Stubs that require a version of python higher than the minimum supported by typeshed

[hamdanal]

In #10721, the seaborn stubs depend on matplotlib that only included a py.typed marker file in version 3.8.
matplotlib version 3.8 requires python >=3.9 which leads to the mypy tests failing on python 3.8.

Alex Waygood suggests adding a requires-python field to METADATA.toml and teaching stub-uploader to include it in the generated setup.py #10721 (comment).

Please let us know what you think about this idea or if you have another solution.

[AlexWaygood]

I think this would be a good idea.

We actually already have a need for this: typeshed claims to support Python 3.7+, but the latest version of types-jsonschema will only work with mypy on Python 3.8+. The only reason why this isn't causing our CI to fail is that we no longer run mypy in CI on Python 3.7, because the latest version of mypy only supports Python 3.8+. But that isn't particularly principled; we should signal to our users that the stubs package we're shipping only works with Python 3.8+, by including that information in the generated setup.py file.

[AlexWaygood]

Oh, actually, the types-jsonschema PR I was thinking of hasn't been merged yet... the package will require Python 3.8+ if #10583 is merged :-)

[hamdanal]

Should the field be empty by default or should it be set to typeshed's minimum supported python?

[AlexWaygood]

The METADATA.toml field should be optional — the default assumption should be that most stubs packages can be used with all versions of Python that typeshed supports.

We should add some validation to tests/parse_metadata.py to ensure that we don't have any requires-python fields that specify a minimum Python version less than the oldest version of Python supported by typeshed.

I'm not sure what the stub uploader should do if it encounters a stubs package that doesn't have a requires-python field in METADATA.toml. Should it add requires-python to the generated setup.py file anyway, and set it to the lowest version of Python supported by typeshed? Or should it just not add anything to the setup.py file?

[AlexWaygood]

I'm not sure what the stub uploader should do if it encounters a stubs package that doesn't have a requires-python field in METADATA.toml. Should it add requires-python to the generated setup.py file anyway, and set it to the lowest version of Python supported by typeshed? Or should it just not add anything to the setup.py file?

Answering my own question after thinking about this a little more: I think it should add requires-python to the generated setup.py file anyway, and set it to the lowest version of Python supported by typeshed. Here's why: in January 2024, we'll be dropping support for Python 3.7 (#10113), and when we do so, we'll likely start using PEP-570 syntax across most of typeshed. That will make most of our stubs packages incompatible with Python 3.7, even the ones that don't have any external dependencies. It will be important to signal this to our users.

[hamdanal]

That will make most of our stubs packages incompatible with Python 3.7, even the ones that don't have any external dependencies. It will be important to signal this to our users.

Makes sense.

[hamdanal]

Required tasks:

• Allow requires_python field in METADATA.toml Add optional requires_python to third party stubs metadata #10724
• Add oldest_supported_python field, the minimal version of Python supported by typeshed, to pyproject.toml Add optional requires_python to third party stubs metadata #10724
• Update mypy_test to skip unsupported versions Add optional requires_python to third party stubs metadata #10724
• Update regr_test to skip unsupported versions Add optional requires_python to third party stubs metadata #10724
• Update stubtest_third_party to skip unsupported versions Add optional requires_python to third party stubs metadata #10724
• Document the new requires_python field in https://github.com/python/typeshed/blob/main/CONTRIBUTING.md#the-metadatatoml-file
• Update pyright_test to skip unsupported versions
• Update pytype_test to skip unsupported versions (pytype support removed in Remove support for pytype #14463)
• Update the runtests script (Support requires_python in runtests.py #14051)
• Update stub_uploader to include the field in the PyPI distributions Add a "requires-python" metadata field in stub distributions typeshed-internal/stub_uploader#103

[Avasam]

Since this issue touches that area.
Example scenario that we'd like to avoid in runtests and that using per-stubs python version would help with instead of always running on 3.8:
https://github.com/python/typeshed/actions/runs/6347797998/job/17243343457?pr=10801
I imported Final from the wrong location, ran the scripts locally which told me it was all good on Python 3.8+. But it failed on the CI on Python 3.7.

[hamdanal]

I just took a quick look on the pyright and pytype scripts. The problem here is that these tests run on the whole project. They have to become modular somehow before applying the same logic of skipping tests in mypy and stubtest. This is a bigger change than what we did with mypy.

As for the specific issue you got, maybe there is a ruff rule that replaces or bans certain imports?