On Thursday, 19 December 2013 10:18:55 CEST, Michał Górny wrote:
Would it be possible to have a consistent ABI for both C++03 and C++11? The simpler changes like adding new fields can be backported quite easily (even if it would mean having dummy fields in C++03), I have no idea about the more complex changes.
I don't know, but from a bystander's point of view, I surely hope that it will be possible. Otherwise there would be no option but providing a multilib-like setup for C++11, after all.
Some messages on gcc's ML indicate that there are software vendors who are *very* afraid of doing the SONAME change again. Given that C++11 forbids a refcounted std::string while libstdc++ currently use just that for its implementation, I suspect that the upstream developers have a very interesting problem to solve. (And there's much more.)
It is pretty clear to me that even the gcc people have not reach a consensus on how the ABI of the standard library will look like in 4.9, so maybe it is premature for us to talk about how to solve this. The ball is on their side.
Well, if they considered the C++11 ABI in gcc-4.9 stable, we could consider changing the default to C++11. Then, we could do our bump/switch thing as a matter of gcc-4.9 upgrade problem.
To put things into perspective, *if* the ABI changes and if the new version is compatible between C++98 and C++11, then we're talking something very similar to an upgrade from GCC 3.3.
Cheers, Jan
