aplied suggestion to comment parameter name instead

dune/python/istl/preconditioners.hh

@@ -51,7 +51,7 @@ namespace Dune
     // -----------------------
 
     template< class X, class Y, class... options >
-    inline void registerPreconditioners ( pybind11::module module, pybind11::class_< LinearOperator< X, Y >, options...  > )
+    inline void registerPreconditioners ( pybind11::module module, pybind11::class_< LinearOperator< X, Y >, options...  > /*cls*/ )
     {
       typedef Dune::Preconditioner< X, Y > Preconditioner;