Update needless_borrowed_ref lint example.

clippy_tests/examples/needless_borrowed_ref.rs

@@ -2,8 +2,36 @@
 #![plugin(clippy)]
 
 #[warn(needless_borrowed_reference)]
+#[allow(unused_variables)]
 fn main() {
     let mut v = Vec::<String>::new();
     let _ = v.iter_mut().filter(|&ref a| a.is_empty());
+    //                            ^ should be linted
+
+    let mut var = 5;
+    let thingy = Some(&mut var);
+    if let Some(&mut ref v) = thingy {
+        //          ^ should *not* be linted
+        // here, var is borrowed as immutable.
+        // can't do that:
+        //*v = 10;
+    }
+}
+
+#[allow(dead_code)]
+enum Animal {
+    Cat(u64),
+    Dog(u64),
+}
+
+#[allow(unused_variables)]
+#[allow(dead_code)]
+fn foo(a: &Animal, b: &Animal) {
+    match (a, b) {
+        (&Animal::Cat(v), &ref k) | (&ref k, &Animal::Cat(v)) => (), // lifetime mismatch error if there is no '&ref'
+        //                  ^    and   ^ should *not* be linted
+        (&Animal::Dog(ref a), &Animal::Dog(_)) => ()
+        //              ^ should *not* be linted
+    }
 }