Re: [Swig-user] Swig/C++ unresolved python externals such as __Py_NotImplementedStruct

[Bob H. <bh...@co...>]

On 10/27/2014 4:19 PM, Paul Silvis wrote:
> I'm trying to wrap an existing dll that references other dlls.  I'm using
> Visual Studio 2013 and Python27 (32 bit).  When I get to the linker it
> complains about unresolved externals:
>
> __Py_NotImplementedStruct
> _PyBool_Type
> _PyFloat_Type
> _PyClass_Type
>
> ... and so on.  I know that other Python symbols _are_ being found
> (Python27\libs\python27.lib is a linker input, and the /verbose mode shows
> me all sorts of symbols being found there), but don't understand where these
> should come from. 
>
> Any ideas?

"PyBool_Type" is a data type defined in the Python source code,
Objects/boolobject.c (line 150 in Python 2.7.7):

   PyTypeObject PyBool_Type = {...

The definition of "Py_NotImplementedStruct" can be found in Objects/object.c
(again, Python 2.7.7):

  PyObject _Py_NotImplementedStruct = {...

At a guess, [a] you're project is not linking to the correct Python static
library (e.g., python27.lib under Windows), [b] those symbols in the library
are not publicly visible, or [c] those symbols aren't actually in your library
(for some reason).

You might use a utility to dump the strings in the "python27.lib" file to see
if those symbols appear.  For example:

   $ strings python27.lib | grep PyBool_Type
   __imp_PyBool_Type
   __imp_PyBool_Type
   PyBool_Type

   $ strings python27.lib | grep Py_NotImplementedStruct
   __imp__Py_NotImplementedStruct
   __imp__Py_NotImplementedStruct
   _Py_NotImplementedStruct