#![allow(unused_variables)]
fn main() {
    use std::collections::VecDeque;
    let mut buf = VecDeque::new();
    buf.push_back(5);
    buf.push_back(10);
    buf.push_back(15);
    assert_eq!(buf, [5, 10, 15]);
    buf.resize_with(5, Default::default);
    assert_eq!(buf, [5, 10, 15, 0, 0]);
    buf.resize_with(2, || unreachable!());
    assert_eq!(buf, [5, 10]);
    let mut state = 100;
    buf.resize_with(
        5,
        || {
            state += 1;
            state
        },
    );
    assert_eq!(buf, [5, 10, 101, 102, 103]);
}