Big applications can be complicated and have some complex states. A destructor calls a function that calls a function that checks if an object exist. By chance

Big applications can be complicated and have some complex states. A destructor calls a function that calls a function that checks if an object exist. By chance with libstdc++, the half destroyed object was marked as "non existent", but not with libc++. Destructor usually call function to unregister themselves from some other places, or free other owned ressources.