From 640f6f07494ece4ebe7e4d9680fff9a83ab4b0d2 Mon Sep 17 00:00:00 2001
From: Taylor Cramer <cramertj@google.com>
Date: Tue, 22 May 2018 17:10:14 -0700
Subject: [PATCH] Add Pinned type for opting out of Unpin on stable

---
 src/libcore/marker.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index d4a87b13f04d..77db165bcbde 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -607,6 +607,16 @@ unsafe impl<'a, T: ?Sized> Freeze for &'a mut T {}
 #[unstable(feature = "pin", issue = "49150")]
 pub auto trait Unpin {}
 
+/// A type which does not implement `Unpin`.
+///
+/// If a type contains a `Pinned`, it will not implement `Unpin` by default.
+#[unstable(feature = "pin", issue = "49150")]
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub struct Pinned;
+
+#[unstable(feature = "pin", issue = "49150")]
+impl !Unpin for Pinned {}
+
 /// Implementations of `Copy` for primitive types.
 ///
 /// Implementations that cannot be described in Rust