[3.12] GH-101588: Deprecate pickle/copy/deepcopy support in itertools (GH-104965) (GH-104997)

Doc/whatsnew/3.12.rst

@@ -1069,6 +1069,12 @@ Pending Removal in Python 3.14
   functions that have been deprecated since Python 2 but only gained a
   proper :exc:`DeprecationWarning` in 3.12. Remove them in 3.14.
 
+* :mod:`itertools` had undocumented, inefficient, historically buggy,
+  and inconsistent support for copy, deepcopy, and pickle operations.
+  This will be removed in 3.14 for a significant reduction in code
+  volume and maintenance burden.
+  (Contributed by Raymond Hettinger in :gh:`101588`.)
+
 * Accessing ``co_lnotab`` was deprecated in :pep:`626` since 3.10
   and was planned to be removed in 3.12
   but it only got a proper :exc:`DeprecationWarning` in 3.12.

Lib/test/test_itertools.py

@@ -15,6 +15,26 @@ import sys
 import struct
 import threading
 import gc
+import warnings
+
+def pickle_deprecated(testfunc):
+    """ Run the test three times.
+    First, verify that a Deprecation Warning is raised.
+    Second, run normally but with DeprecationWarnings temporarily disabled.
+    Third, run with warnings promoted to errors.
+    """
+    def inner(self):
+        with self.assertWarns(DeprecationWarning):
+            testfunc(self)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", category=DeprecationWarning)
+            testfunc(self)
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", category=DeprecationWarning)
+            with self.assertRaises((DeprecationWarning, AssertionError, SystemError)):
+                testfunc(self)
+
+    return inner
 
 maxsize = support.MAX_Py_ssize_t
 minsize = -maxsize-1
@@ -124,6 +144,7 @@ class TestBasicOps(unittest.TestCase):
             c = expand(compare[took:])
             self.assertEqual(a, c);
 
+    @pickle_deprecated
     def test_accumulate(self):
         self.assertEqual(list(accumulate(range(10))),               # one positional arg
                           [0, 1, 3, 6, 10, 15, 21, 28, 36, 45])
@@ -220,6 +241,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, list, chain.from_iterable([2, 3]))
         self.assertEqual(list(islice(chain.from_iterable(repeat(range(5))), 2)), [0, 1])
 
+    @pickle_deprecated
     def test_chain_reducible(self):
         for oper in [copy.deepcopy] + picklecopiers:
             it = chain('abc', 'def')
@@ -233,6 +255,7 @@ class TestBasicOps(unittest.TestCase):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             self.pickletest(proto, chain('abc', 'def'), compare=list('abcdef'))
 
+    @pickle_deprecated
     def test_chain_setstate(self):
         self.assertRaises(TypeError, chain().__setstate__, ())
         self.assertRaises(TypeError, chain().__setstate__, [])
@@ -246,6 +269,7 @@ class TestBasicOps(unittest.TestCase):
         it.__setstate__((iter(['abc', 'def']), iter(['ghi'])))
         self.assertEqual(list(it), ['ghi', 'a', 'b', 'c', 'd', 'e', 'f'])
 
+    @pickle_deprecated
     def test_combinations(self):
         self.assertRaises(TypeError, combinations, 'abc')       # missing r argument
         self.assertRaises(TypeError, combinations, 'abc', 2, 1) # too many arguments
@@ -269,7 +293,6 @@ class TestBasicOps(unittest.TestCase):
             self.assertEqual(list(op(testIntermediate)),
                              [(0,1,3), (0,2,3), (1,2,3)])
 
-
         def combinations1(iterable, r):
             'Pure python version shown in the docs'
             pool = tuple(iterable)
@@ -337,6 +360,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(len(set(map(id, combinations('abcde', 3)))), 1)
         self.assertNotEqual(len(set(map(id, list(combinations('abcde', 3))))), 1)
 
+    @pickle_deprecated
     def test_combinations_with_replacement(self):
         cwr = combinations_with_replacement
         self.assertRaises(TypeError, cwr, 'abc')       # missing r argument
@@ -425,6 +449,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(len(set(map(id, cwr('abcde', 3)))), 1)
         self.assertNotEqual(len(set(map(id, list(cwr('abcde', 3))))), 1)
 
