Move sys::refcount to managed::refcount

More progress on #2240

src/libstd/managed.rs

@@ -17,6 +17,13 @@ use ptr::to_unsafe_ptr;
 pub static RC_MANAGED_UNIQUE : uint = (-2) as uint;
 pub static RC_IMMORTAL : uint = 0x77777777;
 
+/// Returns the refcount of a shared box (as just before calling this)
+#[inline]
+pub fn refcount<T>(t: @T) -> uint {
+    use unstable::raw::Repr;
+    unsafe { (*t.repr()).ref_count }
+}
+
 /// Determine if two shared boxes point to the same object
 #[inline]
 pub fn ptr_eq<T>(a: @T, b: @T) -> bool {

src/libstd/sys.rs

@@ -13,22 +13,12 @@
 #[allow(missing_doc)];
 
 use c_str::ToCStr;
-use cast;
 use libc::size_t;
 use libc;
 use repr;
 use rt::task;
 use str;
 
-/// Returns the refcount of a shared box (as just before calling this)
-#[inline]
-pub fn refcount<T>(t: @T) -> uint {
-    unsafe {
-        let ref_ptr: *uint = cast::transmute_copy(&t);
-        *ref_ptr - 1
-    }
-}
-
 pub fn log_str<T>(t: &T) -> ~str {
     use rt::io;
     use rt::io::Decorator;