This Week In Rust: This Week in Rust 664

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.
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Updates from Rust Community

Official

• Call for testing: Restricting trait implementability and field mutability

Foundation

• Rust Team Health Summit: September 8 in Montréal


• Catching Up with the Rust Content Team: RustWeek Interviews and a New Changelog Series

Newsletters

• This Month in Rust OSDev: July 2026

Project/Tooling Updates

We are making changes to the Project/Tooling Updates Section - see here for more details

• Bevy's Sixth Birthday


• fearless_simd v0.7: 64-bit integers, improved generics, SSE2, and upcoming v1.0


• vairedb 0.1.0 - Cloud Native Distributed Analytical Database


• OXVG 0.0.7: introducing an SVG-to-JSX transformer to the OXVG toolchain


• HTML, JavaScript, CSS should have died long ago


• Even more formal verification for BPF


• kache 0.14.0: debuggable restores and cross-clone convergence


• kobe 0.39.0: hardening the cluster-lease lifecycle


• renew 0.1.1: a deterministic, code-first game engine


• GRIT 1.1: type-check your quantized tensors


• floDl: Introducing AMD GPU support


• git-cache-proxy: read-only cache for git

Observations/Thoughts

• A Vision for Cargo


• Cylic trait implementations: motivation


• Rust SIMD on the GPU


• Rewriting in Rust: Performance, Failures, 2026 Reality Check


• RangeFrom, Part 1..: History and background


• Typed Conversations: Make Illegal Agent Dialogues Unrepresentable


• ECQV: implicit certificates, and why I kept them out of the project that motivated them


• TLS Handshakes: Measuring the Performance of 4 Cryptography Libraries


• Building scalable backend services with Rust and PostgreSQL


• PoC for universal hardware-in-the-loop HAL test suite — Tweede golf


• [video] FLOSS 878 - A Tool With Opinions

Rust Walkthroughs

• Downcasting Arcs in Rust


• Profiling Rust with hotpath-rs: The Complete Guide - From SQL Queries to CPU Sampling


• A chip-agnostic architecture for bare-metal embedded Rust

Research

• Rust Coreutils: Rebuilding Unix Foundations in a Modern Language

Miscellaneous

Crate of the Week

This week's crate is literator, a crate for efficiently displaying the items of an iterator without temporary allocations.

Thanks to Nora for the suggestion!

Please submit your suggestions and votes for next week!

Calls for Testing

An important step for RFC implementation is for people to experiment with the
implementation and give feedback, especially before stabilization.

If you are a feature implementer and would like your RFC to appear in this list, add a
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.

No calls for testing were issued this week by
Rust,
Cargo,
Rustup or
Rust language RFCs.

Let us know if you would like your feature to be tracked as a part of this list.

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.

• Diesel - Improve the documentation of our derives

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 Bluesky 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.

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 Bluesky or Mastodon!

Updates from the Rust Project

698 pull requests were merged in the last week

Compiler

• check the fallback map before queueing child in visible_parent_map breadth-first search


