runtime: Remove now unnecessary pad field from ParFor.

    
    It is not needed due to the removal of the ctx field.
    
    Reviewed-on: https://go-review.googlesource.com/16525


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@229616 138bc75d-0d04-0410-961f-82ee72b054a4

101 files changed, 19265 insertions, 426 deletions

diff --git a/libgo/go/go/ast/ast.go b/libgo/go/go/ast/ast.go
index 312e3d1b989..5ab4283826b 100644
--- a/libgo/go/go/ast/ast.go
+++ b/libgo/go/go/ast/ast.go
@@ -486,7 +486,7 @@ func (x *MapType) End() token.Pos       { return x.Value.End() }
 func (x *ChanType) End() token.Pos      { return x.Value.End() }
 
 // exprNode() ensures that only expression/type nodes can be
-// assigned to an ExprNode.
+// assigned to an Expr.
 //
 func (*BadExpr) exprNode()        {}
 func (*Ident) exprNode()          {}
@@ -562,10 +562,11 @@ type (
 
 	// An EmptyStmt node represents an empty statement.
 	// The "position" of the empty statement is the position
-	// of the immediately preceding semicolon.
+	// of the immediately following (explicit or implicit) semicolon.
 	//
 	EmptyStmt struct {
-		Semicolon token.Pos // position of preceding ";"
+		Semicolon token.Pos // position of following ";"
+		Implicit  bool      // if set, ";" was omitted in the source
 	}
 
 	// A LabeledStmt node represents a labeled statement.
@@ -734,6 +735,9 @@ func (s *RangeStmt) Pos() token.Pos      { return s.For }
 func (s *BadStmt) End() token.Pos  { return s.To }
 func (s *DeclStmt) End() token.Pos { return s.Decl.End() }
 func (s *EmptyStmt) End() token.Pos {
+	if s.Implicit {
+		return s.Semicolon
+	}
 	return s.Semicolon + 1 /* len(";") */
 }
 func (s *LabeledStmt) End() token.Pos { return s.Stmt.End() }
@@ -783,7 +787,7 @@ func (s *ForStmt) End() token.Pos    { return s.Body.End() }
 func (s *RangeStmt) End() token.Pos  { return s.Body.End() }
 
 // stmtNode() ensures that only statement nodes can be
-// assigned to a StmtNode.
+// assigned to a Stmt.
 //
 func (*BadStmt) stmtNode()        {}
 func (*DeclStmt) stmtNode()       {}
@@ -947,7 +951,7 @@ func (d *FuncDecl) End() token.Pos {
 }
 
 // declNode() ensures that only declaration nodes can be
-// assigned to a DeclNode.
+// assigned to a Decl.
 //
 func (*BadDecl) declNode()  {}
 func (*GenDecl) declNode()  {}
diff --git a/libgo/go/go/ast/filter.go b/libgo/go/go/ast/filter.go
index fc3eeb4a1db..bb571166f47 100644
--- a/libgo/go/go/ast/filter.go
+++ b/libgo/go/go/ast/filter.go
@@ -23,8 +23,7 @@ func exportFilter(name string) bool {
 // body) are removed. Non-exported fields and methods of exported types are
 // stripped. The File.Comments list is not changed.
 //
-// FileExports returns true if there are exported declarations;
-// it returns false otherwise.
+// FileExports reports whether there are exported declarations.
 //
 func FileExports(src *File) bool {
 	return filterFile(src, exportFilter, true)
@@ -34,7 +33,7 @@ func FileExports(src *File) bool {
 // only exported nodes remain. The pkg.Files list is not changed, so that
 // file names and top-level package comments don't get lost.
 //
-// PackageExports returns true if there are exported declarations;
+// PackageExports reports whether there are exported declarations;
 // it returns false otherwise.
 //
 func PackageExports(pkg *Package) bool {
@@ -199,8 +198,8 @@ func filterSpecList(list []Spec, f Filter, export bool) []Spec {
 // all names (including struct field and interface method names, but
 // not from parameter lists) that don't pass through the filter f.
 //
-// FilterDecl returns true if there are any declared names left after
-// filtering; it returns false otherwise.
+// FilterDecl reports whether there are any declared names left after
+// filtering.
 //
 func FilterDecl(decl Decl, f Filter) bool {
 	return filterDecl(decl, f, false)
@@ -221,11 +220,11 @@ func filterDecl(decl Decl, f Filter, export bool) bool {
 // names from top-level declarations (including struct field and
 // interface method names, but not from parameter lists) that don't
 // pass through the filter f. If the declaration is empty afterwards,
-// the declaration is removed from the AST. The File.Comments list
-// is not changed.
+// the declaration is removed from the AST. Import declarations are
+// always removed. The File.Comments list is not changed.
 //
-// FilterFile returns true if there are any top-level declarations
-// left after filtering; it returns false otherwise.
+// FilterFile reports whether there are any top-level declarations
+// left after filtering.
 //
 func FilterFile(src *File, f Filter) bool {
 	return filterFile(src, f, false)
@@ -251,8 +250,8 @@ func filterFile(src *File, f Filter, export bool) bool {
 // changed, so that file names and top-level package comments don't get
 // lost.
 //
-// FilterPackage returns true if there are any top-level declarations
-// left after filtering; it returns false otherwise.
+// FilterPackage reports whether there are any top-level declarations
+// left after filtering.
 //
 func FilterPackage(pkg *Package, f Filter) bool {
 	return filterPackage(pkg, f, false)
diff --git a/libgo/go/go/ast/scope.go b/libgo/go/go/ast/scope.go
index df1529d1819..1ce5e2e84b5 100644
--- a/libgo/go/go/ast/scope.go
+++ b/libgo/go/go/ast/scope.go
@@ -38,7 +38,7 @@ func (s *Scope) Lookup(name string) *Object {
 // Insert attempts to insert a named object obj into the scope s.
 // If the scope already contains an object alt with the same name,
 // Insert leaves the scope unchanged and returns alt. Otherwise
-// it inserts obj and returns nil."
+// it inserts obj and returns nil.
 //
 func (s *Scope) Insert(obj *Object) (alt *Object) {
 	if alt = s.Objects[obj.Name]; alt == nil {
diff --git a/libgo/go/go/ast/walk.go b/libgo/go/go/ast/walk.go
index 73ac38647a2..8ca21959b11 100644
--- a/libgo/go/go/ast/walk.go
+++ b/libgo/go/go/ast/walk.go
@@ -361,8 +361,7 @@ func Walk(v Visitor, node Node) {
 		}
 
 	default:
-		fmt.Printf("ast.Walk: unexpected node type %T", n)
-		panic("ast.Walk")
+		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
 	}
 
 	v.Visit(nil)
@@ -379,7 +378,8 @@ func (f inspector) Visit(node Node) Visitor {
 
 // Inspect traverses an AST in depth-first order: It starts by calling
 // f(node); node must not be nil. If f returns true, Inspect invokes f
-// for all the non-nil children of node, recursively.
+// recursively for each of the non-nil children of node, followed by a
+// call of f(nil).
 //
 func Inspect(node Node, f func(Node) bool) {
 	Walk(inspector(f), node)
diff --git a/libgo/go/go/build/build.go b/libgo/go/go/build/build.go
index e9247274b6e..42f11655b39 100644
--- a/libgo/go/go/build/build.go
+++ b/libgo/go/go/build/build.go
@@ -256,10 +256,12 @@ func (ctxt *Context) SrcDirs() []string {
 // if set, or else the compiled code's GOARCH, GOOS, and GOROOT.
 var Default Context = defaultContext()
 
+// Also known to cmd/dist/build.go.
 var cgoEnabled = map[string]bool{
 	"darwin/386":      true,
 	"darwin/amd64":    true,
-	"dragonfly/386":   true,
+	"darwin/arm":      true,
+	"darwin/arm64":    true,
 	"dragonfly/amd64": true,
 	"freebsd/386":     true,
 	"freebsd/amd64":   true,
@@ -282,6 +284,7 @@ var cgoEnabled = map[string]bool{
 	"netbsd/arm":      true,
 	"openbsd/386":     true,
 	"openbsd/amd64":   true,
+	"solaris/amd64":   true,
 	"windows/386":     true,
 	"windows/amd64":   true,
 }
@@ -300,11 +303,7 @@ func defaultContext() Context {
 	// in all releases >= Go 1.x. Code that requires Go 1.x or later should
 	// say "+build go1.x", and code that should only be built before Go 1.x
 	// (perhaps it is the stub to use in that case) should say "+build !go1.x".
-	//
-	// When we reach Go 1.5 the line will read
-	//	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5"}
-	// and so on.
-	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4"}
+	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5"}
 
 	switch os.Getenv("CGO_ENABLED") {
 	case "1":
@@ -361,6 +360,7 @@ type Package struct {
 	Root          string   // root of Go tree where this package lives
 	SrcRoot       string   // package source root directory ("" if unknown)
 	PkgRoot       string   // package install root directory ("" if unknown)
+	PkgTargetRoot string   // architecture dependent install root directory ("" if unknown)
 	BinDir        string   // command install directory ("" if unknown)
 	Goroot        bool     // package found in Go root
 	PkgObj        string   // installed .a file
@@ -469,18 +469,21 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 		return p, fmt.Errorf("import %q: invalid import path", path)
 	}
 
+	var pkgtargetroot string
 	var pkga string
 	var pkgerr error
+	suffix := ""
+	if ctxt.InstallSuffix != "" {
+		suffix = "_" + ctxt.InstallSuffix
+	}
 	switch ctxt.Compiler {
 	case "gccgo":
+		pkgtargetroot = "pkg/gccgo_" + ctxt.GOOS + "_" + ctxt.GOARCH + suffix
 		dir, elem := pathpkg.Split(p.ImportPath)
-		pkga = "pkg/gccgo_" + ctxt.GOOS + "_" + ctxt.GOARCH + "/" + dir + "lib" + elem + ".a"
+		pkga = pkgtargetroot + "/" + dir + "lib" + elem + ".a"
 	case "gc":
-		suffix := ""
-		if ctxt.InstallSuffix != "" {
-			suffix = "_" + ctxt.InstallSuffix
-		}
-		pkga = "pkg/" + ctxt.GOOS + "_" + ctxt.GOARCH + suffix + "/" + p.ImportPath + ".a"
+		pkgtargetroot = "pkg/" + ctxt.GOOS + "_" + ctxt.GOARCH + suffix
+		pkga = pkgtargetroot + "/" + p.ImportPath + ".a"
 	default:
 		// Save error for end of function.
 		pkgerr = fmt.Errorf("import %q: unknown compiler %q", path, ctxt.Compiler)
@@ -496,9 +499,13 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 			p.Dir = ctxt.joinPath(srcDir, path)
 		}
 		// Determine canonical import path, if any.
+		// Exclude results where the import path would include /testdata/.
+		inTestdata := func(sub string) bool {
+			return strings.Contains(sub, "/testdata/") || strings.HasSuffix(sub, "/testdata") || strings.HasPrefix(sub, "testdata/") || sub == "testdata"
+		}
 		if ctxt.GOROOT != "" {
 			root := ctxt.joinPath(ctxt.GOROOT, "src")
-			if sub, ok := ctxt.hasSubdir(root, p.Dir); ok {
+			if sub, ok := ctxt.hasSubdir(root, p.Dir); ok && !inTestdata(sub) {
 				p.Goroot = true
 				p.ImportPath = sub
 				p.Root = ctxt.GOROOT
@@ -508,7 +515,7 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 		all := ctxt.gopath()
 		for i, root := range all {
 			rootsrc := ctxt.joinPath(root, "src")
-			if sub, ok := ctxt.hasSubdir(rootsrc, p.Dir); ok {
+			if sub, ok := ctxt.hasSubdir(rootsrc, p.Dir); ok && !inTestdata(sub) {
 				// We found a potential import path for dir,
 				// but check that using it wouldn't find something
 				// else first.
@@ -597,6 +604,7 @@ Found:
 		p.PkgRoot = ctxt.joinPath(p.Root, "pkg")
 		p.BinDir = ctxt.joinPath(p.Root, "bin")
 		if pkga != "" {
+			p.PkgTargetRoot = ctxt.joinPath(p.Root, pkgtargetroot)
 			p.PkgObj = ctxt.joinPath(p.Root, pkga)
 		}
 	}
@@ -695,7 +703,11 @@ Found:
 			p.Name = pkg
 			firstFile = name
 		} else if pkg != p.Name {
-			return p, &MultiplePackageError{p.Dir, []string{firstFile, name}, []string{p.Name, pkg}}
+			return p, &MultiplePackageError{
+				Dir:      p.Dir,
+				Packages: []string{p.Name, pkg},
+				Files:    []string{firstFile, name},
+			}
 		}
 		if pf.Doc != nil && p.Doc == "" {
 			p.Doc = doc.Synopsis(pf.Doc.Text())
@@ -962,7 +974,7 @@ func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map
 	}
 
 	if strings.HasSuffix(filename, ".go") {
-		data, err = readImports(f, false)
+		data, err = readImports(f, false, nil)
 	} else {
 		data, err = readComments(f)
 	}
@@ -1075,9 +1087,6 @@ func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) bool {
 // saveCgo saves the information from the #cgo lines in the import "C" comment.
 // These lines set CFLAGS, CPPFLAGS, CXXFLAGS and LDFLAGS and pkg-config directives
 // that affect the way cgo's C code is built.
-//
-// TODO(rsc): This duplicates code in cgo.
-// Once the dust settles, remove this code from cgo.
 func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup) error {
 	text := cg.Text()
 	for _, line := range strings.Split(text, "\n") {
@@ -1123,10 +1132,12 @@ func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup)
 		if err != nil {
 			return fmt.Errorf("%s: invalid #cgo line: %s", filename, orig)
 		}
-		for _, arg := range args {
+		for i, arg := range args {
+			arg = expandSrcDir(arg, di.Dir)
 			if !safeCgoName(arg) {
 				return fmt.Errorf("%s: malformed #cgo argument: %s", filename, arg)
 			}
+			args[i] = arg
 		}
 
 		switch verb {
@@ -1147,6 +1158,14 @@ func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup)
 	return nil
 }
 
+func expandSrcDir(str string, srcdir string) string {
+	// "\" delimited paths cause safeCgoName to fail
+	// so convert native paths with a different delimeter
+	// to "/" before starting (eg: on windows)
+	srcdir = filepath.ToSlash(srcdir)
+	return strings.Replace(str, "${SRCDIR}", srcdir, -1)
+}
+
 // NOTE: $ is not safe for the shell, but it is allowed here because of linker options like -Wl,$ORIGIN.
 // We never pass these arguments to a shell (just to programs we construct argv for), so this should be okay.
 // See golang.org/issue/6038.
@@ -1225,7 +1244,7 @@ func splitQuoted(s string) (r []string, err error) {
 	return args, err
 }
 
-// match returns true if the name is one of:
+// match reports whether the name is one of:
 //
 //	$GOOS
 //	$GOARCH
@@ -1316,7 +1335,7 @@ func (ctxt *Context) goodOSArchFile(name string, allTags map[string]bool) bool {
 	// build tag "linux" in that file. For Go 1.4 and beyond, we require this
 	// auto-tagging to apply only to files with a non-empty prefix, so
 	// "foo_linux.go" is tagged but "linux.go" is not. This allows new operating
-	// sytems, such as android, to arrive without breaking existing code with
+	// systems, such as android, to arrive without breaking existing code with
 	// innocuous source code in "android.go". The easiest fix: cut everything
 	// in the name before the initial _.
 	i := strings.Index(name, "_")
@@ -1390,20 +1409,11 @@ func IsLocalImport(path string) bool {
 		strings.HasPrefix(path, "./") || strings.HasPrefix(path, "../")
 }
 
-// ArchChar returns the architecture character for the given goarch.
-// For example, ArchChar("amd64") returns "6".
+// ArchChar returns "?" and an error.
+// In earlier versions of Go, the returned string was used to derive
+// the compiler and linker tool names, the default object file suffix,
+// and the default linker output name. As of Go 1.5, those strings
+// no longer vary by architecture; they are compile, link, .o, and a.out, respectively.
 func ArchChar(goarch string) (string, error) {
-	switch goarch {
-	case "386":
-		return "8", nil
-	case "amd64", "amd64p32":
-		return "6", nil
-	case "arm":
-		return "5", nil
-	case "arm64":
-		return "7", nil
-	case "ppc64", "ppc64le":
-		return "9", nil
-	}
-	return "", errors.New("unsupported GOARCH " + goarch)
+	return "?", errors.New("architecture letter no longer used")
 }
diff --git a/libgo/go/go/build/build_test.go b/libgo/go/go/build/build_test.go
index a40def0fa0e..2709ca34f54 100644
--- a/libgo/go/go/build/build_test.go
+++ b/libgo/go/go/build/build_test.go
@@ -94,12 +94,29 @@ func TestEmptyFolderImport(t *testing.T) {
 
 func TestMultiplePackageImport(t *testing.T) {
 	_, err := Import(".", "testdata/multi", 0)
-	if _, ok := err.(*MultiplePackageError); !ok {
+	mpe, ok := err.(*MultiplePackageError)
+	if !ok {
 		t.Fatal(`Import("testdata/multi") did not return MultiplePackageError.`)
 	}
+	want := &MultiplePackageError{
+		Dir:      filepath.FromSlash("testdata/multi"),
+		Packages: []string{"main", "test_package"},
+		Files:    []string{"file.go", "file_appengine.go"},
+	}
+	if !reflect.DeepEqual(mpe, want) {
+		t.Errorf("got %#v; want %#v", mpe, want)
+	}
 }
 
 func TestLocalDirectory(t *testing.T) {
+	t.Skip("does not work with gccgo")
+	if runtime.GOOS == "darwin" {
+		switch runtime.GOARCH {
+		case "arm", "arm64":
+			t.Skipf("skipping on %s/%s, no valid GOROOT", runtime.GOOS, runtime.GOARCH)
+		}
+	}
+
 	cwd, err := os.Getwd()
 	if err != nil {
 		t.Fatal(err)
@@ -214,6 +231,14 @@ func TestMatchFile(t *testing.T) {
 }
 
 func TestImportCmd(t *testing.T) {
+	t.Skip("does not work with gccgo")
+	if runtime.GOOS == "darwin" {
+		switch runtime.GOARCH {
+		case "arm", "arm64":
+			t.Skipf("skipping on %s/%s, no valid GOROOT", runtime.GOOS, runtime.GOARCH)
+		}
+	}
+
 	p, err := Import("cmd/internal/objfile", "", 0)
 	if err != nil {
 		t.Fatal(err)
@@ -222,3 +247,33 @@ func TestImportCmd(t *testing.T) {
 		t.Fatalf("Import cmd/internal/objfile returned Dir=%q, want %q", filepath.ToSlash(p.Dir), ".../src/cmd/internal/objfile")
 	}
 }
+
+var (
+	expandSrcDirPath = filepath.Join(string(filepath.Separator)+"projects", "src", "add")
+)
+
+var expandSrcDirTests = []struct {
+	input, expected string
+}{
+	{"-L ${SRCDIR}/libs -ladd", "-L /projects/src/add/libs -ladd"},
+	{"${SRCDIR}/add_linux_386.a -pthread -lstdc++", "/projects/src/add/add_linux_386.a -pthread -lstdc++"},
+	{"Nothing to expand here!", "Nothing to expand here!"},
+	{"$", "$"},
+	{"$$", "$$"},
+	{"${", "${"},
+	{"$}", "$}"},
+	{"$FOO ${BAR}", "$FOO ${BAR}"},
+	{"Find me the $SRCDIRECTORY.", "Find me the $SRCDIRECTORY."},
+	{"$SRCDIR is missing braces", "$SRCDIR is missing braces"},
+}
+
+func TestExpandSrcDir(t *testing.T) {
+	for _, test := range expandSrcDirTests {
+		output := expandSrcDir(test.input, expandSrcDirPath)
+		if output != test.expected {
+			t.Errorf("%q expands to %q with SRCDIR=%q when %q is expected", test.input, output, expandSrcDirPath, test.expected)
+		} else {
+			t.Logf("%q expands to %q with SRCDIR=%q", test.input, output, expandSrcDirPath)
+		}
+	}
+}
diff --git a/libgo/go/go/build/deps_test.go b/libgo/go/go/build/deps_test.go
index a335effec3a..68969bbcf86 100644
--- a/libgo/go/go/build/deps_test.go
+++ b/libgo/go/go/build/deps_test.go
@@ -8,8 +8,15 @@
 package build
 
 import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"runtime"
 	"sort"
+	"strconv"
+	"strings"
 	"testing"
 )
 
@@ -121,9 +128,12 @@ var pkgDeps = map[string][]string{
 	// End of linear dependency definitions.
 
