Fix local timezone offsets in get_timezone_name(None)

babel/dates.py

@@ -87,8 +87,8 @@ def _get_dt_and_tzinfo(
     :rtype: tuple[datetime, tzinfo]
     """
     if dt_or_tzinfo is None:
-        dt = datetime.datetime.now()
         tzinfo = LOCALTZ
+        dt = datetime.datetime.now(tzinfo)
     elif isinstance(dt_or_tzinfo, str):
         dt = None
         tzinfo = get_timezone(dt_or_tzinfo)
@@ -626,7 +626,7 @@ def get_timezone_name(
                          the timezone; if a ``tzinfo`` object is used, the
                          resulting display name will be generic, i.e.
                          independent of daylight savings time; if `None`, the
-                         current date in UTC is assumed
+                         current date and time in the local timezone is assumed
     :param width: either "long" or "short"
     :param uncommon: deprecated and ignored
     :param zone_variant: defines the zone variation to return.  By default the
@@ -648,7 +648,7 @@ def get_timezone_name(
         if dt is None:
             zone_variant = 'generic'
         else:
-            dst = tzinfo.dst(dt)
+            dst = dt.dst()
             zone_variant = "daylight" if dst else "standard"
     else:
         if zone_variant not in ('generic', 'standard', 'daylight'):

tests/test_dates.py

@@ -11,7 +11,7 @@
 # history and logs, available at https://github.com/python-babel/babel/commits/master/.
 
 import calendar
-from datetime import date, datetime, time, timedelta
+from datetime import date, datetime, time, timedelta, timezone
 
 import freezegun
 import pytest
@@ -361,6 +361,43 @@ def test_get_timezone_name_misc(timezone_getter):
     assert (dates.get_timezone_name(time(16, 20), locale='en_US', width='short') == "UTC")
 
 
+@pytest.mark.parametrize(
+    ('offset', 'expected'),
+    [
+        (timedelta(hours=5, minutes=30), 'GMT+05:30'),
+        (-timedelta(hours=3, minutes=30), 'GMT-03:30'),
+    ],
+)
+def test_get_timezone_name_none_uses_local_offset(monkeypatch, offset, expected):
+    monkeypatch.setattr(dates, 'LOCALTZ', timezone(offset))
+
+    with freezegun.freeze_time('2023-07-01 12:00:00'):
+        assert dates.get_timezone_name(None, locale='en') == expected
+
+
+@pytest.mark.parametrize(
+    ('frozen_time', 'expected_offset'),
+    [
+        ('2023-01-15 12:00:00', timedelta(hours=-5)),
+        ('2023-07-15 12:00:00', timedelta(hours=-4)),
+    ],
+)
+def test_get_dt_and_tzinfo_none_preserves_local_dst(
+    timezone_getter,
+    monkeypatch,
+    frozen_time,
+    expected_offset,
+):
+    local_tz = timezone_getter('America/New_York')
+    monkeypatch.setattr(dates, 'LOCALTZ', local_tz)
+
+    with freezegun.freeze_time(frozen_time):
+        dt, tzinfo = dates._get_dt_and_tzinfo(None)
+
+    assert tzinfo is local_tz
+    assert dt.utcoffset() == expected_offset
+
+
 def test_format_date():
     d = date(2007, 4, 1)
     assert dates.format_date(d, locale='en_US') == 'Apr 1, 2007'