From f1ef66137f80b1238e3ac2914290163dda802922 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 00:15:49 +0800
Subject: [PATCH 01/12] Do not reset tp_version_tag

---
 Include/internal/pycore_object.h |  2 ++
 Lib/test/test_type_cache.py      | 41 ++++++++++++++++++++++++++++++++
 Objects/typeobject.c             | 16 +++++++++----
 Python/clinic/sysmodule.c.h      | 19 ++++++++++++++-
 Python/sysmodule.c               | 35 ++++++++++++++++++++++++++-
 5 files changed, 106 insertions(+), 7 deletions(-)
 create mode 100644 Lib/test/test_type_cache.py

diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 744b41ae5d90d6..16e95fbf971ec3 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -182,6 +182,8 @@ extern PyObject* _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems);
 
 extern int _PyObject_InitializeDict(PyObject *obj);
 
+extern unsigned int _PyType_ClearCache_NoResetGlobalVersionTag(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
new file mode 100644
index 00000000000000..638232bcec0c22
--- /dev/null
+++ b/Lib/test/test_type_cache.py
@@ -0,0 +1,41 @@
+""" Tests for the internal type cache in CPython. """
+import unittest
+from collections import Counter
+from test import support
+try:
+    from sys import _clear_type_cache, _get_type_version_tag
+except ImportError:
+    _clear_type_cache = None
+
+msg = "requires sys._clear_type_cache and sys._get_type_version_tag"
+@unittest.skipIf(_clear_type_cache is None, msg)
+@support.cpython_only
+class TypeCacheTests(unittest.TestCase):
+    def test_tp_version_tag_unique(self):
+        """tp_version_tag should be unique assuming no overflow, even after
+        clearing type cache.
+        """
+        all_version_tags = []
+        append_result = all_version_tags.append
+        # Note: try to avoid any method lookups within this loop,
+        # It will affect global version tag.
+        for _ in range(30):
+            _clear_type_cache()
+            class C:
+                # __init__ is only here to force
+                # C.tp_version_tag to update when initializing
+                # object C().
+                def __init__(self):
+                    pass
+            x = C()
+            tp_version_tag_after = _get_type_version_tag(C)
+            # Try to avoid self.assertNotEqual to not overflow type cache.
+            assert tp_version_tag_after != 0
+            append_result(tp_version_tag_after)
+        tp_version_tag, count = Counter(all_version_tags).most_common(1)[0]
+        self.assertEqual(count, 1,
+                         msg=f"tp_version_tag {tp_version_tag} was not unique")
+
+
+if __name__ == "__main__":
+    support.run_unittest(TypeCacheTests)
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 7ae50c453ed2f8..7087dc5e8097db 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -272,7 +272,7 @@ _PyType_InitCache(PyInterpreterState *interp)
 
 
 static unsigned int
-_PyType_ClearCache(PyInterpreterState *interp)
+_PyType_ClearCache(PyInterpreterState *interp, int reset_global_version_tag)
 {
     struct type_cache *cache = &interp->type_cache;
 #if MCACHE_STATS
@@ -288,7 +288,7 @@ _PyType_ClearCache(PyInterpreterState *interp)
 #endif
 
     unsigned int cur_version_tag = next_version_tag - 1;
-    if (_Py_IsMainInterpreter(interp)) {
+    if (reset_global_version_tag && _Py_IsMainInterpreter(interp)) {
         next_version_tag = 0;
     }
 
@@ -302,14 +302,20 @@ unsigned int
 PyType_ClearCache(void)
 {
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    return _PyType_ClearCache(interp);
+    return _PyType_ClearCache(interp, 1);
 }
 
+unsigned int
+_PyType_ClearCache_NoResetGlobalVersionTag(void)
+{
+    PyInterpreterState *interp = _PyInterpreterState_GET();
+    return _PyType_ClearCache(interp, 1);
+}
 
 void
 _PyType_Fini(PyInterpreterState *interp)
 {
-    _PyType_ClearCache(interp);
+    _PyType_ClearCache(interp, 1);
     if (_Py_IsMainInterpreter(interp)) {
         clear_slotdefs();
     }
@@ -3853,7 +3859,7 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
         }
 #endif
         assert(_PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG));
-        Py_SETREF(entry->name, Py_NewRef(name));
+        Py_XSETREF(entry->name, Py_NewRef(name));
     }
     return res;
 }
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 8350fbf98561a9..8e0c558acc5ed7 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -925,6 +925,19 @@ sys__clear_type_cache(PyObject *module, PyObject *Py_UNUSED(ignored))
     return sys__clear_type_cache_impl(module);
 }
 
