error[E0658]: use of unstable library feature 'unstable_test_feature'
  --> $DIR/lint-output-format.rs:6:1
   |
LL | extern crate lint_output_format;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: add `#![feature(unstable_test_feature)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'unstable_test_feature'
  --> $DIR/lint-output-format.rs:7:31
   |
LL | use lint_output_format::{foo, bar};
   |                               ^^^
   |
   = help: add `#![feature(unstable_test_feature)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'unstable_test_feature'
  --> $DIR/lint-output-format.rs:11:14
   |
LL |     let _y = bar();
   |              ^^^
   |
   = help: add `#![feature(unstable_test_feature)]` to the crate attributes to enable

error: aborting due to 3 previous errors

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