ABIGen not generating function pointers for Go

[jmc265]

System information

OS & Version: OSX
Commit hash : e916f97

Expected behaviour

ABIGen will generate a function pointer arg for the generated Go.

Actual behaviour

The generated Go file is not syntactically correct for the function argument.

Steps to reproduce the behaviour

1. Take this contract: https://ethfiddle.com/a7bXVPT940
2. Compile it abigen -sol tmp.sol -pkg foo -out f.go
3. Get errors of the form ./f.go:179:99: undefined: function
4. Observe incorrect Go sytax in f.go:

func (_FunctionPointerTest *FunctionPointerTestTransactor) Test(opts *bind.TransactOpts, callback function) (*types.Transaction, error) {
        return _FunctionPointerTest.contract.Transact(opts, "test", callback)
}

[karalabe]

A function is not a documented ABI parameter type https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI. I'm not sure when this got added into Solidity, or why it supports generating ABIs with it included. I don't think this is a feature that should be supported by the compiler.

[karalabe]

Ping @chriseth @axic

[chriseth]

I think this was added in 0.4.5 (2016-11-21). It is documented here: https://solidity.readthedocs.io/en/develop/abi-spec.html#types

Note that Solidity does not claim to implement the ABI, but it has some types that might be missing from other languages, so users of the abi json should be prepared to encounter unknown types from time to time. I know that this is not a good standardization mechanism, but I think EIPs were not yet in place at that time.

[chriseth]

Hm wait a second, the wiki page you link actually also lists function...

[kegsay]

Presumably abigen can just replace the function type with [24]byte in Go? That would at least mean that projects which use this type can actually compile successfully.

[gballet]

Fixed by #19755