REF: date arg not reachable in DTI._maybe_cast_slice_bound (pandas-dev#42855)

Author: jbrockmendel

pandas/core/indexes/datetimes.py

@@ -722,7 +722,7 @@ def _maybe_cast_slice_bound(self, label, side: str, kind=lib.no_default):
             if self._is_strictly_monotonic_decreasing and len(self) > 1:
                 return upper if side == "left" else lower
             return lower if side == "left" else upper
-        elif isinstance(label, (self._data._recognized_scalars, date)):
+        elif isinstance(label, self._data._recognized_scalars):
             self._deprecate_mismatched_indexing(label)
         else:
             raise self._invalid_indexer("slice", label)
@@ -802,6 +802,13 @@ def check_str_or_none(point):
         else:
             return indexer
 
+    @doc(Index.get_slice_bound)
+    def get_slice_bound(self, label, side: str, kind=None) -> int:
+        # GH#42855 handle date here instead of _maybe_cast_slice_bound
+        if isinstance(label, date) and not isinstance(label, datetime):
+            label = Timestamp(label).to_pydatetime()
+        return super().get_slice_bound(label, side=side, kind=kind)
+
     # --------------------------------------------------------------------
 
     @property

pandas/tests/indexes/datetimes/test_indexing.py

@@ -746,7 +746,7 @@ def test_get_slice_bounds_datetime_within(
             result = index.get_slice_bound(key, kind=kind, side=side)
         assert result == expected
 
-    @pytest.mark.parametrize("box", [date, datetime, Timestamp])
+    @pytest.mark.parametrize("box", [datetime, Timestamp])
     @pytest.mark.parametrize("kind", ["getitem", "loc", None])
     @pytest.mark.parametrize("side", ["left", "right"])
     @pytest.mark.parametrize("year, expected", [(1999, 0), (2020, 30)])
@@ -764,7 +764,7 @@ def test_get_slice_bounds_datetime_outside(
             result = index.get_slice_bound(key, kind=kind, side=side)
         assert result == expected
 
-    @pytest.mark.parametrize("box", [date, datetime, Timestamp])
+    @pytest.mark.parametrize("box", [datetime, Timestamp])
     @pytest.mark.parametrize("kind", ["getitem", "loc", None])
     def test_slice_datetime_locs(self, box, kind, tz_aware_fixture):
         # GH 34077