From a9dee17af5721656ecbc20c173f494567cd3bf66 Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Mon, 1 Apr 2024 14:05:14 +0900
Subject: [PATCH 01/13] do not cache sub interp capi

---
 Include/datetime.h              | 20 ++++++++++++---
 Lib/test/test_capi/test_misc.py | 16 ++++++++++++
 Modules/_testmultiphase.c       | 43 +++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/Include/datetime.h b/Include/datetime.h
index b78cc0e8e2e5ac..46a743bfd492b8 100644
--- a/Include/datetime.h
+++ b/Include/datetime.h
@@ -194,10 +194,24 @@ typedef struct {
  * */
 #ifndef _PY_DATETIME_IMPL
 /* Define global variable for the C API and a macro for setting it. */
-static PyDateTime_CAPI *PyDateTimeAPI = NULL;
+static PyDateTime_CAPI *_pydatetimeapi_main = NULL;
 
-#define PyDateTime_IMPORT \
-    PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)
+static inline void _import_pydatetime(void) {
+    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
+        _pydatetimeapi_main = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+    }
+}
+#define PyDateTime_IMPORT _import_pydatetime()
+
+static inline PyDateTime_CAPI *_get_pydatetime_api(void) {
+    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
+        return _pydatetimeapi_main;
+    }
+    else {
+        return PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+    }
+}
+#define PyDateTimeAPI _get_pydatetime_api()
 
 /* Macro for access to the UTC singleton */
 #define PyDateTime_TimeZone_UTC PyDateTimeAPI->TimeZone_UTC
diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
index 55a1ab6d6d9359..dd5d57f2a05ec1 100644
--- a/Lib/test/test_capi/test_misc.py
+++ b/Lib/test/test_capi/test_misc.py
@@ -2203,6 +2203,22 @@ def test_module_state_shared_in_global(self):
         subinterp_attr_id = os.read(r, 100)
         self.assertEqual(main_attr_id, subinterp_attr_id)
 
+    @unittest.skipIf(_testmultiphase is None, "test requires _testmultiphase module")
+    def test_datetime_capi(self):
+        script = textwrap.dedent("""
+            import importlib.machinery
+            import importlib.util
+            fullname = '_test_datetime_capi'
+            origin = importlib.util.find_spec('_testmultiphase').origin
+            loader = importlib.machinery.ExtensionFileLoader(fullname, origin)
+            spec = importlib.util.spec_from_loader(fullname, loader)
+            module = importlib.util.module_from_spec(spec)
+            spec.loader.exec_module(module)
+        """)
+        exec(script)
+        ret = support.run_in_subinterp(script)
+        self.assertEqual(ret, 0)
+
 
 @requires_subinterpreters
 class InterpreterIDTests(unittest.TestCase):
diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index 21c5f696a4f2ec..2220cf408586a5 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -952,3 +952,46 @@ PyInit__test_shared_gil_only(void)
 {
     return PyModuleDef_Init(&shared_gil_only_def);
 }
+
+
+#include "datetime.h"
+
+static int
+datetime_capi_exec(PyObject *m)
+{
+    _pydatetimeapi_main = NULL;
+    PyDateTime_IMPORT;
+    if (PyDateTimeAPI == NULL) {
+        return -1;
+    }
+    if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
+        return -1;
+    }
+    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
+        if (PyDateTimeAPI != _pydatetimeapi_main) {
+            return -1;
+        }
+    }
+    else {
+        if (PyDateTimeAPI == _pydatetimeapi_main) {
+            return -1;
+        }
+    }
+    return 0;
+}
+
+static PyModuleDef_Slot datetime_capi_slots[] = {
+    {Py_mod_exec, datetime_capi_exec},
+    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+    {0, NULL},
+};
+
+static PyModuleDef datetime_capi_def = TEST_MODULE_DEF("_test_datetime_capi",
+                                                        datetime_capi_slots,
+                                                        testexport_methods);
+
+PyMODINIT_FUNC
+PyInit__test_datetime_capi(void)
+{
+    return PyModuleDef_Init(&datetime_capi_def);
+}

From 4c9d2001686c119a5e452b133c0f091d01514912 Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Mon, 1 Apr 2024 21:07:34 +0900
Subject: [PATCH 02/13] Apply PEP 7

Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
---
 Include/datetime.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Include/datetime.h b/Include/datetime.h
index 46a743bfd492b8..76544a5ece7267 100644
--- a/Include/datetime.h
+++ b/Include/datetime.h
@@ -196,14 +196,16 @@ typedef struct {
 /* Define global variable for the C API and a macro for setting it. */
 static PyDateTime_CAPI *_pydatetimeapi_main = NULL;
 
-static inline void _import_pydatetime(void) {
+static inline void
+_import_pydatetime(void) {
     if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
         _pydatetimeapi_main = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
     }
 }
 #define PyDateTime_IMPORT _import_pydatetime()
 
-static inline PyDateTime_CAPI *_get_pydatetime_api(void) {
+static inline PyDateTime_CAPI *
+_get_pydatetime_api(void) {
     if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
         return _pydatetimeapi_main;
     }

From 836f5cf495a5f1da5326222b47bdb6c214cd61a8 Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Mon, 1 Apr 2024 21:57:58 +0900
Subject: [PATCH 03/13] non-null main on subinterp test

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

diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index 2220cf408586a5..e0494566d0d2e7 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -959,7 +959,10 @@ PyInit__test_shared_gil_only(void)
 static int
 datetime_capi_exec(PyObject *m)
 {
-    _pydatetimeapi_main = NULL;
+    int ismain = PyInterpreterState_Get() == PyInterpreterState_Main();
+    if (ismain) {
+        _pydatetimeapi_main = NULL;
+    }
     PyDateTime_IMPORT;
     if (PyDateTimeAPI == NULL) {
         return -1;
@@ -967,7 +970,7 @@ datetime_capi_exec(PyObject *m)
     if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
         return -1;
     }
-    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
+    if (ismain) {
         if (PyDateTimeAPI != _pydatetimeapi_main) {
             return -1;
         }

From 34f5a6f7cbcc9d0c0c8e966909b38ec230e1bc31 Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Mon, 1 Apr 2024 22:19:58 +0900
Subject: [PATCH 04/13] don't touch main-ptr during tests

---
 Modules/_testmultiphase.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index e0494566d0d2e7..53841ecd84f256 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -959,10 +959,6 @@ PyInit__test_shared_gil_only(void)
 static int
 datetime_capi_exec(PyObject *m)
 {
-    int ismain = PyInterpreterState_Get() == PyInterpreterState_Main();
-    if (ismain) {
-        _pydatetimeapi_main = NULL;
-    }
     PyDateTime_IMPORT;
     if (PyDateTimeAPI == NULL) {
         return -1;
@@ -970,7 +966,7 @@ datetime_capi_exec(PyObject *m)
     if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
         return -1;
     }
-    if (ismain) {
+    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
         if (PyDateTimeAPI != _pydatetimeapi_main) {
             return -1;
         }

From 321ea7d289455691450c31bbd61876bdc5139055 Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Mon, 1 Apr 2024 23:08:55 +0900
Subject: [PATCH 05/13] fix test_datetime_capi()

---
 Modules/_testcapi/datetime.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/Modules/_testcapi/datetime.c b/Modules/_testcapi/datetime.c
index b1796039f0d83a..9803a830a25af1 100644
--- a/Modules/_testcapi/datetime.c
+++ b/Modules/_testcapi/datetime.c
@@ -3,23 +3,11 @@
 #include "datetime.h"             // PyDateTimeAPI
 
 
-static int test_run_counter = 0;
-
 static PyObject *
 test_datetime_capi(PyObject *self, PyObject *args)
 {
-    if (PyDateTimeAPI) {
-        if (test_run_counter) {
-            /* Probably regrtest.py -R */
-            Py_RETURN_NONE;
-        }
-        else {
-            PyErr_SetString(PyExc_AssertionError,
-                            "PyDateTime_CAPI somehow initialized");
-            return NULL;
-        }
-    }
-    test_run_counter++;
+    // PyDateTimeAPI cannot be carried over
+    // with multi-phase init enabled.
     PyDateTime_IMPORT;
 
     if (PyDateTimeAPI) {

From 39186c2f8c6ed80d677fdceed69c864793c7c7cf Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Tue, 2 Apr 2024 00:44:52 +0900
Subject: [PATCH 06/13] check if legacy module or not

