extend-select argument not working with arithmetic operator whitespace E226

[gregorybchris]

Flake8 installation

$ pip install flake8

Bug report JSON:

{
  "dependencies": [],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.8.12",
    "system": "Darwin"
  },
  "plugins": [
    {
      "is_local": false,
      "plugin": "mccabe",
      "version": "0.6.1"
    },
    {
      "is_local": false,
      "plugin": "pycodestyle",
      "version": "2.8.0"
    },
    {
      "is_local": false,
      "plugin": "pyflakes",
      "version": "2.4.0"
    }
  ],
  "version": "4.0.1"
}

My initial expectation is that flake8 should error when binary arithmetic operators are not surrounded by whitespace (E226). My further expectation is that if E226 is not enabled by default I should be able to enable it as an additional check. It seems like there might be a bug breaking E226 validation and potentially extend-select as well.

My project uses a setup.cfg configure flake8. For that reason I would like to use extend-select to avoid calling flake8 in the command line twice. The following example reproduces the issue:

Input file a.py:

a = 4-1

# E226 is not found in a.py
$ flake8 a.py
<no output>

# explicitly selecting E226 has the desired output, but will not catch other errors (by design)
$ flake8 a.py --select E226
a.py:1:6: E226 missing whitespace around arithmetic operator

# extend-select does not work as expected to catching default errors and E226
$ flake8 a.py --extend-select E226
<no output>

# ignoring all warnings somehow circumvents the issue and allows E226 to be caught
$ flake8 a.py --ignore W
a.py:1:6: E226 missing whitespace around arithmetic operator

# ignoring random text works the same way
$ flake8 a.py --ignore 0
a.py:1:6: E226 missing whitespace around arithmetic operator

[asottile]

E226 is ignored by default:

flake8/src/flake8/defaults.py

Line 16 in e944e09

IGNORE = ("E121", "E123", "E126", "E226", "E24", "E704", "W503", "W504")

[gregorybchris]

@asottile Should I be able to enable it with --extend-select? And any idea why ignoring random text would cause that check to be enabled?

Will you please provide a solution to enable E226 checking while retaining all default validations?

[asottile]

I agree it seems odd, but it appears to be intentional given #1312

And any idea why ignoring random text would cause that check to be enabled?

setting --ignore overrides the ignore list, so it removes E226 from the default ignore

[gregorybchris]

setting --ignore overrides the ignore list

This makes sense. So --ignore 0 is not a good option because it has the side effect of overriding all default ignores.

it appears to be intentional given #1312

I'm not sure what part of #1312 indicates that --extend-select should not be usable for validations that are ignored by default. But would you agree that --extend-select should be usable for validations that are ignored by default @asottile?

[asottile]

I don't think --select or --extend-select are really meant to be "override what's in --ignore", or at least there's an ambiguity when they are both selected and ignored.

I think the minimal setting to do what you want is to override the default ignore list without E226, so --ignore=E121,E123,E126,E24,E704,W503,W504

[gregorybchris]

I guess that's a pretty good workaround considering the list of default ignores is so short. Thanks.

I don't think --select or --extend-select are really meant to be "override what's in --ignore"

Because I do imagine others might encounter the same problem, I'll try my best to make the case one more time. Two use cases for --extend-select:

1. Select something that has been ignored explicitly on a less granular level.
   --ignore E --extend-select E225
2. Select something ignored by default
   --extend-select E226

Argument 1: I do not expect whether a rule is default selected/ignored to affect whether --extend-select works. If I as the user specify that I want E226 validated (and I do not specify any conflicting settings), I see no reason why the default setting should interact with my choices.

Argument 2: Ignore and select are opposites. If I --extend-ignore something that is default selected there is not a problem ignoring it. Swapping ignore and select should not have different behavior.

Argument 3: The fact that the workaround is to re-ignore every other default ignore indicates to me that there's an issue here. The intuition behind --extend-select in the first place is to avoid long lists of ignores/selects.

[asottile]

note that --extend-select E226 is somewhat nonsense because there's already --select E by default which includes E226

I'm also not here to argue, but your arguments don't really work given that