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f33e652
(Get the code!)
Following up on the Linaro Toolchain list[1], I found out a few facts:
1. This feature was implemented in GCC and libstdc++ in 2012, after discussions on the cauldron with distro representatives.
2. The feature is poorly documented, and may have changed behaviour until recently. I have no evidence of changes, is anyone does, please update.
3. The problem only started because distros have chosen GCC 5 as their default compilers for the current releases, which defaults to C++11.
4. The fact that GCC developers didn't liaise with Clang developers is a shame, but understandable. The real issue here is the fact that distro representatives took an executive decision to change the object layout of core C++ classes in libstdc++ and to change the ABI without worrying about other compilers.
If they has asked Clang folks about the ABI change, (and they did, see this thread), they would have known that the ABI behaviour was poorly documented and a moving target (as they did, look at this bug), and should have taken the decision to mitigate the problems.
In this case, I'd expect distro folks to be the middle-men between GCC and Clang and to make sure that both compilers work well on their new releases. If you look at this bug and all of those that were marked as duplicate, you'll see that both Debian and RedHat based distros knew that Clang still didn't have the feature they needed and why.
True, we could have been more informative and made explicit every detail on why it was hard to know what to implement, but as middle-men, I expected distros to be more pro-active towards unification and less pro-active towards changing the ABI.
[1] https:/