Segfault from `zoneinfo` with custom DateTime class

Crash report

What happened?

Here's a minimal reproducer

import zoneinfo
from datetime import date


class MyDateTime:
    def __init__(
        self,
        year: int,
        month: int,
        day: int,
        hour: int = 0,
        minute: int = 0,
        second: int = 0,
    ) -> None:
        self.ordinal = date(year, month, day).toordinal()
        self.hour = hour
        self.minute = minute
        self.second = second

    def toordinal(self) -> int:
        return self.ordinal


def whoopsie():
    tz_berlin = zoneinfo.ZoneInfo("Europe/Berlin")
    dt = MyDateTime(1995, 9, 2, 14, 34, 56)
    print(tz_berlin.utcoffset(dt), flush=True)

If I run whoopsie, I get one of the following outcomes:

• It prints 02:00:00
• It prints 01:00:00
• It prints 00:53:28
• It segfaults

<project dir>/venv313/bin/python -X dev <project dir>/segfault.py 
Fatal Python error: Segmentation fault

Current thread 0x00007fd62be47b80 (most recent call first):
 File "<project dir>/segfault.py", line 27 in whoopsie
 File "<project dir>/segfault.py", line 34 in <module>

I've tried running the test in a loop and it seems to always spit out the same result within a single run. So I assume some global state, memory layout, or or such is involved.

CPython versions tested on:

3.9, 3.13

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.0 (main, Oct 10 2024, 13:32:18) [GCC 11.4.0]

Linked PRs

• gh-125345
• gh-125824
• gh-139132

Commencez par le reproducer minimal dans le corps de l’issue et exécutez-le avec les versions de CPython indiquées afin de confirmer le crash et les offsets incohérents. Lisez ensuite les PR liés gh-125345, gh-125824 et gh-139132 ; le travail est terminé lorsque le reproducer ne provoque plus de segmentation fault et produit un résultat stable et correct.