 	// Operating system access.
-	"syscall":       {"L0", "unicode/utf16"},
-	"time":          {"L0", "syscall"},
-	"os":            {"L1", "os", "syscall", "time"},
+	"syscall":                           {"L0", "unicode/utf16"},
+	"internal/syscall/unix":             {"L0", "syscall"},
+	"internal/syscall/windows":          {"L0", "syscall"},
+	"internal/syscall/windows/registry": {"L0", "syscall", "unicode/utf16"},
+	"time":          {"L0", "syscall", "internal/syscall/windows/registry"},
+	"os":            {"L1", "os", "syscall", "time", "internal/syscall/windows"},
 	"path/filepath": {"L2", "os", "syscall"},
 	"io/ioutil":     {"L2", "os", "path/filepath", "time"},
 	"os/exec":       {"L2", "os", "path/filepath", "syscall"},
@@ -148,11 +158,13 @@ var pkgDeps = map[string][]string{
 	"regexp/syntax":  {"L2"},
 	"runtime/debug":  {"L2", "fmt", "io/ioutil", "os", "time"},
 	"runtime/pprof":  {"L2", "fmt", "text/tabwriter"},
+	"runtime/trace":  {"L0"},
 	"text/tabwriter": {"L2"},
 
-	"testing":        {"L2", "flag", "fmt", "os", "runtime/pprof", "time"},
-	"testing/iotest": {"L2", "log"},
-	"testing/quick":  {"L2", "flag", "fmt", "reflect"},
+	"testing":          {"L2", "flag", "fmt", "os", "runtime/pprof", "runtime/trace", "time"},
+	"testing/iotest":   {"L2", "log"},
+	"testing/quick":    {"L2", "flag", "fmt", "reflect"},
+	"internal/testenv": {"L2", "os", "testing"},
 
 	// L4 is defined as L3+fmt+log+time, because in general once
 	// you're using L3 packages, use of fmt, log, or time is not a big deal.
@@ -180,43 +192,60 @@ var pkgDeps = map[string][]string{
 		"go/token",
 	},
 
+	"go/format":       {"L4", "GOPARSER", "internal/format"},
+	"internal/format": {"L4", "GOPARSER"},
+
+	// Go type checking.
+	"go/constant":               {"L4", "go/token", "math/big"},
+	"go/importer":               {"L4", "go/internal/gcimporter", "go/internal/gccgoimporter", "go/types"},
+	"go/internal/gcimporter":    {"L4", "OS", "go/build", "go/constant", "go/token", "go/types", "text/scanner"},
+	"go/internal/gccgoimporter": {"L4", "OS", "debug/elf", "go/constant", "go/token", "go/types", "text/scanner"},
+	"go/types":                  {"L4", "GOPARSER", "container/heap", "go/constant"},
+
 	// One of a kind.
-	"archive/tar":         {"L4", "OS", "syscall"},
-	"archive/zip":         {"L4", "OS", "compress/flate"},
-	"compress/bzip2":      {"L4"},
-	"compress/flate":      {"L4"},
-	"compress/gzip":       {"L4", "compress/flate"},
-	"compress/lzw":        {"L4"},
-	"compress/zlib":       {"L4", "compress/flate"},
-	"database/sql":        {"L4", "container/list", "database/sql/driver"},
-	"database/sql/driver": {"L4", "time"},
-	"debug/dwarf":         {"L4"},
-	"debug/elf":           {"L4", "OS", "debug/dwarf"},
-	"debug/gosym":         {"L4"},
-	"debug/macho":         {"L4", "OS", "debug/dwarf"},
-	"debug/pe":            {"L4", "OS", "debug/dwarf"},
-	"encoding":            {"L4"},
-	"encoding/ascii85":    {"L4"},
-	"encoding/asn1":       {"L4", "math/big"},
-	"encoding/csv":        {"L4"},
-	"encoding/gob":        {"L4", "OS", "encoding"},
-	"encoding/hex":        {"L4"},
-	"encoding/json":       {"L4", "encoding"},
-	"encoding/pem":        {"L4"},
-	"encoding/xml":        {"L4", "encoding"},
-	"flag":                {"L4", "OS"},
-	"go/build":            {"L4", "OS", "GOPARSER"},
-	"html":                {"L4"},
-	"image/draw":          {"L4"},
-	"image/gif":           {"L4", "compress/lzw", "image/color/palette", "image/draw"},
-	"image/jpeg":          {"L4"},
-	"image/png":           {"L4", "compress/zlib"},
-	"index/suffixarray":   {"L4", "regexp"},
-	"math/big":            {"L4"},
-	"mime":                {"L4", "OS", "syscall"},
-	"net/url":             {"L4"},
-	"text/scanner":        {"L4", "OS"},
-	"text/template/parse": {"L4"},
+	"archive/tar":              {"L4", "OS", "syscall"},
+	"archive/zip":              {"L4", "OS", "compress/flate"},
+	"container/heap":           {"sort"},
+	"compress/bzip2":           {"L4"},
+	"compress/flate":           {"L4"},
+	"compress/gzip":            {"L4", "compress/flate"},
+	"compress/lzw":             {"L4"},
+	"compress/zlib":            {"L4", "compress/flate"},
+	"database/sql":             {"L4", "container/list", "database/sql/driver"},
+	"database/sql/driver":      {"L4", "time"},
+	"debug/dwarf":              {"L4"},
+	"debug/elf":                {"L4", "OS", "debug/dwarf"},
+	"debug/gosym":              {"L4"},
+	"debug/macho":              {"L4", "OS", "debug/dwarf"},
+	"debug/pe":                 {"L4", "OS", "debug/dwarf"},
+	"debug/plan9obj":           {"L4", "OS"},
+	"encoding":                 {"L4"},
+	"encoding/ascii85":         {"L4"},
+	"encoding/asn1":            {"L4", "math/big"},
+	"encoding/csv":             {"L4"},
+	"encoding/gob":             {"L4", "OS", "encoding"},
+	"encoding/hex":             {"L4"},
+	"encoding/json":            {"L4", "encoding"},
+	"encoding/pem":             {"L4"},
+	"encoding/xml":             {"L4", "encoding"},
+	"flag":                     {"L4", "OS"},
+	"go/build":                 {"L4", "OS", "GOPARSER"},
+	"html":                     {"L4"},
+	"image/draw":               {"L4", "image/internal/imageutil"},
+	"image/gif":                {"L4", "compress/lzw", "image/color/palette", "image/draw"},
+	"image/internal/imageutil": {"L4"},
+	"image/jpeg":               {"L4", "image/internal/imageutil"},
+	"image/png":                {"L4", "compress/zlib"},
+	"index/suffixarray":        {"L4", "regexp"},
+	"internal/singleflight":    {"sync"},
+	"internal/trace":           {"L4", "OS"},
+	"math/big":                 {"L4"},
+	"mime":                     {"L4", "OS", "syscall", "internal/syscall/windows/registry"},
+	"mime/quotedprintable":     {"L4"},
+	"net/internal/socktest":    {"L4", "OS", "syscall"},
+	"net/url":                  {"L4"},
+	"text/scanner":             {"L4", "OS"},
+	"text/template/parse":      {"L4"},
 
 	"html/template": {
 		"L4", "OS", "encoding/json", "html", "text/template",
@@ -234,13 +263,16 @@ var pkgDeps = map[string][]string{
 	// that shows up in programs that use cgo.
 	"C": {},
 
+	// Race detector uses cgo.
+	"runtime/race": {"C"},
+
 	// Plan 9 alone needs io/ioutil and os.
 	"os/user": {"L4", "CGO", "io/ioutil", "os", "syscall"},
 
 	// Basic networking.
 	// Because net must be used by any package that wants to
 	// do networking portably, it must have a small dependency set: just L1+basic os.
-	"net": {"L1", "CGO", "os", "syscall", "time"},
+	"net": {"L1", "CGO", "os", "syscall", "time", "internal/syscall/windows", "internal/singleflight"},
 
 	// NET enables use of basic network-related packages.
 	"NET": {
@@ -252,7 +284,7 @@ var pkgDeps = map[string][]string{
 
 	// Uses of networking.
 	"log/syslog":    {"L4", "OS", "net"},
-	"net/mail":      {"L4", "NET", "OS"},
+	"net/mail":      {"L4", "NET", "OS", "mime"},
 	"net/textproto": {"L4", "OS", "net"},
 
 	// Core crypto.
@@ -279,7 +311,7 @@ var pkgDeps = map[string][]string{
 	// Random byte, number generation.
 	// This would be part of core crypto except that it imports
 	// math/big, which imports fmt.
-	"crypto/rand": {"L4", "CRYPTO", "OS", "math/big", "syscall", "internal/syscall"},
+	"crypto/rand": {"L4", "CRYPTO", "OS", "math/big", "syscall", "internal/syscall/unix"},
 
 	// Mathematical crypto: dependencies on fmt (L4) and math/big.
 	// We could avoid some of the fmt, but math/big imports fmt anyway.
@@ -311,7 +343,7 @@ var pkgDeps = map[string][]string{
 	"crypto/x509/pkix": {"L4", "CRYPTO-MATH"},
 
 	// Simple net+crypto-aware packages.
-	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto"},
+	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto", "mime/quotedprintable"},
 	"net/smtp":       {"L4", "CRYPTO", "NET", "crypto/tls"},
 
 	// HTTP, kingpin of dependencies.
@@ -320,16 +352,18 @@ var pkgDeps = map[string][]string{
 		"compress/gzip", "crypto/tls", "mime/multipart", "runtime/debug",
 		"net/http/internal",
 	},
+	"net/http/internal": {"L4"},
 
 	// HTTP-using packages.
-	"expvar":            {"L4", "OS", "encoding/json", "net/http"},
-	"net/http/cgi":      {"L4", "NET", "OS", "crypto/tls", "net/http", "regexp"},
-	"net/http/fcgi":     {"L4", "NET", "OS", "net/http", "net/http/cgi"},
-	"net/http/httptest": {"L4", "NET", "OS", "crypto/tls", "flag", "net/http"},
-	"net/http/httputil": {"L4", "NET", "OS", "net/http", "net/http/internal"},
-	"net/http/pprof":    {"L4", "OS", "html/template", "net/http", "runtime/pprof"},
-	"net/rpc":           {"L4", "NET", "encoding/gob", "html/template", "net/http"},
-	"net/rpc/jsonrpc":   {"L4", "NET", "encoding/json", "net/rpc"},
+	"expvar":             {"L4", "OS", "encoding/json", "net/http"},
+	"net/http/cgi":       {"L4", "NET", "OS", "crypto/tls", "net/http", "regexp"},
+	"net/http/cookiejar": {"L4", "NET", "net/http"},
+	"net/http/fcgi":      {"L4", "NET", "OS", "net/http", "net/http/cgi"},
+	"net/http/httptest":  {"L4", "NET", "OS", "crypto/tls", "flag", "net/http"},
+	"net/http/httputil":  {"L4", "NET", "OS", "net/http", "net/http/internal"},
+	"net/http/pprof":     {"L4", "OS", "html/template", "net/http", "runtime/pprof", "runtime/trace"},
+	"net/rpc":            {"L4", "NET", "encoding/gob", "html/template", "net/http"},
+	"net/rpc/jsonrpc":    {"L4", "NET", "encoding/json", "net/rpc"},
 }
 
 // isMacro reports whether p is a package dependency macro
@@ -375,69 +409,112 @@ var allowedErrors = map[osPkg]bool{
 	osPkg{"plan9", "log/syslog"}:   true,
 }
 
+// listStdPkgs returns the same list of packages as "go list std".
+func listStdPkgs(goroot string) ([]string, error) {
+	// Based on cmd/go's matchPackages function.
+	var pkgs []string
+
+	src := filepath.Join(goroot, "src") + string(filepath.Separator)
+	walkFn := func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() || path == src {
+			return nil
+		}
+
+		base := filepath.Base(path)
+		if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
+			return filepath.SkipDir
+		}
+
+		name := filepath.ToSlash(path[len(src):])
+		if name == "builtin" || name == "cmd" || strings.Contains(name, ".") {
+			return filepath.SkipDir
+		}
+
+		pkgs = append(pkgs, name)
+		return nil
+	}
+	if err := filepath.Walk(src, walkFn); err != nil {
+		return nil, err
+	}
+	return pkgs, nil
+}
+
 func TestDependencies(t *testing.T) {
-	if runtime.GOOS == "nacl" {
-		// NaCl tests run in a limited file system and we do not
+	iOS := runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64")
+	if runtime.GOOS == "nacl" || iOS {
+		// Tests run in a limited file system and we do not
 		// provide access to every source file.
-		t.Skip("skipping on NaCl")
+		t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 	}
-	var all []string
 
-	for k := range pkgDeps {
-		all = append(all, k)
+	ctxt := Default
+	all, err := listStdPkgs(ctxt.GOROOT)
+	if err != nil {
+		t.Fatal(err)
 	}
 	sort.Strings(all)
 
-	ctxt := Default
 	test := func(mustImport bool) {
 		for _, pkg := range all {
-			if isMacro(pkg) {
-				continue
-			}
-			if pkg == "runtime/cgo" && !ctxt.CgoEnabled {
-				continue
-			}
-			p, err := ctxt.Import(pkg, "", 0)
+			imports, err := findImports(pkg)
 			if err != nil {
-				if allowedErrors[osPkg{ctxt.GOOS, pkg}] {
-					continue
-				}
-				if !ctxt.CgoEnabled && pkg == "runtime/cgo" {
-					continue
-				}
-				// Some of the combinations we try might not
-				// be reasonable (like arm,plan9,cgo), so ignore
-				// errors for the auto-generated combinations.
-				if !mustImport {
-					continue
-				}
-				t.Errorf("%s/%s/cgo=%v %v", ctxt.GOOS, ctxt.GOARCH, ctxt.CgoEnabled, err)
+				t.Error(err)
 				continue
 			}
 			ok := allowed(pkg)
 			var bad []string
-			for _, imp := range p.Imports {
+			for _, imp := range imports {
 				if !ok[imp] {
 					bad = append(bad, imp)
 				}
 			}
 			if bad != nil {
-				t.Errorf("%s/%s/cgo=%v unexpected dependency: %s imports %v", ctxt.GOOS, ctxt.GOARCH, ctxt.CgoEnabled, pkg, bad)
+				t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
 			}
 		}
 	}
 	test(true)
+}
 
-	if testing.Short() {
-		t.Logf("skipping other systems")
-		return
-	}
+var buildIgnore = []byte("\n// +build ignore")
 
-	for _, ctxt.GOOS = range geese {
-		for _, ctxt.GOARCH = range goarches {
-			for _, ctxt.CgoEnabled = range bools {
-				test(false)
+func findImports(pkg string) ([]string, error) {
+	dir := filepath.Join(Default.GOROOT, "src", pkg)
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+	var imports []string
+	var haveImport = map[string]bool{}
+	for _, file := range files {
+		name := file.Name()
+		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			continue
+		}
+		f, err := os.Open(filepath.Join(dir, name))
+		if err != nil {
+			return nil, err
+		}
+		var imp []string
+		data, err := readImports(f, false, &imp)
+		f.Close()
+		if err != nil {
+			return nil, fmt.Errorf("reading %v: %v", name, err)
+		}
+		if bytes.Contains(data, buildIgnore) {
+			continue
+		}
+		for _, quoted := range imp {
+			path, err := strconv.Unquote(quoted)
+			if err != nil {
+				continue
+			}
+			if !haveImport[path] {
+				haveImport[path] = true
+				imports = append(imports, path)
 			}
 		}
 	}
+	sort.Strings(imports)
+	return imports, nil
 }
diff --git a/libgo/go/go/build/doc.go b/libgo/go/go/build/doc.go
index 75a827bb91f..233f8b989d5 100644
--- a/libgo/go/go/build/doc.go
+++ b/libgo/go/go/build/doc.go
@@ -101,6 +101,7 @@
 //	- "go1.2", from Go version 1.2 onward
 //	- "go1.3", from Go version 1.3 onward
 //	- "go1.4", from Go version 1.4 onward
+//	- "go1.5", from Go version 1.5 onward
 //	- any additional words listed in ctxt.BuildTags
 //
 // If a file's name, after stripping the extension and a possible _test suffix,
@@ -111,7 +112,7 @@
 // (example: source_windows_amd64.go) where GOOS and GOARCH represent
 // any known operating system and architecture values respectively, then
 // the file is considered to have an implicit build constraint requiring
-// those terms.
+// those terms (in addition to any explicit constraints in the file).
 //
 // To keep a file from being considered for the build:
 //
diff --git a/libgo/go/go/build/read.go b/libgo/go/go/build/read.go
index c8079dfd15d..1049ac50d94 100644
--- a/libgo/go/go/build/read.go
+++ b/libgo/go/go/build/read.go
@@ -146,11 +146,15 @@ func (r *importReader) readIdent() {
 
 // readString reads a quoted string literal from the input.
 // If an identifier is not present, readString records a syntax error.
-func (r *importReader) readString() {
+func (r *importReader) readString(save *[]string) {
 	switch r.nextByte(true) {
 	case '`':
+		start := len(r.buf) - 1
 		for r.err == nil {
 			if r.nextByte(false) == '`' {
+				if save != nil {
+					*save = append(*save, string(r.buf[start:]))
+				}
 				break
 			}
 			if r.eof {
@@ -158,9 +162,13 @@ func (r *importReader) readString() {
 			}
 		}
 	case '"':
+		start := len(r.buf) - 1
 		for r.err == nil {
 			c := r.nextByte(false)
 			if c == '"' {
+				if save != nil {
+					*save = append(*save, string(r.buf[start:]))
+				}
 				break
 			}
 			if r.eof || c == '\n' {
@@ -177,14 +185,14 @@ func (r *importReader) readString() {
 
 // readImport reads an import clause - optional identifier followed by quoted string -
 // from the input.
-func (r *importReader) readImport() {
+func (r *importReader) readImport(imports *[]string) {
 	c := r.peekByte(true)
 	if c == '.' {
 		r.peek = 0
 	} else if isIdent(c) {
 		r.readIdent()
 	}
-	r.readString()
+	r.readString(imports)
 }
 
 // readComments is like ioutil.ReadAll, except that it only reads the leading
@@ -201,7 +209,7 @@ func readComments(f io.Reader) ([]byte, error) {
 
