Compiler Error C3705

'function' : cannot find eventing interface

You must define an event interface to use COM events. Note that the #include lines of the ATL header files shown in the sample below are required for using COM events. To fix this error, uncomment the definition of the IEvents interface in the sample code.

The following sample generates C3705:

// C3705.cpp
// compile with: /c
#define _ATL_ATTRIBUTES 1
#include <atlbase.h>
#include <atlcom.h>
#include <atlctl.h>

[module(dll, name="idid", uuid="12341234-1234-1234-1234-123412341234")];

// Uncomment the following 4 lines to resolve.
// [object, uuid("00000000-0000-0000-0000-000000000003")]
// __interface IEvents : IUnknown {
//    HRESULT event1([in] int i);
// };

[dual, uuid("00000000-0000-0000-0000-000000000001")]
__interface IBase {
   HRESULT fireEvents();
};

[coclass, event_source(com), uuid("00000000-0000-0000-0000-000000000002")]
class CEventSrc : public IBase {
public:
   __event __interface IEvents;   // C3705 uncomment IEvents to resolve
   HRESULT fireEvents() {
      HRESULT hr = IEvents_event1(123);
      return hr;
   }
};