fix: Move DropGuards to the end of their parent structs. (#8353)

Author: jerzywilczek

CHANGELOG.md

@@ -93,6 +93,10 @@ SamplerDescriptor {
 
 - Align copies b/w textures and buffers via a single intermediate buffer per copy when `D3D12_FEATURE_DATA_D3D12_OPTIONS13.UnrestrictedBufferTextureCopyPitchSupported` is `false`. By @ErichDonGubler in [#7721](https://github.com/gfx-rs/wgpu/pull/7721).
 
+#### hal
+
+- `DropCallback`s are now called after dropping all other fields of their parent structs. By @jerzywilczek in [#8353](https://github.com/gfx-rs/wgpu/pull/8353)
+
 ## v27.0.2 (2025-10-03)
 
 ### Bug Fixes

wgpu-hal/src/gles/mod.rs

@@ -408,13 +408,16 @@ impl TextureInner {
 #[derive(Debug)]
 pub struct Texture {
     pub inner: TextureInner,
-    pub drop_guard: Option<crate::DropGuard>,
     pub mip_level_count: u32,
     pub array_layer_count: u32,
     pub format: wgt::TextureFormat,
     #[allow(unused)]
     pub format_desc: TextureFormatDesc,
     pub copy_size: CopyExtent,
+
+    // The `drop_guard` field must be the last field of this struct so it is dropped last.
+    // Do not add new fields after it.
+    pub drop_guard: Option<crate::DropGuard>,
 }
 
 impl crate::DynTexture for Texture {}

wgpu-hal/src/vulkan/mod.rs

@@ -156,7 +156,6 @@ pub struct DebugUtilsMessengerUserData {
 pub struct InstanceShared {
     raw: ash::Instance,
     extensions: Vec<&'static CStr>,
-    drop_guard: Option<crate::DropGuard>,
     flags: wgt::InstanceFlags,
     memory_budget_thresholds: wgt::MemoryBudgetThresholds,
     debug_utils: Option<DebugUtils>,
@@ -171,6 +170,10 @@ pub struct InstanceShared {
     /// It is associated with a `VkInstance` and its children,
     /// except for a `VkPhysicalDevice` and its children.
     instance_api_version: u32,
+
+    // The `drop_guard` field must be the last field of this struct so it is dropped last.
+    // Do not add new fields after it.
+    drop_guard: Option<crate::DropGuard>,
 }
 
 pub struct Instance {
@@ -715,7 +718,6 @@ struct DeviceShared {
     family_index: u32,
     queue_index: u32,
     raw_queue: vk::Queue,
-    drop_guard: Option<crate::DropGuard>,
     instance: Arc<InstanceShared>,
     physical_device: vk::PhysicalDevice,
     enabled_extensions: Vec<&'static CStr>,
@@ -737,6 +739,10 @@ struct DeviceShared {
     texture_identity_factory: ResourceIdentityFactory<vk::Image>,
     /// As above, for texture views.
     texture_view_identity_factory: ResourceIdentityFactory<vk::ImageView>,
+
+    // The `drop_guard` field must be the last field of this struct so it is dropped last.
+    // Do not add new fields after it.
+    drop_guard: Option<crate::DropGuard>,
 }
 
 impl Drop for DeviceShared {
@@ -945,12 +951,15 @@ impl crate::DynAccelerationStructure for AccelerationStructure {}
 #[derive(Debug)]
 pub struct Texture {
     raw: vk::Image,
-    drop_guard: Option<crate::DropGuard>,
     external_memory: Option<vk::DeviceMemory>,
     block: Option<gpu_alloc::MemoryBlock<vk::DeviceMemory>>,
     format: wgt::TextureFormat,
     copy_size: crate::CopyExtent,
     identity: ResourceIdentity<vk::Image>,
+
+    // The `drop_guard` field must be the last field of this struct so it is dropped last.
+    // Do not add new fields after it.
+    drop_guard: Option<crate::DropGuard>,
 }
 
 impl crate::DynTexture for Texture {}