Cryptography ECB is reported to be abstract

[sk-]

Describe the Bug

Pyrefly reports that cryptography.hazmat.primitives.ciphers.modes.ECB is abstract, because of how the method is defined.

from cryptography.hazmat.primitives.ciphers import modes

print(modes.ECB())

import abc


class Mode(metaclass=abc.ABCMeta):
    @property
    @abc.abstractmethod
    def name(self) -> str:
        """
        A string naming this mode (e.g. "ECB", "CBC").
        """

    @abc.abstractmethod
    def validate_for_algorithm(self, algorithm: str) -> None:
        """
        Checks that all the necessary invariants of this (mode, algorithm)
        combination are met.
        """


def _check_aes_key_length(self: Mode, algorithm: str) -> None:
    pass


class ECB(Mode):
    name = "ECB"

    validate_for_algorithm = _check_aes_key_length


print(ECB())

In both cases, the code executes correctly, but pyrefly reports

ERROR Cannot instantiate `ECB` because the following members are abstract: `validate_for_algorithm` [bad-instantiation]
 --> pyrefly_cryptography.py:3:16
  |
3 | print(modes.ECB())
  |                ^^
  |
 INFO 1 error

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSIEAtsbgE4AuABKtgMZMA663bUqcOEwCyuTDAAUVGA1R8BcALys2hAIIAhAMLCZqAJSJuTE0wACxOrmIxGpY6bMrCrOAzpyG0hgAsxDk3EwJnRUaQk4GCgwfSYAWgA%2BJjc6I3RTDK4QTmzs9MyTNWT3CHQAcxCw0orfCCEqMRgmCRhCMsIsgFEtDRyAGiyerRz9QgDMnMm88ad2F2wUz28-THGgpgA3VCgITFQGGAB9MHpD7bL6CF8qCKiwAfPL68RiuljEpgA5XHQYNIKTFNJvkClofDA2ABrIS%2BfYsKBQJi%2BJq-NjwNB0UhMUpbOgQDAMIS4YK1IRSRoPKAXPHXfTjDJsXBUbClfYQH4sOhNbxjEETXLA7jrQ5scFQs7wQ6QmCkQ6wcq%2BW7RF6icSU6lXHxUF4pd5Jb6-f6mYgKbhm9DyQRMboaCSqmCGcahaRMRRdHqCvlbHZ7A7HU6PGla11MEViyESuBSmVymAKnzmyylBgSG0SfT6EB9EAAVwY0DgJHIiBAAGImABVfM7BhYsA5i35n5wc3rE50Kj7Q7oHPM2wSfAvZN615Gkxchg5ujpMA5T697C2F7AfAAX2BWZAZC5YCgpEIDCZUAo5YACqQd3vkhgcAQmIz0JAylO2T9eeWAMowJo%2BBgMYhwIgAD0QHbjAu77vQZRAXGQGYLgbBwEBD5Pi%2BTboEBTDtiwWzQKwsD3j8qEeOhTDWOhhbcGQvg-HEGy2HA7LpG6OQAMyEAAjAATBuq7Zp4ED0QAYtAMAUGgWB4EQZAgKuQA

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