Emulate C's (polymorphic) NULL type

[ParticlePeter via Digitalmars-d-learn]

In C NULL can be used as integer as well as null pointer.
Is there a way to create such a type in D?

The type should have only one value which is obviously (0/null).
A extern( C ) function should be able to take it as either one.

Overloaded enum pops into my mind as example:
enum NULL = 0;
enum NULL = null;


Is this possible somehow?