rustc/tests/run-make/sepcomp-separate/foo.rs

fn magic_fn() -> usize {
    1234
}

mod a {
    pub fn magic_fn() -> usize {
        2345
    }
}

mod b {
    pub fn magic_fn() -> usize {
        3456
    }
}

fn main() {
    magic_fn();
    a::magic_fn();
    b::magic_fn();
}