From afcee19d88658e54f4a3c82892ba6d937e0f78d4 Mon Sep 17 00:00:00 2001
From: Caleb Sander <caleb.sander@gmail.com>
Date: Wed, 20 Oct 2021 17:04:01 -0700
Subject: [PATCH] Make RSplit<T, P>: Clone not require T: Clone

This addresses a TODO comment. The behavior of #[derive(Clone)]
*does* result in a T: Clone requirement.

Add a manual Clone implementation, matching Split and SplitInclusive.
---
 library/core/src/slice/iter.rs        | 12 +++++++++++-
 src/test/ui/iterators/rsplit-clone.rs | 11 +++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/iterators/rsplit-clone.rs

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index dbf97851b03..07ecae78303 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -839,7 +839,6 @@ impl<T, P> FusedIterator for SplitInclusiveMut<'_, T, P> where P: FnMut(&T) -> b
 /// [`rsplit`]: slice::rsplit
 /// [slices]: slice
 #[stable(feature = "slice_rsplit", since = "1.27.0")]
-#[derive(Clone)] // Is this correct, or does it incorrectly require `T: Clone`?
 pub struct RSplit<'a, T: 'a, P>
 where
     P: FnMut(&T) -> bool,
@@ -867,6 +866,17 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
+// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
+#[stable(feature = "slice_rsplit", since = "1.27.0")]
+impl<T, P> Clone for RSplit<'_, T, P>
+where
+    P: Clone + FnMut(&T) -> bool,
+{
+    fn clone(&self) -> Self {
+        RSplit { inner: self.inner.clone() }
+    }
+}
+
 #[stable(feature = "slice_rsplit", since = "1.27.0")]
 impl<'a, T, P> Iterator for RSplit<'a, T, P>
 where
diff --git a/src/test/ui/iterators/rsplit-clone.rs b/src/test/ui/iterators/rsplit-clone.rs
new file mode 100644
index 00000000000..911da742957
--- /dev/null
+++ b/src/test/ui/iterators/rsplit-clone.rs
@@ -0,0 +1,11 @@
+// check-pass
+
+// RSplit<T, P> previously required T: Clone in order to be Clone
+
+struct NotClone;
+
+fn main() {
+    let elements = [NotClone, NotClone, NotClone];
+    let rsplit = elements.rsplit(|_| false);
+    rsplit.clone();
+}