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Q122789: FIX: Error C2579 When Using Function Templates

Article: Q122789
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,4.0,4.1,4.2
Operating System(s): 
Keyword(s): kbtool kbCompiler kbCPPonly kbVC kbVC500fix
Last Modified: 15-FEB-2002

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft C/C++ Compiler (CL.EXE), included with:
   - Microsoft Visual C++, 32-bit Editions, versions 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'

Visual C++ version 2.x may generate the following errors:

  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;
     }

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

======================================================================
Keywords          : kbtool kbCompiler kbCPPonly kbVC kbVC500fix 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :2.0,2.1,4.0,4.1,4.2
Issue type        : kbbug
Solution Type     : kbfix

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

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