Index: Include/Python-ast.h
===================================================================
--- Include/Python-ast.h	(revision 42949)
+++ Include/Python-ast.h	(working copy)
@@ -1,4 +1,4 @@
-/* File automatically generated by Parser/asdl_c.py */
+/* File automatically generated by Parser\asdl_c.py */
 
 #include "asdl.h"
 
@@ -300,6 +300,7 @@
                         expr_ty lower;
                         expr_ty upper;
                         expr_ty step;
+                        bool ext;
                 } Slice;
                 
                 struct {
@@ -422,7 +423,8 @@
 expr_ty Tuple(asdl_seq * elts, expr_context_ty ctx, int lineno, int col_offset,
               PyArena *arena);
 slice_ty Ellipsis(PyArena *arena);
-slice_ty Slice(expr_ty lower, expr_ty upper, expr_ty step, PyArena *arena);
+slice_ty Slice(expr_ty lower, expr_ty upper, expr_ty step, bool ext, PyArena
+               *arena);
 slice_ty ExtSlice(asdl_seq * dims, PyArena *arena);
 slice_ty Index(expr_ty value, PyArena *arena);
 comprehension_ty comprehension(expr_ty target, expr_ty iter, asdl_seq * ifs,
Index: Lib/test/test_ast.py
===================================================================
--- Lib/test/test_ast.py	(revision 42949)
+++ Lib/test/test_ast.py	(working copy)
@@ -152,7 +152,8 @@
             assert to_tuple(ast_tree) == o
             test_order(ast_tree, (0, 0))
 
-#### EVERYTHING BELOW IS GENERATED #####
+#### EVERYTHING BELOW IS GENERATED.  TO REGENERATE, EXECUTE THIS FILE #####
+#### WITH THE '-g' COMMAND LINE FLAG AND PASTE THE RESULTS.           #####
 exec_results = [
 ('Module', [('FunctionDef', (1, 0), 'f', ('arguments', [], None, None, []), [('Pass', (1, 9))], [])]),
 ('Module', [('ClassDef', (1, 0), 'C', [], [('Pass', (1, 8))])]),
@@ -194,10 +195,10 @@
 ('Expression', ('Num', (1, 0), 10L)),
 ('Expression', ('Str', (1, 0), 'string')),
 ('Expression', ('Attribute', (1, 0), ('Name', (1, 0), 'a', ('Load',)), 'b', ('Load',))),
-('Expression', ('Subscript', (1, 0), ('Name', (1, 0), 'a', ('Load',)), ('Slice', ('Name', (1, 2), 'b', ('Load',)), ('Name', (1, 4), 'c', ('Load',)), None), ('Load',))),
+('Expression', ('Subscript', (1, 0), ('Name', (1, 0), 'a', ('Load',)), ('Slice', ('Name', (1, 2), 'b', ('Load',)), ('Name', (1, 4), 'c', ('Load',)), None, False), ('Load',))),
 ('Expression', ('Name', (1, 0), 'v', ('Load',))),
 ('Expression', ('List', (1, 0), [('Num', (1, 1), 1), ('Num', (1, 3), 2), ('Num', (1, 5), 3)], ('Load',))),
 ('Expression', ('Tuple', (1, 0), [('Num', (1, 0), 1), ('Num', (1, 2), 2), ('Num', (1, 4), 3)], ('Load',))),
-('Expression', ('Call', (1, 0), ('Attribute', (1, 0), ('Attribute', (1, 0), ('Attribute', (1, 0), ('Name', (1, 0), 'a', ('Load',)), 'b', ('Load',)), 'c', ('Load',)), 'd', ('Load',)), [('Subscript', (1, 8), ('Attribute', (1, 8), ('Name', (1, 8), 'a', ('Load',)), 'b', ('Load',)), ('Slice', ('Num', (1, 12), 1), ('Num', (1, 14), 2), None), ('Load',))], [], None, None)),
+('Expression', ('Call', (1, 0), ('Attribute', (1, 0), ('Attribute', (1, 0), ('Attribute', (1, 0), ('Name', (1, 0), 'a', ('Load',)), 'b', ('Load',)), 'c', ('Load',)), 'd', ('Load',)), [('Subscript', (1, 8), ('Attribute', (1, 8), ('Name', (1, 8), 'a', ('Load',)), 'b', ('Load',)), ('Slice', ('Num', (1, 12), 1), ('Num', (1, 14), 2), None, False), ('Load',))], [], None, None)),
 ]
 run_tests()
Index: Parser/Python.asdl
===================================================================
--- Parser/Python.asdl	(revision 42949)
+++ Parser/Python.asdl	(working copy)
@@ -82,7 +82,7 @@
 
 	expr_context = Load | Store | Del | AugLoad | AugStore | Param
 
-	slice = Ellipsis | Slice(expr? lower, expr? upper, expr? step) 
+	slice = Ellipsis | Slice(expr? lower, expr? upper, expr? step, bool ext)
 	      | ExtSlice(slice* dims) 
 	      | Index(expr value) 
 
