Cython not able to compile - windows

Question

I am trying to compile following trivial code with Cython on Windows7 (64bit) and WinPython:
File testpy.py:
print("hello world from testpy.py file.")
File compile.py
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
ext_modules = [
Extension("testpy", ["testpy.py"]),
# ... all your modules that need be compiled ...
]
setup(
name = 'My Program Name',
cmdclass = {'build_ext': build_ext},
ext_modules = ext_modules
)
I first give command to use mingw:
D:\myfolder> make_cython_use_mingw
cython has been set to use mingw32
to remove this, remove file "E:\WinPython\settings\pydistutils.cfg"
I then give command to compile:
D:\myfolder> python compile.py build_ext --inplace
The process starts but ends with following error:
running build_ext
skipping 'testpy.c' Cython extension (up-to-date)
building 'testpy' extension
C:\MinGW\bin\gcc.exe -mdll -O -Wall -IE:\WinPython\python-3.6.5.amd64\include -IE:\WinPython\python-3.6.5.amd64\include -c testpy.c -o build
\temp.win-amd64-3.6\Release\testpy.o
In file included from E:\WinPython\python-3.6.5.amd64\include/Python.h:68:0,
from testpy.c:4:
E:\WinPython\python-3.6.5.amd64\include/pytime.h:122:12: warning: 'struct timeval' declared inside parameter list will not be visible outsid
e of this definition or declaration
struct timeval *tv,
^~~~~~~
E:\WinPython\python-3.6.5.amd64\include/pytime.h:127:12: warning: 'struct timeval' declared inside parameter list will not be visible outsid
e of this definition or declaration
struct timeval *tv,
^~~~~~~
writing build\temp.win-amd64-3.6\Release\testpy.cp36-win_amd64.def
C:\MinGW\bin\gcc.exe -shared -s build\temp.win-amd64-3.6\Release\testpy.o build\temp.win-amd64-3.6\Release\testpy.cp36-win_amd64.def -LE:\Wi
nPython\python-3.6.5.amd64\libs -LE:\WinPython\python-3.6.5.amd64\PCbuild\amd64 -lpython36 -o D:\myfolder\testpy.cp36-win_amd64.pyd
Cannot export PyInit_testpy: symbol not defined
collect2.exe: error: ld returned 1 exit status
error: command 'C:\\MinGW\\bin\\gcc.exe' failed with exit status 1
Where is the problem and how can it be solved?
Edit:
On renaming py file as pyx as suggested by #ead in comments, it worked to create pyd file. However, on trying it gives following error:
D:\Myfolder>python -c "import Testpy"
Traceback (most recent call last):
File "<string>", line 1, in <module>
ImportError: DLL load failed: %1 is not a valid Win32 application.
Why is this not a valid Win32 application?
My python version is as follows:
Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 17:00:18) [MSC v.1900 64 bit (AMD64)] on win32
Edit: I found that I had mingw installed separately also (apart from part of winpython). I removed that and tried again. I am now getting following error:
python compile.py build_ext --inplace
Traceback (most recent call last):
File "compile.py", line 12, in <module>
ext_modules = ext_modules
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\core.py", line 148, in setup
dist.run_commands()
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\dist.py", line 955, in run_commands
self.run_command(cmd)
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\dist.py", line 974, in run_command
cmd_obj.run()
File "E:\WinPython\python-3.6.5.amd64\lib\site-packages\Cython\Distutils\old_build_ext.py", line 186, in run
_build_ext.build_ext.run(self)
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\command\build_ext.py", line 308, in run
force=self.force)
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\ccompiler.py", line 1031, in new_compiler
return klass(None, dry_run, force)
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\cygwinccompiler.py", line 282, in __init__
CygwinCCompiler.__init__ (self, verbose, dry_run, force)
File "E:\WinPython\python-3.6.5.amd64\lib\distutils\cygwinccompiler.py", line 126, in __init__
if self.ld_version >= "2.10.90":
TypeError: '>=' not supported between instances of 'NoneType' and 'str'
How can this be corrected?