From a45777fe9975583cac3ef7ee5d61937f5a003c5a Mon Sep 17 00:00:00 2001
From: Daniel Morsing <daniel.morsing@gmail.com>
Date: Sun, 7 Oct 2012 06:53:57 +0200
Subject: [PATCH] cmd/gc: Don't export embedded builtins

Fixes #4124.

R=golang-dev, dave, minux.ma, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/6543057
---
 src/cmd/gc/align.c             |  2 +-
 src/cmd/gc/dcl.c               |  2 +-
 src/cmd/gc/fmt.c               |  2 +-
 src/cmd/gc/lex.c               |  4 ++--
 src/cmd/gc/reflect.c           |  5 ++++-
 test/fixedbugs/bug460.dir/a.go |  9 +++++++++
 test/fixedbugs/bug460.dir/b.go | 14 ++++++++++++++
 test/fixedbugs/bug460.go       | 10 ++++++++++
 test/fixedbugs/bug461.go       | 23 +++++++++++++++++++++++
 9 files changed, 65 insertions(+), 6 deletions(-)
 create mode 100644 test/fixedbugs/bug460.dir/a.go
 create mode 100644 test/fixedbugs/bug460.dir/b.go
 create mode 100644 test/fixedbugs/bug460.go
 create mode 100644 test/fixedbugs/bug461.go

diff --git a/src/cmd/gc/align.c b/src/cmd/gc/align.c
index 36a33d4827..2440a4b3e2 100644
--- a/src/cmd/gc/align.c
+++ b/src/cmd/gc/align.c
@@ -607,7 +607,7 @@ typeinit(void)
 			fatal("typeinit: %s already defined", s->name);
 
 		t = typ(etype);
-		t->sym = s;
+		t->sym = s1;
 
 		dowidth(t);
 		types[etype] = t;
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index 1f50910526..d090380d7e 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -982,7 +982,7 @@ embedded(Sym *s)
 		*utfrune(name, CenterDot) = 0;
 	}
 
-	if(exportname(name) || s->pkg == builtinpkg)  // old behaviour, tests pass, but is it correct?
+	if(exportname(name))
 		n = newname(lookup(name));
 	else
 		n = newname(pkglookup(name, s->pkg));
diff --git a/src/cmd/gc/fmt.c b/src/cmd/gc/fmt.c
index c59d1b9fcd..5a1f679301 100644
--- a/src/cmd/gc/fmt.c
+++ b/src/cmd/gc/fmt.c
@@ -1181,7 +1181,7 @@ exprfmt(Fmt *f, Node *n, int prec)
 					t = l->n->left->type->type;
 					if(t->sym == S)
 						t = t->type;
-					fmtprint(f, " %T:%N", t, l->n->right);
+					fmtprint(f, " %hhS:%N", t->sym, l->n->right);
 				} else
 					fmtprint(f, " %hhS:%N", l->n->left->sym, l->n->right);
 
diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index 6bf00161b7..46728c904d 100644
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -1831,16 +1831,16 @@ lexinit(void)
 		if(etype != Txxx) {
 			if(etype < 0 || etype >= nelem(types))
 				fatal("lexinit: %s bad etype", s->name);
+			s1 = pkglookup(syms[i].name, builtinpkg);
 			t = types[etype];
 			if(t == T) {
 				t = typ(etype);
-				t->sym = s;
+				t->sym = s1;
 
 				if(etype != TANY && etype != TSTRING)
 					dowidth(t);
 				types[etype] = t;
 			}
-			s1 = pkglookup(syms[i].name, builtinpkg);
 			s1->lexical = LNAME;
 			s1->def = typenod(t);
 			continue;
diff --git a/src/cmd/gc/reflect.c b/src/cmd/gc/reflect.c
index ad1d8d8606..8e4f0a4d27 100644
--- a/src/cmd/gc/reflect.c
+++ b/src/cmd/gc/reflect.c
@@ -866,7 +866,10 @@ ok:
 					ot = dgopkgpath(s, ot, t1->sym->pkg);
 			} else {
 				ot = dgostringptr(s, ot, nil);
-				ot = dgostringptr(s, ot, nil);
+				if(t1->type->sym != S && t1->type->sym->pkg == builtinpkg)
+					ot = dgopkgpath(s, ot, localpkg);
+				else
+					ot = dgostringptr(s, ot, nil);
 			}
 			ot = dsymptr(s, ot, dtypesym(t1->type), 0);
 			ot = dgostrlitptr(s, ot, t1->note);
diff --git a/test/fixedbugs/bug460.dir/a.go b/test/fixedbugs/bug460.dir/a.go
new file mode 100644
index 0000000000..02a287b317
--- /dev/null
+++ b/test/fixedbugs/bug460.dir/a.go
@@ -0,0 +1,9 @@
+// Copyright 2012 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.
+
+package a
+
+type Foo struct {
+	int
+}
diff --git a/test/fixedbugs/bug460.dir/b.go b/test/fixedbugs/bug460.dir/b.go
new file mode 100644
index 0000000000..1868afe073
--- /dev/null
+++ b/test/fixedbugs/bug460.dir/b.go
@@ -0,0 +1,14 @@
+// Copyright 2012 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.
+
+package b
+
+import "./a"
+
+var x a.Foo
+
+func main() {
+	x.int = 20 // ERROR "unexported field"
+}
+
diff --git a/test/fixedbugs/bug460.go b/test/fixedbugs/bug460.go
new file mode 100644
index 0000000000..79234a3b96
--- /dev/null
+++ b/test/fixedbugs/bug460.go
@@ -0,0 +1,10 @@
+// errorcheckdir
+
+// Copyright 2012 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.
+
+// part one of issue 4124. Make sure that the compiler rejects access attempts.
+
+package ignored
+
diff --git a/test/fixedbugs/bug461.go b/test/fixedbugs/bug461.go
new file mode 100644
index 0000000000..f0f7b0e69b
--- /dev/null
+++ b/test/fixedbugs/bug461.go
@@ -0,0 +1,23 @@
+// run
+
+// Copyright 2012 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.
+
+// part two of issue 4124. Make sure reflect doesn't mark the field as exported.
+
+package main
+
+import "reflect"
+
+var T struct {
+	int
+}
+
+func main() {
+	v := reflect.ValueOf(&T)
+	v = v.Elem().Field(0)
+	if v.CanSet() {
+		panic("int should be unexported")
+	}
+}
-- 
2.48.1