Derive more Eq implementations

Fixes #181.

src/components/gfx/geometry.rs

@@ -8,7 +8,7 @@ use geom::size::Size2D;
 
 use std::num::{NumCast, One, Zero};
 
-#[deriving(Clone)]
+#[deriving(Clone,Eq)]
 pub struct Au(i32);
 
 impl Add<Au,Au> for Au {
@@ -42,11 +42,6 @@ impl Ord for Au {
     fn gt(&self, other: &Au) -> bool { **self >  **other }
 }
 
-impl Eq for Au {
-    fn eq(&self, other: &Au) -> bool { **self == **other }
-    fn ne(&self, other: &Au) -> bool { **self != **other }
-}
-
 impl One for Au {
     fn one() -> Au { Au(1) }
 }

src/components/gfx/text/util.rs

@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#[deriving(Eq)]
 enum CompressionMode {
     CompressNone,
     CompressWhitespace,
@@ -9,21 +10,6 @@ enum CompressionMode {
     DiscardNewline
 }
 
-impl Eq for CompressionMode {
-    fn eq(&self, other: &CompressionMode) -> bool {
-        match (*self, *other) {
-            (CompressNone, CompressNone) => true,
-            (CompressWhitespace, CompressWhitespace) => true,
-            (CompressWhitespaceNewline, CompressWhitespaceNewline) => true,
-            (DiscardNewline, DiscardNewline) => true,
-            _ => false
-        }
-    }
-    fn ne(&self, other: &CompressionMode) -> bool {
-        !(*self).eq(other)
-    }
-}
-
 // ported from Gecko's nsTextFrameUtils::TransformText. 
 // 
 // High level TODOs:

src/components/script/dom/node.rs

@@ -28,29 +28,25 @@ use servo_util::tree::{TreeNode, TreeNodeRef, TreeUtils};
 
 /// A phantom type representing the script task's view of this node. Script is able to mutate
 /// nodes but may not access layout data.
+#[deriving(Eq)]
 pub struct ScriptView;
 
 /// A phantom type representing the layout task's view of the node. Layout is not allowed to mutate
 /// nodes but may access layout data.
+#[deriving(Eq)]
 pub struct LayoutView;
 
+// We shouldn't need Eq for ScriptView and LayoutView; see Rust #7671.
+
 /// This is what a Node looks like if you do not know what kind of node it is. To unpack it, use
 /// downcast().
 ///
 /// FIXME: This should be replaced with a trait once they can inherit from structs.
+#[deriving(Eq)]
 pub struct AbstractNode<View> {
     priv obj: *mut Node<View>,
 }
 
-impl<View> Eq for AbstractNode<View> {
-    fn eq(&self, other: &AbstractNode<View>) -> bool {
-        self.obj == other.obj
-    }
-    fn ne(&self, other: &AbstractNode<View>) -> bool {
-        self.obj != other.obj
-    }
-}
-
 /// An HTML node.
 ///
 /// `View` describes extra data associated with this node that this task has access to. For