Bug report

Bug description:

_get_protocol_attrs and _proto_hook in Lib/typing.py unconditionally swallow failures from base.__annotations__ access like this:

try:
    annotations = base.__annotations__
except Exception:
    annotations = annotationlib.get_annotations(...)

import typing

class BrokenMeta(type):
    def __getattribute__(cls, name):
        if name == '__annotations__':
            raise RuntimeError('simulated unrelated bug')
        return super().__getattribute__(name)

class Base(metaclass=BrokenMeta):
    pass

print(typing._get_protocol_attrs(Base))

set()

This looks intended to only handle AttributeError (no annotations) or NameError (undefined name during deferred evaluation), but except Exception is far too broad and also swallows genuine, unrelated bugs. _proto_hook reproduces the same way through issubclass().

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-155925: Narrow except Exception in typing Protocol helpers #155930