DOC: Contributor guideline should guide contributors for expected local mypy failures

[oguzhanogreden]

Location of the documentation

Location.

Documentation problem

See conversation here.

Suggested fix for documentation

This 'failing' of mypy should be noted so that inexperienced contributors don't have to Google around and experienced ones don't have to explain repeatedly.

I came across this in this context.

[oguzhanogreden]

SKIP=mypy may be the 'clean' suggestion, thanks @MarcoGorelli.

[MarcoGorelli]

Thanks @oguzhanogreden , might be good to add a line mentioning this to the "pre-commit" section of the contributing guide https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#pre-commit

[erfannariman]

take

[erfannariman]

Need some input for this, based on the discussion in gitter (see link in message by OP), we should use

SKIP=mypy git commit -m "<some message which I know should be descriptive but usually isn't>"

But this does not work for me, I had to use

git commit --no-verify -m "<some message>"

Which one are we going for and should I add to the docs?

[WillAyd]

Why not just remove mypy from the pre-commit check? I think this has been an ongoing issue with the interaction of those tools @TomAugspurger I think brought up originally

[erfannariman]

If it (mypy check) is not needed, @WillAyd 's suggestion makes more sense to me.

[WillAyd]

Another option would be to only run mypy before a push instead of on every commit. This might be achievable with specifying the stage in the config

https://pre-commit.com/

[MarcoGorelli]

Another option would be to only run mypy before a push instead of on every commit. This might be achievable with specifying the stage in the config

https://pre-commit.com/

Not sure that work would - see below

(pandas-dev) marco@marco-Predator-PH315-52:~/pandas-dev$ git fetch upstream master
From https://github.com/pandas-dev/pandas
 * branch                master     -> FETCH_HEAD
(pandas-dev) marco@marco-Predator-PH315-52:~/pandas-dev$ git reset --hard upstream/master
HEAD is now at 0159cba6e CLN: dont consolidate in indexing (#34679)
(pandas-dev) marco@marco-Predator-PH315-52:~/pandas-dev$ pre-commit run --all
black....................................................................Passed
flake8...................................................................Passed
flake8-pyx...............................................................Passed
flake8-pxd...............................................................Passed
isort....................................................................Failed
- hook id: isort
- files were modified by this hook

Fixing /home/marco/pandas-dev/web/pandas_web.py

mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

pandas/core/dtypes/generic.py:10: error: unused 'type: ignore' comment
pandas/core/resample.py:970: error: unused 'type: ignore' comment
Found 2 errors in 2 files (checked 1043 source files)

(pandas-dev) marco@marco-Predator-PH315-52:~/pandas-dev$ mypy pandas
Success: no issues found in 1024 source files

IMHO it could be removed from pre-commit - if you're adding type annotations you'll need to run mypy pandas anyway, and if you're not then its false positives are a distraction (especially for new contributors)

[TomAugspurger]

I'm fine with removing mypy from pre-commit.