BUG: #29049 make holiday support offsets of offsets

doc/source/whatsnew/v3.0.0.rst

@@ -296,6 +296,7 @@ Performance improvements
 
 Bug fixes
 ~~~~~~~~~
+- Fixed bug in :class:`Series.Holiday` that leads to a ``TypeError`` when using ``Holiday.dates`` with a ``Holiday`` that is initialized with ``offset`` of type ``list`` which itself references another Holiday's list of offsets. (:issue:`29049`)
 - Fixed bug in :class:`SparseDtype` for equal comparison with na fill value. (:issue:`54770`)
 - Fixed bug in :meth:`DataFrame.join` inconsistently setting result index name (:issue:`55815`)
 - Fixed bug in :meth:`DataFrame.to_string` that raised ``StopIteration`` with nested DataFrames. (:issue:`16098`)

pandas/tests/tseries/holiday/test_holiday.py

@@ -6,6 +6,7 @@
 from pandas import (
     DatetimeIndex,
     Series,
+    to_datetime,
 )
 import pandas._testing as tm
 
@@ -198,6 +199,33 @@ def test_holidays_within_dates(holiday, start, expected):
     ) == [utc.localize(dt) for dt in expected]
 
 
+def test_holidays_within_dates_offset_of_offset():
+    # see gh-29049
+    # Test that the offset of an offset is correctly applied to the holiday
+    # And that dates can be calculated
+    holiday1 = Holiday(
+        "Holiday1",
+        month=USThanksgivingDay.month,
+        day=USThanksgivingDay.day,
+        offset=[USThanksgivingDay.offset, DateOffset(1)],
+    )
+    holiday2 = Holiday(
+        "Holiday2",
+        month=holiday1.month,
+        day=holiday1.day,
+        offset=[holiday1.offset, DateOffset(3)],
+    )
+    # there shall be no lists of lists here
+    for offset in holiday2.offset:
+        assert isinstance(offset, DateOffset)
+
+    min_date, max_date = (to_datetime(x) for x in ["2017-11-1", "2018-11-30"])
+    expected_min, expected_max = DatetimeIndex(["2017-11-27", "2018-11-26"])
+    actual_min, actual_max = holiday2.dates(min_date, max_date)
+    assert actual_min == expected_min
+    assert actual_max == expected_max
+
+
 @pytest.mark.parametrize(
     "transform", [lambda x: x.strftime("%Y-%m-%d"), lambda x: Timestamp(x)]
 )

pandas/tseries/holiday.py

@@ -4,6 +4,10 @@
     datetime,
     timedelta,
 )
+from typing import (
+    TYPE_CHECKING,
+    Callable,
+)
 import warnings
 
 from dateutil.relativedelta import (
@@ -33,6 +37,9 @@
     Easter,
 )
 
+if TYPE_CHECKING:
+    from pandas._libs.tslibs.offsets import BaseOffset
+
 
 def next_monday(dt: datetime) -> datetime:
     """
@@ -159,24 +166,34 @@ def __init__(
         year=None,
         month=None,
         day=None,
-        offset=None,
-        observance=None,
+        offset: BaseOffset | list[BaseOffset | list[BaseOffset]] | None = None,
+        observance: Callable | None = None,
         start_date=None,
         end_date=None,
-        days_of_week=None,
+        days_of_week: tuple | None = None,
     ) -> None:
         """
         Parameters
         ----------
         name : str
             Name of the holiday , defaults to class name
+        year : int, default None
+            Year of the holiday
+        month : int, default None
+            Month of the holiday
+        day : int, default None
+            Day of the holiday
         offset : array of pandas.tseries.offsets or
-                class from pandas.tseries.offsets
-            computes offset from date
-        observance: function
-            computes when holiday is given a pandas Timestamp
-        days_of_week:
-            provide a tuple of days e.g  (0,1,2,3,) for Monday Through Thursday
+                class from pandas.tseries.offsets, default None
+            Computes offset from date
+        observance : function, default None
+            Computes when holiday is given a pandas Timestamp
+        start_date : datetime-like, default None
+            First date the holiday is observed
+        end_date : datetime-like, default None
+            Last date the holiday is observed
+        days_of_week : tuple of int or dateutil.relativedelta weekday strs, default None
+            Provide a tuple of days e.g  (0,1,2,3,) for Monday Through Thursday
             Monday=0,..,Sunday=6
 
         Examples
@@ -223,7 +240,17 @@ class from pandas.tseries.offsets
         self.year = year
         self.month = month
         self.day = day
-        self.offset = offset
+        self.offset: None | BaseOffset | list[BaseOffset]
+        if isinstance(offset, list):
+            self.offset = []
+            for off in offset:
+                # check if we are handling composite offsets of another holiday
+                if isinstance(off, list):
+                    self.offset.extend(off)
+                else:
+                    self.offset.append(off)
+        else:
+            self.offset = offset
         self.start_date = (
             Timestamp(start_date) if start_date is not None else start_date
         )