error[E0521]: borrowed data escapes outside of function
  --> $DIR/resume-arg-outlives-2.rs:20:5
   |
LL | fn demo<'not_static>(s: &'not_static str) -> thread::JoinHandle<()> {
   |         -----------  - `s` is a reference that is only valid in the function body
   |         |
   |         lifetime `'not_static` defined here
...
LL |     generator.as_mut().resume(s); // <- generator hoards it as `let ctx`.
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |     |
   |     `s` escapes the function body here
   |     argument requires that `'not_static` must outlive `'static`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0521`.