In relation with enhancement JDK-7200915. In Type, it would be nice to get rid of the TypeTag tag field in every type, and use overload getTag in the various subtypes to return the correct value. But this is not as simple as it seems, since in various places direct instances of Type (not of any subtype) are created. This is because Type implements PrimitiveType. So, for another cleanup in this area, using a new subtype of Type for primitive types should be considered.