Revert reason about multicall

[mds1]

Yep that is correct, custom errors can be decoded basically the same way calldata can be decoded—you know the signature to get the 4 byte selector, and with the signature you know how to decode the rest of the args

[mds1]

It is possible! If the call fails, the Result.returnData (or just returnData depending on which method) contains the ABI encoded failure reason.

If that reason is an Error(string) from a require, you can decode it like this: https://github.com/Uniswap/v3-periphery/blob/6cce88e63e176af1ddb6cc56e029110289622317/contracts/base/Multicall.sol#L16-L23

If it's a panic you can ABI decode the Panic(uint256) and map it to an error code. More info here: https://docs.soliditylang.org/en/latest/control-structures.html#error-handling-assert-require-revert-and-exceptions

[gigamesh]

Awesome thank you - are custom errors surfaced in returnData as well, or only require() error strings & panic codes?

EDIT: I was just informed that if its a custom error, I can decode the first 4 bytes (error function selector) of returnData but I'll need to know the signature to decode it. That should work for what I'm trying to do but lmk if it doesn't sound right.