Re: build broken: no defun org-float-time. Who's guilty, and what does he propose?

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: Ken Raeburn <raeburn@raeburn.org>, acm@muc.de, jan.h.d@swipnet.se,
>         joakim@verona.se, emacs-devel@gnu.org
> Date: Tue, 08 Sep 2009 13:01:21 -0400
> 
> Note that a basic hypothesis here, is that "make bootstrap" is not
> a good solution, so any solution that ends recompiling similar amounts
> of code is not good either.  But if you look in detail, you'll see that
> only bootstrap does it really right: the byte-compiler is
> a prerequisitie of all elc files, and the byte-compiler itself uses
> potentially any code in loadup.el (and then some), so any change to
> a preloaded file should fundamentally require recompiling all
> Lisp files.

I don't think this is quite that bad.  There's a similar issue in many
GNU packages with config.h files produced by a configure script, and
the solution there is to output the new version into a temporary file
and use move-if-change to replace the original file.  We could do the
same with bytecomp.elc, and that would solve the above problem.

>   When byte-compiling elc files with a preexisting emacs-bootstrap
>   binary, re-load all the files that were preloaded but that have been
>   changed since building emacs-bootstrap, before doing the actual
>   recompilation (i.e. when starting emacs-bootstrap, check the
>   load-history to see if any of those files have changed and reload them
>   if needed).

Sounds like a good plan to me.