1 files changed, 34 insertions, 0 deletions
diff --git a/tests/ui/union/union-generic-rpass.rs b/tests/ui/union/union-generic-rpass.rs
new file mode 100644
index 00000000000..25f1f5050f9
--- /dev/null
+++ b/tests/ui/union/union-generic-rpass.rs
@@ -0,0 +1,34 @@
+// run-pass
+// revisions: mirunsafeck thirunsafeck
+// [thirunsafeck]compile-flags: -Z thir-unsafeck
+
+#![allow(dead_code)]
+
+use std::mem::ManuallyDrop;
+
+union MaybeItem<T: Iterator> {
+    elem: ManuallyDrop<T::Item>,
+    none: (),
+}
+
+union U<A, B> where A: Copy, B: Copy {
+    a: A,
+    b: B,
+}
+
+unsafe fn union_transmute<A, B>(a: A) -> B where A: Copy, B: Copy {
+    U { a }.b
+}
+
+fn main() {
+    unsafe {
+        let b = union_transmute::<(u8, u8), u16>((1, 1));
+        assert_eq!(b, (1 << 8) + 1);
+
+        let v: Vec<u8> = vec![1, 2, 3];
+        let mut i = v.iter();
+        i.next();
+        let mi = MaybeItem::<std::slice::Iter<_>> { elem: ManuallyDrop::new(i.next().unwrap()) };
+        assert_eq!(**mi.elem, 2);
+    }
+}