rust/tests/run-pass/ice-2774.rs

use std::collections::HashSet;

// See https://github.com/rust-lang/rust-clippy/issues/2774

#[derive(Eq, PartialEq, Debug, Hash)]
pub struct Bar {
    foo: Foo,
}

#[derive(Eq, PartialEq, Debug, Hash)]
pub struct Foo {}

#[allow(clippy::implicit_hasher)]
// This should not cause a 'cannot relate bound region' ICE
pub fn add_barfoos_to_foos<'a>(bars: &HashSet<&'a Bar>) {
    let mut foos = HashSet::new();
    foos.extend(bars.iter().map(|b| &b.foo));
}

#[allow(clippy::implicit_hasher)]
// Also this should not cause a 'cannot relate bound region' ICE
pub fn add_barfoos_to_foos2(bars: &HashSet<&Bar>) {
    let mut foos = HashSet::new();
    foos.extend(bars.iter().map(|b| &b.foo));
}

fn main() {}