Rust

Announcing Rust 1.68.2

2023-03-28

The Rust team has published a new point release of Rust, 1.68.2. Rust is a programming language that is empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, you can get 1.68.2 with:

rustup update stable

If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.68.2 on GitHub.

What's in 1.68.2 stable

Rust 1.68.2 addresses GitHub's recent rotation of their RSA SSH host key, which happened on March 24th 2023 after their previous key accidentally leaked:

GitHub's RSA key bundled in Cargo has been updated, to ensure systems that haven't interacted with GitHub yet won't connect trusting the leaked key.
The leaked key has been hardcoded as revoked in Cargo, to ensure the key won't be used by Cargo even on systems that still trust the key.

Support for @revoked entries in .ssh/known_hosts (along with a better error message when the unsupported @cert-authority entries are used) is also included in Rust 1.68.2, as that change was a pre-requisite for backporting the hardcoded revocation.

If you cannot upgrade to Rust 1.68.2, we recommend following GitHub's instructions on updating the trusted keys in your system. Note that the keys bundled in Cargo are only used if no trusted key for github.com is found on the system.

Contributors to 1.68.2

Many people came together to create Rust 1.68.2. We couldn't have done it without all of you. Thanks!

Announcing Rust 1.68.1

2023-03-23

The Rust team has published a new point release of Rust, 1.68.1. Rust is a programming language that is empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, you can get 1.68.1 with:

rustup update stable

If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.68.1 on GitHub.

What's in 1.68.1 stable

Rust 1.68.1 stable primarily contains a change to how Rust's CI builds the Windows MSVC compiler, no longer enabling LTO for the Rust code. This led to a miscompilation that the Rust team is debugging, but in the meantime we're reverting the change to enable LTO.

This is currently believed to have no effect on wider usage of ThinLTO. The Rust compiler used an unstable flag as part of the build process to enable ThinLTO despite compiling to a dylib.

There are a few other regression fixes included in the release:

Contributors to 1.68.1

Many people came together to create Rust 1.68.1. We couldn't have done it without all of you. Thanks!

This Week in Rust 487

2023-03-22

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.

Foundation

Newsletters

This Month in Rust OSDev: February 2023 | Rust OSDev

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Research

Miscellaneous

Crate of the Week

This week's crate is Speedy2D, a crate offering cross-platform Hardware-accelerated drawing of shapes, images, and text, with an easy to use API.

Thanks to Aleksey Kladov 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.

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

Updates from the Rust Project

321 pull requests were merged in the last week

Rust Compiler Performance Triage

A mixed week, with some nice wins, but also at least two PR's that were subsequently reverted, such as the upgrade to LLVM 16. We do want to note PR #108944, which cut down on crate metadata, binary sizes, and was an overall win on execution time for many benchmarks.

Triage done by @pnkfelix. Revision range: 00587489..ef03fda3

1 Regressions, 4 Improvements, 11 Mixed; 2 of them in rollups 37 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] RFC: result_ffi_guarantees

Tracking Issues & PRs

[disposition: merge] Initial support for return type notation (RTN)
[disposition: merge] rustdoc: add support for type filters in arguments and generics
[disposition: merge] rustdoc: run more HIR validation to mirror rustc
[disposition: merge] Add a builtin FnPtr trait that is implemented for all function pointers
[disposition: merge] Clarify stability guarantee for lifetimes in enum discriminants

New and Updated RFCs

No New or Updated RFCs were created this week.

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 2023-03-22 - 2023-04-19 🦀

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 generated program is a random sequence of bytes that just happens to take the shape of a seemingly working program by accident. Such is the joy of code that causes UB. You cannot deduce anything from what happens when you execute a program with UB, since that act is by itself meaningless. You need to establish that your program has no UB before making any inference based on what you see the program do after it came out of the compiler.

– Ralf Jung on github

Thanks to bugaevc 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

This Week in Rust 486

2023-03-15

This Week in Rust is openly developed on GitHub. If you find any errors in this week's issue, please submit a PR.

Official

Announcing Rust 1.68.0

Newsletters

This Month in Rust GameDev #43 - February 2023

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Crate of the Week

This week's crate is duplicate, a proc macro crate for easy parametric code duplication.

Thanks to Anton Fetisov 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.

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

Rust Compiler Performance Triage

A fairly mixed week, with several significant improvements and a few significant regressions. On average, this week saw a slight increase in compile times.

Triage done by @simulacrum. Revision range: 8f9e09ac..0058748

4 Regressions, 6 Improvements, 4 Mixed; 2 of them in rollups 39 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 {Arc, Rc}::into_inner
[disposition: merge] rustdoc: add support for type filters in arguments and generics
[disposition: merge] Lint ambiguous glob re-exports

New and Updated RFCs

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-03-15 - 2023-04-12 🦀

Virtual

2023-03-15 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Injecting Rust Hooks into a 1999 game binary (unsafe)
2023-03-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Rust Study/Hack/Hang-out
2023-03-16 | Virtual (Raleigh, NC, US) | Triangle BitDevs
- Rust for Bitcoiners
2023-03-16 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Introduction to WebAssembly (WASM) with Rust and WASMEdge
2023-03-16 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-03-21 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep2
2023-03-21 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful—Using Category Theory to Parse Command-line Options
2023-03-22 | Virtual (Richmond, VA, US) | Rustaceans RVA
- Rustaceans RVA - March Meetup
2023-03-27 | Virtual | Rust Formal Methods Interest Group
- Flux: Ergonomic Verification of Rust Programs with Liquid Types
2023-03-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-03-28 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep3
2023-03-29 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Writing your own rust 'book' with mdBook
2023-04-04 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- Buffalo Rust User Group, First Tuesdays
2023-04-05 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-04-05 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-04-11 | Virtual | Rust Live
- Rust Live: Asynchronous Rust

Europe

2023-03-09 | Basel, CH | Rust Basel
- Rust Meetup #7
2023-03-09 | Delft, NL | Rust Nederland
- Regular track: Embedded Rust
- Student track: Embedded Rust
2023-03-09 | Lyon, FR | Rust Lyon
- Rust Lyon Meetup #2
2023-03-15 | Nürnberg, DE | Rust Nuremberg
- Walk around Embedded World Exhibition
2023-03-15 | Trondheim, NO | Rust Trondheim
- Rust graphics with nannou
2023-03-16 | Paris, FR | OCaml Users in Paris - OUPS
- OUPS Mars 2023: Creusot a prophetic verifier for Rust -- Xavier Denis
2023-03-17 | Stuttgart, DE | Rust Community Stuttgart
- OnSite Meeting
2023-03-28 | Zurich, CH | Rust Zurich
- High performance concurrent data structures in Rust - March Meetup
2023-03-29 | Paris, FR | Rust Paris
- Rust Paris meetup #57
2023-04-04 | Berlin, DE | Berline.rs
- Rust and Tell - Goodbye👋 Edition

North America

2023-03-21 | San Francisco, CA, US | San Francisco Rust Study Group
- Rust Hacking in Person

Asia

2023-04-08 | Kyoto, JP | Kansai Rust
- Demystifying Closures

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 Rust compiler is a thousand unit tests that you don't have to write

– Someone, likely Ian Purton on the Cloak blog

Thanks to Stephan Sokolow 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

Announcing Rust 1.68.0

2023-03-09

The Rust team is happy to announce a new version of Rust, 1.68.0. Rust is a programming language empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, you can get 1.68.0 with:

rustup update stable

If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.68.0 on GitHub.

If you'd like to help us out by testing future releases, you might consider updating locally to use the beta channel (rustup default beta) or the nightly channel (rustup default nightly). Please report any bugs you might come across!

What's in 1.68.0 stable

Cargo's sparse protocol

Cargo's "sparse" registry protocol has been stabilized for reading the index of crates, along with infrastructure at https://index.crates.io/ for those published in the primary crates.io registry. The prior git protocol (which is still the default) clones a repository that indexes all crates available in the registry, but this has started to hit scaling limitations, with noticeable delays while updating that repository. The new protocol should provide a significant performance improvement when accessing crates.io, as it will only download information about the subset of crates that you actually use.

