bug#48117: 28.0.50; Update of loaddefs.el during normal build is unreliable

[Eli Zaretskii]

> Date: Sat, 01 May 2021 09:20:51 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: rgm@gnu.org, 48117@debbugs.gnu.org
> 
> > Your proposal would produce marginally better results for a 
> > significantly longer build time, so I don't think it's a net win.
> 
> If ldefs-boot.el is updated, say, once a week, this would force the 
> regeneration of the loaddefs files at most once a week.  Wouldn't that be 
> a reasonable compromise?

Compromise between which alternatives?

The "marginally better" results in your proposal are that if someone
updates from Git when he/she is in the middle of some development,
then loaddefs.el are made up-to-date immediately, as opposed to
_maybe_ waiting for the next update of ldefs-boot.el.  (I say "maybe"
because in general loaddefs.el _are_ updated as part of routine
builds, just not 100% reliably so.)

> On my computer, regenerating the loaddefs files takes about 10
> seconds, or ~3% of the time of a make bootstrap.

Keep in mind that some people use less powerful machines.  And the
bootstrap time is not relevant, because loaddefs.el is completely
regenerated during bootstrap anyway.  The time that is relevant is the
time of just "make", and that is usually quite short, even on slow
machines.