1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ui/borrowck/borrowck-union-borrow-nested.rs b/tests/ui/borrowck/borrowck-union-borrow-nested.rs
new file mode 100644
index 000000000..b3a6670fa
--- /dev/null
+++ b/tests/ui/borrowck/borrowck-union-borrow-nested.rs
@@ -0,0 +1,31 @@
+#[derive(Clone, Copy)]
+struct S {
+    a: u8,
+    b: u16,
+}
+
+#[derive(Clone, Copy)]
+union U {
+    s: S,
+    c: u32,
+}
+
+fn main() {
+    unsafe {
+        {
+            let mut u = U { s: S { a: 0, b: 1 } };
+            let ra = &mut u.s.a;
+            let b = u.s.b; // OK
+            ra.use_mut();
+        }
+        {
+            let mut u = U { s: S { a: 0, b: 1 } };
+            let ra = &mut u.s.a;
+            let b = u.c; //~ ERROR cannot use `u.c` because it was mutably borrowed
+            ra.use_mut();
+        }
+    }
+}
+
+trait Fake { fn use_mut(&mut self) { } fn use_ref(&self) { }  }
+impl<T> Fake for T { }