> Since rust follows RAII, any and all resources allocated in the context should be deallocated when their destructor (the drop trait) is called. The unfortunate exception to this are resources which require an async call to deallocate properly. Though this can be worked around and there is work being done to fix this properly.

Yeah as I said async does not, in fact, "provide easily cancellable execution patterns".

only if the resources are just used within this task. If an async function at some point in time generates another task (or even spawns a thread!) that can not be synchronously cancelled then it might outlive the destructor and thereby the async task. It's therefore nowhere near guaranteed that every Future can just be dropped to stop an action in a side-effect free fashion.