Added region check to tuple object (#46)

As far as I can see in the source code, tuples are always created
in the local region (effectively), and get their arguments before
they are assigned anywhere. So the only check added to set_item
should always succeed. Leaving optimising this case for future work.

Author: TobiasWrigstad

Objects/tupleobject.c

@@ -124,6 +124,14 @@ PyTuple_SetItem(PyObject *op, Py_ssize_t i, PyObject *newitem)
         return -1;
     }
 
+    // TODO: Pyrona: Possibly optimise this case as tuples
+    // should always be in local when they are assigned.
+    if (!Py_REGIONADDREFERENCE(op, newitem)){
+        Py_XDECREF(newitem);
+        // Error set by region add test
+        return -1;
+    }
+
     if (i < 0 || i >= Py_SIZE(op)) {
         Py_XDECREF(newitem);
         PyErr_SetString(PyExc_IndexError,