Re: [PATCH] Project out of sources compilation

[Eli Zaretskii <eliz@gnu.org>]

> From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
> Cc: rms@gnu.org, dmitry@gutov.dev, emacs-devel@gnu.org
> Date: Thu, 04 Apr 2024 23:16:29 +0300
> 
> Can we please agree that generating .elc files in the
> build dir rather than in tree allows to avoid a number of problems? 
> Please note that this has nothing to do with `.elc` files being put in
> tarballs, because for that to work you could just build "in-tree" as
> usual.  Putting `.elc` files into build dir (which may be in-tree or
> out) and allowing Emacs to take those into account is just
> simplification in how things work.

As I wrote up-thread, I have no objections for adding this to Emacs,
but it is not as trivial as it seems, because Emacs needs more files
than just *.elc to run, and some of those other files are in the
source tree when Emacs runs uninstalled (example: the images in
etc/images).  So adding this mode of running Emacs would need some
changes to the C startup code, not just to Makefile's.  Also, if you
edit *.el files in the source directory, the *.eln files produced from
the *.el files before the edits will no longer be loaded by Emacs
(because they don't match the corresponding *.el files); if we want to
fix that as well, we'd need much more serious changes.