on windows, functions of libbleu are not found

[hollyhook]

using microsoft visual compiler 14.0, fairseq 0.5.0
building libbleu dll by calling python setup.py build develop

functions in pyd are only exposed if they are declared as __declspec(dllexport).

problem is fixed if declaration of all exported C++ functions are changed, e.g.

extern "C" {
  __declspec(dllexport) void bleu_zero_init(bleu_stat* stat) {
    std::memset(stat, 0, sizeof(bleu_stat));
  }
}

[ShilinHe]

Have the same issue, can you share more details about the fix? where to put this code snippet?

[ShilinHe]

Let me elaborate more on the solution of @hollyhook. This issue is caused by the name changing problem during compiling. The compiler changed the function name, and thereby we cannot find the function.

To solve the problem, you should add __declspec(dllexport) before the function declaration. In this line (fairseq/fairseq/clib/libbleu/libbleu.cpp file), add the __declspec(dllexport) before function void bleu_zero_init, void bleu_one_init , and void bleu_add. Finally, call the python setup.py build develop, the problem would be fixed.

[huihuifan]

Thanks @ShilinHe ! @hollyhook , hope that resolves your issue. Please re-open if not.

[GeorgeS2019]

@myleott this modification needs to be included in the next release as part of pip install fairseq for Windows.

[erip]

I propose this should be re-opened. Requiring users to build your library from scratch is possible, but painful. I am not an expert at cross-compiling, but would it be as simple as conditionally adding the __declspec to the files in master? I don't know if that directive impacts Linux or OS X builds.