Question

What is the exact behavior of `errors.Is(err, ErrNotFound)` in this example, considering that `ErrNotFound` is wrapped?

```
var ErrNotFound = errors.New("not found")

func find() error {
	return fmt.Errorf("db error: %w", ErrNotFound)
}

func main() {
	err := find()
	// Quel comportement pour cette vérification ?
	fmt.Println(errors.Is(err, ErrNotFound))
}
```

Accepted Answer

It returns true because it walks the error chain.

Answer

It returns false because wrapped errors are not comparable.

Answer

It returns true only if the error is compared by value.

Answer

It returns false because the error is wrapped by fmt.Errorf.

Question from the Go test