The spec says: "A COM interface is defined as one that derives from the interface core.stdc.windows.com.IUnknown." https://dlang.org/spec/interface.html#com-interfaces However an interface derived from another interface named "IUnknown", whatever its content and fully qualified name, will also be considered COM, with the semantics restrictions. This is very desirable since it allow to use COM interfaces with sayn @nogc signatures, or COM without Windows. So the spec is wrong about this, core.stdc.windows.com.IUnknown is not needed, but the name "IUnknown" is.
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