cast index to TimedeltaArray

Author: natmokval

pandas/tseries/frequencies.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import (
+    TYPE_CHECKING,
+    cast,
+)
 
 import numpy as np
 
@@ -49,9 +52,9 @@
     from pandas import (
         DatetimeIndex,
         Series,
-        TimedeltaArray,
         TimedeltaIndex,
     )
+    from pandas.core.arrays import TimedeltaArray
     from pandas.core.arrays.datetimelike import DatetimeLikeArrayMixin
 # ---------------------------------------------------------------------
 # Offset names ("time rules") and related functions
@@ -177,7 +180,8 @@ def infer_freq(
             raise TypeError(
                 f"cannot infer freq from a non-convertible index of dtype {index.dtype}"
             )
-        index: TimedeltaArray = index
+
+        index = cast("TimedeltaArray", index)
 
     if not isinstance(index, DatetimeIndex):
         index = DatetimeIndex(index)