From a0ed99e2f0a37fb04f0a1c728e0bc81ba1e7f482 Mon Sep 17 00:00:00 2001
From: Joshua Simmons <josh@nega.tv>
Date: Sun, 20 Nov 2022 00:20:39 +0100
Subject: [PATCH] Add `Upcast` trait for casting to super-trait

---
 narcissus-core/src/lib.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/narcissus-core/src/lib.rs b/narcissus-core/src/lib.rs
index 2c09509..cb63fdd 100644
--- a/narcissus-core/src/lib.rs
+++ b/narcissus-core/src/lib.rs
@@ -264,6 +264,10 @@ pub fn zeroed_box<T>() -> Box<MaybeUninit<T>> {
 /// Negative traits aren't stable yet, so use a dummy PhantomData marker to implement !Send
 pub type PhantomUnsend = std::marker::PhantomData<*mut ()>;
 
+pub trait Upcast<T: ?Sized> {
+    fn upcast(&self) -> &T;
+}
+
 #[must_use]
 pub fn align_offset(x: usize, align: usize) -> usize {
     debug_assert!(align.is_power_of_two());
-- 
2.49.0