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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"typing._allow_reckless_class_checks doesn't work when _abc doesn't exist.","articleBody":"# Bug report\n\n### Bug description:\n\n~When `typing._caller`'s `sys._getframe` fallback is triggered without `_abc` module, `_typing._allow_reckless_class_checks` fails to check `_py_abc` while running  `abc.ABCMeta.__instancecheck__`.~\n\nWithout `_abc` module, `_typing._allow_reckless_class_checks`fails to check `_py_abc`\n\nRelated code in typing.py:\nhttps://github.com/python/cpython/blob/v3.14.0b3/Lib/typing.py#L1846-L1863\n\nThis is technically a bug of typing.py, but really hard to be triggered on CPython.\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nmacOS\n\n# Solution suggestion\n\n## Patch typing._allow_reckless_class_checks to also check `_py_abc`\n~This is the most conservative approach. Compatible with all of previous scenarios and additionally fixing the bug.~\n\n## ~Patch typing._caller to remove sys._getframe or raise warning when fallback~\n~If the the `typing` requires to work with sys._getframemodulename, then let the users to know it has a caveat.~\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-136115\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/youknowone","@type":"Person","name":"youknowone"},"datePublished":"2025-06-27T16:00:41.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/136047/cpython/issues/136047"}