- After GC, the live weak pointer list may have forwarding pointers
- on it, because a weak pointer object was evacuated after being
- moved to the live weak pointer list. We remove those forwarding
- pointers here.
-
- Also, we don't consider weak pointer objects to be reachable, but
- we must nevertheless consider them to be "live" and retain them.
- Therefore any weak pointer objects which haven't as yet been
- evacuated need to be evacuated now.
+ Evacuate every weak pointer object on the weak_ptr_list, and update
+ the link fields.
+
+ ToDo: with a lot of weak pointers, this will be expensive. We
+ should have a per-GC weak pointer list, just like threads.