gob: don't send type information about unexported fields.

A change a while back stop sending data for unexported fields
but due to an oversight the type info was being sent also. It's
inconsequential but wrong to do that.

R=rsc, rh
CC=golang-dev
https://golang.org/cl/4252058

src/pkg/gob/decode.go

@@ -13,9 +13,7 @@ import (
 	"math"
 	"os"
 	"reflect"
-	"unicode"
 	"unsafe"
-	"utf8"
 )
 
 var (
@@ -1073,12 +1071,6 @@ func (dec *Decoder) compileIgnoreSingle(remoteId typeId) (engine *decEngine, err
 	return
 }
 
-// isExported reports whether this is an exported - upper case - name.
-func isExported(name string) bool {
-	rune, _ := utf8.DecodeRuneInString(name)
-	return unicode.IsUpper(rune)
-}
-
 // compileDec compiles the decoder engine for a value.  If the value is not a struct,
 // it calls out to compileSingle.
 func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEngine, err os.Error) {

src/pkg/gob/encode.go

@@ -606,13 +606,14 @@ func (enc *Encoder) compileEnc(ut *userTypeInfo) *encEngine {
 		rt = ut.user
 	}
 	if !ut.isGobEncoder && isStruct {
-		for fieldNum := 0; fieldNum < srt.NumField(); fieldNum++ {
+		for fieldNum, wireFieldNum := 0, 0; fieldNum < srt.NumField(); fieldNum++ {
 			f := srt.Field(fieldNum)
 			if !isExported(f.Name) {
 				continue
 			}
 			op, indir := enc.encOpFor(f.Type, seen)
-			engine.instr = append(engine.instr, encInstr{*op, fieldNum, indir, uintptr(f.Offset)})
+			engine.instr = append(engine.instr, encInstr{*op, wireFieldNum, indir, uintptr(f.Offset)})
+			wireFieldNum++
 		}
 		if srt.NumField() > 0 && len(engine.instr) == 0 {
 			errorf("type %s has no exported fields", rt)

src/pkg/gob/type.go

@@ -9,6 +9,8 @@ import (
 	"os"
 	"reflect"
 	"sync"
+	"unicode"
+	"utf8"
 )
 
 // userTypeInfo stores the information associated with a type the user has handed
@@ -418,10 +420,6 @@ func newStructType(name string) *structType {
 	return s
 }
 
-func (s *structType) init(field []*fieldType) {
-	s.Field = field
-}
-
 // newTypeObject allocates a gobType for the reflection type rt.
 // Unless ut represents a GobEncoder, rt should be the base type
 // of ut.
@@ -514,10 +512,11 @@ func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, os.
 		st := newStructType(name)
 		types[rt] = st
 		idToType[st.id()] = st
-		field := make([]*fieldType, t.NumField())
 		for i := 0; i < t.NumField(); i++ {
-			// TODO: don't send unexported fields.
 			f := t.Field(i)
+			if !isExported(f.Name) {
+				continue
+			}
 			typ := userType(f.Type).base
 			tname := typ.Name()
 			if tname == "" {
@@ -528,9 +527,8 @@ func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, os.
 			if err != nil {
 				return nil, err
 			}
-			field[i] = &fieldType{f.Name, gt.id()}
+			st.Field = append(st.Field, &fieldType{f.Name, gt.id()})
 		}
-		st.init(field)
 		return st, nil
 
 	default:
@@ -539,6 +537,12 @@ func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, os.
 	return nil, nil
 }
 
+// isExported reports whether this is an exported - upper case - name.
+func isExported(name string) bool {
+	rune, _ := utf8.DecodeRuneInString(name)
+	return unicode.IsUpper(rune)
+}
+
 // getBaseType returns the Gob type describing the given reflect.Type's base type.
 // typeLock must be held.
 func getBaseType(name string, rt reflect.Type) (gobType, os.Error) {

src/pkg/gob/type_test.go

@@ -126,27 +126,27 @@ func TestMapType(t *testing.T) {
 }
 
 type Bar struct {
-	x string
+	X string
 }
 
 // This structure has pointers and refers to itself, making it a good test case.
 type Foo struct {
-	a int
-	b int32 // will become int
-	c string
-	d []byte
-	e *float64    // will become float64
-	f ****float64 // will become float64
-	g *Bar
-	h *Bar // should not interpolate the definition of Bar again
-	i *Foo // will not explode
+	A int
+	B int32 // will become int
+	C string
+	D []byte
+	E *float64    // will become float64
+	F ****float64 // will become float64
+	G *Bar
+	H *Bar // should not interpolate the definition of Bar again
+	I *Foo // will not explode
 }
 
 func TestStructType(t *testing.T) {
 	sstruct := getTypeUnlocked("Foo", reflect.Typeof(Foo{}))
 	str := sstruct.string()
 	// If we can print it correctly, we built it correctly.
-	expected := "Foo = struct { a int; b int; c string; d bytes; e float; f float; g Bar = struct { x string; }; h Bar; i Foo; }"
+	expected := "Foo = struct { A int; B int; C string; D bytes; E float; F float; G Bar = struct { X string; }; H Bar; I Foo; }"
 	if str != expected {
 		t.Errorf("struct printed as %q; expected %q", str, expected)
 	}