On 06/17/2015 09:42 PM, Lisandro Damián Nicanor Pérez Meyer wrote: > On Tuesday 16 June 2015 23:37:41 Matthias Klose wrote: >> Hi, >> >> it's time to prepare for GCC 5 as the default compiler in unstable. >> Compared to earlier version bumps, the switch to GCC 5 is a bit more >> complicated because libstdc++6 sees a few ABI incompatibilities, partially >> depending on the C++ standard version used for the builds. libstdc++6 will >> support two ABI's, the classic cxx98 ABI (currently in testing/unstable) >> and the new cxx11 ABI (currently enabled in experimental as the default >> ABI). > > Hi Matthias! > > [snip] > >> My goal is to make the GCC version bump in early July, and use the time >> until then to prepare libstdc++6 depending packages to get ready for GCC 5, >> and avoiding version bumps for C++ libraries until this time. > > As you already know we the Qt/KDE team, in order to avoid an ABI break, need > to either: > > a) Push Qt 5.4.2 to unstable before gcc5 becomes the default compiler. This > is > currently not an option due to #787689. > > b) Push Qt 5.4.2 to unstable at the same time as gcc5 becomes the default > (well, one or two dinstalls later maybe). If some package gets compiled with > gcc5 and Qt < 5.4.2 in the meantime we can binNMU it. > > c) Push Qt 5.4.2 to unstable a couple of days before gcc5 becomes the > default. > Once gcc5 becomes the default ask for a give back in armhf. > > d) Push Qt 5.4.2 to unstable either by forcing gcc5 as default at build time > or working around the bug. I would definitely would like to avoid this option > as: > - The current Qt stack is comprised of 25 source packages. I don't think me > or my teammates will have the time to hack all of them before beginnings > of July. > - I don't know if some other lib/app that build depends on qt5 will still > have the issue on armhf if we workaround it. > - I don't know what happens if Qt5 gets built against gcc5 but apps against > gcc4.9. Possibly and hopefully nothing, but I just don't know. > > My current preference would be acb (totally discarding d), but I'm open to > suggestions too.
I would prefer b), and preparing the packages to build with the gcc-5 from experimental (not unstable). Does Qt 5.4.2 change sonames? If not, please prepare to change the library package names, if new cxx11 symbols are introduced. Matthias -- http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/pkg-kde-talk