Could we reserve void[T] for builtin set of T ?

[Walter Bright via Digitalmars-d]

On 3/31/2016 12:44 PM, H. S. Teoh via Digitalmars-d wrote:
> Ah, makes sense.  But what would aa[x] return?

A bool indicating membership.

> And how would you add elements to it?

aa[x] = true;  // add member x
aa[x] = false; // remove member x
x in aa; // compile error