Implicit conversion from array of class to array of interface

[Phil Deets]

(D 2.033) I have a need to do something like this code:
interface I {}
class C : I {}
class D : I {}

void f(I[]) {}
void f(bool) {}

void g(T)(T param) {
        f(param);
}

int main()
{
        bool b;
        C[] c;
        D[] d;
        g(b);
        g(c);
        g(d);
        return 0;
}

This results in the output:

temp.d(9): Error: function temp.f (I[] _param_0) is not callable using  
argument types (C[])
temp.d(9): Error: cannot implicitly convert expression (param) of type C[]  
to bool
temp.d(18): Error: template instance temp.g!(C[]) error instantiating

As you can see, I can't cast C[] to I[] when I call f because T can be  
bool too. My workaround for now is:

interface I {}
class C : I {}
class D : I {}

void f(I[]) {}
void f(C[] param) {
        f(cast(I[])param);
}
void f(D[] param) {
        f(cast(I[])param);
}
void f(bool) {}

void g(T)(T param) {
        f(param);
}

int main()
{
        bool b;
        C[] c;
        D[] d;
        g(b);
        g(c);
        g(d);
        return 0;
}

Is there a better way to deal with this? Is this behavior a design bug?

Phil Deets

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