Re: Not protecting Lisp objects from GC

[Gerd Möllmann]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Cc: emacs-devel@gnu.org
>> Date: Mon, 27 Jan 2025 14:26:42 +0100
>> 
>> The comment you added mentions a case where DEFVAR_LISP_NOPRO is used in
>> exactly the way I described. That needs to be fixed!
>
> AFAIU, we've fixed that already on the igc branch, in the MPS build,

These things obviously need to be fixed on master when they are found.
It has nothing to do with igc.

> in the sense that this macro was effectively removed in favor of
> DEFVAR_LISP.  So when the igc branch lands, we will have that solved
> on master, when building with MPS (which I hope will be what most of
> the supported platforms will use).
>
> In the non-MPS build, the changes which were proposed to remove its
> use messed with special-purpose code in a way that I felt uneasy with,
> so I preferred to leave the existing code alone.  I have my share of
> gray hair from making changes in font.c and fontset.c.  If someone
> suggests a simpler, cleaner change, I might reconsider.
>
>> Just adding a comment is accepting it, and is worse than as writing
>> such code in the first place.
>
> Sorry, I fail to understand how describing some existing code could be
> bad.  "Security by obscurity" doesn't really work, as we all know, and
> maintainers have to deal with code that they don't like every day, so
> helping them understand tricky corners cannot be bad, IMO.
>
>> The old GC won't go away for many years.
>
> Maybe not, but then the code in question worked for us for decades, so
> a probability of a serious error there is quite low, to say the least.

What you are doing is not fixing obvious maintainability bugs which
might also show up as real bugs in production. You are writing comments
instead. In another branch. And from what I read so far, I get the
impression that you are objecting to others making the fixes, in that
branch.

Not sure what I should think about this.