more gob bugs

1) need to send slice and array types (was only sending element types)
2) compatibleType needs to use decoder's type map

R=rsc
CC=golang-dev
https://golang.org/cl/164062

src/pkg/gob/decode.go

@@ -527,7 +527,12 @@ func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp
 				op = decUint8Array;
 				break;
 			}
-			elemId := wireId.gobType().(*sliceType).Elem;
+			var elemId typeId;
+			if tt, ok := builtinIdToType[wireId]; ok {
+				elemId = tt.(*sliceType).Elem
+			} else {
+				elemId = dec.wireType[wireId].slice.Elem
+			}
 			elemOp, elemIndir, err := dec.decOpFor(elemId, t.Elem(), name);
 			if err != nil {
 				return nil, 0, err
@@ -614,7 +619,7 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
 // Are these two gob Types compatible?
 // Answers the question for basic types, arrays, and slices.
 // Structs are considered ok; fields will be checked later.
-func compatibleType(fr reflect.Type, fw typeId) bool {
+func (dec *Decoder) compatibleType(fr reflect.Type, fw typeId) bool {
 	for {
 		if pt, ok := fr.(*reflect.PtrType); ok {
 			fr = pt.Elem();
@@ -660,16 +665,22 @@ func compatibleType(fr reflect.Type, fw typeId) bool {
 		return fw == tString
 	case *reflect.ArrayType:
 		aw, ok := fw.gobType().(*arrayType);
-		return ok && t.Len() == aw.Len && compatibleType(t.Elem(), aw.Elem);
+		return ok && t.Len() == aw.Len && dec.compatibleType(t.Elem(), aw.Elem);
 	case *reflect.SliceType:
 		// Is it an array of bytes?
 		et := t.Elem();
 		if _, ok := et.(*reflect.Uint8Type); ok {
 			return fw == tBytes
 		}
-		sw, ok := fw.gobType().(*sliceType);
+		// Extract and compare element types.
+		var sw *sliceType;
+		if tt, ok := builtinIdToType[fw]; ok {
+			sw = tt.(*sliceType)
+		} else {
+			sw = dec.wireType[fw].slice
+		}
 		elem, _ := indirect(t.Elem());
-		return ok && compatibleType(elem, sw.Elem);
+		return sw != nil && dec.compatibleType(elem, sw.Elem);
 	case *reflect.StructType:
 		return true
 	}
@@ -687,7 +698,7 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
 		if !ok1 || !ok2 {
 			return nil, errNotStruct
 		}
-		wireStruct = w.s;
+		wireStruct = w.strct;
 	}
 	engine = new(decEngine);
 	engine.instr = make([]decInstr, len(wireStruct.field));
@@ -706,7 +717,7 @@ func (dec *Decoder) compileDec(remoteId typeId, rt reflect.Type) (engine *decEng
 			engine.instr[fieldnum] = decInstr{op, fieldnum, 0, 0, ovfl};
 			continue;
 		}
-		if !compatibleType(localField.Type, wireField.id) {
+		if !dec.compatibleType(localField.Type, wireField.id) {
 			details := " (" + wireField.id.String() + " incompatible with " + localField.Type.String() + ") in type " + remoteId.Name();
 			return nil, os.ErrorString("gob: wrong type for field " + wireField.name + details);
 		}

src/pkg/gob/encoder.go

@@ -244,17 +244,20 @@ func (enc *Encoder) sendType(origt reflect.Type) {
 	default:
 		// Basic types do not need to be described.
 		return
+	case reflect.ArrayOrSliceType:
+		// If it's []uint8, don't send; it's considered basic.
+		if _, ok := rt.Elem().(*reflect.Uint8Type); ok {
+			return
+		}
+		// Otherwise we do send.
+		break;
+	// Struct types are not sent, only their element types.
 	case *reflect.StructType:
-		// Structs do need to be described.
 		break
 	case *reflect.ChanType, *reflect.FuncType, *reflect.MapType, *reflect.InterfaceType:
 		// Probably a bad field in a struct.
 		enc.badType(rt);
 		return;
-	// Array and slice types are not sent, only their element types.
-	case reflect.ArrayOrSliceType:
-		enc.sendType(rt.Elem());
-		return;
 	}
 
