[Distutils] why not link modules against msvcrt.dll istead of versioned msvcr*.dll? (mingw32)

[Ralf Schmitt]

Václav Šmilauer <eu at doxos.eu> writes:

> Hi everybody,
>
> I recently (inconclusively) discussed on the mingw-w64 mailing list
> why are compiled modules linked to msvcrt90 (depending on python
> build) rather than to msvcrt. A compiled module was crashing (the DLL
> would not load with "invalid access to memory and such") with msvcr90,
> while it works just fine with msvcrt.

I've also had problems with that with mingw-w64. The programs using
mingw-w64 compiled extensions did crash randomly.

I've replaced get_msvcr() in distutils/cygwinccompiler.py to just return
an empty list:

 def get_msvcr():
     """Include the appropriate MSVC runtime library if Python was built
     with MSVC 7.0 or later.
     """
+    return []

>
> My understanding (based on
> http://msdn.microsoft.com/en-us/library/abx4dbyh.aspx,
> http://msdn.microsoft.com/en-us/library/ms235460.aspx and my
> aforementioned experience)  is that loading two MSVC runtimes at the
> same time is asking for trouble. Dependency Walker shows me that
> python27.dll itself is linking against msvcrt.dll, but
> distutils.cygwincompiler will link against msvcrt90 nevertheless. This
> means both end up loaded.
>
> OTOH I suppose there is a good reason why msvc version detection
> exists, but I am just ignorant of it and would like to ask here.

My guess would be that it's needed for some older gcc version. It looks
like none of the python developers care enough to fix issues with
mingw-w64.

-- 
Cheers
Ralf