From ba05b764bcb776c0c732d058e0a0d1ac99c5facb Mon Sep 17 00:00:00 2001
From: Astra Tsai <astra@ucsc.edu>
Date: Mon, 1 Jul 2024 19:00:10 -0700
Subject: [PATCH] Add regression test for #12964

---
 tests/ui/into_iter_without_iter.rs | 39 ++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tests/ui/into_iter_without_iter.rs b/tests/ui/into_iter_without_iter.rs
index c8b907604..109259d69 100644
--- a/tests/ui/into_iter_without_iter.rs
+++ b/tests/ui/into_iter_without_iter.rs
@@ -185,3 +185,42 @@ pub mod issue11635 {
         }
     }
 }
+
+pub mod issue12964 {
+    pub struct MyIter<'a, T: 'a> {
+        iter: std::slice::Iter<'a, T>,
+    }
+
+    impl<'a, T> Iterator for MyIter<'a, T> {
+        type Item = &'a T;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            self.iter.next()
+        }
+    }
+
+    pub struct MyContainer<T> {
+        inner: Vec<T>,
+    }
+
+    impl<T> MyContainer<T> {}
+
+    impl<T> MyContainer<T> {
+        #[must_use]
+        pub fn iter(&self) -> MyIter<'_, T> {
+            <&Self as IntoIterator>::into_iter(self)
+        }
+    }
+
+    impl<'a, T> IntoIterator for &'a MyContainer<T> {
+        type Item = &'a T;
+
+        type IntoIter = MyIter<'a, T>;
+
+        fn into_iter(self) -> Self::IntoIter {
+            Self::IntoIter {
+                iter: self.inner.as_slice().iter(),
+            }
+        }
+    }
+}