Issue #1066: implement PEP 3109, 2/3 of PEP 3134.

7 files changed, 113 insertions, 178 deletions

diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 605a152..9089b9a 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -2,7 +2,7 @@
 
 
 /*
-   __version__ 56266.
+   __version__ 465.
 
    This module must be committed separately after each AST grammar change;
    The __version__ number is set to the revision number of the commit
@@ -101,9 +101,8 @@ static char *With_fields[]={
 };
 static PyTypeObject *Raise_type;
 static char *Raise_fields[]={
-        "type",
-        "inst",
-        "tback",
+        "exc",
+        "cause",
 };
 static PyTypeObject *TryExcept_type;
 static char *TryExcept_fields[]={
@@ -510,7 +509,7 @@ static int init_types(void)
         if (!If_type) return 0;
         With_type = make_type("With", stmt_type, With_fields, 3);
         if (!With_type) return 0;
-        Raise_type = make_type("Raise", stmt_type, Raise_fields, 3);
+        Raise_type = make_type("Raise", stmt_type, Raise_fields, 2);
         if (!Raise_type) return 0;
         TryExcept_type = make_type("TryExcept", stmt_type, TryExcept_fields, 3);
         if (!TryExcept_type) return 0;
@@ -1052,17 +1051,15 @@ With(expr_ty context_expr, expr_ty optional_vars, asdl_seq * body, int lineno,
 }
 
 stmt_ty
-Raise(expr_ty type, expr_ty inst, expr_ty tback, int lineno, int col_offset,
-      PyArena *arena)
+Raise(expr_ty exc, expr_ty cause, int lineno, int col_offset, PyArena *arena)
 {
         stmt_ty p;
         p = (stmt_ty)PyArena_Malloc(arena, sizeof(*p));
         if (!p)
                 return NULL;
         p->kind = Raise_kind;
-        p->v.Raise.type = type;
-        p->v.Raise.inst = inst;
-        p->v.Raise.tback = tback;
+        p->v.Raise.exc = exc;
+        p->v.Raise.cause = cause;
         p->lineno = lineno;
         p->col_offset = col_offset;
         return p;
@@ -2221,19 +2218,14 @@ ast2obj_stmt(void* _o)
         case Raise_kind:
                 result = PyType_GenericNew(Raise_type, NULL, NULL);
                 if (!result) goto failed;
-                value = ast2obj_expr(o->v.Raise.type);
-                if (!value) goto failed;
-                if (PyObject_SetAttrString(result, "type", value) == -1)
-                        goto failed;
-                Py_DECREF(value);
-                value = ast2obj_expr(o->v.Raise.inst);
+                value = ast2obj_expr(o->v.Raise.exc);
                 if (!value) goto failed;
-                if (PyObject_SetAttrString(result, "inst", value) == -1)
+                if (PyObject_SetAttrString(result, "exc", value) == -1)
                         goto failed;
                 Py_DECREF(value);
-                value = ast2obj_expr(o->v.Raise.tback);
+                value = ast2obj_expr(o->v.Raise.cause);
                 if (!value) goto failed;
-                if (PyObject_SetAttrString(result, "tback", value) == -1)
+                if (PyObject_SetAttrString(result, "cause", value) == -1)
                         goto failed;
                 Py_DECREF(value);
                 break;
@@ -3179,7 +3171,7 @@ init_ast(void)
         if (PyDict_SetItemString(d, "AST", (PyObject*)AST_type) < 0) return;
         if (PyModule_AddIntConstant(m, "PyCF_ONLY_AST", PyCF_ONLY_AST) < 0)
                 return;
-        if (PyModule_AddStringConstant(m, "__version__", "56266") < 0)
+        if (PyModule_AddStringConstant(m, "__version__", "465") < 0)
                 return;
         if (PyDict_SetItemString(d, "mod", (PyObject*)mod_type) < 0) return;
         if (PyDict_SetItemString(d, "Module", (PyObject*)Module_type) < 0)
diff --git a/Python/ast.c b/Python/ast.c
index c13d093..8dd3c4ab 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -2199,39 +2199,18 @@ ast_for_flow_stmt(struct compiling *c, const node *n)
             }
         case raise_stmt:
             if (NCH(ch) == 1)
-                return Raise(NULL, NULL, NULL, LINENO(n), n->n_col_offset, c->c_arena);
-            else if (NCH(ch) == 2) {
+                return Raise(NULL, NULL, LINENO(n), n->n_col_offset, c->c_arena);
+            else if (NCH(ch) >= 2) {
+                expr_ty cause = NULL;
                 expr_ty expression = ast_for_expr(c, CHILD(ch, 1));
                 if (!expression)
                     return NULL;
-                return Raise(expression, NULL, NULL, LINENO(n), n->n_col_offset, c->c_arena);
-            }
-            else if (NCH(ch) == 4) {
-                expr_ty expr1, expr2;
-
-                expr1 = ast_for_expr(c, CHILD(ch, 1));
-                if (!expr1)
-                    return NULL;
-                expr2 = ast_for_expr(c, CHILD(ch, 3));
-                if (!expr2)
-                    return NULL;
-
-                return Raise(expr1, expr2, NULL, LINENO(n), n->n_col_offset, c->c_arena);
-            }
-            else if (NCH(ch) == 6) {
-                expr_ty expr1, expr2, expr3;
-
-                expr1 = ast_for_expr(c, CHILD(ch, 1));
-                if (!expr1)
-                    return NULL;
-                expr2 = ast_for_expr(c, CHILD(ch, 3));
-                if (!expr2)
-                    return NULL;
-                expr3 = ast_for_expr(c, CHILD(ch, 5));
-                if (!expr3)
-                    return NULL;
-                    
-                return Raise(expr1, expr2, expr3, LINENO(n), n->n_col_offset, c->c_arena);
+                if (NCH(ch) == 4) {
+                    cause = ast_for_expr(c, CHILD(ch, 3));
+                    if (!cause)
+                        return NULL;
+                }
+                return Raise(expression, cause, LINENO(n), n->n_col_offset, c->c_arena);
             }
         default:
             PyErr_Format(PyExc_SystemError,
diff --git a/Python/ceval.c b/Python/ceval.c
index be804ad..24d4dec 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -484,7 +484,7 @@ enum why_code {
 		WHY_YIELD =	0x0040	/* 'yield' operator */
 };
 