• enable polonius alpha on nightly


• improve canonical_param_env_cache


• interpret: skip deref-projection validity checks when they are not needed


• optimize crate resolution for large workspace


• optimize handling of solver errors


• optimize try_evaluate_obligations


• perf: cache already-checked types in the privacy visitor


• perf: lock-free root fast paths for hygiene queries


• perf: skip irrelevant foreign impls when building the specialization graph


• perf: store the fulfillment engine inline in ObligationCtxt


• shallow resolve ty and const vars to their root vars, attempt 2


• speed up EverInitializedPlaces


• split apply_primary_terminator_effect


• stabilize c_variadic_naked_functions

Library

• add fast path to escape_string_symbol


• core: generalize BorrowedCursor::ensure_init


• hint that memchr returns an in-bounds index


• implement <OnceCell,OnceLock>::new_init


• implement to_string() on ByteStr and ByteString


• introduce a PinSafePointer trait that generalizes PinCoerceUnsized


• mark const ptr methods and free functions as inline(always) to match *mut


• optimize slice::contains for one-byte BytewiseEq types


• single-pass ASCII lower/upper case conversion


• stabilize fs_set_times

Cargo

• docs(changelog): Pull the --verbose item


• docs(ref): Add missing config env variables


• feat(log): emit build-started JSON message with run_id


• feat(profile): Add built-in profile debug


• feat(resolver): Report the min-publish-age in the lock message


• feat(toml): allow overriding inherited default-features in 2024


• feat(trim-paths): emit unremap files for final artifacts


• fix(clean): respect target with --doc


• fix(diag): Ensure diagnostic titles work without snippets


• fix(diag): Gate blanket_hint_mostly_unused with -Zprofile-hint-mostly-unused


• fix(diag): Remove complexity, perf, and nursery lint groups


• fix(git): Avoid use of git's core.fsmonitor


• fix(lock): Use more accurate 'highest, rather than 'latest'


• fix(resolver): Make min-publish-age relative to --publish-time


• fix(trim-paths): /cargo/deps fallback sources


• fix(trim-paths): workspace remap under -Zroot-dir


• refactor(resolver): resolve() does not need an optional gctx


• revert(compiler): forward verbose flag to rustc for local crates


• test(trim-paths): exercise unremap files with debuggers


• doc: don't use mergeable info and json together


• fix funding link


• refactor: remove unnecessary mut in sources


• test: handle non-deterministic compilation order

Rustdoc

• Create output file after we checked that the standalone markdown file is valid


• Do not take doc(cfg()) into account when filtering doctests

Clippy

• cast_possible_truncation: fix try_from suggestion expanding macros


• don't lint semicolon_if_nothing_returned in #[automatically_derived] …


• fix needless_range_loop suggests wrongly for nested index


• needless_bool: lint the early-return guard form


• new lint: nonzero operators and methods


• redundant_pattern_matching: parenthesize guarded matches! suggestion


• unwrap_or_default: respect MSRV for raw-pointer Default impls

Rust-Analyzer

• account for trailing line continuations in byte strings


• support #[rustc_must_implement_one_of] in the assists


• add replace_arith_with_strict assist


• term_search exclude useless target type


• add parens on some common cases for type_mismatch


• allow struct literals in match guards inside let exprs


• always allocate anon consts for c-strings/byte-strings literals


• avoid array len type mismatch with string panic


• avoid escaping bound vars produced by infer_method_call's skip_binder


• bound macro expansion depth across body and block boundaries


• do not consider locals of async fn as upvars of the returned coroutine


• do not declare the value NS constructor for structs/enum variants if it does not exist


• don't panic when a lifetime is passed to an ident metavariable


• fix 'no entry found for key' panic in VFS


• fix upvars query of const block inside closure


• fixed positive diagnostic for valid code


• initialize macro_depth to the file's macro depth in docs.rs and assoc.rs


• let Param::parent_fn return function for BuiltinDeriveImplMethod methods


• normalize associated types in orphan checks


• off-by-one in lifetime binders when lowering dyn Trait<'a>


• optimize memory usage of the item tree


• parse inline asm with keyword as operand name


• parse or pattern after range pattern


• preserve trailing text when InsertReplaceEdit is unsupported


• remove extra spaces in full function signatures


• support macros in #[doc] attributes in IDE features


• unresolved type variables shouldn't escape impl selection


• when searching for a pub macro, consider it available to reverse dependencies

Rust Compiler Performance Triage

This week so many new performance improvements landed that we needed to roll 10 of them up together to keep the bors queue manageable, great work!
Also new is the LLVM 23 update which caused massive compile-time, run-time, bootstrap time and artifact size improvements.
These improvements are reduced by the merge of Polonius Alpha on nightly causing a 3.0% regression. There still seems to be some potential to mitigate this regression.

Triage done by @JonathanBrouwer.
Revision range: 65dd30fb..771916f9

Summary:

1 Regression, 4 Improvements, 7 Mixed; 5 of them in rollups
25 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:

• Cargo: hints.min-opt-level


• Add extern "custom"

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.

