go-ethereum/accounts/abi/abigen/source2.go.tpl
Vadim Tertilov 289826fefb
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cmd/abigen/v2: add package-level errors (#34076)
# Summary

Replaces the inline `errors.New("event signature mismatch")` in
generated `UnpackXxxEvent` methods with per-event package-level sentinel
errors (e.g. `ErrTransferSignatureMismatch`,
`ErrApprovalSignatureMismatch`), allowing callers to reliably
distinguish a topic mismatch from a genuine decoding failure via
`errors.Is`.

Each event gets its own sentinel, generated via the abigen template:

```go
var ErrTransferSignatureMismatch = errors.New("event signature mismatch")
```

This scoping is intentional — it allows callers to be precise about
*which* event was mismatched, which is useful when routing logs across
multiple unpackers.

# Motivation
Previously, all errors returned from `UnpackXxxEvent` were
indistinguishable without string matching. This is especially
problematic when processing logs sourced from `eth_getBlockReceipts`,
where a caller receives the full set of logs for a block across all
contracts and event types. In that context, a signature mismatch is
expected and should be skipped, while any other error (malformed data,
topic parsing failure) indicates something is genuinely wrong and should
halt execution:

```go
for _, log := range blockLogs {
    event, err := contract.UnpackTransferEvent(log)
    if errors.Is(err, gen.ErrTransferSignatureMismatch) {
        continue // not our event, expected
    }
    if err != nil {
        return fmt.Errorf("unexpected decode failure: %w", err) // alert
    }
    // process event
}
```

**Changes:**
- `abigen` template: generates a `ErrXxxSignatureMismatch` sentinel per
event and returns it on topic mismatch instead of an inline error
- Existing generated bindings & testdata: regenerated to reflect the
update

