Fix bug in handling on anon structs which embed other structs

If the anon struct embeds another struct _and_ contains fields of its own,
there were cases where the generated code would ignore the anon struct's own
fields.

This happened because when checking if the anon struct implements a marshaling
interface, the reflect package returns true if the anon struct's _embedded
struct_ implements that interface. But using that interface means that the
other fields in the anon struct are ignored.

Author: autarch

gen/decoder.go

@@ -61,26 +61,34 @@ var customDecoders = map[string]string{
 func (g *Generator) genTypeDecoder(t reflect.Type, out string, tags fieldTags, indent int) error {
 	ws := strings.Repeat("  ", indent)
 
-	unmarshalerIface := reflect.TypeOf((*easyjson.Unmarshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(unmarshalerIface) {
-		fmt.Fprintln(g.out, ws+"("+out+").UnmarshalEasyJSON(in)")
-		return nil
-	}
+	// If the type is unnamed, then this is an anonymous struct. If that anon
+	// struct embeds another, named struct that implements one of these
+	// interfaces, then Implements(...) will return true, even if the anon
+	// struct has other fields. That causes us to skip code gen for those
+	// extra fields. This addresses
+	// https://github.com/mailru/easyjson/issues/337.
+	if t.Name() != "" {
+		unmarshalerIface := reflect.TypeOf((*easyjson.Unmarshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(unmarshalerIface) {
+			fmt.Fprintln(g.out, ws+"("+out+").UnmarshalEasyJSON(in)")
+			return nil
+		}
 
-	unmarshalerIface = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(unmarshalerIface) {
-		fmt.Fprintln(g.out, ws+"if data := in.Raw(); in.Ok() {")
-		fmt.Fprintln(g.out, ws+"  in.AddError( ("+out+").UnmarshalJSON(data) )")
-		fmt.Fprintln(g.out, ws+"}")
-		return nil
-	}
+		unmarshalerIface = reflect.TypeOf((*json.Unmarshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(unmarshalerIface) {
+			fmt.Fprintln(g.out, ws+"if data := in.Raw(); in.Ok() {")
+			fmt.Fprintln(g.out, ws+"  in.AddError( ("+out+").UnmarshalJSON(data) )")
+			fmt.Fprintln(g.out, ws+"}")
+			return nil
+		}
 
-	unmarshalerIface = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(unmarshalerIface) {
-		fmt.Fprintln(g.out, ws+"if data := in.UnsafeBytes(); in.Ok() {")
-		fmt.Fprintln(g.out, ws+"  in.AddError( ("+out+").UnmarshalText(data) )")
-		fmt.Fprintln(g.out, ws+"}")
-		return nil
+		unmarshalerIface = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(unmarshalerIface) {
+			fmt.Fprintln(g.out, ws+"if data := in.UnsafeBytes(); in.Ok() {")
+			fmt.Fprintln(g.out, ws+"  in.AddError( ("+out+").UnmarshalText(data) )")
+			fmt.Fprintln(g.out, ws+"}")
+			return nil
+		}
 	}
 
 	err := g.genTypeDecoderNoCheck(t, out, tags, indent)

gen/encoder.go

@@ -94,22 +94,25 @@ func parseFieldTags(f reflect.StructField) fieldTags {
 func (g *Generator) genTypeEncoder(t reflect.Type, in string, tags fieldTags, indent int, assumeNonEmpty bool) error {
 	ws := strings.Repeat("  ", indent)
 
-	marshalerIface := reflect.TypeOf((*easyjson.Marshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(marshalerIface) {
-		fmt.Fprintln(g.out, ws+"("+in+").MarshalEasyJSON(out)")
-		return nil
-	}
+	// See the comment in genTypeDecoder for why we check the name.
+	if t.Name() != "" {
+		marshalerIface := reflect.TypeOf((*easyjson.Marshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(marshalerIface) {
+			fmt.Fprintln(g.out, ws+"("+in+").MarshalEasyJSON(out)")
+			return nil
+		}
 
-	marshalerIface = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(marshalerIface) {
-		fmt.Fprintln(g.out, ws+"out.Raw( ("+in+").MarshalJSON() )")
-		return nil
-	}
+		marshalerIface = reflect.TypeOf((*json.Marshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(marshalerIface) {
+			fmt.Fprintln(g.out, ws+"out.Raw( ("+in+").MarshalJSON() )")
+			return nil
+		}
 
-	marshalerIface = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
-	if reflect.PtrTo(t).Implements(marshalerIface) {
-		fmt.Fprintln(g.out, ws+"out.RawText( ("+in+").MarshalText() )")
-		return nil
+		marshalerIface = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+		if reflect.PtrTo(t).Implements(marshalerIface) {
+			fmt.Fprintln(g.out, ws+"out.RawText( ("+in+").MarshalText() )")
+			return nil
+		}
 	}
 
 	err := g.genTypeEncoderNoCheck(t, in, tags, indent, assumeNonEmpty)

tests/basic_test.go

@@ -59,6 +59,7 @@ var testCases = []struct {
 	{&myTypeDeclaredValue, myTypeDeclaredString},
 	{&myTypeNotSkippedValue, myTypeNotSkippedString},
 	{&intern, internString},
+	{&embedAnonWithEmbedValue, embedAnonWithEmbedString},
 }
 
 func TestMarshal(t *testing.T) {

tests/data.go

@@ -820,3 +820,27 @@ type MyUInt8Array [2]MyUInt8
 var myUInt8ArrayValue = MyUInt8Array{1, 2}
 
 var myUInt8ArrayString = `[1,2]`
+
+type GrandChild struct {
+	V string `json:"v"`
+}
+
+//easyjson:json
+type EmbedAnonWithEmbed struct {
+	Child struct {
+		GrandChild
+		Sibling string `json:"sibling"`
+	} `json:"child"`
+}
+
+var embedAnonWithEmbedValue = EmbedAnonWithEmbed{
+	Child: struct {
+		GrandChild
+		Sibling string `json:"sibling"`
+	}{
+		GrandChild: GrandChild{V: "val"},
+		Sibling:    "joe",
+	},
+}
+
+var embedAnonWithEmbedString = `{"child":{"sibling":"joe","v":"val"}}`