[gtk+/gtk-3-22] Fixed: If can’t add child, don’t add to child info

[Daniel Boles <dboles src gnome org>]

commit 81b7f76cb825a4bbb59c759b0f117b76155e5df8
Author: Daniel Boles <dboles src gnome org>
Date:   Thu Oct 12 14:05:09 2017 +0100

    Fixed: If can’t add child, don’t add to child info
    
    If the call to set_parent() failed, we were still adding the child to
    the internal list of children, despite that it was not really added.
    That meant we could later try to do invalid stuff with that non-child.
    
    Fix that by asserting and giving up if the child that the user is
    attempting to add is already parented.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=701296

 gtk/gtkfixed.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkfixed.c b/gtk/gtkfixed.c
index 4fa237e..70d31f6 100644
--- a/gtk/gtkfixed.c
+++ b/gtk/gtkfixed.c
@@ -235,6 +235,7 @@ gtk_fixed_put (GtkFixed  *fixed,
 
   g_return_if_fail (GTK_IS_FIXED (fixed));
   g_return_if_fail (GTK_IS_WIDGET (widget));
+  g_return_if_fail (_gtk_widget_get_parent (widget) == NULL);
 
   priv = fixed->priv;