Tracking Issues & PRs

• std: map ENOTSUP to ErrorKind::Unsupported- #158580


• feat: add symmetric PartialEq impls for Vec, &[T], &mut [T] versus Cow<'_, [T]>


• Add Default implementation for std::sync::Once


• Extend dropping_{references,copy_types} lints to drop_in_place


• lint on more incorrect usages of core::ffi::c_void


• target_features: sse (or at least avx2) is incompatible with soft-float ABI


• Make let-else respect macro_rules expr metavariable grouping


• PowerPC inline ASM: Fix scalar floats being in the wrong vector lane on little endian


• stabilize Box::take


• make closures act like MaybeDangling


• enable next solver by default in orphanck


• Error on projection of dyn noncompat type in old trait solver


• Stabilize -Zprofile-sample-use

• Stop using dlltool for generating import libraries on MinGW


• Promote riscv64a23-unknown-linux-gnu to Tier 2 with host tools


• Drop tier 2 i686-pc-windows-gnu host tools

• Allocate more funds for the Funding team in 2026


• Allocate more funds to 2026 travel budget

No Items entered Final Comment Period this week for
Rust RFCs,
Language Reference,
Cargo,
Language Team or
Unsafe Code Guidelines.
Let us know if you would like your PRs, Tracking Issues or RFCs to be tracked as a part of this list.

New and Updated RFCs

• RFC: Support External Linkers

Upcoming Events

Rusty Events between 2026-08-12 - 2026-09-09 🦀

Virtual

• 2026-08-13 | Virtual (Berlin, DE) | Rust Berlin
  
  
  • Rust Hack and Learn
  
  
  
  


• 2026-08-13 | Virtual (Nürnberg, DE) | Rust Nuremberg
  
  
  • Rust Nürnberg online
  
  
  
  


• 2026-08-14 | Virtual (Girona, ES) | Rust Girona
  
  
  • Sessió setmanal de codificació / Weekly coding session
  
  
  
  


• 2026-08-16 | Virtual (Bangalore, IN) | Embedded Rust
  
  
  • Silicon Sundays #2
  
  
  
  


• 2026-08-18 | Virtual (Washington, DC, US) | Rust DC
  
  
  • Mid-month Rustful
  
  
  
  


• 2026-08-19 | Hybrid (Vancouver, BC, CA) | Vancouver Rust
  
  
  • Dealing with Dependencies
  
  
  
  


• 2026-08-20 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
  
  
  • August, 2026 SRUG (Seattle Rust User Group) Meetup
  
  
  
  


• 2026-08-20 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
  
  
  • Tock OS Part #5 — Wireless Communication with the IEEE 802.15.4 protocol
  
  
  
  


• 2026-08-21 | Virtual (Girona, ES) | Rust Girona
  
  
  • Sessió setmanal de codificació / Weekly coding session
  
  
  
  


• 2026-08-25 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  
  
  • Fourth Tuesday
  
  
  
  


• 2026-08-27 | Virtual (Berlin, DE) | Rust Berlin
  
  
  • Rust Hack and Learn
  
  
  
  


• 2026-08-28 | Virtual (Girona, ES) | Rust Girona
  
  
  • Sessió setmanal de codificació / Weekly coding session
  
  
  
  


• 2026-08-31 | Virtual (Global) | Rust Maven
  
  
  • Workshop: Add tests to an open source Rust project
  
  
  
  


• 2026-09-01 | Virtual (Global) | Rust Maven
  
  
  • Tauri: Cross-Platform desktop applications with Rust and web technologies
  
  
  
  


• 2026-09-02 | Virtual (Indianapolis, IN, US) | Indy Rust
  
  
  • Indy.rs - with Social Distancing
  
  
  
  


• 2026-09-04 | Virtual (Girona, ES) | Rust Girona
  
  
  • Sessió setmanal de codificació / Weekly coding session
  
  
  
  


• 2026-09-08 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  
  
  • Second Tuesday
  
  
  
  


• 2026-09-08 | Virtual (London, UK) | Women in Rust
  
  
  • 👋 Community Catch Up
  
  
  
  

Africa

• 2026-09-08 | Johannesburg, ZA | Johannesburg Rust Meetup
  
  
  • Rust's extended standard library
  
  
  
  

Asia

• 2026-08-22 | Bangalore, IN | Rust Bangalore
  
  
  • August 2026 Rustacean Meetup
  
  
  
