opCast + dtor error

[vit]

Hi, why this code doesn't compile?

```d
struct Foo{
     bool opCast(T : bool)()const{
         assert(0);
     }

     ~this(){}
}

struct Bar{
     const Foo foo;
}

void main(){


}
```

Error: template instance `opCast!(Foo)` does not match template 
declaration `opCast(T : bool)()`