From 8598eb52d96a97a36f773a3c429c0e468ad6c08e Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:06:43 -0400
Subject: [PATCH 01/17] Add the utility.

Also use it in _bz2.
---
 Include/cpython/object.h |  4 ++++
 Modules/_bz2module.c     | 18 ++----------------
 Objects/object.c         |  7 +++++++
 3 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/Include/cpython/object.h b/Include/cpython/object.h
index 973d358ed8e4ec..b244c062c7679e 100644
--- a/Include/cpython/object.h
+++ b/Include/cpython/object.h
@@ -491,3 +491,7 @@ PyAPI_FUNC(int) PyUnstable_TryIncRef(PyObject *);
 PyAPI_FUNC(void) PyUnstable_EnableTryIncRef(PyObject *);
 
 PyAPI_FUNC(int) PyUnstable_Object_IsUniquelyReferenced(PyObject *);
+
+/* Utility for the tp_traverse slot of mutable heap types that have no other
+ * references. */
+PyAPI_FUNC(int) _PyObject_VisitType(PyObject *op, visitproc visit, void *arg);
diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 914172684158a1..73c5546af60b64 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -391,13 +391,6 @@ BZ2Compressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
-static int
-BZ2Compressor_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyMethodDef BZ2Compressor_methods[] = {
     _BZ2_BZ2COMPRESSOR_COMPRESS_METHODDEF
     _BZ2_BZ2COMPRESSOR_FLUSH_METHODDEF
@@ -409,7 +402,7 @@ static PyType_Slot bz2_compressor_type_slots[] = {
     {Py_tp_methods, BZ2Compressor_methods},
     {Py_tp_new, _bz2_BZ2Compressor},
     {Py_tp_doc, (char *)_bz2_BZ2Compressor__doc__},
-    {Py_tp_traverse, BZ2Compressor_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 
@@ -703,13 +696,6 @@ BZ2Decompressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
-static int
-BZ2Decompressor_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyMethodDef BZ2Decompressor_methods[] = {
     _BZ2_BZ2DECOMPRESSOR_DECOMPRESS_METHODDEF
     {NULL}
@@ -740,7 +726,7 @@ static PyType_Slot bz2_decompressor_type_slots[] = {
     {Py_tp_doc, (char *)_bz2_BZ2Decompressor__doc__},
     {Py_tp_members, BZ2Decompressor_members},
     {Py_tp_new, _bz2_BZ2Decompressor},
-    {Py_tp_traverse, BZ2Decompressor_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 
diff --git a/Objects/object.c b/Objects/object.c
index fba86e63cd4a11..c8dc7acecea0bd 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -3384,3 +3384,10 @@ PyUnstable_Object_IsUniquelyReferenced(PyObject *op)
     assert(op != NULL);
     return _PyObject_IsUniquelyReferenced(op);
 }
+
+int _PyObject_VisitType(PyObject *op, visitproc visit, void *arg)
+{
+    assert(op != NULL);
+    Py_VISIT(Py_TYPE(op));
+    return 0;
+}

From 856026024897968bcf9d1de15caf57390b5f7d58 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:07:29 -0400
Subject: [PATCH 02/17] Remove boilerplate in _dbm.

---
 Modules/_dbmmodule.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/Modules/_dbmmodule.c b/Modules/_dbmmodule.c
index 0cd0f043de453d..17aca2f00a13c0 100644
--- a/Modules/_dbmmodule.c
+++ b/Modules/_dbmmodule.c
@@ -96,12 +96,6 @@ newdbmobject(_dbm_state *state, const char *file, int flags, int mode)
 }
 
 /* Methods */
-static int
-dbm_traverse(PyObject *dp, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(dp));
-    return 0;
-}
 
 static void
 dbm_dealloc(PyObject *self)
@@ -540,7 +534,7 @@ static PyMethodDef dbm_methods[] = {
 
 static PyType_Slot dbmtype_spec_slots[] = {
     {Py_tp_dealloc, dbm_dealloc},
-    {Py_tp_traverse, dbm_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_methods, dbm_methods},
     {Py_sq_contains, dbm_contains},
     {Py_mp_length, dbm_length},

From d7a5fd8e6674b33ab2494f41ffd1df8154f1e890 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:07:56 -0400
Subject: [PATCH 03/17] Remove boilerplate in _functools.

---
 Modules/_functoolsmodule.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index f077a0ed329516..257d5c6d53611c 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -108,20 +108,13 @@ placeholder_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
     return placeholder;
 }
 
-static int
-placeholder_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyType_Slot placeholder_type_slots[] = {
     {Py_tp_dealloc, placeholder_dealloc},
     {Py_tp_repr, placeholder_repr},
     {Py_tp_doc, (void *)placeholder_doc},
     {Py_tp_methods, placeholder_methods},
     {Py_tp_new, placeholder_new},
-    {Py_tp_traverse, placeholder_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 

From b9751b3989abe0de8c4924c99a055eca0d8afb31 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:09:14 -0400
Subject: [PATCH 04/17] Use it in _gdbm, _lzma, and _ssl.

