Pure opEquals in a class

[werter via Digitalmars-d-learn]

The code below doesn't work. Is it possible to make a pure 
opEquals in a class?

void main()
{
        class A
        {
                bool a;
                int b;
                
                this(bool g, int h)
                {
                        a = g;
                        b = h;
                }
                                
                pure bool opEquals(const A rhs) const
                {
                        return b == rhs.b;      
                }               
        }
                
        A a = new A(true, 5);
        A b = new A(false, 5);
        
        assert(a == b); //fails
}