Implements #34075
2026-04-13 14:42:34 +02:00

250 lines
9.3 KiB
Smarty

// Code generated via abigen V2 - DO NOT EDIT.
// This file is a generated binding and any manual changes will be lost.
package {{.Package}}
import (
"bytes"
"math/big"
"errors"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/accounts/abi/bind/v2"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
)
// Reference imports to suppress errors if they are not otherwise used.
var (
_ = bytes.Equal
_ = errors.New
_ = big.NewInt
_ = common.Big1
_ = types.BloomLookup
_ = abi.ConvertType
)
{{$structs := .Structs}}
{{range $structs}}
// {{.Name}} is an auto generated low-level Go binding around an user-defined struct.
type {{.Name}} struct {
{{range $field := .Fields}}
{{capitalise $field.Name}} {{$field.Type}}{{end}}
}
{{end}}
{{range $contract := .Contracts}}
// {{.Type}}MetaData contains all meta data concerning the {{.Type}} contract.
var {{.Type}}MetaData = bind.MetaData{
ABI: "{{.InputABI}}",
{{if (index $.Libraries .Type) -}}
ID: "{{index $.Libraries .Type}}",
{{ else -}}
ID: "{{.Type}}",
{{end -}}
{{if .InputBin -}}
Bin: "0x{{.InputBin}}",
{{end -}}
{{if .Libraries -}}
Deps: []*bind.MetaData{
{{- range $name, $pattern := .Libraries}}
&{{$name}}MetaData,
{{- end}}
},
{{end}}
}
// {{.Type}} is an auto generated Go binding around an Ethereum contract.
type {{.Type}} struct {
abi abi.ABI
}
// New{{.Type}} creates a new instance of {{.Type}}.
func New{{.Type}}() *{{.Type}} {
parsed, err := {{.Type}}MetaData.ParseABI()
if err != nil {
panic(errors.New("invalid ABI: " + err.Error()))
}
return &{{.Type}}{abi: *parsed}
}
// Instance creates a wrapper for a deployed contract instance at the given address.
// Use this to create the instance object passed to abigen v2 library functions Call, Transact, etc.
func (c *{{.Type}}) Instance(backend bind.ContractBackend, addr common.Address) *bind.BoundContract {
return bind.NewBoundContract(addr, c.abi, backend, backend, backend)
}
{{ if .Constructor.Inputs }}
// PackConstructor is the Go binding used to pack the parameters required for
// contract deployment.
//
// Solidity: {{.Constructor.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) PackConstructor({{range .Constructor.Inputs}} {{.Name}} {{bindtype .Type $structs}}, {{end}}) []byte {
enc, err := {{ decapitalise $contract.Type}}.abi.Pack("" {{range .Constructor.Inputs}}, {{.Name}}{{end}})
if err != nil {
panic(err)
}
return enc
}
{{ end }}
{{range .Calls}}
// Pack{{.Normalized.Name}} is the Go binding used to pack the parameters required for calling
// the contract method with ID 0x{{printf "%x" .Original.ID}}. This method will panic if any
// invalid/nil inputs are passed.
//
// Solidity: {{.Original.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) Pack{{.Normalized.Name}}({{range .Normalized.Inputs}} {{.Name}} {{bindtype .Type $structs}}, {{end}}) []byte {
enc, err := {{ decapitalise $contract.Type}}.abi.Pack("{{.Original.Name}}" {{range .Normalized.Inputs}}, {{.Name}}{{end}})
if err != nil {
panic(err)
}
return enc
}
// TryPack{{.Normalized.Name}} is the Go binding used to pack the parameters required for calling
// the contract method with ID 0x{{printf "%x" .Original.ID}}. This method will return an error
// if any inputs are invalid/nil.
//
// Solidity: {{.Original.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) TryPack{{.Normalized.Name}}({{range .Normalized.Inputs}} {{.Name}} {{bindtype .Type $structs}}, {{end}}) ([]byte, error) {
return {{ decapitalise $contract.Type}}.abi.Pack("{{.Original.Name}}" {{range .Normalized.Inputs}}, {{.Name}}{{end}})
}
{{/* Unpack method is needed only when there are return args */}}
{{if .Normalized.Outputs }}
{{ if .Structured }}
// {{.Normalized.Name}}Output serves as a container for the return parameters of contract
// method {{ .Normalized.Name }}.
type {{.Normalized.Name}}Output struct {
{{range .Normalized.Outputs}}
{{capitalise .Name}} {{bindtype .Type $structs}}{{end}}
}
{{ end }}
// Unpack{{.Normalized.Name}} is the Go binding that unpacks the parameters returned
// from invoking the contract method with ID 0x{{printf "%x" .Original.ID}}.
//
// Solidity: {{.Original.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) Unpack{{.Normalized.Name}}(data []byte) (
{{- if .Structured}} {{.Normalized.Name}}Output,{{else}}
{{- range .Normalized.Outputs}} {{bindtype .Type $structs}},{{- end }}
{{- end }} error) {
