bug#48994: 28.0.50; [PATCH] 28.0.50; Native compilation unnecessarily recompiles .eln (macOS)

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 14 Jun 2021 19:32:36 +0100
> From: Alan Third <alan@idiocy.org>
> Cc: 48994@debbugs.gnu.org, mjbauer95@gmail.com, akrl@sdf.org
> 
> > > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=47558#44
> > 
> > Hmm... that problem was solved, though?  So how come it comes up once
> > again?
> 
> It was solved for the .app use case, perhaps that broke the Unix-style
> install case?

Could very well be, see below.

> I have to admit that I don't really understand this and have a very
> limited understanding of how the makefiles build the .app or not.

My primary worry is not the Makefiles, it's what the installed Emacs
does upon startup to find its requisite files.

> >   . the Emacs binary
> 
> Emacs.app/Contents/MacOS/Emacs
> 
> (This is different on GNUstep builds. I think it's
> Emacs.app/Contents/Emacs.)
> 
> >   . the .pdmp file
> 
> The same location as the binary. That was my change and it was done
> that way because I don't really understand any of this but that
> happened to work.

If the pdumper file is near the binary, I think Emacs will decide it's
running uninstalled, and will look for the *.eln files in
../native-lisp relative to where the binary lives.  Which is not
necessarily what you want, AFAIU.

> >   . the auxiliary executables (hexl, movemail)
> 
> I believe they're in Emacs.app/Contents/MacOS/libexec.
> 
> (Again, this is different on GNUstep.)
> 
> >   . the *.eln files
> 
> Emacs.app/Contents/Resources/native-elisp, or something. I'm not at a
> Mac to check right now, but definitely under Resources.

OK, please tell after you find out.

> > Also, I understand that the "normal" Unix-style install has the usual
> > tree hierarchy rooted at /usr or /usr/local, and there everything
> > "just works"?

You didn't answer this one.  Are we using the Unix-style hierarchy in
this case, i.e.:

  . Emacs binary in /usr/bin
  . the .pdmp file in /usr/libexec/emacs/VERSION/ARCHITECTURE
  . the *eln files in /usr/lib/emacs/VERSION/native-lisp

?

> > If so, when (at configure time, at installation time,
> > at some other time?) is the decision made whether the install will be
> > one or the other?
> 
> I believe there's a ./configure flag. But like I said before, for the
> other paths there's a run-time check, so I'm not sure how it all ties
> together.

Which run-time check did you have in mind?