On Fri, May 15, 2015 at 10:36:36AM -0500, Bruce Dubbs wrote: > Pierre Labastie wrote: > >Today is slightly less busy for me and I have some time to study the new gcc > >5. > >as already noted in > >http://lists.linuxfromscratch.org/pipermail/blfs-dev/2015-April/030081.html, > >there is an ABI change in the libstdc++ library. The old behavior can be > >preserved, though, because all the symbols (old and new) are contained in the > >libstdc++.so shared object. However this is not true of other libraries built > >using C++. The difference between old and new behavior just amounts to > >change a > >#define in the header files. This can be set at build time using the switch > >"--with-default-libstdcxx-abi" in configure. > > > >So: > >a) if you have built part or all of LFS/BLFS with gcc-4.9.2, and want to > >update > >to gcc-5.1.0, you need to use "--with-default-libstdcxx-abi=c++98" in order > >to > >preserve the old behavior. Otherwise, newly built packages using C++ will > >not be > >able to use old libraries built using C++. > >b) if you have built from scratch using gcc-5.1.0, you need to use > >"--with-default-libstdcxx-abi=c++11" (or nothing since it is the default). > > > >Now the question is: should I assume hypothesis a) or hypothesis b) for GCC > >in > >BLFS? In case a), I would put the flag in the instructions and mention that > >it > >can be removed in "command explanations". In case b), I would not put the > >flag > >in the instructions and mention it in the "command explanations". Or put in > >another way: should I assume that an user building BLFS-development builds > >upon > >LFS-7.7, or upon LFS-development? Actually, I presently am in the first case > >(but of course, I can rebuild to be in a second case). > > Please assume that LFS was built with gcc-5 (case b). In addition to > putting the switch in "command explanations", I think a <caution> explaining > the issue just before configure would help emphasize the issue. > > -- Bruce > Agreed. Sounds like a good solution.
ĸen -- Nanny Ogg usually went to bed early. After all, she was an old lady. Sometimes she went to bed as early as 6 a.m. -- http://lists.linuxfromscratch.org/listinfo/blfs-dev FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
