FIX: C2985 Error When Template Class Has Static Data Member

The information in this article applies to:

• Microsoft Visual C++, 32-bit Edition, versions 2.0, 2.1, 2.2

SYMPTOMS

A template class that contains a static data member of a type that was not pre-defined, such as a struct or a class, causes this error:

   C2985 <var name> : invalid static data member; template class < template
   class name> already has a function member of the same name.

RESOLUTION

Explicitly initialize the static data member when it is declared. This may require adding a constructor to the structure (see the sample code).

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 Microsoft Visual C++, 32-bit Edition, version 4.0.

Sample Code

/* Compile options needed: None (compiler defaults will do)
*/

//   A() {}  // ctor added for explicit initialization
   void some_funct(){}

template <class T> struct B {

    static A static_member;
    void func() { static_member.some_funct(); }

// error will occur on the following line:

void main()

   B<int> b;

   b.func();

This code, as shown, generates the error. To work around the problem, change the line where A() is declared and defined from a comment into an executed line, and do the same for the = A() on the line where the error is occurring. This explicitly initializes the data member when it is declared.