Make array patterns match on [T, ..n] and [T] only

[ftxqxd]

Array patterns currently match on either &[T] or [T, ..n]:

let x: &[int] = &[1, 2, 3];
let y: Box<[int]> = box [1, 2, 3];
let z: [int, ..3] = [1, 2, 3];

// Does not work
match x {
    &[1, 2, 3] => {},
    _ => {},
}

// Does not work
match y {
    box [1, 2, 3] => {},
    _ => {},
}

// Does work
match z {
    [1, 2, 3] => {},
    _ => {},
}

// Does work
match x {
    [1, 2, 3] => {},
    _ => {},
}

Logically, array patterns should only work on the bare array types, [T, ..n] and [T]. That would mean that all array patterns that match on &[T] would have to be prefixed by &, but it would also allow matching on Box<[T]> (and hypothetically, Rc<[T]>, Arc<[T]> etc. eventually). Has this already been considered (perhaps as part of DST)?

[brendanzab]

+1. This is definitely confusing for some folks.

[Stebalien]

Triage: Closed by #495?

[Centril]

Yes, I think so - closing.