Nixpkgs: gnome3 logout button doesn't show

[worldofpeace]

Describe the bug
With gnome3 and gdm you won't see the logout button in the session.

To Reproduce
Steps to reproduce the behavior:

1. Login to gnome session
2. Run:

nix-shell -p gobject-introspection -p gdm -p gjs --run 'gjs -c "print(imports.gi.Gdm.get_session_ids().length)"'

This will return 0 and the logout button won't be visible per https://github.com/GNOME/gnome-shell/blob/b2d6c11ec39042855910f36d59e0789e16593fb9/js/misc/systemActions.js#L394

Expected behavior
You can see the logout button with multiple sessions (the default gnome).

Meaning

nix-shell -p gobject-introspection -p gdm -p gjs --run 'gjs -c "print(imports.gi.Gdm.get_session_ids().length)"'

will return 2 in the default gnome install.

Should we create a regression test for this?

Additional context
This was discovered when looking into https://github.com/NixOS/nixpkgs/issues/84634.

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module: gnome3

[worldofpeace]

Should we create a regression test for this?

Actually, the issue is the gnome test doesn't verify you can see things like the logout button and the panel.

[monoidal]

I get infinite recursion on commit d74573d8 on nixos-20.03 branch with nixos-rebuild switch:

while evaluating the attribute 'system.activationScripts.script' at /home/g/nixpkgs/nixos/modules/system/activation/activation-script.nix:68:9:
while evaluating 'textClosureMap' at /home/g/nixpkgs/lib/strings-with-deps.nix:70:35, called from /home/g/nixpkgs/nixos/modules/system/activation/activation-script.nix:89:18:
while evaluating 'id' at /home/g/nixpkgs/lib/trivial.nix:14:5, called from undefined position:
while evaluating the attribute 'text' at /home/g/nixpkgs/nixos/modules/system/activation/activation-script.nix:9:5:
while evaluating the attribute 'text' at /home/g/nixpkgs/lib/strings-with-deps.nix:77:38:
while evaluating the attribute 'sources' of the derivation 'etc' at /home/g/nixpkgs/nixos/modules/system/etc/etc.nix:12:5:
while evaluating anonymous function at /home/g/nixpkgs/nixos/modules/system/etc/etc.nix:20:20, called from undefined position:
while evaluating the attribute 'source' at undefined position:
while evaluating anonymous function at /home/g/nixpkgs/lib/modules.nix:84:45, called from undefined position:
while evaluating the attribute 'value' at /home/g/nixpkgs/lib/modules.nix:379:9:
while evaluating the option `environment.etc.dbus-1.source':
while evaluating the attribute 'mergedValue' at /home/g/nixpkgs/lib/modules.nix:411:5:
while evaluating anonymous function at /home/g/nixpkgs/lib/modules.nix:413:22, called from /home/g/nixpkgs/lib/modules.nix:413:9:
while evaluating 'check' at /home/g/nixpkgs/lib/types.nix:251:15, called from /home/g/nixpkgs/lib/modules.nix:414:14:
while evaluating the attribute 'serviceDirectories' of the derivation 'dbus-1' at /home/g/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating anonymous function at /home/g/nixpkgs/lib/types.nix:263:14, called from undefined position:
while evaluating the attribute 'value' at /home/g/nixpkgs/lib/modules.nix:425:27:
while evaluating anonymous function at /home/g/nixpkgs/lib/modules.nix:413:22, called from /home/g/nixpkgs/lib/modules.nix:413:9:
while evaluating 'check' at /home/g/nixpkgs/lib/types.nix:251:15, called from /home/g/nixpkgs/lib/modules.nix:414:14:
while evaluating the attribute 'passAsFile' of the derivation 'system-path' at /home/g/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating the attribute 'buildCommand' of the derivation 'desktops' at /home/g/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating 'concatMapStrings' at /home/g/nixpkgs/lib/strings.nix:31:25, called from /home/g/nixpkgs/nixos/modules/services/x11/display-managers/default.nix:124:9:
while evaluating anonymous function at /home/g/nixpkgs/nixos/modules/services/x11/display-managers/default.nix:124:27, called from undefined position:
while evaluating the attribute 'text' of the derivation 'mate-xsession' at /home/g/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating the attribute 'text' of the derivation 'xsession' at /home/g/nixpkgs/pkgs/build-support/trivial-builders.nix:7:14:
while evaluating the attribute 'start' at /home/g/nixpkgs/nixos/modules/services/x11/desktop-managers/default.nix:73:11:
while evaluating the attribute 'start' at /home/g/nixpkgs/nixos/modules/services/x11/desktop-managers/mate.nix:50:7:
infinite recursion encountered, at undefined position

The error disappears if I remove services.xserver.desktopManager.mate.enable = true; or use the previous commit.

[jtojnar]

I reverted the commit on 20.03, seems to fix the issue. 20.09 and master do not seem to be affected so I did not analyse the issue, especially since this 20.03 is so close to EOL.

[pickfire]

Same for lxqt.

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/infinite-recursion-on-nixos-rebuilt-related-to-lxqt/9551/5

[jtojnar]

It has been reverted in 2a4607f4422 (master), 9ca3b745648 (release-20.09) and 8fa9a8aa02298d738d552cc36af2e816cf03badb (release-20.03). See https://github.com/NixOS/nixpkgs/pull/100112#issuecomment-708908610 for details.

[malbarbo]

The "Switch user" button doesn't show also.