get address of object if opCast is overridden

[js.mdnq]

Let O be an object with opCast overridden, then


writeln(O); //prints string
writeln(cast(void *)O)) // error, works fine if I comment out the 
opCast override
writeln(&O) // address of pointer to O, not what I want.

I want to compare a few objects based on their location. (I know 
this is bad because of the GC, but I will probably pin them if I 
go this route)

It seems I have a difficult time getting the original behavior 
when something is syntactically overridden in D. I understand the 
point of cast(void *) not working when opCast is overridden but I 
then do not know how to still get the address.

Any Ideas?