I have this code :

trait State:

    fn to_string(self) -> String:
        ...

struct StateTtt(State):

    fn __init__(inout self):
        pass

    fn to_string(self) -> String:
        return "ABC"

fn get_state() -> State:
    return StateTtt()

fn main():
    var s = get_state()
    print(s.to_string())

But it gives me the error :

“cannot implicitly convert ‘StateTtt’ value to ‘State’ in return value”

But the StateTtt struct implements the State trait, so why it cannot be converted ?

Of course this is a simplified version of my code. In the real code the getState function will create a struct instance based on a paramenter.