From 9dfe6a8862f6125cc4b22bd8779126ac29839bab Mon Sep 17 00:00:00 2001
From: Benjamin Peterson <benjamin@python.org>
Date: Mon, 24 Nov 2008 04:09:03 +0000
Subject: [PATCH] #4396 make the parser module correctly validate the with
 syntax

---
 Lib/test/test_parser.py |  4 ++++
 Misc/NEWS               |  5 +++++
 Modules/parsermodule.c  | 38 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_parser.py b/Lib/test/test_parser.py
index 94b6113a0c3..1069606cffb 100644
--- a/Lib/test/test_parser.py
+++ b/Lib/test/test_parser.py
@@ -196,6 +196,10 @@ class RoundtripLegalSyntaxTestCase(unittest.TestCase):
     def test_assert(self):
         self.check_suite("assert alo < ahi and blo < bhi\n")
 
+    def test_with(self):
+        self.check_suite("with open('x'): pass\n")
+        self.check_suite("with open('x') as f: pass\n")
+
     def test_position(self):
         # An absolutely minimal test of position information.  Better
         # tests would be a big project.
diff --git a/Misc/NEWS b/Misc/NEWS
index b7e80a9d2df..8d8b6c5cc04 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -106,6 +106,11 @@ C-API
 - Issue #4122: On Windows, fix a compilation error when using the
   Py_UNICODE_ISSPACE macro in an extension module.
 
+Extension Modules
+-----------------
+
+- Issue #4396: The parser module now correctly validates the with statement.
+
 
 What's New in Python 2.6 final
 ==============================
diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index bea78c2ce12..95fcdcdd6d9 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -1559,7 +1559,7 @@ validate_small_stmt(node *tree)
 
 
 /*  compound_stmt:
- *      if_stmt | while_stmt | for_stmt | try_stmt | funcdef | classdef | decorated
+ *      if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated
  */
 static int
 validate_compound_stmt(node *tree)
@@ -1577,6 +1577,7 @@ validate_compound_stmt(node *tree)
           || (ntype == while_stmt)
           || (ntype == for_stmt)
           || (ntype == try_stmt)
+          || (ntype == with_stmt)
           || (ntype == funcdef)
           || (ntype == classdef)
           || (ntype == decorated))
@@ -2617,6 +2618,38 @@ validate_decorators(node *tree)
     return ok;
 }
 
+/*  with_var
+with_var: 'as' expr
+ */
+static int
+validate_with_var(node *tree)
+{
+    int nch = NCH(tree);
+    int ok = (validate_ntype(tree, with_var)
+        && (nch == 2)
+        && validate_name(CHILD(tree, 0), "as")
+        && validate_expr(CHILD(tree, 1)));
+   return ok;
+}
+
+/*  with_stmt
+ *           0      1       2       -2   -1
+with_stmt: 'with' test [ with_var ] ':' suite
+ */
+static int
+validate_with_stmt(node *tree)
+{
+    int nch = NCH(tree);
+    int ok = (validate_ntype(tree, with_stmt)
+        && ((nch == 4) || (nch == 5))
+        && validate_name(CHILD(tree, 0), "with")
+        && validate_test(CHILD(tree, 1))
+        && (nch == 4 || validate_with_var(CHILD(tree, 2))) 
+        && validate_colon(RCHILD(tree, -2))
+        && validate_suite(RCHILD(tree, -1)));
+   return ok;
+}
+
 /*  funcdef:
  *      
  *     -5   -4         -3  -2    -1
@@ -2993,6 +3026,9 @@ validate_node(node *tree)
           case funcdef:
             res = validate_funcdef(tree);
             break;
+          case with_stmt:
+            res = validate_with_stmt(tree);
+            break;
           case classdef:
             res = validate_class(tree);
             break;