From ec870b7986e8294b700a0d576e0179babb512f7c Mon Sep 17 00:00:00 2001
From: Sampson Wong <sampson.wong123@gmail.com>
Date: Mon, 17 Nov 2014 16:44:01 +1100
Subject: [PATCH] implement Deref for Box.

fixes #18624
---
 src/liballoc/boxed.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 26f8522e1c18a..dfb8683a4368d 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -18,6 +18,7 @@ use core::fmt;
 use core::intrinsics;
 use core::kinds::Sized;
 use core::mem;
+use core::ops::{Deref, DerefMut};
 use core::option::Option;
 use core::raw::TraitObject;
 use core::result::{Ok, Err, Result};
@@ -52,6 +53,14 @@ impl<T> Default for Box<[T]> {
     fn default() -> Box<[T]> { box [] }
 }
 
+impl<Sized? T> Deref<T> for Box<T> {
+    fn deref(&self) -> &T { &**self }
+}
+
+impl<Sized? T> DerefMut<T> for Box<T> {
+    fn deref_mut(&mut self) -> &mut T { &mut **self }
+}
+
 #[unstable]
 impl<T: Clone> Clone for Box<T> {
     /// Returns a copy of the owned box.
@@ -183,4 +192,11 @@ mod test {
         let s = format!("{}", b);
         assert_eq!(s.as_slice(), "&Any");
     }
+
+    #[test]
+    fn auto_deref() {
+    	fn test<U: Deref<int> >(_: U) {}
+	let foo = box 1;
+	test(foo);
+    }
 }