bug#44128: [feature/native-comp] When invoking a symlink to the 'emacs' binary Emacs fails to start

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 16 Apr 2021 18:08:00 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: psainty@orcon.net.nz, akrl@sdf.org, 44128@debbugs.gnu.org, eli@gnu.org
> 
> > From: Jonas Bernoulli <jonas@bernoul.li>
> > Date: Fri, 16 Apr 2021 15:21:47 +0200
> > Cc: 44128@debbugs.gnu.org, eli@gnu.org
> > 
> > Andrea Corallo <akrl@sdf.org> writes:
> > 
> > > I've pushed 0c1fc9d581 that seams to work for me, please have a try.
> > 
> > Unfortunately this still doesn't work (as of f9c1008ced):
> > 
> >   $ emacs
> >   emacs: could not resolve realpath of "emacs": No such file or directory
> >   $ which emacs
> >   /usr/local/bin/emacs
> >   $ ls -l /usr/local/bin/emacs
> >   lrwxrwxrwx 1 root staff 55 Apr 16 14:51 /usr/local/bin/emacs -> /home/jonas/git/src/emacs/feature
> > 
> > But this works:
> > 
> >   $ /home/jonas/git/src/emacs/feature/native-comp/src/emacs
> > 
> > And so does:
> > 
> >   $ cat /usr/local/bin/emacs
> >   #!/bin/sh
> >   /home/jonas/git/src/emacs/feature/native-comp/src/emacs "$@"
> >   $ emacs
> 
> Thanks, I think I understand the issues, and I'm working on a fix.

Please try the latest native-comp branch.  If it still doesn't solve
the problem with installing Emacs via symlinks, or if there are some
adverse side-effects of the changes I made, please report the details.

In a nutshell, Emacs should now decide where to look for its pdumper
file and where to look for the *.eln files in a synchronized manner.
I hope I got all the varieties of the symlinks involved correctly (but
I couldn't test all the possible variants, only some of them).

Please be sure to test both installed and uninstalled binaries, and
please verify that comp-eln-load-path has the right value after Emacs
loads in both cases (the last element of the list should in each case
reflect where the *.eln files will be looked for).

TIA