error[E0658]: unadjusted ABI is an implementation detail and perma-unstable
  --> $DIR/feature-gate-abi_unadjusted.rs:11:1
   |
LL | / extern "unadjusted" fn foo() {
LL | | //~^ ERROR: unadjusted ABI is an implementation detail and perma-unstable
LL | | }
   | |_^
   |
   = help: add #![feature(abi_unadjusted)] to the crate attributes to enable

error: aborting due to previous error

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