use std::fmt::Display;

fn main() {
    let mut v = vec![1,2,3];
    do_bad_stuff(&mut v);
    print_elements(&v);
}

fn print_elements<T>(v: &[T])
    where T: Display
{
    for (i, element) in v.iter().enumerate() {
        println!("[{}] = {}", i, element);
    }
}

fn do_bad_stuff<T>(v: &mut[T]) {
    let v2 = &mut v[1..];
    v2.swap(0, 1);

    let v3 = &mut v[1..];
    v3.swap(0, 1);

    v.swap(0, 1);
}