Function vkGetRayTracingShaderGroupHandlesNV 

pub unsafe extern "system" fn vkGetRayTracingShaderGroupHandlesNV(
    device: VkDevice,
    pipeline: VkPipeline,
    firstGroup: u32,
    groupCount: u32,
    dataSize: usize,
    pData: *mut c_void,
) -> VkResult

Available if built with prototypes.