 	// Have we already sent this type?  This time we ask about the base type.
@@ -282,9 +285,13 @@ func (enc *Encoder) sendType(origt reflect.Type) {
 	// Remember we've sent the top-level, possibly indirect type too.
 	enc.sent[origt] = info.id;
 	// Now send the inner types
-	st := rt.(*reflect.StructType);
-	for i := 0; i < st.NumField(); i++ {
-		enc.sendType(st.Field(i).Type)
+	switch st := rt.(type) {
+	case *reflect.StructType:
+		for i := 0; i < st.NumField(); i++ {
+			enc.sendType(st.Field(i).Type)
+		}
+	case reflect.ArrayOrSliceType:
+		enc.sendType(st.Elem())
 	}
 	return;
 }

src/pkg/gob/encoder_test.go

@@ -213,3 +213,15 @@ func TestTypeToPtrPtrPtrPtrType(t *testing.T) {
 		t.Errorf("wrong value after decode: %g not %g", ****(****t2pppp).a, ****t2.a)
 	}
 }
+
+func TestSlice(t *testing.T) {
+	// Encode a *T, decode a T
+	type Type3 struct {
+		a []string;
+	}
+	t3p := &Type3{[]string{"hello", "world"}};
+	var t3 Type3;
+	if err := encAndDec(t3, t3p); err != nil {
+		t.Error(err)
+	}
+}

src/pkg/gob/type.go

@@ -98,13 +98,13 @@ var tBytes = bootstrapType("bytes", make([]byte, 0), 5)
 var tString = bootstrapType("string", "", 6)
 
 // Predefined because it's needed by the Decoder
-var tWireType = getTypeInfoNoError(reflect.Typeof(wireType{})).id
+var tWireType = mustGetTypeInfo(reflect.Typeof(wireType{})).id
 
 func init() {
 	checkId(7, tWireType);
-	checkId(8, getTypeInfoNoError(reflect.Typeof(structType{})).id);
-	checkId(9, getTypeInfoNoError(reflect.Typeof(commonType{})).id);
-	checkId(10, getTypeInfoNoError(reflect.Typeof(fieldType{})).id);
+	checkId(9, mustGetTypeInfo(reflect.Typeof(commonType{})).id);
+	checkId(11, mustGetTypeInfo(reflect.Typeof(structType{})).id);
+	checkId(12, mustGetTypeInfo(reflect.Typeof(fieldType{})).id);
 	builtinIdToType = make(map[typeId]gobType);
 	for k, v := range idToType {
 		builtinIdToType[k] = v
@@ -346,12 +346,16 @@ func bootstrapType(name string, e interface{}, expect typeId) typeId {
 // are built in encode.go's init() function.
 
 type wireType struct {
-	s *structType;
+	array	*arrayType;
+	slice	*sliceType;
+	strct	*structType;
 }
 
 func (w *wireType) name() string {
-	// generalize once we can have non-struct types on the wire.
-	return w.s.name
+	if w.strct != nil {
+		return w.strct.name
+	}
+	return "unknown";
 }
 
 type typeInfo struct {
@@ -377,15 +381,25 @@ func getTypeInfo(rt reflect.Type) (*typeInfo, os.Error) {
 			return nil, err
 		}
 		info.id = gt.id();
-		// assume it's a struct type
-		info.wire = &wireType{info.id.gobType().(*structType)};
+		t := info.id.gobType();
+		switch typ := rt.(type) {
+		case *reflect.ArrayType:
+			info.wire = &wireType{array: t.(*arrayType)}
+		case *reflect.SliceType:
+			// []byte == []uint8 is a special case handled separately
+			if _, ok := typ.Elem().(*reflect.Uint8Type); !ok {
+				info.wire = &wireType{slice: t.(*sliceType)}
+			}
+		case *reflect.StructType:
+			info.wire = &wireType{strct: t.(*structType)}
+		}
 		typeInfoMap[rt] = info;
 	}
 	return info, nil;
 }
 
 // Called only when a panic is acceptable and unexpected.
-func getTypeInfoNoError(rt reflect.Type) *typeInfo {
+func mustGetTypeInfo(rt reflect.Type) *typeInfo {
 	t, err := getTypeInfo(rt);
 	if err != nil {
 		panicln("getTypeInfo:", err.String())