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 Rust 1.74.1
• Cargo cache cleaning

Newsletters

• This Month in Rust OSDev: November 2023

Project/Tooling Updates

• rust-analyzer changelog #211
• PC Music Generator
• Announcing mfio - Completion I/O for Everyone
• Watchexec Library 3.0 and CLI 1.24
• [series] Spotify-Inspired: Elevating Meilisearch with Hybrid Search and Rust

Observations/Thoughts

• Rust Is Beyond Object-Oriented, Part 3: Inheritance
• Being Rusty: Discovering Rust's design axioms
• Non-Send Futures When?
• for await and the battle of buffered streams
• poll_progress
• Rust and ThreadX - experiments with an RTOS written in C, a former certified software component
• Nine Rules for SIMD Acceleration of Your Rust Code (Part 1): General Lessons from Boosting Data Ingestion in the range-set-blaze Crate by 7x
• Contributing to Rust as a novice
• [audio] Exploring Rust's impact on efficiency and cost-savings, with Stefan Baumgartner

Rust Walkthroughs

• Common Mistakes with Rust Async
• Embassy on ESP: UART Transmitter
• Writing a CLI Tool in Rust with Clap
• Memory and Iteration
• Getting Started with Axum - Rust's Most Popular Web Framework
• Exploring the AWS Lambda SDK in Rust
• Practical Client-side Rust for Android, iOS, and Web
• [video] Advent of Code 2023

Miscellaneous

• Turbofish ::<>
• Rust Meetup and user groups
• Adopting Rust: the missing playbook for managers and CTOs
• SemanticDiff 0.8.8 adds support for Rust

Crate of the Week

This week's crate is io-adapters, a crate tha lets you convert between different writeable APIs (io vs. fmt).

Thanks to Alex Saveau for the self-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.

• greptimedb - API improvement for pretty print sql query result in http output 1
• greptimedb - Unify builders' patterns
• tokio - Run loom tests in oss-fuzz 4
• Ockam - Library - Validate CBOR structs according to the cddl schema for kafka/protocol_aware and nodes/services
• Ockam - Command - refactor to use typed interfaces to implement commands for relays
• Ockam - Make install.sh not fail when the latest version is already installed
• zerocopy - Use cargo-semver-checks to make sure derive feature doesn't change API surface
• zerocopy - Verify that all-jobs-succeeded CI job depends on all other jobs
• Hyperswitch - [REFACTOR]: [Nuvei] MCA metadata validation
• Hyperswitch - [Feature] : [Noon] Sync with Hyperswitch Reference
• Hyperswitch - [BUG] : MCA metadata deserialization failures should be 4xx
• Hyperswitch - [Feature] : [Zen] Sync with Hyperswitch Reference

