MXNet model export to ONNX failed

[xizi]

export rnn.GRU op failed, error message as follow:
AttributeError: No conversion function registered for op type _rnn_param_concat yet.

[szha]

Thanks for reporting. We are removing that op in the RNN layer in the 2.0. It will need to be registered in 1.x. That operator should be registered as simple concatenation for ONNX.

[xizi]

Thanks for reply. Can your provide some references show how to register _rnn_param_concat op as concatenation.

[szha]

for export, I think it would be something similar to this:
https://github.com/apache/incubator-mxnet/blob/85ff00d5c1dafc1e51aaae26f6664582b0eb6ae1/python/mxnet/contrib/onnx/mx2onnx/_op_translations.py#L846-L861

[xizi]

After installed mxnet2.0 build from source. export model error:
NotImplementedError: Only LSTM mode RNN conversion to ONNX is currently supported.

[szha]

cc @josephevans
conversion of other RNN types will need to be added.