for (key, value) in array![0, 1, 2].into_iter().enumerate() {
    assert_eq!(key, value);
}

// Or:
let mut iter = array![0, 1, 2].into_iter().enumerate();
while let Option::Some((k, v)) = iter.next() {
    assert_eq!(k, v);
}

error: Unexpected type for tuple pattern. "?125" is not a tuple.
    for (key, value) in array![0, 1, 2].into_iter().enumerate() {
        ^^^^^^^^^^^^

for (key, value) in array![(0, 0), (1, 1), (2, 2)].into_iter() {
    assert_eq!(key, value);
}