+    @pickle_deprecated
     def test_permutations(self):
         self.assertRaises(TypeError, permutations)              # too few arguments
         self.assertRaises(TypeError, permutations, 'abc', 2, 1) # too many arguments
@@ -531,6 +556,7 @@ class TestBasicOps(unittest.TestCase):
                 self.assertEqual(comb, list(filter(set(perm).__contains__, cwr)))     # comb: cwr that is a perm
                 self.assertEqual(comb, sorted(set(cwr) & set(perm)))            # comb: both a cwr and a perm
 
+    @pickle_deprecated
     def test_compress(self):
         self.assertEqual(list(compress(data='ABCDEF', selectors=[1,0,1,0,1,1])), list('ACEF'))
         self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
@@ -564,7 +590,7 @@ class TestBasicOps(unittest.TestCase):
                     next(testIntermediate)
                     self.assertEqual(list(op(testIntermediate)), list(result2))
 
-
+    @pickle_deprecated
     def test_count(self):
         self.assertEqual(lzip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
         self.assertEqual(lzip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
@@ -613,6 +639,7 @@ class TestBasicOps(unittest.TestCase):
         #check proper internal error handling for large "step' sizes
         count(1, maxsize+5); sys.exc_info()
 
+    @pickle_deprecated
     def test_count_with_stride(self):
         self.assertEqual(lzip('abc',count(2,3)), [('a', 2), ('b', 5), ('c', 8)])
         self.assertEqual(lzip('abc',count(start=2,step=3)),
@@ -675,6 +702,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, cycle, 5)
         self.assertEqual(list(islice(cycle(gen3()),10)), [0,1,2,0,1,2,0,1,2,0])
 
+    @pickle_deprecated
     def test_cycle_copy_pickle(self):
         # check copy, deepcopy, pickle
         c = cycle('abc')
@@ -711,6 +739,7 @@ class TestBasicOps(unittest.TestCase):
             d = pickle.loads(p)                  # rebuild the cycle object
             self.assertEqual(take(20, d), list('cdeabcdeabcdeabcdeab'))
 
+    @pickle_deprecated
     def test_cycle_unpickle_compat(self):
         testcases = [
             b'citertools\ncycle\n(c__builtin__\niter\n((lI1\naI2\naI3\natRI1\nbtR((lI1\naI0\ntb.',
@@ -742,6 +771,7 @@ class TestBasicOps(unittest.TestCase):
             it = pickle.loads(t)
             self.assertEqual(take(10, it), [2, 3, 1, 2, 3, 1, 2, 3, 1, 2])
 
+    @pickle_deprecated
     def test_cycle_setstate(self):
         # Verify both modes for restoring state
 
@@ -778,6 +808,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertRaises(TypeError, cycle('').__setstate__, ())
         self.assertRaises(TypeError, cycle('').__setstate__, ([],))
 
+    @pickle_deprecated
     def test_groupby(self):
         # Check whether it accepts arguments correctly
         self.assertEqual([], list(groupby([])))
@@ -935,6 +966,7 @@ class TestBasicOps(unittest.TestCase):
             c = filter(isEven, range(6))
             self.pickletest(proto, c)
 
+    @pickle_deprecated
     def test_filterfalse(self):
         self.assertEqual(list(filterfalse(isEven, range(6))), [1,3,5])
         self.assertEqual(list(filterfalse(None, [0,1,0,2,0])), [0,0,0])
@@ -965,6 +997,7 @@ class TestBasicOps(unittest.TestCase):
                          lzip('abc', 'def'))
 
     @support.impl_detail("tuple reuse is specific to CPython")
+    @pickle_deprecated
     def test_zip_tuple_reuse(self):
         ids = list(map(id, zip('abc', 'def')))
         self.assertEqual(min(ids), max(ids))
@@ -1040,6 +1073,7 @@ class TestBasicOps(unittest.TestCase):
         ids = list(map(id, list(zip_longest('abc', 'def'))))
         self.assertEqual(len(dict.fromkeys(ids)), len(ids))
 
+    @pickle_deprecated
     def test_zip_longest_pickling(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             self.pickletest(proto, zip_longest("abc", "def"))
@@ -1186,6 +1220,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(len(set(map(id, product('abc', 'def')))), 1)
         self.assertNotEqual(len(set(map(id, list(product('abc', 'def'))))), 1)
 