+#if defined(Py_DEBUG)
+
+PyDoc_STRVAR(sys__get_type_version_tag__doc__,
+"_get_type_version_tag($module, type, /)\n"
+"--\n"
+"\n"
+"For internal use only: get the `tp_version_tag` of *type*.");
+
+#define SYS__GET_TYPE_VERSION_TAG_METHODDEF    \
+    {"_get_type_version_tag", (PyCFunction)sys__get_type_version_tag, METH_O, sys__get_type_version_tag__doc__},
+
+#endif /* defined(Py_DEBUG) */
+
 PyDoc_STRVAR(sys_is_finalizing__doc__,
 "is_finalizing($module, /)\n"
 "--\n"
@@ -989,7 +1002,11 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
     #define SYS_GETTOTALREFCOUNT_METHODDEF
 #endif /* !defined(SYS_GETTOTALREFCOUNT_METHODDEF) */
 
+#ifndef SYS__GET_TYPE_VERSION_TAG_METHODDEF
+    #define SYS__GET_TYPE_VERSION_TAG_METHODDEF
+#endif /* !defined(SYS__GET_TYPE_VERSION_TAG_METHODDEF) */
+
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=855fc93b2347710b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=8e0a9df4ee406dcb input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 5dfa917e8ffb20..b367c5e867db9b 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1937,10 +1937,42 @@ static PyObject *
 sys__clear_type_cache_impl(PyObject *module)
 /*[clinic end generated code: output=20e48ca54a6f6971 input=127f3e04a8d9b555]*/
 {
-    PyType_ClearCache();
+    // Don't reset the global tp_version_tag. It causes version tag resuse and
+    // cache inconsistencies.
+    _PyType_ClearCache_NoResetGlobalVersionTag();
     Py_RETURN_NONE;
 }
 
+#ifdef Py_DEBUG
+/*[clinic input]
+sys._get_type_version_tag
+
+    type: object
+    /
+
+For internal use only: get the `tp_version_tag` of *type*.
+[clinic start generated code]*/
+
+static PyObject *
+sys__get_type_version_tag(PyObject *module, PyObject *type)
+/*[clinic end generated code: output=bdcfab8b295e0a76 input=6016e5a02b3c3675]*/
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    _Py_EnsureTstateNotNULL(tstate);
+
+    if (!PyType_Check(type)) {
+        _PyErr_SetString(tstate, PyExc_TypeError, "argument must be a type");
+        return NULL;
+    }
+    PyObject *res = PyLong_FromUnsignedLong(((PyTypeObject *)type)->tp_version_tag);
+    if (res == NULL) {
+        assert(_PyErr_Occurred(tstate));
+        return NULL;
+    }
+    return res;
+}
+#endif /* Py_DEBUG */
+
 /*[clinic input]
 sys.is_finalizing
 
@@ -1976,6 +2008,7 @@ static PyMethodDef sys_methods[] = {
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
     SYS__CLEAR_TYPE_CACHE_METHODDEF
+    SYS__GET_TYPE_VERSION_TAG_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF
     SYS__CURRENT_EXCEPTIONS_METHODDEF
     SYS_DISPLAYHOOK_METHODDEF

From 3a99d64a7fedfc8bd69e7f869234c2727410d104 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 20:30:57 +0800
Subject: [PATCH 02/12] revert changes to typeobject, add test to test_sys

---
 Include/internal/pycore_object.h |  2 --
 Lib/test/test_sys.py             |  5 +++++
 Objects/typeobject.c             | 16 +++++-----------
 3 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 16e95fbf971ec3..744b41ae5d90d6 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -182,8 +182,6 @@ extern PyObject* _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems);
 
 extern int _PyObject_InitializeDict(PyObject *obj);
 
-extern unsigned int _PyType_ClearCache_NoResetGlobalVersionTag(void);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index dba4928ec261ac..3b645fbaa17e01 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -628,6 +628,11 @@ def test_sys_getwindowsversion_no_instantiation(self):
     def test_clear_type_cache(self):
         sys._clear_type_cache()
 
+    @test.support.cpython_only
+    def test_get_type_version_tag(self):
+        test.support.get_attribute(sys, "_get_type_version_tag")
+        self.assertIsInstance(sys._get_type_version_tag(int), int)
+
     def test_ioencoding(self):
         env = dict(os.environ)
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 7087dc5e8097db..7ae50c453ed2f8 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -272,7 +272,7 @@ _PyType_InitCache(PyInterpreterState *interp)
 
 
 static unsigned int
-_PyType_ClearCache(PyInterpreterState *interp, int reset_global_version_tag)
+_PyType_ClearCache(PyInterpreterState *interp)
 {
     struct type_cache *cache = &interp->type_cache;
 #if MCACHE_STATS
@@ -288,7 +288,7 @@ _PyType_ClearCache(PyInterpreterState *interp, int reset_global_version_tag)
 #endif
 
     unsigned int cur_version_tag = next_version_tag - 1;
-    if (reset_global_version_tag && _Py_IsMainInterpreter(interp)) {
+    if (_Py_IsMainInterpreter(interp)) {
         next_version_tag = 0;
     }
 
@@ -302,20 +302,14 @@ unsigned int
 PyType_ClearCache(void)
 {
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    return _PyType_ClearCache(interp, 1);
+    return _PyType_ClearCache(interp);
 }
 
