signature->add_output_arg();
  }
  return func;
}

// A SavedConcreteFunction whose canonicalized input signature
// has less inputs than its corresponding FunctionDef should cause an error.
TEST_F(SavedConcreteFunctionLoadingTest, TooFewInputsInSavedConcreteFunction) {
  // `saved` has 1 input
  SavedConcreteFunction saved;
  *saved.mutable_canonicalized_input_signature() =
      testing::SingleArgInputSignature();

  // TensorHandle captures for this funtion
  std::vector<ImmediateExecutionTensorHandle*> captures;

  // SavedConcreteFunction contains much of the metadata of the expected "types"
  // of the inputs and outputs of a function.
  // Note(bmzhao): saved_concrete_func_ is guaranteed to be non-null.
  const SavedConcreteFunction* saved_concrete_func;

  // This field is only present on TF2 ConcreteFunctions, and is useful for

                      absl::Span<const AssetFileDef> assets,
                      std::unique_ptr<Asset>* output);

// Creates a TFConcreteFunction from a SavedConcreteFunction.
Status LoadTFConcreteFunction(
    const SavedConcreteFunction& saved_concrete_function,
    const FunctionDef* function_def,
    const std::unordered_map<int, std::unique_ptr<TensorHandleConvertible>>&
        captured_objects,

      return absl::FailedPreconditionError(
          absl::StrCat("Resource at node ", node_id,
                       " did not have a create_resource() function"));
    }
    const SavedConcreteFunction* saved_create_resource_fn =
        create_resource_fn->saved_concrete_func;
    if (!saved_create_resource_fn->bound_inputs().empty()) {
      // TODO(b/124045874): Support loading resource functions via a top sort

  // non-null.
  const FunctionDef* fdef = nullptr;

  // SavedConcreteFunction contains much of the metadata of the expected "types"
  // of the inputs and outputs of a function.
  // Note(bmzhao): saved_concrete_func_ is guaranteed to be non-null.
  const SavedConcreteFunction* saved_concrete_func = nullptr;

  // The name of the SignatureDef key.
  std::string signature_key;

// output signatures with respect to the corresponding FunctionDef's input
// and output args.
Status ValidateSavedFunctionCompatibleWithFunctionDef(
    const SavedConcreteFunction& saved_concrete_function,
    const FunctionDef* function_def) {
  // tf.functions go through many transformations before becoming FunctionDefs
  // 1. flatten user-provided inputs:

namespace runtime {

using tensorflow::AbstractContext;
using tensorflow::AbstractFunctionPtr;
using tensorflow::DataType;
using tensorflow::FunctionDef;
using tensorflow::PartialTensorShape;
using tensorflow::SavedConcreteFunction;
using tensorflow::SavedObjectGraph;
using tensorflow::Status;
using tensorflow::StructuredValue;
using tensorflow::TensorSpecProto;
using tensorflow::libexport::TFPackage;

absl::StatusOr<uint64_t> RegularizeAndHashSavedObjectGraph(
    const SavedObjectGraph& object_graph_def) {
  // Sort `concrete_functions`, which is an unordered map from function names to
  // SavedConcreteFunction, using the suffix UID of the function name. Assumes
  // that the trackable children are listed in a deterministic order during
  // serialization.
  absl::btree_map<int64_t, std::string> uid_to_function_names;

      // We only allow a single input signature to each SavedFunction.
      // This assumption means we have a 1:1 correspondence between
      // tf.function <=> SavedFunction <=> SavedConcreteFunction <=> FunctionDef
      // This makes defining the ABI easier (or even well-defined at all).
      // TODO(silvasean): How to detect a function that doesn't have an