bug#36403: 27.0.50; Trivial image.c bugs

[Lars Ingebrigtsen <larsi@gnus.org>]

Pip Cet <pipcet@gmail.com> writes:

> Paul's suggestion was to use equal () instead of !NILP (Fequal (...)).
> I'm against that, because the F in Fequal kind of hints at the
> difficulties of using equal, of which there are many: in the current
> implementation, it can signal, quit, be asymmetric (signalling for
> (equal a b) whereas (equal b a) works), and is susceptible to equality
> bombs that take forever to compare.

Yeah, your equal_lists is better in all ways, I think.  It should be
much faster, too -- Fequal on a list checks whether the string members
are equal, too, which is slow.  So I think this will speed things up if
you have a buffer that displays images where the data comes from a
string (which can be huge) instead of a file.

> Replacing !NILP is a better idea, but I'm struggling to come up with a
> good name for that. But even a bad name would be an improvement.

TRUEP is kinda obvious, isn't it?  Although I guess some people would
object on the grounds that only t is true, while all other non-nil
values are only trueish.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no