Index: Python/ast.c
===================================================================
--- Python/ast.c	(revision 42949)
+++ Python/ast.c	(working copy)
@@ -1318,9 +1318,12 @@
     ch = CHILD(n, NCH(n) - 1);
     if (TYPE(ch) == sliceop) {
 	if (NCH(ch) == 1)
+	{
             /* XXX: If only 1 child, then should just be a colon.  Should we
                just skip assigning and just get to the return? */
 	    ch = CHILD(ch, 0);
+		return Slice(lower, upper, step, 1, c->c_arena);
+	}
 	else
 	    ch = CHILD(ch, 1);
 	if (TYPE(ch) == test) {
@@ -1330,7 +1333,7 @@
         }
     }
 
-    return Slice(lower, upper, step, c->c_arena);
+    return Slice(lower, upper, step, 0, c->c_arena);
 }
 
 static expr_ty
Index: Python/compile.c
===================================================================
--- Python/compile.c	(revision 42949)
+++ Python/compile.c	(working copy)
@@ -3773,6 +3773,9 @@
 	if (s->v.Slice.step) {
 		n++;
 		VISIT(c, expr, s->v.Slice.step);
+	} else if (s->v.Slice.ext) {
+		n++;
+		ADDOP_O(c, LOAD_CONST, Py_None, consts);
 	}
 	ADDOP_I(c, BUILD_SLICE, n);
 	return 1;
@@ -3860,7 +3863,7 @@
 		ADDOP_O(c, LOAD_CONST, Py_Ellipsis, consts);
 		break;
 	case Slice_kind:
-		if (!s->v.Slice.step) 
+		if (!s->v.Slice.step && !s->v.Slice.ext && s->kind == Slice_kind) 
 			return compiler_simple_slice(c, s, ctx);
 		if (!compiler_slice(c, s, ctx))
 			return 0;
Index: Python/Python-ast.c
===================================================================
--- Python/Python-ast.c	(revision 42949)
+++ Python/Python-ast.c	(working copy)
@@ -1,4 +1,4 @@
-/* File automatically generated by Parser/asdl_c.py */
+/* File automatically generated by Parser\asdl_c.py */
 
 #include "Python.h"
 #include "Python-ast.h"
@@ -263,6 +263,7 @@
         "lower",
         "upper",
         "step",
+        "ext",
 };
 static PyTypeObject *ExtSlice_type;
 static char *ExtSlice_fields[]={
@@ -576,7 +577,7 @@
         if (!add_attributes(slice_type, NULL, 0)) return 0;
         Ellipsis_type = make_type("Ellipsis", slice_type, NULL, 0);
         if (!Ellipsis_type) return 0;
-        Slice_type = make_type("Slice", slice_type, Slice_fields, 3);
+        Slice_type = make_type("Slice", slice_type, Slice_fields, 4);
         if (!Slice_type) return 0;
         ExtSlice_type = make_type("ExtSlice", slice_type, ExtSlice_fields, 1);
         if (!ExtSlice_type) return 0;
@@ -1767,7 +1768,7 @@
 }
 
 slice_ty
-Slice(expr_ty lower, expr_ty upper, expr_ty step, PyArena *arena)
+Slice(expr_ty lower, expr_ty upper, expr_ty step, bool ext, PyArena *arena)
 {
         slice_ty p;
         p = (slice_ty)PyArena_Malloc(arena, sizeof(*p));
@@ -1779,6 +1780,7 @@
         p->v.Slice.lower = lower;
         p->v.Slice.upper = upper;
         p->v.Slice.step = step;
+        p->v.Slice.ext = ext;
         return p;
 }
 
@@ -2719,6 +2721,11 @@
                 if (PyObject_SetAttrString(result, "step", value) == -1)
                         goto failed;
                 Py_DECREF(value);
+                value = ast2obj_bool(o->v.Slice.ext);
+                if (!value) goto failed;
+                if (PyObject_SetAttrString(result, "ext", value) == -1)
+                        goto failed;
+                Py_DECREF(value);
                 break;
         case ExtSlice_kind:
                 result = PyType_GenericNew(ExtSlice_type, NULL, NULL);