1 files changed, 28 insertions, 0 deletions
diff --git a/src/test/ui/nll/rc-loop.rs b/src/test/ui/nll/rc-loop.rs
new file mode 100644
index 000000000..e59303d1f
--- /dev/null
+++ b/src/test/ui/nll/rc-loop.rs
@@ -0,0 +1,28 @@
+// run-pass
+
+// A test for something that NLL enables. It sometimes happens that
+// the `while let` pattern makes some borrows from a variable (in this
+// case, `x`) that you need in order to compute the next value for
+// `x`.  The lexical checker makes this very painful. The NLL checker
+// does not.
+
+use std::rc::Rc;
+
+#[derive(Debug, PartialEq, Eq)]
+enum Foo {
+    Base(usize),
+    Next(Rc<Foo>),
+}
+
+fn find_base(mut x: Rc<Foo>) -> Rc<Foo> {
+    while let Foo::Next(n) = &*x {
+        x = n.clone();
+    }
+    x
+}
+
+fn main() {
+    let chain = Rc::new(Foo::Next(Rc::new(Foo::Base(44))));
+    let base = find_base(chain);
+    assert_eq!(&*base, &Foo::Base(44));
+}