---
 Modules/_gdbmmodule.c |  8 +-------
 Modules/_lzmamodule.c | 18 ++----------------
 Modules/_pickle.c     |  9 +--------
 Modules/_ssl.c        |  9 +--------
 4 files changed, 5 insertions(+), 39 deletions(-)

diff --git a/Modules/_gdbmmodule.c b/Modules/_gdbmmodule.c
index 76072ca60cf6cd..87f62b945b2923 100644
--- a/Modules/_gdbmmodule.c
+++ b/Modules/_gdbmmodule.c
@@ -122,12 +122,6 @@ newgdbmobject(_gdbm_state *state, const char *file, int flags, int mode)
 }
 
 /* Methods */
-static int
-gdbm_traverse(PyObject *op, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(op));
-    return 0;
-}
 
 static void
 gdbm_dealloc(PyObject *op)
@@ -714,7 +708,7 @@ static PyMethodDef gdbm_methods[] = {
 
 static PyType_Slot gdbmtype_spec_slots[] = {
     {Py_tp_dealloc, gdbm_dealloc},
-    {Py_tp_traverse, gdbm_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_methods, gdbm_methods},
     {Py_sq_contains, gdbm_contains},
     {Py_mp_length, gdbm_length},
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
index 0b0b1bc765bbc9..30a42ccb0082b8 100644
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -882,13 +882,6 @@ static PyMethodDef Compressor_methods[] = {
     {NULL}
 };
 
-static int
-Compressor_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 PyDoc_STRVAR(Compressor_doc,
 "LZMACompressor(format=FORMAT_XZ, check=-1, preset=None, filters=None)\n"
 "\n"
@@ -922,7 +915,7 @@ static PyType_Slot lzma_compressor_type_slots[] = {
     {Py_tp_methods, Compressor_methods},
     {Py_tp_new, Compressor_new},
     {Py_tp_doc, (char *)Compressor_doc},
-    {Py_tp_traverse, Compressor_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 
@@ -1328,13 +1321,6 @@ Decompressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
-static int
-Decompressor_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyMethodDef Decompressor_methods[] = {
     _LZMA_LZMADECOMPRESSOR_DECOMPRESS_METHODDEF
     {NULL}
@@ -1369,7 +1355,7 @@ static PyType_Slot lzma_decompressor_type_slots[] = {
     {Py_tp_methods, Decompressor_methods},
     {Py_tp_new, _lzma_LZMADecompressor},
     {Py_tp_doc, (char *)_lzma_LZMADecompressor__doc__},
-    {Py_tp_traverse, Decompressor_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_members, Decompressor_members},
     {0, 0}
 };
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index bc06478799345a..0774e91039ec41 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -413,13 +413,6 @@ typedef struct {
 
 #define Pdata_CAST(op)  ((Pdata *)(op))
 
-static int
-Pdata_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 Pdata_dealloc(PyObject *op)
 {
@@ -437,7 +430,7 @@ Pdata_dealloc(PyObject *op)
 
 static PyType_Slot pdata_slots[] = {
     {Py_tp_dealloc, Pdata_dealloc},
-    {Py_tp_traverse, Pdata_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, NULL},
 };
 
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 2388bbb3bae631..048e640283638b 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -5692,13 +5692,6 @@ _ssl_MemoryBIO_impl(PyTypeObject *type)
     return (PyObject *) self;
 }
 
-static int
-memory_bio_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 memory_bio_dealloc(PyObject *op)
 {
@@ -5869,7 +5862,7 @@ static PyType_Slot PySSLMemoryBIO_slots[] = {
     {Py_tp_getset, memory_bio_getsetlist},
     {Py_tp_new, _ssl_MemoryBIO},
     {Py_tp_dealloc, memory_bio_dealloc},
-    {Py_tp_traverse, memory_bio_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0},
 };
 

From 55c530c3791e8acf58d00c5dc5bfa11bf9a5206d Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:10:00 -0400
Subject: [PATCH 05/17] Use it in _thread.

