Cannot determine type of "userlist"

Bug Report

Unexpected error Cannot determine type of "userlist". Needs a cyclic import to happen.

To Reproduce

foo.py

import bar

class Foo:
    def __init__(self) -> None:
        self.view_selector = object()

bar.py

from foo import Foo

class ServerView:
    def __init__(self) -> None:
        print(ChannelView().userlist)
        self.view_id = str(Foo().view_selector)

class ChannelView:
    def __init__(self) -> None:
        print(ServerView().view_id)
        self.userlist = object()

Expected Behavior

no error, or an error that does not confusingly go away when I delete a seemingly unrelated line of code

Actual Behavior

$ python3 -m mypy foo.py bar.py
bar.py:5: error: Cannot determine type of "userlist"
Found 1 error in 1 file (checked 2 source files)

Your Environment

• Mypy version used: master (053a1beb94ee4e5b3260725594315d1b6776e42f)
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: doesn't matter, why do you ask?
• Operating system and version: is a weird question to ask. I am tired of answering this question. But I guess it could be useful in some other issue.

Commencez par exécuter python3 -m mypy foo.py bar.py sur l’exemple fourni d’importations cycliques et comparez l’erreur userlist avec le comportement attendu. Suivez la manière dont mypy analyse les définitions de Foo, ServerView et ChannelView dans foo.py et bar.py ; le travail est terminé lorsque l’exemple ne produit plus l’erreur déroutante Cannot determine type of "userlist" ou signale un diagnostic plus clair.