Cannot build using Mingw

[joda01]

Bug Report

Describe the bug

It is not possible to build onnx lib using Mingw because windows.h defines a macro named OPTIONAL which is used as variable name in the onnx lib. This leads to a compiler error.

System information

• Windows Server 2022
• ONNX 1.72, 1.16.2
• mingw 13.2
• CMake 3.30.5

Reproduction instructions

Try to build onnx static lib using cmake and windows

Expected behavior

Build ONNX library successfully.

Notes

Relates to #1065
Relates to conan-io/conan-center-index#25468

Logs

Click to expand log

onnx/1.16.2: Running CMake.build()
...
[ 35%] Building CXX object CMakeFiles/onnx.dir/onnx/defs/controlflow/defs.cc.obj
In file included from /src/onnx/onnx-data_pb.h:9,
                 from /src/onnx/checker.h:15,
                 from /src/onnx/common/path.h:20,
                 from src\onnx\common\path.cc:7:
/build/Release/onnx/onnx-data.pb.h:259:38: error: expected unqualified-id before '=' token
  259 |   static constexpr DataType OPTIONAL =
      |                                      ^
/build/Release/onnx/onnx-data.pb.h:827:38: error: expected unqualified-id before '=' token
  827 |   static constexpr DataType OPTIONAL =
      |                                      ^
mingw32-make[2]: *** [CMakeFiles\onnx.dir\build.make:151: CMakeFiles/onnx.dir/onnx/common/path.cc.obj] Error 1
mingw32-make[2]: *** Waiting for unfinished jobs....
mingw32-make[1]: *** [CMakeFiles\Makefile2:193: CMakeFiles/onnx.dir/all] Error 2
mingw32-make: *** [Makefile:135: all] Error 2

onnx/1.16.2: ERROR:

[andife]

Many thanks for the find.

@justinchuby I wonder if an additional test can be added to the CI pipeline to test whether building with mingw works. It could only run once a week, for example.

[justinchuby]

Many thanks for the find.

@justinchuby I wonder if an additional test can be added to the CI pipeline to test whether building with mingw works. It could only run once a week, for example.

We may do that if anyone wants to contribute? Though I’m not sure how much effort is required to maintain it