1 files changed, 37 insertions, 0 deletions
diff --git a/tests/ui/union/union-drop-assign.rs b/tests/ui/union/union-drop-assign.rs
new file mode 100644
index 000000000..215666bdd
--- /dev/null
+++ b/tests/ui/union/union-drop-assign.rs
@@ -0,0 +1,37 @@
+// run-pass
+#![allow(unused_assignments)]
+
+// Drop works for union itself.
+
+use std::mem::ManuallyDrop;
+
+struct S;
+
+union U {
+    a: ManuallyDrop<S>
+}
+
+impl Drop for S {
+    fn drop(&mut self) {
+        unsafe { CHECK += 10; }
+    }
+}
+
+impl Drop for U {
+    fn drop(&mut self) {
+        unsafe { CHECK += 1; }
+    }
+}
+
+static mut CHECK: u8 = 0;
+
+fn main() {
+    unsafe {
+        let mut u = U { a: ManuallyDrop::new(S) };
+        assert_eq!(CHECK, 0);
+        u = U { a: ManuallyDrop::new(S) };
+        assert_eq!(CHECK, 1); // union itself is assigned, union is dropped, field is not dropped
+        *u.a = S;
+        assert_eq!(CHECK, 11); // union field is assigned, field is dropped
+    }
+}