 // readImports is like ioutil.ReadAll, except that it expects a Go file as input
 // and stops reading the input once the imports have completed.
-func readImports(f io.Reader, reportSyntaxError bool) ([]byte, error) {
+func readImports(f io.Reader, reportSyntaxError bool, imports *[]string) ([]byte, error) {
 	r := &importReader{b: bufio.NewReader(f)}
 
 	r.readKeyword("package")
@@ -211,11 +219,11 @@ func readImports(f io.Reader, reportSyntaxError bool) ([]byte, error) {
 		if r.peekByte(true) == '(' {
 			r.nextByte(false)
 			for r.peekByte(true) != ')' && r.err == nil {
-				r.readImport()
+				r.readImport(imports)
 			}
 			r.nextByte(false)
 		} else {
-			r.readImport()
+			r.readImport(imports)
 		}
 	}
 
diff --git a/libgo/go/go/build/read_test.go b/libgo/go/go/build/read_test.go
index 2dcc1208f71..326960bdc91 100644
--- a/libgo/go/go/build/read_test.go
+++ b/libgo/go/go/build/read_test.go
@@ -131,7 +131,7 @@ func testRead(t *testing.T, tests []readTest, read func(io.Reader) ([]byte, erro
 }
 
 func TestReadImports(t *testing.T) {
-	testRead(t, readImportsTests, func(r io.Reader) ([]byte, error) { return readImports(r, true) })
+	testRead(t, readImportsTests, func(r io.Reader) ([]byte, error) { return readImports(r, true, nil) })
 }
 
 func TestReadComments(t *testing.T) {
@@ -207,7 +207,7 @@ var readFailuresTests = []readTest{
 
 func TestReadFailures(t *testing.T) {
 	// Errors should be reported (true arg to readImports).
-	testRead(t, readFailuresTests, func(r io.Reader) ([]byte, error) { return readImports(r, true) })
+	testRead(t, readFailuresTests, func(r io.Reader) ([]byte, error) { return readImports(r, true, nil) })
 }
 
 func TestReadFailuresIgnored(t *testing.T) {
@@ -222,5 +222,5 @@ func TestReadFailuresIgnored(t *testing.T) {
 			tt.err = ""
 		}
 	}
-	testRead(t, tests, func(r io.Reader) ([]byte, error) { return readImports(r, false) })
+	testRead(t, tests, func(r io.Reader) ([]byte, error) { return readImports(r, false, nil) })
 }
diff --git a/libgo/go/go/build/syslist.go b/libgo/go/go/build/syslist.go
index 0bf4b1573c9..d800a78f0a1 100644
--- a/libgo/go/go/build/syslist.go
+++ b/libgo/go/go/build/syslist.go
@@ -5,4 +5,4 @@
 package build
 