---
 Modules/_threadmodule.c | 27 +++------------------------
 1 file changed, 3 insertions(+), 24 deletions(-)

diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index 0a22907375b0dd..1a64289ea01fdb 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -655,13 +655,6 @@ PyThreadHandleObject_tp_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     return (PyObject *)PyThreadHandleObject_new(type);
 }
 
-static int
-PyThreadHandleObject_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 PyThreadHandleObject_dealloc(PyObject *op)
 {
@@ -751,7 +744,7 @@ static PyType_Slot ThreadHandle_Type_slots[] = {
     {Py_tp_dealloc, PyThreadHandleObject_dealloc},
     {Py_tp_repr, PyThreadHandleObject_repr},
     {Py_tp_getset, ThreadHandle_getsetlist},
-    {Py_tp_traverse, PyThreadHandleObject_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_methods, ThreadHandle_methods},
     {Py_tp_new, PyThreadHandleObject_tp_new},
     {0, 0}
@@ -767,13 +760,6 @@ static PyType_Spec ThreadHandle_Type_spec = {
 
 /* Lock objects */
 
-static int
-lock_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 lock_dealloc(PyObject *self)
 {
@@ -1045,7 +1031,7 @@ static PyType_Slot lock_type_slots[] = {
     {Py_tp_repr, lock_repr},
     {Py_tp_doc, (void *)lock_doc},
     {Py_tp_methods, lock_methods},
-    {Py_tp_traverse, lock_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_new, lock_new},
     {0, 0}
 };
@@ -1060,13 +1046,6 @@ static PyType_Spec lock_type_spec = {
 
 /* Recursive lock objects */
 
-static int
-rlock_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static int
 rlock_locked_impl(rlockobject *self)
 {
@@ -1359,7 +1338,7 @@ static PyType_Slot rlock_type_slots[] = {
     {Py_tp_methods, rlock_methods},
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_new, rlock_new},
-    {Py_tp_traverse, rlock_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0},
 };
 

From 21b3024964802ed6afa8958d2026843c75fe2af8 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:11:47 -0400
Subject: [PATCH 06/17] Use it in array, blake2, hmac, and md5.

---
 Modules/arraymodule.c  |  9 +--------
 Modules/blake2module.c | 11 ++---------
 Modules/hmacmodule.c   |  9 +--------
 Modules/md5module.c    |  8 +-------
 4 files changed, 5 insertions(+), 32 deletions(-)

diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 654e9445985d84..e2c239d1f8b285 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -715,13 +715,6 @@ ins1(arrayobject *self, Py_ssize_t where, PyObject *v)
 
 /* Methods */
 
-static int
-array_tp_traverse(PyObject *op, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(op));
-    return 0;
-}
-
 static void
 array_dealloc(PyObject *op)
 {
@@ -2968,7 +2961,7 @@ static PyType_Slot array_slots[] = {
     {Py_tp_getset, array_getsets},
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_new, array_new},
-    {Py_tp_traverse, array_tp_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
 
     /* as sequence */
     {Py_sq_length, array_length},
diff --git a/Modules/blake2module.c b/Modules/blake2module.c
index 163f238a4268d0..4921e8f945ef37 100644
--- a/Modules/blake2module.c
+++ b/Modules/blake2module.c
@@ -1008,17 +1008,10 @@ py_blake2_dealloc(PyObject *self)
     Py_DECREF(type);
 }
 
-static int
-py_blake2_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyType_Slot blake2b_type_slots[] = {
     {Py_tp_clear, py_blake2_clear},
     {Py_tp_dealloc, py_blake2_dealloc},
-    {Py_tp_traverse, py_blake2_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_doc, (char *)py_blake2b_new__doc__},
     {Py_tp_methods, py_blake2b_methods},
     {Py_tp_getset, py_blake2b_getsetters},
@@ -1029,7 +1022,7 @@ static PyType_Slot blake2b_type_slots[] = {
 static PyType_Slot blake2s_type_slots[] = {
     {Py_tp_clear, py_blake2_clear},
     {Py_tp_dealloc, py_blake2_dealloc},
-    {Py_tp_traverse, py_blake2_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_doc, (char *)py_blake2s_new__doc__},
     {Py_tp_methods, py_blake2b_methods},
     {Py_tp_getset, py_blake2b_getsetters},
diff --git a/Modules/hmacmodule.c b/Modules/hmacmodule.c
index 680c93a04cac17..b30dda501a0716 100644
--- a/Modules/hmacmodule.c
+++ b/Modules/hmacmodule.c
@@ -1032,13 +1032,6 @@ HMACObject_dealloc(PyObject *op)
     Py_DECREF(type);
 }
 
