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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"datetime library doesn't support valid ISO-8601 alternative for midnight","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\nAccording to [ISO-8601](https://en.wikipedia.org/wiki/ISO_8601), a time of `24:00` on a given date is a valid alternative to `00:00` of the following date, however Python does not support this, raising the following error when attempted: `ValueError: hour must be in 0..23`.\r\n\r\nThis bug can be seen from multiple scenarios, specifically anything that internally calls the [`_check_time_fields` function](https://github.com/python/cpython/blob/main/Lib/datetime.py#L531-L546), such as the following:\r\n```python\r\n\u003e\u003e\u003e import datetime\r\n\u003e\u003e\u003e datetime.datetime(2022, 1, 2, 24, 0, 0)  # should be equivalent to 2022-01-03 00:00:00\r\nTraceback (most recent call last):\r\n  File \"\u003cpyshell#2\u003e\", line 1, in \u003cmodule\u003e\r\n    datetime.datetime(2022, 3, 4, 24, 0, 0)\r\nValueError: hour must be in 0..23\r\n```\r\nThe fix for this is relatively simple: have an explicit check within [`_check_time_fields`](https://github.com/python/cpython/blob/main/Lib/datetime.py#L531-L546) for the scenario where `hour == 24 and minute == 0 and second == 0 and microsecond == 0`, or more concisely `hour == 24 and not any((minute, second, microsecond))`, and in this scenario increase the day by one (adjusting the week/month/year as necessary) and set the hour to 0.\r\n\r\nI imagine the [`check_time_args` C function](https://github.com/python/cpython/blob/main/Modules/_datetimemodule.c#L467-L499) would also have to be updated.\r\n\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: 3.9.12, 3.10.7, 3.11.2 (presumably applies to all)\r\n- Operating system and architecture: MacOS Ventura arm64 (presumably applies to all)\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-105856\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/TizzySaurus","@type":"Person","name":"TizzySaurus"},"datePublished":"2023-03-05T20:45:11.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":19},"url":"https://github.com/102450/cpython/issues/102450"}