chore(core/types): add Test_Body_hasOptionalFields to enforce hasLaterOptionalField is up to date

core/types/block.internal.libevm_test.go

@@ -0,0 +1,40 @@
+package types
+
+import (
+	"reflect"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBody_hasAnyOptionalFieldSet(t *testing.T) {
+	t.Parallel()
+
+	var body Body
+
+	assert.False(t, body.hasAnyOptionalFieldSet(), "body has no optional field set")
+
+	v := reflect.ValueOf(&body).Elem()
+	for i := 0; i < v.NumField(); i++ {
+		fieldType := v.Type().Field(i)
+		tag := fieldType.Tag.Get("rlp")
+		if !slices.Contains(strings.Split(tag, ","), "optional") {
+			continue
+		}
+
+		field := v.Field(i)
+		before := field.Interface()
+		switch field.Kind() {
+		case reflect.Slice:
+			slice := reflect.MakeSlice(field.Type(), 1, 1)
+			field.Set(slice)
+		default:
+			t.Errorf("unexpected field kind %q for field %q", field.Kind(), fieldType.Name)
+		}
+
+		assert.Truef(t, body.hasAnyOptionalFieldSet(), "body has the optional field %q set", fieldType.Name)
+		field.Set(reflect.ValueOf(before)) // reset the field
+	}
+}

core/types/block.libevm.go

@@ -137,7 +137,7 @@ func (b *Body) EncodeRLP(dst io.Writer) error {
 			return err
 		}
 
-		hasLaterOptionalField := b.Withdrawals != nil
+		hasLaterOptionalField := b.hasAnyOptionalFieldSet()
 		if err := b.hooks().AppendRLPFields(w, hasLaterOptionalField); err != nil {
 			return err
 		}
@@ -148,6 +148,10 @@ func (b *Body) EncodeRLP(dst io.Writer) error {
 	})
 }
 
+func (b *Body) hasAnyOptionalFieldSet() bool {
+	return b.Withdrawals != nil
+}
+
 // DecodeRLP implements the [rlp.Decoder] interface.
 func (b *Body) DecodeRLP(s *rlp.Stream) error {
 	return s.FromList(func() error {