kdecoration2 mess - std::function makes the world fun

[Matthias Klose]

On 08/20/2015 04:08 PM, Sune Vuorela wrote:
> Hi Release Team, hi pkg-kde (and a couple of BCC's just as a FYI)
> 
> (not subscribed to -release, please CC me)
> 
> After having spent quite some time today looking at the current kdecoration2 
> mess (tracked at https://bugs.kde.org/show_bug.cgi?id=350964 ,  at 
> debian:796194, debian:796184 and probably many more)
> 
> The crash happens around when a std::function (a c++11 feature) is passed 
> across a library boundary and some parts of it is built with gcc5 and others 
> with 4.9.
> 
> According to Matthias Klose, upstream actually gives no guarantees for for 
> their abi for c++11, so I guess the steps forward should be:

just to clarify. The c++11 support in GCC versions up to 4.9.x was declared as
experimental.  Upstream didn't make any guarantees for it's compatibility across
major GCC versions, including the changes to GCC 5.  In GCC 5 the c++11 support
is now called stable, and the upstream promise is that future libstdc++ releases
should be compatible.

> 1) Immediately binNMU src:kdecoration2 in testing, then when that is done, 
> binNMU src:kwin, src:oxygen and src:breeze all in testing. (that's for release 
> team)

this won't work, the GCC 5 in testing is not built using the dual libstdc++ ABI.
GCC 5.2 is not yet in testing.

> 2) At the same time, do a library transition for libkdecoration2-5 and rename 
> it to libkdecoration2-5v5 and binNMU the rdeps (the same as mentioned above)

either this, or add breaks to the reverse dependencies, as done with the PR66145
issues
(http://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=gcc-pr66145;users=debian-gcc@lists.debian.org)

Matthias