697300 - Cascaded event listeners don't throw exceptions

Status: RESOLVED DUPLICATE of bug 503244

(Core :: DOM: Events, defect)

Description

[Sonny Piers [:sonny]]

Attachment: testcase.xhtml

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0a1) Gecko/20111025 Firefox/10.0a1
Build ID: 20111025031041

Steps to reproduce:

Neither exceptions or user defined exceptions are thrown on the error console when the execution context in a DOM3 CustomEvent listener.
See my attachment testcase.xhml

Comment 1

[Paul Rouget [:paul]]

This page http://jsfiddle.net/2Kvpy/6/ throws an exception.
It is not shown in the Web Console.

Comment 2

[Boris Zbarsky [:bzbarsky]]

This is not special to custom events, is it?

Comment 3

[Paul Rouget [:paul]]

I think it is (same code but with a click event works as expected).

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

(In reply to Paul Rouget [:paul] from comment #3)
> I think it is (same code but with a click event works as expected).

If I change your testcase to create "Event" and call initEvent, the behavior is the same as
with creating CustomEvent. And I see same behavior with MouseEvent.click too.

It is not clear to me this has anything to do with CustomEvent.

Could someone write a testcase which shows that this is specific to CustomEvents.

(I believe this is dup of a bug where exceptions thrown from addEventListener-added listener
aren't shown in the error console, or something like that. That bug is, IIRC, somewhere in
XPConnect level)

Comment 5

[Sonny Piers [:sonny]]

Attachment: testcase

Comment 6

[Sonny Piers [:sonny]]

(In reply to Olli Pettay [:smaug] from comment #4)
> It is not clear to me this has anything to do with CustomEvent.
You're right, not related with CustomEvent.

It looks related to cascaded event listeners, see the new testcase.

Comment 7

[Josh Matthews [:jdm]]

Stepping through this in gdb, it looks like the same problem as bug 503244. XPCWrappedJSClass::CheckForException calls the error reporter, which sees JS on the stack and doesn't report, then clears the pending exception.

Comment 8

[Josh Matthews [:jdm]]

Given that a patch for bug 503244 also fixes this bug, I'm calling this a duplicate. This is a helpful testcase though; thanks.