Bug#956219: Error out when DISPLAY is unset

[Alberto Garcia]

On Sat, Apr 25, 2020 at 10:17:47AM +0200, Laurent Bigonville wrote:
> I'm reopening this as yelp still FTBFS with 2.28.2 with the same
> error, was the patch cherry-picked?

It was, but the problem seems to be different this time (a null
pointer):

process:35799): Gtk-CRITICAL **: 13:40:20.270: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed

** (process:35799): WARNING **: 13:40:20.271: Unable to connect to dbus: Cannot autolaunch D-Bus without X11 $DISPLAY
Unable to init server: Could not connect: Connection refused
Segmentation fault

Thread 1 "libyelp-scan" received signal SIGSEGV, Segmentation fault.
0x00007ffff335cbd4 in wpe_renderer_backend_egl_destroy (backend=0x0) at ./src/renderer-backend-egl.c:54
54          backend->base.interface->destroy(backend->base.interface_data);
(gdb) bt
#0  0x00007ffff335cbd4 in wpe_renderer_backend_egl_destroy (backend=0x0) at ./src/renderer-backend-egl.c:54
#1  0x00007ffff63bc8bb in WebCore::PlatformDisplayLibWPE::~PlatformDisplayLibWPE() ()
    at ../Source/WebCore/platform/graphics/libwpe/PlatformDisplayLibWPE.cpp:66
#2  0x00007ffff63bc8d9 in WebCore::PlatformDisplayLibWPE::~PlatformDisplayLibWPE() ()
    at ../Source/WebCore/platform/graphics/libwpe/PlatformDisplayLibWPE.cpp:67
#3  0x00007ffff7c59e27 in __run_exit_handlers
    (status=0, listp=0x7ffff7dd8718 <__exit_funcs>, run_list_atexit=run_list_atexit at entry=true, run_dtors=run_dtors at entry=true)
    at exit.c:108
#4  0x00007ffff7c59fda in __GI_exit (status=<optimized out>) at exit.c:139
#5  0x00007ffff7c42e12 in __libc_start_main (main=
    0x555555556480 <main>, argc=1, argv=0x7fffffffdd78, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffdd68) at ../csu/libc-start.c:342
#6  0x0000555555557b7a in _start () at libyelp-scan.c:1025

This looks like the WPE backend (which WebKitGTK uses), but from the
backtrace I can't quite tell yet where exactly the root of the problem
is. We'll investigate it and make sure that yelp builds after we have
fixed it.

Thanks for the report and sorry for the annoyance !

Berto