From 9e809c98e504fbafb39dd83500c5fcdaf7783ddf Mon Sep 17 00:00:00 2001
From: Brian Hackett <bhackett1024@gmail.com>
Date: Thu, 11 Apr 2013 16:19:10 -0600
Subject: [PATCH] Bug 855088 - Watch for 'arguments' variables declared within
 'with' blocks, r=luke.

---
 js/src/frontend/Parser.cpp               | 16 ++++++++++++++--
 js/src/jit-test/tests/basic/bug855088.js |  5 +++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 js/src/jit-test/tests/basic/bug855088.js

diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 13077a4e06e..355f15644b6 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -2493,8 +2493,20 @@ Parser<FullParseHandler>::bindVarOrConst(JSContext *cx, BindData<FullParseHandle
 
     if (stmt && stmt->type == STMT_WITH) {
         pn->pn_dflags |= PND_DEOPTIMIZED;
-        if (pc->sc->isFunctionBox())
-            pc->sc->asFunctionBox()->setMightAliasLocals();
+        if (pc->sc->isFunctionBox()) {
+            FunctionBox *funbox = pc->sc->asFunctionBox();
+            funbox->setMightAliasLocals();
+
+            /*
+             * This definition isn't being added to the parse context's
+             * declarations, so make sure to indicate the need to deoptimize
+             * the script's arguments object.
+             */
+            if (name == cx->names().arguments) {
+                funbox->setArgumentsHasLocalBinding();
+                funbox->setDefinitelyNeedsArgsObj();
+            }
+        }
         return true;
     }
 
diff --git a/js/src/jit-test/tests/basic/bug855088.js b/js/src/jit-test/tests/basic/bug855088.js
new file mode 100644
index 00000000000..9d1145616de
--- /dev/null
+++ b/js/src/jit-test/tests/basic/bug855088.js
@@ -0,0 +1,5 @@
+
+(function (y) {
+    arguments.y = 2;
+    with (0) var arguments=5;    
+})(1);