---
 Modules/_testmultiphase.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index 53841ecd84f256..65b03eff09fda0 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -973,7 +973,20 @@ datetime_capi_exec(PyObject *m)
     }
     else {
         if (PyDateTimeAPI == _pydatetimeapi_main) {
-            return -1;
+            PyObject *module = PyImport_ImportModule("_datetime");
+            if (module == NULL) {
+                return -1;
+            }
+            PyModuleDef *def = PyModule_GetDef(module);
+            Py_DECREF(module);
+            if (def) {
+                // multi-phase init
+                return -1;
+            }
+            else {
+                // legacy init (shared module)
+                return 0;
+            }
         }
     }
     return 0;

From b8e545fd29ef6340c2b7de58f227a7a406c40731 Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Tue, 2 Apr 2024 01:24:56 +0900
Subject: [PATCH 07/13] try again 836f5cf

---
 Modules/_testmultiphase.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index 65b03eff09fda0..d6d333fd47288e 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -959,6 +959,11 @@ PyInit__test_shared_gil_only(void)
 static int
 datetime_capi_exec(PyObject *m)
 {
+    int ismain = PyInterpreterState_Get() == PyInterpreterState_Main();
+    if (ismain) {
+        _pydatetimeapi_main = NULL;
+    }
+
     PyDateTime_IMPORT;
     if (PyDateTimeAPI == NULL) {
         return -1;
@@ -966,7 +971,7 @@ datetime_capi_exec(PyObject *m)
     if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
         return -1;
     }
-    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
+    if (ismain) {
         if (PyDateTimeAPI != _pydatetimeapi_main) {
             return -1;
         }

From d2de01a8299050afdee88a1c8b25f808172e116f Mon Sep 17 00:00:00 2001
From: neonene <nicesalmon@gmail.com>
Date: Tue, 2 Apr 2024 14:03:37 +0900
Subject: [PATCH 08/13] renames

---
 Lib/test/test_capi/test_misc.py |  6 +++---
 Modules/_testmultiphase.c       | 15 +++++++--------
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
index dd5d57f2a05ec1..9e38ce9992d971 100644
--- a/Lib/test/test_capi/test_misc.py
+++ b/Lib/test/test_capi/test_misc.py
@@ -2204,18 +2204,18 @@ def test_module_state_shared_in_global(self):
         self.assertEqual(main_attr_id, subinterp_attr_id)
 
     @unittest.skipIf(_testmultiphase is None, "test requires _testmultiphase module")
-    def test_datetime_capi(self):
+    def test_datetime_capi_client(self):
         script = textwrap.dedent("""
             import importlib.machinery
             import importlib.util
-            fullname = '_test_datetime_capi'
+            fullname = '_test_datetime_capi_client'
             origin = importlib.util.find_spec('_testmultiphase').origin
             loader = importlib.machinery.ExtensionFileLoader(fullname, origin)
             spec = importlib.util.spec_from_loader(fullname, loader)
             module = importlib.util.module_from_spec(spec)
             spec.loader.exec_module(module)
         """)
-        exec(script)
+        exec(script)  # run main interp first
         ret = support.run_in_subinterp(script)
         self.assertEqual(ret, 0)
 
diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index d6d333fd47288e..e09de1d5a7b793 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -957,7 +957,7 @@ PyInit__test_shared_gil_only(void)
 #include "datetime.h"
 
 static int
-datetime_capi_exec(PyObject *m)
+datetime_capi_client_exec(PyObject *m)
 {
     int ismain = PyInterpreterState_Get() == PyInterpreterState_Main();
     if (ismain) {
@@ -997,18 +997,17 @@ datetime_capi_exec(PyObject *m)
     return 0;
 }
 
-static PyModuleDef_Slot datetime_capi_slots[] = {
-    {Py_mod_exec, datetime_capi_exec},
+static PyModuleDef_Slot datetime_capi_client_slots[] = {
+    {Py_mod_exec, datetime_capi_client_exec},
     {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
     {0, NULL},
 };
 
-static PyModuleDef datetime_capi_def = TEST_MODULE_DEF("_test_datetime_capi",
-                                                        datetime_capi_slots,
-                                                        testexport_methods);
+static PyModuleDef datetime_capi_client_def = TEST_MODULE_DEF(
+    "_testmultiphase_datetime_capi_client", datetime_capi_client_slots, NULL);
 
 PyMODINIT_FUNC
-PyInit__test_datetime_capi(void)
+PyInit__test_datetime_capi_client(void)
 {
-    return PyModuleDef_Init(&datetime_capi_def);
+    return PyModuleDef_Init(&datetime_capi_client_def);
 }

