Rollup merge of #89053 - DeveloperC286:into_iter_fields_to_private, r=Mark-Simulacrum

refactor: VecDeques IntoIter fields to private

Made the fields of VecDeque's IntoIter private by creating a IntoIter::from(...) function to create a new instance of IntoIter and migrating usage to use IntoIter::from(...).

library/alloc/src/collections/vec_deque/into_iter.rs

@@ -17,7 +17,13 @@ pub struct IntoIter<
     T,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
 > {
-    pub(crate) inner: VecDeque<T, A>,
+    inner: VecDeque<T, A>,
+}
+
+impl<T, A: Allocator> IntoIter<T, A> {
+    pub(super) fn new(inner: VecDeque<T, A>) -> Self {
+        IntoIter { inner }
+    }
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]

library/alloc/src/collections/vec_deque/mod.rs

@@ -2827,7 +2827,7 @@ impl<T, A: Allocator> IntoIterator for VecDeque<T, A> {
     /// Consumes the `VecDeque` into a front-to-back iterator yielding elements by
     /// value.
     fn into_iter(self) -> IntoIter<T, A> {
-        IntoIter { inner: self }
+        IntoIter::new(self)
     }
 }