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Re: [RFC] C++1x breaking the ABI in one more place :(
Mark Mitchell <mark@codesourcery.com> writes:
> Joe Buck wrote:
>
>> But this is a kind of breakage that might be acceptable to fix an
>> otherwise broken library (though users should be warned about it),
>> especially in cases where we wouldn't expect this kind of use.
>
> I agree -- but not without a bump in the .so number. It is a serious
> binary incompatibility, unless you can convince yourself that nobody
> derived from this class.
The vtables in libstdc++ have symbol versions. Therefore it is
possible in principle to keep the old vtable at the old symbol version
(GLIBCXX_3.4) and provide the new vtable at the new version.
Ian