// This test should never pass! #![feature(type_alias_impl_trait)] pub trait Captures<'a> {} impl Captures<'_> for T {} pub struct MyTy<'a, 'b>(Option<*mut &'a &'b ()>); unsafe impl Send for MyTy<'_, 'static> {} pub mod step1 { use super::*; pub type Step1<'a, 'b: 'a> = impl Sized + Captures<'b> + 'a; pub fn step1<'a, 'b: 'a>() -> Step1<'a, 'b> { MyTy::<'a, 'b>(None) } } pub mod step2 { pub type Step2<'a> = impl Send + 'a; // Although `Step2` is WF at the definition site, it's not WF in its // declaration site (above). We check this in `check_opaque_meets_bounds`, // which must remain sound. pub fn step2<'a, 'b: 'a>() -> Step2<'a> where crate::step1::Step1<'a, 'b>: Send { crate::step1::step1::<'a, 'b>() //~^ ERROR hidden type for `Step2<'a>` captures lifetime that does not appear in bounds } } fn step3<'a, 'b>() { fn is_send() {} is_send::>(); } fn main() {}