Issue #9128: Fix validation of class decorators in parser module.

Lib/test/test_parser.py

@@ -149,6 +149,13 @@ class RoundtripLegalSyntaxTestCase(unittest.TestCase):
     def test_class_defs(self):
         self.check_suite("class foo():pass")
         self.check_suite("class foo(object):pass")
+        self.check_suite("@class_decorator\n"
+                         "class foo():pass")
+        self.check_suite("@class_decorator(arg)\n"
+                         "class foo():pass")
+        self.check_suite("@decorator1\n"
+                         "@decorator2\n"
+                         "class foo():pass")
 
     def test_import_from_statement(self):
         self.check_suite("from sys.path import *")

Misc/NEWS

@@ -468,6 +468,8 @@ C-API
 Library
 -------
 
+- Issue #9128: Fix validation of class decorators in parser module.
+
 - Issue #9094: python -m pickletools will now disassemble pickle files
   listed in the command line arguments.  See output of python -m
   pickletools -h for more details.

Modules/parsermodule.c

@@ -2512,10 +2512,11 @@ validate_decorated(node *tree)
     int nch = NCH(tree);
     int ok = (validate_ntype(tree, decorated)
               && (nch == 2)
-            && validate_decorators(RCHILD(tree, -2))
-            && (validate_funcdef(RCHILD(tree, -1))
-                || validate_class(RCHILD(tree, -1)))
-            );
+              && validate_decorators(RCHILD(tree, -2)));
+    if (TYPE(RCHILD(tree, -1)) == funcdef)
+        ok = ok && validate_funcdef(RCHILD(tree, -1));
+    else
+        ok = ok && validate_class(RCHILD(tree, -1));
     return ok;
 }