Better bias selection for hints that prefix the type

Co-Authored-By: Antonio Scandurra <antonio@zed.dev>

crates/sum_tree/src/sum_tree.rs

@@ -95,35 +95,13 @@ impl<D> fmt::Debug for End<D> {
     }
 }
 
-#[derive(Copy, Clone, Eq, PartialEq, Debug, Hash)]
+#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug, Hash, Default)]
 pub enum Bias {
+    #[default]
     Left,
     Right,
 }
 
-impl Default for Bias {
-    fn default() -> Self {
-        Bias::Left
-    }
-}
-
-impl PartialOrd for Bias {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for Bias {
-    fn cmp(&self, other: &Self) -> Ordering {
-        match (self, other) {
-            (Self::Left, Self::Left) => Ordering::Equal,
-            (Self::Left, Self::Right) => Ordering::Less,
-            (Self::Right, Self::Right) => Ordering::Equal,
-            (Self::Right, Self::Left) => Ordering::Greater,
-        }
-    }
-}
-
 #[derive(Debug, Clone)]
 pub struct SumTree<T: Item>(Arc<Node<T>>);