To use the sparse protocol with crates.io, set the environment variable CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse, or edit your .cargo/config.toml file to add:

[registries.crates-io]
protocol = "sparse"

The sparse protocol is currently planned to become the default for crates.io in the 1.70.0 release in a few months. For more information, please see the prior announcement on the Inside Rust Blog, as well as RFC 2789 and the current documentation in the Cargo Book.

Local `Pin` construction

The new pin! macro constructs a Pin<&mut T> from a T expression, anonymously captured in local state. This is often called stack-pinning, but that "stack" could also be the captured state of an async fn or block. This macro is similar to some crates, like tokio::pin!, but the standard library can take advantage of Pin internals and temporary lifetime extension for a more expression-like macro.

/// Runs a future to completion.
fn block_on<F: Future>(future: F) -> F::Output {
    let waker_that_unparks_thread = todo!();
    let mut cx = Context::from_waker(&waker_that_unparks_thread);
    // Pin the future so it can be polled.
    let mut pinned_future = pin!(future);
    loop {
        match pinned_future.as_mut().poll(&mut cx) {
            Poll::Pending => thread::park(),
            Poll::Ready(result) => return result,
        }
    }
}

In this example, the original future will be moved into a temporary local, referenced by the new pinned_future with type Pin<&mut F>, and that pin is subject to the normal borrow checker to make sure it can't outlive that local.

Default `alloc` error handler

When allocation fails in Rust, APIs like Box::new and Vec::push have no way to indicate that failure, so some divergent execution path needs to be taken. When using the std crate, the program will print to stderr and abort. As of Rust 1.68.0, binaries which include std will continue to have this behavior. Binaries which do not include std, only including alloc, will now panic! on allocation failure, which may be further adjusted via a #[panic_handler] if desired.

In the future, it's likely that the behavior for std will also be changed to match that of alloc-only binaries.

Stabilized APIs

These APIs are now stable in const contexts:

VecDeque::new

Other changes

As previously announced, Android platform support in Rust is now targeting NDK r25, which corresponds to a minimum supported API level of 19 (KitKat).

Check out everything that changed in Rust, Cargo, and Clippy.

Contributors to 1.68.0

Many people came together to create Rust 1.68.0. We couldn't have done it without all of you. Thanks!

This Week in Rust 485

2023-03-08

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

Foundation

Rust Nation 2023

Newsletters

Rust Magazine Issue 2 has been released!

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Crate of the Week

This week's crate is man-in-the-middle-proxy, a - surprise! - man in the middle proxy.

Thanks to Emanuele Em 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.

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

Updates from the Rust Project

376 pull requests were merged in the last week

Rust Compiler Performance Triage

A really quiet week with almost all regressions being due to noise in benchmarks that show "bimodality" in codegen that can cause swings in performance from one change to the other. The only true performance change was a two-line change by @nnethercote to remove a redundant function call which led to a 0.3% improvement in performance across roughly 15 benchmarks.

Triage done by @rylev. Revision range: 31f858d9..8f9e09ac

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.0%	[1.2%, 2.8%]	8
Improvements ✅ (primary)	-0.4%	[-0.7%, -0.2%]	7
Improvements ✅ (secondary)	-1.0%	[-1.8%, -0.1%]	31
All ❌✅ (primary)	-0.4%	[-0.7%, -0.2%]	7

7 Regressions, 8 Improvements, 2 Mixed; 7 of them in rollups 35 artifact comparisons made in total

Full report

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: close] RFC - sigil-option-notation

Tracking Issues & PRs

[disposition: merge] Implement tuple<->array convertions via From
[disposition: close] Tracking Issue for Mutex::unlock()
[disposition: close] Tracking issue for Option::contains and Result::contains
[disposition: merge] Remove box_syntax

New and Updated RFCs

No New or Updated RFCs were created this week.

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-03-08 - 2023-04-05 🦀

Virtual

2023-03-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-03-09 | Virtual (Nürnberg, DE) | Rust Nuremberg
- Rust Nürnberg online
2023-03-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-03-14 | Virtual (Italy) | Hinto
- Webinar online | Introduzione a Rust
2023-03-14 | Virtual (Berlin, DE) | Berlin.rs
- Rust Hack and Learn
2023-03-14 | Virtual (Dallas, TX, US) | Dallas Rust
- Second Tuesday
2023-03-14 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep1
2023-03-14 | Virtual (Saarbrücken, DE) | Rust-Saar
- Meetup: 27u16
2023-03-15 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Injecting Rust Hooks into a 1999 game binary (unsafe)
2023-03-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Rust Study/Hack/Hang-out
2023-03-16 | Virtual (Raleigh, NC, US) | Triangle BitDevs
- Rust for Bitcoiners
2023-03-16 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Introduction to WebAssembly (WASM) with Rust and WASMEdge
2023-03-16 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-03-21 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep2
2023-03-21 | Virtual (Washington, DC, US) | Rust DC
- Rust+Tell Lightning Talks
2023-03-22 | Virtual (Richmond, VA, US) | Rustaceans RVA
- Rustaceans RVA - March Meetup
2023-03-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-03-28 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep3
2023-03-29 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Writing your own rust 'book' with mdBook
2023-04-04 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- Buffalo Rust User Group, First Tuesdays
2023-04-05 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-04-05 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup

Europe

2023-03-09 | Basel, CH | Rust Basel
- Rust Meetup #7
2023-03-09 | Delft, NL | Rust Nederland
- Regular track: Embedded Rust
- Student track: Embedded Rust
2023-03-09 | Lyon, FR | Rust Lyon
- Rust Lyon Meetup #2
2023-03-15 | Nürnberg, DE | Rust Nuremberg
- Walk around Embedded World Exhibition
2023-03-15 | Trondheim, NO | Rust Trondheim
- Rust graphics with nannou
2023-03-16 | Paris, FR | OCaml Users in Paris - OUPS
- OUPS Mars 2023: Creusot a prophetic verifier for Rust -- Xavier Denis
2023-03-17 | Stuttgart, DE | Rust Community Stuttgart
- OnSite Meeting
2023-03-28 | Zurich, CH | Rust Zurich
- High performance concurrent data structures in Rust - March Meetup
2023-03-29 | Paris, FR | Rust Paris
- Rust Paris meetup #57

North America

2023-03-09 | Lehi, UT, US | Utah Rust
- Trails, Triumphs, & Travails of Yet-Another-Database-Crate with PJ and Food!

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

(…) as much as i dislike the cargo-geiger concept, the name … kind of works

unsafe is a lot like uranium. it’s just one more metal ore you can process, refine, and machine. it doesn’t combust in atmosphere, it doesn’t corrode or make weird acids. unless you go out of your way to make it dangerous you don’t even have to worry about critical masses. you can work with it pretty normally most of the time

but if you don’t know exactly what it is, what it does, and how to work with it, it will cause mysterious illnesses that only crop up long after you’ve stopped touching it

– Alexander Payne on /r/rust

Thanks to Stephan Sokolow 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

This Week in Rust 484

2023-03-01

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

Official

Keyword Generics Progress Report: February 2023

Newsletters

This Month in Rust GameDev #42 - January 2023

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Crate of the Week

This week's crate is goku, a HTTP load tester.

Thanks to Joaquín Caro 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.

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

Updates from the Rust Project

381 pull requests were merged in the last week

Rust Compiler Performance Triage

Some noisy benchmarks impeded performance review this week. There was a notable improvement to a broad range of primary benchmarks, first from PR #108440, which revised the encodable proc macro to handle the discriminant separately from its fields, and second from PR #108375, which inlined a number of methods that had only a single caller. Both of these PR's were authored by the same contributor; many thanks Zoxc!

Triage done by @pnkfelix. Revision range: 3fee48c1..31f858d9

5 Regressions, 4 Improvements, 6 Mixed; 6 of them in rollups 39 artifact comparisons made in total

Full report

Approved RFCs

Changes to Rust follow the Rust RFC (request for comments) process. These are the RFCs that were approved for implementation this week:

RFC: Move std::net::IpAddr types into core::net.