From 1f902728f5b4643c31bece0f5025192ef025d0ee Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Wed, 3 Apr 2024 22:57:00 +0900
Subject: [PATCH 09/13] globals-to-fix.tsv

---
 Tools/c-analyzer/cpython/globals-to-fix.tsv | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Tools/c-analyzer/cpython/globals-to-fix.tsv b/Tools/c-analyzer/cpython/globals-to-fix.tsv
index 65f94e50e1bd7d..f731d3517c8005 100644
--- a/Tools/c-analyzer/cpython/globals-to-fix.tsv
+++ b/Tools/c-analyzer/cpython/globals-to-fix.tsv
@@ -446,6 +446,7 @@ Modules/_tkinter.c	-	trbInCmd	-
 
 ## other
 Include/datetime.h	-	PyDateTimeAPI	-
+Include/datetime.h	-	_pydatetimeapi_main	-
 Modules/_ctypes/cfield.c	_ctypes_get_fielddesc	initialized	-
 Modules/_ctypes/malloc_closure.c	-	_pagesize	-
 Modules/_cursesmodule.c	-	initialised	-

From 777fdbb361c0381cd18b077b27a31a72c9a494ac Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Wed, 3 Apr 2024 23:13:40 +0900
Subject: [PATCH 10/13] edit globals-to-fix

---
 Tools/c-analyzer/cpython/globals-to-fix.tsv | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Tools/c-analyzer/cpython/globals-to-fix.tsv b/Tools/c-analyzer/cpython/globals-to-fix.tsv
index f731d3517c8005..7ba2448afbff2e 100644
--- a/Tools/c-analyzer/cpython/globals-to-fix.tsv
+++ b/Tools/c-analyzer/cpython/globals-to-fix.tsv
@@ -445,7 +445,6 @@ Modules/_tkinter.c	-	trbInCmd	-
 ## initialized once
 
 ## other
-Include/datetime.h	-	PyDateTimeAPI	-
 Include/datetime.h	-	_pydatetimeapi_main	-
 Modules/_ctypes/cfield.c	_ctypes_get_fielddesc	initialized	-
 Modules/_ctypes/malloc_closure.c	-	_pagesize	-

From da769ba5e8cf1da46513a6afb38c3df7b5470fa5 Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Mon, 29 Apr 2024 00:39:56 +0900
Subject: [PATCH 11/13] fix gil-disabled test

---
 Modules/_testmultiphase.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index e09de1d5a7b793..a8ed507f8815d0 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -965,19 +965,20 @@ datetime_capi_client_exec(PyObject *m)
     }
 
     PyDateTime_IMPORT;
-    if (PyDateTimeAPI == NULL) {
-        return -1;
-    }
-    if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
+    PyErr_Clear();
+    PyDateTime_CAPI *capi = PyDateTimeAPI;
+    PyErr_Clear();
+    if (capi != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
         return -1;
     }
+    PyErr_Clear();
     if (ismain) {
-        if (PyDateTimeAPI != _pydatetimeapi_main) {
+        if (capi != _pydatetimeapi_main) {
             return -1;
         }
     }
     else {
-        if (PyDateTimeAPI == _pydatetimeapi_main) {
+        if (capi == _pydatetimeapi_main) {
             PyObject *module = PyImport_ImportModule("_datetime");
             if (module == NULL) {
                 return -1;

From fb2145cb3fa7c067658196cf4e3481a4c6ee2f9e Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Thu, 2 May 2024 00:28:00 +0900
Subject: [PATCH 12/13] use cache instead of interp state

---
 Include/datetime.h                          | 31 ++++----
 Lib/test/datetimetester.py                  |  2 +-
 Lib/test/test_capi/test_misc.py             |  1 +
 Modules/_datetimemodule.c                   | 59 ++++++++++++++++
 Modules/_testcapi/datetime.c                | 16 ++++-
 Modules/_testmultiphase.c                   | 78 +++++++++++++--------
 Tools/c-analyzer/cpython/globals-to-fix.tsv |  2 +-
 Tools/c-analyzer/cpython/ignored.tsv        |  1 +
 8 files changed, 139 insertions(+), 51 deletions(-)

diff --git a/Include/datetime.h b/Include/datetime.h
index 76544a5ece7267..54d80303a281ce 100644
--- a/Include/datetime.h
+++ b/Include/datetime.h
@@ -186,34 +186,31 @@ typedef struct {
 } PyDateTime_CAPI;
 
