From 603553458639cd65f3cc75b9b74f8176af81aa2b Mon Sep 17 00:00:00 2001
From: Kerollmops <renault.cle@gmail.com>
Date: Wed, 4 Jul 2018 21:54:45 +0200
Subject: [PATCH 1/3] Implement `Option::replace` in the core library

---
 src/libcore/option.rs | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index 20bc173f7e154..db0a807d152a4 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -845,6 +845,33 @@ impl<T> Option<T> {
     pub fn take(&mut self) -> Option<T> {
         mem::replace(self, None)
     }
+
+    /// Replaces the actual value in the option by the value given in parameter,
+    /// returning the old value if present,
+    /// leaving a `Some` in its place without deinitializing either one.
+    ///
+    /// [`Some`]: #variant.Some
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(option_replace)]
+    ///
+    /// let mut x = Some(2);
+    /// let old = x.replace(5);
+    /// assert_eq!(x, Some(5));
+    /// assert_eq!(old, Some(2));
+    ///
+    /// let mut x = None;
+    /// let old = x.replace(3);
+    /// assert_eq!(x, Some(3));
+    /// assert_eq!(old, None);
+    /// ```
+    #[inline]
+    #[unstable(feature = "option_replace", issue = "51998")]
+    pub fn replace(&mut self, value: T) -> Option<T> {
+        mem::replace(self, Some(value))
+    }
 }
 
 impl<'a, T: Clone> Option<&'a T> {

From af87a3594a9f852de0eb7fec7a2f2e7c5fdb4fe8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20RENAULT?= <crenault@vente-privee.com>
Date: Mon, 9 Jul 2018 14:50:54 +0200
Subject: [PATCH 2/3] Add a basic test to `Option::replace`

---
 src/libcore/tests/lib.rs    |  1 +
 src/libcore/tests/option.rs | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/libcore/tests/lib.rs b/src/libcore/tests/lib.rs
index 9d4a5213992a1..ca7db6e4639a5 100644
--- a/src/libcore/tests/lib.rs
+++ b/src/libcore/tests/lib.rs
@@ -44,6 +44,7 @@
 #![feature(reverse_bits)]
 #![feature(iterator_find_map)]
 #![feature(slice_internals)]
+#![feature(option_replace)]
 
 extern crate core;
 extern crate test;
diff --git a/src/libcore/tests/option.rs b/src/libcore/tests/option.rs
index 22109e28edd9b..bc3e61a4f541f 100644
--- a/src/libcore/tests/option.rs
+++ b/src/libcore/tests/option.rs
@@ -297,3 +297,18 @@ fn test_try() {
     }
     assert_eq!(try_option_err(), Err(NoneError));
 }
+
+#[test]
+fn test_replace() {
+    let mut x = Some(2);
+    let old = x.replace(5);
+
+    assert_eq!(x, Some(5));
+    assert_eq!(old, Some(2));
+
+    let mut x = None;
+    let old = x.replace(3);
+
+    assert_eq!(x, Some(3));
+    assert_eq!(old, None);
+}

From c8f0e6f210caccdaea7dc59fd970c81018ddfb00 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20RENAULT?= <crenault@vente-privee.com>
Date: Mon, 9 Jul 2018 14:52:32 +0200
Subject: [PATCH 3/3] Fix the documentation of `Option::replace`

---
 src/libcore/option.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index db0a807d152a4..f3e823670aaab 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -848,7 +848,7 @@ impl<T> Option<T> {
 
     /// Replaces the actual value in the option by the value given in parameter,
     /// returning the old value if present,
-    /// leaving a `Some` in its place without deinitializing either one.
+    /// leaving a [`Some`] in its place without deinitializing either one.
     ///
     /// [`Some`]: #variant.Some
     ///