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: close] Rename {Option, Result}::expect to unwrap_or_panic
[disposition: close] take on bool

Tracking Issues & PRs

[disposition: merge] io: soften ‘at most one write attempt’ requirement in io::Write::write
[disposition: merge] Make unused_allocation lint against Box::new too
[disposition: merge] Properly allow macro expanded format_args invocations to uses captures
[disposition: merge] Add NonZero{I,U}{8,16,32,64,128,size}::{MIN,MAX}
[disposition: merge] allow negative numeric literals in concat!
[disposition: merge] Tracking issue for atomic_mut_ptr
[disposition: merge] Add documentation about the memory layout of Cell
[disposition: merge] Tracking issue for PathBuf::as_mut_os_string and Path::as_mut_os_str
[disposition: merge] Use partial_cmp to implement tuple lt/le/ge/gt

New and Updated RFCs

[new] Create RFC for bundling local images in rustdoc output
[new] Extern types v2
[new] format-dynamic-fill
[new] Add RFC on governance, establishing the Leadership Council
[new] RFC: result_ffi_guarantees

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-03-01 - 2023-03-29 🦀

Virtual

2023-03-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - Michael Baykov on Category Theory & Argument Parsing
2023-03-02 | Virtual (Raleigh, NC, US) | Triangle BitDevs
- Rust for Bitcoiners
2023-03-02 | Virtual (Linz, AT) | Rust Linz
- Rust Meetup Linz - 30th Edition
2023-03-07 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- Buffalo Rust User Group, First Tuesdays
2023-03-07 | Virtual (Santa Clara, CA, US) | UCSC Extension Community
- Programming with Rust
2023-03-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-03-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-03-14 | Virtual (Berlin, DE) | Berlin.rs
- Rust Hack and Learn
2023-03-14 | Virtual (Dallas, TX, US) | Dallas Rust
- Second Tuesday
2023-03-14 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep1
2023-03-15 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Injecting Rust Hooks into a 1999 game binary (unsafe)
2023-03-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Rust Study/Hack/Hang-out
2023-03-16 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Introduction to WebAssembly (WASM) with Rust and WASMEdge
2023-03-16 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-03-21 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep2
2023-03-21 | Virtual (Washington, DC, US) | Rust DC
- Rust+Tell Lightning Talks
2023-03-22 | Virtual (Richmond, VA, US) | Rustaceans RVA
- Rustaceans RVA - March Meetup
2023-03-28 | Virtual (Redmond, WA, US) | Microsoft Reactor Redmond
- Crack code interview problems in Rust: S2 Ep3
2023-03-29 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Writing your own rust 'book' with mdBook

Asia

2023-03-04 | Kyoto, JP | Kansai Rust
- Fn vs FnMut vs FnOnce

Europe

2023-03-01 | Cologne, DE | Rust Cologne
- Rust traits for Fn and profit
2023-03-02 | Barcelona, ES | BcnRust
- 9th BcnRust Meetup: Full Stack
2023-03-02 | Wrocław, PL | Rust Wrocław
- Rust Wrocław Meetup #32
2023-03-07 | Bratislava, SK | Bratislava Rust Meetup Group
- Rust Meetup by Sonalake
2023-03-09 | Basel, CH | Rust Basel
- Rust Meetup #7
2023-03-09 | Delft, NL | Rust Nederland
- Regular track: Embedded Rust
- Student track: Embedded Rust
2023-03-09 | Lyon, FR | Rust Lyon
- Rust Lyon Meetup #2
2023-03-15 | Nürnberg, DE | Rust Nuremberg
- Walk around Embedded World Exhibition
2023-03-17 | Stuttgart, DE | Rust Community Stuttgart
- OnSite Meeting
2023-03-28 | Zurich, CH | Rust Zurich
- High performance concurrent data structures in Rust - March Meetup

North America

2023-03-01 | Austin, TX, US | Rust ATX
- Rust Lunch
2023-03-09 | Lehi, UT, US | Utah Rust
- Trails, Triumphs, & Travails of Yet-Another-Database-Crate with PJ and Food!

Oceania

2023-03-01 | Sydney, NSW, AU | Rust Sydney
- 🦀 Lightning Talks - We are back!

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

You've probably come across unsafe. So "unsafe" is a keyword that sort of unlocks super powers and segfaults.

– Arthur Cohen during FOSDEM '23

Thanks to blonk 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

This Week in Rust 483

2023-02-22

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

RustConf 2023: Call for Proposals

Official

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Research

The Usability of Advanced Type Systems: Rust as a Case Study

Miscellaneous

Crate of the Week

This week's crate is Darkbird, a high-concurrency real-time in-memory database.

Thanks to DanyalMh 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.

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

Updates from the Rust Project

396 pull requests were merged in the last week

Rust Compiler Performance Triage

Overall a fairly positive week, with few noise-related regressions or improvements and many benchmarks showing significant improvements. The one large regression is limited to documentation builds and has at least a partial fix already planned.

Other wins this week include an average improvement of around 1% in maximum memory usage of optimized builds, and a 2% average reduction in compiled binary sizes. These are fairly significant wins for these metrics.

Triage done by @simulacrum. Revision range: 9bb6e60..3fee48c1

3 Regressions, 3 Improvements, 3 Mixed; 2 of them in rollups 45 artifact comparisons made in total

Full report

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] rustdoc: search by macro when query ends with !
[disposition: merge] Stabilize rustdoc --test-run-directory
[disposition: merge] Treat str as containing [u8] for auto trait purposes

New and Updated RFCs

[new] Stabilize may_dangle
[new] Add a [lints] table to Cargo.toml

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-02-22 - 2023-03-22 🦀

Virtual

2023-02-23 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- Tock, a Rust based Embedded Operating System
2023-02-23 | Virtual (Kassel, DE) | Java User Group Hessen
- Eine Einführung in Rust (Stefan Baumgartner)
2023-02-23 | Virtual (México City, MX) | Rust MX
- Rust: ¿por qué es una opción adecuada para implantar Blockchain?
2023-02-24 | Virtual (Tunis, TN) | Rust Meetup Tunisia
- Rust Meetup Tunisia - Volume I, Number II
2023-02-28 | Virtual (Berlin, DE) | Open Tech School Berlin
- Rust Hack and Learn
2023-02-28 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Rust Nation - What we learnt
2023-02-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-02-28 | Virtual (Munich, DE) | Rust Munich
- Rust Munich 2023 / 1 - hybrid
2023-03-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - Michael Baykov on Category Theory & Argument Parsing
2023-03-02 | Virtual (Linz, AT) | Rust Linz
- Rust Meetup Linz - 30th Edition
2023-03-07 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- First Tuesdays
2023-03-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-03-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-03-14 | Virtual (Berlin, DE) | Berlin.rs
- Rust Hack and Learn
2023-03-15 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Injecting Rust Hooks into a 1999 game binary (unsafe)
2023-03-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Rust Study/Hack/Hang-out
2023-03-21 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful

Asia

2023-03-04 | Kyoto, JP | Kansai Rust
- Fn vs FnMut vs FnOnce

Europe

2023-02-23 | Bordeaux, FR | DedoTalk
- #1 DedoTalk 🎙️ : Rust pour un développeur Python
2023-02-23 | Copenhagen, DK | Copenhagen Rust Community
- Rust metup #33
2023-02-23 | Vienna, AT | Rust Vienna
- Rust Meetup Revived with an Exciting Exploration of Ownership!
2023-02-28 | Munich, DE + Virtual | Rust Munich
- Rust Munich 2023 / 1 - hybrid
2023-02-28 | Nijmegen, NL | Rust Nederland
- Regular track: Rust at RU
- Student track: Rust at RU
2023-03-01 | Cologne, DE | Rust Cologne
- Rust traits for Fn and profit
2023-03-02 | Barcelona, ES | BcnRust
- 9th BcnRust Meetup: Full Stack
2023-03-02 | Wrocław, PL | Rust Wrocław
- Rust Wrocław Meetup #32
2023-03-07 | Bratislava, SK | Bratislava Rust Meetup Group
- Rust Meetup by Sonalake
2023-03-09 | Basel, CH | Rust Basel
- Rust Meetup #7
2023-03-09 | Delft, NL | Rust Nederland
- Regular track: Embedded Rust
- Student track: Embedded Rust
2023-03-09 | Lyon, FR | Rust Lyon
- Rust Lyon Meetup #2
2023-03-15 | Nürnberg, DE | Rust Nuremberg
- Walk around Embedded World Exhibition

North America

2023-02-23 | Mountain View, CA, US | Mountain View Rust Study Group
- Rust Meetup at Hacker Dojo
2023-03-01 | Austin, TX, US | Rust ATX
- Rust Lunch
2023-03-09 | Lehi, UT, US | Utah Rust
- Trails, Triumphs, & Travails of Yet-Another-Database-Crate with PJ and Food!

