error[E0521]: borrowed data escapes outside of closure --> $DIR/issue-7573.rs:17:9 | LL | let mut lines_to_use: Vec<&CrateId> = Vec::new(); | ---------------- `lines_to_use` declared here, outside of the closure body LL | LL | let push_id = |installed_id: &CrateId| { | ------------ `installed_id` is a reference that is only valid in the closure body LL | LL | lines_to_use.push(installed_id); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `installed_id` escapes the closure body here error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0521`.