 #define PyDateTime_CAPSULE_NAME "datetime.datetime_CAPI"
-
+#define PyDateTime_INTERNAL_CAPSULE_NAME "datetime.datetime_CAPI_INTERNAL"
 
 /* This block is only used as part of the public API and should not be
  * included in _datetimemodule.c, which does not use the C API capsule.
  * See bpo-35081 for more details.
  * */
 #ifndef _PY_DATETIME_IMPL
-/* Define global variable for the C API and a macro for setting it. */
-static PyDateTime_CAPI *_pydatetimeapi_main = NULL;
+static PyDateTime_CAPI *
+_PyDateTimeAPI_not_ready(void)
+{
+    return NULL;
+}
+static PyDateTime_CAPI *(*_PyDateTimeAPI_Get)(void) = _PyDateTimeAPI_not_ready;
 
 static inline void
-_import_pydatetime(void) {
-    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
-        _pydatetimeapi_main = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+_PyDateTimeAPI_Import(void)
+{
+    void *(*func)(void) = PyCapsule_Import(PyDateTime_INTERNAL_CAPSULE_NAME, 0);
+    if (func) {
+        _PyDateTimeAPI_Get = func();
     }
 }
-#define PyDateTime_IMPORT _import_pydatetime()
 
-static inline PyDateTime_CAPI *
-_get_pydatetime_api(void) {
-    if (PyInterpreterState_Get() == PyInterpreterState_Main()) {
-        return _pydatetimeapi_main;
-    }
-    else {
-        return PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
-    }
-}
-#define PyDateTimeAPI _get_pydatetime_api()
+#define PyDateTimeAPI _PyDateTimeAPI_Get()
+#define PyDateTime_IMPORT _PyDateTimeAPI_Import()
 
 /* Macro for access to the UTC singleton */
 #define PyDateTime_TimeZone_UTC PyDateTimeAPI->TimeZone_UTC
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 570110893629cf..6946b394e68a82 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -91,7 +91,7 @@ def test_name_cleanup(self):
                     if not name.startswith('__') and not name.endswith('__'))
         allowed = set(['MAXYEAR', 'MINYEAR', 'date', 'datetime',
                        'datetime_CAPI', 'time', 'timedelta', 'timezone',
-                       'tzinfo', 'UTC', 'sys'])
+                       'tzinfo', 'UTC', 'sys', 'datetime_CAPI_INTERNAL'])
         self.assertEqual(names - allowed, set([]))
 
     def test_divide_and_round(self):
diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
index 9786e0d88cbf66..2cbaac346e915c 100644
--- a/Lib/test/test_capi/test_misc.py
+++ b/Lib/test/test_capi/test_misc.py
@@ -2295,6 +2295,7 @@ def test_datetime_capi_client(self):
             spec.loader.exec_module(module)
         """)
         exec(script)  # run main interp first
+        exec(script)  # run main interp twice
         ret = support.run_in_subinterp(script)
         self.assertEqual(ret, 0)
 
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 06004e258b2eff..43088f4b0b047c 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -63,6 +63,51 @@ static datetime_state _datetime_global_state;
 
 #define STATIC_STATE() (&_datetime_global_state)
 
+typedef struct {
+    PyInterpreterState *interp;
+    PyDateTime_CAPI *capi;
+} CAPI_Cache;
+
+static CAPI_Cache apicache[2];
+
+static inline void
+set_datetime_capi_by_interp(PyDateTime_CAPI *capi)
+{
+    PyInterpreterState *interp = PyInterpreterState_Get();
+    int i = interp == PyInterpreterState_Main() ? 0 : 1;
+    apicache[i].interp = interp;
+    apicache[i].capi = capi;
+}
+
+static PyDateTime_CAPI *
+_PyDateTimeAPI_Get(void)
+{
+    PyInterpreterState *interp = PyInterpreterState_Get();
+    for (int i = 0; i < 2; i++) {
+        if (apicache[i].interp == interp) {
+            return apicache[i].capi;
+        }
+    }
+    PyDateTime_CAPI *capi = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+    if (capi) {
+        set_datetime_capi_by_interp(capi);
+    }
+    return capi;
+}
+
+static void *
+_PyDateTimeAPI_Import(void)
+{
+    PyDateTime_CAPI *capi = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+    if (capi) {
+        // PyInit__datetime() is not called when the module is already loaded
+        // with single-phase init.
+        set_datetime_capi_by_interp(capi);
+        return _PyDateTimeAPI_Get;
+    }
+    return NULL;
+}
+
 /* We require that C int be at least 32 bits, and use int virtually
  * everywhere.  In just a few cases we use a temp long, where a Python
  * API returns a C long.  In such cases, we have to ensure that the
@@ -6944,6 +6989,20 @@ _datetime_exec(PyObject *module)
         goto error;
     }
 
