1 files changed, 21 insertions, 1 deletions
diff --git a/Python/ceval.c b/Python/ceval.c
index 0983651..cea503e 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4689,7 +4689,7 @@ ext_call_fail:
 int
 _PyEval_SliceIndex(PyObject *v, Py_ssize_t *pi)
 {
-    if (v != NULL) {
+    if (v != NULL && v != Py_None) {
         Py_ssize_t x;
         if (PyInt_Check(v)) {
             /* XXX(nnorwitz): I think PyInt_AS_LONG is correct,
@@ -4714,6 +4714,26 @@ _PyEval_SliceIndex(PyObject *v, Py_ssize_t *pi)
     return 1;
 }
 
+int
+_PyEval_SliceIndexNotNone(PyObject *v, Py_ssize_t *pi)
+{
+    Py_ssize_t x;
+    if (PyIndex_Check(v)) {
+        x = PyNumber_AsSsize_t(v, NULL);
+        if (x == -1 && PyErr_Occurred())
+            return 0;
+    }
+    else {
+        PyErr_SetString(PyExc_TypeError,
+                        "slice indices must be integers or "
+                        "have an __index__ method");
+        return 0;
+    }
+    *pi = x;
+    return 1;
+}
+
+
 #undef ISINDEX
 #define ISINDEX(x) ((x) == NULL || \
                     PyInt_Check(x) || PyLong_Check(x) || PyIndex_Check(x))