The most short and elegant example I could come up with that actually worked (since the example above really shouldn't work in Rust in the first place):

    fn main() {
        let mut v = vec![1, 2, 3, 4, 5];
        let new_size = v.len()*2;
        v = v.into_iter().cycle().take(new_size).collect();
    
        println!("{:?}", v);
    }

https://play.rust-lang.org/?version=stable&mode=debug&editio...