Defer deleted item decref until after the deque is restored to a consistent state.
diff --git a/Misc/NEWS b/Misc/NEWS
index c52ad72..9eaaf58 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -45,6 +45,10 @@
- Issues #24099, #24100, and #24101: Fix free-after-use bug in heapq's siftup
and siftdown functions.
+- Backport collections.deque fixes from Python 3.5. Prevents reentrant badness
+ during deletion by deferring the decref until the container has been restored
+ to a consistent state.
+
- Issue #23008: Fixed resolving attributes with boolean value is False in pydoc.
- Fix asyncio issue 235: LifoQueue and PriorityQueue's put didn't
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index c1aa9a3..627fad5 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -698,9 +698,9 @@
if (cmp > 0) {
PyObject *tgt = deque_popleft(deque, NULL);
assert (tgt != NULL);
- Py_DECREF(tgt);
- if (_deque_rotate(deque, i) == -1)
+ if (_deque_rotate(deque, i))
return NULL;
+ Py_DECREF(tgt);
Py_RETURN_NONE;
}
else if (cmp < 0) {
@@ -781,16 +781,16 @@
deque_del_item(dequeobject *deque, Py_ssize_t i)
{
PyObject *item;
+ int rv;
assert (i >= 0 && i < Py_SIZE(deque));
- if (_deque_rotate(deque, -i) == -1)
+ if (_deque_rotate(deque, -i))
return -1;
-
item = deque_popleft(deque, NULL);
+ rv = _deque_rotate(deque, i);
assert (item != NULL);
Py_DECREF(item);
-
- return _deque_rotate(deque, i);
+ return rv;
}
static int