fix slice pointer dive tag

mold.go

@@ -240,7 +240,9 @@ func (t *Transformer) setByField(ctx context.Context, orig reflect.Value, ct *cT
 				case reflect.Map:
 					err = t.setByMap(ctx, current, ct)
 				default:
-					err = ErrInvalidDive
+					if !current.IsNil() {
+						err = ErrInvalidDive
+					}
 				}
 				return
 
@@ -257,7 +259,6 @@ func (t *Transformer) setByField(ctx context.Context, orig reflect.Value, ct *cT
 						return
 					}
 					orig.Set(reflect.Indirect(newVal))
-					current, kind = t.extractType(orig)
 				} else {
 					if err = ct.fn(ctx, fieldLevel{
 						transformer: t,
@@ -268,6 +269,8 @@ func (t *Transformer) setByField(ctx context.Context, orig reflect.Value, ct *cT
 						return
 					}
 				}
+				current, kind = t.extractType(orig)
+
 				ct = ct.next
 			}
 		}

mold_test.go

@@ -678,3 +678,71 @@ func TestStructArray(t *testing.T) {
 	Equal(t, len(tt5.ArrNoTag), 1)
 	Equal(t, tt5.ArrNoTag[0].String, "")
 }
+
+func TestStructPtrArray(t *testing.T) {
+	type InnerStruct struct {
+		String string `s:"defaultStr"`
+	}
+
+	type Test struct {
+		Inner                *InnerStruct
+		ArrSetDefault        *[]InnerStruct `s:"defaultArr"`
+		ArrSetDefaultAndDive *[]InnerStruct `s:"defaultArr,dive"`
+		ArrDive              *[]InnerStruct `s:"dive"`
+		ArrNoTag             *[]InnerStruct
+	}
+
+	set := New()
+	set.SetTagName("s")
+	set.Register("defaultArr", func(ctx context.Context, fl FieldLevel) error {
+		if HasValue(fl.Field()) {
+			return nil
+		}
+		arr := make([]InnerStruct, 2)
+		fl.Field().Set(reflect.ValueOf(&arr))
+		return nil
+	})
+	set.Register("defaultStr", func(ctx context.Context, fl FieldLevel) error {
+		if fl.Field().String() == "ok" {
+			return errors.New("ALREADY OK")
+		}
+		fl.Field().SetString("default")
+		return nil
+	})
+
+	tt1 := Test{
+		Inner:                &InnerStruct{},
+		ArrSetDefault:        &[]InnerStruct{{}},
+		ArrSetDefaultAndDive: &[]InnerStruct{{}},
+		ArrDive:              &[]InnerStruct{{}},
+		ArrNoTag:             &[]InnerStruct{{}},
+	}
+
+	err := set.Struct(context.Background(), &tt1)
+	Equal(t, err, nil)
+	Equal(t, len(*tt1.ArrSetDefault), 1)
+	Equal(t, (*tt1.ArrSetDefault)[0].String, "")
+	Equal(t, len(*tt1.ArrSetDefaultAndDive), 1)
+	Equal(t, (*tt1.ArrSetDefaultAndDive)[0].String, "default")
+	Equal(t, len(*tt1.ArrDive), 1)
+	Equal(t, (*tt1.ArrDive)[0].String, "default")
+	Equal(t, len(*tt1.ArrNoTag), 1)
+	Equal(t, (*tt1.ArrNoTag)[0].String, "")
+
+	Equal(t, tt1.Inner.String, "default")
+
+	tt2 := Test{}
+
+	err = set.Struct(context.Background(), &tt2)
+	Equal(t, err, nil)
+	Equal(t, len(*tt2.ArrSetDefault), 2)
+	Equal(t, (*tt2.ArrSetDefault)[0].String, "")
+	Equal(t, (*tt2.ArrSetDefault)[1].String, "")
+	Equal(t, len(*tt2.ArrSetDefaultAndDive), 2)
+	Equal(t, (*tt2.ArrSetDefaultAndDive)[0].String, "default")
+	Equal(t, (*tt2.ArrSetDefaultAndDive)[1].String, "default")
+	Equal(t, tt2.ArrDive, nil)
+	Equal(t, tt2.ArrNoTag, nil)
+
+	Equal(t, tt2.Inner, nil)
+}