Open Radar

 
This Swift code makes the compiler reproducibly crash on my machine. Works in a playground or a regular source file.

extension SequenceType {
    func invert<Key, Value: Hashable where Generator.Element == (Key, Value)>() -> [Value: Key] {
        var inverted = [Value: Key]()
        for item in self {
            let (key, value) = item as! (Key, Value)
            inverted[value] = key
        }
        return inverted
    }
}