message: fixes residual_norm precision dispatch for non-mpi
diff: @@ -94,6 +94,7 @@ bool any_is_complex(const LinOp* in, Rest&&... rest)
  template <typename ValueType, typename Function, typename... LinOps>
  void norm_dispatch(Function&& fn, LinOps*... linops)
  {
  +#if GINKGO_BUILD_MPI
  if (gko::detail::is_distributed(linops...)) {
  if (any_is_complex<ValueType>(linops...)) {
  distributed::precision_dispatch<to_complex<ValueType>>(
  @@ -102,7 +103,9 @@ void norm_dispatch(Function&& fn, LinOps*... linops)
  distributed::precision_dispatch<ValueType>(
  std::forward<Function>(fn), linops...);
  }
  - } else {
  + } else
  +#endif
  + {
  if (any_is_complex<ValueType>(linops...)) {
  precision_dispatch<to_complex<ValueType>>(
  std::forward<Function>(fn), linops...);
  