out, err := {{ decapitalise $contract.Type}}.abi.Unpack("{{.Original.Name}}", data)
{{- if .Structured}}
outstruct := new({{.Normalized.Name}}Output)
if err != nil {
return *outstruct, err
}
{{- range $i, $t := .Normalized.Outputs}}
{{- if ispointertype .Type}}
outstruct.{{capitalise .Name}} = abi.ConvertType(out[{{$i}}], new({{underlyingbindtype .Type }})).({{bindtype .Type $structs}})
{{- else }}
outstruct.{{capitalise .Name}} = *abi.ConvertType(out[{{$i}}], new({{bindtype .Type $structs}})).(*{{bindtype .Type $structs}})
{{- end }}
{{- end }}
return *outstruct, nil{{else}}
if err != nil {
return {{range $i, $_ := .Normalized.Outputs}}{{if ispointertype .Type}}new({{underlyingbindtype .Type }}), {{else}}*new({{bindtype .Type $structs}}), {{end}}{{end}} err
}
{{- range $i, $t := .Normalized.Outputs}}
{{- if ispointertype .Type }}
out{{$i}} := abi.ConvertType(out[{{$i}}], new({{underlyingbindtype .Type}})).({{bindtype .Type $structs}})
{{- else }}
out{{$i}} := *abi.ConvertType(out[{{$i}}], new({{bindtype .Type $structs}})).(*{{bindtype .Type $structs}})
{{- end }}
{{- end}}
return {{range $i, $t := .Normalized.Outputs}}out{{$i}}, {{end}} nil
{{- end}}
}
{{end}}
{{end}}
{{range .Events}}
// {{$contract.Type}}{{.Normalized.Name}} represents a {{.Original.Name}} event raised by the {{$contract.Type}} contract.
type {{$contract.Type}}{{.Normalized.Name}} struct {
{{- range .Normalized.Inputs}}
{{ capitalise .Name}}
{{- if .Indexed}} {{ bindtopictype .Type $structs}}{{- else}} {{ bindtype .Type $structs}}{{ end }}
{{- end}}
Raw *types.Log // Blockchain specific contextual infos
}
const {{$contract.Type}}{{.Normalized.Name}}EventName = "{{.Original.Name}}"
// ContractEventName returns the user-defined event name.
func ({{$contract.Type}}{{.Normalized.Name}}) ContractEventName() string {
return {{$contract.Type}}{{.Normalized.Name}}EventName
}
// Unpack{{.Normalized.Name}}Event is the Go binding that unpacks the event data emitted
// by contract.
//
// Solidity: {{.Original.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) Unpack{{.Normalized.Name}}Event(log *types.Log) (*{{$contract.Type}}{{.Normalized.Name}}, error) {
event := "{{.Original.Name}}"
if len(log.Topics) == 0 {
return nil, bind.ErrNoEventSignature
}
if log.Topics[0] != {{ decapitalise $contract.Type}}.abi.Events[event].ID {
return nil, bind.ErrEventSignatureMismatch
}
out := new({{$contract.Type}}{{.Normalized.Name}})
if len(log.Data) > 0 {
if err := {{ decapitalise $contract.Type}}.abi.UnpackIntoInterface(out, event, log.Data); err != nil {
return nil, err
}
}
var indexed abi.Arguments
for _, arg := range {{ decapitalise $contract.Type}}.abi.Events[event].Inputs {
if arg.Indexed {
indexed = append(indexed, arg)
}
}
if err := abi.ParseTopics(out, indexed, log.Topics[1:]); err != nil {
return nil, err
}
out.Raw = log
return out, nil
}
{{end}}
{{ if .Errors }}
// UnpackError attempts to decode the provided error data using user-defined
// error definitions.
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) UnpackError(raw []byte) (any, error) {
{{- range $k, $v := .Errors}}
if bytes.Equal(raw[:4], {{ decapitalise $contract.Type}}.abi.Errors["{{.Normalized.Name}}"].ID.Bytes()[:4]) {
return {{ decapitalise $contract.Type}}.Unpack{{.Normalized.Name}}Error(raw[4:])
}
{{- end }}
return nil, errors.New("Unknown error")
}
{{ end }}
{{range .Errors}}
// {{$contract.Type}}{{.Normalized.Name}} represents a {{.Original.Name}} error raised by the {{$contract.Type}} contract.
type {{$contract.Type}}{{.Normalized.Name}} struct { {{range .Normalized.Inputs}}
{{capitalise .Name}} {{if .Indexed}}{{bindtopictype .Type $structs}}{{else}}{{bindtype .Type $structs}}{{end}}; {{end}}
}
// ErrorID returns the hash of canonical representation of the error's signature.
//
// Solidity: {{.Original.String}}
func {{$contract.Type}}{{.Normalized.Name}}ErrorID() common.Hash {
return common.HexToHash("{{.Original.ID}}")
}
// Unpack{{.Normalized.Name}}Error is the Go binding used to decode the provided
// error data into the corresponding Go error struct.
//
// Solidity: {{.Original.String}}
func ({{ decapitalise $contract.Type}} *{{$contract.Type}}) Unpack{{.Normalized.Name}}Error(raw []byte) (*{{$contract.Type}}{{.Normalized.Name}}, error) {
out := new({{$contract.Type}}{{.Normalized.Name}})
if err := {{ decapitalise $contract.Type}}.abi.UnpackIntoInterface(out, "{{.Normalized.Name}}", raw); err != nil {
return nil, err
}
return out, nil
}
{{end}}
{{end}}