problem in compiling C API in mingw

[m.overmeyer at yahoo.ca]

On Tuesday, 26 July 2011 23:53:36 UTC, llw... at gmail.com  wrote:
> Hi all again, 
>   I wonder if so far only Python 2.5.x support c extension. I try the
> MSVC 2010 and 2008, also try mingw (gcc 4.x.x) and swig. But even I try
> the simplest example, it said 
> 
> example_wrap.o:example_wrap.c:(.text+0x10ac): undefined reference to `_imp__PyObject_Free'
> example_wrap.o:example_wrap.c:(.text+0x10f5): undefined reference to `_imp__PyCapsule_Import'
> example_wrap.o:example_wrap.c:(.text+0x1100): undefined reference to `_imp__PyErr_Occurred'
> example_wrap.o:example_wrap.c:(.text+0x110e): undefined reference to `_imp__PyErr_Clear'
> example_wrap.o:example_wrap.c:(.text+0x1125): undefined reference to `_imp__PyImport_AddModule'
> example_wrap.o:example_wrap.c:(.text+0x1144): undefined reference to `_imp__PyCapsule_New'
> example_wrap.o:example_wrap.c:(.text+0x1165): undefined reference to `_imp__PyModule_AddObject'
> example_wrap.o:example_wrap.c:(.text+0x1170): undefined reference to `_imp__PyBaseObject_Type'
> example_wrap.o:example_wrap.c:(.text+0x11b2): undefined reference to `_imp__PyObject_SetAttr'
> example_wrap.o:example_wrap.c:(.rdata+0x1e8): undefined reference to `PyObject_GenericGetAttr'
> collect2: ld returned 1 exit status
> 
> and some sort like that.
> 
> So I try to use the compiler itself and get rid of all 3rd part tool,
> here is what I did
> 
> ///////////// source code
> #include "Python.h"
> 
> static  PyObject *
> ex_foo(PyObject *self, PyObject *args)
> {
>     printf("Hello, world n " );
>     Py_INCREF(Py_None);
>     return  Py_None;
> }
> 
> static  PyMethodDef example_methods[] = {
>     {"foo" , ex_foo, METH_VARARGS, "foo() doc string" },
>     {NULL , NULL }
> };
> 
> static  struct  PyModuleDef examplemodule = {
>     PyModuleDef_HEAD_INIT,
>     "example" ,
>     "example module doc string" ,
>     -1 ,
>     example_methods,
>     NULL ,
>     NULL ,
>     NULL ,
>     NULL
> };
> 
> PyMODINIT_FUNC
> PyInit_example(void )
> {
>     return  PyModule_Create(&examplemodule);
> }
> 
> /// my setup.py
> from distutils.core import setup, Extension
> 
> module1 = Extension('example', sources = ['example.c'])
> 
> setup (name = 'example', version = '1.0', description = 'This is a demo package', ext_modules = [module1])
> 
> 
> // running
> python setup.py build --compiler=mingw32
> 
> 
> $ python setup.py build --compiler=mingw32
> running build
> running build_ext
> building 'example' extension
> D:\Programs\MinGW\bin\gcc.exe -mno-cygwin -mdll -O -Wall "-Ic:\Program Files (x8
> 6)\Python\include" "-Ic:\Program Files (x86)\Python\PC" -c example.c -o build\te
> mp.win-amd64-3.1\Release\example.o
> writing build\temp.win-amd64-3.1\Release\example.def
> D:\Programs\MinGW\bin\gcc.exe -mno-cygwin -shared -s build\temp.win-amd64-3.1\Re
> lease\example.o build\temp.win-amd64-3.1\Release\example.def "-Lc:\Program Files
>  (x86)\Python\libs" "-Lc:\Program Files (x86)\Python\PCbuild\amd64" -lpython31 -
> lmsvcr90 -o build\lib.win-amd64-3.1\example.pyd
> build\temp.win-amd64-3.1\Release\example.o:example.c:(.text+0x13): undefined ref
> erence to `_imp___Py_NoneStruct'
> build\temp.win-amd64-3.1\Release\example.o:example.c:(.text+0x32): undefined ref
> erence to `_imp__PyModule_Create2'
> collect2: ld returned 1 exit status
> error: command 'gcc' failed with exit status 1
> --------------------- Original Message Ends --------------------

You are linking against the static version of the Python library. If you link against the DLL version, this problem goes away.

-Lc:\Program Files(x86)\Python\libs" should just be "-Lc:\Program Files(x86)\Python\", assuming that's where the Python DLLs are.

See:
https://stackoverflow.com/questions/5159353/how-can-i-get-rid-of-the-imp-prefix-in-the-linker-in-vc#5159395