Ensure that the length property of bound functions are actual unique

for the individually bound functions.

Our existing code will generate a new function on every call to bind,
but it will use the same shared function. When setting the lenght this
will be set on the shared function, i.e., the length of all bound
functions will be that of the last bound function.
Review URL: http://codereview.chromium.org/7475002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8816 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -2002,6 +2002,24 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionSetLength) {
 }
 
 
+// Creates a local, readonly, property called length with the correct
+// length (when read by the user). This effectively overwrites the
+// interceptor used to normally provide the length.
+RUNTIME_FUNCTION(MaybeObject*, Runtime_BoundFunctionSetLength) {
+  NoHandleAllocation ha;
+  ASSERT(args.length() == 2);
+  CONVERT_CHECKED(JSFunction, fun, args[0]);
+  CONVERT_CHECKED(Smi, length, args[1]);
+  MaybeObject* maybe_name =
+      isolate->heap()->AllocateStringFromAscii(CStrVector("length"));
+  String* name;
+  if (!maybe_name->To(&name)) return maybe_name;
+  PropertyAttributes attr =
+      static_cast<PropertyAttributes>(DONT_DELETE | DONT_ENUM | READ_ONLY);
+  return fun->AddProperty(name, length, attr, kNonStrictMode);
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionSetPrototype) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);

src/runtime.h

@@ -209,6 +209,7 @@ namespace internal {
   /* Reflection */ \
   F(FunctionSetInstanceClassName, 2, 1) \
   F(FunctionSetLength, 2, 1) \
+  F(BoundFunctionSetLength, 2, 1)    \
   F(FunctionSetPrototype, 2, 1) \
   F(FunctionSetReadOnlyPrototype, 1, 1) \
   F(FunctionGetName, 1, 1) \

src/v8natives.js

@@ -1498,9 +1498,9 @@ function FunctionBind(this_arg) { // Length is 1.
 
   // Set the correct length.
   var length = (this.length - argc_bound) > 0 ? this.length - argc_bound : 0;
-  %FunctionSetLength(result, length);
   %FunctionRemovePrototype(result);
   %FunctionSetBound(result);
+  %BoundFunctionSetLength(result, length);
   return result;
 }
 

test/mjsunit/regress/regress-1419.js

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test that using bind several time does not change the length of existing
+// bound functions.
+
+function foo() {
+}
+
+var f1 = function (x) {}.bind(foo);
+var f2 = function () {};
+
+assertEquals(1, f1.length);
+
+// the object we bind to can be any object
+f2.bind(foo);
+
+assertEquals(1, f1.length);
+
+var desc = Object.getOwnPropertyDescriptor(f1, 'length');
+assertEquals(false, desc.writable);
+assertEquals(false, desc.enumerable);
+assertEquals(false, desc.configurable);