Simple struct requires SpreadLayout trait implementation

[h4x3rotab]

Suppose we just want to write a simple contract to store some H160 EVM contract address:

#[derive(Encode, Decode, Debug, PackedLayout, SpreadLayout)]
struct Config {
  evm_contract: H160,
}

#[ink(storage)]
struct MyContract {
  config: Config,
}

The compiler will complain that primitive_types::H160 doesn't implement SpreadLayout. So it cannot derive PackedLayout for struct Config.

It would be nice if any data type implements Encode + Decode can be stored in the storage by packing as a bytes blob by default. In this case, H160 is defined outside in the crate primitive_types. I cannot easily implement a trait for that, unless I create a wrapper type and write the boilerplate code.

Tested with ink v3.3.1

[HCastano]

Hey, sorry for the late response here. As part of ink! 4.0 we've removed SpreadLayout, PackedLayout, et. al (see #1331). I'm gonna close this since you should be able to do this without any problems with ink! 4.0. If you can't feel free to re-open it.