-static enum why_code do_raise(PyObject *, PyObject *, PyObject *);
+static enum why_code do_raise(PyObject *, PyObject *);
 static int unpack_iterable(PyObject *, int, int, PyObject **);
 
 /* for manipulating the thread switch and periodic "stuff" - used to be
@@ -1465,18 +1465,14 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
 		default: switch (opcode) {
 #endif
 		case RAISE_VARARGS:
-			u = v = w = NULL;
+			v = w = NULL;
 			switch (oparg) {
-			case 3:
-				u = POP(); /* traceback */
-				/* Fallthrough */
-			case 2:
-				v = POP(); /* value */
-				/* Fallthrough */
+            case 2:
+                v = POP(); /* cause */
 			case 1:
 				w = POP(); /* exc */
 			case 0: /* Fallthrough */
-				why = do_raise(w, v, u);
+				why = do_raise(w, v);
 				break;
 			default:
 				PyErr_SetString(PyExc_SystemError,
@@ -2880,6 +2876,7 @@ set_exc_info(PyThreadState *tstate,
 	tstate->exc_type = type;
 	tstate->exc_value = value;
 	tstate->exc_traceback = tb;
+    PyException_SetTraceback(value, tb);
 	Py_XDECREF(tmp_type);
 	Py_XDECREF(tmp_value);
 	Py_XDECREF(tmp_tb);
@@ -2928,95 +2925,78 @@ reset_exc_info(PyThreadState *tstate)
 /* Logic for the raise statement (too complicated for inlining).
    This *consumes* a reference count to each of its arguments. */
 static enum why_code
-do_raise(PyObject *type, PyObject *value, PyObject *tb)
+do_raise(PyObject *exc, PyObject *cause)
 {
-	if (type == NULL) {
+    PyObject *type = NULL, *value = NULL, *tb = NULL;
+
+	if (exc == NULL) {
 		/* Reraise */
 		PyThreadState *tstate = PyThreadState_GET();
-		type = tstate->exc_type == NULL ? Py_None : tstate->exc_type;
+		type = tstate->exc_type;
 		value = tstate->exc_value;
 		tb = tstate->exc_traceback;
-		Py_XINCREF(type);
+        if (type == Py_None) {
+            PyErr_SetString(PyExc_RuntimeError,
+                                    "No active exception to reraise");
+            return WHY_EXCEPTION;
+        }
+        Py_XINCREF(type);
 		Py_XINCREF(value);
 		Py_XINCREF(tb);
+        PyErr_Restore(type, value, tb);
+        return WHY_RERAISE;
 	}
 
