diff --git a/doc/go_spec.html b/doc/go_spec.html
index e397d0aea03..0e52d4d230c 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -1,5 +1,5 @@
 <!-- title The Go Programming Language Specification -->
-<!-- subtitle Version of November 13, 2011 -->
+<!-- subtitle Version of November 14, 2011 -->
 
 <!--
 TODO
@@ -1367,15 +1367,6 @@ by a value of type <code>T</code>.
 </li>
 </ul>
 
-<p>
-If <code>T</code> is a struct type with non-<a href="#Exported_identifiers">exported</a>
-fields, the assignment must be in the same package in which <code>T</code> is declared,
-or <code>x</code> must be the receiver of a method call.
-In other words, a struct value can be assigned to a struct variable only if
-every field of the struct may be legally assigned individually by the program,
-or if the assignment is initializing the receiver of a method of the struct type.
-</p>
-
 <p>
 Any value may be assigned to the <a href="#Blank_identifier">blank identifier</a>.
 </p>
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index e21620f4553..a473c2fb504 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -1234,7 +1234,6 @@ void	walkswitch(Node *sw);
 /*
  *	typecheck.c
  */
-int	exportassignok(Type *t, char *desc);
 int	islvalue(Node *n);
 Node*	typecheck(Node **np, int top);
 void	typechecklist(NodeList *l, int top);
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 0df34c1a4fb..913ea22d304 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -1018,9 +1018,6 @@ eqtypenoname(Type *t1, Type *t2)
 // Is type src assignment compatible to type dst?
 // If so, return op code to use in conversion.
 // If not, return 0.
-//
-// It is the caller's responsibility to call exportassignok
-// to check for assignments to other packages' unexported fields,
 int
 assignop(Type *src, Type *dst, char **why)
 {
@@ -1225,7 +1222,6 @@ assignconv(Node *n, Type *t, char *context)
 	if(t->etype == TBLANK)
 		return n;
 
-	exportassignok(n->type, context);
 	if(eqtype(n->type, t))
 		return n;
 
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index aaf836f8239..5b667553fa2 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -1045,8 +1045,6 @@ 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) {
@@ -1114,8 +1112,6 @@ 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:
@@ -1731,7 +1727,6 @@ typecheckaste(int op, Node *call, int isddd, Type *tstruct, NodeList *nl, char *
 		for(tl=tstruct->type; tl; tl=tl->down) {
 			if(tl->isddd) {
 				for(; tn; tn=tn->down) {
-					exportassignok(tn->type, desc);
 					if(assignop(tn->type, tl->type->type, &why) == 0) {
 						if(call != N)
 							yyerror("cannot use %T as type %T in argument to %N%s", tn->type, tl->type, call, why);
@@ -1743,7 +1738,6 @@ typecheckaste(int op, Node *call, int isddd, Type *tstruct, NodeList *nl, char *
 			}
 			if(tn == T)
 				goto notenough;
-			exportassignok(tn->type, desc);
 			if(assignop(tn->type, tl->type, &why) == 0) {
 				if(call != N)
 					yyerror("cannot use %T as type %T in argument to %N%s", tn->type, tl->type, call, why);
@@ -1815,66 +1809,6 @@ toomany:
 	goto out;
 }
 
-/*
- * do the export rules allow writing to this type?
- * cannot be implicitly assigning to any type with
- * an unavailable field.
- */
-int
-exportassignok(Type *t, char *desc)
-{
-	Type *f;
-	Sym *s;
-
-	if(t == T)
-		return 1;
-	if(t->trecur)
-		return 1;
-	t->trecur = 1;
-
-	switch(t->etype) {
-	default:
-		// most types can't contain others; they're all fine.
-		break;
-	case TSTRUCT:
-		for(f=t->type; f; f=f->down) {
-			if(f->etype != TFIELD)
-				fatal("structas: not field");
-			s = f->sym;
-			// s == nil doesn't happen for embedded fields (they get the type symbol).
-			// it only happens for fields in a ... struct.
-			if(s != nil && !exportname(s->name) && s->pkg != localpkg) {
-				char *prefix;
-
-				prefix = "";
-				if(desc != nil)
-					prefix = " in ";
-				else
-					desc = "";
-				yyerror("implicit assignment of unexported field '%s' of %T%s%s", s->name, t, prefix, desc);
-				goto no;
-			}
-			if(!exportassignok(f->type, desc))
-				goto no;
-		}
-		break;
-
-	case TARRAY:
-		if(t->bound < 0)	// slices are pointers; that's fine
-			break;
-		if(!exportassignok(t->type, desc))
-			goto no;
-		break;
-	}
-	t->trecur = 0;
-	return 1;
-
-no:
-	t->trecur = 0;
-	return 0;
-}
-
-
 /*
  * type check composite
  */
@@ -2310,8 +2244,6 @@ typecheckas(Node *n)
 	if(n->right && n->right->type != T) {
 		if(n->left->type != T)
 			n->right = assignconv(n->right, n->left->type, "assignment");
-		else if(!isblank(n->left))
-			exportassignok(n->right->type, "assignment");
 	}
 	if(n->left->defn == n && n->left->ntype == N) {
 		defaultlit(&n->right, T);
@@ -2335,7 +2267,6 @@ checkassignto(Type *src, Node *dst)
 		yyerror("cannot assign %T to %lN in multiple assignment%s", src, dst, why);
 		return;
 	}
-	exportassignok(dst->type, "multiple assignment");
 }
 
