The implementation is silently discarding this anyway, and
g_object_unref() is using atomic operations. So this should be safe.

Having this here triggers -Wdiscarded-qualifiers when g_clear_pointer()
is fixed to use __typeof__().

This reverts merge request !165

The implementation is silently discarding this anyway, and
g_object_unref() is using atomic operations. So this should be safe.

Having this here triggers -Wdiscarded-qualifiers when g_clear_pointer()
is fixed to use __typeof__().

Switch the check which tests whether the object has been finalised from
being a use-after-free, to using a weak pointer which is nullified on
finalisation.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Weak-pointers are currently lacking g_set_object() & g_clear_object()
helpers equivalent. New functions (and macros, both are provided) are
convenient in many case, especially for the property's notify-on-set
pattern:

  if (g_set_weak_pointer (...))
    g_object_notify (...)

Inspired by Christian Hergert's original implementation for
gnome-builder.

https://bugzilla.gnome.org/show_bug.cgi?id=749527

Along the same lines as g_clear_object(), g_set_object() is a
convenience function to update a GObject pointer, handling reference
counting transparently and correctly.

Specifically, it handles the case where a pointer is set to its current
value. If handled naïvely, that could result in the object instance
being finalised. In the following code, that happens when
(my_obj == new_value) and the object has a single reference:
    g_clear_object (&my_obj);
    my_obj = g_object_ref (new_value);

It also simplifies boilerplate code such as set_property()
implementations, which are otherwise long and boring.

Test cases included.

https://bugzilla.gnome.org/show_bug.cgi?id=741589

Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().

Remove those uses, as they are no longer required.

https://bugzilla.gnome.org/show_bug.cgi?id=686161

These are non-threaded, but the do test dup and destroy somewhat.

https://bugzilla.gnome.org/show_bug.cgi?id=682849