error: ambiguous lifetime bound in `impl Trait` --> $DIR/feature-gate-member-constraints.rs:4:43 | LL | fn foo<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Trait<'a, 'b> { | ^^^^^^^^^^^^^^^^^^ neither `'a` nor `'b` outlives the other | = help: add #![feature(member_constraints)] to the crate attributes to enable error: ambiguous lifetime bound in `impl Trait` --> $DIR/feature-gate-member-constraints.rs:4:43 | LL | fn foo<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Trait<'a, 'b> { | ^^^^^^^^^^^^^^^^^^ the elided lifetimes here do not outlive one another | = help: add #![feature(member_constraints)] to the crate attributes to enable error: aborting due to 2 previous errors