FIX: 'using' Declaration Doesn't Overload Base Class Members

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This article was previously published under Q140604

SYMPTOMS

Attempting to overload member functions located in a base class from a derived class with a 'using' declaration, may result in the following compiler error:

error C2664: 'function': cannot convert parameter 'number' from 'type1' to 'type2'

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CAUSE

This particular problem occurs if the member functions that are being overloaded are declared before the 'using' declaration in the class definition.

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RESOLUTION

Place the 'using' declaration above the declarations for the member functions you want to overload. See the comments in the following code sample:

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Sample Code

#include "iostream.h"

class A
{
public:
   int f(int) {cout << "In A::f(int)!!!\n";return 0;}
};

class B : public A
{
public:
   int f(char*){cout << "In D::f(char*)!!!\n";return 0;}
   using A::f;        // <<== move this above the int f(char*)
                      //  declaration to fix the problem.
};

void main()
{
   B d;
   d.A::f(1);
   d.f(1);            // <<== C2664 happens here
   d.f("Hi There");
}

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STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

This problem was corrected in Microsoft Visual C++ .NET.

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