Do not yeet unsafe<> from type when formatting unsafe binder

[compiler-errors]

Unsafe binders are types like unsafe<'a, 'b> Ty<'a, 'b>. However, users can also specify unsafe binder types with no bound vars, like unsafe<> Ty.

When I added nightly formatting for unsafe binders, I didn't consider this, so on nightly we are stripping the unsafe<> part, which gives us back Ty which is a different type!

This PR fixes that.

r? @ytmimi

[rustbot]

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

[compiler-errors]

Cannot remember if you have r+, so

@bors delegate=ymtimi

[bors]

✌️ @ymtimi, you can now approve this pull request!

If @compiler-errors told you to "r=me" after making some further change, please make that change, then do @bors r=@compiler-errors

[ytmimi]

@bors r+

[bors]

@ytmimi: 🔑 Insufficient privileges: Not in reviewers

[compiler-errors]

:/// I typoed your name in the delegate. sorry!

@bors r=ytmimi

[bors]

📌 Commit 5bf2237 has been approved by ytmimi

It is now in the queue for this repository.

[ytmimi]

All good. This was a nice and simple PR!

[ytmimi]

Do you know who I need to reach out to in order to get the right privileges to approve PRs?

[compiler-errors]

cc @calebcartwright

T-rustfmt should definitely have bors permissions in this repo, at least with the understanding that the permissions will only be used for rustfmt subtree syncs and the occasional in-tree rustfmt PR.

You should open a teams PR that adds these lines to rustfmt.toml:

[permissions]
bors.rust.review = true