FIX: Error C2579 When Using Function Templates

• The Microsoft C/C++ Compiler (CL.EXE) included with: - Microsoft Visual C++, 32-bit Edition, version 2.0, 2.1, 4.0, 4.1, 4.2

SYMPTOMS

When compiling function templates that contain a literal character, the compiler may complain about 'ambiguous' parameter lists. Visual C++ version 4.0 may generate the following error:

   error C2579: 'identifier1' : parameter list not
      sufficiently different from 'identifier2'

   error C2579: 'identifier1' : parameter list not
      sufficiently different from 'identifier2'
   fatal error C1903: unable to recover from previous
      error(s); stopping compilation

RESOLUTION

Explicitly type cast the literal character with "(char)" to eliminate this error. For example, in the sample code provided below, cast the literal character 'c' to (char)'c' to work around the problem.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ version 5.0.

MORE INFORMATION

You can use the following sample code to demonstrate the problem. Both functions (func(c) and func('c')) are necessary to reproduce the problem.

Sample Code to Reproduce Problem

   /* Compile options needed: none
   */

   template <class T>
   int func(T)
   {
      static int x = 0;
      return x;
   }

   main()
   {
      char c;

      func(c);
      func('c');
      return 0;
   }