-unsigned int
-_PyType_ClearCache_NoResetGlobalVersionTag(void)
-{
-    PyInterpreterState *interp = _PyInterpreterState_GET();
-    return _PyType_ClearCache(interp, 1);
-}
 
 void
 _PyType_Fini(PyInterpreterState *interp)
 {
-    _PyType_ClearCache(interp, 1);
+    _PyType_ClearCache(interp);
     if (_Py_IsMainInterpreter(interp)) {
         clear_slotdefs();
     }
@@ -3859,7 +3853,7 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
         }
 #endif
         assert(_PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG));
-        Py_XSETREF(entry->name, Py_NewRef(name));
+        Py_SETREF(entry->name, Py_NewRef(name));
     }
     return res;
 }

From 852c380da83124d269e07b9c4ed4e55392b876c0 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 20:34:40 +0800
Subject: [PATCH 03/12] remove old code

---
 Python/sysmodule.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index b367c5e867db9b..d2cb87edb55c19 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1937,9 +1937,7 @@ static PyObject *
 sys__clear_type_cache_impl(PyObject *module)
 /*[clinic end generated code: output=20e48ca54a6f6971 input=127f3e04a8d9b555]*/
 {
-    // Don't reset the global tp_version_tag. It causes version tag resuse and
-    // cache inconsistencies.
-    _PyType_ClearCache_NoResetGlobalVersionTag();
+    PyType_ClearCache();
     Py_RETURN_NONE;
 }
 

From f78d56237e0e0be32c805f982a242c37f1c55352 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 20:36:11 +0800
Subject: [PATCH 04/12] cast to unsigned long

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

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index d2cb87edb55c19..fb524e00421e13 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1962,7 +1962,8 @@ sys__get_type_version_tag(PyObject *module, PyObject *type)
         _PyErr_SetString(tstate, PyExc_TypeError, "argument must be a type");
         return NULL;
     }
-    PyObject *res = PyLong_FromUnsignedLong(((PyTypeObject *)type)->tp_version_tag);
+    PyObject *res = PyLong_FromUnsignedLong(
+        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
     if (res == NULL) {
         assert(_PyErr_Occurred(tstate));
         return NULL;

From aa2508584e25047b3d06e4fd5e0aed485b901d18 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 20:39:21 +0800
Subject: [PATCH 05/12] test for raise TypeError on non-type

---
 Lib/test/test_sys.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 3b645fbaa17e01..1ec6cd30e7bd2b 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -632,6 +632,7 @@ def test_clear_type_cache(self):
     def test_get_type_version_tag(self):
         test.support.get_attribute(sys, "_get_type_version_tag")
         self.assertIsInstance(sys._get_type_version_tag(int), int)
+        self.assertRaises(TypeError, sys._get_type_version_tag, 1)
 
     def test_ioencoding(self):
         env = dict(os.environ)

From d7ba8f06215e75c74b1191b642a8fc5133439c81 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 23:12:20 +0800
Subject: [PATCH 06/12] Revert changes in sys module, use _testcapimodule,
 handle overflow

---
 Lib/test/test_type_cache.py | 36 ++++++++++++++++++++++--------------
 Modules/_testcapimodule.c   | 18 ++++++++++++++++++
 Python/clinic/sysmodule.c.h | 19 +------------------
 Python/sysmodule.c          | 32 --------------------------------
 4 files changed, 41 insertions(+), 64 deletions(-)

diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
index 638232bcec0c22..4784bc1edae6b7 100644
--- a/Lib/test/test_type_cache.py
+++ b/Lib/test/test_type_cache.py
@@ -2,35 +2,43 @@
 import unittest
 from collections import Counter
 from test import support
+from test.support import import_helper
 try:
-    from sys import _clear_type_cache, _get_type_version_tag
+    from sys import _clear_type_cache
 except ImportError:
     _clear_type_cache = None
 
+# Skip this test if the _testcapi module isn't available.
+type_get_version = import_helper.import_module('_testcapi').type_get_version
+
 msg = "requires sys._clear_type_cache and sys._get_type_version_tag"
-@unittest.skipIf(_clear_type_cache is None, msg)
 @support.cpython_only
+@unittest.skipIf(_clear_type_cache is None, msg)
 class TypeCacheTests(unittest.TestCase):
     def test_tp_version_tag_unique(self):
         """tp_version_tag should be unique assuming no overflow, even after
         clearing type cache.
         """
-        all_version_tags = []
-        append_result = all_version_tags.append
+        # Check if global version tag has already overflowed.
+        Y = type('Y', (), {})
+        Y.x = 1
+        Y.x  # Force a _PyType_Lookup, populating version tag
+        y_ver = type_get_version(Y)
+        # Overflow, or not enough left to conduct the test.
+        if y_ver == 0 or y_ver > 0xFFFFF000:
+            self.skipTest("Out of type version tags")
         # Note: try to avoid any method lookups within this loop,
         # It will affect global version tag.
+        all_version_tags = []
+        append_result = all_version_tags.append
+        assertNotEqual = self.assertNotEqual
         for _ in range(30):
             _clear_type_cache()
-            class C:
-                # __init__ is only here to force
-                # C.tp_version_tag to update when initializing
-                # object C().
-                def __init__(self):
-                    pass
-            x = C()
-            tp_version_tag_after = _get_type_version_tag(C)
-            # Try to avoid self.assertNotEqual to not overflow type cache.
-            assert tp_version_tag_after != 0
+            X = type('Y', (), {})
+            X.x = 1
+            X.x
+            tp_version_tag_after = type_get_version(X)
+            assertNotEqual(tp_version_tag_after, 0, msg="Version overflowed")
             append_result(tp_version_tag_after)
         tp_version_tag, count = Counter(all_version_tags).most_common(1)[0]
         self.assertEqual(count, 1,
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index f338e89f426da0..cf9908128a6bb4 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5575,6 +5575,23 @@ test_fatal_error(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
+// type->tp_version_tag
+static PyObject *
+type_get_version(PyObject *self, PyObject *type)
+{
+    if (!PyType_Check(type)) {
+        PyErr_SetString(PyExc_TypeError, "argument must be a type");
+        return NULL;
+    }
+    PyObject *res = PyLong_FromUnsignedLong(
+        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
+    if (res == NULL) {
+        assert(PyErr_Occurred());
+        return NULL;
+    }
+    return res;
+}
+
 
