zephyr: work: Add Drop implementation to futures Work

This will catch instances of the work itself being stopped before the
Future running in it has terminated.  Not ideal, as it should be
permissible to drop it.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

zephyr/src/work.rs

@@ -410,6 +410,17 @@ pub mod futures {
         }
     }
 
+    impl<F: Future + Send> Drop for Work<F> {
+        fn drop(&mut self) {
+            // Ideally, we would actually try to free this, but as a sanity check, make sure the
+            // strong count of the waker itself is 1, meaning we are the only holder.
+            let count = Arc::strong_count(&self.waker);
+            if count != 1 {
+                panic!("Workwaker has leaked within Work");
+            }
+        }
+    }
+
     /// Waker for a work.
     ///
     /// This is the information needed for the waker to be able to run the thread, as well as