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

Updates from the Rust Project

391 pull requests were merged in the last week

• introduce support for async gen blocks
• implement 2024-edition lifetime capture rules RFC
• riscv32 platform support
• add teeos std impl
• never_patterns: Parse match arms with no body
• rustc_symbol_mangling,rustc_interface,rustc_driver_impl: Enforce rustc::potential_query_instability lint
• add ADT variant infomation to StableMIR and finish implementing TyKind::internal()
• add deeply_normalize_for_diagnostics, use it in coherence
• add comment about keeping flags in sync between bootstrap.py and bootstrap.rs
• add emulated TLS support
• add instance evaluation and methods to read an allocation in StableMIR
• add lint against ambiguous wide pointer comparisons
• add method to get type of an Rvalue in StableMIR
• add more SIMD platform-intrinsics
• add safe compilation options
• add support for gen fn
• add support for making lib features internal
• added shadowed hint for overlapping associated types
• avoid adding builtin functions to symbols.o
• avoid instantiating infer vars with infer
• change prefetch to avoid deadlock
• compile-time evaluation: detect writes through immutable pointers
• coverage: be more strict about what counts as a "visible macro"
• coverage: merge refined spans in a separate final pass
• coverage: simplify the heuristic for ignoring async fn return spans
• coverage: use SpanMarker to improve coverage spans for if ! expressions
• dedup for duplicate suggestions
• discard invalid spans in external blocks
• do not parenthesize exterior struct lit inside match guards
• don't include destruction scopes in THIR
• don't print host effect param in pretty path_generic_args
• don't warn an empty pattern unreachable if we're not sure the data is valid
• enforce must_use on associated types and RPITITs that have a must-use trait in bounds
• explicitly implement DynSync and DynSend for TyCtxt
• fix is_foreign_item for StableMIR instance
• fix const drop checking
• fix in-place collect not reallocating when necessary
• fix parser ICE when recovering dyn/impl after for<...>
• fix: correct the arg for 'suggest to use associated function syntax' diagnostic
• generalize LLD usage in bootstrap
• generalize: handle occurs check failure in aliases
• implement --env compiler flag (without tracked_env support)
• implement repr(packed) for repr(simd)
• improve print_tts
• interpret: make numeric_intrinsic accessible from Miri
• make async generators fused by default
• make sure panic_nounwind_fmt can still be fully inlined (e.g. for panic_immediate_abort)
• only check principal trait ref for object safety
• pretty print Fn<(..., ...)> trait refs with parentheses (almost) always
• privacy: visit trait def id of projections
• provide context when ? can't be called because of Result<_, E>
• rearrange default_configuration and CheckCfg::fill_well_known
• recurse into refs when comparing tys for diagnostics
• remove PolyGenSig since it's always a dummy binder
• remove the precise_pointer_size_matching feature gate
• resolve associated item bindings by namespace
• streamline MIR dataflow cursors
• structured use suggestion on privacy error
• tell MirUsedCollector that the pointer alignment checks calls its panic symbol
• tip for define macro name after macro_rules!
• tweak .clone() suggestion to work in more cases
• tweak unclosed generics errors
• unescaping cleanups
• uplift the (new solver) canonicalizer into rustc_next_trait_solver
• use immediate_backend_type when reading from a const alloc
• use default params until effects in desugaring
• miri: fix promising a very large alignment
• miri: fix x86 SSE4.1 ptestnzc
• miri: move some x86 intrinsics code to helper functions in shims::x86
• miri: return MAP_FAILED when mmap fails
• stablize arc_unwrap_or_clone
• add LinkedList::{retain,retain_mut}
• simplify Default for tuples
• restore const PartialEq
• split Vec::dedup_by into 2 cycles
• futures: fillBuf: do not call poll_fill_buf twice
• futures: FuturesOrdered: use 64-bit index
• futures: FuturesUnordered: fix clear implementation
• futures: use cfg(target_has_atomic) on no-std targets
• cargo: spec: Extend PackageIdSpec with source kind + git ref for unambiguous specs
• cargo toml: disallow inheriting of dependency public status
• cargo toml: disallow [lints] in virtual workspaces
• cargo: schema: Remove reliance on cargo types
• cargo: schemas: Pull out mod for proposed schemas package
• cargo: trim-paths: assert OSO and SO cannot be trimmed
• cargo: avoid writing CACHEDIR.TAG if it already exists
• cargo: fix bash completion in directory with spaces
• cargo: explicitly remap current dir by using .
• cargo: print rustc messages colored on wincon
• cargo: limit exported-private-dependencies lints to libraries
• rustdoc-search: do not treat associated type names as types
• rustdoc: Don't generate the "Fields" heading if there is no field displayed
• rustdoc: Fix display of features
• rustdoc: do not escape quotes in body text
• rustdoc: remove unused parameter reversed from onEach(Lazy)
• bindgen: support float16
• rustfmt: add StyleEdition enum and StyleEditionDefault trait
• clippy: fix(ptr_as_ptr): handle std::ptr::null{_mut}
• clippy: needless_borrows_for_generic_args: Handle when field operand impl Drop
• clippy: uninhabited_reference: new lint
• clippy: add a function to check whether binary oprands are nontrivial
• clippy: fix is_from_proc_macro patterns
• rust-analyzer: check if lhs is also a binexpr and use its rhs in flip binexpr assist
• rust-analyzer: fallback to method resolution on unresolved field access with matching method name
• rust-analyzer: add trait_impl_reduntant_assoc_item diagnostic
• rust-analyzer: allow navigation targets to be duplicated when the focus range lies in the macro definition site
• rust-analyzer: implicit format args support (hooray!)
• rust-analyzer: prioritize import suggestions based on the expected type
• rust-analyzer: fix WideChar offsets calculation in line-index
• rust-analyzer: fix panic with closure inside array len
• rust-analyzer: bug in extract_function.rs
• rust-analyzer: don't emit "missing items" diagnostic for negative impls
• rust-analyzer: don't print proc-macro panic backtraces in the logs
• rust-analyzer: fix concat_bytes! expansion emitting an identifier
• rust-analyzer: fix completion failing in format_args! with invalid template
• rust-analyzer: fix diagnostics panicking when resolving to different files due to macros
• rust-analyzer: fix item tree lowering pub(self) to pub()
• rust-analyzer: fix runnable cwd on Windows
• rust-analyzer: fix token downmapping being quadratic
• rust-analyzer: fix view mir, hir and eval function not working when cursor is inside macros
• rust-analyzer: insert fn call parens only if the parens inserted around field name
• rust-analyzer: make drop inlay hint more readable
• rust-analyzer: resolve Self type references in delegate method assist
• rust-analyzer: smaller spans for unresolved field and method diagnostics
• rust-analyzer: make ParamLoweringMode accessible
• rust-analyzer: query for nearest parent block around the hint to resolve
• rust-analyzer: replace doc_comments_and_attrs with collect_attrs
• rust-analyzer: show placeholder while run command gets runnables from server
• rustc-perf: add support for benchmarking Cranelift codegen backend