Oceania

2023-02-23 | Brisbane, QLD, AU | Rust Brisbane
- February Meetup
2023-02-28 | Canberra, ACT, AU | Canberra Rust User Group
- February Meetup
2023-03-01 | Sydney, NSW, AU | Rust Sydney
- 🦀 Lightning Talks - We are back!

South America

2023-02-22 | Montevideo, UY | Rust Meetup Uruguay
- Hands on: Lifetimes

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

It’s enjoyable to write Rust, which is maybe kind of weird to say, but it’s just the language is fantastic. It’s fun. You feel like a magician, and that never happens in other languages.

– Parker Timmerman cited in a TechnologyReview article

Thanks to robin 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

This Week in Rust 482

2023-02-15

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

Newsletters

Rust Nigeria #14

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

[video] Build and deploy a Wasm smart contract with Rust-based language
[video] Write better parsers with nom_supreme

Miscellaneous

[video] From cargo to crates.io and back again
[video] Functional correctness with refinement types for Rust
[audio] Rust ABI with Aurimas Blažulionis
[audio] What's New in Rust 1.65, 1.66, and 1.67
[audio] Open Source Security Podcast: A lesson in Rust from Carol Nichols

Crate of the Week

This week's crate is bkmr, a fast CLI bookmark manager and launcher.

Thanks to sysid 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.

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

Updates from the Rust Project

387 pull requests were merged in the last week

Rust Compiler Performance Triage

Overall a good week for performance with 77 real world crates benchmarks showing an average of nearly 1% performance improvement. Unfortunately, the largest regressions are not yet fully understood and require additional investigation. Of particular interest were some large improvements in doc builds due to storing additional metadata. However, this change might cause some crates to compile slightly slower in incremental check builds, but this is still being investigated.

Triage done by @rylev. Revision range: e4dd9edb..9bb6e60

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	1.4%	[0.4%, 11.0%]	13
Regressions ❌ (secondary)	0.8%	[0.2%, 1.6%]	4
Improvements ✅ (primary)	-1.4%	[-7.9%, -0.3%]	64
Improvements ✅ (secondary)	-2.1%	[-5.6%, -0.3%]	73
All ❌✅ (primary)	-0.9%	[-7.9%, 11.0%]	77

3 Regressions, 4 Improvements, 9 Mixed; 4 of them in rollups 46 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] Drop support for FreeBSD 10 and 11 from std
[disposition: merge] Stabilize cmpxchg16b_target_feature

New and Updated RFCs

No New or Updated RFCs were created this week.

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-02-15 - 2023-03-15 🦀

Virtual

2023-02-15 | Virtual | MongoDB
- Write a Microservice With Rust and MongoDB
2023-02-15 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US; São Paulo, BR) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco and Microsoft Reactor São Paulo
- Primeros pasos con Rust: QA y horas de comunidad | San Francisco Mirror | New York Mirror | São Paulo Mirror
2023-02-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Show & Tell: Rust state machines in a file processor
2023-02-16 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-02-21 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful
2023-02-23 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- Tock, a Rust based Embedded Operating System
2023-02-23 | Virtual (Kassel, DE) | Java User Group Hessen
- Eine Einführung in Rust (Stefan Baumgartner)
2023-02-23 | Virtual (México City, MX) | Rust MX
- Rust: ¿por qué es una opción adecuada para implantar Blockchain?
2023-02-24 | Virtual (Tunis, TN) | Rust Meetup Tunisia
- Rust Meetup Tunisia - Volume I, Number II
2023-02-28 | Virtual (Berlin, DE) | Open Tech School Berlin
- Rust Hack and Learn
2023-02-28 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Rust Nation - What we learnt
2023-02-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-02-28 | Virtual (Munich, DE) | Rust Munich
- Rust Munich 2023 / 1 - hybrid
2023-03-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-03-02 | Virtual (Linz, AT) | Rust Linz
- Rust Meetup Linz - 30th Edition
2023-03-07 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- First Tuesdays
2023-03-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-03-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-03-14 | Virtual (Berlin, DE) | Berlin.rs
- Rust Hack and Learn
2023-03-15 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Injecting Rust Hooks into a 1999 game binary (unsafe)

Asia

2023-02-20 | Tel Aviv, IL | Rust TLV
- February Edition - Redis and BioCatch talking Rust!
2023-03-04 | Kyoto, JP | Kansai Rust
- Fn vs FnMut vs FnOnce

Europe

2023-02-15 | London, UK | Rust London User Group
- Rust Nation Pre-Conference Reception with The Rust Foundation
2023-02-15 | Trondheim, NO | Rust Trondheim
- Rust New Year's Resolution Bug Hunt
2023-02-16, 2023-02-17 | London, UK | Rust Nation UK
- Rust Nation '23
2023-02-18 | London, UK | Rust London User Group
- Post-Conference Rust in Enterprise Brunch Hosted at Red Badger
2023-02-21 | Paris, FR | Rust Paris
- Rust Paris meetup #56
2023-02-21 | Zurich, CH | Rust Zurich
- Practical Cryptography - February Meetup (Registration opens 7 Feb 2023)
2023-02-23 | Bordeaux, FR | DedoTalk
- #1 DedoTalk 🎙️ : Rust pour un développeur Python
2023-02-23 | Copenhagen, DK | Copenhagen Rust Community
- Rust metup #33
2023-02-23 | Vienna, AT | Rust Vienna
- Rust Meetup Revived with an Exciting Exploration of Ownership!
2023-02-28 | Munich, DE + Virtual | Rust Munich
- Rust Munich 2023 / 1 - hybrid
2023-02-28 | Nijmegen, NL | Rust Nederland
- Regular track: Rust at RU
- Student track: Rust at RU
2023-03-09 | Basel, CH | Rust Basel
- Rust Meetup #7
2023-03-09 | Delft, NL | Rust Nederland
- Regular track: Embedded Rust
- Student track: Embedded Rust
2023-03-15 | Nürnberg, DE | Rust Nuremberg
- Walk around Embedded World Exhibition

North America

2023-02-21 | San Francisco, CA, US | San Francisco Rust Study Group
- Rust Hacking in Person
2023-02-23 | Mountain View, CA, US | Mountain View Rust Study Group
- Rust Study Group at Hacker Dojo
2023-03-01 | Austin, TX, US | Rust ATX
- Rust Lunch
2023-03-09 | Lehi, UT, US | Utah Rust
- Upcoming Event

Oceania

2023-02-23 | Brisbane, QLD, AU | Rust Brisbane
- February Meetup
2023-02-28 | Canberra, ACT, AU | Canberra Rust User Group
- February Meetup
2023-03-01 | Sydney, NSW, AU | Rust Sydney
- 🦀 Lightning Talks - We are back!

South America

2023-02-22 | Montevideo, UY | Rust Meetup Uruguay
- Hands on: Lifetimes

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

All the pro C/C++ arguments seem to come down to "Good drivers don’t need seat belts because they don’t get in accidents"

– otwkme on /r/rust

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

Test 1. 2

2023-02-14

Testing the post feature

Announcing Rust 1.67.1

2023-02-09

The Rust team has published a new point release of Rust, 1.67.1. Rust is a programming language that is empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, you can get 1.67.1 with:

rustup update stable

If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.67.1 on GitHub.

What's in 1.67.1 stable

Rust 1.67.1 fixes a regression for projects that link to thin archives (.a files that reference external .o objects). The new archive writer in 1.67.0 could not read thin archives as inputs, leading to the error "Unsupported archive identifier." The compiler now uses LLVM's archive writer again, until that format is supported in the new code.

Additionally, the clippy style lint uninlined_format_args is temporarily downgraded to pedantic -- allowed by default. While the compiler has supported this format since Rust 1.58, rust-analyzer does not support it yet, so it's not necessarily good to use that style everywhere possible.

The final change is a soundness fix in Rust's own bootstrap code. This had no known problematic uses, but it did raise an error when bootstrap was compiled with 1.67 itself, rather than the prior 1.66 release as usual.

