Consider this two-file project:

// test.d
import testmod;

void main()
{
    void whatever() {}
    foo!(whatever)();
}

// testmod.d
private void bar(alias a)() {}

void foo(alias a)() {
    .bar!(a)();
}

Compiling test.d yields:

testmod.d(5): Error: function test.bar is not accessible from testmod
test.d(6): template instance test.main.foo!(whatever) error instantiating

(I thought I submitted this once, but I couldn't find it.)