Lifted generics to account for changes in rust-lang/rust#44766

[sunjay]

Following @alexcrichton's instructions here to fix the breakages caused by that PR.

A maintainer of rls/rustfmt (currently @nrc has done this but others can too!) will not merge the PR. The PR can't be merged because CI will be broken. Instead a new branch will be created, and the PR will be pushed to the branch (the PR is left open)

[sunjay]

If you expand the code above, you'll notice that generics is now being passed twice. Once as part of the ItemFn creation, and once as part of visit_fn. This redundancy is further reflected in visit_fn where the new generics argument is not actually used in the ItemFn variant of the match statement. (@nikomatsakis this is what I mentioned to you over chat)

[nrc]

Hey, sorry I haven't got to this for a while, I'm currently on parental leave. The PR looks fine and I can make a branch for this, however, I'm not sure about the parent - should this be rebased on top of current master? There are currently conflicts, which will make updating Rustfmt in the future difficult.

[sunjay]

@nrc Hi, no problem. I hope your parental leave is going well. :) We're currently working on getting this updated to the latest rustfmt master in the PR I linked to. No need to do anything with this until that's fixed. We're blocked on some stuff which is why this hasn't been updated, but that should all be resolved soon.

Thanks for taking the time even though you're on leave. :)

[sunjay]

@nrc This is ready for review now. It's now based on the latest master, so it can be merged with no conflicts. As mentioned when I first submitted this PR, please do not merge this yet. I don't think the CI will pass anyway, but I thought I'd mention it anyway. This PR is based on changes that haven't landed in rustc yet, so merging it would break a lot. The merge needs to be done in a certain sequence which @alexcrichton can advise about.

Please let me know if you'd like me to make any changes or if you have any questions about the changes I made already. Thanks! 😄

[nrc]

This is now the upstream branch lift-generics

[DSpeckhals]

This might still be causing test failures in rustc:

  --> src/tools/rustfmt/src/utils.rs:40:9
   |
40 |         Visibility::Crate(_) => Cow::from("pub(crate) "),
   |         ^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 1