1 files changed, 46 insertions, 0 deletions
diff --git a/tests/ui/iterators/into-iter-on-boxed-slices-2021.rs b/tests/ui/iterators/into-iter-on-boxed-slices-2021.rs
new file mode 100644
index 00000000000..3d9d131e59c
--- /dev/null
+++ b/tests/ui/iterators/into-iter-on-boxed-slices-2021.rs
@@ -0,0 +1,46 @@
+//@ check-pass
+//@ edition:2018
+
+use std::ops::Deref;
+use std::rc::Rc;
+use std::slice::Iter;
+use std::vec::IntoIter;
+
+fn main() {
+    let boxed_slice = vec![0; 10].into_boxed_slice();
+
+    // Before 2024, the method dispatched to `IntoIterator for Box<[T]>`,
+    // which we continue to support for compatibility.
+    let _: Iter<'_, i32> = boxed_slice.into_iter();
+    //~^ WARNING this method call resolves to `<&Box<[T]> as IntoIterator>::into_iter`
+    //~| WARNING this changes meaning
+
+    let _: Iter<'_, i32> = Box::new(boxed_slice.clone()).into_iter();
+    //~^ WARNING this method call resolves to `<&Box<[T]> as IntoIterator>::into_iter`
+    //~| WARNING this changes meaning
+
+    let _: Iter<'_, i32> = Rc::new(boxed_slice.clone()).into_iter();
+    //~^ WARNING this method call resolves to `<&Box<[T]> as IntoIterator>::into_iter`
+    //~| WARNING this changes meaning
+    let _: Iter<'_, i32> = Array(boxed_slice.clone()).into_iter();
+    //~^ WARNING this method call resolves to `<&Box<[T]> as IntoIterator>::into_iter`
+    //~| WARNING this changes meaning
+
+    // But you can always use the trait method explicitly as an boxed_slice.
+    let _: IntoIter<i32> = IntoIterator::into_iter(boxed_slice);
+
+    for _ in (Box::new([1, 2, 3]) as Box<[_]>).into_iter() {}
+    //~^ WARNING this method call resolves to `<&Box<[T]> as IntoIterator>::into_iter`
+    //~| WARNING this changes meaning
+}
+
+/// User type that dereferences to a boxed slice.
+struct Array(Box<[i32]>);
+
+impl Deref for Array {
+    type Target = Box<[i32]>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}