FIX: C2166 Incorrect Type Deduction for Template Parameter

• Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

The compiler deduces incorrect type for a template parameter T, associated with a template function that takes a const reference of type T, causing the compiler error C2166 as follows:

l-value specifies const object

RESOLUTION

Do not use a literal when calling the template function. Instead, declare a variable, and pass the variable as an argument to the template function.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been corrected in Visual Studio 97 Service Pack 1.

For additional information about the Visual Studio 97 Service Pack 1, please see the following article in the Microsoft Knowledge Base:

Q170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

The following sample demonstrates the problem and a workaround.

Sample Code

   /*
   * Compiler Options: None
   */ 

   #define BUG
   //Workaround: comment the line above
   //Uncomment the following line
   //#define WORKAROUND

   template<class T> void Test(const T& x)
   {
      T y = x;
      if(y < 0)
         y = -y;
   }

   int main()
   {
   #ifdef BUG
      Test(3) ;
   #endif

   #ifdef WORKAROUND
      int n = 3 ;
      Test(n) ;
   #endif

      return 0 ;
   } 

Additional query words:

Keywords : kbcode kberrmsg kbtool kbCompiler kbCPPonly kbLangCPP kbVC kbVC500bug kbVS97sp1fix
Version : 5.0
Platform : NT WINDOWS
Issue type : kbbug