error[E0635]: unknown feature `const_fn_trait_ref_impls` --> $DIR/fn_trait_refs.rs:3:12 | LL | #![feature(const_fn_trait_ref_impls)] | ^^^^^^^^^^^^^^^^^^^^^^^^ error[E0635]: unknown feature `const_cmp` --> $DIR/fn_trait_refs.rs:8:12 | LL | #![feature(const_cmp)] | ^^^^^^^^^ error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0635`.