Re: Shrinking the C core

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 9 Aug 2023 12:11:21 -0400
> From: "Eric S. Raymond" <esr@thyrsus.com>
> Cc: emacs-devel@gnu.org
> 
> Eli Zaretskii <eliz@gnu.org>:
> > For veteran and stable code such as this one, we should not rewrite
> > them in Lisp just because we can.  We should have much more serious
> > and good reasons for such changes.
> 
> Well, that's awkward.  I think I have a serious and good reason to
> shrink the core as much as possible, but it's one I'm not yet prepared
> to talk about because I don't want to over-promise.  I was hoping I
> could sneak up on it with a bunch of safe, small changes.

Sorry, no sneaking.  If you have some plan for serious changes, please
bring that up and let's talk about them.  It's quite possible that
what you have in mind would justify moving parts to Lisp.  But even
then, we should do that as little as possible, because our users don't
expect to get Emacs 30 that is significantly less stable than Emacs
29, and our bitter experience is that moving stuff to Lisp does just
that.

> >       Even the simple change you did a few days ago broke the build
> > on one system and raised a couple of issues some of which are not yet
> > resolved, and others we don't even have a good way of resolving except
> > by bracing for bug reports.
> 
> I want to understand the failure better, then, so I can avoid
> repeating it.  What build broke, and how?  What remaining issues are
> there?

I CC'ed you on the message which described that, see:

  https://lists.gnu.org/archive/html/emacs-devel/2023-08/msg00138.html

The build that broke was the MS-Windows build.  It broke because you
didn't replace Fdelete_file call in a function that is used only on
MS-Windows (that's the 3rd bullet in the list of issues I mention
there).

> (I did of course test te chane with a make bootstrap.)

Emacs has at least half a dozen different configurations and supported
platforms, and it's unreasonable to expect a bootstrap on one of them
to uncover all of the problems.  So I'm not surprised that you didn't
see the problems.  One more reason not to touch such code unless
really necessary.

Thanks.