DOCUMENT:Q131147  29-JUL-2001  [visualc]
TITLE   :FIX: CXX0033 Error in OMF Type from Forward Class Declaration
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:
OPER/SYS:
KEYWORDS:kbCompiler kbDebug kbidekbbuglist kbfixlist

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - The C/C++ Compiler (CL.EXE), included with:
    - Microsoft Visual C++, versions 1.0, 1.5, 1.51, 1.52 
    - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, versions 1.0, 2.0, 2.1 
-------------------------------------------------------------------------------

SYMPTOMS
========

In the Visual C++ debugger, if you debug an application built using precompiled
header (PCH) options, the debugger's expression evaluator may generate errors
when viewing classes that were declared but not defined in the precompiled
header file.

One of the following errors may be generated depending on the Visual C++
version:

   CXX0017 Error: symbol "xxxx" cannot be found

   CXX0030 Error: expression cannot be evaluated

   CXX0033 Error: error in OMF type information

   CV1255 Error: no data members

NOTE: The first error message is very generic, and can occur for several
different reasons including this one.

CAUSE
=====

When the compiler writes out type information into the program database (.PDB)
file, incomplete type information is written for the forward class declaration
when the full definition has not yet been compiled.

When the module containing the full class definition is compiled, the complete
type information is not replacing the incomplete type information in the .PDB
file.

RESOLUTION
==========

Here are three possible workarounds:

 - Turn off PCH usage. This avoids the problem altogether.

-or-

 - Include the full definition of the class in .PCH file. This causes the
   complete type information to be written to the .PDB file.

-or-

 - Compile using C7 Compatible Debug Info switch (/Z7). This will not use a .PDB
   file to store type information. You may also need to use the /Yd option to
   include PCH debug information in all object modules.


STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was fixed in Microsoft Visual C++,
32-bit Edition, version 4.0.

MORE INFORMATION
================

The following small sample application reproduces the problem. In the Visual C++
integrated debugger, it is not possible to expand "A" in the locals window,
watch window, or with a quickwatch.

Sample Code to Demonstrate Problem
----------------------------------

   /* PCH.H
   */ 
   class FwdNonPCHClass;

   class PCHClass
   {
    public:
      int i;
      long l;
      class FwdClass * FwdNonPCHClassPtr;
   };

   /*
      STDPCH.CPP
      Win32 Compile options needed: /Yc"pch.h" /Od /Zi /c
      Win16 Compile options needed: /Yc"pch.h" /Od /Zi /Mq /c

   */ 
   #include "pch.h"

   /*
      TEST.CPP
      Win32 Compile options needed: /Yu"pch.h" /Od /Zi test.cpp stdpch.obj
      Win16 Compile options needed: /Yu"pch.h" /Od /Zi /Mq test.cpp stdpch.obj

   */ 
   #include "pch.h"

   class FwdNonPCHClass
   {
    public:
    int i;
    long l;
   };

   void main(void)
   {
   FwdNonPCHClass A;
   PCHClass B;

   A.i = 1;
   A.l = 17L;

   B.i = 54;
   B.l = 17L;
   }

Additional query words: 1.00 1.50 1.51 1.52 1.52a 2.00 2.10 8.0 8.00 8.0c 8.00c 9.0 9.00 9.1 9.10

======================================================================
Keywords          : kbCompiler kbDebug kbide kbbuglist kbfixlist
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:
Issue type        : kbbug
Solution Type     : kbfix

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