Contributors to 1.67.1

Many people came together to create Rust 1.67.1. We couldn't have done it without all of you. Thanks!

This Week in Rust 481

2023-02-08

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

Official

Announcing Rustup 1.25.2

Foundation

Member Spotlight: AdaCore

FOSDEM 2023

[video] Building an actor library for Quickwit's indexing pipeline
[video] Building a distributed search engine with tantivy
[video] Aurae: Distributed Runtime
[video] BastionLab, a Rust open-source privacy framework for confidential data science collaboration
[video] Neovim and rust-analyzer are best friends
[video] A Rusty CHERI - The path to hardware capabilities in Rust
[video] Slint: Are we GUI yet?
[video] Rust API Design Learnings
[video] A deep dive inside the Rust frontend for GCC
[video] Merging process of the rust compiler
[video] Let's write Snake game!
[video] Glidesort
[video] How Pydantic V2 leverages Rust's Superpowers
[video] Scalable graph algorithms in Rust (and Python)
[video] Using Rust for your network management tools!
[video] Backward and forward compatibility for security features
[video] atuin: magical shell history with Rust
[video] A Rust-Based, modular Unikernel for MicroVMs

Newsletters

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Crate of the Week

This week's crate is envious, a serde-based deserializer from environment variables.

Thanks to musicmatze 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.

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

Updates from the Rust Project

350 pull requests were merged in the last week

Rust Compiler Performance Triage

Much noise in benchmarks this week, which makes it hard to tell what the real improvements were and what they were due to. A query cache change (PR #107667) is part of the story. In addition, much improvement was reaped from the change to not deaggregate MIR (PR #107267). Finally, microoptimizing fold_ty (PR #107627) yielded a small improvement to a broad set of benchmarks.

Triage done by @pnkfelix. Revision range: a64ef7d0..e4dd9edb

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	2.4%	[0.3%, 18.8%]	18
Regressions ❌ (secondary)	1.8%	[0.2%, 4.1%]	21
Improvements ✅ (primary)	-1.0%	[-3.2%, -0.3%]	88
Improvements ✅ (secondary)	-4.0%	[-13.1%, -0.1%]	47
All ❌✅ (primary)	-0.4%	[-3.2%, 18.8%]	106

3 Regressions, 3 Improvements, 8 Mixed; 3 of them in rollups 41 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] rework min_choice algorithm of member constraints
[disposition: merge] fix: Unexpected trait bound not satisfied in HRTB and Associated Type
[disposition: merge] Stabilize feature cstr_from_bytes_until_nul
[disposition: merge] rustdoc: remove inconsistently-present sidebar tooltips
[disposition: merge] Relax ordering rules for asm! operands

New and Updated RFCs

[new] recommended-bin-crates field in Cargo.toml
[new] Ref-wrapping

Call for Testing

No RFCs issued a call for testing this week.

Upcoming Events

Rusty Events between 2023-02-08 - 2023-03-08 🦀

Virtual

2023-02-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-02-08 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust: QA y horas de comunidad | New York Mirror | San Francisco Mirror
2023-02-09 | Virtual (Nürnberg, DE) | Rust Nuremberg
- Rust Nürnberg online
2023-02-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-02-13 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Escritura de pruebas automatizadas | New York Mirror | San Francisco Mirror
2023-02-14 | Virtual (Berlin, DE) | OpenTechSchool Berlin
- Rust Hack and Learn
2023-02-14 | Virtual (Dallas, TX, US) | Dallas Rust
- Second Tuesday
2023-02-14 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Creamos un programa de ToDos en la línea de comandos | San Francisco Mirror | New York Mirror
2023-02-14 | Virtual (Saarbrücken, DE) | Rust-Saar
- Meetup: 26u16
2023-02-15 | Virtual | MongoDB
- Write a Microservice With Rust and MongoDB
2023-02-15 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US; São Paulo, BR) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco and Microsoft Reactor São Paulo
- Primeros pasos con Rust: QA y horas de comunidad | San Francisco Mirror | New York Mirror | São Paulo Mirror
2023-02-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Show & Tell: Rust state machines in a file processor
2023-02-16 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-02-21 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful
2023-02-23 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- Tock, a Rust based Embedded Operating System
2023-02-23 | Virtual (Kassel, DE) | Java User Group Hessen
- Eine Einführung in Rust (Stefan Baumgartner)
2023-02-23 | Virtual (México City, MX) | Rust MX
- Rust: ¿por qué es una opción adecuada para implantar Blockchain?
2023-02-28 | Virtual (Berlin, DE) | Open Tech School Berlin
- Rust Hack and Learn
2023-02-28 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- Rust Nation - What we learnt
2023-02-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-02-28 | Virtual (Munich, DE) | Rust Munich
- Rust Munich 2023 / 1 - hybrid
2023-03-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-03-02 | Virtual (Linz, AT) | Rust Linz
- Rust Meetup Linz - 30th Edition
2023-03-07 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- First Tuesdays
2023-03-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup

Asia

2023-02-14 | Tokyo, JP | Tokyo Rust Meetup
- Crafting Command Line Tools With Rust
2023-02-20 | Tel Aviv, IL | Rust TLV
- February Edition - Redis and BioCatch talking Rust!

Europe

2023-02-09 | Lille, FR | Rust Lille
- Rust Lille #2
2023-02-15 | London, UK | Rust London User Group
- Rust Nation Pre-Conference Reception with The Rust Foundation
2023-02-15 | Trondheim, NO | Rust Trondheim
- Rust New Year's Resolution Bug Hunt
2023-02-16 | Bordeaux, FR | DedoTalk
- #1 DedoTalk 🎙️ : Rust pour un développeur Python
2023-02-16, 2023-02-17 | London, UK | Rust Nation UK
- Rust Nation '23
2023-02-18 | London, UK | Rust London User Group
- Post-Conference Rust in Enterprise Brunch Hosted at Red Badger
2023-02-21 | Paris, FR | Rust Paris
- Rust Paris meetup #56
2023-02-21 | Zurich, CH | Rust Zurich
- Practical Cryptography - February Meetup (Registration opens 7 Feb 2023)
2023-02-23 | Copenhagen, DK | Copenhagen Rust Community
- Rust metup #33
2023-02-23 | Vienna, AT | Rust Vienna
- Rust Meetup Revived with an Exciting Exploration of Ownership!
2023-02-28 | Munich, DE + Virtual | Rust Munich
- Rust Munich 2023 / 1 - hybrid

North America

2023-02-09 | Mountain View, CA, US | Mountain View Rust Study Group
- Rust Study Group at Hacker Dojo
2023-02-09 | New York, NY, US | Rust NYC
- A Night of Interop: Rust in React Native & Rust in Golang (two talks)
2023-02-13 | Minneapolis, MN, US | Minneapolis Rust Meetup
- Happy Hour and Beginner Embedded Rust Hacking Session (#3!)
2023-02-21 | San Francisco, CA, US | San Francisco Rust Study Group
- Rust Hacking in Person
2023-02-23 | Lehi, UT, US | Utah Rust
- Upcoming Event

Oceania

2023-02-23 | Brisbane, QLD, AU | Rust Brisbane
- February Meetup
2023-02-28 | Canberra, ACT, AU | Canberra Rust User Group
- February Meetup
2023-03-01 | Sydney, NSW, AU | Rust Sydney
- 🦀 Lightning Talks - We are back!

South America

2023-02-22 | Montevideo, UY | Rust Meetup Uruguay
- Hands on: Lifetimes

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

It's been 7.5 years since #27060 was reported, but the problem is finally fixed for good. :‍)

– Ralf Jung on github

Thanks to scottmcm 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

This Week in Rust 480

2023-02-01

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

Official

Foundation

Rust Foundation Annual Report 2022

Newsletters

This Month in Rust GameDev #41 - December 2022

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Rust's Ugly Syntax
[video] Rust's Witchcraft
[DE] CodeSandbox: Nun auch für die Rust-Entwicklung

Crate of the Week

This week's crate is symphonia, a collection of pure-Rust audio decoders for many common formats.

Thanks to Kornel 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.

diesel - Generate matching SQL types for Mysql enums

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

Updates from the Rust Project

377 pull requests were merged in the last week

Rust Compiler Performance Triage

Overall a positive week, with relatively few regressions overall and a number of improvements.

