From 771aa30bbe46e43dbeff855fe4090c1510d48a60 Mon Sep 17 00:00:00 2001
From: marc0246 <40955683+marc0246@users.noreply.github.com>
Date: Wed, 13 Sep 2023 09:30:12 +0200
Subject: [PATCH] Fix Miri warnings when running the suballocator tests (#2330)

---
 vulkano/src/memory/allocator/mod.rs          | 19 +++++++++++++++++++
 vulkano/src/memory/allocator/suballocator.rs |  8 ++++----
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/vulkano/src/memory/allocator/mod.rs b/vulkano/src/memory/allocator/mod.rs
index a1bca1e127..24dc4cc7a4 100644
--- a/vulkano/src/memory/allocator/mod.rs
+++ b/vulkano/src/memory/allocator/mod.rs
@@ -243,6 +243,7 @@ use parking_lot::Mutex;
 use std::{
     error::Error,
     fmt::{Debug, Display, Error as FmtError, Formatter},
+    mem,
     ops::BitOr,
     ptr,
     sync::Arc,
@@ -728,6 +729,24 @@ pub struct AllocationHandle(pub *mut ());
 unsafe impl Send for AllocationHandle {}
 unsafe impl Sync for AllocationHandle {}
 
+impl AllocationHandle {
+    /// Stores a index inside an `AllocationHandle`.
+    #[allow(clippy::useless_transmute)]
+    #[inline]
+    pub const fn from_index(index: usize) -> Self {
+        // SAFETY: `usize` and `*mut ()` have the same layout.
+        AllocationHandle(unsafe { mem::transmute::<usize, *mut ()>(index) })
+    }
+
+    /// Retrieves a previously-stored index from the `AllocationHandle`.
+    #[allow(clippy::transmutes_expressible_as_ptr_casts)]
+    #[inline]
+    pub const fn into_index(self) -> usize {
+        // SAFETY: `usize` and `*mut ()` have the same layout.
+        unsafe { mem::transmute::<*mut (), usize>(self.0) }
+    }
+}
+
 /// Error that can be returned when creating an [allocation] using a [memory allocator].
 ///
 /// [allocation]: MemoryAlloc
diff --git a/vulkano/src/memory/allocator/suballocator.rs b/vulkano/src/memory/allocator/suballocator.rs
index 05aca577c8..2a3122b20f 100644
--- a/vulkano/src/memory/allocator/suballocator.rs
+++ b/vulkano/src/memory/allocator/suballocator.rs
@@ -409,7 +409,7 @@ unsafe impl Suballocator for FreeListAllocator {
                                 offset,
                                 size,
                                 allocation_type,
-                                handle: AllocationHandle(id.get() as _),
+                                handle: AllocationHandle::from_index(id.get()),
                             });
                         }
                     }
@@ -431,7 +431,7 @@ unsafe impl Suballocator for FreeListAllocator {
     unsafe fn deallocate(&self, suballocation: Suballocation) {
         // SAFETY: The caller must guarantee that `suballocation` refers to a currently allocated
         // allocation of `self`.
-        let node_id = SlotId::new(suballocation.handle.0 as _);
+        let node_id = SlotId::new(suballocation.handle.into_index());
 
         let state = unsafe { &mut *self.state.get() };
         let node = state.nodes.get_mut(node_id);
@@ -891,7 +891,7 @@ unsafe impl Suballocator for BuddyAllocator {
                         offset,
                         size: layout.size(),
                         allocation_type,
-                        handle: AllocationHandle(min_order as _),
+                        handle: AllocationHandle::from_index(min_order),
                     });
                 }
             }
@@ -908,7 +908,7 @@ unsafe impl Suballocator for BuddyAllocator {
     #[inline]
     unsafe fn deallocate(&self, suballocation: Suballocation) {
         let mut offset = suballocation.offset;
-        let order = suballocation.handle.0 as usize;
+        let order = suballocation.handle.into_index();
 
         let min_order = order;
         let state = unsafe { &mut *self.state.get() };