error[E0637]: `'_` cannot be used here
  --> $DIR/issue-70304.rs:47:41
   |
LL | fn create_doc() -> impl Document<Cursor<'_> = DocCursorImpl<'_>> {
   |                                         ^^ `'_` is a reserved lifetime name

error[E0106]: missing lifetime specifier
  --> $DIR/issue-70304.rs:47:61
   |
LL | fn create_doc() -> impl Document<Cursor<'_> = DocCursorImpl<'_>> {
   |                                                             ^^ expected named lifetime parameter
   |
   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
help: consider using the `'static` lifetime
   |
LL | fn create_doc() -> impl Document<Cursor<'_> = DocCursorImpl<'static>> {
   |                                                             ~~~~~~~

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0106, E0637.
For more information about an error, try `rustc --explain E0106`.