Bug#1024438: mutter: autopkgtest regression: segfault in workspace-basic.metatest

[Simon McVittie]

Control: severity -1 important

On Sun, 18 Dec 2022 at 15:58:06 +0000, Simon McVittie wrote:
> It looks as though the specific test-case that is segfaulting is
> consistently the one after stacking/unmaximize-new-size.metatest, which
> should be stacking/workspace-basic.metatest. That's consistent with
> Bernhard's backtrace, too.
...
> I'm testing a patch that should turn this from a segfault into a non-fatal
> warning.

It seems that running each test-case separately, instead of combining all
the test-cases into one run, works around this. That workaround is present
in the 43.2-3 upload (this change is
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2773 upstream).

I also applied a patch so that if the same error occurs for real users of
mutter, it will be a non-fatal critical warning rather than a crash
(https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2774 upstream).

The test failure continues to be a bug: please see upstream issue
report <https://gitlab.gnome.org/GNOME/mutter/-/issues/2559> if you are
interested in helping to resolve it. I think the solution is to make
switch_workspace() in src/compositor/plugins/default.c do something
reasonable if the window is being unmanaged, but I'm not sure what that
reasonable thing would be.

    smcv