288698 - Components.returnCode not propagated back to do_CreateInstance

Status: RESOLVED DUPLICATE of bug 287107

(Core :: XPConnect, defect)

Description

[[e-mail]]

I had an obsolete helperAppDlg.xpt in my components directory so when the
nsIHelperAppLauncherDialog IID got revised recently my depend build did not pick
up the change. This meant that the nsHelperAppDlg.js component was unable to
QueryInterface to the new IID. Despite its QueryInterface implementation setting
Components.returnCode to NS_ERROR_NO_INTERFACE js_Invoke returned JS_TRUE thus
returning NS_OK to the do_CreateInstance call although the result was nsnsull.
[nsDocShell subsequently crashed as it relies on NS_ENSURE_SUCCESS(rv, rv);]

Comment 1

[Boris Zbarsky [:bzbarsky]]

So.. first question is whether the JS should be throwing or just setting
returnCode.  I don't know that this is actually documented anywhere, is it?

Comment 2

[Benjamin Smedberg]

> So.. first question is whether the JS should be throwing or just setting
> returnCode.  I don't know that this is actually documented anywhere, is it?

I sure couldn't find it. Perhaps throwing should show the JS console warning,
while setting Components.returnCode should just throw a COM exception? What
happens if you set .returnCode to a success code?

Comment 3

[David Bradley]

Currently XPConnect ignores the return code if a JS error is not signal. That 
may change in the near future, as there is a bug on that.

Comment 4

[[e-mail]]

Note that
Components.classes['@mozilla.org/helperapplauncherdialog;1']
          .createInstance(Components.interfaces.nsISupportsString)
asserts in xpcjscid.cpp:810 because instance is null but
Components.classes['@mozilla.org/helperapplauncherdialog;1']
          .createInstance(Components.interfaces.nsISupports)
          .QueryInterface(Components.interfaces.nsISupportsString)
throws NS_NOINTERFACE to JS but that's more xpc fu :-/

Comment 5

[Christian :Biesinger (don't email me, ping me on IRC)]

docs are at http://www.mozilla.org/scriptable/components_object.html#_returnCode

>Perhaps throwing should show the JS console warning,
>while setting Components.returnCode should just throw a COM exception? 

That certainly was the intent of these throw -> returnCode changes (bug 243621)

Comment 6

[Brendan Eich [:brendan]]

Isn't this a dup of bug 287107?

Unfortunately, I had to back out my patch to fix that bug because it exposed
places in Firefox and forumzilla that depend on the bug.

/be

Comment 7

[Brendan Eich [:brendan]]

*** This bug has been marked as a duplicate of 287107 ***