From 0e4c930b3ee136350c185eb0c02bb34ec84ea238 Mon Sep 17 00:00:00 2001
From: Stefan Behnel <scoder@users.berlios.de>
Date: Fri, 3 Dec 2010 21:17:30 +0100
Subject: [PATCH] made fields of builtin objects immutable

---
 Cython/Compiler/ExprNodes.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Cython/Compiler/ExprNodes.py b/Cython/Compiler/ExprNodes.py
index f6966165..d721a69e 100755
--- a/Cython/Compiler/ExprNodes.py
+++ b/Cython/Compiler/ExprNodes.py
@@ -3451,7 +3451,9 @@ class AttributeNode(ExprNode):
             if not target:
                 self.is_temp = 1
                 self.result_ctype = py_object_type
-    
+        elif target and self.obj.type.is_builtin_type:
+            error(self.pos, "Assignment to an immutable object field")
+
     def analyse_attribute(self, env, obj_type = None):
         # Look up attribute and set self.type and self.member.
         self.is_py_attr = 0
-- 
2.26.2