error[E0658]: use of unstable library feature 'data'
  --> $DIR/assoc-inherent-unstable.rs:4:13
   |
LL | type Data = aux::Owner::Data;
   |             ^^^^^^^^^^^^^^^^
   |
   = help: add `#![feature(data)]` to the crate attributes to enable

error: aborting due to previous error

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