Function vkCreateXcbSurfaceKHR 

pub unsafe extern "system" fn vkCreateXcbSurfaceKHR(
    instance: VkInstance,
    pCreateInfo: *const VkXcbSurfaceCreateInfoKHR,
    pAllocator: *const VkAllocationCallbacks,
    pSurface: *mut VkSurfaceKHR,
) -> VkResult

Available if built with prototypes.