BUG: Debugger Cannot Watch Function Returning struct or union

ID: Q177937

The information in this article applies to:

SYMPTOMS

Adding a function call in the Developer Studio debugger Watch window may result in the following message if the function returns a struct or union with a field width greater than 4 bytes:

Error: cannot display value


RESOLUTION

There is no workaround for this problem.


STATUS

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


MORE INFORMATION

The following procedure reproduces this problem:

  1. Create a new console application project and add the following file to the project: 
    
      /* File: TEST.CPP */ 

       struct _XX
           {
           char   m1;
           char   m2;
           char   m3;
           char   m4;
           } XX;

       struct _XX fun()
       {
           return XX;
       }

       int main()
       {
           fun();
           return 0;
       }


  2. Build the project.


  3. Click Build|Start Debug|Step Into on the Developer Studio menu.


  4. Goto the Watch window by selecting View|Debug Windows|Watch.


  5. Add the following watch expression in the "Name" column: fun()


Results: You will see the message "Error: cannot display value" in the "Value" column.

Additional query words: 


Keywords          : kbDebug kbide kbVC500bug kbVC600bug 
Version           : winnt:5.0,5.0sp1,5.0sp2,6.0
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: May 17, 1999