Python

Many Python 2 modules were removed from the distribution: packages that only provide Python 2 importable modules, if they are not used by any other package (leaf packages).

While this change should not affect regular users, it will affect developers that use system-packaged Python modules.

If you are developing software that needs to run with Python 2, we recommend using a virtual environment and installing dependencies from the Python Package index (PyPI). See details at: https://developer.fedoraproject.org/tech/languages/python/python-installation.html

We also recommend using a virtual environment (venv) for Python 3, if your software targets the wider Python ecosystem rather than Fedora specifically. Using venv will decouple your development environment from the system.

If you are developing for a Fedora package, please port to Python 3 as soon as possible. Almost complete Python 2 removal is planned for the next release.

The generator which generates Provides and Requires for Python RPM packages based on the setup.py file has been enabled by default. This makes the packaging of Python packages easier and more automatic by reusing information provided by the upstream project, and should result in fewer unecessary or missing dependencies in RPMs.

The progressbar package has been updated to use the progressbar2 fork, which is newer and better maitained.

As part of the general move to Python 3, extensions for the file browser and graphical shell Nautilus are now executed using Python 3, and extensions compatible only with Python 2 are no longer supported. Extensions packaged in the distribution have been updated for Python 3 compatiblity. Users who have installed their own extensions should check that they are compatible with Python 3 or remove them.

When extension modules are built, the distutils module provides a set of compilation and link flags to ensure that modules are compiled in a way which is compatible with Python executable itself. When building modules in Fedora, the same set of flags was used for modules which are part of the distribution (i.e. part of an RPM package) and for modules compiled by users using Fedora. Those flags included custom GCC plugins and additional linker options to "harden" the code and add annobin annotations, which is appropriate for the distribution, but unexpected and unnecessary for user code. A distinct and smaller set of flags is now provided for extension modules compiled by users.

The build flags (CFLAGS, CXXFLAGS and LDFLAGS) saved in the Python’s distutils module for building extension modules are switched from:

to

This currently means that no GCC plugins (such as annobin) are activated and no GCC spec files (-specs= arguments) are used by default when building Python extension modules (e.g. with python3 setup.py build).

The python3-devel package will lose its runtime dependency on redhat-rpm-config (which was only required for annobin support and GCC spec files).

The change affects building extension modules by users, outside of the RPM environment. The Python standard library and Fedora’s Python 3 RPM packages are still built with the "traditional" set of flags (%{build_cflags} etc.), unless the package uses nonstandard methods to build the extensions.

Only Python 3.7 and 3.6 will be changed.

For detailed information about this change, including justification and impact on Python developers and packages, see the Change page on the Wiki.