src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs-2.rs

struct Ref<'a, 'b> {
    a: &'a u32,
    b: &'b u32,
}

fn foo(mut x: Ref, y: Ref) {
    x.b = y.b; //~ ERROR lifetime mismatch
}

fn main() {}