Re: HELP: GLib-GObject-WARNING **: instance of invalid non-instantiatable type `(null)'

[David Nečas (Yeti) <yeti physics muni cz>]

On Wed, May 23, 2007 at 12:16:51PM +0200, Guenther Meyer wrote:
> I'm working on a gtk-project for some month; I already solved a lot of 
> problems by myself, but I'm still learning.
> But now I have a problem, where I can't find any solution:
> 
> In my application there's is one window, when I'm closing it, I always can see 
> the following messages:
> 
> GLib-GObject-WARNING **: instance of invalid non-instantiatable type `(null)'
> 
> GLib-GObject-CRITICAL **: g_signal_emit_valist: assertion 
> `G_TYPE_CHECK_INSTANCE (instance)' failed
> 
> and sometimes the application segfaults after this.
> 
> The interesting thing is, that there are other windows, that use exactly the 
> same code, but they work without any problems...
> 
> any hints or tips?

Use valgrind.

And use gdb, since you get segfaults, have you tried to at
least print backtrace to see where it crashes?

  gdb program core.12345
  backtrace

You can also make GLib abort (and dump core) on CRITICAL or
WARNING messages using g_log_set_always_fatal() or more
flexibily by setting the G_DEBUG environment variable (see
GLib reference documentation).

The first two points apply generally, not just to Gtk+
programs.

Yeti

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