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abigen and the geth library can't work together with bytes32[] <=> [][32]byte #15212

coreyog opened this Issue Sep 27, 2017 · 0 comments


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coreyog commented Sep 27, 2017

System information

Geth version: 1.7.0-stable
OS & Version: Linux Mint 18.2 x64
Commit hash : N/A
Go Version: go version go1.9 linux/amd64

Expected behaviour

When I run the latest version of abigen on a contract I expect the output go code to work with the latest version of go-ethereum. My contract uses bytes32 as the type for IDs of objects. In one struct I have a list of IDs and use bytes32[] to hold that list. Abigen properly outputs it to the go type [][32]byte. I expect that when I use the generated code to call my contract, that the proper types are returned from the call without error.

Actual behaviour

When I call in to the generated code, I receive an error stating abi: cannot unmarshal [][]uint8 in to [][32]uint8. If I modify the generated go code so that it's just [][]byte instead of [][32]byte then the function call works as expected.

Steps to reproduce the behaviour

Contract Test.sol:

pragma solidity ^0.4.15;

contract Test {
  function testDynamicFixedBytes() constant returns (bytes32[]) {
    var array = new bytes32[](2);
    array[0] = "0x1234567890";
    array[1] = "0x0987654321";
    return array;

Run abigen -pkg main -sol Test.sol -out Test.go


package main

import (


func main() {
	contract := "b1815f478391d8fb7a22af0c9a1a5523a16e2429"
	ethURL := "/home/corey/eth/data/geth.ipc"
	fromAddress := "fcf5e6a6ce24cdeef66697a41ba75b039c17d2cb"
	contractAddress := common.HexToAddress(contract)
	client, err := ethclient.Dial(ethURL)
	if err != nil {
	test, err := NewTest(contractAddress, client)
	if err != nil {

	opts := bind.CallOpts{
		Context: context.Background(),
		From:    common.HexToAddress(fromAddress),
	array, err := test.TestDynamicFixedBytes(&opts)
	if err != nil {
	for _, v := range array {


panic: abi: cannot unmarshal [][]uint8 in to [][32]uint8

goroutine 1 [running]:
        /home/corey/src/goprojects/src/playground/main.go:33 +0x32d

The line that's generating the error is in go-ethereum/accounts/abi/reflect.go at line 90.

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