fidzu : thunderbird

Firefox keeps evolving, and the community continues to play a big part in shaping what's next.

In this edition, you can get an early look at Project Nova through our latest foxfooding opportunity, explore Tab Groups on Android, join the conversation on Mozilla's latest browser choice research, and meet an Outreachy contributor whose journey reminds us why open source thrives through collaboration.

Get ready to dive in!

Hot from the oven: Join Project Nova foxfooding

We teased it in the last edition, and now it's here. Project Nova has finally arrived on Firefox Nightly, and you're invited to be an early tester! Get a look at Firefox's refreshed design as we put the finishing touches on the experience ahead of its broader release later this year. If you're curious about what's coming next, this is your chance to try it out, share your feedback, and help shape the final product.

Learn more

Monthly Community Call today!

Want to ask questions directly to the people working on Firefox? Join us for today's Monthly Community Call, where we'll discuss Project Nova and Firefox performance feature with members of the teams working on these projects. Join the call today, July 29, 2026, at 5:00 PM UTC, and bring your questions!

Watch our livestream

Tab groups arrives on Android

You've been calling out for tab group functionality on Firefox mobile and now Tab Groups have officially arrived on Firefox for Android! Tab Groups make it easier to organize related tabs into color-coded groups for work, travel, shopping, research, or whatever you're browsing. Give it a try, and if you have ideas for how it could be even better, let us know on Mozilla Connect.

Read more

From the Reddit Community

Mozilla recently shared new independent research examining how browser choice is shaped by the design of operating systems. The report explores the obstacles users can encounter when downloading, setting, or continuing to use their preferred browser, and argues that people should be able to choose their browser without unnecessary friction. Read the report, join the discussion, and share your perspective!

And of course, thanks to you for choosing Firefox!

Access the report

Community spotlight

Every contributor starts somewhere. In a recent blog post, Ananya Shree Sharma reflects on her journey through the Outreachy internship with Firefox. From navigating a large open source codebase for the first time to collaborating with mentors, learning new skills, and shipping meaningful improvements. Her story is a reminder that open source is as much about learning, mentorship, and community as it is about writing code. If you've ever wondered what it feels like to contribute to Firefox, Ananya's reflections offer an inspiring look at the experience and the people who make it possible.

Read more

---

P.S.

Enjoyed these updates? Subscribe to the Mozilla Community Newsletter and get the latest updates delivered straight to your inbox.

29 Jul 2026 9:04am GMT

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.bsky.social on Bluesky 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.

Want TWIR in your inbox? Subscribe here.

Updates from Rust Community

Newsletters

• Scientific Computing in Rust #20 (July 2026)

Project/Tooling Updates

• afrim 0.7.0: a generic input method framework
• Sharing Rust build work across Cargo worktrees with cargo-reapi
• exiftool-rs 0.7.0: localizing ExifTool's PrintConv values, not just its labels
• Announcing SeaORM 2.0
• kobe 0.37.0: easier to deploy and install
• kache 0.12.0: pluggable remotes, smarter GC, sharper diagnostics
• Progress toward compiling Linux with gccrs
• flodl 0.7.0: one dashboard view, repeated at every level
• samkhya 1.2.1 - the join-cardinality ceiling becomes provable
• BrewFS: a Rust and JuiceFS-like distributed filesystem

Observations/Thoughts

• Improving std::simd::swizzle_dyn
• Query cycles: A compiler murder mystery
• GDPatch: a versatile Godot mod loader
• Memory Safety Absolutists
• C++ to Rust Migration
• High-Performance Flat 2D Arrays in Rust with SIMD, L1 Cache
• Building Java-Rust Microservices with TeaQL: Models, Events, and Audit Intent
• How We Cut a Trading Bot's Reaction Time from ~2 Seconds to Milliseconds - by Moving Only the Hot Path to Rust
• ESP32 Server: Distributing HTTP/2 streams over TLS
• [video] Rust Berlin Talks · 23/07/2026

Rust Walkthroughs

• No Tokens Yet Does Not Mean a Rust LLM Stream Is Safe to Retry
• [series] Rama 101.2: Core Concepts
• [video] [series] What's Inside Axum?

Crate of the Week

This week's crate is cargo-efmt, a drop-in replacement for cargo fmt to support .editorconfig.

Thanks to kleines Filmröllchen for the self-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.

• No Calls for participation were submitted this week.

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.

• No Calls for papers or presentations were submitted this week.