+    @pickle_deprecated
     def test_product_pickling(self):
         # check copy, deepcopy, pickle
         for args, result in [
@@ -1201,6 +1236,7 @@ class TestBasicOps(unittest.TestCase):
             for proto in range(pickle.HIGHEST_PROTOCOL + 1):
                 self.pickletest(proto, product(*args))
 
+    @pickle_deprecated
     def test_product_issue_25021(self):
         # test that indices are properly clamped to the length of the tuples
         p = product((1, 2),(3,))
@@ -1211,6 +1247,7 @@ class TestBasicOps(unittest.TestCase):
         p.__setstate__((0, 0, 0x1000))  # will access tuple element 1 if not clamped
         self.assertRaises(StopIteration, next, p)
 
+    @pickle_deprecated
     def test_repeat(self):
         self.assertEqual(list(repeat(object='a', times=3)), ['a', 'a', 'a'])
         self.assertEqual(lzip(range(3),repeat('a')),
@@ -1243,6 +1280,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(repr(repeat('a', times=-1)), "repeat('a', 0)")
         self.assertEqual(repr(repeat('a', times=-2)), "repeat('a', 0)")
 
+    @pickle_deprecated
     def test_map(self):
         self.assertEqual(list(map(operator.pow, range(3), range(1,7))),
                          [0**1, 1**2, 2**3])
@@ -1273,6 +1311,7 @@ class TestBasicOps(unittest.TestCase):
             c = map(tupleize, 'abc', count())
             self.pickletest(proto, c)
 
+    @pickle_deprecated
     def test_starmap(self):
         self.assertEqual(list(starmap(operator.pow, zip(range(3), range(1,7)))),
                          [0**1, 1**2, 2**3])
@@ -1300,6 +1339,7 @@ class TestBasicOps(unittest.TestCase):
             c = starmap(operator.pow, zip(range(3), range(1,7)))
             self.pickletest(proto, c)
 
+    @pickle_deprecated
     def test_islice(self):
         for args in [          # islice(args) should agree with range(args)
                 (10, 20, 3),
@@ -1394,6 +1434,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(list(islice(range(100), IntLike(10), IntLike(50), IntLike(5))),
                          list(range(10,50,5)))
 
+    @pickle_deprecated
     def test_takewhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
         self.assertEqual(list(takewhile(underten, data)), [1, 3, 5])
@@ -1414,6 +1455,7 @@ class TestBasicOps(unittest.TestCase):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             self.pickletest(proto, takewhile(underten, data))
 
+    @pickle_deprecated
     def test_dropwhile(self):
         data = [1, 3, 5, 20, 2, 4, 6, 8]
         self.assertEqual(list(dropwhile(underten, data)), [20, 2, 4, 6, 8])
@@ -1431,6 +1473,7 @@ class TestBasicOps(unittest.TestCase):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             self.pickletest(proto, dropwhile(underten, data))
 
+    @pickle_deprecated
     def test_tee(self):
         n = 200
 
@@ -1732,6 +1775,7 @@ class TestExamples(unittest.TestCase):
     def test_accumulate(self):
         self.assertEqual(list(accumulate([1,2,3,4,5])), [1, 3, 6, 10, 15])
 
+    @pickle_deprecated
     def test_accumulate_reducible(self):
         # check copy, deepcopy, pickle
         data = [1, 2, 3, 4, 5]
@@ -1747,6 +1791,7 @@ class TestExamples(unittest.TestCase):
         self.assertEqual(list(copy.deepcopy(it)), accumulated[1:])
         self.assertEqual(list(copy.copy(it)), accumulated[1:])
 
+    @pickle_deprecated
     def test_accumulate_reducible_none(self):
         # Issue #25718: total is None
         it = accumulate([None, None, None], operator.is_)

Misc/NEWS.d/next/Library/2023-05-26-01-31-30.gh-issue-101588.RaqxFy.rst

@@ -0,0 +1 @@
+Deprecate undocumented copy/deepcopy/pickle support for itertools.

