fix core for targets with max-atomic-width = 0

closes #45802

diff --git a/src/libcore/sync/atomic.rs b/src/libcore/sync/atomic.rs
index cd3dd9ce1399e2e2f604549b425f8be0df078a2e..b7cf6d778a2f9d4298af22a2fe04641ff8536d98 100644 (file)
--- a/src/libcore/sync/atomic.rs
+++ b/src/libcore/sync/atomic.rs
@@ -927,6 +927,7 @@ pub fn compare_exchange_weak(&self,
     }
 }
 
+#[cfg(target_has_atomic = "ptr")]
 #[stable(feature = "atomic_from", since = "1.23.0")]
 impl<T> From<*mut T> for AtomicPtr<T> {
     #[inline]