Triage done by @simulacrum. Revision range: c8e6a9e..a64ef7d

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	0.3%	[0.3%, 0.3%]	1
Improvements ✅ (primary)	-0.8%	[-2.0%, -0.2%]	27
Improvements ✅ (secondary)	-0.9%	[-1.9%, -0.5%]	11
All ❌✅ (primary)	-0.8%	[-2.0%, 0.6%]	28

2 Regressions, 4 Improvements, 6 Mixed; 2 of them in rollups 44 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:

Create an Operational Semantics Team

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] Stabilize feature cstr_from_bytes_until_nul
[disposition: merge] Support true and false as boolean flag params
[disposition: merge] Implement AsFd and AsRawFd for Rc
[disposition: merge] rustdoc: compute maximum Levenshtein distance based on the query

New and Updated RFCs

[new] Permissions
[new] Add text for the CFG OS Version RFC

Call for Testing

Feature: Help test Cargo's new index protocol

Upcoming Events

Rusty Events between 2023-02-01 - 2023-03-01 🦀

Virtual

2023-02-01 | Virtual (Cardiff, UK) | Rust and C++ Cardiff
- New Year Virtual Social + Share
2023-02-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing
2023-02-01 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Reactor New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust: QA y horas de comunidad | New York Mirror | San Francisco Mirror
2023-02-01 | Virtual (Stuttgart, DE) | Rust Community Stuttgart
- Rust-Meetup
2023-02-06 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Reactor New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Implementación de tipos y rasgos genéricos | New York Mirror | San Francisco Mirror
2023-02-07 | Virtual (Beijing, CN) | WebAssembly and Rust Meetup (Rustlang)
- Monthly WasmEdge Community Meeting, a CNCF sandbox WebAssembly runtime
2023-02-07 | Virtual (Buffalo, NY, US) | Buffalo Rust Meetup
- Buffalo Rust User Group, First Tuesdays
2023-02-07 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Reactor New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Módulos, paquetes y contenedores de terceros | New York Mirror | San Francisco Mirror
2023-02-08 | Virtual (Boulder, CO, US) | Boulder Elixir and Rust
- Monthly Meetup
2023-02-08 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust: QA y horas de comunidad | New York Mirror | San Francisco Mirror
2023-02-09 | Virtual (Nürnberg, DE) | Rust Nuremberg
- Rust Nürnberg online
2023-02-11 | Virtual | Rust GameDev
- Rust GameDev Monthly Meetup
2023-02-13 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Escritura de pruebas automatizadas | New York Mirror | San Francisco Mirror
2023-02-14 | Virtual (Berlin, DE) | OpenTechSchool Berlin
- Rust Hack and Learn
2023-02-14 | Virtual (Dallas, TX, US) | Dallas Rust
- Second Tuesday
2023-02-14 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco
- Primeros pasos con Rust - Creamos un programa de ToDos en la línea de comandos | San Francisco Mirror | New York Mirror
2023-02-14 | Virtual (Saarbrücken, DE) | Rust-Saar
- Meetup: 26u16
2023-02-15 | Virtual (Redmond, WA, US; New York, NY, US; San Francisco, CA, US; São Paulo, BR) | Microsoft Reactor Redmond and Microsoft Rector New York and Microsoft Reactor San Francisco and Microsoft Reactor São Paulo
- Primeros pasos con Rust: QA y horas de comunidad | San Francisco Mirror | New York Mirror | São Paulo Mirror
2023-02-15 | Virtual (Vancouver, BC, CA) | Vancouver Rust
- Rust Study/Hack/Hang-out
2023-02-21 | Virtual (Washington, DC, US) | Rust DC
- Mid-month Rustful
2023-02-23 | Virtual (Charlottesville, VA, US) | Charlottesville Rust Meetup
- Tock, a Rust based Embedded Operating System
2023-02-23 | Virtual (Kassel, DE) | Java User Group Hessen
- Eine Einführung in Rust (Stefan Baumgartner)
2023-02-28 | Virtual (Berlin, DE) | Open Tech School Berlin
- Rust Hack and Learn
2023-02-28 | Virtual (Dallas, TX, US) | Dallas Rust
- Last Tuesday
2023-03-01 | Virtual (Indianapolis, IN, US) | Indy Rust
- Indy.rs - with Social Distancing

Asia

2023-02-01 | Kyoto, JP | Kansai Rust
- Rust talk: How to implement Iterator on tuples... kind of
2023-02-20 | Tel Aviv, IL | Rust TLV
- February Edition - Redis and BioCatch talking Rust!

Europe

2023-02-02 | Berlin, DE | Prenzlauer Berg Software Engineers
- PBerg engineers - inaugural meetup; Lukas: Serverless APIs using Rust and Azure functions (Fee)
2023-02-02 | Hamburg, DE | Rust Meetup Hamburg
- Rust Hack & Learn February 2023
2023-02-02 | Lyon, FR | Rust Lyon
- Rust Lyon meetup #01
2023-02-04 | Brussels, BE | FOSDEM
- FOSDEM 2023 Conference: Rust devroom
2023-02-09 | Lille, FR | Rust Lille
- Rust Lille #2
2023-02-15 | London, UK | Rust London User Group
- Rust Nation Pre-Conference Reception with The Rust Foundation
2023-02-15 | Trondheim, NO | Rust Trondheim
- Rust New Year's Resolution Bug Hunt
2023-02-16, 2023-02-17 | London, UK | Rust Nation UK
- Rust Nation '23
2023-02-18 | London, UK | Rust London User Group
- Post-Conference Rust in Enterprise Brunch Hosted at Red Badger
2023-02-21 | Zurich, CH | Rust Zurich
- Practical Cryptography - February Meetup (Registration opens 7 Feb 2023)
2023-02-23 | Copenhagen, DK | Copenhagen Rust Community
- Rust metup #33

North America

2023-02-09 | Mountain View, CA, US | Mountain View Rust Study Group
- Rust Study Group at Hacker Dojo
2023-02-09 | New York, NY, US | Rust NYC
- A Night of Interop: Rust in React Native & Rust in Golang (two talks)
2023-02-13 | Minneapolis, MN, US | Minneapolis Rust Meetup
- Happy Hour and Beginner Embedded Rust Hacking Session (#3!)
2023-02-21 | San Francisco, CA, US | San Francisco Rust Study Group
- Rust Hacking in Person
2023-02-23 | Lehi, UT, US | Utah Rust
- Upcoming Event

Oceania

2023-02-28 | Canberra, ACT, AU | Canberra Rust User Group
- February Meetup
2023-03-01 | Sydney, NSW, AU | Rust Sydney
- 🦀 Lightning Talks - We are back!

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

Compilers are an error reporting tool with a code generation side-gig.

– Esteban Küber on Hacker News

Thanks to Stefan Majewsky 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

Announcing Rustup 1.25.2

2023-02-01

The rustup working group is announcing the release of rustup version 1.25.2. Rustup is the recommended tool to install Rust, a programming language that is empowering everyone to build reliable and efficient software.

If you have a previous version of rustup installed, getting rustup 1.25.2 is as easy as stopping any programs which may be using Rustup (e.g. closing your IDE) and running:

rustup self update

Rustup will also automatically update itself at the end of a normal toolchain update:

rustup update

If you don't have it already, you can get rustup from the appropriate page on our website.

What's new in rustup 1.25.2

This version of rustup fixes a warning incorrectly saying that signature verification failed for Rust releases. The warning was due to a dependency of Rustup including a time-based check preventing the use of SHA-1 from February 1st, 2023 onwards.

Unfortunately Rust's release signing key uses SHA-1 to sign its subkeys, which resulted in all signatures being marked as invalid. Rustup 1.25.2 temporarily fixes the problem by allowing again the use of SHA-1.

Why is signature verification failure only a warning?

Signature verification is currently an experimental and incomplete feature included in rustup, as it's still missing crucial features like key rotation. Until the feature is complete and ready for use, its outcomes are only displayed as warnings without a way to turn them into errors.

This is done to avoid potentially breaking installations of rustup. Signature verification will error out on failure only after the design and implementation of the feature will be finished.

Thanks

Thanks again to all the contributors who made rustup 1.25.2 possible!