 static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
 static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
@@ -5854,6 +5871,7 @@ static PyMethodDef TestMethods[] = {
     {"test_py_is_funcs", test_py_is_funcs, METH_NOARGS},
     {"fatal_error", test_fatal_error, METH_VARARGS,
      PyDoc_STR("fatal_error(message, release_gil=False): call Py_FatalError(message)")},
+    {"type_get_version", type_get_version, METH_O, PyDoc_STR("type->tp_version_tag")},
     {NULL, NULL} /* sentinel */
 };
 
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 8e0c558acc5ed7..8350fbf98561a9 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -925,19 +925,6 @@ sys__clear_type_cache(PyObject *module, PyObject *Py_UNUSED(ignored))
     return sys__clear_type_cache_impl(module);
 }
 
-#if defined(Py_DEBUG)
-
-PyDoc_STRVAR(sys__get_type_version_tag__doc__,
-"_get_type_version_tag($module, type, /)\n"
-"--\n"
-"\n"
-"For internal use only: get the `tp_version_tag` of *type*.");
-
-#define SYS__GET_TYPE_VERSION_TAG_METHODDEF    \
-    {"_get_type_version_tag", (PyCFunction)sys__get_type_version_tag, METH_O, sys__get_type_version_tag__doc__},
-
-#endif /* defined(Py_DEBUG) */
-
 PyDoc_STRVAR(sys_is_finalizing__doc__,
 "is_finalizing($module, /)\n"
 "--\n"
@@ -1002,11 +989,7 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
     #define SYS_GETTOTALREFCOUNT_METHODDEF
 #endif /* !defined(SYS_GETTOTALREFCOUNT_METHODDEF) */
 
-#ifndef SYS__GET_TYPE_VERSION_TAG_METHODDEF
-    #define SYS__GET_TYPE_VERSION_TAG_METHODDEF
-#endif /* !defined(SYS__GET_TYPE_VERSION_TAG_METHODDEF) */
-
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=8e0a9df4ee406dcb input=a9049054013a1b77]*/
+/*[clinic end generated code: output=855fc93b2347710b input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index fb524e00421e13..5dfa917e8ffb20 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1941,37 +1941,6 @@ sys__clear_type_cache_impl(PyObject *module)
     Py_RETURN_NONE;
 }
 
-#ifdef Py_DEBUG
-/*[clinic input]
-sys._get_type_version_tag
-
-    type: object
-    /
-
-For internal use only: get the `tp_version_tag` of *type*.
-[clinic start generated code]*/
-
-static PyObject *
-sys__get_type_version_tag(PyObject *module, PyObject *type)
-/*[clinic end generated code: output=bdcfab8b295e0a76 input=6016e5a02b3c3675]*/
-{
-    PyThreadState *tstate = _PyThreadState_GET();
-    _Py_EnsureTstateNotNULL(tstate);
-
-    if (!PyType_Check(type)) {
-        _PyErr_SetString(tstate, PyExc_TypeError, "argument must be a type");
-        return NULL;
-    }
-    PyObject *res = PyLong_FromUnsignedLong(
-        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
-    if (res == NULL) {
-        assert(_PyErr_Occurred(tstate));
-        return NULL;
-    }
-    return res;
-}
-#endif /* Py_DEBUG */
-
 /*[clinic input]
 sys.is_finalizing
 
@@ -2007,7 +1976,6 @@ static PyMethodDef sys_methods[] = {
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
     SYS__CLEAR_TYPE_CACHE_METHODDEF
-    SYS__GET_TYPE_VERSION_TAG_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF
     SYS__CURRENT_EXCEPTIONS_METHODDEF
     SYS_DISPLAYHOOK_METHODDEF

From 5abf657078fff6312764c5598d64c35259a718bf Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 23:14:08 +0800
Subject: [PATCH 07/12] revert changes in test_sys

