IBC TransferMsg: add memo field

[alpe]

Add memo field to IBCMsg.TransferMsg . See blog

[webmaster128]

Nice. This is API breaking but can be added easily in 2.0.0.

[assafmo]

It is API breaking for cosmwasm-std, and requires ibc-go v3.4 or v4.2 for wasmd (with cosmos-sdk v0.45), but can be done in a way such that existing contracts don't break (the field is optional).

Maybe with some Rust/Serde magic the field can be set to an empty string in cosmwasm-std if not provided in the struct?

[webmaster128]

Maybe with some Rust/Serde magic the field can be set to an empty string in cosmwasm-std if not provided in the struct?

The act of adding a field to Rust is the source code breaking part. But this is what CosmWasm 2.0 will be. Source code breaking but not breaking existing contracts.

[assafmo]

Oh I see, then it's a way less dramatic 2.0 than I thought

[webmaster128]

Yeah, nothing is really communicated yet. Alpha leak here.

[webmaster128]

But if you want more of those things, let us know. I'm piling them up here: https://github.com/CosmWasm/cosmwasm/milestone/27

[dzmitry-lahoda]

so addin optional field into json breaks things apart? bad

[dzmitry-lahoda]

if somebody wants memo, use https://github.com/osmosis-labs/osmosis/blob/2e06b7ba485e73a36168ff5e47d63e8f249c9f7e/cosmwasm/contracts/outpost/src/execute.rs#L67 . I port it to our chain too.

[assafmo]

so addin optional field into json breaks things apart? bad

It does not break anything, we've added it on Secret and it works just fine with or without it.

[assafmo]

scrtlabs#19 + scrtlabs/SecretNetwork@101f4f7

[assafmo]

The act of adding a field to Rust is the source code breaking part.

IMO a better way to define breakage is if v1 contracts won't work on CosmWasm v2 chain. If that's the case BTW, you'll have to find a way to migrate all old contracts to v2.

[dzmitry-lahoda]

Memo is essential btw. ICF IBC hooks are still bad. Why? They requre 2x blocks to transfer + act. Imagine the MEV/sandwith/slippage of this? The only DeFi option to use IBC is with memo (when memo carries batch id or execution). We need memo in std :)

[webmaster128]

Memo is essential btw.

Yeah. #1878 fixed this in 2.0. In the meantime you can use CosmosMsg::Stargate to create a bank send with a memo (using prost or anybuf)

so addin optional field into json breaks things apart? bad

Nope. Adding a field to an enum case is a source code breaking change for users of cosmwasm_std.