Function cmd_copy_buffer 

pub unsafe fn cmd_copy_buffer(
    device: &Device,
    command_buffer: CommandBuffer,
    src_buffer: Buffer,
    dst_buffer: Buffer,
    regions: &[BufferCopy],
) -> Result<(), CallError>

Call vkCmdCopyBuffer using this context’s cached function pointer.

Errors

Reports a missing command, invalid slice lengths/counts or a native error.

Safety

The context and all handles must be live and belong to the same Vulkan implementation/device. Meet vkCmdCopyBuffer valid usage, enabled API/extension/feature, pointer-chain lifetime, callback compatibility and host/GPU synchronization requirements. Native resources require explicit destruction after completion.

Khronos reference: vkCmdCopyBuffer