New submission from Huon Wilson <wilson.h...@gmail.com>:
The documentation suggests that two datetimes that represent the same moment should compare equal, even if they have different timezones: "If both comparands are aware and have different tzinfo attributes, the comparands are first adjusted by subtracting their UTC offsets (obtained from self.utcoffset())." (below https://docs.python.org/3/library/datetime.html#datetime.datetime.fold) This doesn't seem to be true for == with ZoneInfo timezones, even though it is true for <= and >=, and -, meaning these seem to violate mathematical laws/expectations: from zoneinfo import ZoneInfo from datetime import datetime, timezone dt_utc = datetime(2020, 11, 1, 8, tzinfo=timezone.utc) dt_local = dt_utc.astimezone(ZoneInfo("America/Los_Angeles")) print(f"{dt_local == dt_utc = }") print(f"{dt_local <= dt_utc = }") print(f"{dt_local >= dt_utc = }") print(f"{dt_local - dt_utc = }") Output: dt_local == dt_utc = False dt_local <= dt_utc = True dt_local >= dt_utc = True dt_local - dt_utc = datetime.timedelta(0) Tested with: - macOS 11.4; Python 3.9.7, 3.10.1, 3.11.0a3 - Linux; via docker image python:3.9.7 Full test including comparisons to python-dateutil (same behaviour as ZoneInfo) and pytz (== gives True as expected) is attached. Comparing timestamps for exact equality is potentially unusual, but we use it extensively in tests for some time-handling functions. ---------- components: Library (Lib) files: tz.py messages: 409113 nosy: huonw priority: normal severity: normal status: open title: Same-moment datetimes with different ZoneInfo timezones are not considered == type: behavior versions: Python 3.10, Python 3.11, Python 3.9 Added file: https://bugs.python.org/file50516/tz.py _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue46169> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
