typeof(func!0) != typeof(func!0())

[Andrey Zherikov via Digitalmars-d-learn]

I have this simple code:
```d
struct U
{
    auto ref func(int i)() { return this; }
}
void main()
{
    {
        alias type = typeof(U().func!0);
        pragma(msg, type);  		// pure nothrow @nogc ref @safe U() 
return
        pragma(msg, is(type : U));  // false

        auto u = U().func!0;
        pragma(msg, typeof(u));         // U
    }
    {
        alias type = typeof(U().func!0());
        pragma(msg, type);              // U
        pragma(msg, is(type : U));  // true

        auto u = U().func!0();
        pragma(msg, typeof(u));         // U
    }
}
```
Why does `typeof(U().func!0)` != `U`? How can I check that the 
returned value has type `U` in this case?