Re: native compilation units

[Eli Zaretskii <eliz@gnu.org>]

> From: Lynn Winebarger <owinebar@gmail.com>
> Date: Mon, 6 Jun 2022 12:23:49 -0400
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>, Andrea Corallo <akrl@sdf.org>, emacs-devel@gnu.org
> 
>  Of course, there is: that function is what is invoked when building a
>  release tarball, where the *.elc files are already present.  See
>  lisp/Makefile.in.
> 
> That's what I expected was the case, but the question is whether it "should"
> check for those .elc files and create them only if they do not exist, as opposed
> to batch-byte+native-compile, which creates both unconditionally.  Or perhaps
> just note the possible hiccup in the docstring for batch-native-compile?

You are describing a different function.  batch-native-compile was
explicitly written to support the build of a release tarball, where
the *.elc files are always present, and regenerating them is just a
waste of cycles, and also runs the risk of creating a .elc file that
is not fully functional, due to some peculiarity of the platform or
the build environment.

> However, since the eln file can be generated without the elc file, it also begs the question
> of why the use of the eln file is conditioned on the existence of the elc file in the
> first place.  Are there situations where the eln file would be incorrect to use 
> without the byte-compiled file in place?

Andrea was asked this question several times and explained his design,
you can find it in the archives.  Basically, native compilation is
driven by byte compilation, and is a kind of side effect of it.