I wrote:
>I'm inclined to class this as "won't fix".  I have plans to implement
>a stricture pragma that would (within lexical scope) warn or die on
>compilation of any call to an undeclared sub.

I released that stricture pragma a couple of weeks after that, as
Sub::StrictDecl.  Since there's been no opposition to the view that I
expressed, this ticket should now be closed.

-zefram