 const goosList = "android darwin dragonfly freebsd linux nacl netbsd openbsd plan9 solaris windows "
-const goarchList = "386 amd64 amd64p32 arm arm64 alpha m68k mipso32 mipsn32 mipsn64 mipso64 ppc ppc64 ppc64le s390 s390x sparc sparc64 "
+const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be alpha m68k ppc64 ppc64le mips mipsle mips64 mips64le mips64p32 mips64p32le mipso32 mipsn32 mipsn64 mipso64 ppc s390 s390x sparc sparc64 "
diff --git a/libgo/go/go/build/testdata/empty/dummy b/libgo/go/go/build/testdata/empty/dummy
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/libgo/go/go/build/testdata/empty/dummy
diff --git a/libgo/go/go/constant/go13.go b/libgo/go/go/constant/go13.go
new file mode 100644
index 00000000000..a4a838a2908
--- /dev/null
+++ b/libgo/go/go/constant/go13.go
@@ -0,0 +1,24 @@
+// Copyright 2014 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.
+
+// +build !go1.4
+
+package constant
+
+import (
+	"math"
+	"math/big"
+)
+
+func ratToFloat32(x *big.Rat) (float32, bool) {
+	// Before 1.4, there's no Rat.Float32.
+	// Emulate it, albeit at the cost of
+	// imprecision in corner cases.
+	x64, exact := x.Float64()
+	x32 := float32(x64)
+	if math.IsInf(float64(x32), 0) {
+		exact = false
+	}
+	return x32, exact
+}
diff --git a/libgo/go/go/constant/go14.go b/libgo/go/go/constant/go14.go
new file mode 100644
index 00000000000..2ab6da02f67
--- /dev/null
+++ b/libgo/go/go/constant/go14.go
@@ -0,0 +1,13 @@
+// Copyright 2014 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.
+
+// +build go1.4
+
+package constant
+
+import "math/big"
+
+func ratToFloat32(x *big.Rat) (float32, bool) {
+	return x.Float32()
+}
diff --git a/libgo/go/go/constant/value.go b/libgo/go/go/constant/value.go
new file mode 100644
index 00000000000..79a80af1ab1
--- /dev/null
+++ b/libgo/go/go/constant/value.go
@@ -0,0 +1,925 @@
+// Copyright 2013 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 constant implements Values representing untyped
+// Go constants and the corresponding operations. Values
+// and operations may have arbitrary or unlimited precision.
+//
+// A special Unknown value may be used when a value
+// is unknown due to an error. Operations on unknown
+// values produce unknown values unless specified
+// otherwise.
+//
+package constant // import "go/constant"
+
+import (
+	"fmt"
+	"go/token"
+	"math/big"
+	"strconv"
+)
+
+// Kind specifies the kind of value represented by a Value.
+type Kind int
+
+// Implementation note: Kinds must be enumerated in
+// order of increasing "complexity" (used by match).
+
+const (
+	// unknown values
+	Unknown Kind = iota
+
+	// non-numeric values
+	Bool
+	String
+
+	// numeric values
+	Int
+	Float
+	Complex
+)
+
+// A Value represents a mathematically exact value of a given Kind.
+type Value interface {
+	// Kind returns the value kind; it is always the smallest
+	// kind in which the value can be represented exactly.
+	Kind() Kind
+
+	// String returns a human-readable form of the value.
+	String() string
+
+	// Prevent external implementations.
+	implementsValue()
+}
+
+// ----------------------------------------------------------------------------
+// Implementations
+
+type (
+	unknownVal struct{}
+	boolVal    bool
+	stringVal  string
+	int64Val   int64
+	intVal     struct{ val *big.Int }
+	floatVal   struct{ val *big.Rat }
+	complexVal struct{ re, im *big.Rat }
+)
+
+func (unknownVal) Kind() Kind { return Unknown }
+func (boolVal) Kind() Kind    { return Bool }
+func (stringVal) Kind() Kind  { return String }
+func (int64Val) Kind() Kind   { return Int }
+func (intVal) Kind() Kind     { return Int }
+func (floatVal) Kind() Kind   { return Float }
+func (complexVal) Kind() Kind { return Complex }
+
+func (unknownVal) String() string   { return "unknown" }
+func (x boolVal) String() string    { return fmt.Sprintf("%v", bool(x)) }
+func (x stringVal) String() string  { return strconv.Quote(string(x)) }
+func (x int64Val) String() string   { return strconv.FormatInt(int64(x), 10) }
+func (x intVal) String() string     { return x.val.String() }
+func (x floatVal) String() string   { return x.val.String() }
+func (x complexVal) String() string { return fmt.Sprintf("(%s + %si)", x.re, x.im) }
+
+func (unknownVal) implementsValue() {}
+func (boolVal) implementsValue()    {}
+func (stringVal) implementsValue()  {}
+func (int64Val) implementsValue()   {}
+func (intVal) implementsValue()     {}
+func (floatVal) implementsValue()   {}
+func (complexVal) implementsValue() {}
+
+// int64 bounds
+var (
+	minInt64 = big.NewInt(-1 << 63)
+	maxInt64 = big.NewInt(1<<63 - 1)
+)
+
+func normInt(x *big.Int) Value {
+	if minInt64.Cmp(x) <= 0 && x.Cmp(maxInt64) <= 0 {
+		return int64Val(x.Int64())
+	}
+	return intVal{x}
+}
+
+func normFloat(x *big.Rat) Value {
+	if x.IsInt() {
+		return normInt(x.Num())
+	}
+	return floatVal{x}
+}
+
+func normComplex(re, im *big.Rat) Value {
+	if im.Sign() == 0 {
+		return normFloat(re)
+	}
+	return complexVal{re, im}
+}
+
+// ----------------------------------------------------------------------------
+// Factories
+
+// MakeUnknown returns the Unknown value.
+func MakeUnknown() Value { return unknownVal{} }
+
+// MakeBool returns the Bool value for x.
+func MakeBool(b bool) Value { return boolVal(b) }
+
+// MakeString returns the String value for x.
+func MakeString(s string) Value { return stringVal(s) }
+
+// MakeInt64 returns the Int value for x.
+func MakeInt64(x int64) Value { return int64Val(x) }
+
+// MakeUint64 returns the Int value for x.
+func MakeUint64(x uint64) Value { return normInt(new(big.Int).SetUint64(x)) }
+
+// MakeFloat64 returns the numeric value for x.
+// If x is not finite, the result is unknown.
+func MakeFloat64(x float64) Value {
+	if f := new(big.Rat).SetFloat64(x); f != nil {
+		return normFloat(f)
+	}
+	return unknownVal{}
+}
+
+// MakeFromLiteral returns the corresponding integer, floating-point,
+// imaginary, character, or string value for a Go literal string.
+// If prec > 0, prec specifies an upper limit for the precision of
+// a numeric value. If the literal string is invalid, the result is
+// nil.
+// BUG(gri) Only prec == 0 is supported at the moment.
+func MakeFromLiteral(lit string, tok token.Token, prec uint) Value {
+	if prec != 0 {
+		panic("limited precision not supported")
+	}
+	switch tok {
+	case token.INT:
+		if x, err := strconv.ParseInt(lit, 0, 64); err == nil {
+			return int64Val(x)
+		}
+		if x, ok := new(big.Int).SetString(lit, 0); ok {
+			return intVal{x}
+		}
+
+	case token.FLOAT:
+		if x, ok := new(big.Rat).SetString(lit); ok {
+			return normFloat(x)
+		}
+
+	case token.IMAG:
+		if n := len(lit); n > 0 && lit[n-1] == 'i' {
+			if im, ok := new(big.Rat).SetString(lit[0 : n-1]); ok {
+				return normComplex(big.NewRat(0, 1), im)
+			}
+		}
+
+	case token.CHAR:
+		if n := len(lit); n >= 2 {
+			if code, _, _, err := strconv.UnquoteChar(lit[1:n-1], '\''); err == nil {
+				return int64Val(code)
+			}
+		}
+
+	case token.STRING:
+		if s, err := strconv.Unquote(lit); err == nil {
+			return stringVal(s)
+		}
+	}
+
+	return nil
+}
+
+// ----------------------------------------------------------------------------
+// Accessors
+//
+// For unknown arguments the result is the zero value for the respective
+// accessor type, except for Sign, where the result is 1.
+
+// BoolVal returns the Go boolean value of x, which must be a Bool or an Unknown.
+// If x is Unknown, the result is false.
+func BoolVal(x Value) bool {
+	switch x := x.(type) {
+	case boolVal:
+		return bool(x)
+	case unknownVal:
+		return false
+	}
+	panic(fmt.Sprintf("%v not a Bool", x))
+}
+
+// StringVal returns the Go string value of x, which must be a String or an Unknown.
+// If x is Unknown, the result is "".
+func StringVal(x Value) string {
+	switch x := x.(type) {
+	case stringVal:
+		return string(x)
+	case unknownVal:
+		return ""
+	}
+	panic(fmt.Sprintf("%v not a String", x))
+}
+
+// Int64Val returns the Go int64 value of x and whether the result is exact;
+// x must be an Int or an Unknown. If the result is not exact, its value is undefined.
+// If x is Unknown, the result is (0, false).
+func Int64Val(x Value) (int64, bool) {
+	switch x := x.(type) {
+	case int64Val:
+		return int64(x), true
+	case intVal:
+		return x.val.Int64(), x.val.BitLen() <= 63
+	case unknownVal:
+		return 0, false
+	}
+	panic(fmt.Sprintf("%v not an Int", x))
+}
+
+// Uint64Val returns the Go uint64 value of x and whether the result is exact;
+// x must be an Int or an Unknown. If the result is not exact, its value is undefined.
+// If x is Unknown, the result is (0, false).
+func Uint64Val(x Value) (uint64, bool) {
+	switch x := x.(type) {
+	case int64Val:
+		return uint64(x), x >= 0
+	case intVal:
+		return x.val.Uint64(), x.val.Sign() >= 0 && x.val.BitLen() <= 64
+	case unknownVal:
+		return 0, false
+	}
+	panic(fmt.Sprintf("%v not an Int", x))
+}
+
+// Float32Val is like Float64Val but for float32 instead of float64.
+func Float32Val(x Value) (float32, bool) {
+	switch x := x.(type) {
+	case int64Val:
+		f := float32(x)
+		return f, int64Val(f) == x
+	case intVal:
+		return ratToFloat32(new(big.Rat).SetFrac(x.val, int1))
+	case floatVal:
+		return ratToFloat32(x.val)
+	case unknownVal:
+		return 0, false
+	}
+	panic(fmt.Sprintf("%v not a Float", x))
+}
+
+// Float64Val returns the nearest Go float64 value of x and whether the result is exact;
+// x must be numeric but not Complex, or Unknown. For values too small (too close to 0)
+// to represent as float64, Float64Val silently underflows to 0. The result sign always
+// matches the sign of x, even for 0.
+// If x is Unknown, the result is (0, false).
+func Float64Val(x Value) (float64, bool) {
+	switch x := x.(type) {
+	case int64Val:
+		f := float64(int64(x))
+		return f, int64Val(f) == x
+	case intVal:
+		return new(big.Rat).SetFrac(x.val, int1).Float64()
+	case floatVal:
+		return x.val.Float64()
+	case unknownVal:
+		return 0, false
+	}
+	panic(fmt.Sprintf("%v not a Float", x))
+}
+
+// BitLen returns the number of bits required to represent
+// the absolute value x in binary representation; x must be an Int or an Unknown.
+// If x is Unknown, the result is 0.
+func BitLen(x Value) int {
+	switch x := x.(type) {
+	case int64Val:
+		return new(big.Int).SetInt64(int64(x)).BitLen()
+	case intVal:
+		return x.val.BitLen()
+	case unknownVal:
+		return 0
+	}
+	panic(fmt.Sprintf("%v not an Int", x))
+}
+
+// Sign returns -1, 0, or 1 depending on whether x < 0, x == 0, or x > 0;
+// x must be numeric or Unknown. For complex values x, the sign is 0 if x == 0,
+// otherwise it is != 0. If x is Unknown, the result is 1.
+func Sign(x Value) int {
+	switch x := x.(type) {
+	case int64Val:
+		switch {
+		case x < 0:
+			return -1
+		case x > 0:
+			return 1
+		}
+		return 0
+	case intVal:
+		return x.val.Sign()
+	case floatVal:
+		return x.val.Sign()
+	case complexVal:
+		return x.re.Sign() | x.im.Sign()
+	case unknownVal:
+		return 1 // avoid spurious division by zero errors
+	}
+	panic(fmt.Sprintf("%v not numeric", x))
+}
+
+// ----------------------------------------------------------------------------
+// Support for serializing/deserializing integers
+
+const (
+	// Compute the size of a Word in bytes.
+	_m       = ^big.Word(0)
+	_log     = _m>>8&1 + _m>>16&1 + _m>>32&1
+	wordSize = 1 << _log
+)
+
+// Bytes returns the bytes for the absolute value of x in little-
+// endian binary representation; x must be an Int.
+func Bytes(x Value) []byte {
+	var val *big.Int
+	switch x := x.(type) {
+	case int64Val:
+		val = new(big.Int).SetInt64(int64(x))
+	case intVal:
+		val = x.val
+	default:
+		panic(fmt.Sprintf("%v not an Int", x))
+	}
+
+	words := val.Bits()
+	bytes := make([]byte, len(words)*wordSize)
+
+	i := 0
+	for _, w := range words {
+		for j := 0; j < wordSize; j++ {
+			bytes[i] = byte(w)
+			w >>= 8
+			i++
+		}
+	}
+	// remove leading 0's
+	for i > 0 && bytes[i-1] == 0 {
+		i--
+	}
+
+	return bytes[:i]
+}
+
+// MakeFromBytes returns the Int value given the bytes of its little-endian
+// binary representation. An empty byte slice argument represents 0.
+func MakeFromBytes(bytes []byte) Value {
+	words := make([]big.Word, (len(bytes)+(wordSize-1))/wordSize)
+
+	i := 0
+	var w big.Word
+	var s uint
+	for _, b := range bytes {
+		w |= big.Word(b) << s
+		if s += 8; s == wordSize*8 {
+			words[i] = w
+			i++
+			w = 0
+			s = 0
+		}
+	}
+	// store last word
+	if i < len(words) {
+		words[i] = w
+		i++
+	}
+	// remove leading 0's
+	for i > 0 && words[i-1] == 0 {
+		i--
+	}
+
+	return normInt(new(big.Int).SetBits(words[:i]))
+}
+
+// ----------------------------------------------------------------------------
+// Support for disassembling fractions
+
+// Num returns the numerator of x; x must be Int, Float, or Unknown.
+// If x is Unknown, the result is Unknown, otherwise it is an Int
+// with the same sign as x.
+func Num(x Value) Value {
+	switch x := x.(type) {
+	case unknownVal, int64Val, intVal:
+		return x
+	case floatVal:
+		return normInt(x.val.Num())
+	}
+	panic(fmt.Sprintf("%v not Int or Float", x))
+}
+
+// Denom returns the denominator of x; x must be Int, Float, or Unknown.
+// If x is Unknown, the result is Unknown, otherwise it is an Int >= 1.
+func Denom(x Value) Value {
+	switch x := x.(type) {
+	case unknownVal:
+		return x
+	case int64Val, intVal:
+		return int64Val(1)
+	case floatVal:
+		return normInt(x.val.Denom())
+	}
+	panic(fmt.Sprintf("%v not Int or Float", x))
+}
+
+// ----------------------------------------------------------------------------
+// Support for assembling/disassembling complex numbers
+
+// MakeImag returns the numeric value x*i (possibly 0);
+// x must be Int, Float, or Unknown.
+// If x is Unknown, the result is Unknown.
+func MakeImag(x Value) Value {
+	var im *big.Rat
+	switch x := x.(type) {
+	case unknownVal:
+		return x
+	case int64Val:
+		im = big.NewRat(int64(x), 1)
+	case intVal:
+		im = new(big.Rat).SetFrac(x.val, int1)
+	case floatVal:
+		im = x.val
+	default:
+		panic(fmt.Sprintf("%v not Int or Float", x))
+	}
+	return normComplex(rat0, im)
+}
+
+// Real returns the real part of x, which must be a numeric or unknown value.
+// If x is Unknown, the result is Unknown.
+func Real(x Value) Value {
+	switch x := x.(type) {
+	case unknownVal, int64Val, intVal, floatVal:
+		return x
+	case complexVal:
+		return normFloat(x.re)
+	}
+	panic(fmt.Sprintf("%v not numeric", x))
+}
+
+// Imag returns the imaginary part of x, which must be a numeric or unknown value.
+// If x is Unknown, the result is Unknown.
+func Imag(x Value) Value {
+	switch x := x.(type) {
+	case unknownVal:
+		return x
+	case int64Val, intVal, floatVal:
+		return int64Val(0)
+	case complexVal:
+		return normFloat(x.im)
+	}
+	panic(fmt.Sprintf("%v not numeric", x))
+}
+
+// ----------------------------------------------------------------------------
+// Operations
+
+// is32bit reports whether x can be represented using 32 bits.
+func is32bit(x int64) bool {
+	const s = 32
+	return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+}
+
+// is63bit reports whether x can be represented using 63 bits.
+func is63bit(x int64) bool {
+	const s = 63
+	return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+}
+
+// UnaryOp returns the result of the unary expression op y.
+// The operation must be defined for the operand.
+// If prec > 0 it specifies the ^ (xor) result size in bits.
+// If y is Unknown, the result is Unknown.
+//
+func UnaryOp(op token.Token, y Value, prec uint) Value {
+	switch op {
+	case token.ADD:
+		switch y.(type) {
+		case unknownVal, int64Val, intVal, floatVal, complexVal:
+			return y
+		}
+
+	case token.SUB:
+		switch y := y.(type) {
+		case unknownVal:
+			return y
+		case int64Val:
+			if z := -y; z != y {
+				return z // no overflow
+			}
+			return normInt(new(big.Int).Neg(big.NewInt(int64(y))))
+		case intVal:
+			return normInt(new(big.Int).Neg(y.val))
+		case floatVal:
+			return normFloat(new(big.Rat).Neg(y.val))
