gh-106572: Convert PyObject_DelAttr() to a function (#106611)

* Convert PyObject_DelAttr() and PyObject_DelAttrString() macros to
  functions.
* Add PyObject_DelAttr() and PyObject_DelAttrString() functions to
  the stable ABI.
* Replace PyObject_SetAttr(obj, name, NULL) with
  PyObject_DelAttr(obj, name).

Author: vstinner

Doc/data/stable_abi.dat

@@ -80,25 +80,23 @@ extern "C" {
 
    This is the equivalent of the Python statement o.attr_name=v. */
 
-/* Implemented as a macro:
+/* Implemented elsewhere:
 
    int PyObject_DelAttrString(PyObject *o, const char *attr_name);
 
    Delete attribute named attr_name, for object o. Returns
    -1 on failure.
 
    This is the equivalent of the Python statement: del o.attr_name. */
-#define PyObject_DelAttrString(O, A) PyObject_SetAttrString((O), (A), NULL)
 
 
-/* Implemented as a macro:
+/* Implemented elsewhere:
 
    int PyObject_DelAttr(PyObject *o, PyObject *attr_name);
 
    Delete attribute named attr_name, for object o. Returns -1
    on failure.  This is the equivalent of the Python
    statement: del o.attr_name. */
-#define  PyObject_DelAttr(O, A) PyObject_SetAttr((O), (A), NULL)
 
 
 /* Implemented elsewhere:

Include/abstract.h

@@ -391,9 +391,11 @@ PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
 PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
 PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
 PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
+PyAPI_FUNC(int) PyObject_DelAttrString(PyObject *v, const char *name);
 PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
 PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
 PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(int) PyObject_DelAttr(PyObject *v, PyObject *name);
 PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
 PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
 PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);

Include/object.h

@@ -0,0 +1,2 @@
+Convert :c:func:`PyObject_DelAttr` and :c:func:`PyObject_DelAttrString`
+macros to functions. Patch by Victor Stinner.

Lib/test/test_stable_abi_ctypes.py

@@ -2432,3 +2432,7 @@
     added = '3.13'
 [function.PyWeakref_GetRef]
     added = '3.13'
+[function.PyObject_DelAttr]
+    added = '3.13'
+[function.PyObject_DelAttrString]
+    added = '3.13'

Misc/NEWS.d/next/C API/2023-07-11-01-07-39.gh-issue-106572.y1b35X.rst

@@ -942,6 +942,12 @@ PyObject_SetAttrString(PyObject *v, const char *name, PyObject *w)
     return res;
 }
 
+int
+PyObject_DelAttrString(PyObject *v, const char *name)
+{
+    return PyObject_SetAttrString(v, name, NULL);
+}
+
 int
 _PyObject_IsAbstract(PyObject *obj)
 {
@@ -1185,6 +1191,12 @@ PyObject_SetAttr(PyObject *v, PyObject *name, PyObject *value)
     return -1;
 }
 
+int
+PyObject_DelAttr(PyObject *v, PyObject *name)
+{
+    return PyObject_SetAttr(v, name, NULL);
+}
+
 PyObject **
 _PyObject_ComputedDictPointer(PyObject *obj)
 {

Misc/stable_abi.toml

@@ -1567,8 +1567,9 @@ static PyObject *
 builtin_delattr_impl(PyObject *module, PyObject *obj, PyObject *name)
 /*[clinic end generated code: output=85134bc58dff79fa input=164865623abe7216]*/
 {
-    if (PyObject_SetAttr(obj, name, (PyObject *)NULL) != 0)
+    if (PyObject_DelAttr(obj, name) < 0) {
         return NULL;
+    }
     Py_RETURN_NONE;
 }
 

Objects/object.c

@@ -1240,7 +1240,7 @@ dummy_func(
 
         inst(DELETE_ATTR, (owner --)) {
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
-            int err = PyObject_SetAttr(owner, name, (PyObject *)NULL);
+            int err = PyObject_DelAttr(owner, name);
             DECREF_INPUTS();
             ERROR_IF(err, error);
         }