错误 LNK2001：无法解析的外部符号 PyInit_

Question

我正尝试按照本教程在 python 中使用 C 代码。 http://dfm.io/posts/python-c-extensions/

这是要点https://gist.github.com/GreenJoey/b08528d6abe62da70f28f73c39c0efd0

当我尝试使用 python setup.py build_ext --inplace 编译它时，它失败并显示此错误消息：

running build_ext
No module named 'numpy.distutils._msvccompiler' in numpy.distutils; trying from distutils
building '_chi2' extension
creating build\temp.win-amd64-3.6
creating build\temp.win-amd64-3.6\Release
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\x86_amd64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\lib\site-packages\numpy\core\include -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\include -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\include -I"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE" -I"C:\Program Files (x86)\Windows Kits\include.0.10240.0\ucrt" -I"C:\Program Files (x86)\Windows Kits.1\include\shared" -I"C:\Program Files (x86)\Windows Kits.1\include\um" -I"C:\Program Files (x86)\Windows Kits.1\include\winrt" /Tc_chi2.c /Fobuild\temp.win-amd64-3.6\Release\_chi2.obj
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\x86_amd64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\lib\site-packages\numpy\core\include -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\include -IC:\Users\XXX\AppData\Local\Continuum\anaconda3\include -I"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE" -I"C:\Program Files (x86)\Windows Kits\include.0.10240.0\ucrt" -I"C:\Program Files (x86)\Windows Kits.1\include\shared" -I"C:\Program Files (x86)\Windows Kits.1\include\um" -I"C:\Program Files (x86)\Windows Kits.1\include\winrt" /Tcchi2.c /Fobuild\temp.win-amd64-3.6\Release\chi2.obj
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\x86_amd64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED,ID=2 /MANIFESTUAC:NO /LIBPATH:C:\Users\XXX\AppData\Local\Continuum\anaconda3\libs /LIBPATH:C:\Users\XXX\AppData\Local\Continuum\anaconda3\PCbuild\amd64 /LIBPATH:"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\LIB\amd64" /LIBPATH:"C:\Program Files (x86)\Windows Kits\lib.0.10240.0\ucrt\x64" /LIBPATH:"C:\Program Files (x86)\Windows Kits.1\lib\winv6.3\um\x64" /EXPORT:PyInit__chi2 build\temp.win-amd64-3.6\Release\_chi2.obj build\temp.win-amd64-3.6\Release\chi2.obj /OUT:C:\workspace\c\b08528d6abe62da70f28f73c39c0efd0-a1d1f0469637e3a3578ab5f8ee0e641a8e31d572\_chi2.cp36-win_amd64.pyd /IMPLIB:build\temp.win-amd64-3.6\Release\_chi2.cp36-win_amd64.lib
LINK : error LNK2001: unresolved external symbol PyInit__chi2
build\temp.win-amd64-3.6\Release\_chi2.cp36-win_amd64.lib : fatal error LNK1120: 1 unresolved externals
error: Command "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\BIN\x86_amd64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED,ID=2 /MANIFESTUAC:NO /LIBPATH:C:\Users\XXX\AppData\Local\Continuum\anaconda3\libs /LIBPATH:C:\Users\XXX\AppData\Local\Continuum\anaconda3\PCbuild\amd64 /LIBPATH:"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\LIB\amd64" /LIBPATH:"C:\Program Files (x86)\Windows Kits\lib.0.10240.0\ucrt\x64" /LIBPATH:"C:\Program Files (x86)\Windows Kits.1\lib\winv6.3\um\x64" /EXPORT:PyInit__chi2 build\temp.win-amd64-3.6\Release\_chi2.obj build\temp.win-amd64-3.6\Release\chi2.obj /OUT:C:\workspace\c\b08528d6abe62da70f28f73c39c0efd0-a1d1f0469637e3a3578ab5f8ee0e641a8e31d572\_chi2.cp36-win_amd64.pyd /IMPLIB:build\temp.win-amd64-3.6\Release\_chi2.cp36-win_amd64.lib" failed with exit status 1120

看起来找不到unresolved external symbol PyInit__chi2但是方法已经定义了。参见 https://gist.github.com/GreenJoey/b08528d6abe62da70f28f73c39c0efd0#file-_chi2-c-L33

我知道这是一个链接错误，但是我只导入了一次"Python.h"所以我不明白为什么它找不到方法。

Answer 1

我在这里找到了灵魂https://gist.github.com/douglas-larocca/099bf7460d853abb7c17

PyInit 必须标记为 PyMODINIT_FUNC

PyMODINIT_FUNC PyInit__chi2(void)
{

    PyObject *module;
    static struct PyModuleDef moduledef = {
        PyModuleDef_HEAD_INIT,
        "_chi2",
        module_docstring,
        -1,
        module_methods,
        NULL,
        NULL,
        NULL,
        NULL
    };
    module = PyModule_Create(&moduledef);
    if (!module) return NULL;

    /* Load `numpy` functionality. */
    import_array();

    return module;
}

Answer 2

在我的例子中，这个错误是由于我在 setup.py 中提供的模块名称与我的 cpp 绑定文件中的 PYBIND11_MODULE() 宏中使用的模块名称不匹配所致（宏的第一个参数）。

错误 LNK2001：无法解析的外部符号 PyInit_

error LNK2001: unresolved external symbol PyInit_

c

python

cpython