// run-pass // check that the derived impls for the comparison traits shortcircuit // where possible, by having a type that panics when compared as the // second element, so this passes iff the instances shortcircuit. use std::cmp::Ordering; pub struct FailCmp; impl PartialEq for FailCmp { fn eq(&self, _: &FailCmp) -> bool { panic!("eq") } } impl PartialOrd for FailCmp { fn partial_cmp(&self, _: &FailCmp) -> Option { panic!("partial_cmp") } } impl Eq for FailCmp {} impl Ord for FailCmp { fn cmp(&self, _: &FailCmp) -> Ordering { panic!("cmp") } } #[derive(PartialEq,PartialOrd,Eq,Ord)] struct ShortCircuit { x: isize, y: FailCmp } pub fn main() { let a = ShortCircuit { x: 1, y: FailCmp }; let b = ShortCircuit { x: 2, y: FailCmp }; assert!(a != b); assert!(a < b); assert_eq!(a.cmp(&b), ::std::cmp::Ordering::Less); }