Function call_migrate_with_info_raw 

pub fn call_migrate_with_info_raw<A, S, Q>(
    instance: &mut Instance<A, S, Q>,
    env: &[u8],
    msg: &[u8],
    migrate_info: &[u8],
) -> VmResult<Vec<u8>>
where
    A: BackendApi + 'static,
    S: Storage + 'static,
    Q: Querier + 'static,

Calls Wasm export “migrate” and returns raw data from the contract. The result is length limited to prevent abuse but otherwise unchecked. The difference between this function and call_migrate_raw is the additional argument - migrate_info. It contains additional data related to the contract’s migration procedure.

It is safe to call this method instead of call_migrate_raw even if a contract contains the migrate entrypoint without migrate_info. In such case this structure is omitted.