warning: unused extern crate
  --> $DIR/removing-extern-crate.rs:19:1
   |
LL | extern crate std as foo;
   | ^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
   |
note: lint level defined here
  --> $DIR/removing-extern-crate.rs:16:9
   |
LL | #![warn(rust_2018_idioms)]
   |         ^^^^^^^^^^^^^^^^
   = note: #[warn(unused_extern_crates)] implied by #[warn(rust_2018_idioms)]

warning: unused extern crate
  --> $DIR/removing-extern-crate.rs:20:1
   |
LL | extern crate core;
   | ^^^^^^^^^^^^^^^^^^ help: remove it

warning: unused extern crate
  --> $DIR/removing-extern-crate.rs:23:5
   |
LL |     extern crate std as foo;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it

warning: unused extern crate
  --> $DIR/removing-extern-crate.rs:24:5
   |
LL |     extern crate std;
   |     ^^^^^^^^^^^^^^^^^ help: remove it