Make first raise argument optional

Grammar/Grammar

@@ -40,7 +40,7 @@ flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt
 break_stmt: 'break'
 continue_stmt: 'continue'
 return_stmt: 'return' [testlist]
-raise_stmt: 'raise' test [',' test [',' test]]
+raise_stmt: 'raise' [test [',' test [',' test]]]
 import_stmt: 'import' dotted_name (',' dotted_name)* | 'from' dotted_name 'import' ('*' | NAME (',' NAME)*)
 dotted_name: NAME ('.' NAME)*
 global_stmt: 'global' NAME (',' NAME)*

Python/ceval.c

@@ -1090,6 +1090,7 @@ eval_code2(co, globals, locals,
 				/* Fallthrough */
 			case 1:
 				w = POP(); /* exc */
+			case 0: /* Fallthrough */
 				why = do_raise(w, v, u);
 				break;
 			default:
@@ -1967,6 +1968,17 @@ static enum why_code
 do_raise(type, value, tb)
 	PyObject *type, *value, *tb;
 {
+	if (type == NULL) {
+		/* Reraise */
+		PyThreadState *tstate = PyThreadState_Get();
+		type = tstate->exc_type == NULL ? Py_None : tstate->exc_type;
+		value = tstate->exc_value;
+		tb = tstate->exc_traceback;
+		Py_XINCREF(type);
+		Py_XINCREF(value);
+		Py_XINCREF(tb);
+	}
+		
 	/* We support the following forms of raise:
 	   raise <class>, <classinstance>
 	   raise <class>, <argument tuple>

Python/compile.c

@@ -659,6 +659,8 @@ com_add(c, list, v)
 {
 	int n = PyList_Size(list);
 	int i;
+	/* XXX This is quadratic in the number of names per compilation unit.
+	   XXX Should use a dictionary. */
 	for (i = n; --i >= 0; ) {
 		PyObject *w = PyList_GetItem(list, i);
 		if (v->ob_type == w->ob_type && PyObject_Compare(v, w) == 0)
@@ -2050,13 +2052,15 @@ com_raise_stmt(c, n)
 	node *n;
 {
 	int i;
-	REQ(n, raise_stmt); /* 'raise' test [',' test [',' test]] */
+	REQ(n, raise_stmt); /* 'raise' [test [',' test [',' test]]] */
+	if (NCH(n) > 1) {
 		com_node(c, CHILD(n, 1));
 		if (NCH(n) > 3) {
 			com_node(c, CHILD(n, 3));
 			if (NCH(n) > 5)
 				com_node(c, CHILD(n, 5));
 		}
+	}
 	i = NCH(n)/2;
 	com_addoparg(c, RAISE_VARARGS, i);
 	com_pop(c, i);

Python/graminit.c

@@ -331,8 +331,9 @@ static state states_18[3] = {
 static arc arcs_19_0[1] = {
 	{48, 1},
 };
-static arc arcs_19_1[1] = {
+static arc arcs_19_1[2] = {
 	{21, 2},
+	{0, 1},
 };
 static arc arcs_19_2[2] = {
 	{22, 3},
@@ -353,7 +354,7 @@ static arc arcs_19_6[1] = {
 };
 static state states_19[7] = {
 	{1, arcs_19_0},
-	{1, arcs_19_1},
+	{2, arcs_19_1},
 	{2, arcs_19_2},
 	{1, arcs_19_3},
 	{2, arcs_19_4},