option to enforce error codes in type: ignore comments

[DetachHead]

Feature
it would be cool if there was an option like --disallow-ignore-without-code or something that enforces error codes in type: ignore comments

Pitch
# type:ignore comments risk suppressing an unintended error, which is why it's preferred to specify the exact error code you're suppressing

[KotlinIsland]

KotlinIsland/basedmypy#11

[asears]

Would also be useful if we could use # type: ignore below comments in the python file. Seems the # type: ignore is ignored if there is a license header in this format. Might be a separate bug/issue here.

# license copyright info
"""This is a file""
# type: ignore

This works.

# type: ignore
# license copyright info
"""This is a file""

The above request seems more like a flake8 check? Maybe in https://pypi.org/project/flake8-annotations/ it would be simpler to implement?

[KotlinIsland]

@asears What are you talking about? that code looks like a syntax error with an unterminated triple-quoted string.

There are no types in that snipped so how could there be a type error?

[asears]

Just a typo in this github issue, in the full code there is a type error that isn't ignored with the first case and no typos/flake8 warnings. The problem can be reproduced by introducing a type error and trying to silence it with this:

# license copyright info
"""This is a file"""
# type: ignore

Adding the type: ignore to top of file works fine.

[JelleZijlstra]

@asears this seems unrelated to the proposal. Please open a new issue if you'd like to see a change in mypy.

[KotlinIsland]

@asears are you asking for a whole file type ignore?

In Kotlin annotations can target the file @file:Suppress("UNCHECKED_CAST")

For mypy if that's what you want configure your pyproject.toml to specify the options you want, for eg:

pyproject.toml:

[[tool.mypy.overrides]]
module = "my.module"
ignore_errors = true

[PeterJCLaw]

How should this option interact with file-level # type: ignore comments? Should those be exempt? (Currently it's not possible to specify error codes to ignore per-file, so it feels like it would be hard to require that those ignores have error codes)

[DetachHead]

@PeterJCLaw hmm, perhaps a separate option to prohibit file-level ignore comments?

[JelleZijlstra]

I would not worry about those. If you're using a file-level ignore, you probably want to ignore everything.

[KotlinIsland]

Kotlin handles per code file wide suppression
@file:Suppress("UNCHECKED_CAST"), and I agree.