Bug 762747 – traceback: cannot create instance of abstract (non-instantiatable) type GDM_TYPE_XDMCP_DISPLAY

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Bug 762747 - traceback: cannot create instance of abstract (non-instantiatable) type GDM_TYPE_XDMCP_DISPLAY


Summary:	traceback: cannot create instance of abstract (non-instantiatable) type GDM_T...


Status:	RESOLVED DUPLICATE of bug 757714

Product:	gdm
Classification:	Core
Component:	general
Version:	3.18.x
Hardware:	Other Linux

Importance:	Normal normal
Target Milestone:	---
Assigned To:	GDM maintainers
QA Contact:	GDM maintainers

URL:
Whiteboard:

Depends on:
Blocks:

Reported:	2016-02-26 17:38 UTC by Jim Minter
Modified:	2016-02-26 17:53 UTC

See Also:
GNOME target:	---
GNOME version:	---

Description Jim Minter 2016-02-26 17:38:05 UTC

When enabling XDMCP in GDM in latest F23 ([xdmcp] Enable=true) in /etc/gdm/custom.conf and attaching to GDM, I immediately get the traceback below.

It looks like g_object_new is indicating "cannot create instance of abstract (non-instantiatable) type" for GDM_TYPE_XDMCP_DISPLAY - surely that's not expected?

# rpm -q gdm
gdm-3.18.2-2.fc23.i686

(gdb) bt

+ Trace 236005

#0 _g_log_abort
at gmessages.c line 324
#1 g_logv
#2 g_log
#3 g_type_create_instance
at gtype.c line 1816
#4 g_object_constructor
at gobject.c line 2064
#5 gdm_display_constructor
at gdm-display.c line 1110
#6 g_object_new_with_custom_constructor
at gobject.c line 1697
#7 g_object_new_internal
at gobject.c line 1777
#8 g_object_new_valist
at gobject.c line 2038
#9 g_object_new
at gobject.c line 1622
#10 gdm_xdmcp_display_new
at gdm-xdmcp-display.c line 276
#11 gdm_xdmcp_display_create
at gdm-xdmcp-display-factory.c line 2149
#12 gdm_xdmcp_handle_request
at gdm-xdmcp-display-factory.c line 2390
#13 decode_packet
at gdm-xdmcp-display-factory.c line 2995
#14 g_io_unix_dispatch
at giounix.c line 165
#15 g_main_dispatch
at gmain.c line 3154
#16 g_main_context_dispatch
at gmain.c line 3769
#17 g_main_context_iterate
at gmain.c line 3840
#18 g_main_loop_run
at gmain.c line 4034
#19 main
at main.c line 404

Comment 1 Jim Minter 2016-02-26 17:50:38 UTC

Hmm, simply doing the following seems to have a positive effect, but I'm in the dark here...

diff -uNr gdm-3.18.2/daemon/gdm-xdmcp-display.c gdm-3.18.2a/daemon/gdm-xdmcp-display.c
--- gdm-3.18.2/daemon/gdm-xdmcp-display.c	2016-02-26 17:43:45.368000000 +0000
+++ gdm-3.18.2a/daemon/gdm-xdmcp-display.c	2015-11-17 17:14:16.000000000 +0000
@@ -66,7 +66,7 @@
 static void     gdm_xdmcp_display_class_init    (GdmXdmcpDisplayClass *klass);
 static void     gdm_xdmcp_display_init          (GdmXdmcpDisplay      *xdmcp_display);
 
-G_DEFINE_ABSTRACT_TYPE (GdmXdmcpDisplay, gdm_xdmcp_display, GDM_TYPE_DISPLAY)
+G_DEFINE_TYPE (GdmXdmcpDisplay, gdm_xdmcp_display, GDM_TYPE_DISPLAY)
 
 gint32
 gdm_xdmcp_display_get_session_number (GdmXdmcpDisplay *display)

Comment 2 Jim Minter 2016-02-26 17:53:24 UTC

Sigh...

*** This bug has been marked as a duplicate of bug 757714 ***