+    capsule = PyCapsule_New(_PyDateTimeAPI_Import,
+                            PyDateTime_INTERNAL_CAPSULE_NAME, NULL);
+    if (capsule == NULL) {
+        PyMem_Free(capi);
+        goto error;
+    }
+    if (PyModule_Add(module, "datetime_CAPI_INTERNAL", capsule) < 0) {
+        PyMem_Free(capi);
+        goto error;
+    }
+
+    /* Ensure that the newest capi is used on multi-phase init */
+    set_datetime_capi_by_interp(capi);
+
     /* A 4-year cycle has an extra leap day over what we'd get from
      * pasting together 4 single years.
      */
diff --git a/Modules/_testcapi/datetime.c b/Modules/_testcapi/datetime.c
index 9803a830a25af1..b1796039f0d83a 100644
--- a/Modules/_testcapi/datetime.c
+++ b/Modules/_testcapi/datetime.c
@@ -3,11 +3,23 @@
 #include "datetime.h"             // PyDateTimeAPI
 
 
+static int test_run_counter = 0;
+
 static PyObject *
 test_datetime_capi(PyObject *self, PyObject *args)
 {
-    // PyDateTimeAPI cannot be carried over
-    // with multi-phase init enabled.
+    if (PyDateTimeAPI) {
+        if (test_run_counter) {
+            /* Probably regrtest.py -R */
+            Py_RETURN_NONE;
+        }
+        else {
+            PyErr_SetString(PyExc_AssertionError,
+                            "PyDateTime_CAPI somehow initialized");
+            return NULL;
+        }
+    }
+    test_run_counter++;
     PyDateTime_IMPORT;
 
     if (PyDateTimeAPI) {
diff --git a/Modules/_testmultiphase.c b/Modules/_testmultiphase.c
index a8ed507f8815d0..429824fbede1fa 100644
--- a/Modules/_testmultiphase.c
+++ b/Modules/_testmultiphase.c
@@ -957,44 +957,62 @@ PyInit__test_shared_gil_only(void)
 #include "datetime.h"
 
 static int
-datetime_capi_client_exec(PyObject *m)
+datetime_capi_import_with_error(void)
 {
+    static int is_datetime_multiphase = -1;
     int ismain = PyInterpreterState_Get() == PyInterpreterState_Main();
-    if (ismain) {
-        _pydatetimeapi_main = NULL;
+    if (ismain && is_datetime_multiphase < 0) {
+        PyObject *module = PyImport_ImportModule("_datetime");
+        if (module == NULL) {
+            return -1;
+        }
+        PyModuleDef *def = PyModule_GetDef(module);
+        Py_DECREF(module);
+        if (def && def->m_size >= 0) {
+            is_datetime_multiphase = 1;
+        }
+        else {
+            is_datetime_multiphase = 0;
+        }
+    }
+    if (is_datetime_multiphase < 0) {
+        PyErr_SetString(PyExc_AssertionError,
+                        "Main interpreter must be loaded first.");
+        return -1;
     }
 
