error[E0658]: use of unstable library feature 'issue_52489_unstable'
  --> $DIR/issue-52489.rs:5:5
   |
LL | use issue_52489;
   |     ^^^^^^^^^^^
   |
   = help: add #![feature(issue_52489_unstable)] to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.