Wrong F401 error raised

[ocelotl]

This seems like a regression of #247. The example below uses nox.

I created a directory with three files:

module_a.py  module_b.py  noxfile.py

module_a.py:

class ClassA:
    pass

module_b.py:

from module_a import ClassA


for _ in range(4):  # type: ClassA
    print(0)

noxfile.py:

from nox import session


@session(python=["3.10"])
def lint(session):
    session.install("flake8==5.0.4")
    # session.install("flake8==6.0.0")
    session.run("flake8", "--version")
    session.run("flake8")

When I run nox, no issues are raised:

nox > Running session lint-3.10
nox > Creating virtual environment (virtualenv) using python3.10 in .nox/lint-3-10
nox > python -m pip install flake8==5.0.4
nox > flake8 --version
5.0.4 (mccabe: 0.7.0, pycodestyle: 2.9.1, pyflakes: 2.5.0) CPython 3.10.4 on Linux
nox > flake8 
nox > Session lint-3.10 was successful.

When I uncomment # session.install("flake8==6.0.0"), comment session.install("flake8==5.0.4") and run nox again, an issue is raised:

nox > Running session lint-3.10
nox > Creating virtual environment (virtualenv) using python3.10 in .nox/lint-3-10
nox > python -m pip install flake8==6.0.0
nox > flake8 --version
6.0.0 (mccabe: 0.7.0, pycodestyle: 2.10.0, pyflakes: 3.0.1) CPython 3.10.4 on Linux
nox > flake8 
./module_b.py:1:1: F401 'module_a.ClassA' imported but unused
nox > Command flake8  failed with exit code 1
nox > Session lint-3.10 failed.

[asottile]

@ocelotl please (1) search the issue tracker and (2) read the changelog for 3.0.0

[ikapelyukhin]

 3.0.0 (2022-11-23)

    [...]
    Remove handling of python 2.x # type: comments. Use annotations instead

[rchl]

Was this change made knowing full well that it's only possible to use annotations for variables from python 3.6 and up?

I'm asking since the commit message (Remove handling of python 2.x # type: comments) doesn't make it clear that this was intentional.

[asottile]

pyflakes only supports python3.6 and above