  


• 2026-08-22 | Delhi, IN | Rust Delhi
  
  
  • Rust Delhi X SciPy India Meetup
  
  
  
  


• 2026-08-22 | Noida, IN | SciPy India
  
  
  • Scientific Computing in Rust and Python
  
  
  
  


• 2026-08-29 | Pune, IN | Rust Pune
  
  
  • Rust Pune Meetup: August 2026
  
  
  
  

Europe

• 2026-08-13 | Switzerland, CH | PostTenebrasLab
  
  
  • Rust Meetup Geneva
  
  
  
  


• 2026-08-18 | Aarhus, DK | Rust Aarhus
  
  
  • Hack Night: Trust but verify the LLM
  
  
  
  


• 2026-08-18 | Leipzig, DE | Rust - Modern Systems Programming in Leipzig
  
  
  • Topic TBD
  
  
  
  


• 2026-08-20 | Frankfurt, DE | Rust Rhein-Main
  
  
  • Building an acoustic camera with egui and embassy
  
  
  
  


• 2026-08-27 | Manchester, UK | Rust Manchester
  
  
  • Rust Manchester August Talks
  
  
  
  

North America

• 2026-08-13 | Lehi, UT, US | Utah Rust
  
  
  • Utah Rust August Meetup
  
  
  
  


• 2026-08-13 | San Diego, CA, US | San Diego Rust
  
  
  • San Diego Rust August Meetup - Back in person!
  
  
  
  


• 2026-08-15 | San Francisco, CA, US | Flower
  
  
  • BOG-A-THON 3
  
  
  
  


• 2026-08-18 | San Francisco, CA, US | San Francisco Rust Study Group
  
  
  • Rust Hacking in Person
  
  
  
  


• 2026-08-19 | Hybrid (Vancouver, BC, CA) | Vancouver Rust
  
  
  • Dealing with Dependencies
  
  
  
  


• 2026-08-19 | San Francisco, CA, US | Bay Area Rust
  
  
  • Bay Area Rust August Meetup
  
  
  
  


• 2026-08-20 | Mountain View, CA, US | Hacker Dojo
  
  
  • RUST MEETUP at HACKER DOJO
  
  
  
  


• 2026-08-20 | New York, NY, US | Rust NYC
  
  
  • Rust NYC: 'Data Shapes Your Memory' and 'Rust in Peace'
  
  
  
  


• 2026-08-20 | Hybrid (Seattle, WA, US) | Seattle Rust User Group
  
  
  • August, 2026 SRUG (Seattle Rust User Group) Meetup
  
  
  
  


• 2026-08-26 | Austin, TX, US | Rust ATX
  
  
  • Rust Lunch - Fareground
  
  
  
  


• 2026-08-26 | Los Angeles, CA, US | Rust Los Angeles
  
  
  • Rust LA August! Rust in Quantum Computing
  
  
  
  


• 2026-08-27 | Atlanta, GA, US | Rust Atlanta
  
  
  • Rust-Atl
  
  
  
  


• 2026-09-03 | Saint Louis, MO, US | STL Rust
  
  
  • Cryptography + Quantum Computers
  
  
  
  


• 2026-09-08 | Montreal, QC, CA | Rust Foundation
  
  
  • Rust Teams Health Summit
  
  
  
  


• 2026-09-08 - 2026-09-11 | Montreal, QC, CA | RustConf 2026
  
  
  • RustConf 2026, Hosted by the Rust Foundation
  
  
  
  


• 2026-09-09 | Montreal, QC, CA | Women in Rust
  
  
  • RustConf Coffee Break Meetup
  
  
  
  

Oceania

• 2026-08-27 | Melbourne, AU | Rust Melbourne
  
  
  • Rust Melbourne 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

The AI discussion was already put to bed as off topic and derailing. Do not summon the Mods so carelessly, as they are wroth, and filled with cruel vengeance.

– Simon Buchan 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


• ericseppanen


• extrawurst


• U007D


• mariannegoldin


• bdillo


• opeolluwa


• bnchi


• KannanPalani57


• tzilist

Email list hosting is sponsored by The Rust Foundation

Discuss on r/rust