Migration to 0.11: errors of shared functions accross contracts

[maurolacy]

Facing the following error migrating errors to the new format (i.e. to 0.11):

53 | |         HandleMsg::Freeze {} => handle_freeze(deps, env),
   | |                                 ^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `error::ContractError`, found enum `cw1_whitelist::error::ContractError`

This is because handle_freeze() is being imported from cw1-whitelist, which has its own ContractError.

Opening this issue so we can document / discuss solutions to this.

[webmaster128]

Here is an example of mixed type implementations: https://github.com/CosmWasm/cosmwasm/blob/v0.11.0-alpha3/contracts/staking/src/contract.rs#L56-L69

You use ? like

HandleMsg::Freeze {} => Ok(handle_freeze(deps, env)?)

to convert Result<Data, External> to Result<Data, Internal>. For this to work you need an error converter: impl From<External> for Internal.

[maurolacy]

Thanks for the quick response! I'll try this and report back.

[maurolacy]

This works, thanks.

[webmaster128]

Still figuring out the best way to map one error into the other, but code now compiles.

At least for StdError -> custom error we now recommend the thiserror crate with something like

use cosmwasm_std::{CanonicalAddr, StdError};
use thiserror::Error;

// thiserror implements Display and ToString if you
// set the `#[error("…")]` attribute for all cases
#[derive(Error, Debug)]
pub enum MyCustomError {
    #[error("{0}")]
    // let thiserror implement From<StdError> for you
    Std(#[from] StdError),
    // this is whatever we want
    #[error("Permission denied: the sender is not the current owner")]
    NotCurrentOwner {
        expected: CanonicalAddr,
        actual: CanonicalAddr,
    },
    #[error("Messages empty. Must reflect at least one message")]
    MessagesEmpty,
}

However, I don't know how this will look like if you need multiple of those container cases.