duplicates:

• SR-483 Exhaustivity checking for switch statement with wildcards doesn't work properly

Issue Description:

This code, which ought to be legal, produces an error:

func f(x: Int?, y: Int?) {
    switch (x, y) {
    case (let x?, _):
        _ = x
        break
    case (_, let y?):
        _ = y
        break
    case (nil, nil):
        break
    }
// switch must be exhaustive, consider adding a default clause
}

I believe the switch is actually exhaustive (the first two cases cover all possibilities where x or y have any non-nil value, and the last case covers the final nil, nil possibility) but the compiler isn't able to detect that.