BUG: fillna maximum recursion depth exceeded in cmp (GH18159).

Author: Krzysztof Chomski

doc/source/whatsnew/v0.21.1.txt

@@ -64,6 +64,7 @@ Bug Fixes
 - Bug in ``pd.concat`` when empty and non-empty DataFrames or Series are concatenated (:issue:`18178` :issue:`18187`)
 - Bug in :class:`IntervalIndex` constructor when a list of intervals is passed with non-default ``closed`` (:issue:`18334`)
 - Bug in :meth:`IntervalIndex.copy` when copying and ``IntervalIndex`` with non-default ``closed`` (:issue:`18339`)
+- Bug in :meth:`fillna` maximum recursion depth exceeded in cmp (:issue:`18159`).
 
 Conversion
 ^^^^^^^^^^

pandas/core/internals.py

@@ -1847,8 +1847,9 @@ def _can_hold_element(self, element):
         if tipo is not None:
             return (issubclass(tipo.type, (np.floating, np.integer)) and
                     not issubclass(tipo.type, (np.datetime64, np.timedelta64)))
-        return (isinstance(element, (float, int, np.floating, np.int_)) and
-                not isinstance(element, (bool, np.bool_, datetime, timedelta,
+        return (
+            isinstance(element, (float, int, np.floating, np.int_, np.long))
+            and not isinstance(element, (bool, np.bool_, datetime, timedelta,
                                          np.datetime64, np.timedelta64)))
 
     def to_native_types(self, slicer=None, na_rep='', float_format=None,

pandas/tests/internals/test_internals.py

@@ -1222,6 +1222,7 @@ class TestCanHoldElement(object):
     @pytest.mark.parametrize('value, dtype', [
         (1, 'i8'),
         (1.0, 'f8'),
+        (2**63, 'f8'),
         (1j, 'complex128'),
         (True, 'bool'),
         (np.timedelta64(20, 'ns'), '<m8[ns]'),