We haven't had one of these for a few years, a C++ ABI transition. GCC is changing to version 5 and the symbols it makes for C++ libraries are changing with it.
Hopefully most libraries won't need a change but it'll probably need .symbols files to be updated Some libraries will need a whole new name and soversion, we don't know how many, hopefully not many, Please hold off on uploading stuff to wily until this is done. More information at https://wiki.debian.org/GCC5#libstdc.2B-.2B-_ABI_transition CI train at https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-016/+packages Jonathan ---------- Forwarded message ---------- From: Matthias Klose <[email protected]> Date: 7 July 2015 at 20:56 Subject: GCC 5 / libstdc++ transition To: ubuntu-devel <[email protected]> Hi, GCC 5 will be the default compiler for the wily release, and it's time to prepare the change of the default in wily, so that we don't have to do it during the next relase cycle before the next LTS release. This time things are a bit more complicated, we basically need to rebuild all C++ packages using g++ 5, and we are not able to fall back to a newer compiler. For some C++11 language requirements, changes on some core C++ classes are needed, resulting in an ABI change. As the benefit, stable and complete C++11 standard support is provided by GCC 5. Details of the transition plan are documented in the Debian wiki, and I'm trying to get this transition going in Debian at the same time, however if it's delayed there, we'll need to go ahead to be able to finish the transition before the wily release. For a short introduction: Read https://wiki.debian.org/GCC5 Bugs (only filed for Debian, which need fixing): https://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=ftbfs-gcc-5;[email protected] https://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=libstdc%2B%2B-cxx11;[email protected] To cite from the email to debian-devel-annonuce [1]: """ How can you help? - Don't wait until GCC 5 is the default, start fixing and helping now. - Please fix the above mentioned GCC 5 issues. Consider uploading the fix in a NMU. - Investigate if followup transitions for libraries are needed. - Upload packages which have a patch, but no feedback from the package maintainers. - Please don't ask if the GCC maintainers can rebuild your package when you didn't check that for yourself when uploading a new upstream version. - Join #debian-toolchain on OFTC to coordinate uploads, and ask questions. At least Martin Michlmayr (tbm) and myself (doko) will be there. The libstdc++6 transition will be a large one, having a large fun/pain factor depending on your point of view. In either case, please help it by addressing the outstanding issues. """ Of course you can ask question on irc in #ubuntu-devel (Freenode) as well. The top priority will be to fix most issues before GCC 5 becomes the default. So please send patches for the outstanding Debian issues. A list of build failures with GCC 5 for packages only in Ubuntu can be found at http://people.ubuntuwire.org/~wgrant/rebuild-ftbfs-test/test-rebuild-20150402-gcc5-vivid.html I am asked to prepare this transition using the CI train, using the PPA in https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/landing-016 This PPA will contain the GCC packages defaulting to GCC 5 and defaulting to the new libstdc++ ABI (for now you can find these in the ubuntu-toolchain-r PPA). Using the CI train has the advantage: - build a package or a set of packages that can be tested first, before being uploaded to -proposed. It has the disadvantage: - to keep the packages in this ppa in sync with the uploads into -proposed. According to http://people.canonical.com/~ubuntu-archive/transitions/html/libstdc++6.html we'll have to keep track of 3500 source packages. - limiting upload rights to this PPA to core developers - porting tools like the transition tracker and britney to work with PPA's I'm not yet sure that this strategy is the one with the least amount of work, however what I can say that it increases the amount of work for me and maybe others. So I'm asking these people spending less work to help with keeping the PPA up to date (which will be difficult too, because most people in these teams are not core developers. phone/phablet guys, it's you). So please start fixing open issues *now*, and prepare for some time for bug fixing instead of the beach in July and August ;-P Matthias [1] https://lists.debian.org/debian-devel-announce/2015/07/msg00000.html -- ubuntu-devel mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel -- kubuntu-devel mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/kubuntu-devel
