[Python 3.9 compat] Check for __class_getitem__ #3951
Description
Python 3.9 starts to make a great use of __class_getitem__ for exemple in collections.deque.
pylint/checkers/typecheck.py should probably look for it to infer if something is subscriptable.
Reproducer:
import collections
print(collections.deque[int])which give:
test.py:11:6: E1136: Value 'collections.deque' is unsubscriptable (unsubscriptable-object)
while the code works thanks to the __class_getitem__.