disasm: Names for Tuple Components are not set

[yohamta]

Problem

When inferring ABIs from bytecode, WhatsABI currently omits names for tuple components that are likely derived from Solidity structs. While the ABI specification technically allows unnamed tuple components, Solidity always generates names for struct members when creating the ABI. This discrepancy causes compatibility issues with libraries like go-ethereum that expect these names to be present when working with structs (See https://github.com/ethereum/go-ethereum/blob/v1.14.11/accounts/abi/type.go#L181).

Example contract:

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

contract TestC {

    struct MyTuple {
        uint256 num;
        string str;
        bool flag;
    }

    function getTuple() external pure returns (MyTuple memory) {
        return MyTuple(123, "hello", true);
    }

    function setTuple(MyTuple calldata inputTuple) external pure returns (uint256, string memory, bool) {
        return (inputTuple.num, inputTuple.str, inputTuple.flag);
    }
}

ABI Generated by Solidity Compiler:

{
  "contracts": {
    "test.sol:TestC": {
      "abi": [
        {
          "inputs": [],
          "name": "getTuple",
          "outputs": [
            {
              "components": [
                {
                  "internalType": "uint256",
                  "name": "num",
                  "type": "uint256"
                },
                {
                  "internalType": "string",
                  "name": "str",
                  "type": "string"
                },
                {
                  "internalType": "bool",
                  "name": "flag",
                  "type": "bool"
                }
              ],
              "internalType": "struct TestC.MyTuple",
              "name": "",
              "type": "tuple"
            }
          ],
          "stateMutability": "pure",
          "type": "function"
        },
        {
          "inputs": [
            {
              "components": [
                {
                  "internalType": "uint256",
                  "name": "num",
                  "type": "uint256"
                },
                {
                  "internalType": "string",
                  "name": "str",
                  "type": "string"
                },
                {
                  "internalType": "bool",
                  "name": "flag",
                  "type": "bool"
                }
              ],
              "internalType": "struct TestC.MyTuple",
              "name": "inputTuple",
              "type": "tuple"
            }
          ],
          "name": "setTuple",
          "outputs": [
            {
              "internalType": "uint256",
              "name": "",
              "type": "uint256"
            },
            {
              "internalType": "string",
              "name": "",
              "type": "string"
            },
            {
              "internalType": "bool",
              "name": "",
              "type": "bool"
            }
          ],
          "stateMutability": "pure",
          "type": "function"
        }
      ]
    }
  },
  "version": "0.8.25+commit.b61c2a91.Darwin.appleclang"
}

Proposed solution

Fill in the component names with _n when they're empty.

Fill in the component names with field${n} when they're empty.

Example:

{
   "type": "function",
   "selector": "0x95d376d7",
   "payable": false,
   "stateMutability": "payable",
   "inputs": [
     {
       "type": "tuple",
       "name": "",
       "components": [
         { "type": "uint32", "name": "" },
         { "type": "bytes", "name": "" },
         { "type": "bytes32", "name": "" },
         { "type": "uint64", "name": "" },
         { "type": "address", "name": "" }
       ]
     },
     { "type": "bytes", "name": "" }
   ],
   "sig": "assignJob((uint32,bytes,bytes32,uint64,address),bytes)",
   "name": "assignJob",
   "constant": false
}

To be:

{
  "type": "function",
  "selector": "0x95d376d7",
  "payable": false,
  "stateMutability": "payable",
  "inputs": [
    {
      "type": "tuple",
      "name": "",
      "components": [
        { "type": "uint32", "name": "field0" },
        { "type": "bytes", "name": "field1" },
        { "type": "bytes32", "name": "field2" },
        { "type": "uint64", "name": "field3" },
        { "type": "address", "name": "field4" }
      ]
    },
    { "type": "bytes", "name": "" }
  ],
  "sig": "assignJob((uint32,bytes,bytes32,uint64,address),bytes)",
  "name": "assignJob",
  "constant": false
}

EDIT: Adjusted the placeholder format that should be supported by geth.

[shazow]

HMMM! That is annoying behaviour on go-ethereum's part!

I'm generally hesitant to add made up results that WhatsABI did not actually extract. It would make it harder to distinguish if the ABI actually has a field named _0 vs the disassembler just assigning it that name.

I guess some options:

1. Add a helper for augmenting any ABI with missing names into something go-ethereum-friendly.
2. Add an optional field to autoload to use helper from (1). Not sure if this should be the default? Technically a breaking change, I guess.
3. Just do it by default and abstract away from the user.

What do you think?

[yohamta]

@shazow I understand your concern; that makes a lot of sense. From a user’s perspective, I think having a Geth-friendly ABI generated by default might be preferable.

[shazow]

@yohamta I'm hesitant to make it default but I'll consider it. Would you be interested in contributing this? Could start with a standalone helper like abiFillEmptyNames that takes an ABI and fills in any empty names, then we can figure out where to insert it for autoload?

[yohamta]

That sounds good to me! I'll open a draft PR later so we can discuss further.

[shazow]

@yohamta Do you have a deployed contract/whatsabi code to reproduce this issue by the way?

[yohamta]

@shazow Yes, here is the contract that reproduces the issue:
https://mantlescan.xyz/address/0x806feB7478b61bf068aA12C9413C6Ad7DD12232a