Re: Emacs 27.1 released

[Eli Zaretskii <eliz@gnu.org>]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Wed, 12 Aug 2020 21:07:05 +0200
> Cc: emacs-devel@gnu.org
> 
> > How easily would people bump into this in real-life use cases?  I
> > think the answer to that will tell how important is it to fix it in
> > Emacs 27.
> 
> We have no idea. Most bugs are never reported; people blame themselves and try a different approach, or just blame Emacs in general. That's why it's important to fix bugs we find even absent any concrete evidence that it has affected anyone else.

That kind of abstract arguments don't help.  So I'm left to my own
devices, and therefore please leave this change on master.

> >>> I'm uneasy with this, as it would indirectly affect many functions.
> >> 
> >> Which many functions did you have in mind?
> > 
> > Its callers inside Calc.  Suppose there's some subtle issue with the
> > change, or some unintended consequence.
> 
> Mind being more specific?

I just counted its callers, that's all.  A change in a function that
has many callers could have unintended consequences beyond the
function itself.

> >  OTOH, how probable is it to have a negative x here?
> 
> The post-hoc probability is 1 because a user was affected by and reported the bug, but that's not the point: the erroneous simplification GCD(x, 0) -> x leads to trouble later on, as the report shows.

I thought you were going to help me make a better decision, but I
guess I was too naïve.  Please leave this one on master as well.