>> I take it the refcount field's pointer is itself considered a weak >> reference, so the weak refcount starts +1 like the unowned refcount does? > > You need to do something to make sure the side allocation is not freed if the > object is live with no weak references to it. Biasing the weak refcount might > work. > > It might be more robust to do something else, though. Ideally an incorrect > weak reference decrement would deliberately log an underflow error and halt, > instead of quietly freeing the side allocation out from under a live object.
The backreference from the side allocation could be used to indicate the object's liveness. Require the object to null that pointer before it performs its weak release; then if the weak refcount goes to zero before the backreference is null, you've had an unbalanced release. -- Brent Royal-Gordon Architechies _______________________________________________ swift-dev mailing list swift-dev@swift.org https://lists.swift.org/mailman/listinfo/swift-dev
