error[E0658]: the `#[fundamental]` attribute is an experimental feature --> $DIR/feature-gate-fundamental.rs:1:1 | LL | #[fundamental] | ^^^^^^^^^^^^^^ | = note: see issue #29635 for more information = help: add `#![feature(fundamental)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.