-static int
-HMACObject_traverse(PyObject *op, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(op));
-    return 0;
-}
-
 static PyMethodDef HMACObject_methods[] = {
     _HMAC_HMAC_COPY_METHODDEF
     _HMAC_HMAC_UPDATE_METHODDEF
@@ -1060,7 +1053,7 @@ static PyType_Slot HMACObject_Type_slots[] = {
     {Py_tp_getset, HMACObject_getsets},
     {Py_tp_clear, HMACObject_clear},
     {Py_tp_dealloc, HMACObject_dealloc},
-    {Py_tp_traverse, HMACObject_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, NULL} /* sentinel */
 };
 
diff --git a/Modules/md5module.c b/Modules/md5module.c
index 8b6dd4a8195dfb..7b3902483bbfcb 100644
--- a/Modules/md5module.c
+++ b/Modules/md5module.c
@@ -82,12 +82,6 @@ newMD5object(MD5State * st)
 }
 
 /* Internal methods for a hash object */
-static int
-MD5_traverse(PyObject *ptr, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(ptr));
-    return 0;
-}
 
 static void
 MD5_dealloc(PyObject *op)
@@ -246,7 +240,7 @@ static PyType_Slot md5_type_slots[] = {
     {Py_tp_dealloc, MD5_dealloc},
     {Py_tp_methods, MD5_methods},
     {Py_tp_getset, MD5_getseters},
-    {Py_tp_traverse, MD5_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0,0}
 };
 

From d8ea9e023c3c84f385ec0f40c94240dd16eb0ba0 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:12:47 -0400
Subject: [PATCH 07/17] Use it in mmap, sha1, sha2, and sha3.

---
 Modules/mmapmodule.c |  9 +--------
 Modules/sha1module.c |  8 +-------
 Modules/sha2module.c | 11 ++---------
 Modules/sha3module.c |  9 +--------
 4 files changed, 5 insertions(+), 32 deletions(-)

diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 0cb4b62d734550..8413ebe668dffe 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -128,13 +128,6 @@ typedef struct {
 
 #define mmap_object_CAST(op)    ((mmap_object *)(op))
 
-static int
-mmap_object_traverse(PyObject *op, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(op));
-    return 0;
-}
-
 static void
 mmap_object_dealloc(PyObject *op)
 {
@@ -1499,7 +1492,7 @@ static PyType_Slot mmap_object_slots[] = {
     {Py_tp_members, mmap_object_members},
     {Py_tp_getset, mmap_object_getset},
     {Py_tp_getattro, PyObject_GenericGetAttr},
-    {Py_tp_traverse, mmap_object_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
 
     /* as sequence */
     {Py_sq_length, mmap_length},
diff --git a/Modules/sha1module.c b/Modules/sha1module.c
index faa9dcccc5755b..289372371e45a8 100644
--- a/Modules/sha1module.c
+++ b/Modules/sha1module.c
@@ -81,12 +81,6 @@ newSHA1object(SHA1State *st)
 
 
 /* Internal methods for a hash object */
-static int
-SHA1_traverse(PyObject *ptr, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(ptr));
-    return 0;
-}
 
 static void
 SHA1_dealloc(PyObject *op)
@@ -247,7 +241,7 @@ static PyType_Slot sha1_type_slots[] = {
     {Py_tp_dealloc, SHA1_dealloc},
     {Py_tp_methods, SHA1_methods},
     {Py_tp_getset, SHA1_getseters},
-    {Py_tp_traverse, SHA1_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0,0}
 };
 
diff --git a/Modules/sha2module.c b/Modules/sha2module.c
index 36300ba899fd44..f8408eec5b2989 100644
--- a/Modules/sha2module.c
+++ b/Modules/sha2module.c
@@ -165,13 +165,6 @@ newSHA512object(sha2_state *state)
 
 /* Internal methods for our hash objects. */
 
-static int
-SHA2_traverse(PyObject *ptr, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(ptr));
-    return 0;
-}
-
 static void
 SHA256_dealloc(PyObject *op)
 {
@@ -519,7 +512,7 @@ static PyType_Slot sha256_types_slots[] = {
     {Py_tp_dealloc, SHA256_dealloc},
     {Py_tp_methods, SHA256_methods},
     {Py_tp_getset, SHA256_getseters},
-    {Py_tp_traverse, SHA2_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0,0}
 };
 
@@ -527,7 +520,7 @@ static PyType_Slot sha512_type_slots[] = {
     {Py_tp_dealloc, SHA512_dealloc},
     {Py_tp_methods, SHA512_methods},
     {Py_tp_getset, SHA512_getseters},
-    {Py_tp_traverse, SHA2_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0,0}
 };
 
diff --git a/Modules/sha3module.c b/Modules/sha3module.c
index 5764556bb680f3..de4bf09b8e7e0b 100644
--- a/Modules/sha3module.c
+++ b/Modules/sha3module.c
@@ -226,13 +226,6 @@ SHA3_dealloc(PyObject *self)
     Py_DECREF(tp);
 }
 
-static int
-SHA3_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 /* External methods for a hash object */
 
 
@@ -424,7 +417,7 @@ static PyGetSetDef SHA3_getseters[] = {
     static PyType_Slot type_slots_obj[] = { \
         {Py_tp_clear, SHA3_clear}, \
         {Py_tp_dealloc, SHA3_dealloc}, \
-        {Py_tp_traverse, SHA3_traverse}, \
+        {Py_tp_traverse, _PyObject_VisitType}, \
         {Py_tp_doc, (char*)type_doc}, \
         {Py_tp_methods, type_methods}, \
         {Py_tp_getset, type_getseters}, \

From 0cb7f4cc0a8abf6bf1ded1f54059f0205051a9b6 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:13:15 -0400
Subject: [PATCH 08/17] Use it in socket and unicodedata.

