Merge pull request #40 from goccy/feature/fix-anonymous-struct

Fix anonymous struct fields

encode_compile.go

@@ -622,7 +622,6 @@ type structFieldPair struct {
 }
 
 func (e *Encoder) anonymousStructFieldPairMap(typ *rtype, tags structTags, valueCode *structFieldCode) map[string][]structFieldPair {
-	//fmt.Println("type = ", typ, "valueCode = ", valueCode.dump())
 	anonymousFields := map[string][]structFieldPair{}
 	f := valueCode
 	var prevAnonymousField *structFieldCode

encode_opcode.go

@@ -112,15 +112,24 @@ func (c *opcode) dump() string {
 	codes := []string{}
 	for code := c; code.op != opEnd; {
 		indent := strings.Repeat(" ", code.indent)
-		codes = append(codes, fmt.Sprintf("%s%s ( %p )", indent, code.op, unsafe.Pointer(code)))
 		switch code.op.codeType() {
 		case codeArrayElem:
+			codes = append(codes, fmt.Sprintf("%s%s ( %p )", indent, code.op, unsafe.Pointer(code)))
 			code = code.toArrayElemCode().end
 		case codeSliceElem:
+			codes = append(codes, fmt.Sprintf("%s%s ( %p )", indent, code.op, unsafe.Pointer(code)))
 			code = code.toSliceElemCode().end
 		case codeMapKey:
+			codes = append(codes, fmt.Sprintf("%s%s ( %p )", indent, code.op, unsafe.Pointer(code)))
 			code = code.toMapKeyCode().end
+		case codeStructField:
+			sf := code.toStructFieldCode()
+			key := sf.displayKey
+			offset := sf.offset
+			codes = append(codes, fmt.Sprintf("%s%s [%s:%d] ( %p )", indent, code.op, key, offset, unsafe.Pointer(code)))
+			code = code.next
 		default:
+			codes = append(codes, fmt.Sprintf("%s%s ( %p )", indent, code.op, unsafe.Pointer(code)))
 			code = code.next
 		}
 	}