 static void
diff --git a/src/pkg/os/file_plan9.go b/src/pkg/os/file_plan9.go
index 15d66813a20..fc64301484c 100644
--- a/src/pkg/os/file_plan9.go
+++ b/src/pkg/os/file_plan9.go
@@ -11,6 +11,14 @@ import (
 
 // File represents an open file descriptor.
 type File struct {
+	*file
+}
+
+// file is the real representation of *File.
+// The extra level of indirection ensures that no clients of os
+// can overwrite this data, which could cause the finalizer
+// to close the wrong file descriptor.
+type file struct {
 	fd      int
 	name    string
 	dirinfo *dirInfo // nil unless directory being read
@@ -29,8 +37,8 @@ func NewFile(fd int, name string) *File {
 	if fd < 0 {
 		return nil
 	}
-	f := &File{fd: fd, name: name}
-	runtime.SetFinalizer(f, (*File).Close)
+	f := &File{&file{fd: fd, name: name}}
+	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }
 
@@ -110,6 +118,10 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 // Close closes the File, rendering it unusable for I/O.
 // It returns an error, if any.
 func (file *File) Close() error {
+	return file.file.close()
+}
+
+func (file *file) close() error {
 	if file == nil || file.fd < 0 {
 		return Ebadfd
 	}
diff --git a/src/pkg/os/file_unix.go b/src/pkg/os/file_unix.go
index d8fcb22ae1b..f3e0d1f9bec 100644
--- a/src/pkg/os/file_unix.go
+++ b/src/pkg/os/file_unix.go
@@ -13,6 +13,14 @@ import (
 
 // File represents an open file descriptor.
 type File struct {
+	*file
+}
+
+// file is the real representation of *File.
+// The extra level of indirection ensures that no clients of os
+// can overwrite this data, which could cause the finalizer
+// to close the wrong file descriptor.
+type file struct {
 	fd      int
 	name    string
 	dirinfo *dirInfo // nil unless directory being read
@@ -32,8 +40,8 @@ func NewFile(fd int, name string) *File {
 	if fd < 0 {
 		return nil
 	}
-	f := &File{fd: fd, name: name}
-	runtime.SetFinalizer(f, (*File).Close)
+	f := &File{&file{fd: fd, name: name}}
+	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }
 
@@ -71,6 +79,10 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 // Close closes the File, rendering it unusable for I/O.
 // It returns an error, if any.
 func (file *File) Close() error {
+	return file.file.close()
+}
+
+func (file *file) close() error {
 	if file == nil || file.fd < 0 {
 		return EINVAL
 	}
diff --git a/src/pkg/os/file_windows.go b/src/pkg/os/file_windows.go
index fef868c68e6..5b098880f4c 100644
--- a/src/pkg/os/file_windows.go
+++ b/src/pkg/os/file_windows.go
@@ -13,6 +13,14 @@ import (
 
 // File represents an open file descriptor.
 type File struct {
+	*file
+}
+
+// file is the real representation of *File.
+// The extra level of indirection ensures that no clients of os
+// can overwrite this data, which could cause the finalizer
+// to close the wrong file descriptor.
+type file struct {
 	fd      syscall.Handle
 	name    string
 	dirinfo *dirInfo   // nil unless directory being read
@@ -33,8 +41,8 @@ func NewFile(fd syscall.Handle, name string) *File {
 	if fd < 0 {
 		return nil
 	}
-	f := &File{fd: fd, name: name}
-	runtime.SetFinalizer(f, (*File).Close)
+	f := &File{&file{fd: fd, name: name}}
+	runtime.SetFinalizer(f.file, (*file).close)
 	return f
 }
 
@@ -99,6 +107,10 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 // Close closes the File, rendering it unusable for I/O.
 // It returns an error, if any.
 func (file *File) Close() error {
+	return file.file.close()
+}
+
+func (file *file) close() error {
 	if file == nil || file.fd < 0 {
 		return EINVAL
 	}
diff --git a/src/pkg/sync/mutex.go b/src/pkg/sync/mutex.go
index 2d46c89948f..4fc02743c6e 100644
--- a/src/pkg/sync/mutex.go
+++ b/src/pkg/sync/mutex.go
@@ -6,6 +6,8 @@
 // exclusion locks.  Other than the Once and WaitGroup types, most are intended
 // for use by low-level library routines.  Higher-level synchronization is
 // better done via channels and communication.
+//
+// Values containing the types defined in this package should not be copied.
 package sync
 
