From b61a4c20c6acd963070adb083b12d5e21a5843d3 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Mon, 7 May 2018 12:11:22 +0200
Subject: [PATCH] make the const constructor unstable

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

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 6d64d91312e0..6836f8622b0e 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -959,6 +959,7 @@ impl<T> ManuallyDrop<T> {
     /// ManuallyDrop::new(Box::new(()));
     /// ```
     #[stable(feature = "manually_drop", since = "1.20.0")]
+    #[rustc_const_unstable(feature = "const_manually_drop_new")]
     #[inline]
     pub const fn new(value: T) -> ManuallyDrop<T> {
         ManuallyDrop { value: value }