-#![feature(const_fn_fn_ptr_basics)]
-#![feature(const_fn_trait_bound)]
-#![feature(const_impl_trait)]
+#![cfg_attr(bootstrap, feature(const_fn_fn_ptr_basics))]
+#![cfg_attr(bootstrap, feature(const_fn_trait_bound))]
+#![cfg_attr(bootstrap, feature(const_impl_trait))]