Re: Not protecting Lisp objects from GC

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

> If someone suggests a simpler, cleaner change, I might reconsider.

We are now in a situation where the feature/igc developers are
protesting vehemently against this, to the extent that there is even
talk of not merging feature/igc at all.  This is not a good outcome.

One side in this discussion argue that removing DEFVAR_LISP_NOPRO is
risk-free, or something close to it, and decreases the risk for GC bugs.

The other side argues that any change comes with inherent risk,
especially in a currently poorly understood area like font.c, and that
keeping what we have is low risk.

Since this discussion seems to revolve around managing risk in different
ways, I would suggest the following compromise:

1. We install the attached patch on master _as an experiment_, which
   means that we install it with the understanding that we are keeping
   the option open to revert it later.  We have used this method in the
   past to good effect.

2. We agree to re-evaluate the patch before the fist pretest for Emacs
   31.1, or even sooner, keeping the option open to revert it if needed.

3. If there is no trouble with the patch, we leave it as is.  The
   pretest will give us more opportunities to get this change tested in
   various configurations.

4. We keep the option open to revert it at any point during the pretest
   also, if it turns out to be causing issues.

I hope that this could make everyone happy, and let us get back to our
regularly scheduled hacking.

Can everyone please let me know what they think?

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