What is the output of this problem?

let x = 5, y = 10

switch (x, y) {
case (_, _):
    println("_, _")

case (5, _):
    println("5, _")

case (_, 10):
    println("_, 10")

case (5, 10):
    println("5, 10")
}

If you said, ", ", then great! If you're sad that case (5, 10): doesn't match… well, you're not alone.

Friendly reminder, always read your swift-statements like a chain of if-statements. With pattern matching in Swift, this could be the source of some inadvertent bugs, especially when adding new case clauses.

UPDATE: I filed rdar://21001503 about having a warning for case statements that can not be reached.