On Mon, Feb 05, 2018 at 03:17:55PM -0600, Jonathan Helmus wrote: > On 02/03/2018 02:11 AM, Nathaniel Smith wrote: > > > Docker Images > > > ------------- > > > > > > ``manylinux2`` Docker images based on CentOS 6.9 x86_64 and i686 are > > > provided for building binary ``linux`` wheels that can reliably be > > > converted to ``manylinux2`` wheels. _ These images come with a > > > full compiler suite installed (``gcc``, ``g++``, and ``gfortran`` > > > 4.8.2) as well as the latest releases of Python and ``pip``. > > We can and should use newer compiler versions than that, and probably > > upgrade them again over the course of the image's lifespan, so let's > > just drop the version numbers from the PEP entirely. (Maybe s/6.9/6/ > > as well for the same reason.) > > > > Moving to GCC 5 and above will introduced the new libstd++ ABI.  The > manylinux2 standard need to define which ABI compiled libraries should be > compiled against as older version of libstdc++ will not support the new > ABI. From what I recall the devtoolset packages for CentOS can only target > the older, _GLIBCXX_USE_CXX11_ABI=0, ABI.
Geoffrey Thomas helped to confirm that devtoolset-7 does the Right Thing here, as much as that's possible. Its libstdc++.so is actually the following linker script: # cat /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/libstdc++.so /* GNU ld script Use the shared library, but some functions are only in the static library, so try that secondarily. */ OUTPUT_FORMAT(elf64-x86-64) INPUT ( /usr/lib64/libstdc++.so.6 -lstdc++_nonshared ) The INPUT command instructs ld to search for GCC symbols in the system's libstdc++_s.so first; if they're present there, the resulting binary will load them from it at runtime, and the binary will match the ABI policy described in the PEP. If the binary requires newer symbols that aren't present in the system's libstdc++.so, ld will statically link them in from its interal libstdc++_nonshared.a. This result will also match the ABI policy, in that it will either depend only on the subset of symbols available in CentOS 6's default libstdc++.so or none at all. See the ld documentation for an explanation of INPUT: https://sourceware.org/binutils/docs/ld/File-Commands.html Geoffrey did point out that there's a potential issue if two C++ libraries end up with their own statically-linked implementations std::string or std::list, whose ABIs changed with GCC 5. If instances of these classes are allocated in a library with pre-GCC 5 versions and freed in another with post-GCC 5 versions something bad might happen (at least, that's my understanding). I'm unsure how serious this issue will be in practice but it's worth discussion! -- Mark Williams m...@twistedmatrix.com _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig