From 4e7d4c7778a00371ba707fb8f9022bcbb443bb29 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 27 Feb 2019 15:32:32 +0100
Subject: [PATCH 1/3] ManuallyDrop != MaybeUninit

---
 src/libcore/mem.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index f41d293e80a..6b1b91d00fa 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -900,10 +900,16 @@ pub fn discriminant<T>(v: &T) -> Discriminant<T> {
     }
 }
 
+// FIXME: Reference `MaybeUninit` from these docs, once that is stable.
 /// A wrapper to inhibit compiler from automatically calling `T`’s destructor.
 ///
 /// This wrapper is 0-cost.
 ///
+/// `ManuallyDrop<T>` is subject to the same layout optimizations as `T`.
+/// As a consequence, it has *no effect* on the assumptions that the compiler makes
+/// about all values being initialized at their type.  In particular, initializing
+/// a `ManuallyDrop<&T>` with [`mem::zeroed`] is undefined behavior.
+///
 /// # Examples
 ///
 /// This wrapper helps with explicitly documenting the drop order dependencies between fields of
@@ -935,6 +941,8 @@ pub fn discriminant<T>(v: &T) -> Discriminant<T> {
 ///     }
 /// }
 /// ```
+///
+/// [`mem::zeroed']: fn.zeroed.html
 #[stable(feature = "manually_drop", since = "1.20.0")]
 #[lang = "manually_drop"]
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]

From f92c20426ea5f5ddcc6dcf73dbe0739d3d76b614 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 27 Feb 2019 18:58:19 +0100
Subject: [PATCH 2/3] improve readability

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

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 6b1b91d00fa..f78213ba9f6 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -908,7 +908,7 @@ pub fn discriminant<T>(v: &T) -> Discriminant<T> {
 /// `ManuallyDrop<T>` is subject to the same layout optimizations as `T`.
 /// As a consequence, it has *no effect* on the assumptions that the compiler makes
 /// about all values being initialized at their type.  In particular, initializing
-/// a `ManuallyDrop<&T>` with [`mem::zeroed`] is undefined behavior.
+/// a `ManuallyDrop<&mut T>` with [`mem::zeroed`] is undefined behavior.
 ///
 /// # Examples
 ///

From 0c1a38ce3b281ce23b9ba84312f58ba6ac82af57 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Thu, 28 Feb 2019 09:24:35 +0100
Subject: [PATCH 3/3] Update src/libcore/mem.rs

Co-Authored-By: RalfJung <post@ralfj.de>
---
 src/libcore/mem.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index f78213ba9f6..94f342e7e8e 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -942,7 +942,7 @@ pub fn discriminant<T>(v: &T) -> Discriminant<T> {
 /// }
 /// ```
 ///
-/// [`mem::zeroed']: fn.zeroed.html
+/// [`mem::zeroed`]: fn.zeroed.html
 #[stable(feature = "manually_drop", since = "1.20.0")]
 #[lang = "manually_drop"]
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]