Daniel Silverstone (kinnison)
Pietro Albini (pietroalbini)

Announcing Rust 1.67.0

2023-01-26

The Rust team is happy to announce a new version of Rust, 1.67.0. Rust is a programming language empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, you can get 1.67.0 with:

rustup update stable

If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.67.0 on GitHub.

What's in 1.67.0 stable

`#[must_use]` effective on `async fn`

async functions annotated with #[must_use] now apply that attribute to the output of the returned impl Future. The Future trait itself is already annotated with #[must_use], so all types implementing Future are automatically #[must_use], which meant that previously there was no way to indicate that the output of the Future is itself significant and should be used in some way.

With 1.67, the compiler will now warn if the output isn't used in some way.

#[must_use]
async fn bar() -> u32 { 0 }

async fn caller() {
    bar().await;
}

warning: unused output of future returned by `bar` that must be used
 --> src/lib.rs:5:5
  |
5 |     bar().await;
  |     ^^^^^^^^^^^
  |
  = note: `#[warn(unused_must_use)]` on by default

`std::sync::mpsc` implementation updated

Rust's standard library has had a multi-producer, single-consumer channel since before 1.0, but in this release the implementation is switched out to be based on crossbeam-channel. This release contains no API changes, but the new implementation fixes a number of bugs and improves the performance and maintainability of the implementation.

Users should not notice any significant changes in behavior as of this release.

Stabilized APIs

These APIs are now stable in const contexts:

Check out everything that changed in Rust, Cargo, and Clippy.

Contributors to 1.67.0

Many people came together to create Rust 1.67.0. We couldn't have done it without all of you. Thanks!

Officially announcing the types team

2023-01-20

Oh hey, it's another new team announcement. But I will admit: if you follow the RFCs repository, the Rust zulip, or were particularly observant on the GATs stabilization announcement post, then this might not be a surprise for you. In fact, this "new" team was officially established at the end of May last year.

There are a few reasons why we're sharing this post now (as opposed to months before or...never). First, the team finished a three day in-person/hybrid meetup at the beginning of December and we'd like to share the purpose and outcomes of that meeting. Second, posting this announcement now is just around 7 months of activity and we'd love to share what we've accomplished within this time. Lastly, as we enter into the new year of 2023, it's a great time to share a bit of where we expect to head in this year and beyond.

Background - How did we get here?

Rust has grown significantly in the last several years, in many metrics: users, contributors, features, tooling, documentation, and more. As it has grown, the list of things people want to do with it has grown just as quickly. On top of powerful and ergonomic features, the demand for powerful tools such as IDEs or learning tools for the language has become more and more apparent. New compilers (frontend and backend) are being written. And, to top it off, we want Rust to continue to maintain one of its core design principles: safety.

All of these points highlights some key needs: to be able to know how the Rust language should work, to be able to extend the language and compiler with new features in a relatively painless way, to be able to hook into the compiler and be able to query important information about programs, and finally to be able to maintain the language and compiler in an amenable and robust way. Over the years, considerable effort has been put into these needs, but we haven't quite achieved these key requirements.

To extend a little, and put some numbers to paper, there are currently around 220 open tracking issues for language, compiler, or types features that have been accepted but are not completely implemented, of which about half are at least 3 years old and many are several years older than that. Many of these tracking issues have been open for so long not solely because of bandwidth, but because working on these features is hard, in large part because putting the relevant semantics in context of the larger language properly is hard; it's not easy for anyone to take a look at them and know what needs to be done to finish them. It's clear that we still need better foundations for making changes to the language and compiler.

Another number that might shock you: there are currently 62 open unsoundness issues. This sounds much scarier than it really is: nearly all of these are edges of the compiler and language that have been found by people who specifically poke and prod to find them; in practice these will not pop up in the programs you write. Nevertheless, these are edges we want to iron out.

The Types Team

Moving forward, let's talk about a smaller subset of Rust rather than the entire language and compiler. Specifically, the parts relevant here include the type checker - loosely, defining the semantics and implementation of how variables are assigned their type, trait solving - deciding what traits are defined for which types, and borrow checking - proving that Rust's ownership model always holds. All of these can be thought of cohesively as the "type system".

As of RFC 3254, the above subset of the Rust language and compiler are under the purview of the types team. So, what exactly does this entail?

First, since around 2018, there existed the "traits working group", which had the primary goal of creating a performant and extensible definition and implementation of Rust's trait system (including the Chalk trait-solving library). As time progressed, and particularly in the latter half of 2021 into 2022, the working group's influence and responsibility naturally expanded to the type checker and borrow checker too - they are actually strongly linked and its often hard to disentangle the trait solver from the other two. So, in some ways, the types team essentially subsumes the former traits working group.

Another relevant working group is the polonius working group, which primarily works on the design and implementation of the Polonius borrow-checking library. While the working group itself will remain, it is now also under the purview of the types team.

Now, although the traits working group was essentially folded into the types team, the creation of a team has some benefits. First, like the style team (and many other teams), the types team is not a top level team. It actually, currently uniquely, has two parent teams: the lang and compiler teams. Both teams have decided to delegate decision-making authority covering the type system.

The language team has delegated the part of the design of type system. However, importantly, this design covers less of the "feel" of the features of type system and more of how it "works", with the expectation that the types team will advise and bring concerns about new language extensions where required. (This division is not strongly defined, but the expectation is generally to err on the side of more caution). The compiler team, on the other hand, has delegated the responsibility of defining and maintaining the implementation of the trait system.

One particular responsibility that has traditionally been shared between the language and compiler teams is the assessment and fixing of soundness bugs in the language related to the type system. These often arise from implementation-defined language semantics and have in the past required synchronization and input from both lang and compiler teams. In the majority of cases, the types team now has the authority to assess and implement fixes without the direct input from either parent team. This applies, importantly, for fixes that are technically backwards-incompatible. While fixing safety holes is not covered under Rust's backwards compatibility guarantees, these decisions are not taken lightly and generally require team signoff and are assessed for potential ecosystem breakage with crater. However, this can now be done under one team rather than requiring the coordination of two separate teams, which makes closing these soundness holes easier (I will discuss this more later.)

Formalizing the Rust type system

As mentioned above, a nearly essential element of the growing Rust language is to know how it should work (and to have this well documented). There are relatively recent efforts pushing for a Rust specification (like Ferrocene or this open RFC), but it would be hugely beneficial to have a formalized definition of the type system, regardless of its potential integration into a more general specification. In fact the existence of a formalization would allow a better assessment of potential new features or soundness holes, without the subtle intricacies of the rest of the compiler.

As far back as 2015, not long after the release of Rust 1.0, an experimental Rust trait solver called Chalk began to be written. The core idea of Chalk is to translate the surface syntax and ideas of the Rust trait system (e.g. traits, impls, where clauses) into a set of logic rules that can be solved using a Prolog-like solver. Then, once this set of logic and solving reaches parity with the trait solver within the compiler itself, the plan was to simply replace the existing solver. In the meantime (and continuing forward), this new solver could be used by other tools, such as rust-analyzer, where it is used today.

Now, given Chalk's age and the promises it had been hoped to be able to deliver on, you might be tempted to ask the question "Chalk, when?" - and plenty have. However, we've learned over the years that Chalk is likely not the correct long-term solution for Rust, for a few reasons. First, as mentioned a few times in this post, the trait solver is only but a part of a larger type system; and modeling how the entire type system fits together gives a more complete picture of its details than trying to model the parts separately. Second, the needs of the compiler are quite different than the needs of a formalization: the compiler needs performant code with the ability to track information required for powerful diagnostics; a good formalization is one that is not only complete, but also easy to maintain, read, and understand. Over the years, Chalk has tried to have both and it has so far ended up with neither.

So, what are the plans going forward? Well, first the types team has begun working on a formalization of the Rust typesystem, currently coined a-mir-formality. An initial experimental phase was written using PLT redex, but a Rust port is in-progress. There's lot to do still (including modeling more of the trait system, writing an RFC, and moving it into the rust-lang org), but it's already showing great promise.

