Make empty arrays Copy

Author: tbu-

src/libcore/array.rs

@@ -216,7 +216,7 @@ macro_rules! array_impl_clone {
     };
     {$n:expr,} => {
         #[stable(feature = "rust1", since = "1.0.0")]
-        impl<T: Clone> Clone for [T; 0] {
+        impl<T> Clone for [T; 0] {
             fn clone(&self) -> [T; 0] {
                 []
             }

src/librustc/middle/traits/select.rs

@@ -1720,9 +1720,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 }
             }
 
-            ty::TyArray(element_ty, _) => {
+            ty::TyArray(element_ty, n) => {
                 // [T; n]
                 match bound {
+                    ty::BoundCopy if n == 0 => ok_if(Vec::new()),
                     ty::BoundCopy => ok_if(vec![element_ty]),
                     ty::BoundSized => ok_if(Vec::new()),
                     ty::BoundSync | ty::BoundSend => {