`interactive-form` symbol property (was: [Emacs-diffs] emacs-26 9a53b6d: Say how to override a primitive interactive spec)

[Stefan Monnier]

>> +If you wish to override a primitive interactive specification, just
>> +set the @code{interactive-form} property of the primitive function's
>> +symbol (@pxref{Using Interactive}).  There is no need to edit C code
>> +and recompile Emacs.
> You can also use advice-add for the same purpose (it's more
> complicated, but it's arguably better behaved).

And a quick search seems to indicate that this `interactive-form`
property is not used anywhere (not within Emacs, not within GNU ELPA,
and not within the few other Elisp packages I had lying around for
a quick search).

Maybe, rather than document it, we should obsolete it?


        Stefan