1025871 - Incorrect JavaScript execution when developer tools are open

Status: RESOLVED DUPLICATE of bug 998908

(Core :: JavaScript Engine, defect)

Description

[Artem Malyshev]

Attachment: reproduce.html

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.114 Safari/537.36

Steps to reproduce:

1. Open the developer tools.
2. Switch to the debugger tab.
3. Navigate to a page containing:
<script type="text/javascript">
(function(){
 eval('var a=1; var b=(function(){ alert(typeof a) })()')
})();
</script>


Actual results:

Pop-up saying 'undefined'.


Expected results:

Pop-up saying 'number', since 'a' has type 'number'. This is what happens when developer tools are not open.

Comment 1

[Artem Malyshev]

Attachment: screenshot - no devtools open, JavaScript works as expected

Comment 2

[Artem Malyshev]

Attachment: screenshot - with devtools open, JavaScript does not work as expected

Comment 3

[Artem Malyshev]

Actual user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:30.0) Gecko/20100101 Firefox/30.0

Comment 4

[:Gijs (he/him)]

This wfm on Firefox 31, but breaks on 30. Jan, do you know whether there was just a fix which didn't get uplifted to 30 or something?

Comment 5

[Jan de Mooij [:jandem]]

No idea.. This script should just run in the interpreter FWIW.

Maybe shu or jimb knows?

Comment 6

[Jan de Mooij [:jandem]]

Shu, this looks a lot like bug 998908, can you confirm?

This test also has an inner function inside an eval, and fails in 30, works in 31.

Comment 7

[Alice0775 White]

Progression window(m-i)
Bad:
https://hg.mozilla.org/integration/mozilla-inbound/rev/1fe69cad9713
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0 ID:20140429215012

Fixed:
https://hg.mozilla.org/integration/mozilla-inbound/rev/10e37b92e195
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0 ID:20140429215811

Progression pushlog:
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=1fe69cad9713&tochange=10e37b92e195

Comment 8

[Jan de Mooij [:jandem]]

Thanks again Alice, much appreciated. And Artem, thank you for reporting this.

(In reply to Alice0775 White from comment #7)
> Fixed:
> https://hg.mozilla.org/integration/mozilla-inbound/rev/10e37b92e195
> Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0
> ID:20140429215811

This means comment 6 is correct, this is a duplicate of bug 998908 and will be fixed in the next Firefox version (31).