From 30775f67e7d5e897d4d9aafe8ab84a5f65550ce4 Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Fri, 2 Dec 2011 00:02:24 -0800
Subject: [PATCH] encoding/gob: don't send type info for unexported fields
 Fixes #2517.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/5440079
---
 src/pkg/encoding/gob/encoder.go      |  4 +++-
 src/pkg/encoding/gob/encoder_test.go | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/pkg/encoding/gob/encoder.go b/src/pkg/encoding/gob/encoder.go
index e4a48dfc4fc..a15b5a1f9a1 100644
--- a/src/pkg/encoding/gob/encoder.go
+++ b/src/pkg/encoding/gob/encoder.go
@@ -119,7 +119,9 @@ func (enc *Encoder) sendActualType(w io.Writer, state *encoderState, ut *userTyp
 	switch st := actual; st.Kind() {
 	case reflect.Struct:
 		for i := 0; i < st.NumField(); i++ {
-			enc.sendType(w, state, st.Field(i).Type)
+			if isExported(st.Field(i).Name) {
+				enc.sendType(w, state, st.Field(i).Type)
+			}
 		}
 	case reflect.Array, reflect.Slice:
 		enc.sendType(w, state, st.Elem())
diff --git a/src/pkg/encoding/gob/encoder_test.go b/src/pkg/encoding/gob/encoder_test.go
index bc5af120af3..5bc957bb370 100644
--- a/src/pkg/encoding/gob/encoder_test.go
+++ b/src/pkg/encoding/gob/encoder_test.go
@@ -662,3 +662,19 @@ func TestSequentialDecoder(t *testing.T) {
 		}
 	}
 }
+
+// Should be able to have unrepresentable fields (chan, func) as long as they
+// are unexported.
+type Bug2 struct {
+	A int
+	b chan int
+}
+
+func TestUnexportedChan(t *testing.T) {
+	b := Bug2{23, make(chan int)}
+	var stream bytes.Buffer
+	enc := NewEncoder(&stream)
+	if err := enc.Encode(b); err != nil {
+		t.Fatalf("error encoding unexported channel: %s", err)
+	}
+}