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Re: C++98/C++11 ABI compatibility for gcc-4.7

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:

That appears to be a strict aliasing violation. Boost.Python has lots
of warnings about them when built.

> 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 and and should
be fixable.
It might also be the cause of (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

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