On 31 May 2012 22:35, James Y Knight wrote: > You've missed at least one ABI incompatibility in GCC 4.7 and later, as > demonstrated in real life by (at least) libboost_python, and distilled > into this test case. > > At least these bug reports are probably caused by this ABI incompatibility: > https://svn.boost.org/trac/boost/ticket/6919
That appears to be a strict aliasing violation. Boost.Python has lots of warnings about them when built. > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53455 > https://svn.boost.org/trac/boost/ticket/6895 > > As I've said before, I really wish GCC devs would take the ABI > incompatibility problem more seriously. Those two reports and your test case are the same as http://gcc.gnu.org/PR53646 and http://gcc.gnu.org/PR53657 and should be fixable. It might also be the cause of http://gcc.gnu.org/PR53490 (I couldn't reproduce that one so I'm not sure.) It seems to be an inadvertent incompatibility caused by the interaction of a libstdc++ workaround for a bug and g++ behaviour that may not have been known to the libstdc++ devs, so not something that could have been prevented by making it a linker error, because noone knew it was even broken. Testing and reporting bugs and analysing the problem should lead to it being fixed. I think the problem was GCC devs not knowing the problem existed, rather than not taking it seriously.
