dateutil.parser.parse() giving different results for BST in Linux and Windows

[HughMacdonald]

I'm seeing some odd behaviour here between the Linux (on a Raspberry Pi) and Windows.

Firstly, dateutil._version.version gives me 2.9.0.post0 on both systems. Linux is running Python 3.11.2 and Windows is running Python 3.10.11.

I am in the UK, so local timezone is (as of this morning) BST, which is UTC+01:00. Both of the machines I'm running this on a

Here's my test code:

from dateutil import parser
t_str = '2024-03-31 02:00:25 BST+0100'
t = parser.parse(t_str)
print(t.tzinfo())
# Linux : tzlocal()
# Windows : tzoffset('BST', -3600)
print(t.timestamp())
# Linux : 1711846825.0
# Windows : 1711854025.0

So it appears that something on Windows is treating the BST+0100 as an hour offset the other way. (If I change the string to be BST-0100 it does it to +3600)

The string I'm getting here is coming from an external source, so I can't change the format of it.

If I import tzlocal and run tzlocal.get_localzone() on both machines, I get Europe/London on both

Any idea why this is happening? Am I doing something wrong, or is this a bug in the parser somewhere along the way?

[HughMacdonald]

I found that passing in tzinfos={"GMT": 0, "BST": 3600} fixed my issue. Without this, though, I'm not sure why it wasn't just ignoring the BST/GMT in the string and using the +0100 as the offset.