Re: Regression in dump-emacs-portable

[Lynn Winebarger <owinebar@gmail.com>]

On Fri, Feb 17, 2023 at 9:31 AM Eli Zaretskii <eliz@gnu.org> wrote:
> 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?

You're right with respect to the current definitions of
custom-initialize-* functions that will only set variables if they are
unbound.
The docstring for custom-initialize-delay is:
  "Delay initialization of SYMBOL to the next Emacs start.
This is used in files that are preloaded (or for autoloaded
variables), so that the initialization is done in the run-time
context rather than the build-time context.  This also has the
side-effect that the (delayed) initialization is performed with
the :set function."
But "so the initialization is done in the run-time context" and "to
the *next* Emacs start" (emphasis mine) are contradictory unless
dumping can only happen once.    The first sentence should be "Ensure
SYMBOL is set to initial-value at Emacs startup".  Otherwise, the
"initialization" will only reflect the value of the customization when
it was first set, regardless of whether that value reflects the
*current* run-time context due to redumping.  In particular, currently
redumping has to happen in a noninteractive context, so redumping of a
customization with an initialization expression referencing the value
of 'noninteractive will not be correct when it is later used in an
interactive session.  Also, any customization variables introduced
after a redump that are supposed to be initialized by
#'custom-initialize-delay will not be initialized on the next startup,
since custom-delayed-init-variables is already set to t in the dump.
The current implementation only works for customization variables
defined in the initial dump.
I'll take a shot at a more thorough rewrite of the customization
system to properly support redumping this weekend and send another
patch.

Lynn