Issue 16398: Add assertions to show why memcmp is safe.
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index e0c6f0c..17b1ad6 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -425,8 +425,9 @@
else if (n < -halflen)
n += len;
}
-
assert(deque->len > 1);
+ assert((n < len / 2) || (n > len / -2));
+
deque->state++;
for (i=0 ; i<n ; ) {
if (deque->leftindex == 0) {
@@ -446,6 +447,8 @@
if (m > deque->leftindex)
m = deque->leftindex;
assert (m > 0);
+ assert (deque->leftblock != deque->rightblock ||
+ deque->leftindex < deque->rightindex - m + 1);
memcpy(&deque->leftblock->data[deque->leftindex - m],
&deque->rightblock->data[deque->rightindex - m + 1],
m * sizeof(PyObject *));