error[E0658]: the `#[no_core]` attribute is an experimental feature --> $DIR/feature-gate-no_core.rs:3:1 | LL | #![no_core] | ^^^^^^^^^^^ | = note: see issue #29639 for more information = help: add `#![feature(no_core)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.