Isolate tp_mro.

Author: ericsnowcurrently

Include/internal/pycore_typeobject.h

@@ -76,6 +76,8 @@ extern void _PyTypes_Fini(PyInterpreterState *);
 
 /* other API */
 
+extern PyObject * _PyType_GetMRO(PyTypeObject *);
+
 /* Length of array of slotdef pointers used to store slots with the
    same __name__.  There should be at most MAX_EQUIV-1 slotdef entries with
    the same __name__, for any __name__. Since that's a static property, it is

Modules/_abc.c

@@ -7,6 +7,7 @@
 #include "pycore_moduleobject.h"  // _PyModule_GetState()
 #include "pycore_object.h"        // _PyType_GetSubclasses()
 #include "pycore_runtime.h"       // _Py_ID()
+#include "pycore_typeobject.h"    // _PyType_GetMRO()
 #include "clinic/_abc.c.h"
 
 /*[clinic input]
@@ -742,7 +743,7 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     Py_DECREF(ok);
 
     /* 4. Check if it's a direct subclass. */
-    PyObject *mro = ((PyTypeObject *)subclass)->tp_mro;
+    PyObject *mro = _PyType_GetMRO((PyTypeObject *)subclass);
     assert(PyTuple_Check(mro));
     for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
         PyObject *mro_item = PyTuple_GET_ITEM(mro, pos);

Objects/typeobject.c

@@ -871,18 +871,41 @@ type_get_bases(PyTypeObject *type, void *context)
 static inline PyObject *
 get_mro(PyTypeObject *type)
 {
+    if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {
+        static_builtin_state *state = _PyStaticType_GetState(type);
+        assert(state != NULL);
+        return state->tp_mro;
+    }
     return type->tp_mro;
 }
 
+PyObject *
+_PyType_GetMRO(PyTypeObject *type)
+{
+    return get_mro(type);
+}
+
 static inline void
 set_mro(PyTypeObject *type, PyObject *mro)
 {
+    if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {
+        static_builtin_state *state = _PyStaticType_GetState(type);
+        assert(state != NULL);
+        state->tp_mro = mro;
+        return;
+    }
     type->tp_mro = mro;
 }
 
 static inline void
 clear_mro(PyTypeObject *type)
 {
+    if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {
+        static_builtin_state *state = _PyStaticType_GetState(type);
+        assert(state != NULL);
+        Py_CLEAR(state->tp_mro);
+        return;
+    }
     Py_CLEAR(type->tp_mro);
 }
 
@@ -4564,7 +4587,7 @@ clear_static_type_interp_data(PyTypeObject *type)
 
         Py_CLEAR(type->tp_dict);
         Py_CLEAR(state->tp_bases);
-        Py_CLEAR(type->tp_mro);
+        Py_CLEAR(state->tp_mro);
     }
     else {
         Py_CLEAR(type->tp_dict);