IFTI in Eponymous Templates

[jmh530 via Digitalmars-d-learn]

I was playing around with some Eponymous Templates. I had been 
under the impression that Implicit Function-Template 
Instantiation (IFTI) meant that you don't have to explicitly 
instantiate all functions. However, it seems like there are cases 
with eponymous templates with functions in them that you do. For 
instance, in the bar function below, I have to explicitly 
instantiate the inner function template.

template foo(T, U)
{
        T foo(T x, U y)
        {
                return x + cast(T)y;
        }
}

template bar(T)
{
        T bar(U)(T x, U y)
        {
                return x + cast(T)y;
        }
}

void main()
{
        int a = 1;
        long b = 2;
        auto x = foo(a, a);
        //auto y = bar(a, b); //error
        auto y = bar!(long)(a, b);
}