---
 Modules/socketmodule.c | 9 +--------
 Modules/unicodedata.c  | 9 +--------
 2 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index c5b16dc4fe4c5f..dc8e08ac3e522e 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -5538,13 +5538,6 @@ sock_finalize(PyObject *self)
     PyErr_SetRaisedException(exc);
 }
 
-static int
-sock_traverse(PyObject *s, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(s));
-    return 0;
-}
-
 static void
 sock_dealloc(PyObject *s)
 {
@@ -5843,7 +5836,7 @@ sock_initobj_impl(PySocketSockObject *self, int family, int type, int proto,
 
 static PyType_Slot sock_slots[] = {
     {Py_tp_dealloc, sock_dealloc},
-    {Py_tp_traverse, sock_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_repr, sock_repr},
     {Py_tp_doc, (void *)sock_doc},
     {Py_tp_methods, sock_methods},
diff --git a/Modules/unicodedata.c b/Modules/unicodedata.c
index 2a30030a2a1153..41725e5aec1641 100644
--- a/Modules/unicodedata.c
+++ b/Modules/unicodedata.c
@@ -1594,13 +1594,6 @@ static PyMethodDef unicodedata_functions[] = {
     {NULL, NULL}                /* sentinel */
 };
 
-static int
-ucd_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 ucd_dealloc(PyObject *self)
 {
@@ -1612,7 +1605,7 @@ ucd_dealloc(PyObject *self)
 
 static PyType_Slot ucd_type_slots[] = {
     {Py_tp_dealloc, ucd_dealloc},
-    {Py_tp_traverse, ucd_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_getattro, PyObject_GenericGetAttr},
     {Py_tp_methods, unicodedata_functions},
     {Py_tp_members, DB_members},

From a05d9d083734cdef6aa49ae45b0fdf05d1b3747c Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:13:52 -0400
Subject: [PATCH 09/17] Use it in _decimal.

---
 Modules/_decimal/_decimal.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index de7200af8c158b..50994be2968d35 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -746,13 +746,6 @@ signaldict_setitem(PyObject *self, PyObject *key, PyObject *value)
     return 0;
 }
 
-static int
-signaldict_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 signaldict_dealloc(PyObject *self)
 {
@@ -845,7 +838,7 @@ static PyMethodDef signaldict_methods[] = {
 
 static PyType_Slot signaldict_slots[] = {
     {Py_tp_dealloc, signaldict_dealloc},
-    {Py_tp_traverse, signaldict_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_repr, signaldict_repr},
     {Py_tp_hash, PyObject_HashNotImplemented},
     {Py_tp_getattro, PyObject_GenericGetAttr},
@@ -2194,13 +2187,6 @@ PyDecType_New(decimal_state *state, PyTypeObject *type)
 }
 #define dec_alloc(st) PyDecType_New(st, (st)->PyDec_Type)
 
-static int
-dec_traverse(PyObject *dec, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(dec));
-    return 0;
-}
-
 static void
 dec_dealloc(PyObject *dec)
 {
@@ -6032,7 +6018,7 @@ static PyType_Slot dec_slots[] = {
     {Py_tp_token, Py_TP_USE_SPEC},
     {Py_tp_dealloc, dec_dealloc},
     {Py_tp_getattro, PyObject_GenericGetAttr},
-    {Py_tp_traverse, dec_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_repr, dec_repr},
     {Py_tp_hash, dec_hash},
     {Py_tp_str, dec_str},

From e86e0d6655d5040310af6ee70ca7f59f539d7b5e Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:14:33 -0400
Subject: [PATCH 10/17] Use it in _multiprocessing and _sqlite.

