two functions, two ways to write them

file.rs

fn name_to_path(name: &str) -> PathBuf {
    let mut iter = name.split("::");

    iter.next().unwrap(); // get rid of the initial name, since it's the crate name

    let mut path = PathBuf::new();

    iter.for_each(|component| {
        path.push(component);
    });

    path
}

fn name_to_path(name: &str) -> PathBuf {
    name.split("::").skip(1).fold(PathBuf::new(), |mut path, component| {
       path.push(component);
       path
    })
}

Obviously the 1nth. (You decide how the index works.)

Does this work ?

fn name_to_path(name: &str) -> PathBuf {
    name.split("::").skip(1).collect()
}

https://play.rust-lang.org/?gist=56a1b88765f90f210cb0ecd46abe8dba&version=stable