Description

abalkin

opened on Feb 19, 2020

Issue body actions

BPO	39680
Nosy	@abalkin, @pganssle

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/abalkin'
closed_at = None
created_at = <Date 2020-02-19.00:56:00.603>
labels = ['type-bug', '3.9']
title = 'datetime.astimezone() method does not handle invalid local times as required by PEP 495'
updated_at = <Date 2020-02-19.00:56:00.603>
user = 'https://github.com/abalkin'

bugs.python.org fields:

activity = <Date 2020-02-19.00:56:00.603>
actor = 'belopolsky'
assignee = 'belopolsky'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2020-02-19.00:56:00.603>
creator = 'belopolsky'
dependencies = []
files = []
hgrepos = []
issue_num = 39680
keywords = []
message_count = 1.0
messages = ['362241']
nosy_count = 2.0
nosy_names = ['belopolsky', 'p-ganssle']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39680'
versions = ['Python 3.9']

Linked PRs

• gh-83861: Fix datetime.astimezone() method #101545

Activity

1. abalkin commented on Feb 19, 2020

   

   abalkin

   on Feb 19, 2020

   MemberAuthor

   More actions

   Let g be an invalid time in a New York spring-forward gap:

   >>> g = datetime(2020, 3, 8, 2, 30)

   According to PEP-495, conversion of such instance to UTC should return a value that corresponds to a valid local time greater than g, but

   >>> print(g.astimezone(timezone.utc).astimezone())
   2020-03-08 01:30:00-05:00

   Also, conversion of the same instance with fold=1 to UTC and back should produce a lesser time, but

   >>> print(g.replace(fold=1).astimezone(timezone.utc).astimezone())
   2020-03-08 03:30:00-04:00

   Note that conversion to and from timestamp works correctly:

   >>> print(datetime.fromtimestamp(g.timestamp()))
   2020-03-08 03:30:00
   >>> print(datetime.fromtimestamp(g.replace(fold=1).timestamp()))
   2020-03-08 01:30:00
2. abalkin

   added

   3.9 (EOL)end of lifeend of life

   on Feb 19, 2020
3. abalkin

   self-assigned this

   on Feb 19, 2020
4. abalkin

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   3.9 (EOL)end of lifeend of life

   on Feb 19, 2020
5. abalkin

   self-assigned this

   on Feb 19, 2020
6. abalkin

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Feb 19, 2020
7. ezio-melotti

   transferred this issue fromon Apr 10, 2022
8. serhiy-storchaka

   added this to Date and time issues 🕰️on May 21, 2022
9. abalkin commented on Feb 2, 2023

   

   abalkin

   on Feb 2, 2023

   MemberAuthor

   More actions

   This bug is still present in the current master:

   Python 3.12.0a4+ (heads/main:0675b8f032, Feb  2 2023, 18:31:34) [Clang 14.0.0 (clang-1400.0.29.202)] on darwin
   Type "help", "copyright", "credits" or "license" for more information.
   >>> import time, os
   >>> from datetime import datetime, timezone
   >>> os.environ['TZ'] = 'America/New_York'
   >>> time.tzset()
   >>> time_in_gap = datetime(2020, 3, 8, 2, 30)
   >>> print(time_in_gap.astimezone(timezone.utc).astimezone())
   2020-03-08 01:30:00-05:00
   >>> print(time_in_gap.replace(fold=1).astimezone(timezone.utc).astimezone())
   2020-03-08 03:30:00-04:00

   Note that the same calculation done with explicit zone info gives correct results:

   >>> from zoneinfo import ZoneInfo
   >>> New_York = ZoneInfo('America/New_York')
   >>> time_in_gap = datetime(2020, 3, 8, 2, 30, tzinfo=New_York)
   >>> print(time_in_gap.astimezone(timezone.utc).astimezone(New_York))
   2020-03-08 03:30:00-04:00
   >>> print(time_in_gap.replace(fold=1).astimezone(timezone.utc).astimezone(New_York))
   2020-03-08 01:30:00-05:00
   

   (kudos to @pganssle!)
10. abalkin

    added 2 commits that reference this issue on Feb 3, 2023

    Fix datetime.astimezone() method (pythongh-83861)

    3b8235a

    Fix datetime.astimezone() method (pythongh-83861)

    d3b6683
11. miss-islington

    added a commit that references this issue on Apr 19, 2023

    gh-83861: Fix datetime.astimezone() method (GH-101545)

    2b1260c
12. carljm

    added a commit that references this issue on Apr 20, 2023

    Merge branch 'main' into superopt

    5c0a21c
13. iritkatriel

    added

    stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

    on Nov 28, 2023
14. encukou commented on Mar 10, 2025

    

    encukou

    on Mar 10, 2025

    Member

    More actions

    The PR was merged for 3.12, so I'll close.
15. encukou

    closed this as completedon Mar 10, 2025
16. github-project-automation

    moved this to Done in Date and time issues 🕰️on Mar 10, 2025

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