From 15bc9b6d81a7c9f65d7b8b3224d0d552d051cd7a Mon Sep 17 00:00:00 2001
From: Alexis Bourget <alexis.bourget@gmail.com>
Date: Sat, 4 Jul 2020 23:50:01 +0200
Subject: [PATCH 1/3] First version of contains_ref

---
 library/core/src/slice/mod.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 9ed5a1f962215..09591aa3ff119 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -1407,6 +1407,23 @@ impl<T> [T] {
         x.slice_contains(self)
     }
 
+    /// Returns `true` if the slice contains an element with the given value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = [String::from("Hello"), String::from("world")];
+    /// assert!(v.contains_ref("Hello"));
+    /// assert!(!v.contains_ref("Rust"));
+    /// ```
+    #[unstable(feature = "contains_ref", issue = "none")]
+    pub fn contains_ref<U>(&self, x: &U) -> bool
+    where
+        T: PartialEq<U>,
+    {
+        self.iter().any(|e| e == x)
+    }
+
     /// Returns `true` if `needle` is a prefix of the slice.
     ///
     /// # Examples

From 6751769cce9047ba5b1d920f195bae5c4730ff25 Mon Sep 17 00:00:00 2001
From: Alexis Bourget <alexis.bourget@gmail.com>
Date: Sun, 5 Jul 2020 00:01:47 +0200
Subject: [PATCH 2/3] Fix the bound on U and the feature in the doc test

---
 library/core/src/slice/mod.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 09591aa3ff119..1a66d98988dec 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -1412,6 +1412,7 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
+    /// # #![feature(contains_ref)]
     /// let v = [String::from("Hello"), String::from("world")];
     /// assert!(v.contains_ref("Hello"));
     /// assert!(!v.contains_ref("Rust"));
@@ -1420,6 +1421,7 @@ impl<T> [T] {
     pub fn contains_ref<U>(&self, x: &U) -> bool
     where
         T: PartialEq<U>,
+        U: ?Sized,
     {
         self.iter().any(|e| e == x)
     }

From 69637c331bf177c01b9b2333fce43363c14fe983 Mon Sep 17 00:00:00 2001
From: Alexis Bourget <alexis.bourget@gmail.com>
Date: Sat, 5 Sep 2020 13:54:59 +0200
Subject: [PATCH 3/3] Expose feature gate in example

---
 library/core/src/slice/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 1a66d98988dec..a5baf542f017f 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -1412,7 +1412,7 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(contains_ref)]
+    /// #![feature(contains_ref)]
     /// let v = [String::from("Hello"), String::from("world")];
     /// assert!(v.contains_ref("Hello"));
     /// assert!(!v.contains_ref("Rust"));