bug#34114: 27.0.50: pdumper and themes with Emacs daemon

[Eli Zaretskii <eliz@gnu.org>]

> From: Karl Otness <karl@karlotness.com>
> Date: Fri, 18 Jan 2019 23:02:14 +0000
> Cc: Kaushal Modi <kaushal.modi@gmail.com>
> 
> I think I have found a change that fixes this issue. I haven't tested
> it too thoroughly, but it seems to work for me. The change is to call
> init_faces_initial from init_display_interactive even when Emacs is
> running as daemon.
> 
> In init_display_interactive in dispnew.c moving the lines:
> 
> > /* Set up faces of the initial terminal frame.  */
> > if (!noninteractive && NILP (Vinitial_window_system))
> >   init_faces_initial ();
> 
> from the end of the function so that they occur before the early
> return in the IS_DAEMON check (around line 6039) seems to fix the
> theme loading problem.

Thanks for identifying the code that's involved in this.

However, I'm not yet sure the solution you propose is the correct
one.  The way the code is written, it relies on the faces of the
initial frame to be initialized when Emacs is built, and then recorded
in the dumped Emacs.  With the pdumper approach, the record should be
in the emacs.pdmp file, and I'd expect it to be restored from there.

Why isn't this working?

If we want to repeat this initialization in the daemon when it starts
up, I'd like first to better understand the considerations for this
kind of situations: when we should fix such problems by recording and
restoring them to/from the dump file, and when we should run the
initialization code anew in the dumped Emacs.  The latter might mean
we cause more trouble elsewhere, because a lot of the code that runs
during startup expects stuff done in temacs to be available and ready
to use, not recomputed anew.

Daniel, can you comment on this aspect of the problem, including on
the more general issue?

In any case, if the proposed change is installed, it should not affect
the unexeced Emacs, so it IMO should be conditioned on
dumped_with_pdumper_p.  Unexeced Emacs should continue behaving as it
did before.

Thanks.