Confusing unreachable pattern error

[pyfisch]

This simple code fails to compile because Other is not defined. But the error message is unreachable pattern [E0001] Bar => "bar". But Bar is not the cause it just happens to occur after Other.

enum Foobar {
    Foo,
    Bar,
}

fn main() {
    use Foobar::*;
    let x = Foo;
    println!("{}", match x {
        Foo => "foo",
        Other => "other",
        Bar => "bar",
    });
}

http://is.gd/zL6HGt

[apasel422]

I agree that this is confusing, though from the compiler's perspective, the error message makes sense. Since Other isn't a variant of Foobar, Other becomes the name of a binding that matches all possible values of x other than Foobar::Foo. (See https://doc.rust-lang.org/book/patterns.html.) Once that happens, the Bar case is indeed unreachable.

[apasel422]

Perhaps the error message could point to the match arm that the unreachable arm overlaps with.

[durka]

Also if you comment out the Bar arm, you get a snake-case warning on Other, but unfortunately the error happens first.

[pyfisch]

Thanks for your coments. Now at least I understand why the compiler printed this error message.

[nagisa]

Related: #5657