 import (
diff --git a/test/assign.go b/test/assign.go
index 59471388c06..2192f9ede08 100644
--- a/test/assign.go
+++ b/test/assign.go
@@ -16,38 +16,38 @@ type T struct {
 func main() {
 	{
 		var x, y sync.Mutex
-		x = y	// ERROR "assignment.*Mutex"
+		x = y // ok
 		_ = x
 	}
 	{
 		var x, y T
-		x = y	// ERROR "assignment.*Mutex"
+		x = y // ok
 		_ = x
 	}
 	{
 		var x, y [2]sync.Mutex
-		x = y	// ERROR "assignment.*Mutex"
+		x = y // ok
 		_ = x
 	}
 	{
 		var x, y [2]T
-		x = y	// ERROR "assignment.*Mutex"
+		x = y // ok
 		_ = x
 	}
 	{
-		x := sync.Mutex{0, 0}	// ERROR "assignment.*Mutex"
+		x := sync.Mutex{0, 0} // ERROR "assignment.*Mutex"
 		_ = x
 	}
 	{
-		x := sync.Mutex{key: 0}	// ERROR "(unknown|assignment).*Mutex"
+		x := sync.Mutex{key: 0} // ERROR "(unknown|assignment).*Mutex"
 		_ = x
 	}
 	{
-		x := &sync.Mutex{}	// ok
-		var y sync.Mutex	// ok
-		y = *x	// ERROR "assignment.*Mutex"
-		*x = y	// ERROR "assignment.*Mutex"
+		x := &sync.Mutex{} // ok
+		var y sync.Mutex   // ok
+		y = *x             // ok
+		*x = y             // ok
 		_ = x
 		_ = y
-	}		
+	}
 }
diff --git a/test/fixedbugs/bug226.dir/x.go b/test/fixedbugs/bug226.dir/x.go
deleted file mode 100644
index 64d7a29e7e1..00000000000
--- a/test/fixedbugs/bug226.dir/x.go
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright 2009 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 x
-
-type T struct { x, Y int }
-
-func (t T) M()
diff --git a/test/fixedbugs/bug226.dir/y.go b/test/fixedbugs/bug226.dir/y.go
deleted file mode 100644
index c66d592b7c0..00000000000
--- a/test/fixedbugs/bug226.dir/y.go
+++ /dev/null
@@ -1,31 +0,0 @@
-// Copyright 2009 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 y
-
-import "./x"
-
-func f() {
-	ok := new(x.T);
-	var ok1 x.T;
-	ok2 := &ok1;
-	ok3 := &x.T{};
-	ok4 := &x.T{Y:2};
-	_ = x.T{};
-	_ = x.T{Y:2};
-	
-	ok1.M();
-	bad1 := *ok;	// ERROR "assignment.*T"
-	bad2 := ok1;	// ERROR "assignment.*T"
-	*ok4 = ok1;	// ERROR "assignment.*T"
-	*ok4 = *ok2;	// ERROR "assignment.*T"
-	ok1 = *ok4;	// ERROR "assignment.*T"
-	_ = bad1;
-	_ = bad2;
-	_ = ok4;
-	_ = ok3;
-	_ = ok2;
-	_ = ok1;
-	_ = ok;
-}
diff --git a/test/fixedbugs/bug226.go b/test/fixedbugs/bug226.go
deleted file mode 100644
index 5457a64bc11..00000000000
--- a/test/fixedbugs/bug226.go
+++ /dev/null
@@ -1,7 +0,0 @@
-// $G $D/$F.dir/x.go && errchk $G $D/$F.dir/y.go
-
-// Copyright 2009 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.
-
-ignored
diff --git a/test/fixedbugs/bug310.go b/test/fixedbugs/bug310.go
deleted file mode 100644
index 191f3ed2b4e..00000000000
--- a/test/fixedbugs/bug310.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// errchk $G $D/$F.go
-
-// Copyright 2010 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 p
-
-import (
-	"bytes"
-	"fmt"
-)
-
-type t int
-
-func main() {
-	_ = t.bar	// ERROR "no method"
-	var b bytes.Buffer
-	fmt.Print(b)	// ERROR "implicit assignment"
-}
diff --git a/test/fixedbugs/bug359.go b/test/fixedbugs/bug359.go
deleted file mode 100644
index 3701499ed20..00000000000
--- a/test/fixedbugs/bug359.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// 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 1910
-// error on wrong line
-
-package main
-
-import "container/list"
-
-type Painting struct {
-	fragments list.List // private
-}
-
-func (p Painting) Foo() {
-	for e := p.fragments; e.Front() != nil; {  // ERROR "unexported field|hidden field"
-	}
-}
-
-// from comment 4 of issue 1910
-type Foo interface {
-	Run(a int) (a int)  // ERROR "a redeclared|redefinition|previous"
-}
diff --git a/test/fixedbugs/bug378.go b/test/fixedbugs/bug378.go
deleted file mode 100644
index 91975f2e931..00000000000
--- a/test/fixedbugs/bug378.go
+++ /dev/null
@@ -1,27 +0,0 @@
-// 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"
-}