl_assoc_item_for_trait_ref
• rust-analyzer: expand format_args! with more details
• rust-analyzer: add moved-out-of-ref diagnostic
• rust-analyzer: highlight used trait assoc items when cursor is on trait import or trait bound
• rust-analyzer: render hover actions for closure captures and sig
• rust-analyzer: support C string literals
• rust-analyzer: consider all tokens in macro expr when analyzing locals
• rust-analyzer: fix preorder_expr skipping the else block of let-else statements
• rust-analyzer: fix evaluating negation for floating point types
• rust-analyzer: handle match scrutinee in closure captures
• rust-analyzer: introduce new type var when expectation for ref pat is not ref
• rust-analyzer: place type inlay hints after the item and without left-padding
• rust-analyzer: process macro_use prelude in semantic scope resolver

Rust Compiler Performance Triage

There were a few regressions, but most were expected, and one in particular (PR #111807) is expected yield gains in object code performance at the expense of a slight compile-time hit. There are a couple PR's that need future followup, namely PRs #111364 and #111524.

Triage done by @pnkfelix. Revision range: 3ea9ad53..cda5becc

3 Regressions, 2 Improvements, 5 Mixed; 2 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

• [disposition: merge] eRFC: single-file packages ("cargo script") integration

Tracking Issues & PRs

• [disposition: merge] Stabilize inline asm for LoongArch64 (editor's note: "LoongArch" is not a typo)
• [disposition: merge] Uplift clippy::invalid_utf8_in_unchecked lint
• [disposition: merge] Uplift clippy::cast_ref_to_mut lint
• [disposition: merge] Uplift clippy::undropped_manually_drops lint
• [disposition: merge] Make pointer_structural_match normal and warn
• [disposition: merge] [mir-opt] SimplifyLocals should also clean up debuginfo
• [disposition: merge] Remove structural match from TypeId
• [disposition: merge] Fix docs for alloc::realloc

New and Updated RFCs

• [new] RFC: #[export] (dynamically linked crates)
• [new] Generic Futures

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:

• No RFCs issued a call for testing 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.

Upcoming Events

Rusty Events between 2023-05-24 - 2023-06-21 🦀

Virtual

• 2023-05-25 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
  • Practical Monads
• 2023-05-25 | Virtual (Ciudad de México, MX) | Rust MX
  • Proyecto "Taller de Rust"
• 2023-05-25 | Virtual (Karlsruhe, DE) | The Karlsruhe Functional Programmers Meetup Group
  • Stammtisch (gemeinsam mit der C++ UG KA) - various topics, from C++ to Rust
• 2023-05-25 | Virtual (Raleigh, NC, US) | Triangle BitDevs
  • Rust for Bitcoiners
• 2023-05-25 | Virtual (San Francisco, CA, US) | Data + AI Online Meetup
  • D3L2: Discussing Rust, Ballista, Ray SQL, DataFusion with Andy Grove
• 2023-05-30 | Virtual (Dallas, TX, US) | Dallas Rust
  • Last Tuesday
• 2023-05-31 | Virtual (Chicago, IL, US) | Chicago Healthcare Cloud Technology Community
  • Rust for Mission-Critical AI: A Journey into Healthcare's Safest Language
• 2023-06-06 | Virtual (Austin, TX, US) | WebAssembly and WasmEdge
  • Monthly WasmEdge Community Meeting - Run Rust Warp in WasmEdge -- Alan, Poon Yong Quan
• 2023-06-06 | Virtual (Berlin, DE) | OpenTechSchool Berlin
  • Rust Hack and Learn
• 2023-06-06 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
  • Buffalo Rust User Group, First Tuesdays
• 2023-06-07 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2023-06-07 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
  • Rust-Meetup
• 2023-06-08 | Virtual (Nürnberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2023-06-13 | Virtual (Dallas, TX, US) | Dallas Rust
  • Second Tuesday
• 2023-06-20 | Virtual (Berlin, DE) | Berline.rs / OpenTechSchool Berlin
  • Rust Hack and Learn
• 2023-06-20 | Virtual (Washington, DC, US) | Rust DC
  • Mid-month Rustful
• 2023-06-21 | Virtual (Vancouver, BC, CA) | Vancouver Rust
  • Rust Study/Hack/Hang-out

Asia

• 2023-05-25 | Amsterdam, NL | Frontend Developer Meetup Amsterdam
  • Svelte Frontend Meetup (signup required) - Building a Svelte-Rust app using Tauri
• 2023-06-10 | Kuala Lumpur, MY | GoLang Malaysia
  • Rust Workshop/Hack and Learn Malaysia June 2023 | Event updates Telegram | Event group chat

Europe

• 2023-05-24 | Lyon, FR | Rust Lyon
  • Rust Lyon Meetup #4
• 2023-05-25 | Barcelona, ES | C++ Programmer Meetup.
  • Rust for C++ Developers.
• 2023-05-25 | Copenhagen, DK | Copenhagen Rust Community
  • Rust metup #36 at Adapt Agency!
• 2023-05-25 | Paris, FR | Rust Paris
  • Rust Paris meetup #59
• 2023-05-30 | Barcelona, ES | BcnRust
  • 10th BcnRust Meetup
• 2023-06-03 | Plovidv, BG | AeroRust
  • Space Conference - Plovdiv
• 2023-06-04 | Plovidv, BG | AeroRust
  • Space Conference : Nanosatellite embedded workshop
• 2023-06-08 | Aarhus, DK | Rust Aarhus
  • Rust Aarhus meetup #2 sponsored by BRØLSTÆRK
• 2023-06-08 | Zurich, CH | Rust Zurich
  • Unsafe, Miri, SIMD - June Meetup

Oceania

• 2023-05-30 | Canberra, ACT, AU | Canberra Rust User Group
  • May Meetup

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 guess the nicest example of this phenomenon is shared mutability. Programmers have been arguing for decades whether it is sharing xor mutability that causes memory safety bugs:

• "It's threads!" – shouted JavaScript and Python, and JS remained single-threaded, and Python introduced the GIL.
• "It's mutability!" – screamed Haskell and Erlang, and they made (almost) everything immutable.

And then along came Rust, and said: "you are fools! You can have both sharing and mutability in the same language, as long as you isolate them from each other."

– H2CO3 on rust-users

Thanks to Jacob Pratt 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