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

Newsletters

• This Week in Ars Militaris VII

Project/Tooling Updates

• actix-contrib-logger v0.1.0: drop-in replacement for the Actix Web HTTP Logger middleware

Observations/Thoughts

• [video] Rust 1.71.1
• Exploring the Rust compiler benchmark suite
• Pre-RFC: Sandboxed, deterministic, reproducible, efficient Wasm compilation of proc macros
• RustShip: a new Rust podcast

Rust Walkthroughs

• [video] Delightful command-line utilities with Rust
• ESP32 Standard Library Embedded Rust: Analog Temperature Sensing using the ADC
• Bare Metal Space Invaders
• [series] Distributed Tracing in Rust, Episode 2: tracing basics
• Secure database access using Ockam

Research

• Fixing Rust Compilation Errors using LLMs

Miscellaneous

• Shuttle Launchpad #6: A little CRUD
• [video] I failed to build multiplayer pong in Rust

Crate of the Week

This week's crate is document-features, a crate to extract documentation for the feature flags from comments in Cargo.toml.

Thanks to Zicklag 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.

• ZeroCopy - CI step "Set toolchain version" can fail without stopping CI job 1
• ZeroCopy - Prevent panics statically 1
• RON - Rusty byte strings in RON, deprecate base64 (byte) strings
• heed - create guides on ways to use heed
• Ockam - Use a user-friendly name for the shared services to show it in the tray menu
• Ockam - In the Share a service window, the Port should be renamed to Address and support such format
• Ockam - In the Share a service window, the Name attribute should not have the /service/ prefix
• Hyperswitch - remove unused function for merchant connector account

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

Updates from the Rust Project

342 pull requests were merged in the last week

• Restrict the parsing of count (RFC #3086)
• custom_mir: change Call() terminator syntax to something more readable
• add MIR validation for unwind out from nounwind functions + fixes to make validation pass
• add missing Clone/Debug impls to SMIR Trait related tys
• add projection obligations when comparing impl too
• add the relocation_model to the cfg
• avoid side-effects from try_coerce when suggesting borrowing LHS of cast
• check projection args before substitution in new solver
• const-eval: ensure we never const-execute a function marked rustc_do_not_const_check
• couple of global state and driver refactors
• deny FnDef in patterns
• do not mark shallow_lint_levels_on as eval_always
• fix a stack overflow with long else if chains
• fix argument removal suggestion around macros
• fix bad suggestion when wrong parentheses around a dyn trait
• fix suggestion for attempting to define a string with single quotes
• improve invalid_reference_casting lint
• instantiate response: no unnecessary new universe
• interpret/miri: call the panic_nounwind machinery the same way codegen does
• match scrutinee need necessary parentheses for structs
• normalize before checking if local is freeze in deduced_param_attrs
• normalize return type of deduce_future_output_from_obligations
• only consider object candidates for object-safe dyn types in new solver
• point at return type when it influences non-first match arm
• point out expectation even if we have TypeError::RegionsInsufficientlyPolymorphic
• probe when assembling upcast candidates so they don't step on eachother's toes in new solver
• separate consider_unsize_to_dyn_candidate from other unsize candidates
• speed up compilation of type-system-chess
• stabilize thread local cell methods
• synchronize with all calls to unpark in id-based thread parker
• upgrade std to gimli 0.28.0
• usage zero as language id for FormatMessageW()
• use unstable_target_features when checking inline assembly
• warn on inductive cycle in coherence leading to impls being considered not overlapping
• we are migrating to askama
• miri: C mem function shims: consistently treat "invalid" pointers as UB
• miri: avoid unnecessary Vec resize
• miri: on out-of-bounds error, show where the allocation was created
• miri: pin a version of serde without intransparent unreproducible binary blobs
• miri: replace hand-written binary search with Vec::binary_search_by
• miri: tree borrows: more comments in foreign_read transition
• miri: when reporting a heap use-after-free, say where the allocation was allocated and deallocated
• only run MaybeInitializedPlaces dataflow once to elaborate drops
• optimize DroplessArena arena allocation
• optimizing the rest of bool's Ord implementation
• don't panic in ceil_char_boundary
• expose core::error::request_value in std
• fix UB in std::sys::os::getenv()
• cleaner assert_eq! & assert_ne! panic messages
• inline strlen_rt in CStr::from_ptr
• cargo-credential-gnome-secret: dynamically load libsecret
• cargo: crate checksum lookup query should match on semver build metadata
• cargo: credential-providers: make 1password no longer built-in
• cargo: credential: rename cargo:basic to cargo:token-from-stdout
• cargo: fix: change the defaults to always check-in Cargo.lock
• cargo: improve error message for when no credential providers are available
• cargo: login: allow passing additional args to provider
• cargo: make cargo-credential-gnome-secret built-in as cargo:libsecret
• cargo: print environment variables for cargo run in extra verbose mode
• rustdoc: add warning block support in rustdoc
• rustdoc: add lint redundant_explicit_links
• rustdoc: fixes with --test-run-directory and relative paths
• rustfmt: prevent ICE when formatting item-only vec!{}
• rustfmt: remove newlines in where clauses for v2
• rustfmt: use OR operator in Cargo.toml license field
• clippy: iter_overeager_cloned: detect .cloned().map() and .cloned().for_each()
• clippy: new_without_default: include where clause in suggestions, make applicable
• clippy: useless_conversion: only lint on paths to fn items and fix FP in macro
• clippy: allow calling to_owned on borrowed value for implicit_clone
• clippy: check that the suggested method exists in unwrap_or_default
• clippy: correctly handle async blocks for NEEDLESS_PASS_BY_REF_MUT
• clippy: new lint: should_panic_without_expect
• rust-analyzer: add status bar button to toggle check on save state
• rust-analyzer: implement extern crate completion
• rust-analyzer: record import aliases in symbol index
• rust-analyzer: fix help text for rust-analyzer.check.invocation{Strategy,Location}
• rust-analyzer: fix signature help of methods from macros
• rust-analyzer: fix auto-import (and completions) importing #[doc(hidden)] items
• rust-analyzer: rewrite DeMorgan assist
• rust-analyzer: start hovering default values of generic constants
• rust-analyzer: increase the buffer size for discover project command
• rust-analyzer: suggest type completions for type arguments and constant completions for constant arguments
• rust-analyzer: the "add missing members" assists: implemented substitution of default values of const params
• rust-analyzer: upgrade lsp server

