Make EncodeWide implement FusedIterator

Author: AronParker

library/std/src/sys_common/wtf8.rs

@@ -25,7 +25,7 @@ use crate::char;
 use crate::collections::TryReserveError;
 use crate::fmt;
 use crate::hash::{Hash, Hasher};
-use crate::iter::FromIterator;
+use crate::iter::{FromIterator, FusedIterator};
 use crate::mem;
 use crate::ops;
 use crate::rc::Rc;
@@ -899,6 +899,9 @@ impl<'a> Iterator for EncodeWide<'a> {
     }
 }
 
+#[stable(feature = "encode_wide_fused_iterator", since = "1.62.0")]
+impl FusedIterator for EncodeWide<'_> {}
+
 impl Hash for CodePoint {
     #[inline]
     fn hash<H: Hasher>(&self, state: &mut H) {