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gh-152212: Reject a POSIX TZ footer with a missing std offset in pure-Python zoneinfo #152213

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Merged
StanFromIreland merged 2 commits into from
Jun 27, 2026
Merged

gh-152212: Reject a POSIX TZ footer with a missing std offset in pure-Python zoneinfo #152213

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gh-152212: Reject a POSIX TZ footer with a missing std offset in pure…
tonghuaroot Jun 25, 2026
aec9aea
gh-152212: Add STD-offset-required comment and tighten NEWS per review
tonghuaroot Jun 27, 2026
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gh-152212: Add STD-offset-required comment and tighten NEWS per review
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@tonghuaroot
tonghuaroot committed Jun 27, 2026
commit aec9aea6c8a62f015044b1357385ee2bf0abff2e
1 change: 1 addition & 0 deletions Lib/zoneinfo/_zoneinfo.py
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Original file line number Diff line number Diff line change
Expand Up @@ -672,6 +672,7 @@ def _parse_tz_str(tz_str):
except ValueError as e:
raise ValueError(f"Invalid STD offset in {tz_str}") from e
else:
# The STD offset is required
raise ValueError(f"Invalid STD offset in {tz_str}")
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if dst_abbr is not None:
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9 changes: 3 additions & 6 deletions Misc/NEWS.d/next/Library/2026-06-25-12-00-00.gh-issue-152212.Zk7Qm2.rst
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@@ -1,6 +1,3 @@
Fixed a parity bug in the pure-Python :mod:`zoneinfo` implementation, which
accepted a POSIX TZ footer whose ``std`` field had no offset (for example
``AAA``), silently building a fixed offset-0 zone. Such a string is invalid per
POSIX (the offset following ``std`` is required), and the C accelerator already
rejects it; the pure-Python parser now raises :exc:`ValueError` to match.
Patch by tonghuaroot.
Fix the pure-Python :mod:`zoneinfo` parser accepting a POSIX TZ string with a
``std`` abbreviation but no offset. This is invalid per POSIX and now
raises :exc:`ValueError`, matching the C accelerator. Patch by tonghuaroot.
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