std: add a twos-complement fn back to ints and uints

src/libstd/num/int_macros.rs

@@ -419,7 +419,10 @@ impl Integer for $T {
     fn is_odd(&self) -> bool { !self.is_even() }
 }
 
-impl Bitwise for $T {}
+impl Bitwise for $T {
+    #[inline]
+    fn compl(&self) -> $T { -1 as $T ^ *self }
+}
 
 #[cfg(not(test))]
 impl BitOr<$T,$T> for $T {

src/libstd/num/num.rs

@@ -244,7 +244,10 @@ pub trait Bitwise: Not<Self>
                  + BitOr<Self,Self>
                  + BitXor<Self,Self>
                  + Shl<Self,Self>
-                 + Shr<Self,Self> {}
+                 + Shr<Self,Self> {
+    // Computes the bitwise complement
+    fn compl(&self) -> Self;
+}
 
 pub trait BitCount {
     fn population_count(&self) -> Self;

src/libstd/num/uint_macros.rs

@@ -281,7 +281,10 @@ impl Integer for $T {
     fn is_odd(&self) -> bool { !self.is_even() }
 }
 
-impl Bitwise for $T {}
+impl Bitwise for $T {
+    #[inline]
+    fn compl(&self) -> $T { -1 as $T ^ *self }
+}
 
 #[cfg(not(test))]
 impl BitOr<$T,$T> for $T {