SF patch #1200051: Small optimization for PyDict_Merge()
(Contributed by Barry Warsaw and Matt Messier.)
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 1be3477..aaca5aa 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1203,6 +1203,12 @@
if (other == mp || other->ma_used == 0)
/* a.update(a) or a.update({}); nothing to do */
return 0;
+ if (mp->ma_used == 0)
+ /* Since the target dict is empty, PyDict_GetItem()
+ * always returns NULL. Setting override to 1
+ * skips the unnecessary test.
+ */
+ override = 1;
/* Do one big resize at the start, rather than
* incrementally resizing as we insert new items. Expect
* that there will be no (or few) overlapping keys.