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

570 pull requests were merged in the last week

Compiler

• apply RemoveNoopLandingPads post-monomorphization
• closures inherit #[optimize] from the enclosing function by default
• fix bool calling convention for aarch64, etc
• optimize escape_string_symbol()
• proc_macro: Fix cfg_attr inner attrs in file modules
• resolve: more preperation work for parallelizing the import resolution loop
• stabilize c-variadic function definitions

Library

• constify vec![1, 2, 3] macro
• core: implement Rng for references
• define a Simd type in minicore
• implement CovariantUnsafeCell
• implement str::copy_from_str
• iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>
• move std::io::buffered to alloc::io
• num: improve error messages for TryFromIntError
• str: add ASCII fast path to word_to_titlecase
• switch implementations of thread_local! for WASI

Cargo

• add haiku's dylib path
• diag: bound transitive unused dependency traversal
• git: Hide git fetch output without progress
• git: Suggest libgit2 if git-cli fails
• test: gate trim-paths tests on split debuginfo support
• toml: warn on hyphenated lint names and duplicates
• allow setting -Zembed-metadata value from the config
• enable build-dir layout v2 on nightly by default
• zsh completion: Add -p and --package flags for cargo add

Rustfmt

• allow file not found errors for external mods annotated with #[my_macro]
• discover modules via cfg_select!

Rustdoc

• add paths for linked associated items
• Retrieve cfg_attr information for derived impls for doc_cfg feature
• only build extern trait impls if needed
• only inline impls for local primitives

Clippy

• add EULER_GAMMA and GOLDEN_RATIO to approx_constant
• add assert_is_empty lint
• apply safety comment to compound assignment statement
• blocks_in_conditions: Don't lint if the block creates temporarie…
• call in_external_macro after running other checks in various places
• do not trigger clippy::exit when expression comes from an external macro
• duration_suboptimal_units: print the complete method name in the suggestion
• extend branches_sharing_code to match arms with a shared tail
• min_ident_chars lint short idents even if follows trait naming
• multiple_unsafe_ops_per_block: false positive in with taking an reference to a static, but not reading/writing it
• fix four_forward_slashes false positive on inner doc comments
• lint-page: add accessible labels to filters
• new lint: nonnull_unchecked_on_box_ptr
• perf: avoid per-call type and path work in unnecessary_mut_passed
• perf: find tab groups in doc comments without allocating
• rewrite EndianBytes lint pass

Rust-Analyzer

• add diagnostic for struct patterns which don't specify sub-patterns for its fields
• add parentheses for invert general expression
• attach db on worker threads in parallel analysis-stats inference
• change unsupported toolchain version to match reality
• discover protocol should only parse stdout
• do not detect #[rust_analyzer] as #[rust_analyzer::rust_fixture]
• don't offer replace_qualified_name_with_use on an unqualified path
• don't panic on a qualified path whose trait is not a trait
• don't pick a discriminant type larger than typeck's
• fix stale lock file
• fix .zip(None) call
• give impl_trait_with_diagnostics a cycle result
• make analysis-stats progress bar Unicode-safe
• merge_imports panic on invalid paths
• panic on macro-defined structs with unknown fields
• prefer alloc over std paths when preferNoStd is set
• record obligation chain for unimplemented trait diagnostics and show it
• replace detach with delete for ast::IdentPat
• resolve path on all namespace on resolve_path
• respect references.exclude[Tests/Imports] in references lens
• scoped lazy priming
• support inactive-code diagnostic in macros
• uses bool instead pat ty in guard

Rust Compiler Performance Triage

Several large improvements landed in the past week:

• rustdoc is on average roughly 16% faster across all of our doc benchmarks:
• rustdoc: Only inline impls for local primitives, 7% faster doc builds
• rustdoc: Only synthesize auto/blanket impls for documented items, another 7% faster doc builds
• rustdoc: Only build extern trait impls if needed, another 10% faster doc builds
• Early removal of no-op panic handling in debug builds. This speeds up Cargo by ~4% in cycle count.
• Optimize escape_string_symbol() sped up large include_bytes!/include_str! through changes to string escaping, avoiding a regression in upcoming LLVM 23 upgrade.

Great to see so many improvements!

Triage done by @simulacrum. Revision range: d527bc9b..ad0c9dce

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.

Tracking Issues & PRs

Rust

• Shallow resolve ty and const vars to their root vars, attempt 2
• Ensure inferred let pattern types are well-formed
• stabilize c_variadic_naked_functions
• lint against repeated repr attributes
• Stabilize passing 128-bit integers via vector registers with asm! on x86
• Add new invalid_markdown_table rustdoc lint
• allocations: document that they can be read-only
• allocations are allowed to grow (but not shrink)
• Tracking Issue for bool::toggle
• Tracking Issue for const_btree_len

• Add raw_borrows_via_references lint

• Never break between empty parens

Compiler Team (MCPs only)

• Wasm proc macro support

• group target modifier options under -T

• Optimize repr(Rust) enums by omitting tags in more cases involving uninhabited variants.