---
 Modules/_multiprocessing/semaphore.c | 9 +--------
 Modules/_sqlite/prepare_protocol.c   | 9 +--------
 Modules/_sqlite/statement.c          | 9 +--------
 3 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/Modules/_multiprocessing/semaphore.c b/Modules/_multiprocessing/semaphore.c
index a4a2a866ccbfce..d5a1f27e9ff4ff 100644
--- a/Modules/_multiprocessing/semaphore.c
+++ b/Modules/_multiprocessing/semaphore.c
@@ -720,13 +720,6 @@ _multiprocessing_SemLock___exit___impl(SemLockObject *self,
     return _multiprocessing_SemLock_release_impl(self);
 }
 
-static int
-semlock_traverse(PyObject *s, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(s));
-    return 0;
-}
-
 /*
  * Semaphore methods
  */
@@ -773,7 +766,7 @@ static PyType_Slot _PyMp_SemLockType_slots[] = {
     {Py_tp_members, semlock_members},
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_new, _multiprocessing_SemLock},
-    {Py_tp_traverse, semlock_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_free, PyObject_GC_Del},
     {Py_tp_doc, (void *)PyDoc_STR("Semaphore/Mutex type")},
     {0, 0},
diff --git a/Modules/_sqlite/prepare_protocol.c b/Modules/_sqlite/prepare_protocol.c
index 31092417cb480d..d7ac09e3947a77 100644
--- a/Modules/_sqlite/prepare_protocol.c
+++ b/Modules/_sqlite/prepare_protocol.c
@@ -29,13 +29,6 @@ pysqlite_prepare_protocol_init(PyObject *self, PyObject *args, PyObject *kwargs)
     return 0;
 }
 
-static int
-pysqlite_prepare_protocol_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static void
 pysqlite_prepare_protocol_dealloc(PyObject *self)
 {
@@ -50,7 +43,7 @@ PyDoc_STRVAR(doc, "PEP 246 style object adaption protocol type.");
 static PyType_Slot type_slots[] = {
     {Py_tp_dealloc, pysqlite_prepare_protocol_dealloc},
     {Py_tp_init, pysqlite_prepare_protocol_init},
-    {Py_tp_traverse, pysqlite_prepare_protocol_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_doc, (void *)doc},
     {0, NULL},
 };
diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index 736e60fd778287..77181104eda10b 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -116,13 +116,6 @@ stmt_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
-static int
-stmt_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 /*
  * Strip leading whitespace and comments from incoming SQL (null terminated C
  * string) and return a pointer to the first non-whitespace, non-comment
@@ -183,7 +176,7 @@ lstrip_sql(const char *sql)
 
 static PyType_Slot stmt_slots[] = {
     {Py_tp_dealloc, stmt_dealloc},
-    {Py_tp_traverse, stmt_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, NULL},
 };
 

From 68f0b412b619be0e92c31f3576ffbc949be2a453 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:15:23 -0400
Subject: [PATCH 11/17] Use it in the remaining files.

---
 Objects/typevarobject.c | 9 +--------
 PC/winreg.c             | 9 +--------
 2 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/Objects/typevarobject.c b/Objects/typevarobject.c
index cead6e69af5451..522e9fd9c955af 100644
--- a/Objects/typevarobject.c
+++ b/Objects/typevarobject.c
@@ -2304,20 +2304,13 @@ generic_dealloc(PyObject *self)
     Py_DECREF(tp);
 }
 
-static int
-generic_traverse(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static PyType_Slot generic_slots[] = {
     {Py_tp_doc, (void *)generic_doc},
     {Py_tp_methods, generic_methods},
     {Py_tp_dealloc, generic_dealloc},
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_free, PyObject_GC_Del},
-    {Py_tp_traverse, generic_traverse},
+    {Py_tp_traverse, _PyObject_VisitType},
     {0, NULL},
 };
 
diff --git a/PC/winreg.c b/PC/winreg.c
index 05a33006c32326..9bbacb0f50bd63 100644
--- a/PC/winreg.c
+++ b/PC/winreg.c
@@ -161,13 +161,6 @@ PyHKEY_deallocFunc(PyObject *ob)
     Py_DECREF(tp);
 }
 
-static int
-PyHKEY_traverseFunc(PyObject *self, visitproc visit, void *arg)
-{
-    Py_VISIT(Py_TYPE(self));
-    return 0;
-}
-
 static int
 PyHKEY_boolFunc(PyObject *ob)
 {
@@ -369,7 +362,7 @@ static PyType_Slot pyhkey_type_slots[] = {
     {Py_tp_members, PyHKEY_memberlist},
     {Py_tp_methods, PyHKEY_methods},
     {Py_tp_doc, (char *)PyHKEY_doc},
-    {Py_tp_traverse, PyHKEY_traverseFunc},
+    {Py_tp_traverse, _PyObject_VisitType},
     {Py_tp_hash, PyHKEY_hashFunc},
     {Py_tp_str, PyHKEY_strFunc},
 

From c58e4d0c117cc6ee47de9b7e465d411fc5076791 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:19:18 -0400
Subject: [PATCH 12/17] Add some more assertions to _PyObject_VisitType.

