func.func @check_sharding_attrs_exists_for_empty_cluster_func() {
  "tf_device.cluster_func"() {func = @empty_func, step_marker_location = "", num_cores_per_replica = 1 : i64} : () -> ()
  // CHECK: input_sharding_configuration = []
  // CHECK: output_sharding_configuration = []
  func.return
}

// CHECK-LABEL: func @empty_func() {
func.func @empty_func() {
  func.return
}

// -----

    func @tf_tpu_rewrite(%arg0: tensor<8xi32>) -> tensor<8xi32> {
      %0 = "tf_device.cluster_func"(%arg0) {_xla_compile_device_type = "TPU", _replication_info = "cluster0", func = @func, num_cores_per_replica = 2, input_sharding_configuration = ["\08\01\1A\01\01\22\01\00"], output_sharding_configuration = ["\08\01\1A\01\01\22\01\00"]} : (tensor<8xi32>) -> tensor<8xi32>
      return %0 : tensor<8xi32>
    }
    ```

    will be rewritten as:

%3, %5, %6) {_xla_compile_device_type = "TPU", _replication_info = "while/cluster_while_body_271", allow_soft_placement = false, computation_shape = [], device = "", device_assignment = [0, 0, 0, 0], func = @_func, host_compute_core = [], input_sharding_configuration = ["\08\01\1A\01\01\22\01\00", "\08\01\1A\01\01\22\01\00", "\08\01\1A\01\01\22\01\00", "\08\01\1A\01\01\22\01\00"], num_cores_per_replica = 1 : i64, output_sharding_configuration = ["\08\01\1A\01\01\22\01\00", "\08\01\1A\01\01\22\01\00"],...

    attributes, and `func` receives the mhlo.sharding attribute:

    ```mlir
      func @test(%arg0: tensor<*xi32>) {
        %0 = "tf_device.cluster_func"(%arg0) {
            func = @func,
            input_sharding_configuration = ["\01\02\03"],
            output_sharding_configuration = ["\08\01\1A\01\01\22\01\00"],
            step_marker_location = ""} : (tensor<*xi32>) -> tensor<*xi32>
        return
      }