Regarding the patch below, isn't most of this redundant? ISTM that simply calling PyErr_SetString(...) should do all of this, including the exception chaining.


diff -r 23ab1197df0b Objects/genobject.c
--- a/Objects/genobject.c	Wed Nov 19 13:21:40 2014 +0200
+++ b/Objects/genobject.c	Thu Nov 20 16:47:59 2014 +1100
@@ -130,6 +130,23 @@
         }
         Py_CLEAR(result);
     }
+    else if (!result)
+    {
+        if (PyErr_ExceptionMatches(PyExc_StopIteration))
+        {
+            PyObject *exc, *val, *val2, *tb;
+            PyErr_Fetch(&exc, &val, &tb);
+            PyErr_NormalizeException(&exc, &val, &tb);
+            Py_DECREF(exc);
+            Py_XDECREF(tb);
+            PyErr_SetString(PyExc_RuntimeError,
+                "generator raised StopIteration");
+            PyErr_Fetch(&exc, &val2, &tb);
+            PyErr_NormalizeException(&exc, &val2, &tb);
+            PyException_SetContext(val2, val);
+            PyErr_Restore(exc, val2, tb);
+        }
+    }
 
     if (!result || f->f_stacktop == NULL) {
         /* generator can't be rerun, so release the frame */