DEPR: DatetimeIndex indexing with mismatched tzawareness (#49492)

* DEPR: DatetimeIndex indexing with mismatched tzawareness

* clarify whatsnew

doc/source/whatsnew/v2.0.0.rst

@@ -427,6 +427,7 @@ Removal of prior version deprecations/changes
 - Changed behavior of empty data passed into :class:`Series`; the default dtype will be ``object`` instead of ``float64`` (:issue:`29405`)
 - Changed the behavior of :meth:`DatetimeIndex.union`, :meth:`DatetimeIndex.intersection`, and :meth:`DatetimeIndex.symmetric_difference` with mismatched timezones to convert to UTC instead of casting to object dtype (:issue:`39328`)
 - Changed the behavior of :func:`to_datetime` with argument "now" with ``utc=False`` to match ``Timestamp("now")`` (:issue:`18705`)
+- Changed the behavior of indexing on a timezone-aware :class:`DatetimeIndex` with a timezone-naive ``datetime`` object or vice-versa; these now behave like any other non-comparable type by raising ``KeyError`` (:issue:`36148`)
 - Changed the behavior of :meth:`Index.reindex`, :meth:`Series.reindex`, and :meth:`DataFrame.reindex` with a ``datetime64`` dtype and a ``datetime.date`` object for ``fill_value``; these are no longer considered equivalent to ``datetime.datetime`` objects so the reindex casts to object dtype (:issue:`39767`)
 - Changed behavior of :meth:`SparseArray.astype` when given a dtype that is not explicitly ``SparseDtype``, cast to the exact requested dtype rather than silently using a ``SparseDtype`` instead (:issue:`34457`)
 - Changed behavior of :meth:`Index.ravel` to return a view on the original :class:`Index` instead of a ``np.ndarray`` (:issue:`36900`)

pandas/core/indexes/datetimes.py

@@ -552,31 +552,24 @@ def _parsed_string_to_bounds(self, reso: Resolution, parsed: datetime):
         end = self._maybe_cast_for_get_loc(end)
         return start, end
 
+    def _disallow_mismatched_indexing(self, key, one_way: bool = False) -> None:
+        """
+        Check for mismatched-tzawareness indexing and re-raise as KeyError.
+        """
+        try:
+            self._deprecate_mismatched_indexing(key, one_way=one_way)
+        except TypeError as err:
+            raise KeyError(key) from err
+
     def _deprecate_mismatched_indexing(self, key, one_way: bool = False) -> None:
         # GH#36148
         # we get here with isinstance(key, self._data._recognized_scalars)
-        try:
-            self._data._assert_tzawareness_compat(key)
-        except TypeError:
-            if self.tz is None:
-                msg = (
-                    "Indexing a timezone-naive DatetimeIndex with a "
-                    "timezone-aware datetime is deprecated and will "
-                    "raise KeyError in a future version.  "
-                    "Use a timezone-naive object instead."
-                )
-            elif one_way:
-                # we special-case timezone-naive strings and timezone-aware
-                #  DatetimeIndex
-                return
-            else:
-                msg = (
-                    "Indexing a timezone-aware DatetimeIndex with a "
-                    "timezone-naive datetime is deprecated and will "
-                    "raise KeyError in a future version. "
-                    "Use a timezone-aware object instead."
-                )
-            warnings.warn(msg, FutureWarning, stacklevel=find_stack_level())
+        if self.tz is not None and one_way:
+            # we special-case timezone-naive strings and timezone-aware
+            #  DatetimeIndex
+            return
+
+        self._data._assert_tzawareness_compat(key)
 
     def get_loc(self, key, method=None, tolerance=None):
         """
@@ -594,7 +587,7 @@ def get_loc(self, key, method=None, tolerance=None):
 
         if isinstance(key, self._data._recognized_scalars):
             # needed to localize naive datetimes
-            self._deprecate_mismatched_indexing(key)
+            self._disallow_mismatched_indexing(key)
             key = self._maybe_cast_for_get_loc(key)
 
         elif isinstance(key, str):
@@ -603,7 +596,7 @@ def get_loc(self, key, method=None, tolerance=None):
                 parsed, reso = self._parse_with_reso(key)
             except ValueError as err:
                 raise KeyError(key) from err
-            self._deprecate_mismatched_indexing(parsed, one_way=True)
+            self._disallow_mismatched_indexing(parsed, one_way=True)
 
             if self._can_partial_date_slice(reso):
                 try:

pandas/tests/frame/methods/test_reset_index.py

@@ -350,20 +350,14 @@ def test_reset_index_multiindex_nan(self):
     )
     def test_reset_index_with_datetimeindex_cols(self, name):
         # GH#5818
-        warn = None
-        if isinstance(name, Timestamp) and name.tz is not None:
-            # _deprecate_mismatched_indexing
-            warn = FutureWarning
-
         df = DataFrame(
             [[1, 2], [3, 4]],
             columns=date_range("1/1/2013", "1/2/2013"),
             index=["A", "B"],
         )
         df.index.name = name
 
