Lubos Pintes:
> I see no "void" there, except that foo has a return type of 
> void.
Minimized:
enum Foo : void* {
     a = null
}
void main() {
     auto f = Foo.a;
}
enums are good for ints, ubytes, longs, chars, etc. The more 
types you try to put in them, the more compiler holes you will 
find.
Bye,
bearophile