Implement RFC#28: Add PartialOrd::partial_cmp

I ended up altering the semantics of Json's PartialOrd implementation.
It used to be the case that Null < Null, but I can't think of any reason
for an ordering other than the default one so I just switched it over to
using the derived implementation.

This also fixes broken `PartialOrd` implementations for `Vec` and
`TreeMap`.

RFC: 0028-partial-cmp

1 files changed, 2 insertions, 11 deletions

diff --git a/src/libcollections/dlist.rs b/src/libcollections/dlist.rs
index 7ea5c482e61..4114c8cb1c4 100644
--- a/src/libcollections/dlist.rs
+++ b/src/libcollections/dlist.rs
@@ -595,17 +595,8 @@ impl<A: PartialEq> PartialEq for DList<A> {
 }
 
 impl<A: PartialOrd> PartialOrd for DList<A> {
-    fn lt(&self, other: &DList<A>) -> bool {
-        iter::order::lt(self.iter(), other.iter())
-    }
-    fn le(&self, other: &DList<A>) -> bool {
-        iter::order::le(self.iter(), other.iter())
-    }
-    fn gt(&self, other: &DList<A>) -> bool {
-        iter::order::gt(self.iter(), other.iter())
-    }
-    fn ge(&self, other: &DList<A>) -> bool {
-        iter::order::ge(self.iter(), other.iter())
+    fn partial_cmp(&self, other: &DList<A>) -> Option<Ordering> {
+        iter::order::partial_cmp(self.iter(), other.iter())
     }
 }