BUG: handle ExtensionArray in Series._flex_method with fill_value (fixes #62467)

Author: Mayank

pandas/core/series.py

@@ -6062,7 +6062,7 @@ def _flex_method(self, other, op, *, level=None, fill_value=None, axis: Axis = 0
 
         if isinstance(other, Series):
             return self._binop(other, op, level=level, fill_value=fill_value)
-        elif isinstance(other, (np.ndarray, list, tuple)):
+        elif isinstance(other, (np.ndarray, list, tuple, ExtensionArray)):
             if len(other) != len(self):
                 raise ValueError("Lengths must be equal")
             other = self._constructor(other, self.index, copy=False)

pandas/tests/series/test_arithmetic.py

@@ -45,6 +45,13 @@ def _permute(obj):
 
 
 class TestSeriesFlexArithmetic:
+    def test_flex_op_with_extensionarray_and_fill_value(self):
+        # GH#62467 ensure ExtensionArray "other" with fill_value works
+        left = Series([pd.Timestamp(2025, 8, 20)] * 2)
+        right = left._values  # ExtensionArray (DatetimeArray)
+        result = left.sub(right, fill_value=left[0])
+        expected = Series([Timedelta(0), Timedelta(0)])
+        tm.assert_series_equal(result, expected)
     @pytest.mark.parametrize(
         "ts",
         [