error: `extern crate` is not idiomatic in the new edition
  --> $DIR/extern-crate-used.rs:8:1
   |
LL | extern crate core as iso1; //~ ERROR `extern crate` is not idiomatic in the new edition
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`
   |
note: lint level defined here
  --> $DIR/extern-crate-used.rs:6:9
   |
LL | #![deny(unused_extern_crates)]
   |         ^^^^^^^^^^^^^^^^^^^^

error: `extern crate` is not idiomatic in the new edition
  --> $DIR/extern-crate-used.rs:9:1
   |
LL | extern crate core as iso2; //~ ERROR `extern crate` is not idiomatic in the new edition
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`

error: `extern crate` is not idiomatic in the new edition
  --> $DIR/extern-crate-used.rs:10:1
   |
LL | extern crate core as iso3; //~ ERROR `extern crate` is not idiomatic in the new edition
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`

error: `extern crate` is not idiomatic in the new edition
  --> $DIR/extern-crate-used.rs:11:1
   |
LL | extern crate core as iso4; //~ ERROR `extern crate` is not idiomatic in the new edition
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`

error: unused extern crate
  --> $DIR/extern-crate-used.rs:14:1
   |
LL | extern crate core; //~ ERROR unused extern crate
   | ^^^^^^^^^^^^^^^^^^ help: remove it

error: aborting due to 5 previous errors