Strange behavior

[John C]

yvad Wrote:

> QueryInterface of type HRESULTWindows (GUID * riidriid, out void* ppvObject ppvObject) overrides but is not covariant with QueryInterface of type HRESULT(GUID * riidriid, void* ppvObject ppvObject) 

I'm surprised that's the error you get. Copying your code (and filling in the blanks) I instead get an error about an undefined symbol. You need to mark QueryInterface in AbstractUnknown as abstract.