llvm-3.9 "new libstdc++ ABI compatibility"

[Lawrence Velázquez]

> On Sep 2, 2016, at 1:25 PM, René J.V. Bertin <rjvbertin at gmail.com> wrote:
> 
> Just caught this in the llvm-3.9 release message: "new libstdc++ ABI compatibility".
> 
> I guess we'll be seeing port:llvm-3.9 provide 3.9.0 in a near future, but what does that ABI remark mean for us on OS X? Will it again be easier to build C++ code using GCC?

No.

> Or will it be easier for older OS X versions to migrate to libc++?

No.

> Or is it something that will in fact mostly/only benefit Linux users?

Yes. This is meant to keep Clang compatible with ABI changes to GCC 5.1's libstdc++.

http://llvm.org/releases/3.9.0/docs/ReleaseNotes.html#gcc-abi-tag
https://llvm.org/bugs/show_bug.cgi?id=23529

vq

P.S. Incidentally, this implies that g++ 4.x is also ABI-incompatible with libstdc++ 5.1. Have we encountered any issues along these lines?