Emulate C's (polymorphic) NULL type

[Anonymouse via Digitalmars-d-learn]

On Monday, 6 June 2016 at 09:43:23 UTC, ParticlePeter wrote:
> 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?

If you want it for use in logical expressions then implicit 
boolean conversion will treat them as the same.

https://dpaste.dzfl.pl/d82f60657c37