---
 Lib/test/test_sys.py | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 1ec6cd30e7bd2b..dba4928ec261ac 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -628,12 +628,6 @@ def test_sys_getwindowsversion_no_instantiation(self):
     def test_clear_type_cache(self):
         sys._clear_type_cache()
 
-    @test.support.cpython_only
-    def test_get_type_version_tag(self):
-        test.support.get_attribute(sys, "_get_type_version_tag")
-        self.assertIsInstance(sys._get_type_version_tag(int), int)
-        self.assertRaises(TypeError, sys._get_type_version_tag, 1)
-
     def test_ioencoding(self):
         env = dict(os.environ)
 

From fe0e29c3fdcf926fdc4f0c5953f8a8c62acf2689 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 23:15:22 +0800
Subject: [PATCH 08/12] fix message

---
 Lib/test/test_type_cache.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
index 4784bc1edae6b7..cdd7a67d3572aa 100644
--- a/Lib/test/test_type_cache.py
+++ b/Lib/test/test_type_cache.py
@@ -11,9 +11,8 @@
 # Skip this test if the _testcapi module isn't available.
 type_get_version = import_helper.import_module('_testcapi').type_get_version
 
-msg = "requires sys._clear_type_cache and sys._get_type_version_tag"
 @support.cpython_only
-@unittest.skipIf(_clear_type_cache is None, msg)
+@unittest.skipIf(_clear_type_cache is None, "requires sys._clear_type_cache")
 class TypeCacheTests(unittest.TestCase):
     def test_tp_version_tag_unique(self):
         """tp_version_tag should be unique assuming no overflow, even after

From e907b5d415e6bce1efffd5d13293c7c874eae813 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Mon, 16 Aug 2021 23:45:21 +0800
Subject: [PATCH 09/12] use sys over _testcapimodule

---
 Lib/test/test_sys.py        |  6 ++++++
 Lib/test/test_type_cache.py | 15 ++++++---------
 Modules/_testcapimodule.c   | 18 ------------------
 Python/clinic/sysmodule.c.h | 19 ++++++++++++++++++-
 Python/sysmodule.c          | 32 ++++++++++++++++++++++++++++++++
 5 files changed, 62 insertions(+), 28 deletions(-)

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index dba4928ec261ac..1ec6cd30e7bd2b 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -628,6 +628,12 @@ def test_sys_getwindowsversion_no_instantiation(self):
     def test_clear_type_cache(self):
         sys._clear_type_cache()
 
+    @test.support.cpython_only
+    def test_get_type_version_tag(self):
+        test.support.get_attribute(sys, "_get_type_version_tag")
+        self.assertIsInstance(sys._get_type_version_tag(int), int)
+        self.assertRaises(TypeError, sys._get_type_version_tag, 1)
+
     def test_ioencoding(self):
         env = dict(os.environ)
 
diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
index cdd7a67d3572aa..2613f7d974ea4d 100644
--- a/Lib/test/test_type_cache.py
+++ b/Lib/test/test_type_cache.py
@@ -2,17 +2,14 @@
 import unittest
 from collections import Counter
 from test import support
-from test.support import import_helper
 try:
-    from sys import _clear_type_cache
+    from sys import _clear_type_cache, _get_type_version_tag
 except ImportError:
     _clear_type_cache = None
 
-# Skip this test if the _testcapi module isn't available.
-type_get_version = import_helper.import_module('_testcapi').type_get_version
-
+msg = "requires sys._clear_type_cache and _get_type_version_tag"
 @support.cpython_only
-@unittest.skipIf(_clear_type_cache is None, "requires sys._clear_type_cache")
+@unittest.skipIf(_clear_type_cache is None, msg)
 class TypeCacheTests(unittest.TestCase):
     def test_tp_version_tag_unique(self):
         """tp_version_tag should be unique assuming no overflow, even after
@@ -22,11 +19,11 @@ def test_tp_version_tag_unique(self):
         Y = type('Y', (), {})
         Y.x = 1
         Y.x  # Force a _PyType_Lookup, populating version tag
-        y_ver = type_get_version(Y)
+        y_ver = _get_type_version_tag (Y)
         # Overflow, or not enough left to conduct the test.
         if y_ver == 0 or y_ver > 0xFFFFF000:
             self.skipTest("Out of type version tags")
-        # Note: try to avoid any method lookups within this loop,
+        # Note: try to avoid any method lookups within this loop.
         # It will affect global version tag.
         all_version_tags = []
         append_result = all_version_tags.append
@@ -36,7 +33,7 @@ def test_tp_version_tag_unique(self):
             X = type('Y', (), {})
             X.x = 1
             X.x
-            tp_version_tag_after = type_get_version(X)
+            tp_version_tag_after = _get_type_version_tag(X)
             assertNotEqual(tp_version_tag_after, 0, msg="Version overflowed")
             append_result(tp_version_tag_after)
         tp_version_tag, count = Counter(all_version_tags).most_common(1)[0]
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index cf9908128a6bb4..f338e89f426da0 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5575,23 +5575,6 @@ test_fatal_error(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
-// type->tp_version_tag
-static PyObject *
-type_get_version(PyObject *self, PyObject *type)
-{
-    if (!PyType_Check(type)) {
-        PyErr_SetString(PyExc_TypeError, "argument must be a type");
-        return NULL;
-    }
-    PyObject *res = PyLong_FromUnsignedLong(
-        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
-    if (res == NULL) {
-        assert(PyErr_Occurred());
-        return NULL;
-    }
-    return res;
-}
-
 
