Hello Pythonistas, the pyproject-rpm-macros-0-51 update (available in Rawhide+ELN and updates ready for 33 and 34) introduces a new provisional %{pyproject_build_lib} macro.
The intended use case will remain the same, but it might yet change its behavior slightly. Here is the snippet from pyproject-rpm-macros README, better viewed at https://src.fedoraproject.org/rpms/pyproject-rpm-macros/blob/rawhide/f/READM...
PROVISIONAL: Importing just-built (extension) modules in %build ---------------------------------------------------------------
Sometimes, it is desired to be able to import the *just-built* extension modules in the `%build` section, e.g. to build the documentation with Sphinx.
%build %pyproject_wheel ... build the docs here ...
With pure Python packages, it might be possible to set `PYTHONPATH=${PWD}` or `PYTHONPATH=${PWD}/src`. However, it is a bit more complicated with extension modules.
The location of just-built modules might differ depending on Python version, architecture, pip version. Hence, the macro `%{pyproject_build_lib}` exists to be used like this:
%build %pyproject_wheel PYTHONPATH=%{pyproject_build_lib} ... build the docs here ...
This macro is currently **provisional** and the behavior might change.
The `%{pyproject_build_lib}` macro expands to an Shell `$(...)` expression and does not work when put into single quotes (`'`).
Depending on the pip version, the expanded value will differ:
### New pip 21.3+ with in-tree-build (Fedora 36+)
Always use the macro from the same directory where you called `%pyproject_wheel` from. The value will expand to something like:
* `/builddir/build/BUILD/%{name}-%{version}/build/lib.linux-x86_64-3.10` for wheels with extension modules * `/builddir/build/BUILD/%{name}-%{version}/build/lib` for pure Python wheels
If multiple wheels were built from the same directory, some pure Python and some with extension modules, the expanded value will be combined with `:`:
* `/builddir/build/BUILD/%{name}-%{version}/build/lib.linux-x86_64-3.10:/builddir/build/BUILD/%{name}-%{version}/build/lib`
If multiple wheels were built from different directories, the value will differ depending on the current directory.
### Older pip with out-of-tree-build (Fedora 34, 35, and EL 9)
The value will expand to something like:
* `/builddir/build/BUILD/%{name}-%{version}/.pyproject-builddir/pip-req-build-xxxxxxxx/build/lib.linux-x86_64-3.10` for wheels with extension modules * `/builddir/build/BUILD/%{name}-%{version}/.pyproject-builddir/pip-req-build-xxxxxxxx/build/lib` for pure Python wheels
Note that the exact value is **not stable** between builds (the `xxxxxxxx` part is randomly generated, neither you should consider the `.pyproject-builddir` directory to remain stable).
If multiple wheels are built, the expanded value will always be combined with `:` regardless of the current directory, e.g.:
* `/builddir/build/BUILD/%{name}-%{version}/.pyproject-builddir/pip-req-build-xxxxxxxx/build/lib.linux-x86_64-3.10:/builddir/build/BUILD/%{name}-%{version}/.pyproject-builddir/pip-req-build-yyyyyyyy/build/lib.linux-x86_64-3.10:/builddir/build/BUILD/%{name}-%{version}/.pyproject-builddir/pip-req-build-zzzzzzzz/build/lib`
**Note:** If you manage to build some wheels with in-tree-build and some with out-of-tree-build option, the expanded value will contain all relevant directories.