Public / Internal modifier spawns error: This type is only supported in the new experimental ABI encoder [duplicate]

Question

I have this code snippet:

pragma solidity >=0.5.0 <0.7.0;

import "@aztec/protocol/contracts/libs/NoteUtils.sol";

library EscrowUtils {
    using NoteUtils for bytes;

    struct Note {
        address owner;
        bytes32 noteHash;
    }

    function noteBytesToStruct(bytes memory note)
        internal
        pure
        returns (Note memory codedNote)
    {
        (address owner, bytes32 noteHash, ) = note.extractNote();
        return Note(owner, noteHash);
    }
}

which does not throw any errors. However, when I change the visibility modifier on the function to public, I get:

This type is only supported in the new experimental ABI encoder. Use "pragma experimental ABIEncoderV2;" to enable the feature.

Why changing modifier causes this error?

Answer 1

Because calling a function which returns a struct is currently not supported:

• From another contract instance
• From an off-chain script or app

Change returns (Note memory codedNote) and return Note(owner, noteHash),

To returns (address, bytes32) and return (owner, noteHash).