---
 Objects/object.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Objects/object.c b/Objects/object.c
index c8dc7acecea0bd..e2e29500d558e4 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -3388,6 +3388,9 @@ PyUnstable_Object_IsUniquelyReferenced(PyObject *op)
 int _PyObject_VisitType(PyObject *op, visitproc visit, void *arg)
 {
     assert(op != NULL);
-    Py_VISIT(Py_TYPE(op));
+    PyTypeObject *tp = Py_TYPE(op);
+    assert(PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE));
+    assert(!PyType_HasFeature(tp, Py_TPFLAGS_IMMUTABLETYPE));
+    Py_VISIT(tp);
     return 0;
 }

From bb72a79333a06728cc6c466b6ce6bb46e4ee2863 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:24:17 -0400
Subject: [PATCH 13/17] Relax assertion.

---
 Objects/object.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Objects/object.c b/Objects/object.c
index e2e29500d558e4..90630f16a57c6e 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -3389,8 +3389,7 @@ int _PyObject_VisitType(PyObject *op, visitproc visit, void *arg)
 {
     assert(op != NULL);
     PyTypeObject *tp = Py_TYPE(op);
-    assert(PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE));
-    assert(!PyType_HasFeature(tp, Py_TPFLAGS_IMMUTABLETYPE));
+    _PyObject_ASSERT((PyObject *)tp, PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE));
     Py_VISIT(tp);
     return 0;
 }

From be0abd98b8fb5930300bd09cfefe261bc7991c08 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 10:52:54 -0400
Subject: [PATCH 14/17] Formatting.

---
 Objects/object.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Objects/object.c b/Objects/object.c
index 90630f16a57c6e..bd3ba02f8eb255 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -3385,7 +3385,8 @@ PyUnstable_Object_IsUniquelyReferenced(PyObject *op)
     return _PyObject_IsUniquelyReferenced(op);
 }
 
-int _PyObject_VisitType(PyObject *op, visitproc visit, void *arg)
+int
+_PyObject_VisitType(PyObject *op, visitproc visit, void *arg)
 {
     assert(op != NULL);
     PyTypeObject *tp = Py_TYPE(op);

From 6ae2f1d802764b2452e8b40c5a2e2d4675a904d5 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 11:42:14 -0400
Subject: [PATCH 15/17] Fix whitespace.

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
---
 Modules/_gdbmmodule.c | 1 -
 Modules/arraymodule.c | 1 -
 Modules/md5module.c   | 1 -
 Modules/sha1module.c  | 1 -
 Modules/sha2module.c  | 1 -
 5 files changed, 5 deletions(-)

diff --git a/Modules/_gdbmmodule.c b/Modules/_gdbmmodule.c
index 87f62b945b2923..7bef6ae7f0c43e 100644
--- a/Modules/_gdbmmodule.c
+++ b/Modules/_gdbmmodule.c
@@ -122,7 +122,6 @@ newgdbmobject(_gdbm_state *state, const char *file, int flags, int mode)
 }
 
 /* Methods */
-
 static void
 gdbm_dealloc(PyObject *op)
 {
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index e2c239d1f8b285..d9ac5b97f8258f 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -714,7 +714,6 @@ ins1(arrayobject *self, Py_ssize_t where, PyObject *v)
 }
 
 /* Methods */
-
 static void
 array_dealloc(PyObject *op)
 {
diff --git a/Modules/md5module.c b/Modules/md5module.c
index 7b3902483bbfcb..6b6457427b6b5e 100644
--- a/Modules/md5module.c
+++ b/Modules/md5module.c
@@ -82,7 +82,6 @@ newMD5object(MD5State * st)
 }
 
 /* Internal methods for a hash object */
-
 static void
 MD5_dealloc(PyObject *op)
 {
diff --git a/Modules/sha1module.c b/Modules/sha1module.c
index 289372371e45a8..d64eb91458cae8 100644
--- a/Modules/sha1module.c
+++ b/Modules/sha1module.c
@@ -81,7 +81,6 @@ newSHA1object(SHA1State *st)
 
 
 /* Internal methods for a hash object */
-
 static void
 SHA1_dealloc(PyObject *op)
 {
diff --git a/Modules/sha2module.c b/Modules/sha2module.c
index f8408eec5b2989..66259fe47a0fd3 100644
--- a/Modules/sha2module.c
+++ b/Modules/sha2module.c
@@ -164,7 +164,6 @@ newSHA512object(sha2_state *state)
 }
 
 /* Internal methods for our hash objects. */
-
 static void
 SHA256_dealloc(PyObject *op)
 {

From 74eb905f0d2f585eb6ece21b6df66e1830464ec6 Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 11:45:16 -0400
Subject: [PATCH 16/17] Remove changes that will be reverted.

