Fix size of oneof fields when they are set to their zero value.

We use the proto3 sizers for oneof fields (because they don't have
a pointer in the wrapper struct), but they are always encoded when set,
so we should not skip their zero value.

Fixes #74.

proto/encode.go

@@ -332,7 +332,7 @@ func size_bool(p *Properties, base structPointer) int {
 
 func size_proto3_bool(p *Properties, base structPointer) int {
 	v := *structPointer_BoolVal(base, p.field)
-	if !v {
+	if !v && !p.oneof {
 		return 0
 	}
 	return len(p.tagcode) + 1 // each bool takes exactly one byte
@@ -375,7 +375,7 @@ func size_int32(p *Properties, base structPointer) (n int) {
 func size_proto3_int32(p *Properties, base structPointer) (n int) {
 	v := structPointer_Word32Val(base, p.field)
 	x := int32(word32Val_Get(v)) // permit sign extension to use full 64-bit range
-	if x == 0 {
+	if x == 0 && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)
@@ -421,7 +421,7 @@ func size_uint32(p *Properties, base structPointer) (n int) {
 func size_proto3_uint32(p *Properties, base structPointer) (n int) {
 	v := structPointer_Word32Val(base, p.field)
 	x := word32Val_Get(v)
-	if x == 0 {
+	if x == 0 && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)
@@ -466,7 +466,7 @@ func size_int64(p *Properties, base structPointer) (n int) {
 func size_proto3_int64(p *Properties, base structPointer) (n int) {
 	v := structPointer_Word64Val(base, p.field)
 	x := word64Val_Get(v)
-	if x == 0 {
+	if x == 0 && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)
@@ -509,7 +509,7 @@ func size_string(p *Properties, base structPointer) (n int) {
 
 func size_proto3_string(p *Properties, base structPointer) (n int) {
 	v := *structPointer_StringVal(base, p.field)
-	if v == "" {
+	if v == "" && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)
@@ -681,7 +681,7 @@ func (o *Buffer) enc_proto3_slice_byte(p *Properties, base structPointer) error
 
 func size_slice_byte(p *Properties, base structPointer) (n int) {
 	s := *structPointer_Bytes(base, p.field)
-	if s == nil {
+	if s == nil && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)
@@ -691,7 +691,7 @@ func size_slice_byte(p *Properties, base structPointer) (n int) {
 
 func size_proto3_slice_byte(p *Properties, base structPointer) (n int) {
 	s := *structPointer_Bytes(base, p.field)
-	if len(s) == 0 {
+	if len(s) == 0 && !p.oneof {
 		return 0
 	}
 	n += len(p.tagcode)

proto/properties.go

@@ -177,6 +177,7 @@ type Properties struct {
 	Packed   bool   // relevant for repeated primitives only
 	Enum     string // set for enum types only
 	proto3   bool   // whether this is known to be a proto3 field; set for []byte only
+	oneof    bool   // whether this is a oneof field
 
 	Default    string // default value
 	HasDefault bool   // whether an explicit default was provided
@@ -229,6 +230,9 @@ func (p *Properties) String() string {
 	if p.proto3 {
 		s += ",proto3"
 	}
+	if p.oneof {
+		s += ",oneof"
+	}
 	if len(p.Enum) > 0 {
 		s += ",enum=" + p.Enum
 	}
@@ -305,6 +309,8 @@ func (p *Properties) Parse(s string) {
 			p.Enum = f[5:]
 		case f == "proto3":
 			p.proto3 = true
+		case f == "oneof":
+			p.oneof = true
 		case strings.HasPrefix(f, "def="):
 			p.HasDefault = true
 			p.Default = f[4:] // rest of string

proto/size_test.go

@@ -126,6 +126,7 @@ var SizeTests = []struct {
 	{"map field with big numeric key", &pb.MessageWithMap{NameMapping: map[int32]string{0xf00d: "om nom nom"}}},
 
