BUG: C4786 or C1067 Caused by Long Identifier and /Zi (122539)

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions 2.0
Microsoft Visual C++, 32-bit Editions 2.1
Microsoft Visual C++, 32-bit Editions 4.0
Microsoft Visual C++, 32-bit Editions 4.1
Microsoft Visual C++, 32-bit Enterprise Edition 4.2
Microsoft Visual C++, 32-bit Enterprise Edition 5.0
Microsoft Visual C++, 32-bit Enterprise Edition 6.0
Microsoft Visual C++, 32-bit Professional Edition 4.2
Microsoft Visual C++, 32-bit Professional Edition 5.0
Microsoft Visual C++, 32-bit Professional Edition 6.0
Microsoft Visual C++, 32-bit Learning Edition 6.0

This article was previously published under Q122539

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 that this is a bug in the Microsoft products that are 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();
}

Modification Type:	Minor	Last Reviewed:	7/5/2005
Keywords:	kbBug kbCompiler kbCPPonly KB122539