auto merge of #15030 : sfackler/rust/partial-cmp, r=huonw

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`.

# Note
This isn't ready to merge yet since libcore tests are broken as you end up with 2 versions of `Option`. The rest should be reviewable though.

RFC: 0028-partial-cmp

2 files changed, 10 insertions, 0 deletions

diff --git a/src/liballoc/owned.rs b/src/liballoc/owned.rs
index 33afa806f4e..addec396bbe 100644
--- a/src/liballoc/owned.rs
+++ b/src/liballoc/owned.rs
@@ -18,6 +18,7 @@ use core::fmt;
 use core::intrinsics;
 use core::kinds::Send;
 use core::mem;
+use core::option::Option;
 use core::raw::TraitObject;
 use core::result::{Ok, Err, Result};
 
@@ -65,6 +66,10 @@ impl<T:PartialEq> PartialEq for Box<T> {
 }
 impl<T:PartialOrd> PartialOrd for Box<T> {
     #[inline]
+    fn partial_cmp(&self, other: &Box<T>) -> Option<Ordering> {
+        (**self).partial_cmp(*other)
+    }
+    #[inline]
     fn lt(&self, other: &Box<T>) -> bool { *(*self) < *(*other) }
     #[inline]
     fn le(&self, other: &Box<T>) -> bool { *(*self) <= *(*other) }
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index e3127030842..83cc4a0b662 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -171,6 +171,11 @@ impl<T: Eq> Eq for Rc<T> {}
 
 impl<T: PartialOrd> PartialOrd for Rc<T> {
     #[inline(always)]
+    fn partial_cmp(&self, other: &Rc<T>) -> Option<Ordering> {
+        (**self).partial_cmp(&**other)
+    }
+
+    #[inline(always)]
     fn lt(&self, other: &Rc<T>) -> bool { **self < **other }
 
     #[inline(always)]