func.func @unknown_rank_arg(%arg: tensor<*xi8>) -> tensor<*xi8> {
      return %arg : tensor<*xi8>
    }
  )mlir";

  OwningOpRef<ModuleOp> module_op =
      ParseModuleOpString(kArgumentWithUnknownRank);
  ASSERT_TRUE(module_op);

  auto func_op = module_op->lookupSymbol<func::FuncOp>("unknown_rank_arg");
  ASSERT_THAT(func_op, NotNull());