`project.classifiers[10]` must be trove-classifier

[christophfink]

Describe the bug

Building the current (v0.7.11, v0.7.12) versions fails in cythonize due to an ostensibly wrong formatting of the new license descriptor in pyproject.toml, if validate-pyproject happens to be installed.

To Reproduce

Steps to reproduce the behavior

1. have validate-pyproject in your environment (e.g., when building with --no-isolation, it is not pulled in when building in a build chroot)
2. unpack the source tar
3. run python -m build

Expected behaviour

build passes successfully

System

• OS: Arch Linux (up-to-date rolling release)
• Architecture: x86_64
• Library version: 0.7.11, 0.7.12
• Python version: 3.12

Additional context

This is, at this time, an issue mostly for pushing a new PKGBUILD to the Arch AUR repository, as the recommended way of building Python packages there is to use --no-isolation. It could be circumvented. However, this is also indicative of either the BlueOak licenses not being recognised in the PyPi ontology, or of a typo somewhere, both of which should be fixed anyway

[christophfink]

You can also run validate-pyproject pyproject.toml to receive the same error.

[christophfink]

* Getting build dependencies for wheel...
Compiling src/simplification/cutil.pyx because it changed.
[1/1] Cythonizing src/simplification/cutil.pyx
validate_pyproject.api.load_builtin_plugin defines `tool.distutils` schema
validate_pyproject.api.load_builtin_plugin defines `tool.setuptools` schema
configuration error: `project.classifiers[10]` must be trove-classifier
DESCRIPTION:
    `PyPI classifier <https://pypi.org/classifiers/>`_.

GIVEN VALUE:
    "License :: OSI Approved :: Blue Oak Model License (BlueOak-1.0.0)"

OFFENDING RULE: 'format'

DEFINITION:
    {
        "type": "string",
        "format": "trove-classifier"
    }
Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 373, in <module>
    main()
  File "/usr/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 357, in main
    json_out["return_val"] = hook(**hook_input["kwargs"])
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 134, in get_requires_for_build_wheel
    return hook(config_settings)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/setuptools/build_meta.py", line 325, in get_requires_for_build_wheel
    return self._get_build_requires(config_settings, requirements=['wheel'])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/setuptools/build_meta.py", line 295, in _get_build_requires
    self.run_setup()
  File "/usr/lib/python3.12/site-packages/setuptools/build_meta.py", line 311, in run_setup
    exec(code, locals())
  File "<string>", line 31, in <module>
  File "/usr/lib/python3.12/site-packages/setuptools/__init__.py", line 103, in setup
    return distutils.core.setup(**attrs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 159, in setup
    dist.parse_config_files()
  File "/usr/lib/python3.12/site-packages/setuptools/dist.py", line 627, in parse_config_files
    pyprojecttoml.apply_configuration(self, filename, ignore_option_errors)
  File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 72, in apply_configuration
    config = read_configuration(filepath, True, ignore_option_errors, dist)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 133, in read_configuration
    validate(subset, filepath)
  File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 61, in validate
    raise ValueError(f"{error}\n{summary}") from None
ValueError: invalid pyproject.toml config: `project.classifiers[10]`.
configuration error: `project.classifiers[10]` must be trove-classifier

ERROR Backend subprocess exited when trying to invoke get_requires_for_build_wheel

[christophfink]

Sorry, closing this for now as it seems to be related to an outdated version of validate-pyproject packaged for Arch