// Doesn't work
struct X {
    let z: String? = "xyz"
    let omega: [String]? = [ "abc", "xyz" ]
}

extension X: Equatable {
    public static func ==(x: X, y: X) -> Bool {
        return x.z == y.z && // value of optional type 'String?' not unwrapped; did you mean to use '!' or '?'?
            x.omega == y.omega // value of optional type '[String]?' not unwrapped; did you mean to use '!' or '?'?
    }
}