Using [kde-unstable] packages for Arch Linux. Even with new user and so fresh config files and caches, plasmashell crashes on startup but only for the plasmawayland session. sudo journalctl -i | grep libwayland shows loads of segfaults for plasmashell, krunner, and kwin-wayland e.g. plasmashell[1126]: segfault at 0 ip 00007f5ae8de7289 sp 00007ffc6fab7010 error 4 in libwayland-client.so.0.3.0
Just to add some context: the [kde-unstable] repo contains also Qt 5.8 RC. There are reports from other users that can reproduce the issue with Qt 5.8RC + Plasma 5.8.5, so the problem seems to be with Qt 5.8. Will try to provide a useful backtrace with debug symbols.
needs backtrace to be useful
I am seeing something very similar (black screen with mouse pointer, sometimes some of my autostart programs (e.g. owncloud sync) start, if I close those, right-click or press the krunner keyboard shortcut krunner crashes and ~1min later plasmashell as well), so I think it's the same problem. I recompiled qt5-base, qt5-wayland (5.8 RC) and plasma-workspace (5.8.95) with debug symbols. For krunner I got this stacktrace from journalctl (demangled with c++filt): Stack trace of thread 1254: #0 0x00007f61295a304f raise (libc.so.6) #1 0x00007f612d8ba7d6 KCrash::defaultCrashHandler(int) (libKF5Crash.so.5) #2 0x00007f61295a30b0 __restore_rt (libc.so.6) #3 0x00007f6127f26289 wl_proxy_marshal (libwayland-client.so.0) #4 0x00007f6119e3d259 QtWayland::wl_surface::destroy() (libQt5WaylandClient.so.5) #5 0x00007f6119e23bfb QtWaylandClient::QWaylandWindow::reset() #6 0x00007f6119e26ff8 QtWaylandClient::QWaylandWindow::setVisible(bool) #7 0x00007f612a4756cc QWindow::setVisible(bool) (libQt5Gui.so.5) #8 0x0000000000406baa main (krunner) #9 0x00007f6129590291 __libc_start_main (libc.so.6) #10 0x0000000000406cda _start (krunner) for plasmashell only this: Stack trace of thread 1256: #0 0x00007f15fa16004f n/a (n/a) (libwayland-client is provided by the wayland 1.12.0-1 package)
https://codereview.qt-project.org/#/c/181146/