class A{}

void main ()
{
     A a,b;
     a=new A;
     b=new A;
     writefln(a==b);
     writefln(a<b);
     writefln(a+b);
     writefln(a-b);
     writefln(a*b); //'a' is not an arithmetic type
}

WHY? Why don't the first four writefln's couse error messages from compiler!

I see it as a huge problem for generic programming!
For example: this template will work for the above A class
an any other class you write, even if you don't provide an opAdd
operator!

template func(Type)
{
    Type func(Type a, Type b)
    {
        return a+b;
     }
}

>      writefln(a+b);
>      writefln(a-b);

These two should error but do pointer arithmetic instead. That seems like a bug.

The a==b and a<b are working as designed but by your post on the main newsgroup I think you'd like to see the design changed - which is different than the a+b and a-b examples.