add some run-pass tests for NLL showing that things work as expected

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

@@ -0,0 +1,31 @@
+// 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)]
+
+use std::collections::HashMap;
+
+fn get_default(map: &mut HashMap<usize, String>, key: usize) -> &mut String {
+    match map.get_mut(&key) {
+        Some(value) => value,
+        None => {
+            map.insert(key, "".to_string());
+            map.get_mut(&key).unwrap()
+        }
+    }
+}
+
+fn main() {
+    let map = &mut HashMap::new();
+    map.insert(22, format!("Hello, world"));
+    map.insert(44, format!("Goodbye, world"));
+    assert_eq!(&*get_default(map, 22), "Hello, world");
+    assert_eq!(&*get_default(map, 66), "");
+}

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

@@ -0,0 +1,37 @@
+// 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)]
+
+use std::collections::HashMap;
+
+fn process_or_insert_default(map: &mut HashMap<usize, String>, key: usize) {
+    match map.get_mut(&key) {
+        Some(value) => {
+            process(value);
+        }
+        None => {
+            map.insert(key, "".to_string());
+        }
+    }
+}
+
+fn process(x: &str) {
+    assert_eq!(x, "Hello, world");
+}
+
+fn main() {
+    let map = &mut HashMap::new();
+    map.insert(22, format!("Hello, world"));
+    map.insert(44, format!("Goodbye, world"));
+    process_or_insert_default(map, 22);
+    process_or_insert_default(map, 66);
+    assert_eq!(map[&66], "");
+}

src/test/run-pass/nll/rc-loop.rs

@@ -0,0 +1,40 @@
+// 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.
+
+// 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.
+
+#![feature(match_default_bindings)]
+#![feature(nll)]
+
+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));
+}
+