python-dateutil 3.0.0

on Python PyPI

This is the last major version of dateutil that will support any version of Python older than 3.11. The next release will be the 4.x series, which will support Python 3.11 and later. We may release fixes for serious bugs in the 3.0.x series, but there are no plans for new features there.

The biggest change in this release is a rewrite of tz.tzfile, which affects nearly every user of dateutil.tz and changes the UTC offset of nonexistent times (see below). dateutil also now depends on the tzdata package, and no longer ships its own time zone database.

Data updates

• dateutil no longer bundles a copy of the IANA time zone database. Time zone data now comes from the system (see dateutil.tz.TZPATH) or, failing that, from the new tzdata dependency, so the data version is whatever version of tzdata is installed. (gh pr #1130)

Features

• Rewrote tz.tzfile based on a backport of the zoneinfo module's pure-Python implementation. This adds support for Version 2 and Version 3 tzfile(5) binaries, resolving issues with timestamps beyond 2038 and "slim" format binaries. (gh issues #462, #1059, gh pr #1130)
• Added dateutil.tz.TZPATH and dateutil.tz.reset_tzpath to allow for runtime configuration of the IANA time zone data search path. These replace the mutable dateutil.tz.TZPATHS list, which has been removed. (gh pr #1130)
• dateutil now depends on the tzdata package, which gettz consults after the search path and before the Windows registry. On Windows this means that names that are both IANA keys and Windows time zone names, such as "UTC", now return a tzfile rather than a tzwin. (gh pr #1130)

Bugfixes

• tz.tzfile now follows PEP 495 for times that fall in a gap: with fold=0 it uses the offset from before the transition, and with fold=1 the offset from after it. Previously it always used the offset from after the transition, so for example datetime(2003, 4, 6, 2, 30, tzinfo=tz.gettz("America/New_York")) had a UTC offset of -04:00, where it now has -05:00, the same as with zoneinfo. (gh pr #1130)
• tz.tzfile objects for fixed-offset zones, such as tz.gettz("UTC"), now return their offset, DST offset and abbreviation when utcoffset, dst and tzname are called with None, as tz.tzutc, tz.tzoffset and zoneinfo.ZoneInfo do. This means that datetime.time objects with such a zone attached are now aware: time(12, tzinfo=tz.gettz("UTC")).isoformat() is now "12:00:00+00:00" rather than "12:00:00". (gh pr #1130)
• tz.tzfile now infers dst() from the standard time on both sides of each DST period, rather than only the one before it, and does so for each transition rather than for each local time type. This fixes dst() for double summer time (e.g. in Europe/London in the 1940s), for half-hour DST (e.g. in Pacific/Rarotonga) and where the standard offset changed at the same time as a DST transition (e.g. in America/Bahia_Banderas in 2010). Against the standard offsets in the tz database source, the only remaining errors are in Europe/Paris in 1944 and 1945. (gh pr #1130)
• Fixed rrulestr raising ValueError on experimental X- parameters in an RRULE line (such as GNOME Evolution's X-EVOLUTION-ENDDATE); these are now ignored as RFC 5545 permits. Fixed by @yajo (gh pr #1374)
• Enabled pickling and deepcopy of cached rrule and rruleset instances. The cache setting is preserved, and cached results are regenerated on demand without copying locks or generators. Reported by @niccokunzmann (gh issue #1369). Fixed by @Jay1023CN (gh pr #1600).
• Fixed relativedelta.__ne__ raising TypeError when comparing against an unsupported type such as None; it now returns True. Reported and fixed by @kevinkt1 (gh issue #1157, gh pr #1158)
• Raised the minimum version of six to 1.6, fixing No module named 'six.moves' errors with older versions. Reported by @skytreader (gh issue #1415), fixed by @jdarias3 (gh pr #1424).

Deprecations

• Deprecated the dateutil.zoneinfo module. The module now acts as a wrapper around the tzdata package and will be removed in a future version. Users are encouraged to migrate to dateutil.tz.gettz or the standard library's zoneinfo module. dateutil.zoneinfo.rebuild.rebuild no longer does anything, and by default raises RebuildDeprecationWarning as an error; filter the warning to call it as a no-op. (gh pr #1130)
• Deprecated passing gettz a relative key that refers to a file outside of every directory on TZPATH, such as "../../etc/localtime". By default this now raises dateutil.tz.DeprecatedTzKeyWarning as an error; filter the warning to keep the old behavior for now, or pass an absolute path instead. (gh pr #1130)

Documentation changes

• Added intersphinx to the docs build and cleaned up some broken links. (gh pr #1463)

Misc

• Releases are now uploaded to PyPI using trusted publishing, and the built sdist and wheel are tested on all supported platforms before upload. (gh pr #1619, #1622)
• Changes to CI, tests and release tooling that do not affect users of the package: gh pr #1417, #1462, #1464, #1465, #1466, #1467, #1468, #1469, #1470, #1499, #1501, #1504, #1576, #1577, #1578, #1581, #1585.