-        with tm.assert_produces_warning(warn):
-            result = df.reset_index()
+        result = df.reset_index()
 
         item = name if name is not None else "index"
         columns = Index([item, datetime(2013, 1, 1), datetime(2013, 1, 2)])

pandas/tests/indexes/datetimes/test_indexing.py

@@ -718,11 +718,13 @@ def test_get_slice_bounds_datetime_within(
         index = bdate_range("2000-01-03", "2000-02-11").tz_localize(tz)
         key = box(year=2000, month=1, day=7)
 
-        warn = None if tz is None else FutureWarning
-        with tm.assert_produces_warning(warn):
-            # GH#36148 will require tzawareness-compat
+        if tz is not None:
+            with pytest.raises(TypeError, match="Cannot compare tz-naive"):
+                # GH#36148 we require tzawareness-compat as of 2.0
+                index.get_slice_bound(key, side=side)
+        else:
             result = index.get_slice_bound(key, side=side)
-        assert result == expected
+            assert result == expected
 
     @pytest.mark.parametrize("box", [datetime, Timestamp])
     @pytest.mark.parametrize("side", ["left", "right"])
@@ -735,11 +737,13 @@ def test_get_slice_bounds_datetime_outside(
         index = bdate_range("2000-01-03", "2000-02-11").tz_localize(tz)
         key = box(year=year, month=1, day=7)
 
-        warn = None if tz is None else FutureWarning
-        with tm.assert_produces_warning(warn):
-            # GH#36148 will require tzawareness-compat
+        if tz is not None:
+            with pytest.raises(TypeError, match="Cannot compare tz-naive"):
+                # GH#36148 we require tzawareness-compat as of 2.0
+                index.get_slice_bound(key, side=side)
+        else:
             result = index.get_slice_bound(key, side=side)
-        assert result == expected
+            assert result == expected
 
     @pytest.mark.parametrize("box", [datetime, Timestamp])
     def test_slice_datetime_locs(self, box, tz_aware_fixture):
@@ -748,12 +752,14 @@ def test_slice_datetime_locs(self, box, tz_aware_fixture):
         index = DatetimeIndex(["2010-01-01", "2010-01-03"]).tz_localize(tz)
         key = box(2010, 1, 1)
 
-        warn = None if tz is None else FutureWarning
-        with tm.assert_produces_warning(warn):
-            # GH#36148 will require tzawareness-compat
+        if tz is not None:
+            with pytest.raises(TypeError, match="Cannot compare tz-naive"):
+                # GH#36148 we require tzawareness-compat as of 2.0
+                index.slice_locs(key, box(2010, 1, 2))
+        else:
             result = index.slice_locs(key, box(2010, 1, 2))
-        expected = (0, 1)
-        assert result == expected
+            expected = (0, 1)
+            assert result == expected
 
 
 class TestIndexerBetweenTime:

pandas/tests/indexing/test_datetime.py

@@ -1,3 +1,7 @@
+import re
+
+import pytest
+
 import pandas as pd
 from pandas import (
     DataFrame,
@@ -17,14 +21,12 @@ def test_get_loc_naive_dti_aware_str_deprecated(self):
         ser = Series(range(100), index=dti)
 
         key = "2013-01-01 00:00:00.000000050+0000"
-        msg = "Indexing a timezone-naive DatetimeIndex with a timezone-aware datetime"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = ser[key]
-        assert res == 0
-
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            loc = dti.get_loc(key)
-        assert loc == 0
+        msg = re.escape(repr(key))
+        with pytest.raises(KeyError, match=msg):
+            ser[key]
+
+        with pytest.raises(KeyError, match=msg):
+            dti.get_loc(key)
 
     def test_indexing_with_datetime_tz(self):
 

