Re: Regression in dump-emacs-portable

[Eli Zaretskii <eliz@gnu.org>]

> From: Lynn Winebarger <owinebar@gmail.com>
> Date: Fri, 17 Feb 2023 08:22:56 -0500
> Cc: emacs-devel@gnu.org
> 
> On Thu, Feb 16, 2023 at 6:45 PM Lynn Winebarger <owinebar@gmail.com> wrote:
> >
> > On Thu, Feb 16, 2023 at 10:34 AM Eli Zaretskii <eliz@gnu.org> wrote:
> > >
> > > > From: Lynn Winebarger <owinebar@gmail.com>
> > > > Date: Thu, 16 Feb 2023 10:05:00 -0500
> > > > Cc: emacs-devel <emacs-devel@gnu.org>
> > > >
> > > > I do see something in the redumped emacs that seems like a bug to me.  The process I use for creating the
> > > > dump uses the -Q flag.  But some of the settings I see in "emacs -Q --dump-file ..." are not the ones I see
> > > > with just "emacs -Q".  Some are pretty basic - menu-bar-mode, tool-bar-mode, global-font-lock-mode,
> > > > transient-mark-mode are all nil in the redumped process but not the baseline.
> > >
> > > That is exactly the problem with re-dumping: stuff that was
> > > initialized on the first start gets dumped, and then works differently
> > > when Emacs is restarted from the second dump.
> >
> > That appears to be a consequence of setting
> > custom-delayed-init-variables to t in startup, without saving a copy
> > to be restored by an after-pdump-load-hook.  Those modes have an
> > init-value expression involving "(not noninteractive)"  that is
> > evaluated during batch mode startup but not in the post-redump
> > startup.
> Something like this (untested):
> diff --git a/lisp/custom.el b/lisp/custom.el
> index 0522bdd447b..c16bc8f8560 100644
> --- a/lisp/custom.el
> +++ b/lisp/custom.el
> @@ -138,6 +138,19 @@ custom-delayed-init-variables
>    "List of variables whose initialization is pending until startup.
>  Once this list has been processed, this var is set to a non-list value.")
> 
> +(defvar custom-pdumped-delayed-init-variables nil
> +  "List of all variables whose initialization will be pending until
> +a startup following a redump.  This list is prepended to

I don't understand what will this solve.  Why does it matter when
exactly is a variable initialized, if in any case that will happen
before re-dumping?