---
 Modules/_bz2module.c  | 1 -
 Modules/_lzmamodule.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 73c5546af60b64..507bdb52d42411 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -402,7 +402,6 @@ static PyType_Slot bz2_compressor_type_slots[] = {
     {Py_tp_methods, BZ2Compressor_methods},
     {Py_tp_new, _bz2_BZ2Compressor},
     {Py_tp_doc, (char *)_bz2_BZ2Compressor__doc__},
-    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
index 30a42ccb0082b8..f7360fe897c03e 100644
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -915,7 +915,6 @@ static PyType_Slot lzma_compressor_type_slots[] = {
     {Py_tp_methods, Compressor_methods},
     {Py_tp_new, Compressor_new},
     {Py_tp_doc, (char *)Compressor_doc},
-    {Py_tp_traverse, _PyObject_VisitType},
     {0, 0}
 };
 

From 1b03df5dfee1dc7e84ccd622556e1f69b8deb4aa Mon Sep 17 00:00:00 2001
From: Peter Bierma <zintensitydev@gmail.com>
Date: Mon, 1 Sep 2025 11:51:20 -0400
Subject: [PATCH 17/17] Remove changes to existing code.

---
 Modules/_bz2module.c  | 17 ++++++++++++++++-
 Modules/_lzmamodule.c | 17 ++++++++++++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 507bdb52d42411..914172684158a1 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -391,6 +391,13 @@ BZ2Compressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
+static int
+BZ2Compressor_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
 static PyMethodDef BZ2Compressor_methods[] = {
     _BZ2_BZ2COMPRESSOR_COMPRESS_METHODDEF
     _BZ2_BZ2COMPRESSOR_FLUSH_METHODDEF
@@ -402,6 +409,7 @@ static PyType_Slot bz2_compressor_type_slots[] = {
     {Py_tp_methods, BZ2Compressor_methods},
     {Py_tp_new, _bz2_BZ2Compressor},
     {Py_tp_doc, (char *)_bz2_BZ2Compressor__doc__},
+    {Py_tp_traverse, BZ2Compressor_traverse},
     {0, 0}
 };
 
@@ -695,6 +703,13 @@ BZ2Decompressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
+static int
+BZ2Decompressor_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
 static PyMethodDef BZ2Decompressor_methods[] = {
     _BZ2_BZ2DECOMPRESSOR_DECOMPRESS_METHODDEF
     {NULL}
@@ -725,7 +740,7 @@ static PyType_Slot bz2_decompressor_type_slots[] = {
     {Py_tp_doc, (char *)_bz2_BZ2Decompressor__doc__},
     {Py_tp_members, BZ2Decompressor_members},
     {Py_tp_new, _bz2_BZ2Decompressor},
-    {Py_tp_traverse, _PyObject_VisitType},
+    {Py_tp_traverse, BZ2Decompressor_traverse},
     {0, 0}
 };
 
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
index f7360fe897c03e..0b0b1bc765bbc9 100644
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -882,6 +882,13 @@ static PyMethodDef Compressor_methods[] = {
     {NULL}
 };
 
+static int
+Compressor_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
 PyDoc_STRVAR(Compressor_doc,
 "LZMACompressor(format=FORMAT_XZ, check=-1, preset=None, filters=None)\n"
 "\n"
@@ -915,6 +922,7 @@ static PyType_Slot lzma_compressor_type_slots[] = {
     {Py_tp_methods, Compressor_methods},
     {Py_tp_new, Compressor_new},
     {Py_tp_doc, (char *)Compressor_doc},
+    {Py_tp_traverse, Compressor_traverse},
     {0, 0}
 };
 
@@ -1320,6 +1328,13 @@ Decompressor_dealloc(PyObject *op)
     Py_DECREF(tp);
 }
 
+static int
+Decompressor_traverse(PyObject *self, visitproc visit, void *arg)
+{
+    Py_VISIT(Py_TYPE(self));
+    return 0;
+}
+
 static PyMethodDef Decompressor_methods[] = {
     _LZMA_LZMADECOMPRESSOR_DECOMPRESS_METHODDEF
     {NULL}
@@ -1354,7 +1369,7 @@ static PyType_Slot lzma_decompressor_type_slots[] = {
     {Py_tp_methods, Decompressor_methods},
     {Py_tp_new, _lzma_LZMADecompressor},
     {Py_tp_doc, (char *)_lzma_LZMADecompressor__doc__},
-    {Py_tp_traverse, _PyObject_VisitType},
+    {Py_tp_traverse, Decompressor_traverse},
     {Py_tp_members, Decompressor_members},
     {0, 0}
 };