DEPR: dt64 any/all GH#34479

doc/source/whatsnew/v2.0.0.rst

@@ -638,6 +638,7 @@ Deprecations
 - :meth:`Index.holds_integer` has been deprecated. Use :func:`pandas.api.types.infer_dtype` instead (:issue:`50243`)
 - :meth:`Index.is_categorical` has been deprecated. Use :func:`pandas.api.types.is_categorical_dtype` instead (:issue:`50042`)
 - :meth:`Index.is_interval` has been deprecated. Use :func:`pandas.api.types.is_intterval_dtype` instead (:issue:`50042`)
+- Deprecated ``all`` and ``any`` reductions with ``datetime64`` and :class:`DatetimeTZDtype` dtypes, use e.g. ``(obj != pd.Timestamp(0), tz=obj.tz).all()`` instead (:issue:`34479`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/arrays/datetimelike.py

@@ -2034,11 +2034,12 @@ def ceil(
     # Reductions
 
     def any(self, *, axis: AxisInt | None = None, skipna: bool = True) -> bool:
-        # GH#34479 discussion of desired behavior long-term
+        # GH#34479 the nanops call will issue a FutureWarning for non-td64 dtype
         return nanops.nanany(self._ndarray, axis=axis, skipna=skipna, mask=self.isna())
 
     def all(self, *, axis: AxisInt | None = None, skipna: bool = True) -> bool:
-        # GH#34479 discussion of desired behavior long-term
+        # GH#34479 the nanops call will issue a FutureWarning for non-td64 dtype
+
         return nanops.nanall(self._ndarray, axis=axis, skipna=skipna, mask=self.isna())
 
     # --------------------------------------------------------------

pandas/core/nanops.py

@@ -32,6 +32,7 @@
     npt,
 )
 from pandas.compat._optional import import_optional_dependency
+from pandas.util._exceptions import find_stack_level
 
 from pandas.core.dtypes.common import (
     is_any_int_dtype,
@@ -529,6 +530,15 @@ def nanany(
     >>> nanops.nanany(s)
     False
     """
+    if needs_i8_conversion(values.dtype) and values.dtype.kind != "m":
+        # GH#34479
+        warnings.warn(
+            "'any' with datetime64 dtypes is deprecated and will raise in a "
+            "future version. Use (obj != pd.Timestamp(0)).any() instead.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
+
     values, _, _, _, _ = _get_values(values, skipna, fill_value=False, mask=mask)
 
     # For object type, any won't necessarily return
@@ -575,6 +585,15 @@ def nanall(
     >>> nanops.nanall(s)
     False
     """
+    if needs_i8_conversion(values.dtype) and values.dtype.kind != "m":
+        # GH#34479
+        warnings.warn(
+            "'all' with datetime64 dtypes is deprecated and will raise in a "
+            "future version. Use (obj != pd.Timestamp(0)).all() instead.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
+
     values, _, _, _, _ = _get_values(values, skipna, fill_value=True, mask=mask)
 
     # For object type, all won't necessarily return

pandas/tests/frame/test_reductions.py

@@ -1138,6 +1138,10 @@ def test_any_all_object_dtype(self, axis, bool_agg_func, skipna):
         expected = Series([True, True, True, True])
         tm.assert_series_equal(result, expected)
 
+    # GH#50947 deprecates this but it is not emitting a warning in some builds.
+    @pytest.mark.filterwarnings(
+        "ignore:'any' with datetime64 dtypes is deprecated.*:FutureWarning"
+    )
     def test_any_datetime(self):
 
         # GH 23070
@@ -1151,6 +1155,7 @@ def test_any_datetime(self):
         df = DataFrame({"A": float_data, "B": datetime_data})
 
         result = df.any(axis=1)
+
         expected = Series([True, True, True, False])
         tm.assert_series_equal(result, expected)
 
@@ -1245,12 +1250,22 @@ def test_any_all_np_func(self, func, data, expected):
             ):
                 getattr(DataFrame(data), func.__name__)(axis=None)
         else:
-            result = func(data)
+            msg = "'(any|all)' with datetime64 dtypes is deprecated"
+            if data.dtypes.apply(lambda x: x.kind == "M").any():
+                warn = FutureWarning
+            else:
+                warn = None
+
+            with tm.assert_produces_warning(warn, match=msg, check_stacklevel=False):
+                # GH#34479
+                result = func(data)
             assert isinstance(result, np.bool_)
             assert result.item() is expected
 
             # method version
-            result = getattr(DataFrame(data), func.__name__)(axis=None)
+            with tm.assert_produces_warning(warn, match=msg):
+                # GH#34479
+                result = getattr(DataFrame(data), func.__name__)(axis=None)
             assert isinstance(result, np.bool_)
             assert result.item() is expected
 

pandas/tests/reductions/test_reductions.py

@@ -985,27 +985,32 @@ def test_any_all_datetimelike(self):
         ser = Series(dta)
         df = DataFrame(ser)
 
-        assert dta.all()
-        assert dta.any()
+        msg = "'(any|all)' with datetime64 dtypes is deprecated"
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            # GH#34479
+            assert dta.all()
+            assert dta.any()
 
-        assert ser.all()
-        assert ser.any()
+            assert ser.all()
+            assert ser.any()
 
-        assert df.any().all()
-        assert df.all().all()
+            assert df.any().all()
+            assert df.all().all()
 
         dta = dta.tz_localize("UTC")
         ser = Series(dta)
         df = DataFrame(ser)
 
-        assert dta.all()
-        assert dta.any()
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            # GH#34479
+            assert dta.all()
+            assert dta.any()
 
-        assert ser.all()
-        assert ser.any()
+            assert ser.all()
+            assert ser.any()
 
-        assert df.any().all()
-        assert df.all().all()
+            assert df.any().all()
+            assert df.all().all()
 
         tda = dta - dta[0]
         ser = Series(tda)