encode_test.go

@@ -1392,3 +1392,180 @@ func TestDuplicatedFieldDisappears(t *testing.T) {
 		t.Fatalf("Marshal: got %s want %s", got, want)
 	}
 }
+
+func TestAnonymousFields(t *testing.T) {
+	tests := []struct {
+		label     string             // Test name
+		makeInput func() interface{} // Function to create input value
+		want      string             // Expected JSON output
+	}{{
+		// Both S1 and S2 have a field named X. From the perspective of S,
+		// it is ambiguous which one X refers to.
+		// This should not serialize either field.
+		label: "AmbiguousField",
+		makeInput: func() interface{} {
+			type (
+				S1 struct{ x, X int }
+				S2 struct{ x, X int }
+				S  struct {
+					S1
+					S2
+				}
+			)
+			return S{S1{1, 2}, S2{3, 4}}
+		},
+		want: `{}`,
+	}, {
+		label: "DominantField",
+		// Both S1 and S2 have a field named X, but since S has an X field as
+		// well, it takes precedence over S1.X and S2.X.
+		makeInput: func() interface{} {
+			type (
+				S1 struct{ x, X int }
+				S2 struct{ x, X int }
+				S  struct {
+					S1
+					S2
+					x, X int
+				}
+			)
+			return S{S1{1, 2}, S2{3, 4}, 5, 6}
+		},
+		want: `{"X":6}`,
+	}, {
+		// Unexported embedded field of non-struct type should not be serialized.
+		label: "UnexportedEmbeddedInt",
+		makeInput: func() interface{} {
+			type (
+				myInt int
+				S     struct{ myInt }
+			)
+			return S{5}
+		},
+		want: `{}`,
+	}, {
+		// Exported embedded field of non-struct type should be serialized.
+		label: "ExportedEmbeddedInt",
+		makeInput: func() interface{} {
+			type (
+				MyInt int
+				S     struct{ MyInt }
+			)
+			return S{5}
+		},
+		want: `{"MyInt":5}`,
+	}, {
+		// Unexported embedded field of pointer to non-struct type
+		// should not be serialized.
+		label: "UnexportedEmbeddedIntPointer",
+		makeInput: func() interface{} {
+			type (
+				myInt int
+				S     struct{ *myInt }
+			)
+			s := S{new(myInt)}
+			*s.myInt = 5
+			return s
+		},
+		want: `{}`,
+	}, {
+		// Exported embedded field of pointer to non-struct type
+		// should be serialized.
+		label: "ExportedEmbeddedIntPointer",
+		makeInput: func() interface{} {
+			type (
+				MyInt int
+				S     struct{ *MyInt }
+			)
+			s := S{new(MyInt)}
+			*s.MyInt = 5
+			return s
+		},
+		want: `{"MyInt":5}`,
+	}, {
+		// Exported fields of embedded structs should have their
+		// exported fields be serialized regardless of whether the struct types
+		// themselves are exported.
+		label: "EmbeddedStruct",
+		makeInput: func() interface{} {
+			type (
+				s1 struct{ x, X int }
+				S2 struct{ y, Y int }
+				S  struct {
+					s1
+					S2
+				}
+			)
+			return S{s1{1, 2}, S2{3, 4}}
+		},
+		want: `{"X":2,"Y":4}`,
+	}, {
+		// Exported fields of pointers to embedded structs should have their
+		// exported fields be serialized regardless of whether the struct types
+		// themselves are exported.
+		label: "EmbeddedStructPointer",
+		makeInput: func() interface{} {
+			type (
+				s1 struct{ x, X int }
+				S2 struct{ y, Y int }
+				S  struct {
+					*s1
+					*S2
+				}
+			)
+			return S{&s1{1, 2}, &S2{3, 4}}
+		},
+		want: `{"X":2,"Y":4}`,
+	}, {
+		// Exported fields on embedded unexported structs at multiple levels
+		// of nesting should still be serialized.
+		label: "NestedStructAndInts",
+		makeInput: func() interface{} {
+			type (
+				MyInt1 int
+				MyInt2 int
+				myInt  int
+				s2     struct {
+					MyInt2
+					myInt
+				}
+				s1 struct {
+					MyInt1
+					myInt
+					s2
+				}
+				S struct {
+					s1
+					myInt
+				}
+			)
+			return S{s1{1, 2, s2{3, 4}}, 6}
+		},
+		want: `{"MyInt1":1,"MyInt2":3}`,
+	}, {
+		// If an anonymous struct pointer field is nil, we should ignore
+		// the embedded fields behind it. Not properly doing so may
+		// result in the wrong output or reflect panics.
+		label: "EmbeddedFieldBehindNilPointer",
+		makeInput: func() interface{} {
+			type (
+				S2 struct{ Field string }
+				S  struct{ *S2 }
+			)
+			return S{}
+		},
+		want: `{}`,
+	}}
+
+	for i, tt := range tests {
+		t.Run(tt.label, func(t *testing.T) {
+			b, err := json.Marshal(tt.makeInput())
+			if err != nil {
+				t.Fatalf("%d: Marshal() = %v, want nil error", i, err)
+			}
+			if string(b) != tt.want {
+				t.Fatalf("%d: Marshal() = %q, want %q", i, b, tt.want)
+			}
+		})
+	}
+}

