Enums with no values can be matched with (*)

[alexcrichton]

The following code compiles just fine, but I don't think that it should

enum A { B }

fn main() {
    match B {
        B(*) => {}
    }
}

Is that actually valid syntax? I would expect to get a compiler error that you can't ignore all fields when there are none to begin with.

[alexcrichton]

Nominating for the backwards-compatible milestone.

[catamorphism]

Is this a bug? "Ignore all fields" is trivially true when there are zero fields.

[thestinger]

I think this should be allowed, but see #5830 about the general inconsistency with these.

[alexcrichton]

I'm ok with that.