Linking errors when compiling python extension module

Question

So I'm writing a python extension module in C and I'm trying to compile it for my 64-bit Python build. After bashing my head against MinGW for a while, I did some googling around and found that MinGW doesn't do 64-bit extension modules, so I set up Visual C++ 2008 Express with the Win7 SDK and DISTUTILS_USE_SDK and MSSdk both equal to 1 as in the answers to this question.

I finally got Distutils to find the compilers, but when I compile the extension I get this output:

core.obj : error LNK2019: unresolved external symbol __imp__PyErr_NoMemory refer
enced in function "int __cdecl handleErrors(int)" (?handleErrors@@YAHH@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyErr_SetString refe
renced in function "int __cdecl handleErrors(int)" (?handleErrors@@YAHH@Z)
core.obj : error LNK2019: unresolved external symbol _opus_encoder_destroy refer
enced in function "void __cdecl OpusEncoder_dealloc(struct OpusEncoderObject *)"
 (?OpusEncoder_dealloc@@YAXPAUOpusEncoderObject@@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__Py_BuildValue refere
nced in function "int __cdecl OpusEncoder_init(struct OpusEncoderObject *,struct
 _object *,struct _object *)" (?OpusEncoder_init@@YAHPAUOpusEncoderObject@@PAU_o
bject@@1@Z)
core.obj : error LNK2019: unresolved external symbol _opus_encoder_create refere
nced in function "int __cdecl OpusEncoder_init(struct OpusEncoderObject *,struct
 _object *,struct _object *)" (?OpusEncoder_init@@YAHPAUOpusEncoderObject@@PAU_o
bject@@1@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyArg_ParseTupleAndK
eywords referenced in function "int __cdecl OpusEncoder_init(struct OpusEncoderO
bject *,struct _object *,struct _object *)" (?OpusEncoder_init@@YAHPAUOpusEncode
rObject@@PAU_object@@1@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyTuple_Pack referen
ced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncoderO
bject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderObj
ect@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyString_FromString
referenced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusE
ncoderObject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEnc
oderObject@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol _opus_encode_float referenc
ed in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncoderOb
ject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderObje
ct@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyFloat_AsDouble ref
erenced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEnco
derObject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncode
rObject@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyType_IsSubtype ref
erenced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEnco
derObject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncode
rObject@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyFloat_Type referen
ced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncoderO
bject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderObj
ect@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol _opus_encode referenced in
function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncoderObject *
,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderObject@@PA
U1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyErr_Occurred refer
enced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncode
rObject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderO
bject@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyInt_AsLong referen
ced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEncoderO
bject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncoderObj
ect@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyArg_ParseTuple ref
erenced in function "struct _object * __cdecl OpusEncoder_encode(struct OpusEnco
derObject *,struct _object *)" (?OpusEncoder_encode@@YAPAU_object@@PAUOpusEncode
rObject@@PAU1@@Z)
core.obj : error LNK2019: unresolved external symbol __imp__PyModule_AddObject r
eferenced in function _initopys
core.obj : error LNK2019: unresolved external symbol __imp__PyErr_NewException r
eferenced in function _initopys
core.obj : error LNK2019: unresolved external symbol __imp__Py_InitModule4 refer
enced in function _initopys
core.obj : error LNK2019: unresolved external symbol __imp__PyType_Ready referen
ced in function _initopys
core.obj : error LNK2019: unresolved external symbol __imp__PyType_GenericNew re
ferenced in function _initopys
core.obj : error LNK2019: unresolved external symbol __imp__Py_Initialize refere
nced in function _main
core.obj : error LNK2019: unresolved external symbol __imp__Py_SetProgramName re
ferenced in function _main
build\lib.win-amd64-2.7\opys.pyd : fatal error LNK1120: 23 unresolved externals
error: command '"C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\link.
exe"' failed with exit status 1120

I've kinda hit a wall here after banging my head against this for 3 days, any advice?

Answer 1

In my experience, it's very difficult to build python modules on windows with anything from Microsoft except the full version of Visual C++. Further, the version of Visual Studio must match the version that was used to build your python distribution.

For example, with the official binary dist of Python 2.7.1:

C:\Python27>python
Python 2.7.1 (r271:86832, Nov 27 2010, 18:30:46) [MSC v.1500 32 bit (Intel)] on win32
...

According to What version of Visual Studio is Python on my computer compiled with?, that means that python was built with Visual C++ 2008.

For each version of Visual Studio, there is a corresponding version of the Windows SDK, so if you want to try to make this work with free tools, you need to find and install the correct Windows SDK version. I think that might be http://www.microsoft.com/en-us/download/details.aspx?id=24826, but I'm not 100% sure.

Answer 2

I had the same error. Installing psycopg2 from https://github.com/nwcell/psycopg2-windows solved my problem

Answer 3

For my case , changing project properties in Visual studio (building solution for x64 instead of x86) helped , as Python version I was using was 64 bit . Both the versions shall match.

Answer 4

1、you must make sure that python x64、oracle client x64（win7 x64），all the versions must match.

2、perhaps you have to "install vc++ for python2.7"