Address review

src/libcore/convert.rs

@@ -276,7 +276,7 @@ pub trait Into<T>: Sized {
 pub trait From<T>: Sized {
     /// Performs the conversion.
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn from(t: T) -> Self;
+    fn from(_: T) -> Self;
 }
 
 /// An attempted conversion that consumes `self`, which may or may not be

src/librustdoc/html/highlight.rs

@@ -134,7 +134,7 @@ pub trait Writer {
     fn string<T: Display>(&mut self,
                           text: T,
                           klass: Class,
-                          tas: Option<&TokenAndSpan>)
+                          tok: Option<&TokenAndSpan>)
                           -> io::Result<()>;
 }