Enforce error codes on type: ignores

[TylerYep]

Feature

As far as I know, there's no way to enforce an error code is added to the end of a type ignore. Since error codes can narrow the type errors ignored on a specific line, it would be useful to ensure all # type: ignores in a codebase included an error code, to avoid silencing additional errors or disabling otherwise valid typechecking on a line.

The feature could be a config option --enforce-error-codes that verifies all type: ignores specify an error code.

x: int = None  # type: ignore                <- mypy complains
x: int = None  # type: ignore[assignment]    <- good!

[AlexWaygood]

Implemented in #10712 (EDIT: linked the wrong PR accidentally, should have linked #11633)

[TylerYep]

I don't think you linked a PR that adds this command line argument. Could you double check? Reopening.

[JelleZijlstra]

It's #11633

[AlexWaygood]

Whoops, my bad. Thanks @JelleZijlstra!

[TylerYep]

Ah, thanks!

Update: Realized it's enable_error_code = ignore-without-code