refactor(core): replace TransferError::BufferOverrun::end_offset with transfer's size

Transfer operations are expressed in terms of a start offset and a size.
Trying to store anything else in errors and traces yields extra
complexity and loses clarity. Change `TransferError::BufferOverrun` so
that its `end_offset` field is no more. Instead, add a `size` field that
should only ever be saving off fields already provided by user
operations.

Author: ErichDonGubler

wgpu-core/src/command/transfer.rs

@@ -47,10 +47,12 @@ pub enum TransferError {
     MissingBufferUsage(#[from] MissingBufferUsageError),
     #[error(transparent)]
     MissingTextureUsage(#[from] MissingTextureUsageError),
-    #[error("Copy of {start_offset}..{end_offset} would end up overrunning the bounds of the {side:?} buffer of size {buffer_size}")]
+    #[error(
+        "Copy at offset {start_offset} for {size} bytes would end up overrunning the bounds of the {side:?} buffer of size {buffer_size}"
+    )]
     BufferOverrun {
         start_offset: BufferAddress,
-        end_offset: BufferAddress,
+        size: BufferAddress,
         buffer_size: BufferAddress,
         side: CopySide,
     },
@@ -344,7 +346,7 @@ pub(crate) fn validate_linear_texture_data(
     if bytes_in_copy > buffer_size || offset > buffer_size - bytes_in_copy {
         return Err(TransferError::BufferOverrun {
             start_offset: offset,
-            end_offset: offset.wrapping_add(bytes_in_copy),
+            size: bytes_in_copy,
             buffer_size,
             side: buffer_side,
         });
@@ -1021,7 +1023,7 @@ pub(super) fn copy_buffer_to_buffer(
     if source_end_offset > src_buffer.size {
         return Err(TransferError::BufferOverrun {
             start_offset: source_offset,
-            end_offset: source_end_offset,
+            size,
             buffer_size: src_buffer.size,
             side: CopySide::Source,
         }
@@ -1030,7 +1032,7 @@ pub(super) fn copy_buffer_to_buffer(
     if destination_end_offset > dst_buffer.size {
         return Err(TransferError::BufferOverrun {
             start_offset: destination_offset,
-            end_offset: destination_end_offset,
+            size,
             buffer_size: dst_buffer.size,
             side: CopySide::Destination,
         }

wgpu-core/src/device/queue.rs

@@ -663,7 +663,7 @@ impl Queue {
         if buffer_offset + buffer_size.get() > buffer.size {
             return Err(TransferError::BufferOverrun {
                 start_offset: buffer_offset,
-                end_offset: buffer_offset + buffer_size.get(),
+                size: buffer_size.get(),
                 buffer_size: buffer.size,
                 side: CopySide::Destination,
             });