303720 - XPConnect sometimes stomps on a pending JS exception

Status: RESOLVED INCOMPLETE

(Core :: XPConnect, defect)

Description

[Brendan Eich [:brendan]]

I found this while debugging bug 303163.  In that case, a syntax error exception
thrown by the compiler was pending, but nsEventListenerManager code called from
nsDOMClassInfo.cpp's nsEventReceiverSH::RegisterCompileHandler took that JS
error and turned it into NS_ERROR_FAILURE, which XPConnect's
XPC_WN_Helper_NewResolve then wrapped into a new exception via Throw(rv, cx). 
That stomped the pending JS error.

/be

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Patch that really ought to work but doesn't

I'd have thought that something like this would work, but this makes no errors
at all appear.	If I keep returning NS_ERROR_FAILURE, then I do get those
errors, but the first syntax error is still eaten by something...