398889 - XPCOMUtils.generateQI throws confusing error when interface doesn't exist

Status: VERIFIED DUPLICATE of bug 477735

(Core :: XPConnect, defect)

Description

[Jason Barnabe (np)]

Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a9pre) Gecko/2007092900 Minefield/3.0a9pre

The code

XPCOMUtils.generateQI([Components.interfaces.thisDoesntExist, Components.interfaces.nsISupports])

throws

JS Component Loader: ERROR file:///home/jason/firefox/dist/bin/modules/XPCOMUtils.jsm:114
                     TypeError: i has no properties

which is fairly confusing. It should throw an error that says the interface doesn't exist.

Comment 1

[Karsten Düsterloh]

Attachment: safeguard object member access

If the interface doesn't exist or if you just pass null, i.name will throw on its own accord. Safeguarding this, we'll pass null down to the QI and correctly get NS_ERROR_NO_INTERFACE.

Comment 2

[:Gavin Sharp [email: [e-mail]]]

Already fixed in bug 477735. Were you looking at the 1.9.1 branch?

Comment 3

[Karsten Düsterloh]

Basically I think my patch is more elegant than Vlad's... ;-)
But it's good to see it's fixed.

Comment 4

[:Gavin Sharp [email: [e-mail]]]

The one he actually landed is functionally equivalent:
http://hg.mozilla.org/mozilla-central/rev/0ce096d6b9df

Comment 5

[Serge Gautherie (:sgautherie)]

V.Duplicate