BUG: fix+test assigning invalid NAT-like to DTA/TDA/PA

pandas/core/arrays/datetimelike.py

@@ -492,7 +492,7 @@ def __setitem__(
         elif isinstance(value, self._scalar_type):
             self._check_compatible_with(value)
             value = self._unbox_scalar(value)
-        elif isna(value) or value == iNaT:
+        elif is_valid_na(value, self.dtype) or value == iNaT:
             value = iNaT
         else:
             msg = (
@@ -1679,3 +1679,27 @@ def _ensure_datetimelike_to_i8(other, to_utc=False):
             # period array cannot be coerced to int
             other = Index(other)
     return other.asi8
+
+
+def is_valid_na(obj, dtype):
+    """
+    isna check that excludes incompatible dtypes
+
+    Parameters
+    ----------
+    obj : object
+    dtype : np.datetime64, np.timedelta64, DatetimeTZDtype, or PeriodDtype
+
+    Returns
+    -------
+    bool
+    """
+    if not isna(obj):
+        return False
+    if dtype.kind == "M":
+        return not isinstance(obj, np.timedelta64)
+    if dtype.kind == "m":
+        return not isinstance(obj, np.datetime64)
+
+    # must be PeriodDType
+    return not isinstance(obj, (np.datetime64, np.timedelta64))

pandas/tests/arrays/test_datetimelike.py

@@ -651,3 +651,39 @@ def test_array_interface(self, period_index):
         result = np.asarray(arr, dtype="S20")
         expected = np.asarray(arr).astype("S20")
         tm.assert_numpy_array_equal(result, expected)
+
+
+@pytest.mark.parametrize(
+    "array",
+    [
+        pd.TimedeltaIndex(["1 Day", "3 Hours", "NaT"])._data,
+        pd.date_range("2000-01-01", periods=3, freq="D")._data,
+        pd.period_range("2000-01-01", periods=3, freq="D")._data,
+    ],
+    ids=lambda x: type(x).__name__,
+)
+def test_nat_assignment_array(array):
+    expected = type(array)._from_sequence([pd.NaT, array[1], array[2]])
+
+    all_nats = [pd.NaT, np.timedelta64("NaT", "ns"), np.datetime64("NaT", "ns")]
+    casting_nats = {
+        TimedeltaArray: [pd.NaT, np.timedelta64("NaT", "ns")],
+        DatetimeArray: [pd.NaT, np.datetime64("NaT", "ns")],
+        PeriodArray: [pd.NaT],
+    }[type(array)]
+    non_casting_nats = {
+        TimedeltaArray: [np.datetime64("NaT", "ns")],
+        DatetimeArray: [np.timedelta64("NaT", "ns")],
+        PeriodArray: [np.timedelta64("NaT", "ns"), np.datetime64("NaT", "ns")],
+    }[type(array)]
+
+    for nat in casting_nats:
+        arr = array.copy()
+        arr[0] = nat
+
+        tm.assert_equal(arr, expected)
+
+    for nat in non_casting_nats:
+        arr = array.copy()
+        with pytest.raises(TypeError):
+            arr[0] = nat