+		case complexVal:
+			return normComplex(new(big.Rat).Neg(y.re), new(big.Rat).Neg(y.im))
+		}
+
+	case token.XOR:
+		var z big.Int
+		switch y := y.(type) {
+		case unknownVal:
+			return y
+		case int64Val:
+			z.Not(big.NewInt(int64(y)))
+		case intVal:
+			z.Not(y.val)
+		default:
+			goto Error
+		}
+		// For unsigned types, the result will be negative and
+		// thus "too large": We must limit the result precision
+		// to the type's precision.
+		if prec > 0 {
+			z.AndNot(&z, new(big.Int).Lsh(big.NewInt(-1), prec)) // z &^= (-1)<<prec
+		}
+		return normInt(&z)
+
+	case token.NOT:
+		switch y := y.(type) {
+		case unknownVal:
+			return y
+		case boolVal:
+			return !y
+		}
+	}
+
+Error:
+	panic(fmt.Sprintf("invalid unary operation %s%v", op, y))
+}
+
+var (
+	int1 = big.NewInt(1)
+	rat0 = big.NewRat(0, 1)
+)
+
+func ord(x Value) int {
+	switch x.(type) {
+	default:
+		return 0
+	case boolVal, stringVal:
+		return 1
+	case int64Val:
+		return 2
+	case intVal:
+		return 3
+	case floatVal:
+		return 4
+	case complexVal:
+		return 5
+	}
+}
+
+// match returns the matching representation (same type) with the
+// smallest complexity for two values x and y. If one of them is
+// numeric, both of them must be numeric. If one of them is Unknown,
+// both results are Unknown.
+//
+func match(x, y Value) (_, _ Value) {
+	if ord(x) > ord(y) {
+		y, x = match(y, x)
+		return x, y
+	}
+	// ord(x) <= ord(y)
+
+	switch x := x.(type) {
+	case unknownVal:
+		return x, x
+
+	case boolVal, stringVal, complexVal:
+		return x, y
+
+	case int64Val:
+		switch y := y.(type) {
+		case int64Val:
+			return x, y
+		case intVal:
+			return intVal{big.NewInt(int64(x))}, y
+		case floatVal:
+			return floatVal{big.NewRat(int64(x), 1)}, y
+		case complexVal:
+			return complexVal{big.NewRat(int64(x), 1), rat0}, y
+		}
+
+	case intVal:
+		switch y := y.(type) {
+		case intVal:
+			return x, y
+		case floatVal:
+			return floatVal{new(big.Rat).SetFrac(x.val, int1)}, y
+		case complexVal:
+			return complexVal{new(big.Rat).SetFrac(x.val, int1), rat0}, y
+		}
+
+	case floatVal:
+		switch y := y.(type) {
+		case floatVal:
+			return x, y
+		case complexVal:
+			return complexVal{x.val, rat0}, y
+		}
+	}
+
+	panic("unreachable")
+}
+
+// BinaryOp returns the result of the binary expression x op y.
+// The operation must be defined for the operands. If one of the
+// operands is Unknown, the result is Unknown.
+// To force integer division of Int operands, use op == token.QUO_ASSIGN
+// instead of token.QUO; the result is guaranteed to be Int in this case.
+// Division by zero leads to a run-time panic.
+//
+func BinaryOp(x Value, op token.Token, y Value) Value {
+	x, y = match(x, y)
+
+	switch x := x.(type) {
+	case unknownVal:
+		return x
+
+	case boolVal:
+		y := y.(boolVal)
+		switch op {
+		case token.LAND:
+			return x && y
+		case token.LOR:
+			return x || y
+		}
+
+	case int64Val:
+		a := int64(x)
+		b := int64(y.(int64Val))
+		var c int64
+		switch op {
+		case token.ADD:
+			if !is63bit(a) || !is63bit(b) {
+				return normInt(new(big.Int).Add(big.NewInt(a), big.NewInt(b)))
+			}
+			c = a + b
+		case token.SUB:
+			if !is63bit(a) || !is63bit(b) {
+				return normInt(new(big.Int).Sub(big.NewInt(a), big.NewInt(b)))
+			}
+			c = a - b
+		case token.MUL:
+			if !is32bit(a) || !is32bit(b) {
+				return normInt(new(big.Int).Mul(big.NewInt(a), big.NewInt(b)))
+			}
+			c = a * b
+		case token.QUO:
+			return normFloat(new(big.Rat).SetFrac(big.NewInt(a), big.NewInt(b)))
+		case token.QUO_ASSIGN: // force integer division
+			c = a / b
+		case token.REM:
+			c = a % b
+		case token.AND:
+			c = a & b
+		case token.OR:
+			c = a | b
+		case token.XOR:
+			c = a ^ b
+		case token.AND_NOT:
+			c = a &^ b
+		default:
+			goto Error
+		}
+		return int64Val(c)
+
+	case intVal:
+		a := x.val
+		b := y.(intVal).val
+		var c big.Int
+		switch op {
+		case token.ADD:
+			c.Add(a, b)
+		case token.SUB:
+			c.Sub(a, b)
+		case token.MUL:
+			c.Mul(a, b)
+		case token.QUO:
+			return normFloat(new(big.Rat).SetFrac(a, b))
+		case token.QUO_ASSIGN: // force integer division
+			c.Quo(a, b)
+		case token.REM:
+			c.Rem(a, b)
+		case token.AND:
+			c.And(a, b)
+		case token.OR:
+			c.Or(a, b)
+		case token.XOR:
+			c.Xor(a, b)
+		case token.AND_NOT:
+			c.AndNot(a, b)
+		default:
+			goto Error
+		}
+		return normInt(&c)
+
+	case floatVal:
+		a := x.val
+		b := y.(floatVal).val
+		var c big.Rat
+		switch op {
+		case token.ADD:
+			c.Add(a, b)
+		case token.SUB:
+			c.Sub(a, b)
+		case token.MUL:
+			c.Mul(a, b)
+		case token.QUO:
+			c.Quo(a, b)
+		default:
+			goto Error
+		}
+		return normFloat(&c)
+
+	case complexVal:
+		y := y.(complexVal)
+		a, b := x.re, x.im
+		c, d := y.re, y.im
+		var re, im big.Rat
+		switch op {
+		case token.ADD:
+			// (a+c) + i(b+d)
+			re.Add(a, c)
+			im.Add(b, d)
+		case token.SUB:
+			// (a-c) + i(b-d)
+			re.Sub(a, c)
+			im.Sub(b, d)
+		case token.MUL:
+			// (ac-bd) + i(bc+ad)
+			var ac, bd, bc, ad big.Rat
+			ac.Mul(a, c)
+			bd.Mul(b, d)
+			bc.Mul(b, c)
+			ad.Mul(a, d)
+			re.Sub(&ac, &bd)
+			im.Add(&bc, &ad)
+		case token.QUO:
+			// (ac+bd)/s + i(bc-ad)/s, with s = cc + dd
+			var ac, bd, bc, ad, s, cc, dd big.Rat
+			ac.Mul(a, c)
+			bd.Mul(b, d)
+			bc.Mul(b, c)
+			ad.Mul(a, d)
+			cc.Mul(c, c)
+			dd.Mul(d, d)
+			s.Add(&cc, &dd)
+			re.Add(&ac, &bd)
+			re.Quo(&re, &s)
+			im.Sub(&bc, &ad)
+			im.Quo(&im, &s)
+		default:
+			goto Error
+		}
+		return normComplex(&re, &im)
+
+	case stringVal:
+		if op == token.ADD {
+			return x + y.(stringVal)
+		}
+	}
+
+Error:
+	panic(fmt.Sprintf("invalid binary operation %v %s %v", x, op, y))
+}
+
+// Shift returns the result of the shift expression x op s
+// with op == token.SHL or token.SHR (<< or >>). x must be
+// an Int or an Unknown. If x is Unknown, the result is x.
+//
+func Shift(x Value, op token.Token, s uint) Value {
+	switch x := x.(type) {
+	case unknownVal:
+		return x
+
+	case int64Val:
+		if s == 0 {
+			return x
+		}
+		switch op {
+		case token.SHL:
+			z := big.NewInt(int64(x))
+			return normInt(z.Lsh(z, s))
+		case token.SHR:
+			return x >> s
+		}
+
+	case intVal:
+		if s == 0 {
+			return x
+		}
+		var z big.Int
+		switch op {
+		case token.SHL:
+			return normInt(z.Lsh(x.val, s))
+		case token.SHR:
+			return normInt(z.Rsh(x.val, s))
+		}
+	}
+
+	panic(fmt.Sprintf("invalid shift %v %s %d", x, op, s))
+}
+
+func cmpZero(x int, op token.Token) bool {
+	switch op {
+	case token.EQL:
+		return x == 0
+	case token.NEQ:
+		return x != 0
+	case token.LSS:
+		return x < 0
+	case token.LEQ:
+		return x <= 0
+	case token.GTR:
+		return x > 0
+	case token.GEQ:
+		return x >= 0
+	}
+	panic("unreachable")
+}
+
+// Compare returns the result of the comparison x op y.
+// The comparison must be defined for the operands.
+// If one of the operands is Unknown, the result is
+// false.
+//
+func Compare(x Value, op token.Token, y Value) bool {
+	x, y = match(x, y)
+
+	switch x := x.(type) {
+	case unknownVal:
+		return false
+
+	case boolVal:
+		y := y.(boolVal)
+		switch op {
+		case token.EQL:
+			return x == y
+		case token.NEQ:
+			return x != y
+		}
+
+	case int64Val:
+		y := y.(int64Val)
+		switch op {
+		case token.EQL:
+			return x == y
+		case token.NEQ:
+			return x != y
+		case token.LSS:
+			return x < y
+		case token.LEQ:
+			return x <= y
+		case token.GTR:
+			return x > y
+		case token.GEQ:
+			return x >= y
+		}
+
+	case intVal:
+		return cmpZero(x.val.Cmp(y.(intVal).val), op)
+
+	case floatVal:
+		return cmpZero(x.val.Cmp(y.(floatVal).val), op)
+
+	case complexVal:
+		y := y.(complexVal)
+		re := x.re.Cmp(y.re)
+		im := x.im.Cmp(y.im)
+		switch op {
+		case token.EQL:
+			return re == 0 && im == 0
+		case token.NEQ:
+			return re != 0 || im != 0
+		}
+
+	case stringVal:
+		y := y.(stringVal)
+		switch op {
+		case token.EQL:
+			return x == y
+		case token.NEQ:
+			return x != y
+		case token.LSS:
+			return x < y
+		case token.LEQ:
+			return x <= y
+		case token.GTR:
+			return x > y
+		case token.GEQ:
+			return x >= y
+		}
+	}
+
+	panic(fmt.Sprintf("invalid comparison %v %s %v", x, op, y))
+}
diff --git a/libgo/go/go/constant/value_test.go b/libgo/go/go/constant/value_test.go
new file mode 100644
index 00000000000..08cdd5e625c
--- /dev/null
+++ b/libgo/go/go/constant/value_test.go
@@ -0,0 +1,375 @@
+// Copyright 2013 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 constant
+
+import (
+	"go/token"
+	"strings"
+	"testing"
+)
+
+// TODO(gri) expand this test framework
+
+var opTests = []string{
+	// unary operations
+	`+ 0 = 0`,
+	`+ ? = ?`,
+	`- 1 = -1`,
+	`- ? = ?`,
+	`^ 0 = -1`,
+	`^ ? = ?`,
+
+	`! true = false`,
+	`! false = true`,
+	`! ? = ?`,
+
+	// etc.
+
+	// binary operations
+	`"" + "" = ""`,
+	`"foo" + "" = "foo"`,
+	`"" + "bar" = "bar"`,
+	`"foo" + "bar" = "foobar"`,
+
+	`0 + 0 = 0`,
+	`0 + 0.1 = 0.1`,
+	`0 + 0.1i = 0.1i`,
+	`0.1 + 0.9 = 1`,
+	`1e100 + 1e100 = 2e100`,
+	`? + 0 = ?`,
+	`0 + ? = ?`,
+
+	`0 - 0 = 0`,
+	`0 - 0.1 = -0.1`,
+	`0 - 0.1i = -0.1i`,
+	`1e100 - 1e100 = 0`,
+	`? - 0 = ?`,
+	`0 - ? = ?`,
+
+	`0 * 0 = 0`,
+	`1 * 0.1 = 0.1`,
+	`1 * 0.1i = 0.1i`,
+	`1i * 1i = -1`,
+	`? * 0 = ?`,
+	`0 * ? = ?`,
+
+	`0 / 0 = "division_by_zero"`,
+	`10 / 2 = 5`,
+	`5 / 3 = 5/3`,
+	`5i / 3i = 5/3`,
+	`? / 0 = ?`,
+	`0 / ? = ?`,
+
+	`0 % 0 = "runtime_error:_integer_divide_by_zero"`, // TODO(gri) should be the same as for /
+	`10 % 3 = 1`,
+	`? % 0 = ?`,
+	`0 % ? = ?`,
+
+	`0 & 0 = 0`,
+	`12345 & 0 = 0`,
+	`0xff & 0xf = 0xf`,
+	`? & 0 = ?`,
+	`0 & ? = ?`,
+
+	`0 | 0 = 0`,
+	`12345 | 0 = 12345`,
+	`0xb | 0xa0 = 0xab`,
+	`? | 0 = ?`,
+	`0 | ? = ?`,
+
+	`0 ^ 0 = 0`,
+	`1 ^ -1 = -2`,
+	`? ^ 0 = ?`,
+	`0 ^ ? = ?`,
+
+	`0 &^ 0 = 0`,
+	`0xf &^ 1 = 0xe`,
+	`1 &^ 0xf = 0`,
+	// etc.
+
+	// shifts
+	`0 << 0 = 0`,
+	`1 << 10 = 1024`,
+	`0 >> 0 = 0`,
+	`1024 >> 10 == 1`,
+	`? << 0 == ?`,
+	`? >> 10 == ?`,
+	// etc.
+
+	// comparisons
+	`false == false = true`,
+	`false == true = false`,
+	`true == false = false`,
+	`true == true = true`,
+
+	`false != false = false`,
+	`false != true = true`,
+	`true != false = true`,
+	`true != true = false`,
+
+	`"foo" == "bar" = false`,
+	`"foo" != "bar" = true`,
+	`"foo" < "bar" = false`,
+	`"foo" <= "bar" = false`,
+	`"foo" > "bar" = true`,
+	`"foo" >= "bar" = true`,
+
+	`0 == 0 = true`,
+	`0 != 0 = false`,
+	`0 < 10 = true`,
+	`10 <= 10 = true`,
+	`0 > 10 = false`,
+	`10 >= 10 = true`,
+
+	`1/123456789 == 1/123456789 == true`,
+	`1/123456789 != 1/123456789 == false`,
+	`1/123456789 < 1/123456788 == true`,
+	`1/123456788 <= 1/123456789 == false`,
+	`0.11 > 0.11 = false`,
+	`0.11 >= 0.11 = true`,
+
+	`? == 0 = false`,
+	`? != 0 = false`,
+	`? < 10 = false`,
+	`? <= 10 = false`,
+	`? > 10 = false`,
+	`? >= 10 = false`,
+
+	`0 == ? = false`,
+	`0 != ? = false`,
+	`0 < ? = false`,
+	`10 <= ? = false`,
+	`0 > ? = false`,
+	`10 >= ? = false`,
+
+	// etc.
+}
+
+func TestOps(t *testing.T) {
+	for _, test := range opTests {
+		a := strings.Split(test, " ")
+		i := 0 // operator index
+
+		var x, x0 Value
+		switch len(a) {
+		case 4:
+			// unary operation
+		case 5:
+			// binary operation
+			x, x0 = val(a[0]), val(a[0])
+			i = 1
+		default:
+			t.Errorf("invalid test case: %s", test)
+			continue
+		}
+
+		op, ok := optab[a[i]]
+		if !ok {
+			panic("missing optab entry for " + a[i])
+		}
+
+		y, y0 := val(a[i+1]), val(a[i+1])
+
+		got := doOp(x, op, y)
+		want := val(a[i+3])
+		if !eql(got, want) {
+			t.Errorf("%s: got %s; want %s", test, got, want)
+		}
+		if x0 != nil && !eql(x, x0) {
+			t.Errorf("%s: x changed to %s", test, x)
+		}
+		if !eql(y, y0) {
+			t.Errorf("%s: y changed to %s", test, y)
+		}
+	}
+}
+
+func eql(x, y Value) bool {
+	_, ux := x.(unknownVal)
+	_, uy := y.(unknownVal)
+	if ux || uy {
+		return ux == uy
+	}
+	return Compare(x, token.EQL, y)
+}
+
+// ----------------------------------------------------------------------------
+// Support functions
+
+func val(lit string) Value {
+	if len(lit) == 0 {
+		return MakeUnknown()
+	}
+
+	switch lit {
+	case "?":
+		return MakeUnknown()
+	case "true":
+		return MakeBool(true)
+	case "false":
+		return MakeBool(false)
+	}
+
+	tok := token.INT
+	switch first, last := lit[0], lit[len(lit)-1]; {
+	case first == '"' || first == '`':
+		tok = token.STRING
+		lit = strings.Replace(lit, "_", " ", -1)
+	case first == '\'':
+		tok = token.CHAR
+	case last == 'i':
+		tok = token.IMAG
+	default:
+		if !strings.HasPrefix(lit, "0x") && strings.ContainsAny(lit, "./Ee") {
+			tok = token.FLOAT
+		}
+	}
+
+	return MakeFromLiteral(lit, tok, 0)
+}
+
+var optab = map[string]token.Token{
+	"!": token.NOT,
+
+	"+": token.ADD,
+	"-": token.SUB,
+	"*": token.MUL,
+	"/": token.QUO,
+	"%": token.REM,
+
+	"<<": token.SHL,
+	">>": token.SHR,
+
+	"&":  token.AND,
+	"|":  token.OR,
+	"^":  token.XOR,
+	"&^": token.AND_NOT,
+
+	"==": token.EQL,
+	"!=": token.NEQ,
+	"<":  token.LSS,
+	"<=": token.LEQ,
+	">":  token.GTR,
+	">=": token.GEQ,
+}
+
+func panicHandler(v *Value) {
+	switch p := recover().(type) {
+	case nil:
+		// nothing to do
+	case string:
+		*v = MakeString(p)
+	case error:
+		*v = MakeString(p.Error())
+	default:
+		panic(p)
+	}
+}
+
+func doOp(x Value, op token.Token, y Value) (z Value) {
+	defer panicHandler(&z)
+
+	if x == nil {
+		return UnaryOp(op, y, 0)
+	}
+
+	switch op {
+	case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
+		return MakeBool(Compare(x, op, y))
+	case token.SHL, token.SHR:
+		s, _ := Int64Val(y)
+		return Shift(x, op, uint(s))
+	default:
+		return BinaryOp(x, op, y)
+	}
+}
+
+// ----------------------------------------------------------------------------
+// Other tests
+
+var fracTests = []string{
+	"0 0 1",
+	"1 1 1",
+	"-1 -1 1",
+	"1.2 6 5",
+	"-0.991 -991 1000",
+	"1e100 1e100 1",
+}
+
+func TestFractions(t *testing.T) {
+	for _, test := range fracTests {
+		a := strings.Split(test, " ")
+		if len(a) != 3 {
+			t.Errorf("invalid test case: %s", test)
+			continue
+		}
+
+		x := val(a[0])
+		n := val(a[1])
+		d := val(a[2])
+
+		if got := Num(x); !eql(got, n) {
+			t.Errorf("%s: got num = %s; want %s", test, got, n)
+		}
+
+		if got := Denom(x); !eql(got, d) {
+			t.Errorf("%s: got denom = %s; want %s", test, got, d)
+		}
+	}
+}
+
+var bytesTests = []string{
+	"0",
+	"1",
+	"123456789",
+	"123456789012345678901234567890123456789012345678901234567890",
+}
+
+func TestBytes(t *testing.T) {
+	for _, test := range bytesTests {
+		x := val(test)
+		bytes := Bytes(x)
+
+		// special case 0
+		if Sign(x) == 0 && len(bytes) != 0 {
+			t.Errorf("%s: got %v; want empty byte slice", test, bytes)
+		}
+
+		if n := len(bytes); n > 0 && bytes[n-1] == 0 {
+			t.Errorf("%s: got %v; want no leading 0 byte", test, bytes)
+		}
+
+		if got := MakeFromBytes(bytes); !eql(got, x) {
+			t.Errorf("%s: got %s; want %s (bytes = %v)", test, got, x, bytes)
+		}
+	}
+}
+
+func TestUnknown(t *testing.T) {
+	u := MakeUnknown()
+	var values = []Value{
+		u,
+		MakeBool(false), // token.ADD ok below, operation is never considered
+		MakeString(""),
+		MakeInt64(1),
+		MakeFromLiteral("-1234567890123456789012345678901234567890", token.INT, 0),
+		MakeFloat64(1.2),
+		MakeImag(MakeFloat64(1.2)),
+	}
+	for _, val := range values {
+		x, y := val, u
+		for i := range [2]int{} {
+			if i == 1 {
+				x, y = y, x
+			}
+			if got := BinaryOp(x, token.ADD, y); got.Kind() != Unknown {
+				t.Errorf("%s + %s: got %s; want %s", x, y, got, u)
+			}
+			if got := Compare(x, token.EQL, y); got {
+				t.Errorf("%s == %s: got true; want false", x, y)
+			}
+		}
+	}
+}
diff --git a/libgo/go/go/doc/doc.go b/libgo/go/go/doc/doc.go
index 4264940a0cd..3c3e28d48fb 100644
--- a/libgo/go/go/doc/doc.go
+++ b/libgo/go/go/doc/doc.go
@@ -18,7 +18,8 @@ type Package struct {
 	Imports    []string
 	Filenames  []string
 	Notes      map[string][]*Note
-	// DEPRECATED. For backward compatibility Bugs is still populated,
+
+	// Deprecated: For backward compatibility Bugs is still populated,
 	// but all new code should use Notes instead.
 	Bugs []string
 
