rust/tests/ui/traits/inheritance/diamond.rs

// run-pass
#![allow(dead_code)]
// B and C both require A, so D does as well, twice, but that's just fine


trait A { fn a(&self) -> isize; }
trait B: A { fn b(&self) -> isize; }
trait C: A { fn c(&self) -> isize; }
trait D: B + C { fn d(&self) -> isize; }

struct S { bogus: () }

impl A for S { fn a(&self) -> isize { 10 } }
impl B for S { fn b(&self) -> isize { 20 } }
impl C for S { fn c(&self) -> isize { 30 } }
impl D for S { fn d(&self) -> isize { 40 } }

fn f<T:D>(x: &T) {
    assert_eq!(x.a(), 10);
    assert_eq!(x.b(), 20);
    assert_eq!(x.c(), 30);
    assert_eq!(x.d(), 40);
}

pub fn main() {
    let value = &S { bogus: () };
    f(value);
}