Q122539: BUG: C4786 or C1067 Caused by Long Identifier and /Zi

Article: Q122539
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbCPPonly kbVC kbVC500bug
Last Modified: 11-FEB-2002

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The information in this article applies to:

- The C/C++ Compiler (CL.EXE), included with:
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

Using Visual C++ version 4.x and later to compile a C++ program with the /Zi
option generates the following warning:

  warning C4786: 'identifier' : identifier was truncated to '255' characters in
  the debug information

Or, using Visual C++ version 2.x to compile a C++ program with the /Zi option
generates the following error:

  fatal error C1067: compiler limit : debug information module size exceeded.
  Error executing cl.exe.

CAUSE
=====

The warning and error are caused by symbols with decorated names that exceed 255
and 247 characters, respectively.

RESOLUTION
==========

The best solution is to shorten the length of the identifier or compile for
Release mode. If the identifier is a function call, reducing the number of
parameters will help reduce the length.

To work around the fatal error C1067, users of Visual C++ version 2.x can also
generate debugging information with the /Z7 (C7 Compatible) switch instead of
the /Zi (Program Database) switch. With Visual C++ versions 2.x and later, using
/Z7 generates the C4786 warning as listed above. This warning can be ignored
although the identifier may not be accessible or viewable in the debugger.

STATUS
======

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

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

The following sample code can be used to demonstrate the problem.

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

  /* Compile options needed: /Zi
  */ 

  #include <conio.h>
  // The next three lines should be on one continous line
   class CAboutClassaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
         aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbb
         bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
  {
  public:
  // The next three lines should be on one continous line
         CAboutClassaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
         aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbb
         bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb() {}

  // The next three lines should be on one continous line
        ~CAboutClassaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
         aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbb
         bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb(){}
   };
  void main(void)
  {
  // The next three lines should be on one continous line
   CAboutClassaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
         aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbb
         bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb test1;
         getch();
  }

Additional query words: kbVC400bug 9.00 10.00 10.10 10.20 buglist2.00

======================================================================
Keywords          : kbCompiler kbCPPonly kbVC kbVC500bug 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :2.0,2.1,4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug

=============================================================================

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