Merge #963

963: Add repr(C) on mapping structs r=trivial a=kvark

**Connections**
Required for https://phabricator.services.mozilla.com/D92636

**Description**
Allows C clients to avoid redefining those structs.

**Testing**
No need

Co-authored-by: Dzmitry Malyshau <dmalyshau@mozilla.com>

wgpu-core/src/device/mod.rs

@@ -70,6 +70,7 @@ pub fn all_image_stages() -> hal::pso::PipelineStage {
         | Ps::TRANSFER
 }
 
+#[repr(C)]
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[cfg_attr(feature = "trace", derive(serde::Serialize))]
 #[cfg_attr(feature = "replay", derive(serde::Deserialize))]

wgpu-core/src/resource.rs

@@ -104,6 +104,7 @@ unsafe impl<B: hal::Backend> Sync for BufferMapState<B> {}
 
 pub type BufferMapCallback = unsafe extern "C" fn(status: BufferMapAsyncStatus, userdata: *mut u8);
 
+#[repr(C)]
 #[derive(Debug)]
 pub struct BufferMapOperation {
     pub host: crate::device::HostMap,