Pretty-printer inserts an extra newline before the first match arm if it has a comment

[petrochenkov]

Example:

fn main() {
    match 0u8 {
        // Comment
        0 => {}
        _ => {}
    }
}

=>

fn main() {
    match 0u8 {

        // Comment
        0 => {
        }
        _ => { }
    }
}

Affected tests:
[pretty] pretty\borrowck\borrowck-pat-enum.rs
[pretty] pretty\issue-11709.rs
[pretty] pretty\issue-28839.rs

[matklad]

[pretty] pretty/optional_comma_in_match_arm.rs

[wooster0]

I believe this can be closed.

fn main() {
    match 0u8 {
        // Comment
        0 => {}
        _ => {}
    }
}

This code stays just the way it is after I format.

[petrochenkov]

@r00ster91
This issue is about pretty-printing with AST pretty-printer in rustc, rather than about rustfmt.
It is available on https://play.rust-lang.org through "Tools > Expand macros", for example.
The issue still reproduces there.