GCC version bikeshedding

[Jonathan Wakely]

On 6 August 2014 10:06, Jakub Jelinek wrote:
> On Wed, Aug 06, 2014 at 11:04:14AM +0200, Richard Biener wrote:
>> > - libstdc++ ABI changes (it is a significant user visible change,
>> >   if you rebuild everything, no extra effort is needed, but otherwise
>> >   if you want some C++ code built with older compilers work together
>> >   with code built with newer compilers, it might require source code
>> >   changes (the abi_tag attribute additions where needed and warning
>> >   suggest to put those at), at least that is my current understanding
>> >   of the plans
>>
>> But that's only with -std=c++11?  Which had no compatibility
>> guarantees before?
>
> No, AFAIK it is also -std=c++98.  At least my understanding was that
> std::list and std::string are going to change ABI (and get new abi_tag)
> in all C++ modes.  Jonathan/Jason/Paolo, is that right?

Correct. We want C++03 code to continue to be able to interoperate
with C++11 code.

It's an ABI change for all modes (but not a SONAME change because the
old and new definitions will both be present in the .so).