paper-wars regression

[compiler-errors]

It's related to the fact that the Iterator is higher-ranked.

https://crater-reports.s3.amazonaws.com/pr-133502-13/try%233cddd79d4be3c8f1e937d09ca618d192abc69373/gh/foxfriends.paper-wars/log.txt

struct Module;
fn modules() -> Vec<Module> {
    todo!()
}

fn locate_tests<'a>(module: &'a Module) -> impl Iterator<Item = Vec<&'a ()>> {
    modules()
        .iter()
        .flat_map(locate_tests)
        .for_each(|mut x| {
            x.push(&());
        });
    [].into_iter()
}