file-level noqa should raise an error if specific errors are provided (to avoid confusion)

how did you install flake8?

pip install flake8

unmodified output of flake8 --bug-report

{
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.10.7",
    "system": "Linux"
  },
  "plugins": [
    {
      "plugin": "mccabe",
      "version": "0.7.0"
    },
    {
      "plugin": "pycodestyle",
      "version": "2.10.0"
    },
    {
      "plugin": "pyflakes",
      "version": "3.0.1"
    }
  ],
  "version": "6.0.0"
}

describe the problem

what I expected to happen

I'm seeing developers using the file-level-noqa ignore wrongly from time to time, providing specific errors like # flake8: noqa: E712. What's confusing is that it gives the impression that it works as it doesn't throw that error anymore but the developers' understanding is incorrect (all errors are ignore). I understood that you don't want to support the file-level-specific-ignores but I think flake8 should do something to prevent this confusion.

See for instance https://til.codeinthehole.com/posts/filelevel-flake8-comments-ignore-all-errors/

My suggestion would be to detect that and throw an error? Somehow it is like providing a flake8 config with a wrong format

sample code

# flake8: noqa: E712

from os import *       # F401
assert True == True # E712

Let me know what you think, happy to work on this if you would welcome a PR

Start by locating where Flake8 parses file-level # flake8: noqa comments and where related configuration errors are tested. Reproduce the sample using flake8, then add coverage for a file-level noqa with a specific error code; done means that misuse produces a clear error instead of silently ignoring all errors.