diff --git a/libgo/go/go/doc/exports.go b/libgo/go/go/doc/exports.go
index 1d3b466d8c7..4a12b1e55f8 100644
--- a/libgo/go/go/doc/exports.go
+++ b/libgo/go/go/doc/exports.go
@@ -12,13 +12,12 @@ import (
 )
 
 // filterIdentList removes unexported names from list in place
-// and returns the resulting list. If blankOk is set, blank
-// identifiers are considered exported names.
+// and returns the resulting list.
 //
-func filterIdentList(list []*ast.Ident, blankOk bool) []*ast.Ident {
+func filterIdentList(list []*ast.Ident) []*ast.Ident {
 	j := 0
 	for _, x := range list {
-		if ast.IsExported(x.Name) || (blankOk && x.Name == "_") {
+		if ast.IsExported(x.Name) {
 			list[j] = x
 			j++
 		}
@@ -26,6 +25,17 @@ func filterIdentList(list []*ast.Ident, blankOk bool) []*ast.Ident {
 	return list[0:j]
 }
 
+// hasExportedName reports whether list contains any exported names.
+//
+func hasExportedName(list []*ast.Ident) bool {
+	for _, x := range list {
+		if x.IsExported() {
+			return true
+		}
+	}
+	return false
+}
+
 // removeErrorField removes anonymous fields named "error" from an interface.
 // This is called when "error" has been determined to be a local name,
 // not the predeclared type.
@@ -53,7 +63,7 @@ func removeErrorField(ityp *ast.InterfaceType) {
 }
 
 // filterFieldList removes unexported fields (field names) from the field list
-// in place and returns true if fields were removed. Anonymous fields are
+// in place and reports whether fields were removed. Anonymous fields are
 // recorded with the parent type. filterType is called with the types of
 // all remaining fields.
 //
@@ -78,7 +88,7 @@ func (r *reader) filterFieldList(parent *namedType, fields *ast.FieldList, ityp
 				r.remember(ityp)
 			}
 		} else {
-			field.Names = filterIdentList(field.Names, false)
+			field.Names = filterIdentList(field.Names)
 			if len(field.Names) < n {
 				removedFields = true
 			}
@@ -146,9 +156,7 @@ func (r *reader) filterSpec(spec ast.Spec, tok token.Token) bool {
 		// always keep imports so we can collect them
 		return true
 	case *ast.ValueSpec:
-		// special case: consider blank constants as exported
-		// (work-around for issue 5397)
-		s.Names = filterIdentList(s.Names, tok == token.CONST)
+		s.Names = filterIdentList(s.Names)
 		if len(s.Names) > 0 {
 			r.filterType(nil, s.Type)
 			return true
@@ -165,7 +173,46 @@ func (r *reader) filterSpec(spec ast.Spec, tok token.Token) bool {
 	return false
 }
 
+// copyConstType returns a copy of typ with position pos.
+// typ must be a valid constant type.
+// In practice, only (possibly qualified) identifiers are possible.
+//
+func copyConstType(typ ast.Expr, pos token.Pos) ast.Expr {
+	switch typ := typ.(type) {
+	case *ast.Ident:
+		return &ast.Ident{Name: typ.Name, NamePos: pos}
+	case *ast.SelectorExpr:
+		if id, ok := typ.X.(*ast.Ident); ok {
+			// presumably a qualified identifier
+			return &ast.SelectorExpr{
+				Sel: ast.NewIdent(typ.Sel.Name),
+				X:   &ast.Ident{Name: id.Name, NamePos: pos},
+			}
+		}
+	}
+	return nil // shouldn't happen, but be conservative and don't panic
+}
+
 func (r *reader) filterSpecList(list []ast.Spec, tok token.Token) []ast.Spec {
+	if tok == token.CONST {
+		// Propagate any type information that would get lost otherwise
+		// when unexported constants are filtered.
+		var prevType ast.Expr
+		for _, spec := range list {
+			spec := spec.(*ast.ValueSpec)
+			if spec.Type == nil && prevType != nil {
+				// provide current spec with an explicit type
+				spec.Type = copyConstType(prevType, spec.Pos())
+			}
+			if hasExportedName(spec.Names) {
+				// exported names are preserved so there's no need to propagate the type
+				prevType = nil
+			} else {
+				prevType = spec.Type
+			}
+		}
+	}
+
 	j := 0
 	for _, s := range list {
 		if r.filterSpec(s, tok) {
diff --git a/libgo/go/go/doc/testdata/blank.0.golden b/libgo/go/go/doc/testdata/blank.0.golden
index dae3ab2affa..c2987cf140e 100644
--- a/libgo/go/go/doc/testdata/blank.0.golden
+++ b/libgo/go/go/doc/testdata/blank.0.golden
@@ -4,14 +4,33 @@ PACKAGE blank
 IMPORTPATH
 	testdata/blank
 
+IMPORTS
+	os
+
 FILENAMES
 	testdata/blank.go
 
 CONSTANTS
+	// T constants counting from unexported constants. 
+	const (
+		C1	T
+		C2
+	
+		C3
+	
+		C4	int
+	)
+
+	// Constants with an imported type that needs to be propagated. 
+	const (
+		Default		os.FileMode	= 0644
+		Useless				= 0312
+		WideOpen			= 0777
+	)
+
 	// Package constants. 
 	const (
-		_	int	= iota
-		I1
+		I1	int
 		I2
 	)
 
@@ -28,10 +47,9 @@ TYPES
 	// 
 	type T int
 
-	// T constants. 
+	// T constants counting from a blank constant. 
 	const (
-		_	T	= iota
-		T1
+		T1	T
 		T2
 	)
 
diff --git a/libgo/go/go/doc/testdata/blank.1.golden b/libgo/go/go/doc/testdata/blank.1.golden
index 333d7e5b040..ee5054a4ed6 100644
--- a/libgo/go/go/doc/testdata/blank.1.golden
+++ b/libgo/go/go/doc/testdata/blank.1.golden
@@ -4,10 +4,25 @@ PACKAGE blank
 IMPORTPATH
 	testdata/blank
 
+IMPORTS
+	os
+
 FILENAMES
 	testdata/blank.go
 
 CONSTANTS
+	// T constants counting from unexported constants. 
+	const (
+		tweedledee	T	= iota
+		tweedledum
+		C1
+		C2
+		alice
+		C3
+		redQueen	int	= iota
+		C4
+	)
+
 	// Package constants. 
 	const (
 		_	int	= iota
@@ -15,6 +30,20 @@ CONSTANTS
 		I2
 	)
 
+	// Constants with an imported type that needs to be propagated. 
+	const (
+		zero		os.FileMode	= 0
+		Default				= 0644
+		Useless				= 0312
+		WideOpen			= 0777
+	)
+
+	// Unexported constants counting from blank iota. See issue 9615. 
+	const (
+		_	= iota
+		one	= iota + 1
+	)
+
 
 VARIABLES
 	// 
@@ -37,7 +66,7 @@ TYPES
 	// 
 	type T int
 
-	// T constants. 
+	// T constants counting from a blank constant. 
 	const (
 		_	T	= iota
 		T1
diff --git a/libgo/go/go/doc/testdata/blank.2.golden b/libgo/go/go/doc/testdata/blank.2.golden
index dae3ab2affa..c2987cf140e 100644
--- a/libgo/go/go/doc/testdata/blank.2.golden
+++ b/libgo/go/go/doc/testdata/blank.2.golden
@@ -4,14 +4,33 @@ PACKAGE blank
 IMPORTPATH
 	testdata/blank
 
+IMPORTS
+	os
+
 FILENAMES
 	testdata/blank.go
 
 CONSTANTS
+	// T constants counting from unexported constants. 
+	const (
+		C1	T
+		C2
+	
+		C3
+	
+		C4	int
+	)
+
+	// Constants with an imported type that needs to be propagated. 
+	const (
+		Default		os.FileMode	= 0644
+		Useless				= 0312
+		WideOpen			= 0777
+	)
+
 	// Package constants. 
 	const (
-		_	int	= iota
-		I1
+		I1	int
 		I2
 	)
 
@@ -28,10 +47,9 @@ TYPES
 	// 
 	type T int
 
-	// T constants. 
+	// T constants counting from a blank constant. 
 	const (
-		_	T	= iota
-		T1
+		T1	T
 		T2
 	)
 
diff --git a/libgo/go/go/doc/testdata/blank.go b/libgo/go/go/doc/testdata/blank.go
index f812c77b777..419a78f7d51 100644
--- a/libgo/go/go/doc/testdata/blank.go
+++ b/libgo/go/go/doc/testdata/blank.go
@@ -6,15 +6,37 @@
 // See issue 5397.
 package blank
 
+import "os"
+
 type T int
 
-// T constants.
+// T constants counting from a blank constant.
 const (
 	_ T = iota
 	T1
 	T2
 )
 
+// T constants counting from unexported constants.
+const (
+	tweedledee T = iota
+	tweedledum
+	C1
+	C2
+	alice
+	C3
+	redQueen int = iota
+	C4
+)
+
+// Constants with an imported type that needs to be propagated.
+const (
+	zero     os.FileMode = 0
+	Default              = 0644
+	Useless              = 0312
+	WideOpen             = 0777
+)
+
 // Package constants.
 const (
 	_ int = iota
@@ -22,6 +44,13 @@ const (
 	I2
 )
 
+// Unexported constants counting from blank iota.
+// See issue 9615.
+const (
+	_   = iota
+	one = iota + 1
+)
+
 // Blanks not in doc output:
 
 // S has a padding field.
diff --git a/libgo/go/go/format/format.go b/libgo/go/go/format/format.go
index 668a42df2df..1adfd7d45e8 100644
--- a/libgo/go/go/format/format.go
+++ b/libgo/go/go/format/format.go
@@ -12,8 +12,8 @@ import (
 	"go/parser"
 	"go/printer"
 	"go/token"
+	"internal/format"
 	"io"
-	"strings"
 )
 
 var config = printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 8}
@@ -82,7 +82,7 @@ func Node(dst io.Writer, fset *token.FileSet, node interface{}) error {
 //
 func Source(src []byte) ([]byte, error) {
 	fset := token.NewFileSet()
-	file, sourceAdj, indentAdj, err := parse(fset, "", src, true)
+	file, sourceAdj, indentAdj, err := format.Parse(fset, "", src, true)
 	if err != nil {
 		return nil, err
 	}
@@ -93,7 +93,7 @@ func Source(src []byte) ([]byte, error) {
 		ast.SortImports(fset, file)
 	}
 
-	return format(fset, file, sourceAdj, indentAdj, src, config)
+	return format.Format(fset, file, sourceAdj, indentAdj, src, config)
 }
 
 func hasUnsortedImports(file *ast.File) bool {
@@ -113,154 +113,3 @@ func hasUnsortedImports(file *ast.File) bool {
 	}
 	return false
 }
-
-// ----------------------------------------------------------------------------
-// Support functions
-//
-// The functions parse, format, and isSpace below are identical to the
-// respective functions in cmd/gofmt/gofmt.go - keep them in sync!
-//
-// TODO(gri) Factor out this functionality, eventually.
-
-// parse parses src, which was read from the named file,
-// as a Go source file, declaration, or statement list.
-func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
-	file *ast.File,
-	sourceAdj func(src []byte, indent int) []byte,
-	indentAdj int,
-	err error,
-) {
-	// Try as whole source file.
-	file, err = parser.ParseFile(fset, filename, src, parserMode)
-	// If there's no error, return.  If the error is that the source file didn't begin with a
-	// package line and source fragments are ok, fall through to
-	// try as a source fragment.  Stop and return on any other error.
-	if err == nil || !fragmentOk || !strings.Contains(err.Error(), "expected 'package'") {
-		return
-	}
-
-	// If this is a declaration list, make it a source file
-	// by inserting a package clause.
-	// Insert using a ;, not a newline, so that the line numbers
-	// in psrc match the ones in src.
-	psrc := append([]byte("package p;"), src...)
-	file, err = parser.ParseFile(fset, filename, psrc, parserMode)
-	if err == nil {
-		sourceAdj = func(src []byte, indent int) []byte {
-			// Remove the package clause.
-			// Gofmt has turned the ; into a \n.
-			src = src[indent+len("package p\n"):]
-			return bytes.TrimSpace(src)
-		}
-		return
-	}
-	// If the error is that the source file didn't begin with a
-	// declaration, fall through to try as a statement list.
-	// Stop and return on any other error.
-	if !strings.Contains(err.Error(), "expected declaration") {
-		return
-	}
-
-	// If this is a statement list, make it a source file
-	// by inserting a package clause and turning the list
-	// into a function body.  This handles expressions too.
-	// Insert using a ;, not a newline, so that the line numbers
-	// in fsrc match the ones in src.
-	fsrc := append(append([]byte("package p; func _() {"), src...), '\n', '}')
-	file, err = parser.ParseFile(fset, filename, fsrc, parserMode)
-	if err == nil {
-		sourceAdj = func(src []byte, indent int) []byte {
-			// Cap adjusted indent to zero.
-			if indent < 0 {
-				indent = 0
-			}
-			// Remove the wrapping.
-			// Gofmt has turned the ; into a \n\n.
-			// There will be two non-blank lines with indent, hence 2*indent.
-			src = src[2*indent+len("package p\n\nfunc _() {"):]
-			src = src[:len(src)-(indent+len("\n}\n"))]
-			return bytes.TrimSpace(src)
-		}
-		// Gofmt has also indented the function body one level.
-		// Adjust that with indentAdj.
-		indentAdj = -1
-	}
-
-	// Succeeded, or out of options.
-	return
-}
-
-// format formats the given package file originally obtained from src
-// and adjusts the result based on the original source via sourceAdj
-// and indentAdj.
-func format(
-	fset *token.FileSet,
-	file *ast.File,
-	sourceAdj func(src []byte, indent int) []byte,
-	indentAdj int,
-	src []byte,
-	cfg printer.Config,
-) ([]byte, error) {
-	if sourceAdj == nil {
-		// Complete source file.
-		var buf bytes.Buffer
-		err := cfg.Fprint(&buf, fset, file)
-		if err != nil {
-			return nil, err
-		}
-		return buf.Bytes(), nil
-	}
-
-	// Partial source file.
-	// Determine and prepend leading space.
-	i, j := 0, 0
-	for j < len(src) && isSpace(src[j]) {
-		if src[j] == '\n' {
-			i = j + 1 // byte offset of last line in leading space
-		}
-		j++
-	}
-	var res []byte
-	res = append(res, src[:i]...)
-
-	// Determine and prepend indentation of first code line.
-	// Spaces are ignored unless there are no tabs,
-	// in which case spaces count as one tab.
-	indent := 0
-	hasSpace := false
-	for _, b := range src[i:j] {
-		switch b {
-		case ' ':
-			hasSpace = true
-		case '\t':
-			indent++
-		}
-	}
-	if indent == 0 && hasSpace {
-		indent = 1
-	}
-	for i := 0; i < indent; i++ {
-		res = append(res, '\t')
-	}
-
-	// Format the source.
-	// Write it without any leading and trailing space.
-	cfg.Indent = indent + indentAdj
-	var buf bytes.Buffer
-	err := cfg.Fprint(&buf, fset, file)
-	if err != nil {
-		return nil, err
-	}
-	res = append(res, sourceAdj(buf.Bytes(), cfg.Indent)...)
-
-	// Determine and append trailing space.
-	i = len(src)
-	for i > 0 && isSpace(src[i-1]) {
-		i--
-	}
-	return append(res, src[i:]...), nil
-}
-
-func isSpace(b byte) bool {
-	return b == ' ' || b == '\t' || b == '\n' || b == '\r'
-}
diff --git a/libgo/go/go/format/format_test.go b/libgo/go/go/format/format_test.go
index d7846bec652..000c611aa25 100644
--- a/libgo/go/go/format/format_test.go
+++ b/libgo/go/go/format/format_test.go
@@ -91,7 +91,11 @@ var tests = []string{
 	"\n\t\t\n\n\t\t\tx := 0\n\t\t\tconst s = `\n\t\tfoo\n`\n\n\n", // no indentation removed inside raw strings
 
 	// comments
-	"i := 5 /* Comment */", // Issue 5551.
+	"i := 5 /* Comment */",         // Issue 5551.
+	"\ta()\n//line :1",             // Issue 11276.
+	"\t//xxx\n\ta()\n//line :2",    // Issue 11276.
+	"\ta() //line :1\n\tb()\n",     // Issue 11276.
+	"x := 0\n//line :1\n//line :2", // Issue 11276.
 