Second, we've begun an initiative for writing a new trait solver in-tree. This new trait solver is more limited in scope than a-mir-formality (i.e. not intending to encompass the entire type system). In many ways, it's expected to be quite similar to Chalk, but leverage bits and pieces of the existing compiler and trait solver in order to make the transition as painless as possible. We do expect it to be pulled out-of-tree at some point, so it's being written to be as modular as possible. During our types team meetup earlier this month, we were able to hash out what we expect the structure of the solver to look like, and we've already gotten that merged into the source tree.

Finally, Chalk is no longer going to be a focus of the team. In the short term, it still may remain a useful tool for experimentation. As said before, rust-analyzer uses Chalk as its trait solver. It's also able to be used in rustc under an unstable feature flag. Thus, new ideas currently could be implemented in Chalk and battle-tested in practice. However, this benefit will likely not last long as a-mir-formality and the new in-tree trait solver get more usable and their interfaces become more accessible. All this is not to say that Chalk has been a failure. In fact, Chalk has taught us a lot about how to think about the Rust trait solver in a logical way and the current Rust trait solver has evolved over time to more closely model Chalk, even if incompletely. We expect to still support Chalk in some capacity for the time being, for rust-analyzer and potentially for those interested in experimenting with it.

Closing soundness holes

As brought up previously, a big benefit of creating a new types team with delegated authority from both the lang and compiler teams is the authority to assess and fix unsoundness issues mostly independently. However, a secondary benefit has actually just been better procedures and knowledge-sharing that allows the members of the team to get on the same page for what soundness issues there are, why they exist, and what it takes to fix them. For example, during our meetup earlier this month, we were able to go through the full list of soundness issues (focusing on those relevant to the type system), identify their causes, and discuss expected fixes (though most require prerequisite work discussed in the previous section).

Additionally, the team has already made a number of soundness fixes and has a few more in-progress. I won't go into details, but instead am just opting to putting them in list form:

Consider unnormalized types for implied bounds: landed in 1.65, no regressions found
Neither require nor imply lifetime bounds on opaque type for well formedness: landed in 1.66, no regressions found
Add IMPLIED_BOUNDS_ENTAILMENT lint: landing in 1.68, future-compat lint because many regressions found (of unsoundness)
Check ADT fields for copy implementations considering regions: currently open, ready to land
Register wf obligation before normalizing in wfcheck: currently open, regressions found, needs additional work
Handle projections as uncovered types during coherence check: currently open, some regressions found, future-compat lint suggested
Don't normalize in AstConv: landing in 1.68, 1 small regression found

As you can see, we're making progress on closing soundness holes. These sometimes break code, as assessed by crater. However, we do what we can to mitigate this, even when the code being broken is technically unsound.

New features

While it's not technically under the types team purview to propose and design new features (these fall more under lang team proper), there are a few instances where the team is heavily involved (if not driving) feature design.

These can be small additions, which are close to bug fixes. For example, this PR allows more permutations of lifetime outlives bounds than what compiled previously. Or, these PRs can be larger, more impactful changes, that don't fit under a "feature", but instead are tied heavily to the type system. For example, this PR makes the Sized trait coinductive, which effectively makes more cyclic bounds compile (see this test for an example).

There are also a few larger features and feature sets that have been driven by the types team, largely due to the heavy intersection with the type system. Here are a few examples:

Generic associated types (GATs) - The feature long predates the types team and is the only one in this list that has actually been stabilized so far. But due to heavy type system interaction, the team was able to navigate the issues that came on its final path to stabilization. See this blog post for much more details.
Type alias impl trait (TAITs) - Implementing this feature properly requires a thorough understanding of the type checker. This is close to stabilization. For more information, see the tracking issue.
Trait upcasting - This one is relatively small, but has some type system interaction. Again, see the tracking issue for an explanation of the feature.
Negative impls - This too predates the types team, but has recently been worked on by the team. There are still open bugs and soundness issues, so this is a bit away from stabilization, but you can follow here.
Return position impl traits in traits (RPITITs) and async functions in traits (AFITs) - These have only recently been possible with advances made with GATs and TAITs. They are currently tracked under a single tracking issue.

Roadmap

To conclude, let's put all of this onto a roadmap. As always, goals are best when they are specific, measurable, and time-bound. For this, we've decided to split our goals into roughly 4 stages: summer of 2023, end-of-year 2023, end-of-year 2024, and end-of-year 2027 (6 months, 1 year, 2 years, and 5 years). Overall, our goals are to build a platform to maintain a sound, testable, and documented type system that can scale to new features need by the Rust language. Furthermore, we want to cultivate a sustainable and open-source team (the types team) to maintain that platform and type system.

A quick note: some of the things here have not quite been explained in this post, but they've been included in the spirit of completeness. So, without further ado:

6 months

The work-in-progress new trait solver should be testable
a-mir-formality should be testable against the Rust test suite
Both TAITs and RPITITs/AFITs should be stabilized or on the path to stabilization.

EOY 2023

New trait solver replaces part of existing trait solver, but not used everywhere
We have an onboarding plan (for the team) and documentation for the new trait solver
a-mir-formality is integrated into the language design process

EOY 2024

New trait solver shared by rustc and rust-analyzer
- Milestone: Type IR shared
We have a clean API for extensible trait errors that is available at least internally
"Shiny features"
- Polonius in a usable state
- Implied bounds in higher-ranked trait bounds (see this issue for an example of an issue this would fix)
- Being able to use impl Trait basically anywhere
Potential edition boundary changes

EOY 2027

(Types) unsound issues resolved
Most language extensions are easy to do; large extensions are feasible
a-mir-formality passes 99.9% of the Rust test suite

Conclusion

It's an exciting time for Rust. As its userbase and popularity grows, the language does as well. And as the language grows, the need for a sustainable type system to support the language becomes ever more apparent. The project has formed this new types team to address this need and hopefully, in this post, you can see that the team has so far accomplished a lot. And we expect that trend to only continue over the next many years.

As always, if you'd like to get involved or have questions, please drop by the Rust zulip.

Security advisory for Cargo (CVE-2022-46176)

2023-01-10

This is a cross-post of the official security advisory. The official advisory contains a signed version with our PGP key, as well.

The Rust Security Response WG was notified that Cargo did not perform SSH host key verification when cloning indexes and dependencies via SSH. An attacker could exploit this to perform man-in-the-middle (MITM) attacks.

This vulnerability has been assigned CVE-2022-46176.

Overview

When an SSH client establishes communication with a server, to prevent MITM attacks the client should check whether it already communicated with that server in the past and what the server's public key was back then. If the key changed since the last connection, the connection must be aborted as a MITM attack is likely taking place.

It was discovered that Cargo never implemented such checks, and performed no validation on the server's public key, leaving Cargo users vulnerable to MITM attacks.

Affected Versions

All Rust versions containing Cargo before 1.66.1 are vulnerable.

Note that even if you don't explicitly use SSH for alternate registry indexes or crate dependencies, you might be affected by this vulnerability if you have configured git to replace HTTPS connections to GitHub with SSH (through git's url.<base>.insteadOf setting), as that'd cause you to clone the crates.io index through SSH.

Mitigations

We will be releasing Rust 1.66.1 today, 2023-01-10, changing Cargo to check the SSH host key and abort the connection if the server's public key is not already trusted. We recommend everyone to upgrade as soon as possible.

Patch files for Rust 1.66.0 are also available here for custom-built toolchains.

For the time being Cargo will not ask the user whether to trust a server's public key during the first connection. Instead, Cargo will show an error message detailing how to add that public key to the list of trusted keys. Note that this might break your automated builds if the hosts you clone dependencies or indexes from are not already trusted.

If you can't upgrade to Rust 1.66.1 yet, we recommend configuring Cargo to use the git CLI instead of its built-in git support. That way, all git network operations will be performed by the git CLI, which is not affected by this vulnerability. You can do so by adding this snippet to your Cargo configuration file:

[net]
git-fetch-with-cli = true

Acknowledgments

Thanks to the Julia Security Team for disclosing this to us according to our security policy!

We also want to thank the members of the Rust project who contributed to fixing this issue. Thanks to Eric Huss and Weihang Lo for writing and reviewing the patch, Pietro Albini for coordinating the disclosure and writing this advisory, and Josh Stone, Josh Triplett and Jacob Finkelman for advising during the disclosure.

Updated on 2023-01-10 at 21:30 UTC to include additional mitigations.

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