1 files changed, 96 insertions, 0 deletions
diff --git a/src/test/ui/borrowck/borrowck-union-borrow.rs b/src/test/ui/borrowck/borrowck-union-borrow.rs
new file mode 100644
index 000000000..f01915398
--- /dev/null
+++ b/src/test/ui/borrowck/borrowck-union-borrow.rs
@@ -0,0 +1,96 @@
+#[derive(Clone, Copy)]
+union U {
+    a: u8,
+    b: u64,
+}
+
+fn main() {
+    unsafe {
+        let mut u = U { b: 0 };
+        // Imm borrow, same field
+        {
+            let ra = &u.a;
+            let ra2 = &u.a; // OK
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            let a = u.a; // OK
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
+            drop(ra);
+        }
+        // Imm borrow, other field
+        {
+            let ra = &u.a;
+            let rb = &u.b; // OK
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            let b = u.b; // OK
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because it is also borrowed as immutable (via `u.a`)
+            drop(ra);
+        }
+        {
+            let ra = &u.a;
+            u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
+            drop(ra);
+        }
+        // Mut borrow, same field
+        {
+            let rma = &mut u.a;
+            let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
+            drop(rma);
+        }
+        {
+            let ra = &mut u.a;
+            let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
+            drop(ra);
+        }
+        {
+            let rma = &mut u.a;
+            let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
+            drop(rma);
+        }
+        {
+            let rma = &mut u.a;
+            u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
+            drop(rma);
+        }
+        // Mut borrow, other field
+        {
+            let rma = &mut u.a;
+            let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because it is also borrowed as mutable (via `u.a`)
+            drop(rma);
+        }
+        {
+            let ra = &mut u.a;
+            let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
+
+            drop(ra);
+        }
+        {
+            let rma = &mut u.a;
+            let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
+            drop(rma);
+        }
+        {
+            let rma = &mut u.a;
+            u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
+            drop(rma);
+        }
+    }
+}