 static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
 static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
@@ -5871,7 +5854,6 @@ static PyMethodDef TestMethods[] = {
     {"test_py_is_funcs", test_py_is_funcs, METH_NOARGS},
     {"fatal_error", test_fatal_error, METH_VARARGS,
      PyDoc_STR("fatal_error(message, release_gil=False): call Py_FatalError(message)")},
-    {"type_get_version", type_get_version, METH_O, PyDoc_STR("type->tp_version_tag")},
     {NULL, NULL} /* sentinel */
 };
 
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 8350fbf98561a9..8e0c558acc5ed7 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -925,6 +925,19 @@ sys__clear_type_cache(PyObject *module, PyObject *Py_UNUSED(ignored))
     return sys__clear_type_cache_impl(module);
 }
 
+#if defined(Py_DEBUG)
+
+PyDoc_STRVAR(sys__get_type_version_tag__doc__,
+"_get_type_version_tag($module, type, /)\n"
+"--\n"
+"\n"
+"For internal use only: get the `tp_version_tag` of *type*.");
+
+#define SYS__GET_TYPE_VERSION_TAG_METHODDEF    \
+    {"_get_type_version_tag", (PyCFunction)sys__get_type_version_tag, METH_O, sys__get_type_version_tag__doc__},
+
+#endif /* defined(Py_DEBUG) */
+
 PyDoc_STRVAR(sys_is_finalizing__doc__,
 "is_finalizing($module, /)\n"
 "--\n"
@@ -989,7 +1002,11 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
     #define SYS_GETTOTALREFCOUNT_METHODDEF
 #endif /* !defined(SYS_GETTOTALREFCOUNT_METHODDEF) */
 
+#ifndef SYS__GET_TYPE_VERSION_TAG_METHODDEF
+    #define SYS__GET_TYPE_VERSION_TAG_METHODDEF
+#endif /* !defined(SYS__GET_TYPE_VERSION_TAG_METHODDEF) */
+
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=855fc93b2347710b input=a9049054013a1b77]*/
+/*[clinic end generated code: output=8e0a9df4ee406dcb input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 5dfa917e8ffb20..fb524e00421e13 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1941,6 +1941,37 @@ sys__clear_type_cache_impl(PyObject *module)
     Py_RETURN_NONE;
 }
 
+#ifdef Py_DEBUG
+/*[clinic input]
+sys._get_type_version_tag
+
+    type: object
+    /
+
+For internal use only: get the `tp_version_tag` of *type*.
+[clinic start generated code]*/
+
+static PyObject *
+sys__get_type_version_tag(PyObject *module, PyObject *type)
+/*[clinic end generated code: output=bdcfab8b295e0a76 input=6016e5a02b3c3675]*/
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+    _Py_EnsureTstateNotNULL(tstate);
+
+    if (!PyType_Check(type)) {
+        _PyErr_SetString(tstate, PyExc_TypeError, "argument must be a type");
+        return NULL;
+    }
+    PyObject *res = PyLong_FromUnsignedLong(
+        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
+    if (res == NULL) {
+        assert(_PyErr_Occurred(tstate));
+        return NULL;
+    }
+    return res;
+}
+#endif /* Py_DEBUG */
+
 /*[clinic input]
 sys.is_finalizing
 
@@ -1976,6 +2007,7 @@ static PyMethodDef sys_methods[] = {
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
     SYS__CLEAR_TYPE_CACHE_METHODDEF
+    SYS__GET_TYPE_VERSION_TAG_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF
     SYS__CURRENT_EXCEPTIONS_METHODDEF
     SYS_DISPLAYHOOK_METHODDEF

From 8a01d9c318cf11c08c71bbfd4562c3c0f77bfea5 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Tue, 17 Aug 2021 00:50:21 +0800
Subject: [PATCH 10/12] simplify code

---
 Python/sysmodule.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index fb524e00421e13..a2fb8a1c5165ca 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1955,17 +1955,14 @@ static PyObject *
 sys__get_type_version_tag(PyObject *module, PyObject *type)
 /*[clinic end generated code: output=bdcfab8b295e0a76 input=6016e5a02b3c3675]*/
 {
-    PyThreadState *tstate = _PyThreadState_GET();
-    _Py_EnsureTstateNotNULL(tstate);
-
     if (!PyType_Check(type)) {
-        _PyErr_SetString(tstate, PyExc_TypeError, "argument must be a type");
+        PyErr_SetString(PyExc_TypeError, "argument must be a type");
         return NULL;
     }
     PyObject *res = PyLong_FromUnsignedLong(
         (unsigned long)((PyTypeObject *)type)->tp_version_tag);
     if (res == NULL) {
-        assert(_PyErr_Occurred(tstate));
+        assert(PyErr_Occurred());
         return NULL;
     }
     return res;