• Proposal for Adapt Stack Protector for Rust

Rust RFCs

• RFC: Refactor the libs team
• Cargo: hints.min-opt-level

Cargo

• feat(profile): Add built-in profile debug
• feat(toml): allow overriding inherited default-features in 2024

No Items entered Final Comment Period this week for Language Reference, Language Team, Leadership Council 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: Externref lang item for Wasm targets

Upcoming Events

Rusty Events between 2026-07-29 - 2026-08-26 🦀

Virtual

• 2026-07-30 | Virtual (Berlin, DE) | Rust Berlin
  • Rust Hack and Learn
• 2026-07-31 | Virtual (Girona, ES) | Rust Girona
  • Sessió setmanal de codificació / Weekly coding session
• 2026-08-01 | Virtual (Kampala, UG) | Rust Circle Meetup
  • Rust Circle Meetup
• 2026-08-02 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Rust Deep Learning: First Sunday
• 2026-08-03 | Virtual (Global) | Rust Maven
  • Workshop: Add tests to an open source Rust project
• 2026-08-04 | Virtual (London, UK) | Women in Rust
  • 👋 Community Catch Up
• 2026-08-04 | Virtual (Tel Aviv-yafo, IL) | Rust 🦀 TLV
  • שיחה חופשית ווירטואלית על ראסט
• 2026-08-05 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
  • Operating Systems Book Club: Execution and Scheduling
• 2026-08-05 | Virtual (Indianapolis, IN, US) | Indy Rust
  • Indy.rs - with Social Distancing
• 2026-08-07 | Virtual (Girona, ES) | Rust Girona
  • Sessió setmanal de codificació / Weekly coding session
• 2026-08-11 | Virtual (Dallas, TX, US) | Dallas Rust User Meetup
  • Second Tuesday
• 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
• 2026-08-18 | 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

Africa

• 2026-08-11 | 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

Europe

• 2026-07-29 | Poland, PL | Rust Poland
  • Rust Poland x Kraków #10
• 2026-07-30 | Copenhagen, DK | Copenhagen Rust Community
  • Rust meetup #70
• 2026-07-30 | Manchester, UK | Rust Manchester
  • Rust Manchester July Code Night
• 2026-08-06 | Oxford, UK | Oxford ACCU/Rust Meetup.
  • ACCU/Rust Summer social
• 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

North America

• 2026-07-30 | Atlanta, GA, US | Rust Atlanta
  • Rust-Atl
• 2026-08-01 | Boston, MA, US | Boston Rust Meetup
  • Chinatown Rust Lunch, Aug 1
• 2026-08-04 | Boston, MA, US | Boston Rust Meetup
  • Evening Boston Rust Meetup at Red Hat, Aug 4
• 2026-08-06 | Mountain View, CA, US | Hacker Dojo
  • RUST MEETUP at HACKER DOJO
• 2026-08-06 | Saint Louis, MO, US | STL Rust
  • Shipping Temporal: How a Global Rust Ecosystem Built Chrome's Newest Web API
• 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 | Rust Bay Area
  • Rust Bay Area August Meetup
• 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

Oceania

• 2026-07-30 | Melbourne, AU | Rust Melbourne
  • Rust Melbourne July 2026

South America

• 2026-08-08 | São Paulo, SP | Rust-SP
  • Rust SP - Aug/2026

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

So let's talk about what the process has looked like for Netstack3. For 11 months, the team has been ramping up a dogfooding program. At peak, that program has seen about 60 devices running nearly 24/7 in developers' homes.

Again, if this were any other netstack, we would have expected to uncover a giant mountain of bugs in that time. So, over the past year, how many bugs did the team uncover in the field?

Three.

- Josh Liebow-Feeser on his blog

llogiq again has no one to thank for a suggestion, so he is thankful to himself for finding this quote instead.

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

29 Jul 2026 4:00am GMT

Bugs resolved in Moz-Phab 2.15.4:

• bug 2058150 moz-phab patch crashes with KeyError when a stack relative is not visible to the user

Discuss these changes in #engineering-workflow on Slack or #Conduit Matrix.

1 post - 1 participant

Read full topic

27 Jul 2026 4:15pm GMT