diff --git a/compiler/rustc_ast/src/ptr.rs b/compiler/rustc_ast/src/ptr.rs
index 0140fb752bf92..3308849f92061 100644
--- a/compiler/rustc_ast/src/ptr.rs
+++ b/compiler/rustc_ast/src/ptr.rs
@@ -186,7 +186,7 @@ impl<'a, T> IntoIterator for &'a P<[T]> {
     type Item = &'a T;
     type IntoIter = slice::Iter<'a, T>;
     fn into_iter(self) -> Self::IntoIter {
-        self.ptr.into_iter()
+        self.ptr.iter()
     }
 }
 
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 96b93830f9600..acb50760bfe7e 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -163,6 +163,7 @@ use core::ops::{
 };
 use core::pin::Pin;
 use core::ptr::{self, NonNull, Unique};
+use core::slice;
 use core::task::{Context, Poll};
 
 #[cfg(not(no_global_oom_handling))]
@@ -175,6 +176,7 @@ use crate::raw_vec::RawVec;
 use crate::str::from_boxed_utf8_unchecked;
 #[cfg(not(no_global_oom_handling))]
 use crate::string::String;
+use crate::vec;
 #[cfg(not(no_global_oom_handling))]
 use crate::vec::Vec;
 
@@ -2036,6 +2038,42 @@ impl<I> FromIterator<I> for Box<[I]> {
     }
 }
 
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<I, A: Allocator> !Iterator for Box<[I], A> {}
+
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<I, A: Allocator> IntoIterator for Box<[I], A> {
+    type IntoIter = vec::IntoIter<I, A>;
+    type Item = I;
+    fn into_iter(self) -> vec::IntoIter<I, A> {
+        self.into_vec().into_iter()
+    }
+}
+
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, I, A: Allocator> !Iterator for &'a Box<[I], A> {}
+
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, I, A: Allocator> IntoIterator for &'a Box<[I], A> {
+    type IntoIter = slice::Iter<'a, I>;
+    type Item = &'a I;
+    fn into_iter(self) -> slice::Iter<'a, I> {
+        self.iter()
+    }
+}
+
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, I, A: Allocator> !Iterator for &'a mut Box<[I], A> {}
+
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, I, A: Allocator> IntoIterator for &'a mut Box<[I], A> {
+    type IntoIter = slice::IterMut<'a, I>;
+    type Item = &'a mut I;
+    fn into_iter(self) -> slice::IterMut<'a, I> {
+        self.iter_mut()
+    }
+}
+
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "box_slice_clone", since = "1.3.0")]
 impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A> {
diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index 5e229bf524411..ccfe5e9c16d0a 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -17,6 +17,9 @@ use crate::ptr::{self, invalid, invalid_mut, NonNull};
 
 use super::{from_raw_parts, from_raw_parts_mut};
 
+#[stable(feature = "boxed_slice_into_iter", since = "CURRENT_RUSTC_VERSION")]
+impl<T> !Iterator for [T] {}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> IntoIterator for &'a [T] {
     type Item = &'a T;