From 485ad40d43ec97b48ad006c1c75b9592936743f7 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Mon, 30 Oct 2023 18:09:13 +0100
Subject: [PATCH] gh-111506: Implement Py_SET_REFCNT() as opaque function in
 limited C API

In the limited C API version 3.13. Py_SET_REFCNT() is now implemented
as an opaque function call.

Add _Py_SetRefcnt() to the stable ABI.
---
 Include/object.h     | 13 +++++++++++--
 Misc/stable_abi.toml |  2 ++
 Objects/object.c     |  8 ++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/Include/object.h b/Include/object.h
index 6f116ef35a790c6..b4ef3bb5c812af8 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -329,7 +329,15 @@ static inline int Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
 #endif
 
 
+// Py_SET_REFCNT() implementation for stable ABI
+PyAPI_FUNC(void) _Py_SetRefcnt(PyObject *ob, Py_ssize_t refcnt);
+
 static inline void Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
+#if defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030d0000
+    // Stable ABI implements Py_SET_REFCNT() as a function call
+    // on limited C API version 3.13 and newer.
+    _Py_SetRefcnt(ob, refcnt);
+#else
     // This immortal check is for code that is unaware of immortal objects.
     // The runtime tracks these objects and we should avoid as much
     // as possible having extensions inadvertently change the refcnt
@@ -337,7 +345,7 @@ static inline void Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
     if (_Py_IsImmortal(ob)) {
         return;
     }
-#if !defined(Py_NOGIL)
+#ifndef Py_NOGIL
     ob->ob_refcnt = refcnt;
 #else
     if (_Py_IsOwnedByCurrentThread(ob)) {
@@ -354,7 +362,8 @@ static inline void Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
         ob->ob_ref_local = 0;
         ob->ob_ref_shared = _Py_REF_SHARED(refcnt, _Py_REF_MERGED);
     }
-#endif
+#endif  // Py_NOGIL
+#endif  // Py_LIMITED_API+0 < 0x030d0000
 }
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
 #  define Py_SET_REFCNT(ob, refcnt) Py_SET_REFCNT(_PyObject_CAST(ob), (refcnt))
diff --git a/Misc/stable_abi.toml b/Misc/stable_abi.toml
index 0601de20fe0f46b..b00e9034978e46a 100644
--- a/Misc/stable_abi.toml
+++ b/Misc/stable_abi.toml
@@ -2480,3 +2480,5 @@
     added = '3.13'
 [function.PyUnicode_AsUTF8]
     added = '3.13'
+[function._Py_SetRefcnt]
+    added = '3.13'
diff --git a/Objects/object.c b/Objects/object.c
index 35c7e7bf33b1350..1cc3f9146467094 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -2931,3 +2931,11 @@ int Py_IsFalse(PyObject *x)
 {
     return Py_Is(x, Py_False);
 }
+
+
+// Py_SET_REFCNT() implementation for stable ABI
+void
+_Py_SetRefcnt(PyObject *ob, Py_ssize_t refcnt)
+{
+    Py_SET_REFCNT(ob, refcnt);
+}