bug#21391: 24.5; `thing-at-point' should return a string

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> CC: Drew Adams <drew.adams@oracle.com>, Tino Calancha 
> <tino.calancha@gmail.com>,Eli Zaretskii <eliz@gnu.org>
> Date: Mon, 07 Nov 2016 12:17:17 +0900
> 
> Drew Adams <drew.adams@oracle.com> writes:
> 
> > A proper fix is to convert the result returned by
> > (funcall (get thing 'thing-at-point)) to a string.
> > For that, you can use (format "%s" thing).
> 
> It's natural if `thing-at-point' returns the thing as a string.
> When the user don't want a string then s?he can use the specific
> functions, like `number-at-point' or `list-at-point'.

Isn't that completely backward-incompatible?  If so, I don't think we
can do that.

I don't really see what is "improper" with the other suggestions to
fix this bug, which simply avoid signaling an error if the "thing at
point" happens to be something other than a string?