Upstream bug is https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4597

** Bug watch added: gitlab.gnome.org/GNOME/gnome-shell/-/issues #4597
   https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4597

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https://bugs.launchpad.net/bugs/1937958

Title:
  gnome-shell gdb instructions cause immediate "Oh no" crash

Status in gnome-shell package in Ubuntu:
  Incomplete

Bug description:
  I wanted to report a gnome-shell bug with a backtrace, so tried to use
  the instructions in

     https://wiki.gnome.org/Projects/GnomeShell/Debugging

  which say to do the following in an ssh login or separate VT:

    gnome_session=$(pgrep -u $USER gnome-session)
    eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep 
DISPLAY)
    eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep 
XAUTHORITY)
    eval export $(sed 's/\o000/\n/g;' < /proc/$gnome_session/environ | grep 
DBUS_SESSION_BUS_ADDRESS)
    gdb
    ...etc...

  However three problems came up, two minor (wrong instructions), the
  other major:

  (1) There is more than one gnome-session process, and so the shell
  variable $gnome_session gets set to a list of several PIDs, which in
  turn causes syntax errors when using the expression
  "/proc/$gnome_session/environ".

  In Ubuntu 21.04 I have three gnome-session processes immediately after
  rebooting and logging in (I have auto-login enabled, so the login
  happens by itself, in case that matters):

  $ ps -F $(pgrep -u $USER gnome-session|perl -p -e 's/(\d+)/-p $1/')
  UID          PID    PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
  jima        9743    9725  0 55216 16084   2 13:41 tty3     00:00:00 
/usr/libexec/gnome-session-binary --systemd --session=ubuntu
  jima        9828    8066  0 24031  6148   8 13:41 ?        00:00:00 
/usr/libexec/gnome-session-ctl --monitor
  jima        9838    8066  0 129272 18176  7 13:41 ?        00:00:00 
/usr/libexec/gnome-session-binary --systemd-service --session=ubuntu

  (2) The instructions specify this gdb command:

    call gjs_dumpstack ()

  However that results in an error and the call is not made:
  'gjs_dumpstack' has unknown return type; cast the call to its declared
  return type

  (3) Most importantly, a crash:  Immediately upon starting the new
  gnome-shell process (with option --replace) a white screen appears
  with "Oh No... something went wrong..." forcing me log out.

  The crash happens whether using an independent VT or an ssh login.

  Afterwards I typed Control-C to get control in gdb, and produced the
  attached backtraces but they don't seem useful (see attached
  typescript file).

  /var/syslog might be useful.  I will attach the portion beginning just
  before starting the new gnome-shell

  The attached typescript file shows what I did to circumvent the buggy
  instructions at https://wiki.gnome.org/Projects/GnomeShell/Debugging

  P.S. The original crash I wanted to report was that opening any .jpg
  in gimp and selecting part of the image and then doing Select->Invert
  instantly freezes the system.  The only recovery is to use a separate
  VT to kill the gimp process, after which gnome-shell restarts.  A
  system error dialog appears saying gnome-session [correction: gnome-
  shell] got a segfault somewhere; thus the desire to get a backtrace.
  But this bug report is _not_ about that bug, but is about how using
  the debug instructions in the wiki are incorrect and when fixed seem
  to cause a crash on their own.

  ProblemType: Bug
  DistroRelease: Ubuntu 21.04
  Package: gnome-shell 3.38.4-1ubuntu3~21.04.1
  ProcVersionSignature: Ubuntu 5.11.0-25.27-generic 5.11.22
  Uname: Linux 5.11.0-25-generic x86_64
  ApportVersion: 2.20.11-0ubuntu65.1
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: GNOME
  Date: Sun Jul 25 13:41:54 2021
  DisplayManager: gdm3
  InstallationDate: Installed on 2021-07-20 (5 days ago)
  InstallationMedia: Ubuntu-Server 21.04 "Hirsute Hippo" - Release amd64 
(20210421)
  RelatedPackageVersions: mutter-common 3.38.4-1ubuntu2
  SourcePackage: gnome-shell
  UpgradeStatus: No upgrade log present (probably fresh install)

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