abi/abigen: incorrect handling of overloaded params in struct

[MariusVanDerWijden]

Running abigen on the following contract blows up:

contract Overloader {
    struct F { uint _f; uint __f; uint f; }
    function f(F memory f) public {}
}

Error:

panic: reflect.StructOf: duplicate field F

goroutine 1 [running]:
reflect.StructOf(0xc0000b4820, 0x3, 0x4, 0x0, 0x0)
        /usr/lib/go/src/reflect/type.go:2541 +0x3067
github.com/ethereum/go-ethereum/accounts/abi.NewType(0xc00064fc70, 0x5, 0xc00048afe0, 0x13, 0xc0000d9b80, 0x3, 0x4, 0x0, 0x19, 0x0, ...)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/accounts/abi/type.go:203 +0x13b7
github.com/ethereum/go-ethereum/accounts/abi.(*Argument).UnmarshalJSON(0xc0002bdb80, 0xc0005a260c, 0xf7, 0x1f4, 0x7fc79199c188, 0xc0002bdb80)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/accounts/abi/argument.go:52 +0x16c
encoding/json.(*decodeState).object(0xc00026f550, 0xc3c300, 0xc0002bdb80, 0x199, 0xcd7184, 0xb)
        /usr/lib/go/src/encoding/json/decode.go:626 +0x2082
encoding/json.(*decodeState).value(0xc00026f550, 0xc3c300, 0xc0002bdb80, 0x199, 0xc3c300, 0xc0002bdb80)
        /usr/lib/go/src/encoding/json/decode.go:387 +0x6d
encoding/json.(*decodeState).array(0xc00026f550, 0xb97900, 0xc0000b46a0, 0x197, 0xc00026f578, 0x5b)
        /usr/lib/go/src/encoding/json/decode.go:575 +0x1a7
encoding/json.(*decodeState).value(0xc00026f550, 0xb97900, 0xc0000b46a0, 0x197, 0x1, 0xc000486dc0)
        /usr/lib/go/src/encoding/json/decode.go:377 +0xfd
encoding/json.(*decodeState).object(0xc00026f550, 0xc82fe0, 0xc0000b4680, 0x199, 0xcd7184, 0xb)
        /usr/lib/go/src/encoding/json/decode.go:782 +0x12e5
encoding/json.(*decodeState).value(0xc00026f550, 0xc82fe0, 0xc0000b4680, 0x199, 0xc82fe0, 0xc0000b4680)
        /usr/lib/go/src/encoding/json/decode.go:387 +0x6d
encoding/json.(*decodeState).array(0xc00026f550, 0xb7eb20, 0xc00000e180, 0x16, 0xc00026f578, 0xc000256c5b)
        /usr/lib/go/src/encoding/json/decode.go:575 +0x1a7
encoding/json.(*decodeState).value(0xc00026f550, 0xb7eb20, 0xc00000e180, 0x16, 0xc00063d790, 0x53b031)
        /usr/lib/go/src/encoding/json/decode.go:377 +0xfd
encoding/json.(*decodeState).unmarshal(0xc00026f550, 0xb7eb20, 0xc00000e180, 0xc00026f578, 0x0)
        /usr/lib/go/src/encoding/json/decode.go:180 +0x1f0
encoding/json.Unmarshal(0xc0005a2600, 0x14f, 0x200, 0xb7eb20, 0xc00000e180, 0xc00064f960, 0xc00063d890)
        /usr/lib/go/src/encoding/json/decode.go:107 +0x112
github.com/ethereum/go-ethereum/accounts/abi.(*ABI).UnmarshalJSON(0xc0000f9b00, 0xc0005a2600, 0x14f, 0x200, 0x7fc79199c168, 0xc0000f9b00)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/accounts/abi/abi.go:135 +0x8b
encoding/json.(*decodeState).array(0xc00025cb28, 0xc73760, 0xc0000f9b00, 0x16, 0xc00025cb50, 0x5b)
        /usr/lib/go/src/encoding/json/decode.go:520 +0xc10
encoding/json.(*decodeState).value(0xc00025cb28, 0xc73760, 0xc0000f9b00, 0x16, 0xc00063df60, 0x53ef1e)
        /usr/lib/go/src/encoding/json/decode.go:377 +0xfd
encoding/json.(*decodeState).unmarshal(0xc00025cb28, 0xc73760, 0xc0000f9b00, 0x0, 0x1)
        /usr/lib/go/src/encoding/json/decode.go:180 +0x1f0
encoding/json.(*Decoder).Decode(0xc00025cb00, 0xc73760, 0xc0000f9b00, 0x20, 0xc45000)
        /usr/lib/go/src/encoding/json/stream.go:73 +0x166
github.com/ethereum/go-ethereum/accounts/abi.JSON(0xe25da0, 0xc00000e060, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/accounts/abi/abi.go:50 +0xb7
github.com/ethereum/go-ethereum/accounts/abi/bind.Bind(0xc000495400, 0x8, 0x8, 0xc000495300, 0x8, 0x8, 0xc000495380, 0x8, 0x8, 0xc00048e380, ...)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/accounts/abi/bind/bind.go:63 +0x1e11
main.abigen(0xc0000fbb80, 0x0, 0x0)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/cmd/abigen/main.go:256 +0x8ef
github.com/ethereum/go-ethereum/cmd/utils.MigrateFlags.func1(0xc0000fbb80, 0xc0000fbb80, 0xc00035fbe7)
        /home/matematik/go/src/github.com/ethereum/go-ethereum/cmd/utils/flags.go:1823 +0xbe
gopkg.in/urfave/cli%2ev1.HandleAction(0xbbb620, 0xc000430fd0, 0xc0000fbb80, 0xc000548900, 0x0)
        /home/matematik/go/pkg/mod/gopkg.in/urfave/cli.v1@v1.20.0/app.go:490 +0xc8
gopkg.in/urfave/cli%2ev1.(*App).Run(0xc0001e3040, 0xc000032090, 0x9, 0x9, 0x0, 0x0)
        /home/matematik/go/pkg/mod/gopkg.in/urfave/cli.v1@v1.20.0/app.go:264 +0x5dd
main.main()
        /home/matematik/go/src/github.com/ethereum/go-ethereum/cmd/abigen/main.go:274 +0xe6
generate.go:3: running "abigen": exit status 2