Use SPDX license names as classifiers

[ralf-vogel]

What's the problem this feature will solve?

For the license clearing of a product, it is vital to know the exact license a package is using.
Currently the packages can define classifiers like:

License :: OSI Approved :: MIT License
License :: OSI Approved :: BSD License

or just:

License :: OSI Approved

This is very unspecific and raises some important questions.
What BSD License does this refer to?
SPDX lists 32 different BSD licenses.
Or even worse: what OSI Approved license is this package using?
There is a huge difference between the MIT License and the GNU General Public License v2.0 or later (especially regarding the copyleft).

So the classifiers might look useful, but in many cases they are not.

The solution I would like

Instead of the unprecise classifiers above, the the packages should be labelled with unique license identifiers matching the full names in the SPDX License List.
This also means, that the group License :: OSI Approved should not be a valid classifier.

[di]

Duplicate of pypa/trove-classifiers#17.

[ralf-vogel]

FYI: the actual discussion about this topic has moved here:
https://discuss.python.org/t/pep-639-round-2-improving-license-clarity-with-better-package-metadata/12622