[Python-Dev] [C++-sig] GCC version compatibility (original) (raw)

Christoph Ludwig cludwig at cdc.informatik.tu-darmstadt.de
Sun Jul 10 16:49:47 CEST 2005

On Sun, Jul 10, 2005 at 09:35:33AM -0400, David Abrahams wrote:

Christoph Ludwig <cludwig at cdc.informatik.tu-darmstadt.de> writes:

> I do not claim the 2 TUs test will cover all possible scenarios. I am not even > sure this decision should be left to an automated test. Because if the test > breaks for some reason then the user is left with a linker error that is > time-consuming to track down. However, at least by the usual hierarchy of values, the sort of runtime error that results from the current needless linking with C++ on ELF/Linux is even worse.

Yes, but on ELF/Linux the default configuration should be --without-cxx in the first place. If the build instructions make it sufficiently clear that you should prefer this configuration whenever possible then this should be a non-issue on platforms like ELF/Linux.

We learned that there are indeed platforms that require --with-cxx. There is not much we can do for user on platforms that that also require the final executable to be linked with the C++ compiler. They have to live with the dependency on the C++ runtime and the likely runtime errors if the import extension modules built with a different C++ compiler.

What about the platforms that require compilation of main() with a C++ compiler but allow you to link with the C compiler - can you import a C++ extension module built with C++ compiler version X if the main() function of the Python interpreter was compiled with C++ compiler version Y, X != Y? If not, then we are back to the runtime error, no matter whether there is a dependency on the C++ runtime library or not.

So the automated test in configure could spare users runtime errors if they must configure --with-cxx and if they can link with the C compiler and if the C++ compiler versions used for building the Python interpreter and the extension module do not need to coincide. I don't know how large the subset of platforms is that satisfy these conditions.

Regards

Christoph

http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/cludwig.html LiDIA: http://www.informatik.tu-darmstadt.de/TI/LiDIA/Welcome.html

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