How scala generic constraints to nullable types work

Question

I\'ve tried two ways to constrain a generic type parameter to a nullable type, but both seem to have some unexpected problems.

First attempt (using T <: AnyRef):

Answer 1

def testAnyRefConstraint[T >: Null <: AnyRef](option:Option[T]):T = {
  option getOrElse null
}

I felt really stupid when I made this error the first time. Just because something extends AnyRef doesn't mean it must be nullable. For instance, Nothing is a subtype of AnyRef, and it is not nullable.

The other way around is similar, because Any is a supertype of Null, and any Int is also an Any.