Nothing is not nullable

Author: odersky

src/dotty/tools/dotc/core/SymDenotations.scala

@@ -616,7 +616,7 @@ object SymDenotations {
 
     /** Is this symbol a class references to which that are supertypes of null? */
     final def isNullableClass(implicit ctx: Context): Boolean =
-      isClass && !isValueClass && !(this is ModuleClass)
+      isClass && !isValueClass && !(this is ModuleClass) && symbol != defn.NothingClass
 
     /** Is this definition accessible as a member of tree with type `pre`?
      *  @param pre          The type of the tree from which the selection is made