let-else binding in macro-rules makes unintended indent forever

[e0328eric]

For example, if one runs rustfmt on the following rust code

macro_rules! fmt_wrong {
    ($foo: ident := $bar: expr) => {
        let Some($foo) = $bar else {
            return; // This
        }; // This
    };
}

fn main() {
    println!("Hello, world!");
}

is formatted by indenting This parts. Each time one runs rustfmt, This parts are indented as much as we want.

[ytmimi]

Thanks for reaching out. This is a duplicate of #5213 and other related issues. This hopefully won't be an issue for much longer, and in the meantime you can follow #4914 to be informed when let-else support is available.

To prevent this issue for now your best option is to annotate your macro with the #[rustfmt::skip] attribute.

#[rustfmt::skip]
macro_rules! fmt_wrong {
    ($foo: ident := $bar: expr) => {
        let Some($foo) = $bar else {
            return; // This
        }; // This
    };
}