#![feature(const_fn)]
#![feature(crate_visibility_modifier)]
#![feature(custom_attribute)]
-#![cfg_attr(not(stage0), feature(nll))]
+#![feature(nll)]
#![feature(non_exhaustive)]
#![feature(optin_builtin_traits)]
#![feature(specialization)]
-#![feature(stdsimd)]
+#![cfg_attr(not(stage0), feature(stdsimd))]
use std::borrow::Cow;
use std::cell::Cell;