gh-139098: Use multiphase initialization in _testcapi (GH-139102)

Use multiphase initialization in the _testcapi module to allow loading in subinterpreters. The isolation here isn't perfect as there's still some use of globals, but _testcapi should generally work in other interpreters.

Author: ZeroIntensity

Modules/_testcapi/heaptype.c

@@ -782,10 +782,7 @@ heapctypesubclasswithfinalizer_finalize(PyObject *self)
     /* Save the current exception, if any. */
     PyObject *exc = PyErr_GetRaisedException();
 
-    if (_testcapimodule == NULL) {
-        goto cleanup_finalize;
-    }
-    PyObject *m = PyState_FindModule(_testcapimodule);
+    PyObject *m = PyType_GetModule(Py_TYPE(self));
     if (m == NULL) {
         goto cleanup_finalize;
     }
@@ -1402,8 +1399,8 @@ _PyTestCapi_Init_Heaptype(PyObject *m) {
     if (subclass_with_finalizer_bases == NULL) {
         return -1;
     }
-    PyObject *HeapCTypeSubclassWithFinalizer = PyType_FromSpecWithBases(
-        &HeapCTypeSubclassWithFinalizer_spec, subclass_with_finalizer_bases);
+    PyObject *HeapCTypeSubclassWithFinalizer = PyType_FromModuleAndSpec(
+        m, &HeapCTypeSubclassWithFinalizer_spec, subclass_with_finalizer_bases);
     Py_DECREF(subclass_with_finalizer_bases);
     ADD("HeapCTypeSubclassWithFinalizer", HeapCTypeSubclassWithFinalizer);
 

Modules/_testcapimodule.c

@@ -3243,75 +3243,56 @@ create_managed_dict_type(void)
    return PyType_FromSpec(&ManagedDict_spec);
 }
 
-static struct PyModuleDef _testcapimodule = {
-    PyModuleDef_HEAD_INIT,
-    .m_name = "_testcapi",
-    .m_size = sizeof(testcapistate_t),
-    .m_methods = TestMethods,
-};
-
-/* Per PEP 489, this module will not be converted to multi-phase initialization
- */
-
-PyMODINIT_FUNC
-PyInit__testcapi(void)
+static int
+_testcapi_exec(PyObject *m)
 {
-    PyObject *m;
-
-    m = PyModule_Create(&_testcapimodule);
-    if (m == NULL)
-        return NULL;
-#ifdef Py_GIL_DISABLED
-    PyUnstable_Module_SetGIL(m, Py_MOD_GIL_NOT_USED);
-#endif
-
     Py_SET_TYPE(&_HashInheritanceTester_Type, &PyType_Type);
     if (PyType_Ready(&_HashInheritanceTester_Type) < 0) {
-        return NULL;
+        return -1;
     }
     if (PyType_Ready(&matmulType) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&matmulType);
     PyModule_AddObject(m, "matmulType", (PyObject *)&matmulType);
     if (PyType_Ready(&ipowType) < 0) {
-        return NULL;
+        return -1;
     }
     Py_INCREF(&ipowType);
     PyModule_AddObject(m, "ipowType", (PyObject *)&ipowType);
 
     if (PyType_Ready(&awaitType) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&awaitType);
     PyModule_AddObject(m, "awaitType", (PyObject *)&awaitType);
 
     MyList_Type.tp_base = &PyList_Type;
     if (PyType_Ready(&MyList_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&MyList_Type);
     PyModule_AddObject(m, "MyList", (PyObject *)&MyList_Type);
 
     if (PyType_Ready(&GenericAlias_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&GenericAlias_Type);
     PyModule_AddObject(m, "GenericAlias", (PyObject *)&GenericAlias_Type);
 
     if (PyType_Ready(&Generic_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&Generic_Type);
     PyModule_AddObject(m, "Generic", (PyObject *)&Generic_Type);
 
     if (PyType_Ready(&MethInstance_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&MethInstance_Type);
     PyModule_AddObject(m, "MethInstance", (PyObject *)&MethInstance_Type);
 
     if (PyType_Ready(&MethClass_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&MethClass_Type);
     PyModule_AddObject(m, "MethClass", (PyObject *)&MethClass_Type);
 
     if (PyType_Ready(&MethStatic_Type) < 0)
-        return NULL;
+        return -1;
     Py_INCREF(&MethStatic_Type);
     PyModule_AddObject(m, "MethStatic", (PyObject *)&MethStatic_Type);
 
@@ -3354,159 +3335,179 @@ PyInit__testcapi(void)
     PyModule_AddObject(m, "UINT64_MAX", PyLong_FromUInt64(UINT64_MAX));
 
     if (PyModule_AddIntMacro(m, Py_single_input)) {
-        return NULL;
+        return -1;
     }
     if (PyModule_AddIntMacro(m, Py_file_input)) {
-        return NULL;
+        return -1;
     }
     if (PyModule_AddIntMacro(m, Py_eval_input)) {
-        return NULL;
+        return -1;
     }
 
     testcapistate_t *state = get_testcapi_state(m);
     state->error = PyErr_NewException("_testcapi.error", NULL, NULL);
     PyModule_AddObject(m, "error", state->error);
 
     if (PyType_Ready(&ContainerNoGC_type) < 0) {
-        return NULL;
+        return -1;
     }
     Py_INCREF(&ContainerNoGC_type);
     if (PyModule_AddObject(m, "ContainerNoGC",
                            (PyObject *) &ContainerNoGC_type) < 0)
-        return NULL;
+        return -1;
 
     PyObject *manual_heap_type = create_manual_heap_type();
     if (manual_heap_type == NULL) {
-        return NULL;
+        return -1;
     }
     if (PyModule_Add(m, "ManualHeapType", manual_heap_type) < 0) {
-        return NULL;
+        return -1;
     }
 
     PyObject *managed_dict_type = create_managed_dict_type();
     if (managed_dict_type == NULL) {
-        return NULL;
+        return -1;
     }
     if (PyModule_Add(m, "ManagedDictType", managed_dict_type) < 0) {
-        return NULL;
+        return -1;
     }
 
     /* Include tests from the _testcapi/ directory */
     if (_PyTestCapi_Init_Vectorcall(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Heaptype(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Abstract(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Bytes(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Unicode(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_GetArgs(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_DateTime(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Docstring(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Mem(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Watchers(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Long(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Float(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Complex(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Numbers(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Dict(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Set(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_List(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Tuple(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Structmember(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Exceptions(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Code(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Buffer(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_File(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Codec(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Immortal(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_GC(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_PyAtomic(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Run(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Hash(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Time(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Modsupport(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Monitoring(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Object(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Config(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Import(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Frame(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Type(m) < 0) {
-        return NULL;
+        return -1;
     }
     if (_PyTestCapi_Init_Function(m) < 0) {
-        return NULL;
+        return -1;
     }
 
-    PyState_AddModule(m, &_testcapimodule);
-    return m;
+    return 0;
+}
+
+static PyModuleDef_Slot _testcapi_slots[] = {
+    {Py_mod_exec, _testcapi_exec},
+    {Py_mod_gil, Py_MOD_GIL_NOT_USED},
+    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+    {0, NULL},
+};
+
+static struct PyModuleDef _testcapimodule = {
+    PyModuleDef_HEAD_INIT,
+    .m_name = "_testcapi",
+    .m_size = sizeof(testcapistate_t),
+    .m_methods = TestMethods,
+    .m_slots = _testcapi_slots
+};
+
+PyMODINIT_FUNC
+PyInit__testcapi(void)
+{
+    return PyModuleDef_Init(&_testcapimodule);
 }