fix: fixed a problem with NextField being wrong when combining struct…

…ure embedding and omitempty (#442)

fix #441

encode_test.go

@@ -2694,3 +2694,19 @@ func TestIssue426(t *testing.T) {
 	b, _ := json.Marshal(s)
 	assertEq(t, "unexpected result", `{"I":null,"Val":"456"}`, string(b))
 }
+
+func TestIssue441(t *testing.T) {
+	type A struct {
+		Y string `json:"y,omitempty"`
+	}
+
+	type B struct {
+		X *int `json:"x,omitempty"`
+		A
+		Z int `json:"z,omitempty"`
+	}
+
+	b, err := json.Marshal(B{})
+	assertErr(t, err)
+	assertEq(t, "unexpected result", "{}", string(b))
+}

internal/encoder/code.go

@@ -397,7 +397,7 @@ func (c *StructCode) lastFieldCode(field *StructFieldCode, firstField *Opcode) *
 func (c *StructCode) lastAnonymousFieldCode(firstField *Opcode) *Opcode {
 	// firstField is special StructHead operation for anonymous structure.
 	// So, StructHead's next operation is truly struct head operation.
-	for firstField.Op == OpStructHead {
+	for firstField.Op == OpStructHead || firstField.Op == OpStructField {
 		firstField = firstField.Next
 	}
 	lastField := firstField