unchecked-suppress.scala:4: warning: non-variable type argument Int in type pattern scala.collection.immutable.Set[Int] (the underlying of Set[Int]) is unchecked since it is eliminated by erasure
    case xs: Set[Int]                              => xs.head   // unchecked
             ^
unchecked-suppress.scala:5: warning: non-variable type argument String in type pattern scala.collection.immutable.Map[String @unchecked,String] (the underlying of Map[String @unchecked,String]) is unchecked since it is eliminated by erasure
    case xs: Map[String @unchecked, String]        => xs.head   // one unchecked, one okay
             ^
unchecked-suppress.scala:7: warning: non-variable type argument Int in type pattern (Int, Int) => Int is unchecked since it is eliminated by erasure
    case f: ((Int, Int) => Int)                    =>           // unchecked
                        ^
error: No warnings can be incurred under -Xfatal-warnings.
three warnings found
one error found