NLL test for mutating &mut references

src/test/run-pass/nll/mutating_references.rs

@@ -0,0 +1,34 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(nll)]
+
+struct List<T> {
+    value: T,
+    next: Option<Box<List<T>>>,
+}
+
+fn to_refs<T>(mut list: &mut List<T>) -> Vec<&mut T> {
+    let mut result = vec![];
+    loop {
+        result.push(&mut list.value);
+        if let Some(n) = list.next.as_mut() {
+            list = n;
+        } else {
+            return result;
+        }
+    }
+}
+
+fn main() {
+    let mut list = List { value: 1, next: None };
+    let vec = to_refs(&mut list);
+    assert_eq!(vec![&mut 1], vec);
+}