David Abrahams wrote: >>When I looked into this problem I saw that configure in fact builds a test >>executable that included an object file compiled with g++. If the link step >>with gcc succeeds then LINKCC is set as above, otherwise CXX is >>used. Obviously, on my system this test was successful so configure decided >>to link with gcc. However, minimal changes to the source of the test program >>caused the link step to fail. It was not obvious to me at all why the latter >>source code should cause a dependency on the C++ runtime if the original >>code does not. My conclusion was that this test is fragile and should be >>skipped. > > > Sounds like it. I have never understood what the test was really > checking for since the moment it was first described to me, FWIW.
I'll describe it once more: *If* a program is compiled with the C++ compiler, is it *then* possible to still link it with the C compiler? This is the question this test tries to answer. >>If Python is built with --with-cxx then it should be linked with CXX >>as well. > > > U betcha. Wrong. The test was introduced in response to complaints that Python unnecessarily links with libstdc++ on some Linux systems. On these Linux systems, it was well possible to build main() with a C++ compiler, and still link the entire thing with gcc. Since main() doesn't use any libstdc++ functionality, and since collect2/__main isn't used, one would indeed expect that linking with CXX is not necessary. >>(On ELF based Linux/x86, at least.) That leaves me wondering >> >> * when is --with-cxx really necessary? > > > I think it's plausible that if you set sys.dlopenflags This has no relationship at all. --with-cxx is much older than sys.dlopenflags. It is used on systems where main() must be a C++ program for C++ extension modules to work (e.g. some Linux systems). Regards, Martin _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
