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Feature Request

pypi.org recommends:

To prevent a package from being uploaded to PyPI, use the special "Private :: Do Not Upload" classifier. PyPI will always reject packages with classifiers beginning with "Private ::".

The same recommendation is also published on packaging.python.org.

When validating a pyproject.toml file with the following, poetry check will fail.

classifiers = [
    "Private :: Do not Upload",  # Prevent uploading to PyPI
]

Error message:

Error: Unrecognized classifiers: ['Private :: Do not Upload'].

This is correct behaviour for projects that are intended to be uploaded to PyPI.

However, there are projects that are not intended to be uploaded to PyPI and follow the above recommendation. How should those projects validate their pyproject.toml?

Suggestions

1. Would it be reasonable to add an option such as --allow-private-classifiers to poetry check? This option could allow classifiers with the prefix "Private ::".
2. See Implement private projects #1537 which discusses a number of alternatives to "Private :: Do not Upload". Possibly one of these alternatives could be used as a flag which, if present, adds the "Private :: Do not Upload" classifier to the built package.