error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
  --> $DIR/issue-91477.rs:4:5
   |
LL |     yield 1;
   |     ^^^^^^^
   |
help: use `#[coroutine]` to make this closure a coroutine
   |
LL | #[coroutine] fn foo() -> impl Sized {
   | ++++++++++++

error[E0627]: yield expression outside of coroutine literal
  --> $DIR/issue-91477.rs:4:5
   |
LL |     yield 1;
   |     ^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0627`.