From a9ecfcef9c9af6faf2f7853aaccaf6482a624c96 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 27 May 2024 11:33:56 -0600
Subject: [PATCH 1/5] Clear m_index when clearing a singlephase extension.

---
 Python/import.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Python/import.c b/Python/import.c
index 4f3325aa67bd0a..a546cf9a0cbaee 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -2192,6 +2192,7 @@ clear_singlephase_extension(PyInterpreterState *interp,
             return -1;
         }
     }
+    def->m_base.m_index = 0;
 
     /* Clear the cached module def. */
     _extensions_cache_delete(path, name);

From b01ac6e0f584f3049ac18cf24d3ac560ecac9f59 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 27 May 2024 11:35:31 -0600
Subject: [PATCH 2/5] Add a note about the check-state-first modules.

---
 Modules/_testsinglephase.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Modules/_testsinglephase.c b/Modules/_testsinglephase.c
index bcdb5ba31842fd..066e0dbfb63fbf 100644
--- a/Modules/_testsinglephase.c
+++ b/Modules/_testsinglephase.c
@@ -682,6 +682,9 @@ PyInit__testsinglephase_with_state(void)
 /* the _testsinglephase_*_check_cache_first modules */
 /****************************************************/
 
+/* Each of these modules should only be freshly loaded.  That means
+   clearing the caches and each module def's m_base after each load. */
+
 static struct PyModuleDef _testsinglephase_check_cache_first = {
     PyModuleDef_HEAD_INIT,
     .m_name = "_testsinglephase_check_cache_first",

From 6054a7d8ec0de89c1ea65e34c98c099502e38673 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 27 May 2024 11:38:02 -0600
Subject: [PATCH 3/5] Clear the check-state-first modules after loading them.

---
 Lib/test/test_import/__init__.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Lib/test/test_import/__init__.py b/Lib/test/test_import/__init__.py
index 11eaae5e47e97a..b09065f812c0e4 100644
--- a/Lib/test/test_import/__init__.py
+++ b/Lib/test/test_import/__init__.py
@@ -2887,12 +2887,15 @@ def test_with_reinit_reloaded(self):
 
                 self.assertIs(reloaded.snapshot.cached, reloaded.module)
 
+    @unittest.skipIf(_testinternalcapi is None, "requires _testinternalcapi")
     def test_check_state_first(self):
         for variant in ['', '_with_reinit', '_with_state']:
             name = f'{self.NAME}{variant}_check_cache_first'
             with self.subTest(name):
                 mod = self._load_dynamic(name, self.ORIGIN)
                 self.assertEqual(mod.__name__, name)
+                sys.modules.pop(name, None)
+                _testinternalcapi.clear_extension(name, self.ORIGIN)
 
     # Currently, for every single-phrase init module loaded
     # in multiple interpreters, those interpreters share a

From 7a23841d787c07a84b5537095768ae1eb4e85fa6 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 27 May 2024 12:57:31 -0600
Subject: [PATCH 4/5] Fix _modules_by_index_check().

---
 Python/import.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Python/import.c b/Python/import.c
index a546cf9a0cbaee..7af969d13c39dc 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -494,7 +494,7 @@ _modules_by_index_check(PyInterpreterState *interp, Py_ssize_t index)
     if (MODULES_BY_INDEX(interp) == NULL) {
         return "Interpreters module-list not accessible.";
     }
-    if (index > PyList_GET_SIZE(MODULES_BY_INDEX(interp))) {
+    if (index >= PyList_GET_SIZE(MODULES_BY_INDEX(interp))) {
         return "Module index out of bounds.";
     }
     return NULL;

From 3699d15b75b5c0d33b121dd5111cd3f2ba6d80f9 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 27 May 2024 12:58:02 -0600
Subject: [PATCH 5/5] Move a line up.

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

diff --git a/Python/import.c b/Python/import.c
index 7af969d13c39dc..6fe6df4db4f55e 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -2183,7 +2183,7 @@ clear_singlephase_extension(PyInterpreterState *interp,
     /* Clear data set when the module was initially loaded. */
     def->m_base.m_init = NULL;
     Py_CLEAR(def->m_base.m_copy);
-    // We leave m_index alone since there's no reason to reset it.
+    def->m_base.m_index = 0;
 
     /* Clear the PyState_*Module() cache entry. */
     Py_ssize_t index = _get_cached_module_index(cached);
@@ -2192,7 +2192,6 @@ clear_singlephase_extension(PyInterpreterState *interp,
             return -1;
         }
     }
-    def->m_base.m_index = 0;
 
     /* Clear the cached module def. */
     _extensions_cache_delete(path, name);