Subclasses of mailbox.Mailbox not recognized as such #14935
Description
Consider the following code:
from abc import ABC, abstractmethod import mailbox class MailboxFactory(ABC): @abstractmethod def open(self) -> mailbox.Mailbox: ... class MboxFactory(MailboxFactory): def __init__(self, path: str) -> None: self.path = path def open(self) -> mailbox.mbox: return mailbox.mbox(self.path)I'm 90% sure this should be acceptable, but running 1.18.2 on this code produces the error:
mailbox02.py:14: error: Return type "mbox" of "open" incompatible with return type "Mailbox[Message[str, str]]" in supertype "MailboxFactory" [override] Found 1 error in 1 file (checked 1 source file) Similar errors happen for other Mailbox subclasses as well.