Code shared from the Rust Playground

playground.rs

fn iterate_with_iterator<T: std::fmt::Display, I: Iterator<Item = T>>(iter: I) {
    for x in iter {
         println!("{}", x);
    }
}

fn iterate_with_boxed_iterator<'a, T: std::fmt::Display>(iter: Box<dyn Iterator<Item = T> + 'a>) {
    for x in iter {
         println!("{}", x);
    }
}

fn iterate_with_deref_boxed_iterator<'a, T: std::fmt::Display>(iter: Box<dyn Iterator<Item = T> + 'a>) {
    let diter = *iter;
    for x in diter {
         println!("{}", x);
    }
}

fn main() {
    let test = String::from("test");
    iterate_with_iterator(test.chars());
    iterate_with_boxed_iterator(Box::new(test.chars()));
}