647119 - eval('(this)') == true, while (this) without eval function is an object.

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[windspirit]

User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:2.0) Gecko/20110322 Firefox/4.0
Build Identifier: Mozilla/5.0 (X11; Linux x86_64; rv:2.0) Gecko/20110322 Firefox/4.0

it is pretty clear.
alert((this));
alert(eval('(this)'));
should give same result.
but second one will say "true". 

 

Reproducible: Always

Steps to Reproduce:
1. alert(eval('(this)'));

Comment 1

[Masatoshi Kimura [:emk]]

Confirming on Windows XP. Other browsers (at least IE8 and Chrome) works as expected.
Not limited to Developer Tools, x86_64, and Linux.

Comment 2

[Alice0775 White]

Regression window(TM nightly)
Works:
http://hg.mozilla.org/tracemonkey/rev/fa851447f195
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100824 Minefield/4.0b5pre ID:20100824043743
Fails:
http://hg.mozilla.org/tracemonkey/rev/7680aecfb0c6
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100826 Minefield/4.0b5pre ID:20100826044040
Pushlog:
http://hg.mozilla.org/tracemonkey/pushloghtml?fromchange=fa851447f195&tochange=7680aecfb0c6

In local build on ubuntu(tm repository)
build from 5685f8de41fa : fails
build from fa851447f195 : works
Treiggered by:
5685f8de41fa	Nicholas Nethercote — Bug 578216 - Make eval(json-like string) fast. r=sayrer

Comment 3

[Jan de Mooij [:jandem]]

So the underlying problem here is that JSON.parse("this") returns true...

Comment 4

[Jeff Walden [:Waldo]]

Not surprisingly, the JSON parser rewrite fixes this.

Comment 5

[Jeff Walden [:Waldo]]

Fixed by the parser rewrite in bug 589664.