// this used to cause stack overflows trait Hrtb<'a> { type Assoc; } impl<'a> Hrtb<'a> for () { type Assoc = (); } impl<'a> Hrtb<'a> for &'a () { type Assoc = (); } fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {} //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> { //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet &() } fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> { //~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet x } fn main() {}