rustfmt deletes comment after arrow in Fn type

[findepi]

Input:

fn foo(f: &dyn Fn(i32) -> /*result*/ i32)  {
}

after rustfmt becomes

fn foo(f: &dyn Fn(i32) -> i32) {}

Expected

Preserve /*result*/ comment

Observed

Comment deleted.

[ytmimi]

Thanks for the report. This feels related to https://github.com/rust-lang/rustfmt/issues/5874

[findepi]

Thanks for the link! I didn't find that issue because I was searching with Fn. Feel free to close as duplicate.

[jieyouxu]

Triage: it does feel related to #5874, though worth keeping separate since this is removing a comment in a param type decl position.