#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(iter_collect_into)]
fn main() {
    let a = [1, 2, 3];
    let mut vec: Vec<i32> = Vec::with_capacity(6);
    a.iter().map(|x| x * 2).collect_into(&mut vec);
    a.iter().map(|x| x * 10).collect_into(&mut vec);
    assert_eq!(6, vec.capacity());
    assert_eq!(vec, vec![2, 4, 6, 10, 20, 30]);
}