useless-type-doc conflicts with mypy no-untyped-def, unsure how to proceed

[nth10sd]

With pylint 2.7.0, we now have the useless-type-doc check. I also have disallow_untyped_defs = True turned on for mypy.

I have some functions with unused variables that I append a _ to the name, e.g. _name and set a type to them. pylint 2.7.0 now throws useless-type-doc error, and when I remove the type, mypy throws the no-untyped-def error.

What's the best way forward? Should I change the mypy config, or should I ignore this pylint error?

This worked with pylint 2.6.x, since it does not have the useless-type-doc check.

[Pierre-Sassoulas]

Hello, thank you for opening the issue.

Do you have a code example so I can understand the problem better ?

(You can disable the pylint message with # pylint: disable=useless-type-doc for now in order to not be stuck in an infinite loop while we figure this out.)

[nth10sd]

Sample:

"""module docstring"""


def test(_new) -> str:
    """foobar

    :return: comment
    """
    return ""


def main() -> None:
    """main function"""
    test("")

I have the following settings:

mypy.ini : disallow_untyped_defs = True or use --disallow-untyped-defs in CLI
.pylintrc:

[MASTER]
load-plugins=pylint.extensions.docparams,

[PARAMETER_DOCUMENTATION]
accept-no-param-doc=no
accept-no-raise-doc=no
accept-no-return-doc=no
accept-no-yields-doc=no

$ mypy --disallow-untyped-defs start.py
start.py:4: error: Function is missing a type annotation for one or more arguments
Found 1 error in 1 file (checked 1 source file)
$ pylint --rcfile=../.pylintrc start.py
$

However, when I change the test() function definition line to def test(_new: str) -> str:

$ mypy --disallow-untyped-defs start.py
Success: no issues found in 1 source file
$ pylint --rcfile=../.pylintrc start.py
************* Module start
start.py:4:0: W9020: "_new" useless ignored parameter type documentation (useless-type-doc)

I'm guessing these two settings --disallow-untyped-defs and useless-type-doc are naturally incompatible with each other?

$ pylint --version
pylint 2.7.0
astroid 2.5
Python 3.8.5 (default, Jul 28 2020, 12:59:40)
[GCC 9.3.0]
$ mypy --version
mypy 0.812

[nth10sd]

I'm still hitting this in pylint 2.8.3 and astroid 2.5.6 (I have ignore lines though). I've updated my settings file above, as I had regrettably missed this part out:

[MASTER]
load-plugins=pylint.extensions.docparams,

@Pierre-Sassoulas do you mind testing to see if you can reproduce this?

[Pierre-Sassoulas]

I had some time to look at this, I think this is a false positive in pylint, Another issue for this is #4593