error[E0599]: no method named `test` found for opaque type `impl Future<Output = A>` in the current scope
  --> $DIR/dont-suggest-await-on-method-return-mismatch.rs:18:24
   |
LL |     let x: u32 = foo().test();
   |                        ^^^^ method not found in `impl Future<Output = A>`
   |
help: consider `await`ing on the `Future` and calling the method on its `Output`
   |
LL |     let x: u32 = foo().await.test();
   |                        ++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0599`.