From 151b2f15094168946993448f7f4a5e2a8441bd76 Mon Sep 17 00:00:00 2001
From: Luuk van Dijk <lvd@golang.org>
Date: Wed, 9 Nov 2011 11:17:06 +0100
Subject: [PATCH] gc: Fail on implicit assigment to non-exported fields in copy
 and append.

Fixes #1387.

R=rsc
CC=golang-dev
https://golang.org/cl/5348046
---
 src/cmd/gc/typecheck.c   |  5 +++++
 test/fixedbugs/bug378.go | 27 +++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 test/fixedbugs/bug378.go

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index f154db9eb48..f84f8440c4d 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -1032,6 +1032,9 @@ reswitch:
 			yyerror("first argument to append must be slice; have %lT", t);
 			goto error;
 		}
+		if(!exportassignok(t->type, "append"))
+			goto error;
+
 		if(n->isddd) {
 			if(args->next == nil) {
 				yyerror("cannot use ... on first argument to append");
@@ -1098,6 +1101,8 @@ reswitch:
 			yyerror("arguments to copy have different element types: %lT and %lT", n->left->type, n->right->type);
 			goto error;
 		}
+		if(!exportassignok(n->left->type->type, "copy"))
+			goto error;
 		goto ret;
 
 	case OCONV:
diff --git a/test/fixedbugs/bug378.go b/test/fixedbugs/bug378.go
new file mode 100644
index 00000000000..91975f2e931
--- /dev/null
+++ b/test/fixedbugs/bug378.go
@@ -0,0 +1,27 @@
+// errchk $G $D/$F.go
+
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 1387
+package foo
+
+import "bytes"
+
+func i() {
+	a := make([]bytes.Buffer, 1)
+	b := a[0] // ERROR "unexported field"
+}
+
+func f() {
+	a := make([]bytes.Buffer, 1)
+	a = append(a, a...) // ERROR "unexported field"
+}
+
+
+func g() {
+	a := make([]bytes.Buffer, 1)
+	b := make([]bytes.Buffer, 1)
+	copy(b, a)	// ERROR "unexported field"
+}