Positional-only parameters are only supported in Python 3.8 and greater

[ribeaud]

Describe the bug
I have a project running mypy on panda-stubs.

To Reproduce
See https://gitlab.com/biomedit/sett/-/jobs/3016695046:

$ mypy
/usr/local/lib/python3.10/site-packages/pandas-stubs/_config/config.pyi:28: error: Positional-only parameters are only supported in Python 3.8 and greater
Found 1 error in 1 file (errors prevented further checking)

Please complete the following information:

• OS: macOS
• OS Version: 12.6
• python version: 3.10.7
• version of type checker: mypy v0.971
• version of installed pandas-stubs: 1.4.4.220912

[bashtage]

I think Python 3.7 is no longer a target of pandas.

[bashtage]

I think Python 3.7 is no longer a target of pandas.

[ribeaud]

But I am using 3.10.7.

[bashtage]

I'm suggesting that if you want typing you need to migrate to a Python released in the past 4 years.

[ribeaud]

Sorry, I do not get it. As specified in the report, I am using Python v3.10.7, so a py310 release.

[bashtage]

Ahh, sorry. Why are you reporting this bug?

[ribeaud]

mypy is triggering an error and makes my build fail. This is pretty new and probably related to a newer release of mypy.

So, either this is a bug in mypy (up to my experience, this is pretty rar) or there is some issue at line 28 of file config.pyi. No?

[Dr-Irv]

@ribeaud You'd have to be able to replicate this with a simple example. We tested the stubs with python 3.10, and do not get that error message. It could be something to do with the mypy settings in your CI, or some other strange interaction with your CI environment and our stubs.

While the message is saying that positional parameters are only supported in python 3.8 or greater, and you are using python 3.10 based on the location of the installation of the stubs, there is something else going on in your environment.

[ribeaud]

OK, thank you for testing and sorry for the disturbance. I will check my environment...

[twoertwein]

Do you have something like python_version = "3.7" in your mypy config file?

[ribeaud]

Seems to be a v3.10.7 specific problem:

• Positional-only parameters with python 3.10.7 (and numpy) (fixed in 0.981) python/mypy#13627
• Mypy in 3.10 does not respect the python version when checking .pyi files python/mypy#13635
• pypy3.9 - SyntaxError due to positional only arguments in stubfile python/mypy#13499
• Mypy (running in 3.10) complains that positional-only parameters are only supported in 3.8+ python/mypy#13639

[bashtage]

Thanks for checking and following up.