679719 - Arguments object bugs within closure in Firefox5 (regression of bug 647425)

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Claudio Procida]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:5.0.1) Gecko/20100101 Firefox/5.0.1
Build ID: 20110707182747

Steps to reproduce:

I was able to reproduce bug 6472425 in Firefox 5.0. It looks like regression from FF4.0.1.

User-Agent:  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:5.0.1) Gecko/20100101 Firefox/5.0.1"
Build Identifier: "20110707182747"

(function() {
		var args = arguments;
		function n() {
				args[0] = "caimc";
				alert.apply(null, args);
		}
		setTimeout(n,0);
})("cmc");

IN FF5.0.1 it alert undefined - should be ‘caimc’！

Reproducible: Always

Steps to Reproduce:
1.execute the code at details

Actual Results:  
undefined

Expected Results:  
caimc

Comment 2

[Boris Zbarsky [:bzbarsky]]

Is this really a duplicate of an ancient bug?  I sort of doubt it.

In particular, the attached testcase works for me in Firefox 3.6, fails in Fx4 and Fx5, and passes again in Fx6....  So it does look like something regressed and then was fixed.  Can we add a testcase for it?

Comment 3

[David Mandelin [:dmandelin]]

Can someone get us the full regression history on this test case?