Rust Compiler Performance Triage

A week with very few real regressions and some good improvements through work done by @cjgillot who found a few spots where the compiler was doing unnecessary work.

Triage done by @rylev. Revision range: e845910..d4a881

Summary:

3 Regressions, 2 Improvements, 2 Mixed; 2 of them in rollups 28 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

• No RFCs entered Final Comment Period this week.

Tracking Issues & PRs

• [disposition: merge] Tracking Issue for const [u8]::is_ascii (const_slice_is_ascii)
• [disposition: merge] Implement From<[T; N]> for Rc<[T]> and Arc<[T]>
• [disposition: merge] Tracking Issue for Saturating type
• [disposition: merge] Implement From<{&,&mut} [T; N]> for Vec<T> where T: Clone
• [disposition: merge] Tracking Issue for os_str_bytes
• [disposition: merge] Tracking Issue for io::Error::other
• [disposition: merge] impl TryFrom<char> for u16
• [disposition: merge] rustdoc: show inner enum and struct in type definition for concrete type
• [disposition: merge] Replace old private-in-public diagnostic with type privacy lints
• [disposition: merge] Implement PartialOrd and Ord for Discriminant
• [disposition: merge] stop adding dropck outlives requirements for [T; 0]
• [disposition: merge] make Cell::swap panic if the Cells partially overlap
• [disposition: merge] Add note that Vec::as_mut_ptr() does not materialize a reference to the internal buffer
• [disposition: merge] Document lack of panic safety guarantees of Clone::clone_from
• [disposition: merge] Command: also print removed env vars
• [disposition: merge] impl Step for IP addresses

New and Updated RFCs

• [new] RFC: expose-fn-type

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 2023-08-23 - 2023-09-20 🦀

Virtual

• 2023-08-23 | Virtual (Linz, AT) | Rust Linz
  • Rust Meetup Linz - 32nd Edition
• 2023-08-24 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2023-08-24 | Virtual (Ciudad de México, MX) | Rust MX
  • Macros Procedurales y Metalenguajes en Rust
• 2023-09-05 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
  • Buffalo Rust User Group, First Tuesdays
• 2023-09-05 | Virtual (Munich, DE) | Rust Munich
  • Rust Munich 2023 / 4 - hybrid
• 2023-09-06 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2023-09-07 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2023-09-12 - 2023-09-15 | Virtual (Albuquerque, NM, US) | RustConf
  • RustConf 2023
• 2023-09-12 | Virtual (Dallas, TX, US) | Dallas Rust
  • Second Tuesday
• 2023-09-13 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
  • Monthly Meetup
• 2023-09-13 | Virtual (Cardiff, UK)| Rust and C++ Cardiff
  • The unreasonable power of combinator APIs
• 2023-09-14 | Virtual (Nuremberg, DE) | Rust Nuremberg
  • Rust Nürnberg online

Asia

• 2023-09-06 | Tel Aviv, IL | Rust TLV
  • RustTLV @ Final - September Edition

Europe

• 2023-08-23 | London, UK | Rust London User Group
  • LDN Talks Aug 2023: Rust London x RNL (The next Frontier in App Development)
• 2023-08-24 | Aarhus, DK | Rust Aarhus
  • Rust Aarhus Hack and Learn at Trifork
• 2023-08-30 | Copenhagen, DK | Copenhagen Rust Community
  • Rust metup #39 sponsored by Fermyon
• 2023-08-31 | Augsburg, DE | Rust Meetup Augsburg
  • Augsburg Rust Meetup #2
• 2023-09-05 | Munich, DE + Virtual | Rust Munich
  • Rust Munich 2023 / 4 - hybrid
• 2023-09-21 | Bern, CH | Rust Bern
  • Third Rust Bern Meetup

North America

• 2023-08-23 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2023-08-24 | Mountain View, CA, US | Mountain View Rust Meetup
  • Rust Meetup at Hacker Dojo
• 2023-09-06 | Bellevue, WA, US | The Linux Foundation
  • Rust Global
• 2023-09-12 - 2023-09-15 | Albuquerque, NM, US + Virtual | RustConf
  • RustConf 2023
• 2023-09-19 | San Francisco, CA, US | San Francisco Rust Study Group
  • Rust Hacking in Person

Oceania

• 2023-08-24 | Brisbane, QLD, AU | Rust Brisbane
  • August Meetup
• 2023-09-13 | Perth, WA, AU | Rust Perth
  • Rust Meetup 2: Lunch & Learn

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

[...] there's no benefit to haranguing people.

Unless they use three spaces for indentation. Those people need to be relentlessly mocked and publicly harassed until they see sense and use five spaces like all proper, civilised people do. Damn barbarians...

– Daniel Keep on rust-users

Thanks to Jonas Fassbender 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