FA100 doesn't catch using modern annotation syntax when target version is 3.9 #4553
Description
As I'm reading it, FA100 should add a from __future__ import annotations import when a file already uses modern annotation syntax and the configuration targets Python 3.9, but it doesn't:
Refs AUTOMATIC1111/stable-diffusion-webui#10580
$ cat a.py
def foo(x: str | None):
pass
$ ruff --version
ruff 0.0.269
$ ruff --target-version=py39 --select=FA100 --isolated a.py
$ ~/.pyenv/versions/3.9.16/bin/python3.9 a.py
Traceback (most recent call last):
File "a.py", line 1, in <module>
def foo(x: str | None):
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'