Known macOS build issues with Protobuf version 3.19 and 3.20

[hamptonm1]

When upgrading protobuf from 3.18.3 to 3.20.3, I noticed the macOS build failed with the following:

Undefined symbols for architecture x86_64:
[720](https://github.com/onnx/onnx-mlir/actions/runs/3743651637/jobs/6356066681#step:10:721)
  "google::protobuf::internal::InternalMetadata::~InternalMetadata()", referenced from:
[721](https://github.com/onnx/onnx-mlir/actions/runs/3743651637/jobs/6356066681#step:10:722)
      google::protobuf::MessageLite::~MessageLite() in libonnx_proto.a(onnx-ml.pb.cc.o)
[722](https://github.com/onnx/onnx-mlir/actions/runs/3743651637/jobs/6356066681#step:10:723)
      google::protobuf::MessageLite::~MessageLite() in libonnx_proto.a(onnx-data.pb.cc.o)
[723](https://github.com/onnx/onnx-mlir/actions/runs/3743651637/jobs/6356066681#step:10:724)
ld: symbol(s) not found for architecture x86_64

This is actually a known issue in the protobuf community, please see the following issues:
protocolbuffers/protobuf#9947
facebookincubator/velox#2029

This problem is fixed in protobuf version 3.21.3, however onnx community has not upgraded to that version. Instead they are on version 3.20.3 which is where the failure lies. There is a workaround if we still want to upgrade to version 3.20.3 by adding the following to the CMake.txt file:

add_definitions(-DNDEBUG)

[hamptonm1]

Should we upgrade to protobuf 3.20.3 and include the workaround or should we wait for onnx to upgrade to 3.21.3 which fixes the issue and therefore we do not need the workaround. @AlexandreEichenberger @gongsu832 @chentong319 @tungld ? Any comments about this topic :)

[gongsu832]

In general, only upgrade when there is a specific reason to do so. Stay in sync with onnx is desirable but if the new version has known problem like the one above, I'd wait until things get sorted out.

[chentong319]

To my understanding, protobuf 3.20.3 is required by onnx opset 18. protobuf 3.21 is needed for Mac to fix the issue with protobuf 3.20.3 on Mac. Can protobuf 3.21.3 work with other components in onnx-mlir? Open a draft PR to try?

[hamptonm1]

To my understanding, protobuf 3.20.3 is required by onnx opset 18. protobuf 3.21 is needed for Mac to fix the issue with protobuf 3.20.3 on Mac. Can protobuf 3.21.3 work with other components in onnx-mlir? Open a draft PR to try?

So the onnx community upgraded to 3.20.2 because 3.18.3 is out of maintenance window as shown in the following PR : onnx/onnx#4629. So it is not required to use opset 18 from what I read. I can create a draft PR and test what happens while using protobuf 3.21. Then everyone can decide based on my results.

[chentong319]

Thanks for your efforts. Your draft PR ran through on Mac, AMD and PPC Linux, but failed on S390 and Windows. It seems that Protobuf 3.20.2 is not available for Windows and can not be built on S390.

[hamptonm1]

Thanks for your efforts. Your draft PR ran through on Mac, AMD and PPC Linux, but failed on S390 and Windows. It seems that Protobuf 3.20.2 is not available for Windows and can not be built on S390.

@chentong319 Yes I tested Protobuf 3.20.2, 3.20.3 and 3.21.3 which failed for some checks and not for others. So I guess we will have to remain at the version we are currently on.

[chentong319]

Yes, remain at the version we are currently on. Is it possible to use a different version for Mac only? Even if the git build for Mac fails for a while due to the Protobuf 3.18, I am building onnx-mlir locally on my Mac using Protobuf 3.20.3.

[hamptonm1]

Yes, remain at the version we are currently on. Is it possible to use a different version for Mac only? Even if the git build for Mac fails for a while due to the Protobuf 3.18, I am building onnx-mlir locally on my Mac using Protobuf 3.20.3.

Interesting!! Okay let me try that.