From 3fff2d95bf90514e66892ca9be666c35eeae9165 Mon Sep 17 00:00:00 2001
From: Ulrik Sverdrup <bluss@users.noreply.github.com>
Date: Sat, 7 Oct 2017 21:33:36 +0200
Subject: core: Ensure std::mem::Discriminant is Send + Sync

`PhantomData<*const T>` has the implication of Send / Syncness following
the *const T type, but the discriminant should always be Send and Sync.

Use `PhantomData<fn() -> T>` which has the same variance in T, but is Send + Sync
---
 src/libcore/tests/mem.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

(limited to 'src/libcore/tests')

diff --git a/src/libcore/tests/mem.rs b/src/libcore/tests/mem.rs
index 86e59c736ba..f55a1c81463 100644
--- a/src/libcore/tests/mem.rs
+++ b/src/libcore/tests/mem.rs
@@ -121,3 +121,19 @@ fn test_transmute() {
     }
 }
 
+#[test]
+#[allow(dead_code)]
+fn test_discriminant_send_sync() {
+    enum Regular {
+        A,
+        B(i32)
+    }
+    enum NotSendSync {
+        A(*const i32)
+    }
+
+    fn is_send_sync<T: Send + Sync>() { }
+
+    is_send_sync::<Discriminant<Regular>>();
+    is_send_sync::<Discriminant<NotSendSync>>();
+}
-- 
cgit 1.4.1-3-g733a5