BUG: #29049 make holiday support offsets of offsets

pandas/tests/tseries/holiday/test_holiday.py

@@ -271,6 +271,24 @@ def test_both_offset_observance_raises():
         )
 
 
+def test_list_of_list_of_offsets_raises():
+    # see gh-29049
+    # Test that the offsets of offsets are forbidden
+    holiday1 = Holiday(
+        "Holiday1",
+        month=USThanksgivingDay.month,
+        day=USThanksgivingDay.day,
+        offset=[USThanksgivingDay.offset, DateOffset(1)],
+    )
+    with pytest.raises(ValueError, match="Nested lists are not supported for offset"):
+        Holiday(
+            "Holiday2",
+            month=holiday1.month,
+            day=holiday1.day,
+            offset=[holiday1.offset, DateOffset(3)],
+        )
+
+
 def test_half_open_interval_with_observance():
     # Prompted by GH 49075
     # Check for holidays that have a half-open date interval where

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:
     """
@@ -149,6 +156,7 @@ class Holiday:
     for observance.
     """
 
+    offset: BaseOffset | list[BaseOffset] | None
     start_date: Timestamp | None
     end_date: Timestamp | None
     days_of_week: tuple[int, ...] | None
@@ -159,24 +167,34 @@ def __init__(
         year=None,
         month=None,
         day=None,
-        offset=None,
-        observance=None,
+        offset: 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
@@ -218,6 +236,11 @@ class from pandas.tseries.offsets
         """
         if offset is not None and observance is not None:
             raise NotImplementedError("Cannot use both offset and observance.")
+        if isinstance(offset, list) and any(isinstance(off, list) for off in offset):
+            raise ValueError(
+                "Nested lists are not supported for offset. "
+                "Flatten composite offsets of `Holiday.offset`s first."
+            )
 
         self.name = name
         self.year = year