How can I induce implicit type convesion with alias this on calling template function?

[Sobaya]

void func(T : int)(T value) if (is(T == int)) {
}

struct S {
     int x;
     alias x this;
}

void main() {
     func(S()); // error
}

In above code, 'func' can accept only int as its argument type, 
so when 'S', which can be implicitly convertible into int, is 
passed on 'func', I expect S.x is passed, but this function call 
is failed.

Is there any way to solve it with keeping 'func' template 
function?