Add requisite feature gates in the standard library

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 49cec16276260ad81b5e74fd13a090828df162cc..d96e82f1d5e6dd88179a6d9b1c3ddc315a8352ec 100644 (file)
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -83,6 +83,7 @@
 #![feature(const_fn)]
 #![feature(const_fn_union)]
 #![feature(const_assume)]
+#![cfg_attr(not(bootstrap), feature(const_fn_impl_trait))]
 #![cfg_attr(not(bootstrap), feature(const_fn_floating_point_arithmetic))]
 #![cfg_attr(not(bootstrap), feature(const_fn_fn_ptr_basics))]
 #![feature(const_generics)]