--- /dev/null
+#![warn(clippy::invalid_atomic_ordering)]
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+fn main() {
+ // `compare_exchange` (not weak) testing
+ let x = AtomicUsize::new(0);
+
+ // Allowed ordering combos
+ let _ = x.compare_exchange(0, 0, Ordering::Relaxed, Ordering::Relaxed);
+ let _ = x.compare_exchange(0, 0, Ordering::Acquire, Ordering::Acquire);
+ let _ = x.compare_exchange(0, 0, Ordering::Acquire, Ordering::Relaxed);
+ let _ = x.compare_exchange(0, 0, Ordering::Release, Ordering::Relaxed);
+ let _ = x.compare_exchange(0, 0, Ordering::AcqRel, Ordering::Acquire);
+ let _ = x.compare_exchange(0, 0, Ordering::AcqRel, Ordering::Relaxed);
+ let _ = x.compare_exchange(0, 0, Ordering::SeqCst, Ordering::Relaxed);
+ let _ = x.compare_exchange(0, 0, Ordering::SeqCst, Ordering::Acquire);
+ let _ = x.compare_exchange(0, 0, Ordering::SeqCst, Ordering::SeqCst);
+
+ // AcqRel is always forbidden as a failure ordering
+ let _ = x.compare_exchange(0, 0, Ordering::Relaxed, Ordering::AcqRel);
+ let _ = x.compare_exchange(0, 0, Ordering::Acquire, Ordering::AcqRel);
+ let _ = x.compare_exchange(0, 0, Ordering::Release, Ordering::AcqRel);
+ let _ = x.compare_exchange(0, 0, Ordering::AcqRel, Ordering::AcqRel);
+ let _ = x.compare_exchange(0, 0, Ordering::SeqCst, Ordering::AcqRel);
+
+ // Release is always forbidden as a failure ordering
+ let _ = x.compare_exchange(0, 0, Ordering::Relaxed, Ordering::Release);
+ let _ = x.compare_exchange(0, 0, Ordering::Acquire, Ordering::Release);
+ let _ = x.compare_exchange(0, 0, Ordering::Release, Ordering::Release);
+ let _ = x.compare_exchange(0, 0, Ordering::AcqRel, Ordering::Release);
+ let _ = x.compare_exchange(0, 0, Ordering::SeqCst, Ordering::Release);
+
+ // Release success order forbids failure order of Acquire or SeqCst
+ let _ = x.compare_exchange(0, 0, Ordering::Release, Ordering::Acquire);
+ let _ = x.compare_exchange(0, 0, Ordering::Release, Ordering::SeqCst);
+
+ // Relaxed success order also forbids failure order of Acquire or SeqCst
+ let _ = x.compare_exchange(0, 0, Ordering::Relaxed, Ordering::SeqCst);
+ let _ = x.compare_exchange(0, 0, Ordering::Relaxed, Ordering::Acquire);
+
+ // Acquire/AcqRel forbids failure order of SeqCst
+ let _ = x.compare_exchange(0, 0, Ordering::Acquire, Ordering::SeqCst);
+ let _ = x.compare_exchange(0, 0, Ordering::AcqRel, Ordering::SeqCst);
+}