gh-89653: PEP 670: Functions don't cast pointers (#91697)

In the limited C API version 3.11 and newer, the following functions
no longer cast their object pointer argument with _PyObject_CAST() or
_PyObject_CAST_CONST():

* Py_REFCNT(), Py_TYPE(), Py_SIZE()
* Py_SET_REFCNT(), Py_SET_TYPE(), Py_SET_SIZE()
* Py_IS_TYPE()
* Py_INCREF(), Py_DECREF()
* Py_XINCREF(), Py_XDECREF()
* Py_NewRef(), Py_XNewRef()
* PyObject_TypeCheck()
* PyType_Check()
* PyType_CheckExact()

Split Py_DECREF() implementation in 3 versions to make the code more
readable.

Update the xxlimited.c extension, which uses the limited C API
version 3.11, to pass PyObject* to these functions.

1 files changed, 66 insertions, 35 deletions

diff --git a/Include/object.h b/Include/object.h
index 8a45ddb..5622305 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -123,44 +123,58 @@ PyAPI_FUNC(int) Py_Is(PyObject *x, PyObject *y);
 static inline Py_ssize_t Py_REFCNT(PyObject *ob) {
     return ob->ob_refcnt;
 }
-#define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))
+#endif
 
 
 // bpo-39573: The Py_SET_TYPE() function must be used to set an object type.
 static inline PyTypeObject* Py_TYPE(PyObject *ob) {
     return ob->ob_type;
 }
-#define Py_TYPE(ob) Py_TYPE(_PyObject_CAST(ob))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_TYPE(ob) Py_TYPE(_PyObject_CAST(ob))
+#endif
 
 // bpo-39573: The Py_SET_SIZE() function must be used to set an object size.
 static inline Py_ssize_t Py_SIZE(PyVarObject *ob) {
     return ob->ob_size;
 }
-#define Py_SIZE(ob) Py_SIZE(_PyVarObject_CAST(ob))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_SIZE(ob) Py_SIZE(_PyVarObject_CAST(ob))
+#endif
 
 
 static inline int Py_IS_TYPE(PyObject *ob, PyTypeObject *type) {
     return Py_TYPE(ob) == type;
 }
-#define Py_IS_TYPE(ob, type) Py_IS_TYPE(_PyObject_CAST(ob), type)
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_IS_TYPE(ob, type) Py_IS_TYPE(_PyObject_CAST(ob), type)
+#endif
 
 
 static inline void Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) {
     ob->ob_refcnt = refcnt;
 }
-#define Py_SET_REFCNT(ob, refcnt) Py_SET_REFCNT(_PyObject_CAST(ob), refcnt)
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_SET_REFCNT(ob, refcnt) Py_SET_REFCNT(_PyObject_CAST(ob), refcnt)
+#endif
 
 
 static inline void Py_SET_TYPE(PyObject *ob, PyTypeObject *type) {
     ob->ob_type = type;
 }
-#define Py_SET_TYPE(ob, type) Py_SET_TYPE(_PyObject_CAST(ob), type)
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_SET_TYPE(ob, type) Py_SET_TYPE(_PyObject_CAST(ob), type)
+#endif
 
 
 static inline void Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size) {
     ob->ob_size = size;
 }
-#define Py_SET_SIZE(ob, size) Py_SET_SIZE(_PyVarObject_CAST(ob), size)
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_SET_SIZE(ob, size) Py_SET_SIZE(_PyVarObject_CAST(ob), size)
+#endif
 
 
 /*
@@ -247,7 +261,9 @@ PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
 static inline int PyObject_TypeCheck(PyObject *ob, PyTypeObject *type) {
     return Py_IS_TYPE(ob, type) || PyType_IsSubtype(Py_TYPE(ob), type);
 }
-#define PyObject_TypeCheck(ob, type) PyObject_TypeCheck(_PyObject_CAST(ob), type)
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define PyObject_TypeCheck(ob, type) PyObject_TypeCheck(_PyObject_CAST(ob), type)
+#endif
 
 PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
 PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
@@ -485,39 +501,43 @@ static inline void Py_INCREF(PyObject *op)
     op->ob_refcnt++;
 #endif
 }
-#define Py_INCREF(op) Py_INCREF(_PyObject_CAST(op))
-
-static inline void Py_DECREF(
-#if defined(Py_REF_DEBUG) && !(defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000)
-    const char *filename, int lineno,
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_INCREF(op) Py_INCREF(_PyObject_CAST(op))
 #endif
-    PyObject *op)
-{
+
+
 #if defined(Py_REF_DEBUG) && defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000
-    // Stable ABI for Python 3.10 built in debug mode.
+// Stable ABI for limited C API version 3.10 of Python debug build
+static inline void Py_DECREF(PyObject *op) {
     _Py_DecRef(op);
-#else
-    // Non-limited C API and limited C API for Python 3.9 and older access
-    // directly PyObject.ob_refcnt.
-#ifdef Py_REF_DEBUG
+}
+#define Py_DECREF(op) Py_DECREF(_PyObject_CAST(op))
+
+#elif defined(Py_REF_DEBUG)
+static inline void Py_DECREF(const char *filename, int lineno, PyObject *op)
+{
     _Py_RefTotal--;
-#endif
     if (--op->ob_refcnt != 0) {
-#ifdef Py_REF_DEBUG
         if (op->ob_refcnt < 0) {
             _Py_NegativeRefcount(filename, lineno, op);
         }
-#endif
     }
     else {
         _Py_Dealloc(op);
     }
-#endif
 }
-#if defined(Py_REF_DEBUG) && !(defined(Py_LIMITED_API) && Py_LIMITED_API+0 >= 0x030A0000)
-#  define Py_DECREF(op) Py_DECREF(__FILE__, __LINE__, _PyObject_CAST(op))
+#define Py_DECREF(op) Py_DECREF(__FILE__, __LINE__, _PyObject_CAST(op))
+
 #else
-#  define Py_DECREF(op) Py_DECREF(_PyObject_CAST(op))
+static inline void Py_DECREF(PyObject *op)
+{
+    // Non-limited C API and limited C API for Python 3.9 and older access
+    // directly PyObject.ob_refcnt.
+    if (--op->ob_refcnt == 0) {
+        _Py_Dealloc(op);
+    }
+}
+#define Py_DECREF(op) Py_DECREF(_PyObject_CAST(op))
 #endif
 
 
@@ -571,8 +591,9 @@ static inline void Py_XINCREF(PyObject *op)
         Py_INCREF(op);
     }
 }
-
-#define Py_XINCREF(op) Py_XINCREF(_PyObject_CAST(op))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_XINCREF(op) Py_XINCREF(_PyObject_CAST(op))
+#endif
 
 static inline void Py_XDECREF(PyObject *op)
 {
@@ -580,8 +601,9 @@ static inline void Py_XDECREF(PyObject *op)
         Py_DECREF(op);
     }
 }
-
-#define Py_XDECREF(op) Py_XDECREF(_PyObject_CAST(op))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_XDECREF(op) Py_XDECREF(_PyObject_CAST(op))
+#endif
 
 // Create a new strong reference to an object:
 // increment the reference count of the object and return the object.
@@ -605,8 +627,13 @@ static inline PyObject* _Py_XNewRef(PyObject *obj)
 // Py_NewRef() and Py_XNewRef() are exported as functions for the stable ABI.
 // Names overridden with macros by static inline functions for best
 // performances.
-#define Py_NewRef(obj) _Py_NewRef(_PyObject_CAST(obj))
-#define Py_XNewRef(obj) _Py_XNewRef(_PyObject_CAST(obj))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define Py_NewRef(obj) _Py_NewRef(_PyObject_CAST(obj))
+#  define Py_XNewRef(obj) _Py_XNewRef(_PyObject_CAST(obj))
+#else
+#  define Py_NewRef(obj) _Py_NewRef(obj)
+#  define Py_XNewRef(obj) _Py_XNewRef(obj)
+#endif
 
 
 /*
@@ -749,14 +776,18 @@ PyType_HasFeature(PyTypeObject *type, unsigned long feature)
 static inline int PyType_Check(PyObject *op) {
     return PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS);
 }
-#define PyType_Check(op) PyType_Check(_PyObject_CAST(op))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define PyType_Check(op) PyType_Check(_PyObject_CAST(op))
+#endif
 
 #define _PyType_CAST(op) (assert(PyType_Check(op)), (PyTypeObject*)(op))
 
 static inline int PyType_CheckExact(PyObject *op) {
     return Py_IS_TYPE(op, &PyType_Type);
 }
-#define PyType_CheckExact(op) PyType_CheckExact(_PyObject_CAST(op))
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 < 0x030b0000
+#  define PyType_CheckExact(op) PyType_CheckExact(_PyObject_CAST(op))
+#endif
 
 #ifdef __cplusplus
 }