 	{"oneof not set", &pb.Communique{}},
+	{"oneof zero int32", &pb.Communique{Union: &pb.Communique_Number{0}}},
 	{"oneof int32", &pb.Communique{Union: &pb.Communique_Number{3}}},
 	{"oneof string", &pb.Communique{Union: &pb.Communique_Name{"Rhythmic Fman"}}},
 }

protoc-gen-go/generator/generator.go

@@ -303,7 +303,7 @@ type getterSymbol struct {
 	name     string
 	typ      string
 	typeName string // canonical name in proto world; empty for proto.Message and similar
-	genType  bool   // whether typ is a generated type (message/group/enum)
+	genType  bool   // whether typ contains a generated type (message/group/enum)
 }
 
 func (ms *messageSymbol) GenerateAlias(g *Generator, pkg string) {
@@ -333,15 +333,19 @@ func (ms *messageSymbol) GenerateAlias(g *Generator, pkg string) {
 		typ := get.typ
 		val := "(*" + remoteSym + ")(m)." + get.name + "()"
 		if get.genType {
-			// typ will be "*pkg.T" (message/group) or "pkg.T" (enum).
-			// Either of those might have a "[]" prefix if it is repeated.
-			// Drop the package qualifier since we have hoisted the type into this package.
+			// typ will be "*pkg.T" (message/group) or "pkg.T" (enum)
+			// or "map[t]*pkg.T" (map to message/enum).
+			// The first two of those might have a "[]" prefix if it is repeated.
+			// Drop any package qualifier since we have hoisted the type into this package.
 			rep := strings.HasPrefix(typ, "[]")
 			if rep {
 				typ = typ[2:]
 			}
+			isMap := strings.HasPrefix(typ, "map[")
 			star := typ[0] == '*'
-			typ = typ[strings.Index(typ, ".")+1:]
+			if !isMap { // map types handled lower down
+				typ = typ[strings.Index(typ, ".")+1:]
+			}
 			if star {
 				typ = "*" + typ
 			}
@@ -376,6 +380,30 @@ func (ms *messageSymbol) GenerateAlias(g *Generator, pkg string) {
 				g.P("}")
 				continue
 			}
+			if isMap {
+				// Split map[keyTyp]valTyp.
+				bra, ket := strings.Index(typ, "["), strings.Index(typ, "]")
+				keyTyp, valTyp := typ[bra+1:ket], typ[ket+1:]
+				// Drop any package qualifier.
+				// Only the value type may be foreign.
+				star := valTyp[0] == '*'
+				valTyp = valTyp[strings.Index(valTyp, ".")+1:]
+				if star {
+					valTyp = "*" + valTyp
+				}
+
+				typ := "map[" + keyTyp + "]" + valTyp
+				g.P("func (m *", ms.sym, ") ", get.name, "() ", typ, " {")
+				g.P("o := ", val)
+				g.P("if o == nil { return nil }")
+				g.P("s := make(", typ, ", len(o))")
+				g.P("for k, v := range o {")
+				g.P("s[k] = (", valTyp, ")(v)")
+				g.P("}")
+				g.P("return s")
+				g.P("}")
+				continue
+			}
 			// Convert imported type into the forwarding type.
 			val = "(" + typ + ")(" + val + ")"
 		}
@@ -863,6 +891,9 @@ func wrapImported(file *descriptor.FileDescriptorProto, g *Generator) (sl []*Imp
 	for _, index := range file.PublicDependency {
 		df := g.fileByName(file.Dependency[index])
 		for _, d := range df.desc {
+			if d.GetOptions().GetMapEntry() {
+				continue
+			}
 			sl = append(sl, &ImportedDescriptor{common{file}, d})
 		}
 		for _, e := range df.enum {
@@ -1433,13 +1464,18 @@ func (g *Generator) goTag(message *Descriptor, field *descriptor.FieldDescriptor
 			name += ",proto3"
 		}
 	}
-	return strconv.Quote(fmt.Sprintf("%s,%d,%s%s%s%s%s",
+	oneof := ""
+	if field.OneofIndex != nil {
+		oneof = ",oneof"
+	}
+	return strconv.Quote(fmt.Sprintf("%s,%d,%s%s%s%s%s%s",
 		wiretype,
 		field.GetNumber(),
 		optrepreq,
 		packed,
 		name,
 		enum,
+		oneof,
 		defaultValue))
 }
 

protoc-gen-go/testdata/imp.proto

@@ -48,6 +48,8 @@ message ImportedMessage {
   repeated Owner boss = 6;
   repeated ImportedMessage2 memo = 7;
 
+  map<string, ImportedMessage2> msg_map = 8;
+
   enum Owner {
     DAVE = 1;
     MIKE = 2;