bpo-35441: Remove dead and buggy code related to PyList_SetItem(). (GH-11033)

In _localemodule.c and selectmodule.c, remove dead code that would
cause double decrefs if run.

In addition, replace PyList_SetItem() with PyList_SET_ITEM() in cases
where a new list is populated and there is no possibility of an error.

In addition, check if the list changed size in the loop in array_array_fromlist().

1 files changed, 2 insertions, 8 deletions

diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index fe69cd58dc6..7f62ab111d1 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -693,10 +693,7 @@ select_poll_poll_impl(pollObject *self, PyObject *timeout_obj)
             goto error;
         }
         PyTuple_SET_ITEM(value, 1, num);
-        if ((PyList_SetItem(result_list, j, value)) == -1) {
-            Py_DECREF(value);
-            goto error;
-        }
+        PyList_SET_ITEM(result_list, j, value);
         i++;
     }
     return result_list;
@@ -986,10 +983,7 @@ select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
         Py_DECREF(num2);
         if (value == NULL)
             goto error;
-        if ((PyList_SetItem(result_list, i, value)) == -1) {
-            Py_DECREF(value);
-            goto error;
-        }
+        PyList_SET_ITEM(result_list, i, value);
     }
 
     return result_list;