bug#46790: 28.0.50; [native-comp] Emacs doesn't start when run from a symlink

[Phil Sainty]

I've compiled the feature/native-comp branch and it starts if I run
the real path to the executable; but if I run it from a symlink it
fails:

$ ls -l /home/phil/bin/emacs-native-comp
lrwxrwxrwx 1 phil phil 48 Apr 14 00:01 /home/phil/bin/emacs-native-comp -> 
/home/phil/emacs/native-comp/usr/local/bin/emacs

$ emacs-native-comp -Q
emacs: 
/home/phil/bin/../native-lisp/28.0.50-abd7aa58/preloaded/window-0d1b8b93-513ac8ca.eln:
 cannot open shared object file: No such file or directory


Looking relative to the symlink itself is clearly wrong.  Something
like `file-truename' should surely be utilised here.  (GNU readlink
with the -m option does much the same thing, if that's at all helpful.)

I'm sending to what looks like a duplicate bug, although my case seems
like a more standard configuration -- I'm not passing a custom 'bindir'
to 'make install'; I'm simply using the normal 'configure --prefix=...'
(see below).


-Phil



In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 
1.15.10, Xaw3d scroll bars)
 of 2021-04-13 built on shodan
Repository revision: 8ed46b7646de7166aa8bbd3b5d29a4947316c900
Repository branch: feature/native-comp
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Ubuntu 18.04.5 LTS

Configured using:
 'configure --prefix=/home/phil/emacs/native-comp/usr/local
 --with-x-toolkit=lucid --without-sound --with-native-compilation'

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG
THREADS TIFF TOOLKIT_SCROLL_BARS X11 XAW3D XDBE XIM XPM LUCID ZLIB

Important settings:
  value of $LANG: en_NZ.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source eieio eieio-core eieio-loaddefs
password-cache json map text-property-search time-date mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils comp
comp-cstr warnings subr-x rx cl-seq cl-macs cl-extra help-mode seq
byte-opt gv cl-loaddefs cl-lib bytecomp byte-compile cconv iso-transl
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo x-toolkit x multi-tty make-network-process nativecomp emacs)

Memory information:
((conses 16 92899 8806)
 (symbols 48 7808 1)
 (strings 32 24363 4126)
 (string-bytes 1 830720)
 (vectors 16 17056)
 (vector-slots 8 316265 21888)
 (floats 8 37 35)
 (intervals 56 225 0)
 (buffers 992 12))