array indexing may not move

[lcnr]

fn fails_1(x: [String; 3], y: usize) {
    let q: String = x[y];
    //~^ ERROR cannot move out of type `[String; 3]`, a non-copy array
}

fn works_1(x: [String; 3], y: usize) {
    let _: String = x[y];
}

fn fails_2(x: [String; 3]) {
    let q: String = x[1];
    //~^ ERROR cannot move out of type `[String; 3]`, a non-copy array
}

fn works_2(x: [String; 3]) {
    let [_, q, _] = x;
    let [a, _, b] = x;
}

[lcnr]

however, we do consider there to be sub-places shared by all array elements, allowing the following to compile

fn main() {
    let mut x: [(u32, u32); 3] = Default::default();
    
    let y = &mut x[1].0;
    let z = &mut x[0].1;
    drop((y, z));
}

while this does not as all elements share a single place in borrowck

fn main() {
    let mut x: [(u32, u32); 3] = Default::default();
    
    let y = &mut x[1].0;
    let z = &mut x[0].0;
    drop((y, z));
}