FIX: Out of Order Definitions in idl May Cause Compiler Errors

• The C/C++ Compiler (CL.EXE), included with:
  • Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

When using the #import directive, errors may be generated due to the order in which definitions appear in the idl file used to generate the type library. The sample below causes error C2504, base class undefined, due to the interfaces being defined globally instead of in the library block.

RESOLUTION

Move the interface definitions into the library block.

- or -

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3.

For more information, please see the following article in the Microsoft Knowledge Base:

Q170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Sample

   // t.cpp
      // Compile options: /c
      #import "t.tlb"

   // t.idl
      // command line: midl t.idl

      // move the definitions of A and B into the
      // library block for one workaround
      [ uuid( 10000000-0000-0000-0000-000000000000 ) ]
      interface A : IUnknown
      {
      };
      [ uuid( 20000000-0000-0000-0000-000000000000 ) ]
      interface B : A
      {
      };
      [ uuid( 30000000-0000-0000-0000-000000000000 ) ]
      library Test
      {
         importlib("stdole2.tlb");

         // uncomment this coclass for another workaround
         // [ hidden, uuid( 40000000-0000-0000-0000-000000000000 ) ]
         //coclass Dummy
         //{
         //   interface A;
         //}

         [ uuid( 50000000-0000-0000-0000-000000000000 ) ]
         coclass C
         {
            interface B;
         }
      } 

Additional query words: midl

Keywords : kbCompiler kbCPPonly kbVC500bug kbVS97sp2fix
Version : WINNT:5.0
Platform : winnt
Issue type : kbbug