message: add async fn with partial initialization
diff: -#![feature(async_await)]
  +#![feature(async_await, never_type)]
  use std::{future::Future, pin::Pin, task::Poll, ptr};
  use std::task::{Waker, RawWaker, RawWakerVTable, Context};
  @@ -40,6 +40,11 @@ async fn includes_never(crash: bool, x: u32) -> u32 {
  result
  }
  +async fn partial_init(x: u32) -> u32 {
  + #[allow(unreachable_code)]
  + let _x: (String, !) = (String::new(), return async { x + x }.await);
  +}
  +
  fn run_fut(mut fut: impl Future<Output=u32>, output: u32) {
  fn raw_waker_clone(_this: *const ()) -> RawWaker {
  panic!("unimplemented");
  @@ -71,4 +76,6 @@ fn main() {
  run_fut(build_aggregate(1, 2, 3, 4), 10);
  run_fut(includes_never(false, 4), 16);
  +
  + run_fut(partial_init(4), 8);
  }
  