json: fix []unmarshaler case

Now that reflect has v.Addr(), we can use it.

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/4860041

src/pkg/json/decode.go

@@ -251,6 +251,12 @@ func (d *decodeState) value(v reflect.Value) {
 // if it encounters an Unmarshaler, indirect stops and returns that.
 // if wantptr is true, indirect stops at the last pointer.
 func (d *decodeState) indirect(v reflect.Value, wantptr bool) (Unmarshaler, reflect.Value) {
+	// If v is a named type and is addressable,
+	// start with its address, so that if the type has pointer methods,
+	// we find them.
+	if v.Kind() != reflect.Ptr && v.Type().Name() != "" && v.CanAddr() {
+		v = v.Addr()
+	}
 	for {
 		var isUnmarshaler bool
 		if v.Type().NumMethod() > 0 {

src/pkg/json/decode_test.go

@@ -34,10 +34,17 @@ func (u *unmarshaler) UnmarshalJSON(b []byte) os.Error {
 	return nil
 }
 
+type ustruct struct {
+	M unmarshaler
+}
+
 var (
 	um0, um1 unmarshaler // target2 of unmarshaling
 	ump      = &um1
 	umtrue   = unmarshaler{true}
+	umslice  = []unmarshaler{unmarshaler{true}}
+	umslicep = new([]unmarshaler)
+	umstruct = ustruct{unmarshaler{true}}
 )
 
 type unmarshalTest struct {
@@ -77,6 +84,9 @@ var unmarshalTests = []unmarshalTest{
 	// unmarshal interface test
 	{`{"T":false}`, &um0, umtrue, nil}, // use "false" so test will fail if custom unmarshaler is not called
 	{`{"T":false}`, &ump, &umtrue, nil},
+	{`[{"T":false}]`, &umslice, umslice, nil},
+	{`[{"T":false}]`, &umslicep, &umslice, nil},
+	{`{"M":{"T":false}}`, &umstruct, umstruct, nil},
 }
 
 func TestMarshal(t *testing.T) {
@@ -140,7 +150,6 @@ func TestUnmarshal(t *testing.T) {
 			println(string(data))
 			data, _ = Marshal(tt.out)
 			println(string(data))
-			return
 			continue
 		}
 	}