[BUG] unexpected quote when handling json.Marshaler and ,string tag meantime

[AsterDY]

Reproducible codes

func TestIssue670_JSONMarshaler(t *testing.T) {
	var obj = Issue670JSONMarshaler{ D: Date(time.Now().Unix()) }
	so, _ := sonic.MarshalString(obj)
	eo, _ := json.Marshal(obj)
	assert.Equal(t, string(eo), so)
	println(string(eo))
}

func TestIssue670_JSONUnmarshaler(t *testing.T) {
	// match
	eo := []byte(`{"D":"2021-08-26","E":1}`)
	et := reflect.TypeOf(Issue670JSONMarshaler{})
	testUnmarshal(t, eo, et, true)

	// mismatch
	eo = []byte(`{"D":11,"E":1}`)
	testUnmarshal(t, eo, et, true)

	// null
	eo = []byte(`{"D":null,"E":1}`)
	testUnmarshal(t, eo, et, true)
}

func testUnmarshal(t *testing.T, eo []byte, rt reflect.Type, checkobj bool) {
	obj := reflect.New(rt).Interface()
	println(string(eo))
	println("sonic")
	es := sonic.Unmarshal(eo, obj)
	obj2 := reflect.New(rt).Interface()
	println("std")
	ee := json.Unmarshal(eo, obj2)
	assert.Equal(t, ee ==nil, es == nil, es)
	if checkobj {
		assert.Equal(t, obj2, obj)
	}
	fmt.Printf("std: %v, obj: %#v", ee, obj2)
	fmt.Printf("sonic error: %v, obj: %#v", es, obj)
}

Result

                 Error:      	Not equal: 
        	            	expected: "{\"delivery_date\":\"2024-07-31\"}"
        	            	actual  : "{\"delivery_date\":\"\"2024-07-31\"\"}"
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1 +1 @@
        	            	-{"delivery_date":"2024-07-31"}
        	            	+{"delivery_date":""2024-07-31""}

        	
        	Error:      	Not equal: 
        	            	expected: true
        	            	actual  : false
        	Test:       	TestIssue670_JSONUnmarshaler
        	Messages:   	"Syntax error at index 10: invalid char\n\n\t{\"D\":\"2021-08-26\",\"E\":1}\n\t..........^.............\n"
    
        	Error:      	Not equal: 
        	            	expected: &issue_test.Issue670JSONMarshaler{D:1629936000, E:1}
        	            	actual  : &issue_test.Issue670JSONMarshaler{D:2021, E:0}
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1,4 +1,4 @@
        	            	 (*issue_test.Issue670JSONMarshaler)({
        	            	- D: (issue_test.Date) 1629936000,
        	            	- E: (int) 1
        	            	+ D: (issue_test.Date) 2021,
        	            	+ E: (int) 0
        	            	 })
        	Test:       	TestIssue670_JSONUnmarshaler
  
        	Error:      	Not equal: 
        	            	expected: &issue_test.Issue670JSONMarshaler{D:0, E:1}
        	            	actual  : &issue_test.Issue670JSONMarshaler{D:0, E:0}
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -2,3 +2,3 @@
        	            	  D: (issue_test.Date) 0,
        	            	- E: (int) 1
        	            	+ E: (int) 0
        	            	 })
        	Test:       	TestIssue670_JSONUnmarshaler

Reason

• when encounter json.Marshaler fields, std didn't consider ,string tag (to quote), but sonic handle both (https://github.com/bytedance/sonic/blob/main/internal/encoder/compiler.go#L607)

[AsterDY]

fixed by #682