Close #17932: Fix an integer overflow issue on Windows 64-bit in iterators:

change the C type of seqiterobject.it_index from long to Py_ssize_t.

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.4.0 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #17932: Fix an integer overflow issue on Windows 64-bit in iterators:
+  change the C type of seqiterobject.it_index from long to Py_ssize_t.
+
 - Issue #18065: Don't set __path__ to the package name for frozen packages.
 
 - Issue #18088: When reloading a module, unconditionally reset all relevant

Objects/iterobject.c

@@ -4,7 +4,7 @@
 
 typedef struct {
     PyObject_HEAD
-    long      it_index;
+    Py_ssize_t it_index;
     PyObject *it_seq; /* Set to NULL when iterator is exhausted */
 } seqiterobject;