Stabilize cmp

This patch marks `PartialEq`, `Eq`, `PartialOrd`, and `Ord` as
`#[stable]`, as well as the majorify of manual implementaitons of these
traits. The traits match the [reform
RFC](https://github.com/rust-lang/rfcs/pull/439).

Along the way, two changes are made:

* The recently-added type parameters for `Ord` and `Eq` are
  removed. These were mistakenly added while adding them to `PartialOrd`
  and `PartialEq`, but they don't make sense given the laws that are
  required for (and use cases for) `Ord` and `Eq`.

* More explicit laws are added for `PartialEq` and `PartialOrd`,
  connecting them to their associated mathematical concepts.

In the future, many of the impls should be generalized; see
since generalizing later is not a breaking change.

[breaking-change]

3 files changed, 13 insertions, 9 deletions

diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 21c47cdf3d7..f6f83f22f92 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -458,7 +458,7 @@ impl<T: Sync + Send> Drop for Weak<T> {
     }
 }
 
-#[unstable = "waiting on PartialEq"]
+#[stable]
 impl<T: PartialEq> PartialEq for Arc<T> {
     /// Equality for two `Arc<T>`s.
     ///
@@ -490,7 +490,7 @@ impl<T: PartialEq> PartialEq for Arc<T> {
     /// ```
     fn ne(&self, other: &Arc<T>) -> bool { *(*self) != *(*other) }
 }
-#[unstable = "waiting on PartialOrd"]
+#[stable]
 impl<T: PartialOrd> PartialOrd for Arc<T> {
     /// Partial comparison for two `Arc<T>`s.
     ///
@@ -569,11 +569,11 @@ impl<T: PartialOrd> PartialOrd for Arc<T> {
     /// ```
     fn ge(&self, other: &Arc<T>) -> bool { *(*self) >= *(*other) }
 }
-#[unstable = "waiting on Ord"]
+#[stable]
 impl<T: Ord> Ord for Arc<T> {
     fn cmp(&self, other: &Arc<T>) -> Ordering { (**self).cmp(&**other) }
 }
-#[unstable = "waiting on Eq"]
+#[stable]
 impl<T: Eq> Eq for Arc<T> {}
 
 impl<T: fmt::Show> fmt::Show for Arc<T> {
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 3c6b2d2cbc0..74f0599e486 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -72,12 +72,14 @@ impl<T: Clone> Clone for Box<T> {
     }
 }
 
+#[stable]
 impl<Sized? T: PartialEq> PartialEq for Box<T> {
     #[inline]
     fn eq(&self, other: &Box<T>) -> bool { PartialEq::eq(&**self, &**other) }
     #[inline]
     fn ne(&self, other: &Box<T>) -> bool { PartialEq::ne(&**self, &**other) }
 }
+#[stable]
 impl<Sized? T: PartialOrd> PartialOrd for Box<T> {
     #[inline]
     fn partial_cmp(&self, other: &Box<T>) -> Option<Ordering> {
@@ -92,12 +94,14 @@ impl<Sized? T: PartialOrd> PartialOrd for Box<T> {
     #[inline]
     fn gt(&self, other: &Box<T>) -> bool { PartialOrd::gt(&**self, &**other) }
 }
+#[stable]
 impl<Sized? T: Ord> Ord for Box<T> {
     #[inline]
     fn cmp(&self, other: &Box<T>) -> Ordering {
         Ord::cmp(&**self, &**other)
     }
-}
+
+#[stable]}
 impl<Sized? T: Eq> Eq for Box<T> {}
 
 impl<S: hash::Writer, Sized? T: Hash<S>> Hash<S> for Box<T> {
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 214fae02ce2..75d4342083b 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -452,7 +452,7 @@ impl<T: Default> Default for Rc<T> {
     }
 }
 
-#[unstable = "PartialEq is unstable."]
+#[stable]
 impl<T: PartialEq> PartialEq for Rc<T> {
     /// Equality for two `Rc<T>`s.
     ///
@@ -487,10 +487,10 @@ impl<T: PartialEq> PartialEq for Rc<T> {
     fn ne(&self, other: &Rc<T>) -> bool { **self != **other }
 }
 
-#[unstable = "Eq is unstable."]
+#[stable]
 impl<T: Eq> Eq for Rc<T> {}
 
-#[unstable = "PartialOrd is unstable."]
+#[stable]
 impl<T: PartialOrd> PartialOrd for Rc<T> {
     /// Partial comparison for two `Rc<T>`s.
     ///
@@ -575,7 +575,7 @@ impl<T: PartialOrd> PartialOrd for Rc<T> {
     fn ge(&self, other: &Rc<T>) -> bool { **self >= **other }
 }
 
-#[unstable = "Ord is unstable."]
+#[stable]
 impl<T: Ord> Ord for Rc<T> {
     /// Comparison for two `Rc<T>`s.
     ///