`datetime.strptime` is broken with timezones without DST

[vytas7]

It seems that some datetime.strptime expressions, especially including the timezone (%Z) break in GraalPy:

(graalenv) bash-5.2# python -V && python -c "import datetime; print(datetime.datetime.strptime('Tue, 15 Nov 1994 12:45:26 GMT', '%a, %d %b %Y %H:%M:%S %Z'))"
GraalPy 3.11.7 (GraalVM CE Native 24.2.2)
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/opt/graalpy-24.2.2/lib/python3.11/datetime.py", line 2059, in strptime
    return _strptime._strptime_datetime(cls, date_string, format)
  File "/opt/graalpy-24.2.2/lib/python3.11/_strptime.py", line 568, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
  File "/opt/graalpy-24.2.2/lib/python3.11/_strptime.py", line 480, in _strptime
    if (time.tzname[0] == time.tzname[1] and
IndexError: tuple index out of range

Cf vanilla CPython 3.11.7:

root@3133141ae9f2:/# python -V && python -c "import datetime; print(datetime.datetime.strptime('Tue, 15 Nov 1994 12:45:26 GMT', '%a, %d %b %Y %H:%M:%S %Z'))"
Python 3.11.7
1994-11-15 12:45:26

So it doesn't look like a standard library issue, but something else is going on 🤔

[msimacek]

Hi @vytas7, it seems that this bug can surface when your timezone doesn't have daylight savings time. I'll fix it shortly. As a workaround, you can try to set TZ to a timezone that does have daylight savings time.

[msimacek]

And thank you for the report. It seems that every machine we run tests on always had a timezone with DST so we didn't notice the bug.

[vytas7]

Thanks! This is not urgent, I was just looking whether falcon could support GraalPy.

While there were several other test failures, they represent subtle differences between the interpreters rather than anything real preventing the use of the framework. I haven't investigated though whether any application servers can run on Graal, but at least wsgiref.simple_server works.

[vytas7]

Thanks for fixing this bug @msimacek!
I'll look into Falcon supporting GraalPy once a new Graal release is out.

[msimacek]

Please note that the September 25.0 release was too far in the pipeline to get the fix. It should get into 25.0.1 in October