message: try adding the lambda
diff: @@ -112,8 +112,14 @@ void compute_coarse_coo(std::shared_ptr<const DefaultExecutor> exec,
  auto coarse_key_it = oneapi::dpl::make_zip_iterator(
  coarse_coo->get_row_idxs(), coarse_coo->get_col_idxs());
  - oneapi::dpl::reduce_by_segment(policy, key_it, key_it + fine_nnz, vals,
  - coarse_key_it, coarse_coo->get_values());
  + oneapi::dpl::reduce_by_segment(
  + policy, key_it, key_it + fine_nnz, vals, coarse_key_it,
  + coarse_coo->get_values(),
  + [](auto a, auto b) {
  + return std::tie(std::get<0>(a), std::get<1>(a)) ==
  + std::tie(std::get<0>(b), std::get<1>(b));
  + },
  + [](auto a, auto b) { return a + b; });
  }
  GKO_INSTANTIATE_FOR_EACH_VALUE_AND_INDEX_TYPE(
  