rustfmt no longer builds after rust-lang/rust#83454

[rust-highfive]

Hello, this is your friendly neighborhood mergebot.
After merging PR #83454, I observed that the tool rustfmt no longer builds.
A follow-up PR to the repository https://github.com/rust-lang/rustfmt is needed to fix the fallout.

cc @JohnTitor, do you think you would have time to do the follow-up work?
If so, that would be great!

[klensy]

Almost 2 weeks no rustfmt, that prevents default nightly update process via rustup update (without manually selecting components) and generates some number of duplicated issues, as some reporters use default nighly-2021-03-24.

[Berrysoft]

Seems that rustfmt has fixed that. Any progress?

[calebcartwright]

Folks as always there's a sequence of PRs that have to be made across various repos before the submods can be updated with the fix here. Those PRs have been linked and can be seen above, but will explicitly enumerate them in a comment for reference

At a minimum the steps will include:

• (1) bump rustc-ap* in racer and publish new version on crates.io (bump rustc-ap crates to v712 racer-rust/racer#1163)
• (1) bump rustc-ap* on rustfmt ([1.x] bump rustc-ap crates to v712 rustfmt#4775)
• (2) update racer and rustfmt references in rls (bump racer and rustfmt rls#1726)
• (3) update rustfmt and rls submods in rust-lang/rust repo (update RLS and rustfmt #84103)

Note that the rustc-ap bumps in racer and rustfmt can be done in parallel (step 1's), the other tasks all have to be sequenced

[calebcartwright]

Seems that rustfmt has fixed that. Any progress?

Want to note that the PR linked to there is not related to the broken toolstate/resolving this issue