Compatibility with flake8 --extend-select

[JelleZijlstra]

It doesn't work:

% python -m flake8 --select=Y091 tests/raise.pyi
tests/raise.pyi:4:9: Y091 Function body must not contain "raise"
tests/raise.pyi:7:9: Y091 Function body must not contain "raise"
% python -m flake8 --extend-select=Y091 tests/raise.pyi
% 

[JelleZijlstra]

https://flake8.pycqa.org/en/latest/plugin-development/index.html doesn't say anything about creating codes that are disabled by default, so probably there still isn't a native way to do this. In working on #86 I noticed that it's really easy to disable everything else while trying to turn on a disabled-by-default check, so I think it's going to be a better way forward to get rid of the disabled-by-default checks.

[Akuli]

There's a comment that says the functionality is "Adapted from flake8-bugbear". We could look at how flake8-bugbear does this, and whether it has the same problems.

[JelleZijlstra]

Their code is still basically the same: https://github.com/PyCQA/flake8-bugbear/blob/master/bugbear.py#L131.

[Akuli]

Here's another idea: You typically want to use the most modern syntax that a specific Python version supports. For example, if you target 3.9+ you can use explicit type aliases, but if you target 3.8+ you can't. (Edit: I'm no longer sure if this makes sense. Doesn't typing_extensions backport basically everything?)

Maybe a better approach would be configuring the python version to target, instead of enabling individual disabled-by-default error codes? Or if that isn't possible, enable everything by default (as if you targeted the latest Python version), and ask users to silence warnings if they support something older too?

[JelleZijlstra]

Maybe a better approach would be configuring the python version to target

That doesn't make sense for stubs because stubs are mostly independent of Python version. TypeAlias for example should work in all Python versions in stubs (assuming you import it from typing_extensions); the problem is that pytype doesn't support it yet.