bpo-29935: Fixed error messages in the index() method of tuple, list and deque (#887) (#907)

when pass indices of wrong type.
(cherry picked from commit d4edfc9)

Author: serhiy-storchaka

Include/ceval.h

@@ -216,6 +216,7 @@ PyAPI_FUNC(Py_ssize_t) _PyEval_RequestCodeExtraIndex(freefunc);
 
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(int) _PyEval_SliceIndex(PyObject *, Py_ssize_t *);
+PyAPI_FUNC(int) _PyEval_SliceIndexNotNone(PyObject *, Py_ssize_t *);
 PyAPI_FUNC(void) _PyEval_SignalAsyncExc(void);
 #endif
 

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.6.2 release candidate 1?
 Core and Builtins
 -----------------
 
+- bpo-29935: Fixed error messages in the index() method of tuple, list and deque
+  when pass indices of wrong type.
+
 - bpo-29859: Show correct error messages when any of the pthread_* calls in
   thread_pthread.h fails.
 

Modules/_collectionsmodule.c

@@ -1051,8 +1051,8 @@ deque_index(dequeobject *deque, PyObject *args)
     int cmp;
 
     if (!PyArg_ParseTuple(args, "O|O&O&:index", &v,
-                                _PyEval_SliceIndex, &start,
-                                _PyEval_SliceIndex, &stop))
+                                _PyEval_SliceIndexNotNone, &start,
+                                _PyEval_SliceIndexNotNone, &stop))
         return NULL;
     if (start < 0) {
         start += Py_SIZE(deque);

Objects/listobject.c

@@ -2153,8 +2153,8 @@ listindex(PyListObject *self, PyObject *args)
     PyObject *v;
 
     if (!PyArg_ParseTuple(args, "O|O&O&:index", &v,
-                                _PyEval_SliceIndex, &start,
-                                _PyEval_SliceIndex, &stop))
+                                _PyEval_SliceIndexNotNone, &start,
+                                _PyEval_SliceIndexNotNone, &stop))
         return NULL;
     if (start < 0) {
         start += Py_SIZE(self);

Objects/tupleobject.c

@@ -522,8 +522,8 @@ tupleindex(PyTupleObject *self, PyObject *args)
     PyObject *v;
 
     if (!PyArg_ParseTuple(args, "O|O&O&:index", &v,
-                                _PyEval_SliceIndex, &start,
-                                _PyEval_SliceIndex, &stop))
+                                _PyEval_SliceIndexNotNone, &start,
+                                _PyEval_SliceIndexNotNone, &stop))
         return NULL;
     if (start < 0) {
         start += Py_SIZE(self);

Python/ceval.c

@@ -5074,14 +5074,10 @@ do_call_core(PyObject *func, PyObject *callargs, PyObject *kwdict)
    and silently boost values less than -PY_SSIZE_T_MAX-1 to -PY_SSIZE_T_MAX-1.
    Return 0 on error, 1 on success.
 */
-/* Note:  If v is NULL, return success without storing into *pi.  This
-   is because_PyEval_SliceIndex() is called by apply_slice(), which can be
-   called by the SLICE opcode with v and/or w equal to NULL.
-*/
 int
 _PyEval_SliceIndex(PyObject *v, Py_ssize_t *pi)
 {
-    if (v != NULL) {
+    if (v != Py_None) {
         Py_ssize_t x;
         if (PyIndex_Check(v)) {
             x = PyNumber_AsSsize_t(v, NULL);
@@ -5099,6 +5095,26 @@ _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;
+}
+
+
 #define CANNOT_CATCH_MSG "catching classes that do not inherit from "\
                          "BaseException is not allowed"