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

• Microsoft C/C++ Compiler (CL.EXE) included with: - Microsoft Visual C++, 32-bit Edition, versions 2.0, 2.1, 4.0, 4.1,

       4.2, 5.0
  

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

   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 workaround 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 products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

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();
   }