Q116170: FIX: C2099 Generated Initializing Struct with Macro

Article: Q116170
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,2.0,4.0,4.1,4.2,5.0,7.0
Operating System(s): 
Keyword(s): kbVC100bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600fix
Last Modified: 14-FEB-2002

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The information in this article applies to:

- Microsoft C/C++ Compiler (CL.EXE), included with:
   - Microsoft C/C++, version 7.0 
   - Microsoft Visual C++, versions 1.0, 1.5, 2.0, 4.0, 4.1, 4.2 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 5.0 
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SYMPTOMS
========

Using a macro to initialize a structure causes the C/C++ compiler to incorrectly
generate the following error message:

  error C2099: initializer is not a constant

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.

This problem was corrected in Microsoft Visual C++ version 6.0.

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

The sample code below can be used to reproduce this problem:

Sample Code
-----------

     /* Compile options needed: none
     */ 

     #include <stddef.h>

     #define ZIP     struct zip_struct
     #define ZOT     struct zot_struct
     #define TABLE   struct table_struct

     ZIP
     {
        ZOT
        {
           int num;
        } m_zot;
     };

     #define MACRO(tok) \ 
        { (offsetof(ZIP, m_zot.tok) - offsetof(ZIP, m_zot)) / sizeof(int) }

     TABLE
     {
        int Offset;
        int ModNum;
     };

     TABLE test[] = { { offsetof(ZIP, m_zot.num) - offsetof(ZIP, m_zot)
                      / sizeof(int) } };
     TABLE test2[] = { { MACRO(num) } };

     void main(void)
     {
     }

Additional query words: kbVC400bug 8.00 8.00c 9.00 10.00 10.10 10.20

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Keywords          : kbVC100bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600fix 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :1.0,1.5,2.0,4.0,4.1,4.2,5.0,7.0
Issue type        : kbbug
Solution Type     : kbfix

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