upgrade-rust.md

Upgrading Rust

Materialize builds with the stable release of Rust, which gets updated every 6 weeks. We try to pretty aggressively track the latest version to get the newest features and make upgrades as easy as possible.

Anyone is welcome to upgrade the version of Rust! Below is the list of things you need to do:

1. Bump the rust-version field in our Workspace Cargo.toml and in the Bazel WORKSPACE.
2. Bump the NIGHTLY_RUST_DATE value in the ci-builder script.
   • Note: CI has a nightly version of Rust so we can run Miri.
3. Locally run rustup upgrade stable to pull the latest version of the Rust toolchain, or whatever version you're upgrading to.
4. From the root of the repository run cargo clippy --workspace --tests, fix any new clippy lints that were introduced.
5. Check if Rust's unicode version has changed. If it has make sure to include in the release notes what version it previously was, and what version it got bumped to.
   • The Releases page for the Rust repository should mention if it's been changed. But the only way to know for sure it to git blame the UNICODE_VERSION const.
6. When the upgrade PR finally merges, post in #eng-general to give everyone a heads up and let them know they can upgrade by running rustup upgrade stable.