Remove some warnings and make tests pass.

Author: eholk

src/libcore/arc.rs

@@ -28,7 +28,6 @@ resource arc_destruct<T>(data: *libc::c_void) {
     unsafe {
         let data: ~arc_data<T> = unsafe::reinterpret_cast(data);
         let new_count = rustrt::rust_atomic_decrement(&mut data.count);
-        let data_ptr : *() = unsafe::reinterpret_cast(data);
         assert new_count >= 0;
         if new_count == 0 {
             // drop glue takes over.
@@ -70,7 +69,6 @@ fn clone<T: const>(rc: &arc<T>) -> arc<T> {
     unsafe {
         let ptr: ~arc_data<T> = unsafe::reinterpret_cast(**rc);
         let new_count = rustrt::rust_atomic_increment(&mut ptr.count);
-        let data_ptr : *() = unsafe::reinterpret_cast(ptr);
         assert new_count >= 2;
         unsafe::forget(ptr);
     }
@@ -97,7 +95,6 @@ impl methods<T: send> for exclusive<T> {
             // this makes me nervous...
             let ptr: ~arc_data<ex_data<T>> = unsafe::reinterpret_cast(*self);
             let new_count = rustrt::rust_atomic_increment(&mut ptr.count);
-            let data_ptr : *() = unsafe::reinterpret_cast(ptr);
             assert new_count > 1;
             unsafe::forget(ptr);
         }

src/libcore/vec.rs

@@ -2193,13 +2193,6 @@ mod tests {
         assert addr == addr_imm;
     }
 
-    #[test]
-    fn test_unshift() {
-        let mut x = [1, 2, 3];
-        unshift(x, 0);
-        assert x == [0, 1, 2, 3];
-    }
-
     #[test]
     fn test_capacity() {
         let mut v = [0u64];