Only update the arr variable when PyObject_RichCompareBool() has been called.

rhettinger · rhettinger · commit 2300bf29e69e · 2015-12-07T20:45:16.000-08:00
diff --git a/Modules/_heapqmodule.c b/Modules/_heapqmodule.c
@@ -78,14 +78,14 @@ siftup(PyListObject *heap, Py_ssize_t pos)
             if (cmp < 0)
                 return -1;
             childpos += ((unsigned)cmp ^ 1);   /* increment when cmp==0 */
+            arr = _PyList_ITEMS(heap);         /* arr may have changed */
             if (endpos != PyList_GET_SIZE(heap)) {
                 PyErr_SetString(PyExc_RuntimeError,
                                 "list changed size during iteration");
                 return -1;
             }
         }
         /* Move the smaller child up. */
-        arr = _PyList_ITEMS(heap);
         tmp1 = arr[childpos];
         tmp2 = arr[pos];
         arr[childpos] = tmp2;
@@ -432,14 +432,14 @@ siftup_max(PyListObject *heap, Py_ssize_t pos)
             if (cmp < 0)
                 return -1;
             childpos += ((unsigned)cmp ^ 1);   /* increment when cmp==0 */
+            arr = _PyList_ITEMS(heap);         /* arr may have changed */
             if (endpos != PyList_GET_SIZE(heap)) {
                 PyErr_SetString(PyExc_RuntimeError,
                                 "list changed size during iteration");
                 return -1;
             }
         }
         /* Move the smaller child up. */
-        arr = _PyList_ITEMS(heap);
         tmp1 = arr[childpos];
         tmp2 = arr[pos];
         arr[childpos] = tmp2;
