static void
infpy_dealloc (PyObject *obj)
{
  /* This dealloc is for a special case.  Normally inferiors are added
     to our internal inferior list by the inferior add observers.
     Even when the GDB inferior is removed with remove-inferior, and
     the corresponding call to py_free_inferior is invoked, the Python
     inferior object is not deleted, but now represents an invalid
     inferior (the Python object still has a ref count of 1, being a
     member of the inferior list.  We cannot delete this inferior
     object, even though it points to a defunct inferior as the user
     might reference it.  This is legal.  In the case of a GDB that is not
     running any "real" inferiors, there is still one dummy inferior.
     This dummy inferior is never notified to observers so we do not
     track it in our internal inferior list.  The problem lies when
     the user does: py print gdb.current_inferior ().  This create a
     new Python inferior, calls set_inferior_data to attach this
     inferior to this Python Object.  However, immediately after
     printing the reference count for this object reaches zero, and
     the object garbage collected.  However the reference set in
     set_inferior_data still points to this now defunct object.  As
     the model for inferiors is one inferior object per inferior, any
     existing inferior object is returned by inferior_data.  In this
     case it will now be the bogus garbage collected inferior object.
     In all cases but the dummy inferior this will not happen as there
     is a reference in the internal inferior list.  */

  inferior_object *inf_obj = (inferior_object *) obj;
  struct inferior *inf = inf_obj->inferior;
  if (! inf)
    return;

  set_inferior_data (inf, infpy_inf_data_key, NULL);
}