Build on current nightly

core/src/lib.rs

@@ -2,10 +2,8 @@
 #![feature(const_ops)]
 #![feature(const_trait_impl)]
 #![feature(const_convert)]
-#![feature(map_try_insert)]
 #![feature(unboxed_closures)]
 #![feature(fn_traits)]
-#![feature(const_cmp)]
 #![feature(const_destruct)]
 #![feature(portable_simd)]
 #![feature(associated_type_defaults)]