I wrote:
> Although I've left the patch throwing an error (with new wording)
> for now, I wonder if it'd be better to reduce the error to a NOTICE,
> perhaps worded like "function f will be effectively temporary due to
> its dependence on <object>".
This is, of course, pretty much what you suggested originally.
So I apologize for leading you down the garden path of
it-should-be-an-error. I'd still argue for raising an error
if we were working in a green field, but we're not.
regards, tom lane