Rust Compiler Performance Triage

A quiet week overall. A few smaller crate (e.g., helloworld) benchmarks saw significant improvements in #118568, but this merely restores performance regressed earlier.

Triage done by @simulacrum. Revision range: 9358642..5701093

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

69 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:

• Merge RFC 3531: "Macro fragment specifiers edition policy"

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 Bound::map
• [disposition: merge] Stabilize THIR unsafeck
• [disposition: merge] Exhaustiveness: reveal opaque types properly
• [disposition: merge] Properly reject default on free const items
• [disposition: merge] Make inductive cycles in coherence ambiguous always

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

• Async Drop
• Closure PartialEq and Eq

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:

• Cargo cache cleaning

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 2023-12-13 - 2024-01-10 🦀

Virtual

• 2023-12-14 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2023-12-14 | Virtual (Nuremberg, DE) | Rust Nuremberg
  • Rust Nürnberg online
• 2023-12-17 | Virtual (Tel Aviv, IL) | Code Mavens
  • Don't panic! - Our journey to error handling in Rust
• 2023-12-18 | Virtual (Munich, DE) | Rust Munich
  • Rust Munich 2023 / 5 - hybrid
• 2023-12-19 | Virtual (Berlin, DE) | OpenTechSchool Berlin
  • Rust Hack and Learn | Mirror
• 2023-12-19 | Virtual (Washington, DC, US) | Rust DC
  • Mid-month Rustful
• 2023-12-19 | Virtual (Linz, AT) Rust Linz
  • Rust Meetup Linz - 35th Edition
• 2023-12-20 | Virtual (Vancouver, BC, CA) | Vancouver Rust
  • Adventures in egui app dev
• 2023-12-26 | Virtual (Dallas, TX, US) | Dallas Rust
  • Last Tuesday
• 2023-12-28 | Virtual (Charlottesville, NC, US) | Charlottesville Rust Meetup
  • Crafting Interpreters in Rust Collaboratively
• 2024-01-03 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing

Asia

• 2023-12-16 | Delhi, IN | Rust Delhi
  • Meetup #4

Europe

• 2023-12-14 | Augsburg, DE | Rust - Modern Systems Programming in Leipzig
  • Augsburg Rust Meetup #4
• 2023-12-14 | Basel, CH | Rust Basel
  • Testing: Learn from the pros
• 2023-12-18 | Munich, DE + Virtual | Rust Munich
  • Rust Munich 2023 / 5 - hybrid
• 2023-12-19 | Heidelberg, DE | Nix Your Bugs & Rust Your Engines
  • Nix Your Bugs & Rust Your Engines #1
• 2023-12-19 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
  • Tauri, an Electron-alternative
• 2023-12-27 | Copenhagen, DK | Copenhagen Rust Community
  • Rust hacknight #1: CLIs, TUIs and plushies

North America

• 2023-12-13 | Chicago, IL, US | Deep Dish Rust
  • Rust Hack Night
• 2023-12-14 | Lehi, UT, US | Utah Rust
  • Sending Data with Channels w/Herbert Wolverson
• 2023-12-14 | Mountain View, CA, US | Mountain View Rust Meetup
  • Rust Meetup at Hacker Dojo
• 2023-12-15 | Somerville, MA, US | Boston Rust Meetup
  • Ball Square Rust Lunch
• 2023-12-19 | San Francisco, CA, US | San Francisco Rust Study Group
  • Rust Hacking in Person
• 2023-12-27 | Austin, TX, US | Rust ATX
  • Rust Lunch - Fareground
• 2024-01-09 | Minneapolis, MN, US | Minneapolis Rust Meetup
  • Minneapolis Rust Meetup Happy Hour

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

Sadly, the week went by without a nominated quote.

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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