 	/* We support the following forms of raise:
-	   raise <class>, <classinstance>
-	   raise <class>, <argument tuple>
-	   raise <class>, None
-	   raise <class>, <argument>
-	   raise <classinstance>, None
-	   raise <string>, <object>
-	   raise <string>, None
-
-	   An omitted second argument is the same as None.
-
-	   In addition, raise <tuple>, <anything> is the same as
-	   raising the tuple's first item (and it better have one!);
-	   this rule is applied recursively.
-
-	   Finally, an optional third argument can be supplied, which
-	   gives the traceback to be substituted (useful when
-	   re-raising an exception after examining it).  */
-
-	/* First, check the traceback argument, replacing None with
-	   NULL. */
-	if (tb == Py_None) {
-		Py_DECREF(tb);
-		tb = NULL;
-	}
-	else if (tb != NULL && !PyTraceBack_Check(tb)) {
-		PyErr_SetString(PyExc_TypeError,
-			   "raise: arg 3 must be a traceback or None");
-		goto raise_error;
-	}
-
-	/* Next, replace a missing value with None */
-	if (value == NULL) {
-		value = Py_None;
-		Py_INCREF(value);
-	}
+	   raise
+       raise <instance>
+       raise <type> */
 
-	/* Next, repeatedly, replace a tuple exception with its first item */
-	while (PyTuple_Check(type) && PyTuple_Size(type) > 0) {
-		PyObject *tmp = type;
-		type = PyTuple_GET_ITEM(type, 0);
+	if (PyExceptionClass_Check(exc)) {
+        type = exc;
+        value = PyObject_CallObject(exc, NULL);
+		if (value == NULL)
+            goto raise_error;
+    }
+	else if (PyExceptionInstance_Check(exc)) {
+		value = exc;
+		type = PyExceptionInstance_Class(exc);
 		Py_INCREF(type);
-		Py_DECREF(tmp);
-	}
-
-	if (PyExceptionClass_Check(type))
-		PyErr_NormalizeException(&type, &value, &tb);
-
-	else if (PyExceptionInstance_Check(type)) {
-		/* Raising an instance.  The value should be a dummy. */
-		if (value != Py_None) {
-			PyErr_SetString(PyExc_TypeError,
-			  "instance exception may not have a separate value");
-			goto raise_error;
-		}
-		else {
-			/* Normalize to raise <class>, <instance> */
-			Py_DECREF(value);
-			value = type;
-			type = PyExceptionInstance_Class(type);
-			Py_INCREF(type);
-		}
 	}
 	else {
 		/* Not something you can raise.  You get an exception
 		   anyway, just not what you specified :-) */
+        Py_DECREF(exc);
+        Py_XDECREF(cause);
 		PyErr_SetString(PyExc_TypeError,
                                 "exceptions must derive from BaseException");
 		goto raise_error;
 	}
+
+    tb = PyException_GetTraceback(value);
+    if (cause) {
+        PyObject *fixed_cause;
+        if (PyExceptionClass_Check(cause)) {
+            fixed_cause = PyObject_CallObject(cause, NULL);
+            if (fixed_cause == NULL)
+                goto raise_error;
+        }
+        else if (PyExceptionInstance_Check(cause)) {
+            fixed_cause = cause;
+        }
+        else {
+            Py_DECREF(cause);
+            PyErr_SetString(PyExc_TypeError,
+                            "exception causes must derive from BaseException");
+            goto raise_error;
+        }
+        PyException_SetCause(value, fixed_cause);
+    }
+
 	PyErr_Restore(type, value, tb);
-	if (tb == NULL)
-		return WHY_EXCEPTION;
-	else
-		return WHY_RERAISE;
- raise_error:
+	return WHY_EXCEPTION;
+
+raise_error:
 	Py_XDECREF(value);
 	Py_XDECREF(type);
 	Py_XDECREF(tb);
diff --git a/Python/compile.c b/Python/compile.c
index 3a21127..e569102 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2187,11 +2187,9 @@ compiler_assert(struct compiler *c, stmt_ty s)
