Slice/Array patterns are not correctly move checked

[matthewjasper]

The following should error, but doesn't

#![feature(slice_patterns)]

fn main() {
    let a = [String::from("HELLO"), String::from("WORLD")];
    let [_, mut x] = a;
    x = String::from("RUST");
    let [ref y @ ..] = a;
    println!("{:?}", y); 
}

[jonas-schievink]

cc #62254

[matthewjasper]

This doesn't require nightly:

#![allow(unused)]

fn main() {
    let a = [(String::from("HELLO"), String::from("WORLD"))];
    let [mut x] = a;
    x = (String::from("GOODBYE"), String::from("RUST"));
    let [(ref y, ref z)] = a;
    println!("{:?}", (y, z));
}

playground