rollup merge of #20723: pnkfelix/feature-gate-box-syntax

Conflicts:
	src/compiletest/compiletest.rs
	src/libcollections/lib.rs
	src/libserialize/lib.rs
	src/libsyntax/feature_gate.rs

src/liballoc/boxed.rs

@@ -49,6 +49,15 @@ pub static HEAP: () = ();
 #[stable]
 pub struct Box<T>(Unique<T>);
 
+#[unstable]
+impl<T> Box<T> {
+    /// Moves `x` into a freshly allocated box on the global exchange heap.
+    #[unstable]
+    pub fn new(x: T) -> Box<T> {
+        box x
+    }
+}
+
 #[stable]
 impl<T: Default> Default for Box<T> {
     #[stable]
@@ -186,27 +195,27 @@ impl<T: ?Sized> DerefMut for Box<T> {
 mod test {
     #[test]
     fn test_owned_clone() {
-        let a = box 5i;
+        let a = Box::new(5i);
         let b: Box<int> = a.clone();
         assert!(a == b);
     }
 
     #[test]
     fn any_move() {
-        let a = box 8u as Box<Any>;
-        let b = box Test as Box<Any>;
+        let a = Box::new(8u) as Box<Any>;
+        let b = Box::new(Test) as Box<Any>;
 
         match a.downcast::<uint>() {
-            Ok(a) => { assert!(a == box 8u); }
+            Ok(a) => { assert!(a == Box::new(8u)); }
             Err(..) => panic!()
         }
         match b.downcast::<Test>() {
-            Ok(a) => { assert!(a == box Test); }
+            Ok(a) => { assert!(a == Box::new(Test)); }
             Err(..) => panic!()
         }
 
-        let a = box 8u as Box<Any>;
-        let b = box Test as Box<Any>;
+        let a = Box::new(8u) as Box<Any>;
+        let b = Box::new(Test) as Box<Any>;
 
         assert!(a.downcast::<Box<Test>>().is_err());
         assert!(b.downcast::<Box<uint>>().is_err());
@@ -214,8 +223,8 @@ mod test {
 
     #[test]
     fn test_show() {
-        let a = box 8u as Box<Any>;
-        let b = box Test as Box<Any>;
+        let a = Box::new(8u) as Box<Any>;
+        let b = Box::new(Test) as Box<Any>;
         let a_str = a.to_str();
         let b_str = b.to_str();
         assert_eq!(a_str, "Box<Any>");
@@ -232,6 +241,6 @@ mod test {
     #[test]
     fn deref() {
         fn homura<T: Deref<Target=i32>>(_: T) { }
-        homura(box 765i32);
+        homura(Box::new(765i32));
     }
 }