- The options `infodir`, `localstatedir`, and `gpg-password-file` are no longer allowed in config.toml. Previously, they were ignored without warning. Note that `infodir` and `localstatedir` are still accepted by `./configure`, with a warning. [#82451](https://github.com/rust-lang/rust/pull/82451)
- Add options for enabling overflow checks, one for std (`overflow-checks-std`) and one for everything else (`overflow-checks`). Both default to false.
- Change the names for `dist` commands to match the component they generate. [#90684](https://github.com/rust-lang/rust/pull/90684)
+- The `build.fast-submodules` option has been removed. Fast submodule checkouts are enabled unconditionally. Automatic submodule handling can still be disabled with `build.submodules = false`.
### Non-breaking changes