gob: when sending an interface value, indirect down to the

underlying type; otherwise encoding fails when sending
a pointer value.

R=rsc
CC=golang-dev
https://golang.org/cl/2922041

diff --git a/src/pkg/gob/codec_test.go b/src/pkg/gob/codec_test.go
index 426cc80edf3fc5ba69170c153871cb80ceb116a4..a95cfa9929b3492d520c8b707c8cfa92ef3d099d 100644 (file)
--- a/src/pkg/gob/codec_test.go
+++ b/src/pkg/gob/codec_test.go
@@ -1225,7 +1225,6 @@ func TestInterfaceBasic(t *testing.T) {
                "hello",
                []byte("sailor"),
        }
-       // Register the types.
        err := NewEncoder(b).Encode(item1)
        if err != nil {
                t.Error("expected no encode error; got", err)
@@ -1248,6 +1247,44 @@ func TestInterfaceBasic(t *testing.T) {
        }
 }
 
+type String string
+
+type PtrInterfaceItem struct {
+       str interface{} // basic
+       Str interface{} // derived
+}
+
+// We'll send pointers; should receive values.
+// Also check that we can register T but send *T.
+func TestInterfacePointer(t *testing.T) {
+       b := new(bytes.Buffer)
+       str1 := "howdy"
+       str2 := String("kiddo")
+       item1 := &PtrInterfaceItem{
+               &str1,
+               &str2,
+       }
+       // Register the type.
+       Register(str2)
+       err := NewEncoder(b).Encode(item1)
+       if err != nil {
+               t.Error("expected no encode error; got", err)
+       }
+
+       item2 := &PtrInterfaceItem{}
+       err = NewDecoder(b).Decode(&item2)
+       if err != nil {
+               t.Fatal("decode:", err)
+       }
+       // Hand test for correct types and values.
+       if v, ok := item2.str.(string); !ok || v != str1 {
+               t.Errorf("basic string failed: %q should be %q", v, str1)
+       }
+       if v, ok := item2.Str.(String); !ok || v != str2 {
+               t.Errorf("derived type String failed: %q should be %q", v, str2)
+       }
+}
+
 func TestIgnoreInterface(t *testing.T) {
        iVal := Int(3)
        fVal := Float(5)

diff --git a/src/pkg/gob/encode.go b/src/pkg/gob/encode.go
index 694cddbcc90b756b053e65fec64bd21784b52baa..73938668020c0689c4ee679b8c6cd48be24de52c 100644 (file)
--- a/src/pkg/gob/encode.go
+++ b/src/pkg/gob/encode.go
@@ -404,7 +404,7 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
                return
        }
 
-       typ := iv.Elem().Type()
+       typ, _ := indirect(iv.Elem().Type())
        name, ok := concreteTypeToName[typ]
        if !ok {
                errorf("gob: type not registered for interface: %s", typ)