[3.12] gh-105020: Share tp_bases and tp_mro Between Interpreters For All Static Builtin Types (gh-105115) (gh-105124)

In gh-103912 we added tp_bases and tp_mro to each PyInterpreterState.types.builtins entry.  However, doing so ignored the fact that both PyTypeObject fields are public API, and not documented as internal (as opposed to tp_subclasses).  We address that here by reverting back to shared objects, making them immortal in the process.
(cherry picked from commit 7be667d)

Co-authored-by: Eric Snow ericsnowcurrently@gmail.com

2 files changed, 17 insertions, 4 deletions

diff --git a/Include/internal/pycore_object.h b/Include/internal/pycore_object.h
index 500b3ee..0981d11 100644
--- a/Include/internal/pycore_object.h
+++ b/Include/internal/pycore_object.h
@@ -76,6 +76,21 @@ static inline void _Py_SetImmortal(PyObject *op)
 }
 #define _Py_SetImmortal(op) _Py_SetImmortal(_PyObject_CAST(op))
 
+/* _Py_ClearImmortal() should only be used during runtime finalization. */
+static inline void _Py_ClearImmortal(PyObject *op)
+{
+    if (op) {
+        assert(op->ob_refcnt == _Py_IMMORTAL_REFCNT);
+        op->ob_refcnt = 1;
+        Py_DECREF(op);
+    }
+}
+#define _Py_ClearImmortal(op) \
+    do { \
+        _Py_ClearImmortal(_PyObject_CAST(op)); \
+        op = NULL; \
+    } while (0)
+
 static inline void
 _Py_DECREF_SPECIALIZED(PyObject *op, const destructor destruct)
 {
diff --git a/Include/internal/pycore_typeobject.h b/Include/internal/pycore_typeobject.h
index c7d0000..8f3fbbc 100644
--- a/Include/internal/pycore_typeobject.h
+++ b/Include/internal/pycore_typeobject.h
@@ -46,11 +46,9 @@ typedef struct {
     PyTypeObject *type;
     int readying;
     int ready;
-    // XXX tp_dict, tp_bases, and tp_mro can probably be statically
-    // allocated, instead of dynamically and stored on the interpreter.
+    // XXX tp_dict can probably be statically allocated,
+    // instead of dynamically and stored on the interpreter.
     PyObject *tp_dict;
-    PyObject *tp_bases;
-    PyObject *tp_mro;
     PyObject *tp_subclasses;
     /* We never clean up weakrefs for static builtin types since
        they will effectively never get triggered.  However, there