thunderbird

The Rust team is happy to announce a new version of Rust, 1.96.0. 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 1.96.0 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 1.96.0.

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 1.96.0 stable

New `Range*` types

Many users expect Range and related core::ops types to be Copy, but this is not the case: they implement Iterator directly, and it is a footgun to implement both Iterator and Copy on the same type so this has been avoided. RFC3550 proposed a set of replacement range types that implement IntoIterator rather than Iterator, meaning they can also be Copy. The standard library portion of that RFC is now stable, introducing:

core::range::Range
core::range::RangeFrom
core::range::RangeInclusive
Associated iterators

A Rust version in the near future will also add core::range::RangeFull and core::range::RangeTo as re-exports from core::ops (these do not implement Iterator and already implement Copy), and core::range::legacy::* as the new home for the current ranges. Range syntax like 0..1 still produces the legacy types for now, but will be updated to core::range types in a future edition.

With these stabilizations, it is now possible to store slice accessors in Copy types without splitting start and end:

use core::range::Range;

#[derive(Clone, Copy)]
pub struct Span(Range<usize>);

impl Span {
    pub fn of(self, s: &str) -> &str {
        &s[self.0]
    }
}

The new RangeInclusive also makes its fields public, unlike the legacy version which avoided exposing the exhausted iterator state. This isn't a concern with the new type since it must be converted to begin iteration.

Library authors should consider making use of impl RangeBounds in public API, which accepts both legacy and new range types. If a concrete type is needed, prefer using new ranges as this will eventually become the default.

Assert matching patterns

The new macros assert_matches! and debug_assert_matches! check that a value matches a given pattern, panicking with a Debug representation of the value otherwise. These are essentially the same as assert!(matches!(..)) and debug_assert!(matches!(..)), but the printed value improves the possibility of diagnosing the failure.

These new macros have not been added to the standard prelude, because they would collide with popular third-party crates that provide macros with the same name. Instead, they should be manually imported from core or std before use.

use core::assert_matches;

/// [Random Number](https://xkcd.com/221/)
fn get_random_number() -> u32 {
    // chosen by a fair dice roll.
    // guaranteed to be random.
    4
}

fn main() {
    assert_matches!(get_random_number(), 1..=6);
}

Changes to WebAssembly targets

WebAssembly targets no longer pass --allow-undefined to the linker which means that undefined symbols when linking are now a linker error instead of being converted to WebAssembly imports from the "env" module. This change prevents modules from linking unless all linking-related symbols are defined to catch bugs earlier and prevent accidental issues with symbol naming or similar.

Undefined linking-related symbols are often indicative of build-time related bugs or misconfiguration. If, however, the old behavior is intended then it can be re-enabled with RUSTFLAGS=-Clink-arg=--allow-undefined or by editing the source code and using #[link(wasm_import_module = "env")] on the block defining the symbol.

This change was previously announced on this blog, and now takes effect in Rust 1.96.

Stabilized APIs

Two Cargo advisories

Rust 1.96 contains fixes for two vulnerabilities for users of third-party registries.

CVE-2026-5223 is a medium severity vulnerability regarding extraction of crate tarballs with symlinks.
CVE-2026-5222 is a low severity vulnerability regarding authentication with normalized URLs.

Users of crates.io are not affected by either vulnerability.

Other changes

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

Contributors to 1.96.0

Many people came together to create Rust 1.96.0. We couldn't have done it without all of you. Thanks!

28 May 2026 12:00am GMT

The latest version of PerfCompare is now live!

Check out the change-log below to see the updates:

[kala-moz]:

[padenot]: Use SJ bandwidth for top-level results, ISJ for subtests

[shtrom]: Bug 2014041: add support for landoInstance QueryString parameter (#1038 )

Thank you for the contributions!

Bugs or feature requests can be filed on Bugzilla. The team can also be found on the #perfcompare channel on Element. Come and chat!

1 post - 1 participant

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27 May 2026 9:29pm 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.

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Updates from Rust Community

Newsletters

Scientific Computing in Rust #18 (May 2026)

Project/Tooling Updates

Observations/Thoughts

Rust Walkthroughs

Miscellaneous

Content-addressed Rust builds (or, what kache actually caches)

Crate of the Week

This week's crate is inline_tweak, a crate to embed tweakable constants inside your Rust application without full recompilation.

Thanks to Kill The Mule for the suggestion!

Please submit your suggestions and votes for next week!

Calls for Testing

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

If you are a feature implementer and would like your RFC to appear in this list, add a call-for-testing label to your RFC along with a comment providing testing instructions and/or guidance on which aspect(s) of the feature need testing.

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

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

Call for Participation; projects and speakers

CFP - Projects

Always wanted to contribute to open-source projects but did not know where to start? Every week we highlight some tasks from the Rust community for you to pick and get started!

Some of these tasks may also have mentors available, visit the task page for more information.

rust cookbook - Expand Command Line section with clap derive, subcommands, and env vars

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

352 pull requests were merged in the last week

Compiler

Library

Cargo

Rustdoc

stabilize --remap-path-prefix in rustdoc

Clippy

Rust-Analyzer

Rust Compiler Performance Triage

This week was largely positive, with most of the improvements coming from algorithm change in visibility checking: #156228.

Triage done by @panstromek. Revision range: 281c97c3..783eb8c8

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.4%	[0.1%, 0.7%]	5
Regressions ❌ (secondary)	0.5%	[0.1%, 1.1%]	16
Improvements ✅ (primary)	-0.9%	[-6.6%, -0.1%]	164
Improvements ✅ (secondary)	-0.4%	[-1.3%, -0.1%]	51
All ❌✅ (primary)	-0.9%	[-6.6%, 0.7%]	169

2 Regressions, 2 Improvements, 5 Mixed; 2 of them in rollups 34 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:

Propose the concept of a crates.io username for identity

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

Compiler Team (MCPs only)

Rust

Rust RFCs

Avoid linting unreachable_code on todo!()

Unsafe Code Guidelines

What are the values of a union type? (in particular, what is the validity invariant of a union)

No Items entered Final Comment Period this week for Cargo, Language Team, Language Reference or Leadership Council. 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

No New or Updated RFCs were created this week.

Upcoming Events

Rusty Events between 2026-05-27 - 2026-06-24 🦀

South America

2026-06-18 | Florianópolis, BR | Rust SC
- Rust Floripa

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.