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https://github.com/ethereum/go-ethereum.git
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# 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
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| v2 | ||
| old.go | ||