Allow including data files in wheels, configured through
`pyproject.toml`. This configuration is currently only read in the build
backend. We'd only start using it in the frontend when we're adding a
fast path.
Each data entry is a directory, whose contents are copied to the
matching directory in the wheel in
`<name>-<version>.data/(purelib|platlib|headers|scripts|data)`. Upon
installation, this data is moved to its target location, as defined by
<https://docs.python.org/3.12/library/sysconfig.html#installation-paths>:
- `data`: Installed over the virtualenv environment root. Warning: This
may override existing files!
- `scripts`: Installed to the directory for executables, `<venv>/bin` on
Unix or `<venv>\Scripts` on Windows. This directory is added to PATH
when the virtual environment is activated or when using `uv run`, so
this data type can be used to install additional binaries. Consider
using `project.scripts` instead for starting Python code.
- `headers`: Installed to the include directory, where compilers
building Python packages with this package as built requirement will
search for header files.
- `purelib` and `platlib`: Installed to the `site-packages` directory.
It is not recommended to uses these two options.
For simplicity, for now we're just defining a directory to be copied for
each data directory, while using the glob based include mechanism in the
background. We thereby introduce a third mechanism next to the main
includes and the PEP 639 mechanism, which is not what we should finalize
on.
When building source distributions, we need to include the readme, so it
can become part the METADATA body when building the wheel. We also need
to support the license files from PEP 639. When building the source
distribution, we copy those file relative to their origin, when building
the wheel, we copy them to `.dist-info/licenses`.
The test for idempotence in wheel building is merged into the file
listing test, which also covers that source tree -> source dist -> wheel
is equivalent to source tree -> wheel, though we do need to check for
file inclusion stronger here.
Best reviewed commit-by-commit
A first milestone: source tree -> source dist -> wheel -> install works.
This PR adds a test for this.
There's obviously a lot still missing, including basics such as the
Readme inclusion.