From 2a043e7a2e1d57dfff26cd03bd7537d22a46d6ad Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Tue, 17 Aug 2021 01:02:35 +0800
Subject: [PATCH 11/12] Revert to using _testcapimodule

---
 Lib/test/test_sys.py        |  6 ------
 Lib/test/test_type_cache.py | 15 +++++++++------
 Modules/_testcapimodule.c   | 18 ++++++++++++++++++
 Python/clinic/sysmodule.c.h | 19 +------------------
 Python/sysmodule.c          | 29 -----------------------------
 5 files changed, 28 insertions(+), 59 deletions(-)

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 1ec6cd30e7bd2b..dba4928ec261ac 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -628,12 +628,6 @@ def test_sys_getwindowsversion_no_instantiation(self):
     def test_clear_type_cache(self):
         sys._clear_type_cache()
 
-    @test.support.cpython_only
-    def test_get_type_version_tag(self):
-        test.support.get_attribute(sys, "_get_type_version_tag")
-        self.assertIsInstance(sys._get_type_version_tag(int), int)
-        self.assertRaises(TypeError, sys._get_type_version_tag, 1)
-
     def test_ioencoding(self):
         env = dict(os.environ)
 
diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
index 2613f7d974ea4d..cdd7a67d3572aa 100644
--- a/Lib/test/test_type_cache.py
+++ b/Lib/test/test_type_cache.py
@@ -2,14 +2,17 @@
 import unittest
 from collections import Counter
 from test import support
+from test.support import import_helper
 try:
-    from sys import _clear_type_cache, _get_type_version_tag
+    from sys import _clear_type_cache
 except ImportError:
     _clear_type_cache = None
 
-msg = "requires sys._clear_type_cache and _get_type_version_tag"
+# Skip this test if the _testcapi module isn't available.
+type_get_version = import_helper.import_module('_testcapi').type_get_version
+
 @support.cpython_only
-@unittest.skipIf(_clear_type_cache is None, msg)
+@unittest.skipIf(_clear_type_cache is None, "requires sys._clear_type_cache")
 class TypeCacheTests(unittest.TestCase):
     def test_tp_version_tag_unique(self):
         """tp_version_tag should be unique assuming no overflow, even after
@@ -19,11 +22,11 @@ def test_tp_version_tag_unique(self):
         Y = type('Y', (), {})
         Y.x = 1
         Y.x  # Force a _PyType_Lookup, populating version tag
-        y_ver = _get_type_version_tag (Y)
+        y_ver = type_get_version(Y)
         # Overflow, or not enough left to conduct the test.
         if y_ver == 0 or y_ver > 0xFFFFF000:
             self.skipTest("Out of type version tags")
-        # Note: try to avoid any method lookups within this loop.
+        # Note: try to avoid any method lookups within this loop,
         # It will affect global version tag.
         all_version_tags = []
         append_result = all_version_tags.append
@@ -33,7 +36,7 @@ def test_tp_version_tag_unique(self):
             X = type('Y', (), {})
             X.x = 1
             X.x
-            tp_version_tag_after = _get_type_version_tag(X)
+            tp_version_tag_after = type_get_version(X)
             assertNotEqual(tp_version_tag_after, 0, msg="Version overflowed")
             append_result(tp_version_tag_after)
         tp_version_tag, count = Counter(all_version_tags).most_common(1)[0]
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index f338e89f426da0..cf9908128a6bb4 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5575,6 +5575,23 @@ test_fatal_error(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
+// type->tp_version_tag
+static PyObject *
+type_get_version(PyObject *self, PyObject *type)
+{
+    if (!PyType_Check(type)) {
+        PyErr_SetString(PyExc_TypeError, "argument must be a type");
+        return NULL;
+    }
+    PyObject *res = PyLong_FromUnsignedLong(
+        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
+    if (res == NULL) {
+        assert(PyErr_Occurred());
+        return NULL;
+    }
+    return res;
+}
+
 
 static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
 static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
@@ -5854,6 +5871,7 @@ static PyMethodDef TestMethods[] = {
     {"test_py_is_funcs", test_py_is_funcs, METH_NOARGS},
     {"fatal_error", test_fatal_error, METH_VARARGS,
      PyDoc_STR("fatal_error(message, release_gil=False): call Py_FatalError(message)")},
+    {"type_get_version", type_get_version, METH_O, PyDoc_STR("type->tp_version_tag")},
     {NULL, NULL} /* sentinel */
 };
 
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 8e0c558acc5ed7..8350fbf98561a9 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -925,19 +925,6 @@ sys__clear_type_cache(PyObject *module, PyObject *Py_UNUSED(ignored))
     return sys__clear_type_cache_impl(module);
 }
 