encode_vm.go

@@ -538,7 +538,11 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHead {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end.next
 			} else {
 				e.encodeByte('{')
@@ -566,12 +570,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadInt {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeInt(e.ptrToInt(ptr))
+				e.encodeInt(e.ptrToInt(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -585,7 +593,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeInt(e.ptrToInt(ptr))
+				e.encodeInt(e.ptrToInt(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -596,12 +604,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadInt8 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeInt8(e.ptrToInt8(ptr))
+				e.encodeInt8(e.ptrToInt8(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -615,7 +627,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeInt8(e.ptrToInt8(ptr))
+				e.encodeInt8(e.ptrToInt8(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -626,12 +638,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadInt16 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeInt16(e.ptrToInt16(ptr))
+				e.encodeInt16(e.ptrToInt16(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -645,7 +661,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeInt16(e.ptrToInt16(ptr))
+				e.encodeInt16(e.ptrToInt16(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -656,12 +672,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadInt32 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeInt32(e.ptrToInt32(ptr))
+				e.encodeInt32(e.ptrToInt32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -675,7 +695,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeInt32(e.ptrToInt32(ptr))
+				e.encodeInt32(e.ptrToInt32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -686,12 +706,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadInt64 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeInt64(e.ptrToInt64(ptr))
+				e.encodeInt64(e.ptrToInt64(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -705,7 +729,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeInt64(e.ptrToInt64(ptr))
+				e.encodeInt64(e.ptrToInt64(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -716,12 +740,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadUint {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeUint(e.ptrToUint(ptr))
+				e.encodeUint(e.ptrToUint(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -735,7 +763,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeUint(e.ptrToUint(ptr))
+				e.encodeUint(e.ptrToUint(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -746,12 +774,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadUint8 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeUint8(e.ptrToUint8(ptr))
+				e.encodeUint8(e.ptrToUint8(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -765,7 +797,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeUint8(e.ptrToUint8(ptr))
+				e.encodeUint8(e.ptrToUint8(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -776,12 +808,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadUint16 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeUint16(e.ptrToUint16(ptr))
+				e.encodeUint16(e.ptrToUint16(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -795,7 +831,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeUint16(e.ptrToUint16(ptr))
+				e.encodeUint16(e.ptrToUint16(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -806,12 +842,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadUint32 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeUint32(e.ptrToUint32(ptr))
+				e.encodeUint32(e.ptrToUint32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -825,7 +865,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeUint32(e.ptrToUint32(ptr))
+				e.encodeUint32(e.ptrToUint32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -836,12 +876,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadUint64 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeUint64(e.ptrToUint64(ptr))
+				e.encodeUint64(e.ptrToUint64(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -855,7 +899,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeUint64(e.ptrToUint64(ptr))
+				e.encodeUint64(e.ptrToUint64(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -866,12 +910,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadFloat32 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeFloat32(e.ptrToFloat32(ptr))
+				e.encodeFloat32(e.ptrToFloat32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -885,7 +933,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeFloat32(e.ptrToFloat32(ptr))
