NotSupportedError error when executing Readme example "TorchScript ResNet18"

[trirpi]

When executing the TorchScript ResNet18 example in the Readme, I get a NotSupportedError.

To replicate, execute:

python projects/pt1/examples/torchscript_resnet18.py

This is part of the stacktrace:

  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/_functorch/_aot_autograd/jit_compile_runtime_wrappers.py", line 434, in aot_dispatch_autograd
    compiled_fw_func = aot_config.fw_compiler(fw_module, adjusted_flat_args)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch_mlir/dynamo.py", line 139, in wrapper_backend
    user_callable = user_backend(gm, example_inputs)
  File "/home/trirpi/torch-mlir/projects/pt1/examples/torchdynamo_resnet18.py", line 78, in refbackend_torchdynamo_backend
    mlir_module = torchscript.compile(
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch_mlir/torchscript.py", line 350, in compile
    scripted = torch.jit.script(model)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_script.py", line 1341, in script
    return torch.jit._recursive.create_script_module(
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_recursive.py", line 558, in create_script_module
    return create_script_module_impl(nn_module, concrete_type, stubs_fn)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_recursive.py", line 571, in create_script_module_impl
    method_stubs = stubs_fn(nn_module)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_recursive.py", line 894, in infer_methods_to_compile
    stubs.append(make_stub_from_method(nn_module, method))
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_recursive.py", line 87, in make_stub_from_method
    return make_stub(func, method_name)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/_recursive.py", line 71, in make_stub
    ast = get_jit_def(func, name, self_name="RecursiveScriptModule")
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/frontend.py", line 372, in get_jit_def
    return build_def(
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/frontend.py", line 422, in build_def
    param_list = build_param_list(ctx, py_def.args, self_name, pdt_arg_types)
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/jit/frontend.py", line 448, in build_param_list
    raise NotSupportedError(ctx_range, _vararg_kwarg_err)
torch._dynamo.exc.BackendCompilerFailed: backend='compiler_fn' raised:
NotSupportedError: Compiled functions can't take variable number of arguments or use keyword-only arguments with defaults:
  File "/home/trirpi/venv/lib/python3.10/site-packages/torch/fx/_lazy_graph_module.py", line 112
    def _lazy_forward(self, *args, **kwargs):
                                    ~~~~~~~ <--- HERE

As mentioned in Issue #3204, this uses unowned code (make_simple_dynamo_backend). However, this example is displayed very prominently in the Readme, so I think it should be fixed or removed from the readme.