Modules/itertoolsmodule.c

@@ -93,6 +93,16 @@ class itertools.pairwise "pairwiseobject *" "clinic_state()->pairwise_type"
 #undef clinic_state_by_cls
 #undef clinic_state
 
+/* Deprecation of pickle support:  GH-101588 *********************************/
+
+#define ITERTOOL_PICKLE_DEPRECATION                                           \
+    if (PyErr_WarnEx(                                                         \
+            PyExc_DeprecationWarning,                                         \
+            "Itertool pickle/copy/deepcopy support "                          \
+            "will be removed in a Python 3.14.", 1) < 0) {                    \
+        return NULL;                                                          \
+    }
+
 /* batched object ************************************************************/
 
 /* Note:  The built-in zip() function includes a "strict" argument
@@ -506,6 +516,7 @@ groupby_reduce(groupbyobject *lz, PyObject *Py_UNUSED(ignored))
     /* reduce as a 'new' call with an optional 'setstate' if groupby
      * has started
      */
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *value;
     if (lz->tgtkey && lz->currkey && lz->currvalue)
         value = Py_BuildValue("O(OO)(OOO)", Py_TYPE(lz),
@@ -522,6 +533,7 @@ PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
 static PyObject *
 groupby_setstate(groupbyobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *currkey, *currvalue, *tgtkey;
     if (!PyTuple_Check(state)) {
         PyErr_SetString(PyExc_TypeError, "state is not a tuple");
@@ -660,6 +672,7 @@ _grouper_next(_grouperobject *igo)
 static PyObject *
 _grouper_reduce(_grouperobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (((groupbyobject *)lz->parent)->currgrouper != lz) {
         return Py_BuildValue("N(())", _PyEval_GetBuiltin(&_Py_ID(iter)));
     }
@@ -828,6 +841,7 @@ teedataobject_dealloc(teedataobject *tdo)
 static PyObject *
 teedataobject_reduce(teedataobject *tdo, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     int i;
     /* create a temporary list of already iterated values */
     PyObject *values = PyList_New(tdo->numread);
@@ -1041,12 +1055,14 @@ tee_dealloc(teeobject *to)
 static PyObject *
 tee_reduce(teeobject *to, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     return Py_BuildValue("O(())(Oi)", Py_TYPE(to), to->dataobj, to->index);
 }
 
 static PyObject *
 tee_setstate(teeobject *to, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     teedataobject *tdo;
     int index;
     if (!PyTuple_Check(state)) {
@@ -1275,6 +1291,7 @@ cycle_next(cycleobject *lz)
 static PyObject *
 cycle_reduce(cycleobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     /* Create a new cycle with the iterator tuple, then set the saved state */
     if (lz->it == NULL) {
         PyObject *it = PyObject_GetIter(lz->saved);
@@ -1298,6 +1315,7 @@ cycle_reduce(cycleobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 cycle_setstate(cycleobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *saved=NULL;
     int firstpass;
     if (!PyTuple_Check(state)) {
@@ -1446,12 +1464,14 @@ dropwhile_next(dropwhileobject *lz)
 static PyObject *
 dropwhile_reduce(dropwhileobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     return Py_BuildValue("O(OO)l", Py_TYPE(lz), lz->func, lz->it, lz->start);
 }
 
 static PyObject *
 dropwhile_setstate(dropwhileobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     int start = PyObject_IsTrue(state);
     if (start < 0)
         return NULL;
@@ -1584,12 +1604,14 @@ takewhile_next(takewhileobject *lz)
 static PyObject *
 takewhile_reduce(takewhileobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     return Py_BuildValue("O(OO)l", Py_TYPE(lz), lz->func, lz->it, lz->stop);
 }
 
 static PyObject *
 takewhile_reduce_setstate(takewhileobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     int stop = PyObject_IsTrue(state);
 
     if (stop < 0)
@@ -1786,6 +1808,7 @@ empty:
 static PyObject *
 islice_reduce(isliceobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     /* When unpickled, generate a new object with the same bounds,
      * then 'setstate' with the next and count
      */
@@ -1818,6 +1841,7 @@ islice_reduce(isliceobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 islice_setstate(isliceobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     Py_ssize_t cnt = PyLong_AsSsize_t(state);
 
     if (cnt == -1 && PyErr_Occurred())
@@ -1953,6 +1977,7 @@ starmap_next(starmapobject *lz)
 static PyObject *
 starmap_reduce(starmapobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     /* Just pickle the iterator */
     return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
 }
@@ -2109,6 +2134,7 @@ chain_next(chainobject *lz)
 static PyObject *
 chain_reduce(chainobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (lz->source) {
         /* we can't pickle function objects (itertools.from_iterable) so
          * we must use setstate to replace the iterable.  One day we
@@ -2128,6 +2154,7 @@ chain_reduce(chainobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 chain_setstate(chainobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *source, *active=NULL;
 
     if (!PyTuple_Check(state)) {
@@ -2403,6 +2430,7 @@ empty:
 static PyObject *
 product_reduce(productobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (lz->stopped) {
         return Py_BuildValue("O(())", Py_TYPE(lz));
     } else if (lz->result == NULL) {
@@ -2433,6 +2461,7 @@ product_reduce(productobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 product_setstate(productobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *result;
     Py_ssize_t n, i;
 
