#![crate_type = "lib"]
#![feature(associated_types)]
#![no_implicit_prelude]

trait Iterator {
    type Item;
}

trait AdditiveIterator {
    type Sum;

    fn sum(self) -> Self::Sum;
}

impl<I> AdditiveIterator for I where I: Iterator<Item=u8> {  //~error conflicting implementation
    type Sum = u8;

    fn sum(self) -> u8 { loop {} }
}

impl<I> AdditiveIterator for I where I: Iterator<Item=u16> {  //~note conflicting implementation here
    type Sum = u16;

    fn sum(self) -> u16 { loop {} }
}