GetSignBytes broken for IBC messages

[jackzampolin]

The recent codec changes broke the SubModuleCdcs that are used to GetSignBytes for IBC messages. There is a test that reproduces this issue in #7637

[clevinson]

@jackzampolin can you link to which recent codec changes you're referring to? Lot of pieces moving right now... Would be great if there's a specific PR that you know caused this issue.

[jackzampolin]

The last PR that touched the code that is in 0.40.0-rc0 but not in master is #7086

[aaronc]

IBC doesn't support amino at all so GetSignBytes is meaningless and should be considered basically deprecated.

[aaronc]

Ibc GetSignBytes methods should probably all panic

[jackzampolin]

@aaronc well they do! Maybe I need to migrate to another signing method.

[colin-axner]

I think this is from the relayer feature of bundling relay messages by message size. Is there another way we can determine the bytes of a message easily? If not, I'd propose just removing the feature. We can limit relayed transactions by the number of messages which is sufficient and probably more useful imo

[colin-axner]

I think this fix should work for the relayer.

Maybe we should change the GetSignBytes function in the SDK to explicitly panic? We could probably remove most of the SubModuleCdcs as well, except there is one place we use it in the code for Versions. Is this something that should be changed or might cause an issue?

Edit: We decided internally to change the handling of Versions for other reasons

[colin-axner]

Found some other places we use SubModuleCdc. Is this something we should try to replace by using the application defined codec?

[jackzampolin]

Closing as addressed.