MBE doesn't bracket reference arguments

[lnicola]

CC #8961

struct Options {
    casei: Option<bool>,
}
const CASEI: Options = Options { casei: Some(true) };

macro_rules! toregex {
    ($name:ident, $options:expr) => {
        #[test]
        fn $name() {
            if let Some(casei) = $options.casei {
                foo(casei);
            }
        }
    };
}

toregex!(re_casei, &CASEI);

fn foo(_c: bool) {}

If you macro-expand toregex, it produces if let Some(casei) = &CASEI.casei, causing a compilation error and a and type mismatch. The correct expansion is if let Some(casei) = (&CASEI).casei.

[flodiebold]

Hmm isn't this supposed to work by introducing 'invisible' parens? But obviously something is going wrong there...

[lnicola]

I think so, and we had some changes related to token grouping, IIRC. We should still display the brackets for convenience, though.

[lnicola]

This was apparently fixed by #10044. For some reason, it doesn't reproduce without the #[test] attribute.