From 55d74a5fa1ae0431f7b8b0e556d33c48823966fe Mon Sep 17 00:00:00 2001
From: John Nunley <dev@notgull.net>
Date: Sat, 24 Feb 2024 20:06:22 -0800
Subject: [PATCH] feat: Mark StackSlot as Sync

Since it has no interior mutability it should be safe to share between
threads.

Signed-off-by: John Nunley <dev@notgull.net>
---
 src/lib.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index d0af19f..645f0b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -84,6 +84,7 @@ mod sys;
 
 mod notify;
 
+#[cfg(not(feature = "std"))]
 use alloc::boxed::Box;
 
 use core::borrow::Borrow;
@@ -1365,6 +1366,9 @@ fn __test_send_and_sync() {
     fn _assert_sync<T: Sync>() {}
 
     _assert_send::<crate::__private::StackSlot<'_, ()>>();
+    _assert_sync::<crate::__private::StackSlot<'_, ()>>();
+    _assert_send::<crate::__private::StackListener<'_, '_, ()>>();
+    _assert_sync::<crate::__private::StackListener<'_, '_, ()>>();
     _assert_send::<Event<()>>();
     _assert_sync::<Event<()>>();
     _assert_send::<EventListener<()>>();
@@ -1410,6 +1414,7 @@ pub mod __private {
     impl<T> core::panic::UnwindSafe for StackSlot<'_, T> {}
     impl<T> core::panic::RefUnwindSafe for StackSlot<'_, T> {}
     unsafe impl<T> Send for StackSlot<'_, T> {}
+    unsafe impl<T> Sync for StackSlot<'_, T> {}
 
     impl<'ev, T> StackSlot<'ev, T> {
         /// Create a new `StackSlot` on the stack.