#![feature(const_default_impls)]
#![feature(const_trait_impl)]
#![feature(if_let_guard)]
-#![cfg_attr(bootstrap, feature(label_break_value))]
#![feature(let_chains)]
-#![cfg_attr(bootstrap, feature(let_else))]
#![feature(min_specialization)]
#![feature(negative_impls)]
#![feature(slice_internals)]