Re-enable __index__ for Py_ssize_t, fix refcount error in that function

Cython/Compiler/Nodes.py

@@ -2934,7 +2934,14 @@ utility_function_predeclarations = \
 typedef struct {PyObject **p; char *s;} __Pyx_InternTabEntry; /*proto*/
 typedef struct {PyObject **p; char *s; long n; int is_unicode;} __Pyx_StringTabEntry; /*proto*/
 
-#define __pyx_PyIndex_AsSsize_t(b) PyInt_AsSsize_t(PyNumber_Index(b))
+static INLINE Py_ssize_t __pyx_PyIndex_AsSsize_t(PyObject* b) {
+  Py_ssize_t ival;
+  PyObject* x = PyNumber_Index(b);
+  if (!x) return -1;
+  ival = PyInt_AsSsize_t(x);
+  Py_DECREF(x);
+  return ival;
+}
 
 #define __Pyx_PyBool_FromLong(b) ((b) ? (Py_INCREF(Py_True), Py_True) : (Py_INCREF(Py_False), Py_False))
 static INLINE int __Pyx_PyObject_IsTrue(PyObject* x) {

Cython/Compiler/PyrexTypes.py

@@ -417,7 +417,7 @@ class CULongLongType(CUIntType):
 class CPySSizeTType(CIntType):
 
     to_py_function = "PyInt_FromSsize_t"
-    from_py_function = "PyInt_AsSsize_t"
+    from_py_function = "__pyx_PyIndex_AsSsize_t"
 
 
 class CFloatType(CNumericType):