On 16/06/15 23:37, 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). > > - the majority of packages using c++98 or earlier c++ standards > should just continue to work. > - In GCC 4.9 and earlier versions the libstdc++6 C++11 support was > still marked as experimental, and upstream doesn't (and didn't in the past) > guarantee c++11 ABI compatibility across major GCC versions. > It worked somehow ok in the past, however it won't this time. > - some c++98 code won't work when parts are built using GCC 4.9, and some > parts with GCC 5 (see PR66145 upstream). > > Unfortunately due to PR66145 we already have an incompatible libstdc++6 (at > least for some packages) in testing/unstable, which was only seen after the > first packages were rebuilt and issues like #784655 were reported. > > 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. > > Details for the whole transition are outlined in > > https://wiki.debian.org/GCC5 > > I'd appreciate feedback for this plan, clarify the wiki page, and would like > to > post a finalized plan next week to d-d-a, and file appropriate transition bugs > next week.
Hi Matthias, Thanks for the report. I have looked at the wiki page, but it's not entirely clear to me how the libstdc++ transition will go, so I have a few questions to better understand it. - You suggest that some libraries may need to be renamed due to the ABI breaks. Do you have a list of affected libraries? - Will those libraries need to migrate all at the same time with libstdc++, or could libstdc++/gcc-5 migrate first, and then the libraries can slowly migrate independently? My main concern with all this is if we'll have a huge transition with lots of libraries been renamed and having to migrate at the same time with their rdeps. Cheers, Emilio -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/558bc883.1060...@debian.org
