By moving the implementation to qcore_mac.mm, and using a union for the object pointer, we can build qcore_mac.mm with -fobjc-weak to take advantage of the automatic weak-tracking. This allows us to drop the manual handling via ObjC associated objects, while also allowing non-Objective-C code to use QObjCWeakPointer. In particular we want to use it for QMacKeyValueObserver, which today runs the risk of removing the observation on an object that is long gone. Pick-to: 6.9 Change-Id: I5d605e5ac82b39223b246d6758d0da88a1702357 Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>