Pattern matching: both Some(..) and Some(_) work?

[scribu]

In The Rust Guide, in the Patterns section, it says:

If you're matching on an enum which has variants, you can use .. to ignore the value in the variant:

match x {
    Value(..) => println!("Got an int!"),
    Missing   => println!("No such luck."),
}

but then in the Consumers section, Some(_) is used:

match greater_than_forty_two {
    Some(_) => println!("We got some numbers!"),
    None    => println!("No numbers found :("),
}

Why are both wildcard variants — .. and _ — allowed? Some(_) seems less surprising to me.

[Gankra]

This is just an odd intersection of two features. .. omits arbitrarily many arguments, but _ omits only one. Thus, if there is exactly one argument, then both are valid constructions. A possible "solution" could be making .. inadmissible for single-value enums.

enum Foo {
    A(uint, uint), B(uint),
}

fn main() {
    match B(0) {
        A(_) => println!("A!"),
        B(_) => println!("B!"),
    }
}

Gives

<anon>:7:9: 7:13 error: this pattern has 1 field, but the corresponding variant has 2 fields [E0023]
<anon>:7         A(_) => println!("A!"),
                 ^~~~

enum Foo {
    A(uint, uint), B(uint),
}

fn main() {
    match B(0) {
        A(..) => println!("A!"),
        B(..) => println!("B!"),
    }
}

Compiles fine

[scribu]

Ah, I see. Thanks!

Don't know how it could be fixed or even if it's actually a problem. Closing.