immutable postblit unusable?

[Steven Schveighoffer]

On 2/11/18 3:25 AM, Jonathan M Davis wrote:
> In the case of immutable, the postblit is actually completely unnecessary,
> because there's no need to do a deep copy of an immutable object, since it's
> guaranteed to never change its value (whereas with const, a deep copy can
> still be necessary, since other references to that data may be mutable and
> could thus change the data).

What about reference counting? Essentially, you could be changing values 
external to the type itself.

I don't think postblit should be illegal on immutable types.

-Steve