[Tracking] `rust-lang/rustfmt` fixes not yet synced to `rust-lang/rust`

[shulaoda]

Summary

This issue tracks reports that may already be fixed upstream in rust-lang/rustfmt, but are still reproducible in the version of rustfmt shipped with rust-lang/rust. Some of these issues may also be regressions introduced by recent changes in rustc, which can‘t be directly verified in the upstream repository.

Background

I’ve been trying to contribute fixes for some issues and noticed that they work correctly when testing against the upstream rust-lang/rustfmt repository, but not in the latest released nightly toolchain.

This happens because the copy of rustfmt included in rust-lang/rust (under src/tools/rustfmt) has not been synchronized with upstream for quite some time. The team is aware of this and is actively working to improve the situation. A new synchronization plan is in progress at rust-lang/rustfmt#6681.

Related Issues

• error[internal]: left behind trailing whitespace #6676
• format comments bug: comment merges with the next line even if it's a code block opener #6675
• rustfmt failed with use underscore prefixed name #6668

Note: The current conclusions are based on the state before the sync. They should be revalidated after rust-lang/rustfmt#6681 is merged and the next nightly includes the updated rustfmt.

[shulaoda]

This is just my personal conclusion after trying to investigate and fix the issue. Please feel free to correct me or close this if it doesn’t make sense. I’ll keep this updated as I continue working on potential fixes.

[calebcartwright]

Thank you! This is actually helpful because we're unfortunately not tied into the project's main release notes system and have to try to build these out ourselves every time we do a subtree sync

[calebcartwright]

Another indicator to look for to identify potential items would be issues or PRs with the release-notes label https://github.com/rust-lang/rustfmt/issues?q=state%3Aopen%20label%3Arelease-notes

[Manishearth]

According to @ytmimi the two issues that need to be merged on the rustfmt side to unblock syncing back into rustc are:

• Revert "defer changes for zero argument functions until style_edition=2027" #6595
• defer version sorted modules until style-edition 2027 #6594