1 error[E0658]: use of unstable library feature 'issue_52489_unstable'
2 --> $DIR/issue-52489.rs:15:5
7 = help: add #![feature(issue_52489_unstable)] to the crate attributes to enable
9 error: aborting due to previous error
11 For more information about this error, try `rustc --explain E0658`.