Darin Fisher wrote:
> I have the following QI map:
>
> NS_INTERFACE_MAP_BEGIN(nsFtpControlConnection)
> NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
> NS_INTERFACE_MAP_ENTRY(nsIStreamProvider)
> NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsIStreamObserver, nsIStreamListener)
> NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIStreamListener)
> NS_INTERFACE_MAP_END_THREADSAFE
>
> with
>
> class nsFtpControlConnection : public nsIStreamListener, public
> nsIStreamProvider { ... }
>
> The following code works:
>
> nsFtpControlConnection *fcc = ...
> nsCOMPtr<nsISupports> sup1 = (nsIStreamListener*) fcc;
> nsCOMPtr<nsISupports> sup2 = (nsIStreamProvider*) fcc;
> nsCOMPtr<nsIStreamObserver> obs1 = (nsIStreamListener*) fcc;
>
> However, this line does not:
>
> nsCOMPtr<nsIStreamObserver> obs2 = (nsIStreamProvider*) fcc;
>
> It hits the nsCOMPtr assertion:
>
> ###!!! ASSERTION: QueryInterface needed: 'query_result.get() ==
> mRawPtr', file ../../../../dist/include/nsCOMPtr.h, line 499
>
> I am confused why this is happening? I'm hoping that someone could
> enlighten me... thanks!
> Darin
>
I should add:
interface nsIStreamListener : nsIStreamObserver { ... }
interface nsIStreamProvider : nsIStreamObserver { ... }
interface nsIStreamObserver : nsISupports { ... }
