fix custom array type with omitempty

internal/encoder/encoder.go

@@ -589,6 +589,8 @@ func IsNilForMarshaler(v interface{}) bool {
 		return rv.IsNil()
 	case reflect.Slice:
 		return rv.IsNil() || rv.Len() == 0
+	case reflect.Array:
+		return rv.IsZero()
 	case reflect.String:
 		return rv.Len() == 0
 	}

test/cover/cover_array_test.go

@@ -8,6 +8,14 @@ import (
 	"github.com/goccy/go-json"
 )
 
+type customArray [2]int
+
+type customArrayWithMarshaler [2]int
+
+func (b customArrayWithMarshaler) MarshalJSON() ([]byte, error) {
+	return json.Marshal([2]int(b))
+}
+
 func TestCoverArray(t *testing.T) {
 	type structArray struct {
 		A [2]int `json:"a"`
@@ -47,6 +55,24 @@ func TestCoverArray(t *testing.T) {
 		A *[2]*int `json:"a,string"`
 	}
 
+	type structCustomArrayOmitEmpty struct {
+		A customArray `json:"a,omitempty"`
+	}
+
+	type structSecondFieldCustomArrayOmitEmpty struct {
+		C [2]int      `json:"c"`
+		A customArray `json:"a,omitempty"`
+	}
+
+	type structCustomArrayWithMarshalerOmitEmpty struct {
+		A customArrayWithMarshaler `json:"a,omitempty"`
+	}
+
+	type structSecondFieldCustomArrayWithMarshalerOmitEmpty struct {
+		C [2]int                   `json:"c"`
+		A customArrayWithMarshaler `json:"a,omitempty"`
+	}
+
 	tests := []struct {
 		name string
 		data interface{}
@@ -1421,6 +1447,46 @@ func TestCoverArray(t *testing.T) {
 				B:                    [2]int{1},
 			},
 		},
+		{
+			name: "AnonymousHeadCustomArrayOmitEmpty",
+			data: struct {
+				structCustomArrayOmitEmpty
+				B customArray `json:"b,omitempty"`
+			}{
+				structCustomArrayOmitEmpty: structCustomArrayOmitEmpty{A: customArray{-1}},
+				B:                          [2]int{1},
+			},
+		},
+		{
+			name: "AnonymousHeadCustomArrayOmitEmpty",
+			data: struct {
+				structCustomArrayOmitEmpty
+				B customArray `json:"b,omitempty"`
+			}{
+				structCustomArrayOmitEmpty: structCustomArrayOmitEmpty{A: customArray{-1}},
+				B:                          [2]int{1},
+			},
+		},
+		{
+			name: "AnonymousHeadCustomArrayWithMarshalerOmitEmpty",
+			data: struct {
+				structCustomArrayWithMarshalerOmitEmpty
+				B customArrayWithMarshaler `json:"b,omitempty"`
+			}{
+				structCustomArrayWithMarshalerOmitEmpty: structCustomArrayWithMarshalerOmitEmpty{A: customArrayWithMarshaler{-1}},
+				B:                                       [2]int{1},
+			},
+		},
+		{
+			name: "AnonymousHeadCustomArrayWithMarshalerOmitEmpty",
+			data: struct {
+				structCustomArrayWithMarshalerOmitEmpty
+				B customArrayWithMarshaler `json:"b,omitempty"`
+			}{
+				structCustomArrayWithMarshalerOmitEmpty: structCustomArrayWithMarshalerOmitEmpty{A: customArrayWithMarshaler{-1}},
+				B:                                       [2]int{1},
+			},
+		},
 		{
 			name: "AnonymousHeadArrayString",
 			data: struct {