BUG: construct_1d_ndarray_preserving_na with dt64/td64 and object dtype (#40068)

Author: jbrockmendel

pandas/core/dtypes/cast.py

@@ -1829,7 +1829,16 @@ def construct_1d_ndarray_preserving_na(
     else:
         if dtype is not None:
             _disallow_mismatched_datetimelike(values, dtype)
-        subarr = np.array(values, dtype=dtype, copy=copy)
+
+        if (
+            dtype == object
+            and isinstance(values, np.ndarray)
+            and values.dtype.kind in ["m", "M"]
+        ):
+            # TODO(numpy#12550): special-case can be removed
+            subarr = construct_1d_object_array_from_listlike(list(values))
+        else:
+            subarr = np.array(values, dtype=dtype, copy=copy)
 
     return subarr
 

pandas/tests/dtypes/cast/test_construct_ndarray.py

@@ -19,3 +19,13 @@
 def test_construct_1d_ndarray_preserving_na(values, dtype, expected):
     result = construct_1d_ndarray_preserving_na(values, dtype=dtype)
     tm.assert_numpy_array_equal(result, expected)
+
+
+@pytest.mark.parametrize("dtype", ["m8[ns]", "M8[ns]"])
+def test_construct_1d_ndarray_preserving_na_datetimelike(dtype):
+    arr = np.arange(5, dtype=np.int64).view(dtype)
+    expected = np.array(list(arr), dtype=object)
+    assert all(isinstance(x, type(arr[0])) for x in expected)
+
+    result = construct_1d_ndarray_preserving_na(arr, np.dtype(object))
+    tm.assert_numpy_array_equal(result, expected)