conflicting_implementation.rs

trait FnRegister<A, RetVal, Args> {
    fn register(&mut self, name: &str, f: A);
}

impl<A, RetVal, Arg1> FnRegister<A, RetVal, (Arg1,)> for Bob
    where A: 'static + Fn(Arg1)->RetVal
{
    fn register(self, name: &str, fun: fn(Arg1)->RetVal) {
        println!("Fn(T)->U");
    }
}

impl<'a, A, RetVal, Arg1> FnRegister<A, RetVal, (&'a Arg1,)> for Bob
    where A: 'static + Fn(&Arg1)->RetVal
{
    fn register(self, name: &str, fun: fn(&Arg1)->RetVal) {
        println!("Fn(&T)->U");
    }
}

struct Bob { x: u32 }
impl Bob {
    fn bob_val(self) {
        println!("bob_val");
    }
    fn bob_ref(&self) {
        println!("bob_ref");
    }
}

fn main() {
    let mut bob = Bob { x: 1 };

    bob.register("bob_val", Bob::bob_val);
    bob.register("bob_ref", Bob::bob_ref);
}

/*
error: conflicting implementations of trait `FnRegister<_, _, (&_,)>` for type `Bob`: [--explain E0119]
  --> testme.rs:13:1
13 |> impl<'a, A, RetVal, Arg1> FnRegister<A, RetVal, (&'a Arg1,)> for Bob
   |> ^
note: conflicting implementation is here:
 --> testme.rs:5:1
5 |> impl<A, RetVal, Arg1> FnRegister<A, RetVal, (Arg1,)> for Bob
  |> ^
*/