error[E0721]: `await` is a keyword in the 2018 edition
  --> $DIR/post_expansion_error.rs:8:5
   |
LL |     await!()
   |     ^^^^^ help: you can use a raw identifier to stay compatible: `r#await`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0721`.