-#if defined(Py_DEBUG)
-
-PyDoc_STRVAR(sys__get_type_version_tag__doc__,
-"_get_type_version_tag($module, type, /)\n"
-"--\n"
-"\n"
-"For internal use only: get the `tp_version_tag` of *type*.");
-
-#define SYS__GET_TYPE_VERSION_TAG_METHODDEF    \
-    {"_get_type_version_tag", (PyCFunction)sys__get_type_version_tag, METH_O, sys__get_type_version_tag__doc__},
-
-#endif /* defined(Py_DEBUG) */
-
 PyDoc_STRVAR(sys_is_finalizing__doc__,
 "is_finalizing($module, /)\n"
 "--\n"
@@ -1002,11 +989,7 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
     #define SYS_GETTOTALREFCOUNT_METHODDEF
 #endif /* !defined(SYS_GETTOTALREFCOUNT_METHODDEF) */
 
-#ifndef SYS__GET_TYPE_VERSION_TAG_METHODDEF
-    #define SYS__GET_TYPE_VERSION_TAG_METHODDEF
-#endif /* !defined(SYS__GET_TYPE_VERSION_TAG_METHODDEF) */
-
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=8e0a9df4ee406dcb input=a9049054013a1b77]*/
+/*[clinic end generated code: output=855fc93b2347710b input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index a2fb8a1c5165ca..5dfa917e8ffb20 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1941,34 +1941,6 @@ sys__clear_type_cache_impl(PyObject *module)
     Py_RETURN_NONE;
 }
 
-#ifdef Py_DEBUG
-/*[clinic input]
-sys._get_type_version_tag
-
-    type: object
-    /
-
-For internal use only: get the `tp_version_tag` of *type*.
-[clinic start generated code]*/
-
-static PyObject *
-sys__get_type_version_tag(PyObject *module, PyObject *type)
-/*[clinic end generated code: output=bdcfab8b295e0a76 input=6016e5a02b3c3675]*/
-{
-    if (!PyType_Check(type)) {
-        PyErr_SetString(PyExc_TypeError, "argument must be a type");
-        return NULL;
-    }
-    PyObject *res = PyLong_FromUnsignedLong(
-        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
-    if (res == NULL) {
-        assert(PyErr_Occurred());
-        return NULL;
-    }
-    return res;
-}
-#endif /* Py_DEBUG */
-
 /*[clinic input]
 sys.is_finalizing
 
@@ -2004,7 +1976,6 @@ static PyMethodDef sys_methods[] = {
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
     SYS__CLEAR_TYPE_CACHE_METHODDEF
-    SYS__GET_TYPE_VERSION_TAG_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF
     SYS__CURRENT_EXCEPTIONS_METHODDEF
     SYS_DISPLAYHOOK_METHODDEF

From 7c60a68f548e0dd0d2ac5507dbba1c8a1b32a9a9 Mon Sep 17 00:00:00 2001
From: Fidget-Spinner <28750310+Fidget-Spinner@users.noreply.github.com>
Date: Tue, 17 Aug 2021 01:06:36 +0800
Subject: [PATCH 12/12] Apply Victor's suggestions

---
 Lib/test/test_type_cache.py | 7 +++----
 Modules/_testcapimodule.c   | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/Lib/test/test_type_cache.py b/Lib/test/test_type_cache.py
index cdd7a67d3572aa..8502f6b0584b00 100644
--- a/Lib/test/test_type_cache.py
+++ b/Lib/test/test_type_cache.py
@@ -1,6 +1,5 @@
 """ Tests for the internal type cache in CPython. """
 import unittest
-from collections import Counter
 from test import support
 from test.support import import_helper
 try:
@@ -11,6 +10,7 @@
 # Skip this test if the _testcapi module isn't available.
 type_get_version = import_helper.import_module('_testcapi').type_get_version
 
+
 @support.cpython_only
 @unittest.skipIf(_clear_type_cache is None, "requires sys._clear_type_cache")
 class TypeCacheTests(unittest.TestCase):
@@ -39,9 +39,8 @@ def test_tp_version_tag_unique(self):
             tp_version_tag_after = type_get_version(X)
             assertNotEqual(tp_version_tag_after, 0, msg="Version overflowed")
             append_result(tp_version_tag_after)
-        tp_version_tag, count = Counter(all_version_tags).most_common(1)[0]
-        self.assertEqual(count, 1,
-                         msg=f"tp_version_tag {tp_version_tag} was not unique")
+        self.assertEqual(len(set(all_version_tags)), 30,
+                         msg=f"{all_version_tags} contains non-unique versions")
 
 
 if __name__ == "__main__":
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index cf9908128a6bb4..c35eac78ebe880 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5584,7 +5584,7 @@ type_get_version(PyObject *self, PyObject *type)
         return NULL;
     }
     PyObject *res = PyLong_FromUnsignedLong(
-        (unsigned long)((PyTypeObject *)type)->tp_version_tag);
+        ((PyTypeObject *)type)->tp_version_tag);
     if (res == NULL) {
         assert(PyErr_Occurred());
         return NULL;