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(&());
        });
    std::iter::empty()
}

[lcnr]

probably a generalization/hr closure signature inference issue 🤔

[lcnr]

fn rarw<'a>(_: &'a ()) -> impl Iterator<Item = Vec<&'a ()>> {
    std::iter::once(&()).flat_map(rarw).for_each(|mut x| {
        x.push(&());
    });
    std::iter::empty()
}

[lcnr]

#[allow(unused)]
fn flat_map<T, F, I, G>(_: F, _: G)
where
    F: FnOnce(T) -> I,
    I: Iterator,
    G: Fn(<I as Iterator>::Item) -> usize,
{
}

fn rarw<'a>(_: &'a ()) -> impl Iterator<Item = &'a str> {
    flat_map(rarw, |x| x.len());
    std::iter::empty()
}