Announcing Rust 1.45.1

July 30, 2020 · The Rust Release Team

The Rust team is happy to announce a new version of Rust, 1.45.1. 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 1.45.1 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, and check out the detailed release notes for 1.45.1 on GitHub.

What's in 1.45.1 stable

1.45.1 contains a collection of fixes, including one soundness fix. All patches in 1.45.1 address bugs that affect only the 1.45.0 release; prior releases are not affected by the bugs fixed in this release.

Fix const propagation with references

In Rust 1.45.0, rustc's const propagation pass did not properly handle encountering references when determining whether to propagate a given constant, which could lead to incorrect behavior. Our releases are run through crater, and we did not detect it, which helps us be fairly confident that this affects a very small set of code in the wild (if any).

The conditions necessary to cause this bug are highly unlikely to occur in practice: the code must have inputs consisting of entirely constant values and no control flow or function calls in between.

struct Foo {
    x: u32,

fn main() {
    let mut foo = Foo { x: 42 };
    let x = &mut foo.x;
    *x = 13;
    let y = foo;
    println!("{}", y.x); // -> 42; expected result: 13

Contributors to 1.45.1

Many people came together to create Rust 1.45.1. We couldn't have done it without all of you. Thanks!