src/test/ui/nll/issue-52742.rs

#![feature(nll)]
#![feature(in_band_lifetimes)]

struct Foo<'a, 'b> {
    x: &'a u32,
    y: &'b u32,
}

struct Bar<'b> {
    z: &'b u32
}

impl Foo<'_, '_> {
    fn take_bar(&mut self, b: Bar<'_>) {
        self.y = b.z
        //~^ ERROR unsatisfied lifetime constraints
    }
}

fn main() { }