python-dateutil: respect inheritance on relativedelta.__rsub__ (#11462) (#11463)

Author: MaicoTimmerman

stubs/python-dateutil/@tests/test_cases/check_inheritance.py

@@ -0,0 +1,22 @@
+from datetime import date, datetime
+from typing_extensions import assert_type
+
+from dateutil.relativedelta import relativedelta
+
+
+class MyDateTime(datetime):
+    pass
+
+
+d = MyDateTime.now()
+x = d - relativedelta(days=1)
+# https://github.com/python/typeshed/pull/11463
+# assert_type(x, MyDateTime)
+
+d3 = datetime.today()
+x3 = d3 - relativedelta(days=1)
+assert_type(x3, datetime)
+
+d2 = date.today()
+x2 = d2 - relativedelta(days=1)
+assert_type(x2, date)

stubs/python-dateutil/dateutil/relativedelta.pyi

@@ -1,11 +1,11 @@
-from datetime import date, datetime, timedelta
+from datetime import date, timedelta
 from typing import SupportsFloat, TypeVar, overload
 from typing_extensions import Self, TypeAlias
 
 # See #9817 for why we reexport this here
 from ._common import weekday as weekday
 
-_DateT = TypeVar("_DateT", date, datetime)
+_DateT = TypeVar("_DateT", bound=date)
 # Work around attribute and type having the same name.
 _Weekday: TypeAlias = weekday