From fd4d2e62cdaebddaeb8c2072676e25b34eecb82d Mon Sep 17 00:00:00 2001
From: Orson Peters <orsonpeters@gmail.com>
Date: Sat, 20 Jun 2026 21:03:37 +0200
Subject: [PATCH] Guarantee 8 bytes of alignment of RawWakerVTable

---
 library/core/src/task/wake.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs
index 473b185d24652..1dbd11426e57e 100644
--- a/library/core/src/task/wake.rs
+++ b/library/core/src/task/wake.rs
@@ -90,6 +90,8 @@ impl RawWaker {
 /// pointers to *different* functions can compare equal (since identical functions can be
 /// deduplicated within a codegen unit).
 ///
+/// This struct is guaranteed to be aligned to at least 8 bytes.
+///
 /// # Thread safety
 /// If the [`RawWaker`] will be used to construct a [`Waker`] then
 /// these functions must all be thread-safe (even though [`RawWaker`] is
@@ -106,6 +108,8 @@ impl RawWaker {
 #[stable(feature = "futures_api", since = "1.36.0")]
 #[allow(unpredictable_function_pointer_comparisons)]
 #[derive(PartialEq, Copy, Clone, Debug)]
+// For bit-stuffing pointers we guarantee align >= 8.
+#[repr(align(8))]
 pub struct RawWakerVTable {
     /// This function will be called when the [`RawWaker`] gets cloned, e.g. when
     /// the [`Waker`] in which the [`RawWaker`] is stored gets cloned.