 	ADDOP_O(c, LOAD_GLOBAL, assertion_error, names);
 	if (s->v.Assert.msg) {
 		VISIT(c, expr, s->v.Assert.msg);
-		ADDOP_I(c, RAISE_VARARGS, 2);
-	}
-	else {
-		ADDOP_I(c, RAISE_VARARGS, 1);
+		ADDOP_I(c, CALL_FUNCTION, 1);
 	}
+	ADDOP_I(c, RAISE_VARARGS, 1);
 	compiler_use_next_block(c, end);
 	ADDOP(c, POP_TOP);
 	return 1;
@@ -2244,17 +2242,13 @@ compiler_visit_stmt(struct compiler *c, stmt_ty s)
 		return compiler_if(c, s);
 	case Raise_kind:
 		n = 0;
-		if (s->v.Raise.type) {
-			VISIT(c, expr, s->v.Raise.type);
+		if (s->v.Raise.exc) {
+			VISIT(c, expr, s->v.Raise.exc);
 			n++;
-			if (s->v.Raise.inst) {
-				VISIT(c, expr, s->v.Raise.inst);
-				n++;
-				if (s->v.Raise.tback) {
-					VISIT(c, expr, s->v.Raise.tback);
-					n++;
-				}
-			}
+            if (s->v.Raise.cause) {
+                VISIT(c, expr, s->v.Raise.cause);
+                n++;
+            }
 		}
 		ADDOP_I(c, RAISE_VARARGS, n);
 		break;
diff --git a/Python/graminit.c b/Python/graminit.c
index 95905d7..081a072 100644
--- a/Python/graminit.c
+++ b/Python/graminit.c
@@ -503,34 +503,25 @@ static arc arcs_24_1[2] = {
 	{0, 1},
 };
 static arc arcs_24_2[2] = {
-	{30, 3},
+	{71, 3},
 	{0, 2},
 };
 static arc arcs_24_3[1] = {
 	{24, 4},
 };
-static arc arcs_24_4[2] = {
-	{30, 5},
+static arc arcs_24_4[1] = {
 	{0, 4},
 };
-static arc arcs_24_5[1] = {
-	{24, 6},
-};
-static arc arcs_24_6[1] = {
-	{0, 6},
-};
-static state states_24[7] = {
+static state states_24[5] = {
 	{1, arcs_24_0},
 	{2, arcs_24_1},
 	{2, arcs_24_2},
 	{1, arcs_24_3},
-	{2, arcs_24_4},
-	{1, arcs_24_5},
-	{1, arcs_24_6},
+	{1, arcs_24_4},
 };
 static arc arcs_25_0[2] = {
-	{71, 1},
 	{72, 1},
+	{73, 1},
 };
 static arc arcs_25_1[1] = {
 	{0, 1},
@@ -540,10 +531,10 @@ static state states_25[2] = {
 	{1, arcs_25_1},
 };
 static arc arcs_26_0[1] = {
-	{73, 1},
+	{74, 1},
 };
 static arc arcs_26_1[1] = {
-	{74, 2},
+	{75, 2},
 };
 static arc arcs_26_2[1] = {
 	{0, 2},
@@ -554,7 +545,7 @@ static state states_26[3] = {
 	{1, arcs_26_2},
 };
 static arc arcs_27_0[1] = {
-	{75, 1},
+	{71, 1},
 };
 static arc arcs_27_1[3] = {
 	{76, 2},
@@ -565,10 +556,10 @@ static arc arcs_27_2[4] = {
 	{76, 2},
 	{77, 2},
 	{12, 3},
-	{73, 4},
+	{74, 4},
 };
 static arc arcs_27_3[1] = {
-	{73, 4},
+	{74, 4},
 };
 static arc arcs_27_4[3] = {
 	{31, 5},
@@ -1733,9 +1724,9 @@ static state states_80[3] = {
 };
 static dfa dfas[81] = {
 	{256, "single_input", 0, 3, states_0,
-	 "\004\050\060\200\000\000\000\050\170\052\034\144\011\040\004\000\200\041\224\017\101"},
+	 "\004\050\060\200\000\000\000\050\370\044\034\144\011\040\004\000\200\041\224\017\101"},
 	{257, "file_input", 0, 2, states_1,
-	 "\204\050\060\200\000\000\000\050\170\052\034\144\011\040\004\000\200\041\224\017\101"},
+	 "\204\050\060\200\000\000\000\050\370\044\034\144\011\040\004\000\200\041\224\017\101"},
 	{258, "eval_input", 0, 3, states_2,
 	 "\000\040\040\200\000\000\000\000\000\040\000\000\000\040\004\000\200\041\224\017\000"},
 	{259, "decorator", 0, 7, states_3,
@@ -1757,11 +1748,11 @@ static dfa dfas[81] = {
 	{267, "vfpdef", 0, 2, states_11,
 	 "\000\000\040\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
 	{268, "stmt", 0, 2, states_12,
-	 "\000\050\060\200\000\000\000\050\170\052\034\144\011\040\004\000\200\041\224\017\101"},
+	 "\000\050\060\200\000\000\000\050\370\044\034\144\011\040\004\000\200\041\224\017\101"},
 	{269, "simple_stmt", 0, 4, states_13,
-	 "\000\040\040\200\000\000\000\050\170\052\034\000\000\040\004\000\200\041\224\017\100"},
+	 "\000\040\040\200\000\000\000\050\370\044\034\000\000\040\004\000\200\041\224\017\100"},