 	// erroneous programs
 	"ERROR1 + 2 +",
diff --git a/libgo/go/go/importer/importer.go b/libgo/go/go/importer/importer.go
new file mode 100644
index 00000000000..4590ca30e60
--- /dev/null
+++ b/libgo/go/go/importer/importer.go
@@ -0,0 +1,69 @@
+// Copyright 2015 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 importer provides access to export data importers.
+package importer
+
+import (
+	"go/internal/gccgoimporter"
+	"go/internal/gcimporter"
+	"go/types"
+	"io"
+	"runtime"
+)
+
+// A Lookup function returns a reader to access package data for
+// a given import path, or an error if no matching package is found.
+type Lookup func(path string) (io.ReadCloser, error)
+
+// For returns an Importer for the given compiler and lookup interface,
+// or nil. Supported compilers are "gc", and "gccgo". If lookup is nil,
+// the default package lookup mechanism for the given compiler is used.
+func For(compiler string, lookup Lookup) types.Importer {
+	switch compiler {
+	case "gc":
+		if lookup == nil {
+			return make(gcimports)
+		}
+		panic("gc importer for custom import path lookup not yet implemented")
+	case "gccgo":
+		if lookup == nil {
+			var inst gccgoimporter.GccgoInstallation
+			if err := inst.InitFromDriver("gccgo"); err != nil {
+				return nil
+			}
+			return &gccgoimports{
+				packages: make(map[string]*types.Package),
+				importer: inst.GetImporter(nil, nil),
+			}
+		}
+		panic("gccgo importer for custom import path lookup not yet implemented")
+	}
+	// compiler not supported
+	return nil
+}
+
+// Default returns an Importer for the compiler that built the running binary.
+func Default() types.Importer {
+	return For(runtime.Compiler, nil)
+}
+
+// gc support
+
+type gcimports map[string]*types.Package
+
+func (m gcimports) Import(path string) (*types.Package, error) {
+	return gcimporter.Import(m, path)
+}
+
+// gccgo support
+
+type gccgoimports struct {
+	packages map[string]*types.Package
+	importer gccgoimporter.Importer
+}
+
+func (m *gccgoimports) Import(path string) (*types.Package, error) {
+	return m.importer(m.packages, path)
+}
diff --git a/libgo/go/go/internal/gccgoimporter/gccgoinstallation.go b/libgo/go/go/internal/gccgoimporter/gccgoinstallation.go
new file mode 100644
index 00000000000..622dfc8b696
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/gccgoinstallation.go
@@ -0,0 +1,94 @@
+// Copyright 2013 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 gccgoimporter
+
+import (
+	"bufio"
+	"go/types"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+// Information about a specific installation of gccgo.
+type GccgoInstallation struct {
+	// Version of gcc (e.g. 4.8.0).
+	GccVersion string
+
+	// Target triple (e.g. x86_64-unknown-linux-gnu).
+	TargetTriple string
+
+	// Built-in library paths used by this installation.
+	LibPaths []string
+}
+
+// Ask the driver at the given path for information for this GccgoInstallation.
+func (inst *GccgoInstallation) InitFromDriver(gccgoPath string) (err error) {
+	cmd := exec.Command(gccgoPath, "-###", "-S", "-x", "go", "-")
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		return
+	}
+
+	err = cmd.Start()
+	if err != nil {
+		return
+	}
+
+	scanner := bufio.NewScanner(stderr)
+	for scanner.Scan() {
+		line := scanner.Text()
+		switch {
+		case strings.HasPrefix(line, "Target: "):
+			inst.TargetTriple = line[8:]
+
+		case line[0] == ' ':
+			args := strings.Fields(line)
+			for _, arg := range args[1:] {
+				if strings.HasPrefix(arg, "-L") {
+					inst.LibPaths = append(inst.LibPaths, arg[2:])
+				}
+			}
+		}
+	}
+
+	stdout, err := exec.Command(gccgoPath, "-dumpversion").Output()
+	if err != nil {
+		return
+	}
+	inst.GccVersion = strings.TrimSpace(string(stdout))
+
+	return
+}
+
+// Return the list of export search paths for this GccgoInstallation.
+func (inst *GccgoInstallation) SearchPaths() (paths []string) {
+	for _, lpath := range inst.LibPaths {
+		spath := filepath.Join(lpath, "go", inst.GccVersion)
+		fi, err := os.Stat(spath)
+		if err != nil || !fi.IsDir() {
+			continue
+		}
+		paths = append(paths, spath)
+
+		spath = filepath.Join(spath, inst.TargetTriple)
+		fi, err = os.Stat(spath)
+		if err != nil || !fi.IsDir() {
+			continue
+		}
+		paths = append(paths, spath)
+	}
+
+	paths = append(paths, inst.LibPaths...)
+
+	return
+}
+
+// Return an importer that searches incpaths followed by the gcc installation's
+// built-in search paths and the current directory.
+func (inst *GccgoInstallation) GetImporter(incpaths []string, initmap map[*types.Package]InitData) Importer {
+	return GetImporter(append(append(incpaths, inst.SearchPaths()...), "."), initmap)
+}
diff --git a/libgo/go/go/internal/gccgoimporter/gccgoinstallation_test.go b/libgo/go/go/internal/gccgoimporter/gccgoinstallation_test.go
new file mode 100644
index 00000000000..a2acaf7331a
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/gccgoinstallation_test.go
@@ -0,0 +1,197 @@
+// Copyright 2013 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 gccgoimporter
+
+import (
+	"go/types"
+	"runtime"
+	"testing"
+)
+
+var importablePackages = [...]string{
+	"archive/tar",
+	"archive/zip",
+	"bufio",
+	"bytes",
+	"compress/bzip2",
+	"compress/flate",
+	"compress/gzip",
+	"compress/lzw",
+	"compress/zlib",
+	"container/heap",
+	"container/list",
+	"container/ring",
+	"crypto/aes",
+	"crypto/cipher",
+	"crypto/des",
+	"crypto/dsa",
+	"crypto/ecdsa",
+	"crypto/elliptic",
+	"crypto",
+	"crypto/hmac",
+	"crypto/md5",
+	"crypto/rand",
+	"crypto/rc4",
+	"crypto/rsa",
+	"crypto/sha1",
+	"crypto/sha256",
+	"crypto/sha512",
+	"crypto/subtle",
+	"crypto/tls",
+	"crypto/x509",
+	"crypto/x509/pkix",
+	"database/sql/driver",
+	"database/sql",
+	"debug/dwarf",
+	"debug/elf",
+	"debug/gosym",
+	"debug/macho",
+	"debug/pe",
+	"encoding/ascii85",
+	"encoding/asn1",
+	"encoding/base32",
+	"encoding/base64",
+	"encoding/binary",
+	"encoding/csv",
+	"encoding/gob",
+	"encoding",
+	"encoding/hex",
+	"encoding/json",
+	"encoding/pem",
+	"encoding/xml",
+	"errors",
+	"exp/proxy",
+	"exp/terminal",
+	"expvar",
+	"flag",
+	"fmt",
+	"go/ast",
+	"go/build",
+	"go/doc",
+	"go/format",
+	"go/parser",
+	"go/printer",
+	"go/scanner",
+	"go/token",
+	"hash/adler32",
+	"hash/crc32",
+	"hash/crc64",
+	"hash/fnv",
+	"hash",
+	"html",
+	"html/template",
+	"image/color",
+	"image/color/palette",
+	"image/draw",
+	"image/gif",
+	"image",
+	"image/jpeg",
+	"image/png",
+	"index/suffixarray",
+	"io",
+	"io/ioutil",
+	"log",
+	"log/syslog",
+	"math/big",
+	"math/cmplx",
+	"math",
+	"math/rand",
+	"mime",
+	"mime/multipart",
+	"net",
+	"net/http/cgi",
+	"net/http/cookiejar",
+	"net/http/fcgi",
+	"net/http",
+	"net/http/httptest",
+	"net/http/httputil",
+	"net/http/pprof",
+	"net/mail",
+	"net/rpc",
+	"net/rpc/jsonrpc",
+	"net/smtp",
+	"net/textproto",
+	"net/url",
+	"old/regexp",
+	"old/template",
+	"os/exec",
+	"os",
+	"os/signal",
+	"os/user",
+	"path/filepath",
+	"path",
+	"reflect",
+	"regexp",
+	"regexp/syntax",
+	"runtime/debug",
+	"runtime",
+	"runtime/pprof",
+	"sort",
+	"strconv",
+	"strings",
+	"sync/atomic",
+	"sync",
+	"syscall",
+	"testing",
+	"testing/iotest",
+	"testing/quick",
+	"text/scanner",
+	"text/tabwriter",
+	"text/template",
+	"text/template/parse",
+	"time",
+	"unicode",
+	"unicode/utf16",
+	"unicode/utf8",
+}
+
+func TestInstallationImporter(t *testing.T) {
+	// This test relies on gccgo being around, which it most likely will be if we
+	// were compiled with gccgo.
+	if runtime.Compiler != "gccgo" {
+		t.Skip("This test needs gccgo")
+		return
+	}
+
+	// Even when we have gccgo, this doesn't work while building
+	// gccgo itself.
+	t.Skip("gccgo is not necessarily available")
+
+	var inst GccgoInstallation
+	err := inst.InitFromDriver("gccgo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	imp := inst.GetImporter(nil, nil)
+
+	// Ensure we don't regress the number of packages we can parse. First import
+	// all packages into the same map and then each individually.
+	pkgMap := make(map[string]*types.Package)
+	for _, pkg := range importablePackages {
+		_, err = imp(pkgMap, pkg)
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	for _, pkg := range importablePackages {
+		_, err = imp(make(map[string]*types.Package), pkg)
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	// Test for certain specific entities in the imported data.
+	for _, test := range [...]importerTest{
+		{pkgpath: "io", name: "Reader", want: "type Reader interface{Read(p []uint8) (n int, err error)}"},
+		{pkgpath: "io", name: "ReadWriter", want: "type ReadWriter interface{Reader; Writer}"},
+		{pkgpath: "math", name: "Pi", want: "const Pi untyped float"},
+		{pkgpath: "math", name: "Sin", want: "func Sin(x float64) float64"},
+		{pkgpath: "sort", name: "Ints", want: "func Ints(a []int)"},
+		{pkgpath: "unsafe", name: "Pointer", want: "type Pointer unsafe.Pointer"},
+	} {
+		runImporterTest(t, imp, nil, &test)
+	}
+}
diff --git a/libgo/go/go/internal/gccgoimporter/importer.go b/libgo/go/go/internal/gccgoimporter/importer.go
new file mode 100644
index 00000000000..aa0d01afdf3
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/importer.go
@@ -0,0 +1,212 @@
+// Copyright 2013 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 gccgoimporter implements Import for gccgo-generated object files.
+package gccgoimporter // import "go/internal/gccgoimporter"
+
+import (
+	"bytes"
+	"debug/elf"
+	"fmt"
+	"go/types"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+// A PackageInit describes an imported package that needs initialization.
+type PackageInit struct {
+	Name     string // short package name
+	InitFunc string // name of init function
+	Priority int    // priority of init function, see InitData.Priority
+}
+
+// The gccgo-specific init data for a package.
+type InitData struct {
+	// Initialization priority of this package relative to other packages.
+	// This is based on the maximum depth of the package's dependency graph;
+	// it is guaranteed to be greater than that of its dependencies.
+	Priority int
+
+	// The list of packages which this package depends on to be initialized,
+	// including itself if needed. This is the subset of the transitive closure of
+	// the package's dependencies that need initialization.
+	Inits []PackageInit
+}
+
+// Locate the file from which to read export data.
+// This is intended to replicate the logic in gofrontend.
+func findExportFile(searchpaths []string, pkgpath string) (string, error) {
+	for _, spath := range searchpaths {
+		pkgfullpath := filepath.Join(spath, pkgpath)
+		pkgdir, name := filepath.Split(pkgfullpath)
+
+		for _, filepath := range [...]string{
+			pkgfullpath,
+			pkgfullpath + ".gox",
+			pkgdir + "lib" + name + ".so",
+			pkgdir + "lib" + name + ".a",
+			pkgfullpath + ".o",
+		} {
+			fi, err := os.Stat(filepath)
+			if err == nil && !fi.IsDir() {
+				return filepath, nil
+			}
+		}
+	}
+
+	return "", fmt.Errorf("%s: could not find export data (tried %s)", pkgpath, strings.Join(searchpaths, ":"))
+}
+
+const (
+	gccgov1Magic    = "v1;\n"
+	goimporterMagic = "\n$$ "
+	archiveMagic    = "!<ar"
+)
+
+// Opens the export data file at the given path. If this is an ELF file,
+// searches for and opens the .go_export section. If this is an archive,
+// reads the export data from the first member, which is assumed to be an ELF file.
+// This is intended to replicate the logic in gofrontend.
+func openExportFile(fpath string) (reader io.ReadSeeker, closer io.Closer, err error) {
+	f, err := os.Open(fpath)
+	if err != nil {
+		return
+	}
+	closer = f
+	defer func() {
+		if err != nil && closer != nil {
+			f.Close()
+		}
+	}()
+
+	var magic [4]byte
+	_, err = f.ReadAt(magic[:], 0)
+	if err != nil {
+		return
+	}
+	// reset to offset 0 - needed on Plan 9 (see issue #11265)
+	// TODO: remove once issue #11265 has been resolved.
+	_, err = f.Seek(0, 0)
+	if err != nil {
+		return
+	}
+
+	var elfreader io.ReaderAt
+	switch string(magic[:]) {
+	case gccgov1Magic, goimporterMagic:
+		// Raw export data.
+		reader = f
+		return
+
+	case archiveMagic:
+		// TODO(pcc): Read the archive directly instead of using "ar".
+		f.Close()
+		closer = nil
+
+		cmd := exec.Command("ar", "p", fpath)
+		var out []byte
+		out, err = cmd.Output()
+		if err != nil {
+			return
+		}
+
+		elfreader = bytes.NewReader(out)
+
+	default:
+		elfreader = f
+	}
+
+	ef, err := elf.NewFile(elfreader)
+	if err != nil {
+		return
+	}
+
+	sec := ef.Section(".go_export")
+	if sec == nil {
+		err = fmt.Errorf("%s: .go_export section not found", fpath)
+		return
+	}
+
+	reader = sec.Open()
+	return
+}
+
+// An Importer resolves import paths to Packages. The imports map records
+// packages already known, indexed by package path.
+// An importer must determine the canonical package path and check imports
+// to see if it is already present in the map. If so, the Importer can return
+// the map entry. Otherwise, the importer must load the package data for the
+// given path into a new *Package, record it in imports map, and return the
+// package.
+type Importer func(imports map[string]*types.Package, path string) (*types.Package, error)
+
+func GetImporter(searchpaths []string, initmap map[*types.Package]InitData) Importer {
+	return func(imports map[string]*types.Package, pkgpath string) (pkg *types.Package, err error) {
+		if pkgpath == "unsafe" {
+			return types.Unsafe, nil
+		}
+
+		fpath, err := findExportFile(searchpaths, pkgpath)
+		if err != nil {
+			return
+		}
+
+		reader, closer, err := openExportFile(fpath)
+		if err != nil {
+			return
+		}
+		if closer != nil {
+			defer closer.Close()
+		}
+
+		var magic [4]byte
+		_, err = reader.Read(magic[:])
+		if err != nil {
+			return
+		}
+		_, err = reader.Seek(0, 0)
+		if err != nil {
+			return
+		}
+
+		switch string(magic[:]) {
+		case gccgov1Magic:
+			var p parser
+			p.init(fpath, reader, imports)
+			pkg = p.parsePackage()
+			if initmap != nil {
+				initmap[pkg] = p.initdata
+			}
+
+		// Excluded for now: Standard gccgo doesn't support this import format currently.
+		// case goimporterMagic:
+		// 	var data []byte
+		// 	data, err = ioutil.ReadAll(reader)
+		// 	if err != nil {
+		// 		return
+		// 	}
+		// 	var n int
+		// 	n, pkg, err = importer.ImportData(imports, data)
+		// 	if err != nil {
+		// 		return
+		// 	}
+
+		// 	if initmap != nil {
+		// 		suffixreader := bytes.NewReader(data[n:])
+		// 		var p parser
+		// 		p.init(fpath, suffixreader, nil)
+		// 		p.parseInitData()
+		// 		initmap[pkg] = p.initdata
+		// 	}
+
+		default:
+			err = fmt.Errorf("unrecognized magic string: %q", string(magic[:]))
+		}
+
+		return
+	}
+}
diff --git a/libgo/go/go/internal/gccgoimporter/importer_test.go b/libgo/go/go/internal/gccgoimporter/importer_test.go
new file mode 100644
index 00000000000..f3bcadbaf77
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/importer_test.go
@@ -0,0 +1,171 @@
+// Copyright 2013 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 gccgoimporter
+
+import (
+	"go/types"
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+type importerTest struct {
+	pkgpath, name, want, wantval string
+	wantinits                    []string
+}
+
+func runImporterTest(t *testing.T, imp Importer, initmap map[*types.Package]InitData, test *importerTest) {
+	pkg, err := imp(make(map[string]*types.Package), test.pkgpath)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	if test.name != "" {
+		obj := pkg.Scope().Lookup(test.name)
+		if obj == nil {
+			t.Errorf("%s: object not found", test.name)
+			return
+		}
+
+		got := types.ObjectString(obj, types.RelativeTo(pkg))
+		if got != test.want {
+			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
+		}
+
+		if test.wantval != "" {
+			gotval := obj.(*types.Const).Val().String()
+			if gotval != test.wantval {
+				t.Errorf("%s: got val %q; want val %q", test.name, gotval, test.wantval)
+			}
+		}
+	}
+
+	if len(test.wantinits) > 0 {
+		initdata := initmap[pkg]
+		found := false
+		// Check that the package's own init function has the package's priority
+		for _, pkginit := range initdata.Inits {
+			if pkginit.InitFunc == test.wantinits[0] {
+				if initdata.Priority != pkginit.Priority {
+					t.Errorf("%s: got self priority %d; want %d", test.pkgpath, pkginit.Priority, initdata.Priority)
+				}
+				found = true
+				break
+			}
+		}
+
+		if !found {
+			t.Errorf("%s: could not find expected function %q", test.pkgpath, test.wantinits[0])
+		}
+
+		// Each init function in the list other than the first one is a
+		// dependency of the function immediately before it. Check that
+		// the init functions appear in descending priority order.
+		priority := initdata.Priority
+		for _, wantdepinit := range test.wantinits[1:] {
+			found = false
+			for _, pkginit := range initdata.Inits {
+				if pkginit.InitFunc == wantdepinit {
+					if priority <= pkginit.Priority {
+						t.Errorf("%s: got dep priority %d; want less than %d", test.pkgpath, pkginit.Priority, priority)
+					}
+					found = true
+					priority = pkginit.Priority
+					break
+				}
+			}
+
+			if !found {
+				t.Errorf("%s: could not find expected function %q", test.pkgpath, wantdepinit)
+			}
+		}
+	}
+}
+
+var importerTests = [...]importerTest{
+	{pkgpath: "pointer", name: "Int8Ptr", want: "type Int8Ptr *int8"},
+	{pkgpath: "complexnums", name: "NN", want: "const NN untyped complex", wantval: "(-1/1 + -1/1i)"},
+	{pkgpath: "complexnums", name: "NP", want: "const NP untyped complex", wantval: "(-1/1 + 1/1i)"},
+	{pkgpath: "complexnums", name: "PN", want: "const PN untyped complex", wantval: "(1/1 + -1/1i)"},
+	{pkgpath: "complexnums", name: "PP", want: "const PP untyped complex", wantval: "(1/1 + 1/1i)"},
+	// TODO: enable this entry once bug has been tracked down
+	//{pkgpath: "imports", wantinits: []string{"imports..import", "fmt..import", "math..import"}},
+}
+
+func TestGoxImporter(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	initmap := make(map[*types.Package]InitData)
+	imp := GetImporter([]string{"testdata"}, initmap)
+
+	for _, test := range importerTests {
+		runImporterTest(t, imp, initmap, &test)
+	}
+}
+
+func TestObjImporter(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	// This test relies on gccgo being around, which it most likely will be if we
+	// were compiled with gccgo.
+	if runtime.Compiler != "gccgo" {
+		t.Skip("This test needs gccgo")
+		return
+	}
+
+	tmpdir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	initmap := make(map[*types.Package]InitData)
+	imp := GetImporter([]string{tmpdir}, initmap)
+
+	artmpdir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	arinitmap := make(map[*types.Package]InitData)
+	arimp := GetImporter([]string{artmpdir}, arinitmap)
+
+	for _, test := range importerTests {
+		gofile := filepath.Join("testdata", test.pkgpath+".go")
+		ofile := filepath.Join(tmpdir, test.pkgpath+".o")
+		afile := filepath.Join(artmpdir, "lib"+test.pkgpath+".a")
+
+		cmd := exec.Command("gccgo", "-fgo-pkgpath="+test.pkgpath, "-c", "-o", ofile, gofile)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			t.Logf("%s", out)
+			t.Fatalf("gccgo %s failed: %s", gofile, err)
+		}
+
+		runImporterTest(t, imp, initmap, &test)
+
+		cmd = exec.Command("ar", "cr", afile, ofile)
+		out, err = cmd.CombinedOutput()
+		if err != nil {
+			t.Logf("%s", out)
+			t.Fatalf("ar cr %s %s failed: %s", afile, ofile, err)
+		}
+
+		runImporterTest(t, arimp, arinitmap, &test)
+
+		if err = os.Remove(ofile); err != nil {
+			t.Fatal(err)
+		}
+		if err = os.Remove(afile); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if err = os.Remove(tmpdir); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/libgo/go/go/internal/gccgoimporter/parser.go b/libgo/go/go/internal/gccgoimporter/parser.go
new file mode 100644
index 00000000000..c06cce435b1
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/parser.go
@@ -0,0 +1,855 @@
+// Copyright 2013 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 gccgoimporter
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"strconv"
+	"strings"
+	"text/scanner"
+)
+
+type parser struct {
+	scanner  scanner.Scanner
+	tok      rune                      // current token
+	lit      string                    // literal string; only valid for Ident, Int, String tokens
+	pkgpath  string                    // package path of imported package
+	pkgname  string                    // name of imported package
+	pkg      *types.Package            // reference to imported package
+	imports  map[string]*types.Package // package path -> package object
+	typeMap  map[int]types.Type        // type number -> type
+	initdata InitData                  // package init priority data
+}
+
+func (p *parser) init(filename string, src io.Reader, imports map[string]*types.Package) {
+	p.scanner.Init(src)
+	p.scanner.Error = func(_ *scanner.Scanner, msg string) { p.error(msg) }
+	p.scanner.Mode = scanner.ScanIdents | scanner.ScanInts | scanner.ScanFloats | scanner.ScanStrings | scanner.ScanComments | scanner.SkipComments
+	p.scanner.Whitespace = 1<<'\t' | 1<<'\n' | 1<<' '
+	p.scanner.Filename = filename // for good error messages
+	p.next()
+	p.imports = imports
+	p.typeMap = make(map[int]types.Type)
+}
+
+type importError struct {
+	pos scanner.Position
+	err error
+}
+
+func (e importError) Error() string {
+	return fmt.Sprintf("import error %s (byte offset = %d): %s", e.pos, e.pos.Offset, e.err)
+}
+
+func (p *parser) error(err interface{}) {
+	if s, ok := err.(string); ok {
+		err = errors.New(s)
+	}
+	// panic with a runtime.Error if err is not an error
+	panic(importError{p.scanner.Pos(), err.(error)})
+}
+
+func (p *parser) errorf(format string, args ...interface{}) {
+	p.error(fmt.Errorf(format, args...))
+}
+
+func (p *parser) expect(tok rune) string {
+	lit := p.lit
+	if p.tok != tok {
+		p.errorf("expected %s, got %s (%s)", scanner.TokenString(tok), scanner.TokenString(p.tok), lit)
+	}
+	p.next()
+	return lit
+}
+
+func (p *parser) expectKeyword(keyword string) {
+	lit := p.expect(scanner.Ident)
+	if lit != keyword {
+		p.errorf("expected keyword %s, got %q", keyword, lit)
+	}
+}
+
+func (p *parser) parseString() string {
+	str, err := strconv.Unquote(p.expect(scanner.String))
+	if err != nil {
+		p.error(err)
+	}
+	return str
+}
+
+// unquotedString     = { unquotedStringChar } .
+// unquotedStringChar = <neither a whitespace nor a ';' char> .
+func (p *parser) parseUnquotedString() string {
+	if p.tok == scanner.EOF {
+		p.error("unexpected EOF")
+	}
+	var buf bytes.Buffer
+	buf.WriteString(p.scanner.TokenText())
+	// This loop needs to examine each character before deciding whether to consume it. If we see a semicolon,
+	// we need to let it be consumed by p.next().
+	for ch := p.scanner.Peek(); ch != ';' && ch != scanner.EOF && p.scanner.Whitespace&(1<<uint(ch)) == 0; ch = p.scanner.Peek() {
+		buf.WriteRune(ch)
+		p.scanner.Next()
+	}
+	p.next()
+	return buf.String()
+}
+
+func (p *parser) next() {
+	p.tok = p.scanner.Scan()
+	switch p.tok {
+	case scanner.Ident, scanner.Int, scanner.Float, scanner.String, '·':
+		p.lit = p.scanner.TokenText()
+	default:
+		p.lit = ""
+	}
+}
+
+func (p *parser) parseQualifiedName() (path, name string) {
+	return p.parseQualifiedNameStr(p.parseString())
+}
+
+func (p *parser) parseUnquotedQualifiedName() (path, name string) {
+	return p.parseQualifiedNameStr(p.parseUnquotedString())
+}
+
+// qualifiedName = [ ["."] unquotedString "." ] unquotedString .
+//
+// The above production uses greedy matching.
+func (p *parser) parseQualifiedNameStr(unquotedName string) (pkgpath, name string) {
+	parts := strings.Split(unquotedName, ".")
+	if parts[0] == "" {
+		parts = parts[1:]
+	}
+
+	switch len(parts) {
+	case 0:
+		p.errorf("malformed qualified name: %q", unquotedName)
+	case 1:
+		// unqualified name
+		pkgpath = p.pkgpath
+		name = parts[0]
+	default:
+		// qualified name, which may contain periods
+		pkgpath = strings.Join(parts[0:len(parts)-1], ".")
+		name = parts[len(parts)-1]
+	}
+
+	return
+}
+
+// getPkg returns the package for a given path. If the package is
+// not found but we have a package name, create the package and
+// add it to the p.imports map.
+//
+func (p *parser) getPkg(pkgpath, name string) *types.Package {
+	// package unsafe is not in the imports map - handle explicitly
+	if pkgpath == "unsafe" {
+		return types.Unsafe
+	}
+	pkg := p.imports[pkgpath]
+	if pkg == nil && name != "" {
+		pkg = types.NewPackage(pkgpath, name)
+		p.imports[pkgpath] = pkg
+	}
+	return pkg
+}
+
+// parseExportedName is like parseQualifiedName, but
+// the package path is resolved to an imported *types.Package.
+//
+// ExportedName = string [string] .
+func (p *parser) parseExportedName() (pkg *types.Package, name string) {
+	path, name := p.parseQualifiedName()
+	var pkgname string
+	if p.tok == scanner.String {
+		pkgname = p.parseString()
+	}
+	pkg = p.getPkg(path, pkgname)
+	if pkg == nil {
+		p.errorf("package %s (path = %q) not found", name, path)
+	}
+	return
+}
+
+// Name = QualifiedName | "?" .
+func (p *parser) parseName() string {
+	if p.tok == '?' {
+		// Anonymous.
+		p.next()
+		return ""
+	}
+	// The package path is redundant for us. Don't try to parse it.
+	_, name := p.parseUnquotedQualifiedName()
+	return name
+}
+
+func deref(typ types.Type) types.Type {
