Unstable code formatting involving some macros (every rustfmt run indents some lines further)

[chris-morgan]

Sample code, minimised as far as I was able:

macro_rules! alpha {
    () => {
        macro_rules! beta {
            () => {
                gamma!(
                    *
                )
            };
        }
    };
}

Every time you run rustfmt over it, it indents lines 4–9 by another two levels.

Closely related, if you remove the first and last two lines (the outer macro_rules layer), formatting leaves lines 4–9 at whatever level it finds them rather than correcting their indentation. (But this is probably better than indenting them by two levels.)

Reproduced on rustc 1.57.0-nightly (c3c0f80 2021-09-14).

[chris-morgan]

Oops, saw A-rustfmt and figured bugs were going here, but after posting I thought to look further and found the rustfmt repository where has a couple of reports of this exact issue, e.g. rust-lang/rustfmt#4609. What’s the deal with A-rustfmt versus the rustfmt repository? Anyway, closing in favour of that issue.