@@ -2711,6 +2740,7 @@ empty:
 static PyObject *
 combinations_reduce(combinationsobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (lz->result == NULL) {
         return Py_BuildValue("O(On)", Py_TYPE(lz), lz->pool, lz->r);
     } else if (lz->stopped) {
@@ -2740,6 +2770,7 @@ combinations_reduce(combinationsobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 combinations_setstate(combinationsobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *result;
     Py_ssize_t i;
     Py_ssize_t n = PyTuple_GET_SIZE(lz->pool);
@@ -3019,6 +3050,7 @@ empty:
 static PyObject *
 cwr_reduce(cwrobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (lz->result == NULL) {
         return Py_BuildValue("O(On)", Py_TYPE(lz), lz->pool, lz->r);
     } else if (lz->stopped) {
@@ -3047,6 +3079,7 @@ cwr_reduce(cwrobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 cwr_setstate(cwrobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *result;
     Py_ssize_t n, i;
 
@@ -3354,6 +3387,7 @@ empty:
 static PyObject *
 permutations_reduce(permutationsobject *po, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (po->result == NULL) {
         return Py_BuildValue("O(On)", Py_TYPE(po), po->pool, po->r);
     } else if (po->stopped) {
@@ -3396,6 +3430,7 @@ permutations_reduce(permutationsobject *po, PyObject *Py_UNUSED(ignored))
 static PyObject *
 permutations_setstate(permutationsobject *po, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     PyObject *indices, *cycles, *result;
     Py_ssize_t n, i;
 
@@ -3593,6 +3628,7 @@ accumulate_next(accumulateobject *lz)
 static PyObject *
 accumulate_reduce(accumulateobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     itertools_state *state = lz->state;
 
     if (lz->initial != Py_None) {
@@ -3628,6 +3664,7 @@ accumulate_reduce(accumulateobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 accumulate_setstate(accumulateobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     Py_INCREF(state);
     Py_XSETREF(lz->total, state);
     Py_RETURN_NONE;
@@ -3776,6 +3813,7 @@ compress_next(compressobject *lz)
 static PyObject *
 compress_reduce(compressobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     return Py_BuildValue("O(OO)", Py_TYPE(lz),
         lz->data, lz->selectors);
 }
@@ -3908,6 +3946,7 @@ filterfalse_next(filterfalseobject *lz)
 static PyObject *
 filterfalse_reduce(filterfalseobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
 }
 
@@ -4135,6 +4174,7 @@ count_repr(countobject *lz)
 static PyObject *
 count_reduce(countobject *lz, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     if (lz->cnt == PY_SSIZE_T_MAX)
         return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->long_cnt, lz->long_step);
     return Py_BuildValue("O(n)", Py_TYPE(lz), lz->cnt);
@@ -4258,6 +4298,7 @@ PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(
 static PyObject *
 repeat_reduce(repeatobject *ro, PyObject *Py_UNUSED(ignored))
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     /* unpickle this so that a new repeat iterator is constructed with an
      * object, then call __setstate__ on it to set cnt
      */
@@ -4478,7 +4519,7 @@ zip_longest_next(ziplongestobject *lz)
 static PyObject *
 zip_longest_reduce(ziplongestobject *lz, PyObject *Py_UNUSED(ignored))
 {
-
+    ITERTOOL_PICKLE_DEPRECATION;
     /* Create a new tuple with empty sequences where appropriate to pickle.
      * Then use setstate to set the fillvalue
      */
@@ -4505,6 +4546,7 @@ zip_longest_reduce(ziplongestobject *lz, PyObject *Py_UNUSED(ignored))
 static PyObject *
 zip_longest_setstate(ziplongestobject *lz, PyObject *state)
 {
+    ITERTOOL_PICKLE_DEPRECATION;
     Py_INCREF(state);
     Py_XSETREF(lz->fillvalue, state);
     Py_RETURN_NONE;