-    PyDateTime_IMPORT;
-    PyErr_Clear();
-    PyDateTime_CAPI *capi = PyDateTimeAPI;
-    PyErr_Clear();
-    if (capi != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
+    _PyDateTimeAPI_Import();
+    if (!PyErr_Occurred()) {
+        return 0;
+    }
+#ifdef Py_GIL_DISABLED
+    if (!ismain && !is_datetime_multiphase) {
+        // _datetime module and Capsule are not imported
+        PyErr_WriteUnraisable(NULL);
+        return 0;
+    }
+#endif
+    return -1;
+}
+
+static int
+datetime_capi_client_exec(PyObject *m)
+{
+    _PyDateTimeAPI_Get = _PyDateTimeAPI_not_ready;
+    if (_PyDateTimeAPI_Get() != NULL) {
+        PyErr_SetString(PyExc_AssertionError,
+                        "DateTime API is expected to remain NULL.");
         return -1;
     }
-    PyErr_Clear();
-    if (ismain) {
-        if (capi != _pydatetimeapi_main) {
-            return -1;
-        }
+    if (datetime_capi_import_with_error() < 0) {
+        return -1;
     }
-    else {
-        if (capi == _pydatetimeapi_main) {
-            PyObject *module = PyImport_ImportModule("_datetime");
-            if (module == NULL) {
-                return -1;
-            }
-            PyModuleDef *def = PyModule_GetDef(module);
-            Py_DECREF(module);
-            if (def) {
-                // multi-phase init
-                return -1;
-            }
-            else {
-                // legacy init (shared module)
-                return 0;
-            }
-        }
+    if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
+        PyErr_SetString(PyExc_AssertionError,
+                        "DateTime API does not match Capsule CAPI.");
+        return -1;
     }
+    PyErr_Clear();
     return 0;
 }
 
diff --git a/Tools/c-analyzer/cpython/globals-to-fix.tsv b/Tools/c-analyzer/cpython/globals-to-fix.tsv
index 1fc4e8ae43fb0e..3c0f3b39530d3f 100644
--- a/Tools/c-analyzer/cpython/globals-to-fix.tsv
+++ b/Tools/c-analyzer/cpython/globals-to-fix.tsv
@@ -446,7 +446,7 @@ Modules/_tkinter.c	-	trbInCmd	-
 ## initialized once
 
 ## other
-Include/datetime.h	-	_pydatetimeapi_main	-
+Include/datetime.h	-	_PyDateTimeAPI_Get	-
 Modules/_ctypes/cfield.c	_ctypes_get_fielddesc	initialized	-
 Modules/_ctypes/malloc_closure.c	-	_pagesize	-
 Modules/_cursesmodule.c	-	initialised	-
diff --git a/Tools/c-analyzer/cpython/ignored.tsv b/Tools/c-analyzer/cpython/ignored.tsv
index 87b695de23e25e..11e56658951af8 100644
--- a/Tools/c-analyzer/cpython/ignored.tsv
+++ b/Tools/c-analyzer/cpython/ignored.tsv
@@ -591,6 +591,7 @@ Modules/_testmultiphase.c	-	slots_exec_unreported_exception	-
 Modules/_testmultiphase.c	-	slots_nonmodule_with_exec_slots	-
 Modules/_testmultiphase.c	-	testexport_methods	-
 Modules/_testmultiphase.c	-	uninitialized_def	-
+Modules/_testmultiphase.c	datetime_capi_import_with_error	is_datetime_multiphase	-
 Modules/_testsinglephase.c	-	global_state	-
 Modules/_xxtestfuzz/_xxtestfuzz.c	-	_fuzzmodule	-
 Modules/_xxtestfuzz/_xxtestfuzz.c	-	module_methods	-

From 041b1dd2a2979de9f6c0f560329b384d463d3298 Mon Sep 17 00:00:00 2001
From: neonene <53406459+neonene@users.noreply.github.com>
Date: Thu, 2 May 2024 00:55:02 +0900
Subject: [PATCH 13/13] Update globals-to-fix.tsv

---
 Tools/c-analyzer/cpython/globals-to-fix.tsv | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Tools/c-analyzer/cpython/globals-to-fix.tsv b/Tools/c-analyzer/cpython/globals-to-fix.tsv
index 3c0f3b39530d3f..8f5a7048bcc5f1 100644
--- a/Tools/c-analyzer/cpython/globals-to-fix.tsv
+++ b/Tools/c-analyzer/cpython/globals-to-fix.tsv
@@ -464,6 +464,7 @@ Modules/readline.c	-	libedit_history_start	-
 Modules/_ctypes/cfield.c	-	formattable	-
 Modules/_ctypes/malloc_closure.c	-	free_list	-
 Modules/_curses_panel.c	-	lop	-
+Modules/_datetimemodule.c	-	apicache	-
 Modules/_ssl/debughelpers.c	_PySSL_keylog_callback	lock	-
 Modules/_tkinter.c	-	quitMainLoop	-
 Modules/_tkinter.c	-	errorInCmd	-