ICE in rollup

[Dylan-DPC]

ICE encountered in a rollup, will post more details when i trace it further:

[Urgau]

I am able to reproduce the issue with this code and rustc -Z unstable-options --check-cfg=names():

macro_rules! aa {
    () => {
        fn gg() {
            #[cfg(crossbeam_loom)]
            {
                let _ = val;
                unimplemented!("loom does not support non-atomic atomic ops");
            }
        }
    };
}

fn main() {
    aa!();
}

And it's combination of #94433 ("introduce" the ICE, preexisting issue) and #94298 (trigger the lint which trigger the ICE).

[Urgau]

Further reduced to:

fn main() {
    #[cfg(crossbeam_loom)]
    {}
}