René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Suspected `PyErr_Fetch()` behavior change","articleBody":"\u003c!--\r\n  If you're new to Python and you're not sure whether what you're experiencing is a bug, the CPython issue tracker is not\r\n  the right place to seek help. Consider the following options instead:\r\n\r\n  - reading the Python tutorial: https://docs.python.org/3/tutorial/\r\n  - posting in the \"Users\" category on discuss.python.org: https://discuss.python.org/c/users/7\r\n  - emailing the Python-list mailing list: https://mail.python.org/mailman/listinfo/python-list\r\n  - searching our issue tracker (https://github.com/python/cpython/issues) to see if\r\n    your problem has already been reported\r\n--\u003e\r\n\r\n# Bug report\r\n\r\nWhile testing pybind11 with Python 3.12alpha6 I ran into what looks like a `PyErr_Fetch()` behavior change. I also tried with the main branch @ c6858d1e7f4cd3184d5ddea4025ad5dfc7596546.\r\n\r\nI think the issue reduces to:\r\n\r\n* `PyErr_SetObject()` as e.g. here: https://github.com/pybind/pybind11/blob/442261da585536521ff459b1457b2904895f23b4/tests/test_exceptions.cpp#L309\r\n\r\n* Followed more-or-less immediately by a `PyErr_Fetch()` as e.g. here: https://github.com/pybind/pybind11/blob/442261da585536521ff459b1457b2904895f23b4/include/pybind11/pytypes.h#L482\r\n\r\nThe special twist is that the exception type involved raises a `ValueError` in its `__init__`:\r\n\r\n* https://github.com/pybind/pybind11/blob/442261da585536521ff459b1457b2904895f23b4/tests/test_exceptions.py#L295\r\n\r\nFor easy reference the same code copy-pasted here:\r\n\r\n```\r\nclass FlakyException(Exception):\r\n    def __init__(self, failure_point):\r\n        if failure_point == \"failure_point_init\":\r\n            raise ValueError(\"triggered_failure_point_init\")\r\n        self.failure_point = failure_point\r\n```\r\n\r\n* Up to and including 3.12alpha3: `PyErr_Fetch()` produces the `FlakyException` type ([this here](https://github.com/pybind/pybind11/blob/442261da585536521ff459b1457b2904895f23b4/include/pybind11/pytypes.h#L488)).\r\n\r\n* **With 3.12alpha6: `PyErr_Fetch()` produces the `ValueError` type** instead.\r\n\r\nAdditional detail:\r\n\r\nUp to and including 3.12alpha3: only `PyErr_NormalizeException()` hits the `ValueError` in `FlakyException._init__`, but not `PyErr_Fetch()`.\r\n\r\n# Your environment\r\n\r\n\u003c!-- Include as many relevant details as possible about the environment you experienced the bug in --\u003e\r\n\r\n- CPython versions tested on: 3.12alpha6,  main branch @ c6858d1e7f4cd3184d5ddea4025ad5dfc7596546\r\n- Operating system and architecture: Debian 5.19.11 clang14, ubuntu22 gcc11\r\n\r\n\u003c!--\r\nYou can freely edit this text. Remove any lines you believe are unnecessary.\r\n--\u003e\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-102606\n* gh-102607\n* gh-102675\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/rwgk","@type":"Person","name":"rwgk"},"datePublished":"2023-03-11T06:09:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":22},"url":"https://github.com/102594/cpython/issues/102594"}