648634 - Elements of arguments become undefined if reassigned and passed to apply()

Status: RESOLVED DUPLICATE of bug 647425

(Core :: JavaScript Engine, defect)

Description

[Claudio Procida]

User-Agent:       Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_6) AppleWebKit/534.24 (KHTML, like Gecko) Chrome/11.0.696.16 Safari/534.24
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0

We encountered this bug when testing our AJAX application under FF4.0
The problem occurs when:
- a first function invokes an asynchronous operation (e.g. a setTimeout or an XHR operation) hitching its arguments
- a second function, invoked as callback by the async operation, manipulates the arguments object received as actual parameter, and calls a third function
- a third function invokes a final fourth function calling apply() on it and passing the args

Please refer to the attached testcase to reproduce the problem.
The problem does not occur in FF3.6

Reproducible: Always

Steps to Reproduce:
1. Run the attached proof.html into FF4.0
2. Verify an exception is thrown because the argument is undefined
Actual Results:  
Arguments passed to fn.apply(obj, args) that have been reassigned appear as undefined in the called function fn

Expected Results:  
All of the arguments passed to fn.apply(obj, args) should be defined in the called function fn

Comment 1

[Claudio Procida]

Attachment: Testcase for bug 648634

This HTML file contains the set of functions required to reproduce the bug in FF4.0

Comment 2

[Sean Stangl [:sstangl]]

Does not reproduce with latest nightly or with latest TM shell, lin64.

Comment 3

[Sean Stangl [:sstangl]]

Attachment: Testcase with setTimeout() called.

*coughs* Reproduces with setTimeout() not commented out.

Comment 4

[Sean Stangl [:sstangl]]

Attachment: Shell testcase, reproduces.

Comment 5

[Sean Stangl [:sstangl]]

Courtesy of Waldo.