+				e.encodeFloat32(e.ptrToFloat32(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -896,10 +944,14 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadFloat64 {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
-				v := e.ptrToFloat64(ptr)
+				v := e.ptrToFloat64(ptr + field.offset)
 				if math.IsInf(v, 0) || math.IsNaN(v) {
 					return &UnsupportedValueError{
 						Value: reflect.ValueOf(v),
@@ -921,7 +973,7 @@ func (e *Encoder) run(code *opcode) error {
 			if ptr == 0 {
 				code = field.end
 			} else {
-				v := e.ptrToFloat64(ptr)
+				v := e.ptrToFloat64(ptr + field.offset)
 				if math.IsInf(v, 0) || math.IsNaN(v) {
 					return &UnsupportedValueError{
 						Value: reflect.ValueOf(v),
@@ -940,12 +992,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadString {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeString(e.ptrToString(ptr))
+				e.encodeString(e.ptrToString(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -959,7 +1015,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeString(e.ptrToString(ptr))
+				e.encodeString(e.ptrToString(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -970,12 +1026,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadBool {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				e.encodeBool(e.ptrToBool(ptr))
+				e.encodeBool(e.ptrToBool(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -989,7 +1049,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				e.encodeBool(e.ptrToBool(ptr))
+				e.encodeBool(e.ptrToBool(ptr + field.offset))
 				field.nextField.ptr = ptr
 				code = field.next
 			}
@@ -1000,12 +1060,16 @@ func (e *Encoder) run(code *opcode) error {
 			field := code.toStructFieldCode()
 			ptr := field.ptr
 			if ptr == 0 {
-				e.encodeNull()
+				if code.op == opStructFieldPtrHeadBytes {
+					e.encodeNull()
+				} else {
+					e.encodeBytes([]byte{'{', '}'})
+				}
 				code = field.end
 			} else {
 				e.encodeByte('{')
 				e.encodeBytes(field.key)
-				s := base64.StdEncoding.EncodeToString(e.ptrToBytes(ptr))
+				s := base64.StdEncoding.EncodeToString(e.ptrToBytes(ptr + field.offset))
 				e.encodeByte('"')
 				e.encodeBytes(*(*[]byte)(unsafe.Pointer(&s)))
 				e.encodeByte('"')
@@ -1022,7 +1086,7 @@ func (e *Encoder) run(code *opcode) error {
 				code = field.end
 			} else {
 				e.encodeBytes(field.key)
-				s := base64.StdEncoding.EncodeToString(e.ptrToBytes(code.ptr))
+				s := base64.StdEncoding.EncodeToString(e.ptrToBytes(code.ptr + field.offset))
 				e.encodeByte('"')
 				e.encodeBytes(*(*[]byte)(unsafe.Pointer(&s)))
 				e.encodeByte('"')
@@ -1043,7 +1107,7 @@ func (e *Encoder) run(code *opcode) error {
 				e.encodeBytes(field.key)
 				v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 					typ: code.typ,
-					ptr: unsafe.Pointer(ptr),
+					ptr: unsafe.Pointer(ptr + field.offset),
 				}))
 				rv := reflect.ValueOf(v)
 				if rv.Type().Kind() == reflect.Interface && rv.IsNil() {
@@ -1084,7 +1148,7 @@ func (e *Encoder) run(code *opcode) error {
 				e.encodeBytes(field.key)
 				v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 					typ: code.typ,
-					ptr: unsafe.Pointer(ptr),
+					ptr: unsafe.Pointer(ptr + field.offset),
 				}))
 				rv := reflect.ValueOf(v)
 				if rv.Type().Kind() == reflect.Interface && rv.IsNil() {
@@ -1127,7 +1191,7 @@ func (e *Encoder) run(code *opcode) error {
 				e.encodeBytes(field.key)
 				v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 					typ: code.typ,
-					ptr: unsafe.Pointer(ptr),
+					ptr: unsafe.Pointer(ptr + field.offset),
 				}))
 				rv := reflect.ValueOf(v)
 				if rv.Type().Kind() == reflect.Interface && rv.IsNil() {
@@ -1158,7 +1222,7 @@ func (e *Encoder) run(code *opcode) error {
 				e.encodeBytes(field.key)
 				v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 					typ: code.typ,
-					ptr: unsafe.Pointer(ptr),
+					ptr: unsafe.Pointer(ptr + field.offset),
 				}))
 				rv := reflect.ValueOf(v)
 				if rv.Type().Kind() == reflect.Interface && rv.IsNil() {

struct_field.go

@@ -10,9 +10,15 @@ func getTag(field reflect.StructField) string {
 }
 
 func isIgnoredStructField(field reflect.StructField) bool {
-	if field.PkgPath != "" && !field.Anonymous {
+	if field.PkgPath != "" {
-		// private field
+		if field.Anonymous {
-		return true
+			if !(field.Type.Kind() == reflect.Ptr && field.Type.Elem().Kind() == reflect.Struct) && field.Type.Kind() != reflect.Struct {
+				return true
+			}
+		} else {
+			// private field
+			return true
+		}
 	}
 	tag := getTag(field)
 	if tag == "-" {