FIX: Compiler Incorrectly Causes Default Constructor Reference (172980)

The information in this article applies to:

Microsoft Visual C++, 32-bit Enterprise Edition 5.0
Microsoft Visual C++, 32-bit Professional Edition 5.0

This article was previously published under Q172980

SYMPTOMS

When instantiating a class template with a member function that has a default parameter, error C2512 may be generated.

CAUSE

This behavior can occur when the default parameter is an explicitly-created temporary of the parameterized type of the template. The sample code below demonstrates this.

RESOLUTION

Do not use an explicitly-generated temporary as a default argument.

-or-

Ensure that the template argument has a default constructor available.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3.

For more information, please see the following article in the Microsoft Knowledge Base:

170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Sample

   // compile options : /c
   template<typename T>
   class C
   {
   public:
       void fn(const T & t = T());
   };
   class X
   {
   public:
       X(int);
       ~X();
   };
   C<X> l;

Modification Type:	Minor	Last Reviewed:	7/5/2005
Keywords:	kbBug kbCompiler kbCPPonly kbfix kbVS97sp2fix KB172980