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

[Gregory Heytings]

> > > 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?

I see at least the following possible alternatives:

- the current situation, which you describe in your original post, in 
which the loaddefs files need to be regenerated manually (inconvenient)

- regenerating the loaddefs files for each make invocation (inefficient)

- copying the ldefs-boot.el onto loaddefs.el when it is more recent (which 
IIUC could lose local additions to loaddefs.el)

- automatically regenerating the loaddefs files when ldefs-boot.el is more 
recent than loaddefs.el (which I understand could be a bit slow)

- issue only a warning when make is invoked and ldefs-boot.el is more 
recent than loaddefs.el (and perhaps add a autoloads or loaddefs target to 
the main Makefile)