use std::sync::{Arc, Mutex};

    use std::sync::atomic::AtomicBool;
    use std::sync::atomic::Ordering::SeqCst;
    use std::sync::Arc;

        struct HasDrop(Box<Arc<Mutex<bool>>>);

        struct HasDrop(Arc<AtomicBool>);

                let mut has_dropped = self.0.lock().unwrap();
                assert!(!*has_dropped);
                *has_dropped = true;

                let has_dropped = self.0.swap(true, SeqCst);
                assert!(!has_dropped);

        let has_dropped = Arc::new(Mutex::new(false));

        let has_dropped = Arc::new(AtomicBool::new(false));

        drop(Error::from(HasDrop(Box::new(has_dropped.clone()))));

        drop(Error::from(HasDrop(has_dropped.clone())));

        assert!(*has_dropped.lock().unwrap());

        assert!(has_dropped.load(SeqCst));