variance.scala

  import scala.reflect.runtime.universe.{TypeTag, typeOf}
  
  trait Foo[T]
  class Baz extends Foo[String]

  def foo[T <: String:TypeTag]: Class[_ <: Foo[T]] = typeOf[T] match {
    case t if t =:= typeOf[String] => classOf[Baz]
  }
  
// [error] ...: type mismatch;
// [error]  found   : Class[Baz](classOf[Baz])
// [error]  required: Class[? <: Foo[T]]
// [error] Note: Baz >: ? <: Foo[T], but Java-defined class Class is invariant in type T.
// [error] You may wish to investigate a wildcard type such as `_ >: ? <: Foo[T]`. (SLS 3.2.10)
// [error]     case t if t =:= typeOf[String] => classOf[Baz]
// [error]                                              ^