gnome-session 49 disabled x11 support by default

[bobby285271]

What Happened?

Since GNOME/gnome-session@21f10a9 the x11 support is disabled by default in gnome-session, which means gnome-session-x11@.target is no longer installed. This will result in:

machine # [   49.275528] .gnome-session-[1362]: Starting GNOME session target: gnome-session-x11@pantheon.target
machine # [   49.525328] traps: .gnome-session-[1362] trap int3 ip:7f6363e22fef sp:7ffcb69ecf30 error:0 in libglib-2.0.so.0.8600.0[6efef,7f6363dd7000+aa000]
machine # [   49.283250] .gnome-session-[1362]: Failed to start unit gnome-session-x11@pantheon.target: GDBus.Error:org.freedesktop.systemd1.NoSuchUnit: Unit gnome-session-x11@pantheon.target not found.
machine # [   49.304958] systemd-coredump[1378]: Process 1362 (.gnome-session-) of user 1000 terminated abnormally with signal 5/TRAP, processing...
machine # [   49.315215] systemd[1]: Created slice Slice /system/systemd-coredump.
machine # [   49.320931] systemd[1]: Started Process Core Dump (PID 1378/UID 0).
machine # [   49.488194] systemd-coredump[1379]: Process 1362 (.gnome-session-) of user 1000 dumped core.

I believe the plan is to eventually land gnome-session!99 in GNOME 50. As a downstream packager I am interested in what is the preferred way to handle this right now (and maybe in elementary OS 9). I see 3 options:

1. Start forking gnome-session (ugh).
2. Drop the X11 session.
3. -Dx11=true, or ship a custom gnome-session-x11@pantheon.target either here or in our packaging, similar to gnome-flashback (probably won't work with gnome-session 50).

---

I am typing this on NixOS Pantheon Wayland with gnome-session 48, so the session does function here :-)

screenshot

cc NixOS/nixpkgs#440720

Steps to Reproduce

1. Bump stuff to GNOME 49
2. Start Pantheon

Expected Behavior

All provided Pantheon sessions works on NixOS.

OS Version

Other Linux

OS Architecture

amd64 (on most hardwares)

Session Type

Classic Session (X11, This is the default)

Software Version

Latest release (I have run all updates)

[danirabbit]

I imagine we'll drop the X11 session for OS 9 unless someone is really invested in making it work. But so far I don't think I've seen interest in that 😅 So for now we could add a build flag to build without it, I think. Does that sound okay to you?

[bobby285271]

Yes that sounds good!