Announcing Rust 1.52.1

Announcing Rust 1.52.1
Published At: 2021-05-10

The Rust team has prepared a new release, 1.52.1, working around a bug in incremental compilation which was made into a compiler error in 1.52.0. We recommend all Rust users, including those currently using stable versions prior to 1.52.0, upgrade to 1.52.1 or disable incremental compilation. Guidance on how to do so is available below.

This release works around broken builds on 1.52.0, which are caused by newly added verification. The bugs this verification detects are present in all Rust versions1, and can trigger miscompilations in incremental builds, so downgrading to a prior stable version is not a fix.

Users are encouraged to upgrade to 1.52.1 or disable incremental in their local environment if on a prior version: please see the what you should do section for details on how to do so.

Incremental compilation is off by default for release builds, so few production builds should be affected (only for users who have opted in).

Miscompilations that can arise from the bugs in incremental compilation generate incorrect code in final artifacts, essentially producing malformed binaries, which means that in theory any behavior is possible. In practice we are currently only aware of one particular known miscompilation, but bugs due to incremental are notoriously hard to track down: users frequently simply rebuild after some light editing if they see unexpected results from their binaries, and this often causes sufficient recompilation to fix the bug(s).