Rollup merge of #139773 - thaliaarchi:vec-into-iter-last, r=workingjubilee

Implement `Iterator::last` for `vec::IntoIter`

Avoid iterating everything when we have random access to the last element.

1 files changed, 5 insertions, 0 deletions

diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
index 1af110691ba..37df928228d 100644
--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
@@ -259,6 +259,11 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
     }
 
     #[inline]
+    fn last(mut self) -> Option<T> {
+        self.next_back()
+    }
+
+    #[inline]
     fn next_chunk<const N: usize>(&mut self) -> Result<[T; N], core::array::IntoIter<T, N>> {
         let mut raw_ary = [const { MaybeUninit::uninit() }; N];