When the '--swig-opts -c++' command line option is
used, the target extension is changed from .c to .cpp
but when the '-c++' option is passed to an Extension
with the swig_opts keyword argument, the target
extension is not changed. This causes the compiler to
treat the C++ source as C and fail.

With the patch distutils uses the Extension's swig_opts
argument in addition to the command line options to
determine if the target extension should be .c or .cpp.

Here are examples of what arguments get used with the
executables in different situations:

Without -c++
swig.exe -python -Iinclude -o
interface/interface_wrap.c interface/interface.i
cl.exe /c /nologo /Ox /MD /W3 /GX /DNDEBUG -Iinclude
-IC:\Python24\include -IC:\Python24\PC
/Tcinterface/interface_wrap.c
/Fobuild\temp.win32-2.4\Release\interface/interface_wrap.obj

With -c++ (as command line option)
swig.exe -python -Iinclude -c++ -o
interface/interface_wrap.cpp interface/interface.i
cl.exe /c /nologo /Ox /MD /W3 /GX /DNDEBUG -Iinclude
-IC:\Python24\include -IC:\Python24\PC
/Tpinterface/interface_wrap.cpp
/Fobuild\temp.win32-2.4\Release\interface/interface_wrap.obj

With -c++ (in swig_opts in setup.py)
swig.exe -python -Iinclude -c++ -o
interface/interface_wrap.c interface/interface.i
cl.exe /c /nologo /Ox /MD /W3 /GX /DNDEBUG -Iinclude
-IC:\Python24\include -IC:\Python24\PC
/Tcinterface/interface_wrap.c
/Fobuild\temp.win32-2.4\Release\interface/interface_wrap.obj

With -c++ (in swig_opts in setup.py with patch applied)
swig.exe -python -Iinclude -c++ -o
interface/interface_wrap.cpp interface/interface.i
cl.exe /c /nologo /Ox /MD /W3 /GX /DNDEBUG -Iinclude
-IC:\Python24\include -IC:\Python24\PC
/Tpinterface/interface_wrap.cpp
/Fobuild\temp.win32-2.4\Release\interface/interface_wrap.obj

Problem still exists as of 23/03/07 in Python 2.5, patch appears to be correct solution.

This works in my current version of distutils (Python 2.5.2, from Ubuntu
Intrepid). Maybe it was fixed and no-one noticed that this bug was
relevant ;)

Is this still a problem?

We need to add a test for this behavior, to make sure it is fixed and to prevent regressions.

Distutils is now deprecated (see PEP 632) and all tagged issues are being closed. From now until removal, only release blocking issues will be considered for distutils.

If this issue does not relate to distutils, please remove the component and reopen it. If you believe it still requires a fix, most likely the issue should be re-reported at https://github.com/pypa/setuptools