Fix pretty-printing of empty impl items

src/libsyntax/print/pprust.rs

@@ -586,11 +586,13 @@ pub fn print_item(s: @ps, item: &ast::item) {
         };
 
         print_type(s, ty);
-        space(s.s);
 
         if methods.len() == 0 {
             word(s.s, ";");
+            end(s); // end the head-ibox
+            end(s); // end the outer cbox
         } else {
+            space(s.s);
             bopen(s);
             for meth in methods.iter() {
                print_method(s, *meth);

src/test/pretty/empty-impl.pp

@@ -0,0 +1,5 @@
+trait X { }
+impl X for T;
+
+trait Y { }
+impl Y for T;

src/test/pretty/empty-impl.rs

@@ -0,0 +1,5 @@
+trait X { }
+impl X for T;
+
+trait Y { }
+impl Y for T;