Additional conditional compilation fix

Author: andyleiserson

wgpu-core/src/id.rs

@@ -1,5 +1,4 @@
-use crate::{storage::StorageItem, Epoch, Index};
-use alloc::sync::Arc;
+use crate::{Epoch, Index};
 use core::{
     cmp::Ordering,
     fmt::{self, Debug},
@@ -169,16 +168,16 @@ impl<T: Marker> Hash for PointerId<T> {
 }
 
 #[cfg(feature = "serde")]
-impl<T: StorageItem> From<&Arc<T>> for PointerId<T::Marker> {
-    fn from(arc: &Arc<T>) -> Self {
+impl<T: crate::storage::StorageItem> From<&alloc::sync::Arc<T>> for PointerId<T::Marker> {
+    fn from(arc: &alloc::sync::Arc<T>) -> Self {
         // Since the memory representation of `Arc<T>` is just a pointer to
         // `ArcInner<T>`, it would be nice to use that pointer as the trace ID,
         // since many `into_trace` implementations would then be no-ops at
         // runtime. However, `Arc::as_ptr` returns a pointer to the contained
         // data, not to the `ArcInner`. The `ArcInner` stores the reference
         // counts before the data, so the machine code for this conversion has
         // to add an offset to the pointer.
-        PointerId::PointerId(Arc::as_ptr(arc) as usize, PhantomData)
+        PointerId::PointerId(alloc::sync::Arc::as_ptr(arc) as usize, PhantomData)
     }
 }