Fix template extend

option/template.go

@@ -7,9 +7,10 @@ import (
 	"github.com/sagernet/sing/common/json"
 )
 
-type Template struct {
-	Name   string `json:"name,omitempty"`
-	Extend string `json:"extend,omitempty"`
+type _Template struct {
+	RawMessage json.RawMessage `json:"-"`
+	Name       string          `json:"name,omitempty"`
+	Extend     string          `json:"extend,omitempty"`
 
 	// Global
 
@@ -72,6 +73,21 @@ type Template struct {
 	MemoryLimit option.MemoryBytes `json:"memory_limit,omitempty"`
 }
 
+type Template _Template
+
+func (t *Template) MarshalJSON() ([]byte, error) {
+	return json.Marshal((*_Template)(t))
+}
+
+func (t *Template) UnmarshalJSON(bytes []byte) error {
+	err := json.Unmarshal(bytes, (*_Template)(t))
+	if err != nil {
+		return err
+	}
+	t.RawMessage = bytes
+	return nil
+}
+
 type _RuleSet struct {
 	Type           string               `json:"type,omitempty"`
 	DefaultOptions option.RuleSet       `json:"-"`

template/manager.go

@@ -7,6 +7,7 @@ import (
 	"github.com/sagernet/serenity/option"
 	C "github.com/sagernet/sing-box/constant"
 	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/json"
 	"github.com/sagernet/sing/common/json/badjson"
 	"github.com/sagernet/sing/common/logger"
 )
@@ -40,10 +41,15 @@ func extendTemplate(rawTemplates []option.Template, root, current option.Templat
 		}
 		next = newNext
 	}
-	newTemplate, err := badjson.Merge(next, current)
+	newRawTemplate, err := badjson.MergeJSON(next.RawMessage, current.RawMessage)
 	if err != nil {
 		return option.Template{}, E.Cause(err, "initialize template[", current.Name, "]: merge extended template: ", current.Extend)
 	}
+	newTemplate, err := json.UnmarshalExtended[option.Template](newRawTemplate)
+	if err != nil {
+		return option.Template{}, E.Cause(err, "initialize template[", current.Name, "]: unmarshal extended template: ", current.Extend)
+	}
+	newTemplate.RawMessage = newRawTemplate
 	return newTemplate, nil
 }