BUG: Enum in Function Template Causes C2065 Compiler Error

ID: Q125495

The information in this article applies to:

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

SYMPTOMS

When an enum type is used as a return type of a function template, the compiler generates the following error as the function template is instantiated:

Error C2065 : 'FunctionName' : undeclared identifier
Error C2064 : term does not evaluate to a function

This error happens only when the function template takes arguments that involve a user-defined class template. For more information, please see the "Sample Code" section in this article.

RESOLUTION

To work around the problem, use a typedef to define the enum type, and use it as the return type for the function template.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft 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 sample code below can be used to demonstrate both the problem and its solution.

Sample Code


/* Compile options needed: none
   Use /DFIX to work around the problem
*/ 

template <class Type>
class TestClass
{
  Type t;
};

enum EnumType { E1, E2, E3 };

#ifndef FIX        // Used to reproduce the problem

   template <class Type>
   EnumType EnumReturnDoesntWork( const TestClass<Type> &a )
   {
     return E1;
   }

#else              // Used to work around the problem

   typedef EnumType MyType;

   template <class Type>
   MyType EnumReturnDoesntWork( const TestClass<Type> &a )
   {
     return E1;
   }

#endif

void main(void)
{
   TestClass<int> a;

   EnumReturnDoesntWork( a );   // C2065
}

Additional query words: 2.00 2.10 9.00 9.10 noupdate

Keywords : kbCompiler kbCPPonly kbVC
Version : :2.0,2.1
Platform : NT WINDOWS
Issue type :