commit a96b0d119d586b16f2b17fc36f49c44a5dde162d
author Mark Dickinson <mdickinson@enthought.com> Sat Sep 24 09:01:16 2011 +0100
committer Mark Dickinson <mdickinson@enthought.com> Sat Sep 24 09:01:16 2011 +0100
tree 66d81b2309b6a05f6a140a4c33c08f00fee9b15c
parent 63c22fac727a72f0a4da8f72b12cd5f9b480376b

Backport issue #12973 itertools fix from 3.x.

Modules/itertoolsmodule.c

diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index ff25335..b51ccf9 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -1234,7 +1234,9 @@
         return NULL;
     lz->cnt++;
     oldnext = lz->next;
-    lz->next += lz->step;
+    /* The (size_t) cast below avoids the danger of undefined
+       behaviour from signed integer overflow. */
+    lz->next += (size_t)lz->step;
     if (lz->next < oldnext || (stop != -1 && lz->next > stop))
         lz->next = stop;
     return item;