pandas/tests/series/indexing/test_datetime.py

@@ -140,45 +140,43 @@ def test_getitem_setitem_datetimeindex():
     msg = "Cannot compare tz-naive and tz-aware datetime-like objects"
     naive = datetime(1990, 1, 1, 4)
     for key in [naive, Timestamp(naive), np.datetime64(naive, "ns")]:
-        with tm.assert_produces_warning(FutureWarning):
-            # GH#36148 will require tzawareness compat
-            result = ts[key]
-        expected = ts[4]
-        assert result == expected
+        with pytest.raises(KeyError, match=re.escape(repr(key))):
+            # GH#36148 as of 2.0 we require tzawareness-compat
+            ts[key]
 
     result = ts.copy()
-    with tm.assert_produces_warning(FutureWarning):
-        # GH#36148 will require tzawareness compat
-        result[datetime(1990, 1, 1, 4)] = 0
-    with tm.assert_produces_warning(FutureWarning):
-        # GH#36148 will require tzawareness compat
-        result[datetime(1990, 1, 1, 4)] = ts[4]
-    tm.assert_series_equal(result, ts)
+    # GH#36148 as of 2.0 we do not ignore tzawareness mismatch in indexing,
+    #  so setting it as a new key casts to object rather than matching
+    #  rng[4]
+    result[naive] = ts[4]
+    assert result.index.dtype == object
+    tm.assert_index_equal(result.index[:-1], rng.astype(object))
+    assert result.index[-1] == naive
 
-    with tm.assert_produces_warning(FutureWarning):
-        # GH#36148 will require tzawareness compat
-        result = ts[datetime(1990, 1, 1, 4) : datetime(1990, 1, 1, 7)]
-    expected = ts[4:8]
-    tm.assert_series_equal(result, expected)
+    msg = "Cannot compare tz-naive and tz-aware datetime-like objects"
+    with pytest.raises(TypeError, match=msg):
+        # GH#36148 require tzawareness compat as of 2.0
+        ts[naive : datetime(1990, 1, 1, 7)]
 
     result = ts.copy()
-    with tm.assert_produces_warning(FutureWarning):
-        # GH#36148 will require tzawareness compat
-        result[datetime(1990, 1, 1, 4) : datetime(1990, 1, 1, 7)] = 0
-    with tm.assert_produces_warning(FutureWarning):
-        # GH#36148 will require tzawareness compat
-        result[datetime(1990, 1, 1, 4) : datetime(1990, 1, 1, 7)] = ts[4:8]
+    with pytest.raises(TypeError, match=msg):
+        # GH#36148 require tzawareness compat as of 2.0
+        result[naive : datetime(1990, 1, 1, 7)] = 0
+    with pytest.raises(TypeError, match=msg):
+        # GH#36148 require tzawareness compat as of 2.0
+        result[naive : datetime(1990, 1, 1, 7)] = 99
+    # the __setitems__ here failed, so result should still match ts
     tm.assert_series_equal(result, ts)
 
-    lb = datetime(1990, 1, 1, 4)
+    lb = naive
     rb = datetime(1990, 1, 1, 7)
     msg = r"Invalid comparison between dtype=datetime64\[ns, US/Eastern\] and datetime"
     with pytest.raises(TypeError, match=msg):
         # tznaive vs tzaware comparison is invalid
         # see GH#18376, GH#18162
         ts[(ts.index >= lb) & (ts.index <= rb)]
 
-    lb = Timestamp(datetime(1990, 1, 1, 4)).tz_localize(rng.tzinfo)
+    lb = Timestamp(naive).tz_localize(rng.tzinfo)
     rb = Timestamp(datetime(1990, 1, 1, 7)).tz_localize(rng.tzinfo)
     result = ts[(ts.index >= lb) & (ts.index <= rb)]
     expected = ts[4:8]

pandas/tests/series/methods/test_truncate.py

@@ -1,5 +1,7 @@
 from datetime import datetime
 
+import pytest
+
 import pandas as pd
 from pandas import (
     Series,
@@ -13,8 +15,8 @@ def test_truncate_datetimeindex_tz(self):
         # GH 9243
         idx = date_range("4/1/2005", "4/30/2005", freq="D", tz="US/Pacific")
         s = Series(range(len(idx)), index=idx)
-        with tm.assert_produces_warning(FutureWarning):
-            # GH#36148 in the future will require tzawareness compat
+        with pytest.raises(TypeError, match="Cannot compare tz-naive"):
+            # GH#36148 as of 2.0 we require tzawareness compat
             s.truncate(datetime(2005, 4, 2), datetime(2005, 4, 4))
 
         lb = idx[1]