From d1a9314c28ddc946acbb2ac7907a909b84a0531a Mon Sep 17 00:00:00 2001
From: marc0246 <40955683+marc0246@users.noreply.github.com>
Date: Wed, 16 Oct 2024 19:50:54 +0200
Subject: [PATCH] Fix UB in `impl VertexBufferCollection for Vec<Subbuffer<T>>`
 (#2577)

---
 vulkano/src/pipeline/graphics/vertex_input/collection.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/vulkano/src/pipeline/graphics/vertex_input/collection.rs b/vulkano/src/pipeline/graphics/vertex_input/collection.rs
index b5354b66..442af664 100644
--- a/vulkano/src/pipeline/graphics/vertex_input/collection.rs
+++ b/vulkano/src/pipeline/graphics/vertex_input/collection.rs
@@ -1,5 +1,5 @@
 use crate::buffer::Subbuffer;
-use std::mem;
+use std::mem::{self, ManuallyDrop};
 
 /// A collection of vertex buffers.
 pub trait VertexBuffersCollection {
@@ -32,8 +32,13 @@ impl<T: ?Sized> VertexBuffersCollection for Vec<Subbuffer<T>> {
             mem::align_of::<Subbuffer<[u8]>>(),
         );
 
+        let mut this = ManuallyDrop::new(self);
+        let cap = this.capacity();
+        let len = this.len();
+        let ptr = this.as_mut_ptr();
+
         // SAFETY: All `Subbuffer`s share the same layout.
-        unsafe { mem::transmute::<Vec<Subbuffer<T>>, Vec<Subbuffer<[u8]>>>(self) }
+        unsafe { Vec::from_raw_parts(ptr.cast(), len, cap) }
     }
 }