 	{270, "small_stmt", 0, 2, states_14,
-	 "\000\040\040\200\000\000\000\050\170\052\034\000\000\040\004\000\200\041\224\017\100"},
+	 "\000\040\040\200\000\000\000\050\370\044\034\000\000\040\004\000\200\041\224\017\100"},
 	{271, "expr_stmt", 0, 6, states_15,
 	 "\000\040\040\200\000\000\000\000\000\040\000\000\000\040\004\000\200\041\224\017\000"},
 	{272, "augassign", 0, 2, states_16,
@@ -1780,14 +1771,14 @@ static dfa dfas[81] = {
 	 "\000\000\000\000\000\000\000\000\040\000\000\000\000\000\000\000\000\000\000\000\000"},
 	{279, "yield_stmt", 0, 2, states_23,
 	 "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\100"},
-	{280, "raise_stmt", 0, 7, states_24,
+	{280, "raise_stmt", 0, 5, states_24,
 	 "\000\000\000\000\000\000\000\000\100\000\000\000\000\000\000\000\000\000\000\000\000"},
 	{281, "import_stmt", 0, 2, states_25,
-	 "\000\000\000\000\000\000\000\000\000\012\000\000\000\000\000\000\000\000\000\000\000"},
+	 "\000\000\000\000\000\000\000\000\200\004\000\000\000\000\000\000\000\000\000\000\000"},
 	{282, "import_name", 0, 3, states_26,
-	 "\000\000\000\000\000\000\000\000\000\002\000\000\000\000\000\000\000\000\000\000\000"},
+	 "\000\000\000\000\000\000\000\000\000\004\000\000\000\000\000\000\000\000\000\000\000"},
 	{283, "import_from", 0, 8, states_27,
-	 "\000\000\000\000\000\000\000\000\000\010\000\000\000\000\000\000\000\000\000\000\000"},
+	 "\000\000\000\000\000\000\000\000\200\000\000\000\000\000\000\000\000\000\000\000\000"},
 	{284, "import_as_name", 0, 4, states_28,
 	 "\000\000\040\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
 	{285, "dotted_as_name", 0, 4, states_29,
@@ -1821,7 +1812,7 @@ static dfa dfas[81] = {
 	{299, "except_clause", 0, 5, states_43,
 	 "\000\000\000\000\000\000\000\000\000\000\000\000\100\000\000\000\000\000\000\000\000"},
 	{300, "suite", 0, 5, states_44,
-	 "\004\040\040\200\000\000\000\050\170\052\034\000\000\040\004\000\200\041\224\017\100"},
+	 "\004\040\040\200\000\000\000\050\370\044\034\000\000\040\004\000\200\041\224\017\100"},
 	{301, "test", 0, 6, states_45,
 	 "\000\040\040\200\000\000\000\000\000\040\000\000\000\040\004\000\200\041\224\017\000"},
 	{302, "test_nocond", 0, 2, states_46,
@@ -1967,11 +1958,11 @@ static label labels[167] = {
 	{1, "continue"},
 	{1, "return"},
 	{1, "raise"},
+	{1, "from"},
 	{282, 0},
 	{283, 0},
 	{1, "import"},
 	{287, 0},
-	{1, "from"},
 	{23, 0},
 	{52, 0},
 	{286, 0},
diff --git a/Python/import.c b/Python/import.c
index 2ef6aec..33cafd0 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -74,6 +74,7 @@ extern time_t PyOS_GetLastModificationTime(char *, FILE *);
 		      3040 (added signature annotations)
 		      3050 (print becomes a function)
 		      3060 (PEP 3115 metaclass syntax)
+          3070 (PEP 3109 raise changes)
 .
 */
 #define MAGIC (3060 | ((long)'\r'<<16) | ((long)'\n'<<24))
diff --git a/Python/symtable.c b/Python/symtable.c
index 59eef02..83e571e 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1101,13 +1101,11 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
 			VISIT_SEQ(st, stmt, s->v.If.orelse);
 		break;
         case Raise_kind:
-		if (s->v.Raise.type) {
-			VISIT(st, expr, s->v.Raise.type);
-			if (s->v.Raise.inst) {
-				VISIT(st, expr, s->v.Raise.inst);
-				if (s->v.Raise.tback)
-					VISIT(st, expr, s->v.Raise.tback);
-			}
+		if (s->v.Raise.exc) {
+			VISIT(st, expr, s->v.Raise.exc);
+            if (s->v.Raise.cause) {
+                VISIT(st, expr, s->v.Raise.cause);
+            }
 		}
 		break;
         case TryExcept_kind: