src/test/ui/issues/issue-3154.rs

struct Thing<'a, Q:'a> {
    x: &'a Q
}

fn thing<'a,Q>(x: &Q) -> Thing<'a,Q> {
    Thing { x: x } //~ ERROR explicit lifetime required in the type of `x` [E0621]
}

fn main() {
    thing(&());
}