The Rust team has published a new point release of Rust, 1.91.1. 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, getting Rust 1.91.1 is as easy as:

rustup update stable

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

What's in 1.91.1

Rust 1.91.1 includes fixes for two regressions introduced in the 1.91.0 release.

Linker and runtime errors on Wasm

Most targets supported by Rust identify symbols by their name, but Wasm identifies them with a symbol name and a Wasm module name. The #[link(wasm_import_module)] attribute allows to customize the Wasm module name an extern block refers to:

#[link(wasm_import_module = "hello")]
extern "C" {
    pub fn world();
}

Rust 1.91.0 introduced a regression in the attribute, which could cause linker failures during compilation ("import module mismatch" errors) or the wrong function being used at runtime (leading to undefined behavior, including crashes and silent data corruption). This happened when the same symbol name was imported from two different Wasm modules across multiple Rust crates.

Rust 1.91.1 fixes the regression. More details are available in issue #148347.

Cargo target directory locking broken on illumos

Cargo relies on locking the target/ directory during a build to prevent concurrent invocations of Cargo from interfering with each other. Not all filesystems support locking (most notably some networked ones): if the OS returns the Unsupported error when attempting to lock, Cargo assumes locking is not supported and proceeds without it.

Cargo 1.91.0 switched from custom code interacting with the OS APIs to the File::lock standard library method (recently stabilized in Rust 1.89.0). Due to an oversight, that method always returned Unsupported on the illumos target, causing Cargo to never lock the build directory on illumos regardless of whether the filesystem supported it.

Rust 1.91.1 fixes the oversight in the standard library by enabling the File::lock family of functions on illumos, indirectly fixing the Cargo regression.

Contributors to 1.91.1

Many people came together to create Rust 1.91.1. We couldn't have done it without all of you. Thanks!