Issue #20440: Cleaning up the code by using Py_SETREF and Py_CLEAR.

Old code is correct, but with Py_SETREF and Py_CLEAR it can be cleaner.
This patch doesn't fix bugs and hence there is no need to backport it.

3 files changed, 5 insertions, 23 deletions

diff --git a/Objects/listobject.c b/Objects/listobject.c
index eee7c68e9e..fcc21cbebe 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -216,7 +216,6 @@ int
 PyList_SetItem(PyObject *op, Py_ssize_t i,
                PyObject *newitem)
 {
-    PyObject *olditem;
     PyObject **p;
     if (!PyList_Check(op)) {
         Py_XDECREF(newitem);
@@ -230,9 +229,7 @@ PyList_SetItem(PyObject *op, Py_ssize_t i,
         return -1;
     }
     p = ((PyListObject *)op) -> ob_item + i;
-    olditem = *p;
-    *p = newitem;
-    Py_XDECREF(olditem);
+    Py_SETREF(*p, newitem);
     return 0;
 }
 
@@ -730,7 +727,6 @@ list_inplace_repeat(PyListObject *self, Py_ssize_t n)
 static int
 list_ass_item(PyListObject *a, Py_ssize_t i, PyObject *v)
 {
-    PyObject *old_value;
     if (i < 0 || i >= Py_SIZE(a)) {
         PyErr_SetString(PyExc_IndexError,
                         "list assignment index out of range");
@@ -739,9 +735,7 @@ list_ass_item(PyListObject *a, Py_ssize_t i, PyObject *v)
     if (v == NULL)
         return list_ass_slice(a, i, i+1, v);
     Py_INCREF(v);
-    old_value = a->ob_item[i];
-    a->ob_item[i] = v;
-    Py_DECREF(old_value);
+    Py_SETREF(a->ob_item[i], v);
     return 0;
 }
 
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 7efa1a6776..8e1b00b63d 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -149,7 +149,6 @@ PyTuple_GetItem(PyObject *op, Py_ssize_t i)
 int
 PyTuple_SetItem(PyObject *op, Py_ssize_t i, PyObject *newitem)
 {
-    PyObject *olditem;
     PyObject **p;
     if (!PyTuple_Check(op) || op->ob_refcnt != 1) {
         Py_XDECREF(newitem);
@@ -163,9 +162,7 @@ PyTuple_SetItem(PyObject *op, Py_ssize_t i, PyObject *newitem)
         return -1;
     }
     p = ((PyTupleObject *)op) -> ob_item + i;
-    olditem = *p;
-    *p = newitem;
-    Py_XDECREF(olditem);
+    Py_SETREF(*p, newitem);
     return 0;
 }
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 4fac9e889b..78ef6acb13 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -401,7 +401,6 @@ type_qualname(PyTypeObject *type, void *context)
 static int
 type_set_name(PyTypeObject *type, PyObject *value, void *context)
 {
-    PyHeapTypeObject* et;
     char *tp_name;
     PyObject *tmp;
 
@@ -430,17 +429,9 @@ type_set_name(PyTypeObject *type, PyObject *value, void *context)
     if (tp_name == NULL)
         return -1;
 
-    et = (PyHeapTypeObject*)type;
-
-    Py_INCREF(value);
-
-    /* Wait until et is a sane state before Py_DECREF'ing the old et->ht_name
-       value.  (Bug #16447.)  */
-    tmp = et->ht_name;
-    et->ht_name = value;
-
     type->tp_name = tp_name;
-    Py_DECREF(tmp);
+    Py_INCREF(value);
+    Py_SETREF(((PyHeapTypeObject*)type)->ht_name, value);
 
     return 0;
 }