Derive PartialOrd, Ord and Hash for bitflags types.

In order to prevent users from having to manually implement Hash and Ord for
bitflags types, this commit derives these traits automatically.

This breaks code that has manually implemented any of these traits for types
created by the bitflags! macro. Change this code by removing implementations
of these traits.

[breaking-change]

src/libstd/bitflags.rs

@@ -113,7 +113,7 @@ macro_rules! bitflags(
     ($(#[$attr:meta])* flags $BitFlags:ident: $T:ty {
         $($(#[$Flag_attr:meta])* static $Flag:ident = $value:expr),+
     }) => (
-        #[deriving(PartialEq, Eq, Clone)]
+        #[deriving(PartialEq, Eq, Clone, PartialOrd, Ord, Hash)]
         $(#[$attr])*
         pub struct $BitFlags {
             bits: $T,
@@ -220,6 +220,7 @@ macro_rules! bitflags(
 
 #[cfg(test)]
 mod tests {
+    use hash;
     use option::{Some, None};
     use ops::{BitOr, BitAnd, Sub, Not};
 
@@ -336,4 +337,42 @@ mod tests {
         assert!((e1 - e2) == FlagA);     // set difference
         assert!(!e2 == FlagA);           // set complement
     }
+
+    #[test]
+    fn test_lt() {
+        let mut a = Flags::empty();
+        let mut b = Flags::empty();
+
+        assert!(!(a < b) && !(b < a));
+        b = FlagB;
+        assert!(a < b);
+        a = FlagC;
+        assert!(!(a < b) && b < a);
+        b = FlagC | FlagB;
+        assert!(a < b);
+    }
+
+    #[test]
+    fn test_ord() {
+        let mut a = Flags::empty();
+        let mut b = Flags::empty();
+
+        assert!(a <= b && a >= b);
+        a = FlagA;
+        assert!(a > b && a >= b);
+        assert!(b < a && b <= a);
+        b = FlagB;
+        assert!(b > a && b >= a);
+        assert!(a < b && a <= b);
+    }
+
+    #[test]
+    fn test_hash() {
+      let mut x = Flags::empty();
+      let mut y = Flags::empty();
+      assert!(hash::hash(&x) == hash::hash(&y));
+      x = Flags::all();
+      y = FlagABC;
+      assert!(hash::hash(&x) == hash::hash(&y));
+    }
 }

src/libstd/io/mod.rs

@@ -1795,7 +1795,6 @@ pub struct UnstableFileStat {
 bitflags!(
     #[doc="A set of permissions for a file or directory is represented
 by a set of flags which are or'd together."]
-    #[deriving(Hash)]
     #[deriving(Show)]
     flags FilePermission: u32 {
         static UserRead     = 0o400,