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title
| title |
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| Modern C++ standards |
Building Python wheels with modern C++ standards (C++11 and later) requires a few tricks.
Python 2.7 and C++17
The Python 2.7 header files use the register keyword, which is reserved and unused from C+17 onwards. Compiling a wheel for Python 2.7 with the C++17 standard is still possible to allow usage of register using proper flag -Wno-register for gcc/clang and /wd5033 for MSVC.
manylinux1 and C++14
The default manylinux1 image (based on CentOS 5) contains a version of GCC and libstdc++ that only supports C++11 and earlier standards. There are however ways to compile wheels with the C++14 standard (and later): https://github.com/pypa/manylinux/issues/118
manylinux2010 and manylinux2014 are newer and support all C++ standards (up to C++17).
macOS and deployment target versions
OS X/macOS allows you to specify a so-called "deployment target" version that will ensure backwards compatibility with older versions of macOS. One way to do this is by setting the MACOSX_DEPLOYMENT_TARGET environment variable.
However, to enable modern C++ standards, the deploment target needs to be set high enough (since older OS X/macOS versions did not have the necessary modern C++ standard library).
To get C++11 and C++14 support, MACOSX_DEPLOYMENT_TARGET needs to be set to (at least) "10.9". By default, cibuildwheel already does this, building 64-bit-only wheels for macOS 10.9 and later.
To get C++17 support, set MACOSX_DEPLOYMENT_TARGET to (at least) "10.13" or "10.14" (macOS 10.13 offers partial C++17 support; e.g., the filesystem header is in experimental, offering #include <experimental/filesystem> instead of #include <filesystem>; macOS 10.14 has full C++17 support).
For more details see https://en.cppreference.com/w/cpp/compiler_support and https://xcodereleases.com/: Xcode 10 needs macOS 10.13 and Xcode 11 needs macOS 10.14.
Windows and Python 2.7
Visual C++ for Python 2.7 does not support modern standards of C++. When building on Appveyor, you will need to either use the "Visual Studio 2017" or "Visual Studio 2019" image, but Python 2.7 is not supported on these images - skip it by setting CIBW_SKIP=cp27-win*.
There is an optional workaround for this, though: the pybind11 project argues and shows that it is possible to compile Python 2.7 extension with a newer compiler and has an example project showing how to do this: https://github.com/pybind/python_example. The main catch is that a user might need to install a newer "Microsoft Visual C++ Redistributable", since the newer C++ standard libraries are not included by default with the Python 2.7 installation.