EXPECT_EQ(TF_GraphNumFunctions(host_graph_), 1);
  EXPECT_EQ(TF_GraphGetFunctions(host_graph_, funcs, 0, s_), 0);
  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
  EXPECT_EQ(TF_GraphGetFunctions(host_graph_, funcs, 1, s_), 1);
  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
  AssertEqual(func0, funcs[0]);
  TF_DeleteFunction(funcs[0]);
  EXPECT_EQ(TF_GraphGetFunctions(host_graph_, funcs, 2, s_), 1);

  status->status = g->graph.AddGradientDef(std::move(gdef));
}

int TF_GraphNumFunctions(TF_Graph* g) {
  tensorflow::mutex_lock l(g->mu);
  return g->graph.flib_def().num_functions();
}

int TF_GraphGetFunctions(TF_Graph* g, TF_Function** funcs, int max_func,
                         TF_Status* status) {
  tensorflow::FunctionDefLibrary lib;
  {
    tensorflow::mutex_lock l(g->mu);
    lib = g->graph.flib_def().ToProto();

// all the returned TF_Functions. They must be deleted with TF_DeleteFunction.
// On error, returns 0, sets status to the encountered error, and the contents
// of funcs will be undefined.
TF_CAPI_EXPORT extern int TF_GraphGetFunctions(TF_Graph* g, TF_Function** funcs,
                                               int max_func, TF_Status* status);

// Note: The following function may fail on very large protos in the future.