+	if p, _ := typ.(*types.Pointer); p != nil {
+		typ = p.Elem()
+	}
+	return typ
+}
+
+// Field = Name Type [string] .
+func (p *parser) parseField(pkg *types.Package) (field *types.Var, tag string) {
+	name := p.parseName()
+	typ := p.parseType(pkg)
+	anon := false
+	if name == "" {
+		anon = true
+		switch typ := deref(typ).(type) {
+		case *types.Basic:
+			name = typ.Name()
+		case *types.Named:
+			name = typ.Obj().Name()
+		default:
+			p.error("anonymous field expected")
+		}
+	}
+	field = types.NewField(token.NoPos, pkg, name, typ, anon)
+	if p.tok == scanner.String {
+		tag = p.parseString()
+	}
+	return
+}
+
+// Param = Name ["..."] Type .
+func (p *parser) parseParam(pkg *types.Package) (param *types.Var, isVariadic bool) {
+	name := p.parseName()
+	if p.tok == '.' {
+		p.next()
+		p.expect('.')
+		p.expect('.')
+		isVariadic = true
+	}
+	typ := p.parseType(pkg)
+	if isVariadic {
+		typ = types.NewSlice(typ)
+	}
+	param = types.NewParam(token.NoPos, pkg, name, typ)
+	return
+}
+
+// Var = Name Type .
+func (p *parser) parseVar(pkg *types.Package) *types.Var {
+	name := p.parseName()
+	return types.NewVar(token.NoPos, pkg, name, p.parseType(pkg))
+}
+
+// ConstValue     = string | "false" | "true" | ["-"] (int ["'"] | FloatOrComplex) .
+// FloatOrComplex = float ["i" | ("+"|"-") float "i"] .
+func (p *parser) parseConstValue() (val constant.Value, typ types.Type) {
+	switch p.tok {
+	case scanner.String:
+		str := p.parseString()
+		val = constant.MakeString(str)
+		typ = types.Typ[types.UntypedString]
+		return
+
+	case scanner.Ident:
+		b := false
+		switch p.lit {
+		case "false":
+		case "true":
+			b = true
+
+		default:
+			p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
+		}
+
+		p.next()
+		val = constant.MakeBool(b)
+		typ = types.Typ[types.UntypedBool]
+		return
+	}
+
+	sign := ""
+	if p.tok == '-' {
+		p.next()
+		sign = "-"
+	}
+
+	switch p.tok {
+	case scanner.Int:
+		val = constant.MakeFromLiteral(sign+p.lit, token.INT, 0)
+		if val == nil {
+			p.error("could not parse integer literal")
+		}
+
+		p.next()
+		if p.tok == '\'' {
+			p.next()
+			typ = types.Typ[types.UntypedRune]
+		} else {
+			typ = types.Typ[types.UntypedInt]
+		}
+
+	case scanner.Float:
+		re := sign + p.lit
+		p.next()
+
+		var im string
+		switch p.tok {
+		case '+':
+			p.next()
+			im = p.expect(scanner.Float)
+
+		case '-':
+			p.next()
+			im = "-" + p.expect(scanner.Float)
+
+		case scanner.Ident:
+			// re is in fact the imaginary component. Expect "i" below.
+			im = re
+			re = "0"
+
+		default:
+			val = constant.MakeFromLiteral(re, token.FLOAT, 0)
+			if val == nil {
+				p.error("could not parse float literal")
+			}
+			typ = types.Typ[types.UntypedFloat]
+			return
+		}
+
+		p.expectKeyword("i")
+		reval := constant.MakeFromLiteral(re, token.FLOAT, 0)
+		if reval == nil {
+			p.error("could not parse real component of complex literal")
+		}
+		imval := constant.MakeFromLiteral(im+"i", token.IMAG, 0)
+		if imval == nil {
+			p.error("could not parse imag component of complex literal")
+		}
+		val = constant.BinaryOp(reval, token.ADD, imval)
+		typ = types.Typ[types.UntypedComplex]
+
+	default:
+		p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
+	}
+
+	return
+}
+
+// Const = Name [Type] "=" ConstValue .
+func (p *parser) parseConst(pkg *types.Package) *types.Const {
+	name := p.parseName()
+	var typ types.Type
+	if p.tok == '<' {
+		typ = p.parseType(pkg)
+	}
+	p.expect('=')
+	val, vtyp := p.parseConstValue()
+	if typ == nil {
+		typ = vtyp
+	}
+	return types.NewConst(token.NoPos, pkg, name, typ, val)
+}
+
+// TypeName = ExportedName .
+func (p *parser) parseTypeName() *types.TypeName {
+	pkg, name := p.parseExportedName()
+	scope := pkg.Scope()
+	if obj := scope.Lookup(name); obj != nil {
+		return obj.(*types.TypeName)
+	}
+	obj := types.NewTypeName(token.NoPos, pkg, name, nil)
+	// a named type may be referred to before the underlying type
+	// is known - set it up
+	types.NewNamed(obj, nil, nil)
+	scope.Insert(obj)
+	return obj
+}
+
+// NamedType = TypeName Type { Method } .
+// Method    = "func" "(" Param ")" Name ParamList ResultList ";" .
+func (p *parser) parseNamedType(n int) types.Type {
+	obj := p.parseTypeName()
+
+	pkg := obj.Pkg()
+	typ := obj.Type()
+	p.typeMap[n] = typ
+
+	nt, ok := typ.(*types.Named)
+	if !ok {
+		// This can happen for unsafe.Pointer, which is a TypeName holding a Basic type.
+		pt := p.parseType(pkg)
+		if pt != typ {
+			p.error("unexpected underlying type for non-named TypeName")
+		}
+		return typ
+	}
+
+	underlying := p.parseType(pkg)
+	if nt.Underlying() == nil {
+		nt.SetUnderlying(underlying.Underlying())
+	}
+
+	for p.tok == scanner.Ident {
+		// collect associated methods
+		p.expectKeyword("func")
+		p.expect('(')
+		receiver, _ := p.parseParam(pkg)
+		p.expect(')')
+		name := p.parseName()
+		params, isVariadic := p.parseParamList(pkg)
+		results := p.parseResultList(pkg)
+		p.expect(';')
+
+		sig := types.NewSignature(receiver, params, results, isVariadic)
+		nt.AddMethod(types.NewFunc(token.NoPos, pkg, name, sig))
+	}
+
+	return nt
+}
+
+func (p *parser) parseInt() int64 {
+	lit := p.expect(scanner.Int)
+	n, err := strconv.ParseInt(lit, 10, 0)
+	if err != nil {
+		p.error(err)
+	}
+	return n
+}
+
+// ArrayOrSliceType = "[" [ int ] "]" Type .
+func (p *parser) parseArrayOrSliceType(pkg *types.Package) types.Type {
+	p.expect('[')
+	if p.tok == ']' {
+		p.next()
+		return types.NewSlice(p.parseType(pkg))
+	}
+
+	n := p.parseInt()
+	p.expect(']')
+	return types.NewArray(p.parseType(pkg), n)
+}
+
+// MapType = "map" "[" Type "]" Type .
+func (p *parser) parseMapType(pkg *types.Package) types.Type {
+	p.expectKeyword("map")
+	p.expect('[')
+	key := p.parseType(pkg)
+	p.expect(']')
+	elem := p.parseType(pkg)
+	return types.NewMap(key, elem)
+}
+
+// ChanType = "chan" ["<-" | "-<"] Type .
+func (p *parser) parseChanType(pkg *types.Package) types.Type {
+	p.expectKeyword("chan")
+	dir := types.SendRecv
+	switch p.tok {
+	case '-':
+		p.next()
+		p.expect('<')
+		dir = types.SendOnly
+
+	case '<':
+		// don't consume '<' if it belongs to Type
+		if p.scanner.Peek() == '-' {
+			p.next()
+			p.expect('-')
+			dir = types.RecvOnly
+		}
+	}
+
+	return types.NewChan(dir, p.parseType(pkg))
+}
+
+// StructType = "struct" "{" { Field } "}" .
+func (p *parser) parseStructType(pkg *types.Package) types.Type {
+	p.expectKeyword("struct")
+
+	var fields []*types.Var
+	var tags []string
+
+	p.expect('{')
+	for p.tok != '}' && p.tok != scanner.EOF {
+		field, tag := p.parseField(pkg)
+		p.expect(';')
+		fields = append(fields, field)
+		tags = append(tags, tag)
+	}
+	p.expect('}')
+
+	return types.NewStruct(fields, tags)
+}
+
+// ParamList = "(" [ { Parameter "," } Parameter ] ")" .
+func (p *parser) parseParamList(pkg *types.Package) (*types.Tuple, bool) {
+	var list []*types.Var
+	isVariadic := false
+
+	p.expect('(')
+	for p.tok != ')' && p.tok != scanner.EOF {
+		if len(list) > 0 {
+			p.expect(',')
+		}
+		par, variadic := p.parseParam(pkg)
+		list = append(list, par)
+		if variadic {
+			if isVariadic {
+				p.error("... not on final argument")
+			}
+			isVariadic = true
+		}
+	}
+	p.expect(')')
+
+	return types.NewTuple(list...), isVariadic
+}
+
+// ResultList = Type | ParamList .
+func (p *parser) parseResultList(pkg *types.Package) *types.Tuple {
+	switch p.tok {
+	case '<':
+		return types.NewTuple(types.NewParam(token.NoPos, pkg, "", p.parseType(pkg)))
+
+	case '(':
+		params, _ := p.parseParamList(pkg)
+		return params
+
+	default:
+		return nil
+	}
+}
+
+// FunctionType = ParamList ResultList .
+func (p *parser) parseFunctionType(pkg *types.Package) *types.Signature {
+	params, isVariadic := p.parseParamList(pkg)
+	results := p.parseResultList(pkg)
+	return types.NewSignature(nil, params, results, isVariadic)
+}
+
+// Func = Name FunctionType .
+func (p *parser) parseFunc(pkg *types.Package) *types.Func {
+	name := p.parseName()
+	if strings.ContainsRune(name, '$') {
+		// This is a Type$equal or Type$hash function, which we don't want to parse,
+		// except for the types.
+		p.discardDirectiveWhileParsingTypes(pkg)
+		return nil
+	}
+	return types.NewFunc(token.NoPos, pkg, name, p.parseFunctionType(pkg))
+}
+
+// InterfaceType = "interface" "{" { ("?" Type | Func) ";" } "}" .
+func (p *parser) parseInterfaceType(pkg *types.Package) types.Type {
+	p.expectKeyword("interface")
+
+	var methods []*types.Func
+	var typs []*types.Named
+
+	p.expect('{')
+	for p.tok != '}' && p.tok != scanner.EOF {
+		if p.tok == '?' {
+			p.next()
+			typs = append(typs, p.parseType(pkg).(*types.Named))
+		} else {
+			method := p.parseFunc(pkg)
+			methods = append(methods, method)
+		}
+		p.expect(';')
+	}
+	p.expect('}')
+
+	return types.NewInterface(methods, typs)
+}
+
+// PointerType = "*" ("any" | Type) .
+func (p *parser) parsePointerType(pkg *types.Package) types.Type {
+	p.expect('*')
+	if p.tok == scanner.Ident {
+		p.expectKeyword("any")
+		return types.Typ[types.UnsafePointer]
+	}
+	return types.NewPointer(p.parseType(pkg))
+}
+
+// TypeDefinition = NamedType | MapType | ChanType | StructType | InterfaceType | PointerType | ArrayOrSliceType | FunctionType .
+func (p *parser) parseTypeDefinition(pkg *types.Package, n int) types.Type {
+	var t types.Type
+	switch p.tok {
+	case scanner.String:
+		t = p.parseNamedType(n)
+
+	case scanner.Ident:
+		switch p.lit {
+		case "map":
+			t = p.parseMapType(pkg)
+
+		case "chan":
+			t = p.parseChanType(pkg)
+
+		case "struct":
+			t = p.parseStructType(pkg)
+
+		case "interface":
+			t = p.parseInterfaceType(pkg)
+		}
+
+	case '*':
+		t = p.parsePointerType(pkg)
+
+	case '[':
+		t = p.parseArrayOrSliceType(pkg)
+
+	case '(':
+		t = p.parseFunctionType(pkg)
+	}
+
+	p.typeMap[n] = t
+	return t
+}
+
+const (
+	// From gofrontend/go/export.h
+	// Note that these values are negative in the gofrontend and have been made positive
+	// in the gccgoimporter.
+	gccgoBuiltinINT8       = 1
+	gccgoBuiltinINT16      = 2
+	gccgoBuiltinINT32      = 3
+	gccgoBuiltinINT64      = 4
+	gccgoBuiltinUINT8      = 5
+	gccgoBuiltinUINT16     = 6
+	gccgoBuiltinUINT32     = 7
+	gccgoBuiltinUINT64     = 8
+	gccgoBuiltinFLOAT32    = 9
+	gccgoBuiltinFLOAT64    = 10
+	gccgoBuiltinINT        = 11
+	gccgoBuiltinUINT       = 12
+	gccgoBuiltinUINTPTR    = 13
+	gccgoBuiltinBOOL       = 15
+	gccgoBuiltinSTRING     = 16
+	gccgoBuiltinCOMPLEX64  = 17
+	gccgoBuiltinCOMPLEX128 = 18
+	gccgoBuiltinERROR      = 19
+	gccgoBuiltinBYTE       = 20
+	gccgoBuiltinRUNE       = 21
+)
+
+func lookupBuiltinType(typ int) types.Type {
+	return [...]types.Type{
+		gccgoBuiltinINT8:       types.Typ[types.Int8],
+		gccgoBuiltinINT16:      types.Typ[types.Int16],
+		gccgoBuiltinINT32:      types.Typ[types.Int32],
+		gccgoBuiltinINT64:      types.Typ[types.Int64],
+		gccgoBuiltinUINT8:      types.Typ[types.Uint8],
+		gccgoBuiltinUINT16:     types.Typ[types.Uint16],
+		gccgoBuiltinUINT32:     types.Typ[types.Uint32],
+		gccgoBuiltinUINT64:     types.Typ[types.Uint64],
+		gccgoBuiltinFLOAT32:    types.Typ[types.Float32],
+		gccgoBuiltinFLOAT64:    types.Typ[types.Float64],
+		gccgoBuiltinINT:        types.Typ[types.Int],
+		gccgoBuiltinUINT:       types.Typ[types.Uint],
+		gccgoBuiltinUINTPTR:    types.Typ[types.Uintptr],
+		gccgoBuiltinBOOL:       types.Typ[types.Bool],
+		gccgoBuiltinSTRING:     types.Typ[types.String],
+		gccgoBuiltinCOMPLEX64:  types.Typ[types.Complex64],
+		gccgoBuiltinCOMPLEX128: types.Typ[types.Complex128],
+		gccgoBuiltinERROR:      types.Universe.Lookup("error").Type(),
+		gccgoBuiltinBYTE:       types.Universe.Lookup("byte").Type(),
+		gccgoBuiltinRUNE:       types.Universe.Lookup("rune").Type(),
+	}[typ]
+}
+
+// Type = "<" "type" ( "-" int | int [ TypeDefinition ] ) ">" .
+func (p *parser) parseType(pkg *types.Package) (t types.Type) {
+	p.expect('<')
+	p.expectKeyword("type")
+
+	switch p.tok {
+	case scanner.Int:
+		n := p.parseInt()
+
+		if p.tok == '>' {
+			t = p.typeMap[int(n)]
+		} else {
+			t = p.parseTypeDefinition(pkg, int(n))
+		}
+
+	case '-':
+		p.next()
+		n := p.parseInt()
+		t = lookupBuiltinType(int(n))
+
+	default:
+		p.errorf("expected type number, got %s (%q)", scanner.TokenString(p.tok), p.lit)
+		return nil
+	}
+
+	p.expect('>')
+	return
+}
+
+// PackageInit = unquotedString unquotedString int .
+func (p *parser) parsePackageInit() PackageInit {
+	name := p.parseUnquotedString()
+	initfunc := p.parseUnquotedString()
+	priority := int(p.parseInt())
+	return PackageInit{Name: name, InitFunc: initfunc, Priority: priority}
+}
+
+// Throw away tokens until we see a ';'. If we see a '<', attempt to parse as a type.
+func (p *parser) discardDirectiveWhileParsingTypes(pkg *types.Package) {
+	for {
+		switch p.tok {
+		case ';':
+			return
+		case '<':
+			p.parseType(p.pkg)
+		case scanner.EOF:
+			p.error("unexpected EOF")
+		default:
+			p.next()
+		}
+	}
+}
+
+// Create the package if we have parsed both the package path and package name.
+func (p *parser) maybeCreatePackage() {
+	if p.pkgname != "" && p.pkgpath != "" {
+		p.pkg = p.getPkg(p.pkgpath, p.pkgname)
+	}
+}
+
+// InitDataDirective = "v1" ";" |
+//                     "priority" int ";" |
+//                     "init" { PackageInit } ";" |
+//                     "checksum" unquotedString ";" .
+func (p *parser) parseInitDataDirective() {
+	if p.tok != scanner.Ident {
+		// unexpected token kind; panic
+		p.expect(scanner.Ident)
+	}
+
+	switch p.lit {
+	case "v1":
+		p.next()
+		p.expect(';')
+
+	case "priority":
+		p.next()
+		p.initdata.Priority = int(p.parseInt())
+		p.expect(';')
+
+	case "init":
+		p.next()
+		for p.tok != ';' && p.tok != scanner.EOF {
+			p.initdata.Inits = append(p.initdata.Inits, p.parsePackageInit())
+		}
+		p.expect(';')
+
+	case "checksum":
+		// Don't let the scanner try to parse the checksum as a number.
+		defer func(mode uint) {
+			p.scanner.Mode = mode
+		}(p.scanner.Mode)
+		p.scanner.Mode &^= scanner.ScanInts | scanner.ScanFloats
+		p.next()
+		p.parseUnquotedString()
+		p.expect(';')
+
+	default:
+		p.errorf("unexpected identifier: %q", p.lit)
+	}
+}
+
+// Directive = InitDataDirective |
+//             "package" unquotedString ";" |
+//             "pkgpath" unquotedString ";" |
+//             "import" unquotedString unquotedString string ";" |
+//             "func" Func ";" |
+//             "type" Type ";" |
+//             "var" Var ";" |
+//             "const" Const ";" .
+func (p *parser) parseDirective() {
+	if p.tok != scanner.Ident {
+		// unexpected token kind; panic
+		p.expect(scanner.Ident)
+	}
+
+	switch p.lit {
+	case "v1", "priority", "init", "checksum":
+		p.parseInitDataDirective()
+
+	case "package":
+		p.next()
+		p.pkgname = p.parseUnquotedString()
+		p.maybeCreatePackage()
+		p.expect(';')
+
+	case "pkgpath":
+		p.next()
+		p.pkgpath = p.parseUnquotedString()
+		p.maybeCreatePackage()
+		p.expect(';')
+
+	case "import":
+		p.next()
+		pkgname := p.parseUnquotedString()
+		pkgpath := p.parseUnquotedString()
+		p.getPkg(pkgpath, pkgname)
+		p.parseString()
+		p.expect(';')
+
+	case "func":
+		p.next()
+		fun := p.parseFunc(p.pkg)
+		if fun != nil {
+			p.pkg.Scope().Insert(fun)
+		}
+		p.expect(';')
+
+	case "type":
+		p.next()
+		p.parseType(p.pkg)
+		p.expect(';')
+
+	case "var":
+		p.next()
+		v := p.parseVar(p.pkg)
+		p.pkg.Scope().Insert(v)
+		p.expect(';')
+
+	case "const":
+		p.next()
+		c := p.parseConst(p.pkg)
+		p.pkg.Scope().Insert(c)
+		p.expect(';')
+
+	default:
+		p.errorf("unexpected identifier: %q", p.lit)
+	}
+}
+
+// Package = { Directive } .
+func (p *parser) parsePackage() *types.Package {
+	for p.tok != scanner.EOF {
+		p.parseDirective()
+	}
+	for _, typ := range p.typeMap {
+		if it, ok := typ.(*types.Interface); ok {
+			it.Complete()
+		}
+	}
+	p.pkg.MarkComplete()
+	return p.pkg
+}
+
+// InitData = { InitDataDirective } .
+func (p *parser) parseInitData() {
+	for p.tok != scanner.EOF {
+		p.parseInitDataDirective()
+	}
+}
diff --git a/libgo/go/go/internal/gccgoimporter/parser_test.go b/libgo/go/go/internal/gccgoimporter/parser_test.go
new file mode 100644
index 00000000000..b96486f20ad
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/parser_test.go
@@ -0,0 +1,72 @@
+// Copyright 2013 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 gccgoimporter
+
+import (
+	"bytes"
+	"go/types"
+	"strings"
+	"testing"
+	"text/scanner"
+)
+
+var typeParserTests = []struct {
+	id, typ, want, underlying, methods string
+}{
+	{id: "foo", typ: "<type -1>", want: "int8"},
+	{id: "foo", typ: "<type 1 *<type -19>>", want: "*error"},
+	{id: "foo", typ: "<type 1 *any>", want: "unsafe.Pointer"},
+	{id: "foo", typ: "<type 1 \"Bar\" <type 2 *<type 1>>>", want: "foo.Bar", underlying: "*foo.Bar"},
+	{id: "foo", typ: "<type 1 \"bar.Foo\" \"bar\" <type -1> func (? <type 1>) M (); >", want: "bar.Foo", underlying: "int8", methods: "func (bar.Foo).M()"},
+	{id: "foo", typ: "<type 1 \".bar.foo\" \"bar\" <type -1>>", want: "bar.foo", underlying: "int8"},
+	{id: "foo", typ: "<type 1 []<type -1>>", want: "[]int8"},
+	{id: "foo", typ: "<type 1 [42]<type -1>>", want: "[42]int8"},
+	{id: "foo", typ: "<type 1 map [<type -1>] <type -2>>", want: "map[int8]int16"},
+	{id: "foo", typ: "<type 1 chan <type -1>>", want: "chan int8"},
+	{id: "foo", typ: "<type 1 chan <- <type -1>>", want: "<-chan int8"},
+	{id: "foo", typ: "<type 1 chan -< <type -1>>", want: "chan<- int8"},
+	{id: "foo", typ: "<type 1 struct { I8 <type -1>; I16 <type -2> \"i16\"; }>", want: "struct{I8 int8; I16 int16 \"i16\"}"},
+	{id: "foo", typ: "<type 1 interface { Foo (a <type -1>, b <type -2>) <type -1>; Bar (? <type -2>, ? ...<type -1>) (? <type -2>, ? <type -1>); Baz (); }>", want: "interface{Bar(int16, ...int8) (int16, int8); Baz(); Foo(a int8, b int16) int8}"},
+	{id: "foo", typ: "<type 1 (? <type -1>) <type -2>>", want: "func(int8) int16"},
+}
+
+func TestTypeParser(t *testing.T) {
+	for _, test := range typeParserTests {
+		var p parser
+		p.init("test.gox", strings.NewReader(test.typ), make(map[string]*types.Package))
+		p.pkgname = test.id
+		p.pkgpath = test.id
+		p.maybeCreatePackage()
+		typ := p.parseType(p.pkg)
+
+		if p.tok != scanner.EOF {
+			t.Errorf("expected full parse, stopped at %q", p.lit)
+		}
+
+		got := typ.String()
+		if got != test.want {
+			t.Errorf("got type %q, expected %q", got, test.want)
+		}
+
+		if test.underlying != "" {
+			underlying := typ.Underlying().String()
+			if underlying != test.underlying {
+				t.Errorf("got underlying type %q, expected %q", underlying, test.underlying)
+			}
+		}
+
+		if test.methods != "" {
+			nt := typ.(*types.Named)
+			var buf bytes.Buffer
+			for i := 0; i != nt.NumMethods(); i++ {
+				buf.WriteString(nt.Method(i).String())
+			}
+			methods := buf.String()
+			if methods != test.methods {
+				t.Errorf("got methods %q, expected %q", methods, test.methods)
+			}
+		}
+	}
+}
diff --git a/libgo/go/go/internal/gccgoimporter/testdata/complexnums.go b/libgo/go/go/internal/gccgoimporter/testdata/complexnums.go
new file mode 100644
index 00000000000..a51b6b01c0b
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/testdata/complexnums.go
@@ -0,0 +1,6 @@
+package complexnums
+
+const NN = -1 - 1i
+const NP = -1 + 1i
+const PN = 1 - 1i
+const PP = 1 + 1i
diff --git a/libgo/go/go/internal/gccgoimporter/testdata/imports.go b/libgo/go/go/internal/gccgoimporter/testdata/imports.go
new file mode 100644
index 00000000000..7907316a607
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/testdata/imports.go
@@ -0,0 +1,5 @@
+package imports
+
+import "fmt"
+
+var Hello = fmt.Sprintf("Hello, world")
diff --git a/libgo/go/go/internal/gccgoimporter/testdata/pointer.go b/libgo/go/go/internal/gccgoimporter/testdata/pointer.go
new file mode 100644
index 00000000000..4ebc67137d6
--- /dev/null
+++ b/libgo/go/go/internal/gccgoimporter/testdata/pointer.go
@@ -0,0 +1,3 @@
+package pointer
+
+type Int8Ptr *int8
diff --git a/libgo/go/go/internal/gcimporter/exportdata.go b/libgo/go/go/internal/gcimporter/exportdata.go
new file mode 100644
index 00000000000..657742bb6d7
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/exportdata.go
@@ -0,0 +1,108 @@
+// 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.
+
+// This file implements FindExportData.
+
+package gcimporter
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
+	// See $GOROOT/include/ar.h.
+	hdr := make([]byte, 16+12+6+6+8+10+2)
+	_, err = io.ReadFull(r, hdr)
+	if err != nil {
+		return
+	}
+	// leave for debugging
+	if false {
+		fmt.Printf("header: %s", hdr)
+	}
+	s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
+	size, err = strconv.Atoi(s)
+	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
+		err = errors.New("invalid archive header")
+		return
+	}
+	name = strings.TrimSpace(string(hdr[:16]))
+	return
+}
+
+// FindExportData positions the reader r at the beginning of the
+// export data section of an underlying GC-created object/archive
+// file by reading from it. The reader must be positioned at the
+// start of the file before calling this function.
+//
+func FindExportData(r *bufio.Reader) (err error) {
+	// Read first line to make sure this is an object file.
+	line, err := r.ReadSlice('\n')
+	if err != nil {
+		return
+	}
+	if string(line) == "!<arch>\n" {
+		// Archive file. Scan to __.PKGDEF.
+		var name string
+		var size int
+		if name, size, err = readGopackHeader(r); err != nil {
+			return
+		}
+
+		// Optional leading __.GOSYMDEF or __.SYMDEF.
+		// Read and discard.
+		if name == "__.SYMDEF" || name == "__.GOSYMDEF" {
+			const block = 4096
+			tmp := make([]byte, block)
+			for size > 0 {
+				n := size
+				if n > block {
+					n = block
+				}
+				if _, err = io.ReadFull(r, tmp[:n]); err != nil {
+					return
+				}
+				size -= n
+			}
+
+			if name, size, err = readGopackHeader(r); err != nil {
+				return
+			}
+		}
+
+		// First real entry should be __.PKGDEF.
+		if name != "__.PKGDEF" {
+			err = errors.New("go archive is missing __.PKGDEF")
+			return
+		}
+
+		// Read first line of __.PKGDEF data, so that line
+		// is once again the first line of the input.
+		if line, err = r.ReadSlice('\n'); err != nil {
+			return
+		}
+	}
+
+	// Now at __.PKGDEF in archive or still at beginning of file.
+	// Either way, line should begin with "go object ".
+	if !strings.HasPrefix(string(line), "go object ") {
+		err = errors.New("not a go object file")
+		return
+	}
+
+	// Skip over object header to export data.
+	// Begins after first line with $$.
+	for line[0] != '$' {
+		if line, err = r.ReadSlice('\n'); err != nil {
+			return
+		}
+	}
+
+	return
+}
diff --git a/libgo/go/go/internal/gcimporter/gcimporter.go b/libgo/go/go/internal/gcimporter/gcimporter.go
new file mode 100644
index 00000000000..1d485cf9cbf
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/gcimporter.go
@@ -0,0 +1,991 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gcimporter implements Import for gc-generated object files.
+package gcimporter // import "go/internal/gcimporter"
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"go/build"
+	"go/token"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"text/scanner"
+
+	exact "go/constant"
+	"go/types"
+)
+
+// debugging/development support
+const debug = false
+
+var pkgExts = [...]string{".a", ".o"}
+
+// FindPkg returns the filename and unique package id for an import
+// path based on package information provided by build.Import (using
+// the build.Default build.Context).
+// If no file was found, an empty filename is returned.
+//
+func FindPkg(path, srcDir string) (filename, id string) {
+	if len(path) == 0 {
+		return
+	}
+
+	id = path
+	var noext string
+	switch {
+	default:
+		// "x" -> "$GOPATH/pkg/$GOOS_$GOARCH/x.ext", "x"
+		// Don't require the source files to be present.
+		bp, _ := build.Import(path, srcDir, build.FindOnly|build.AllowBinary)
+		if bp.PkgObj == "" {
+			return
+		}
+		noext = strings.TrimSuffix(bp.PkgObj, ".a")
+
+	case build.IsLocalImport(path):
+		// "./x" -> "/this/directory/x.ext", "/this/directory/x"
+		noext = filepath.Join(srcDir, path)
+		id = noext
+
+	case filepath.IsAbs(path):
+		// for completeness only - go/build.Import
+		// does not support absolute imports
+		// "/x" -> "/x.ext", "/x"
+		noext = path
+	}
+
+	// try extensions
+	for _, ext := range pkgExts {
+		filename = noext + ext
+		if f, err := os.Stat(filename); err == nil && !f.IsDir() {
+			return
+		}
+	}
+
+	filename = "" // not found
+	return
+}
+
+// ImportData imports a package by reading the gc-generated export data,
+// adds the corresponding package object to the packages map indexed by id,
+// and returns the object.
+//
+// The packages map must contains all packages already imported. The data
+// reader position must be the beginning of the export data section. The
+// filename is only used in error messages.
+//
+// If packages[id] contains the completely imported package, that package
+// can be used directly, and there is no need to call this function (but
+// there is also no harm but for extra time used).
+//
+func ImportData(packages map[string]*types.Package, filename, id string, data io.Reader) (pkg *types.Package, err error) {
+	// support for parser error handling
+	defer func() {
+		switch r := recover().(type) {
+		case nil:
+			// nothing to do
+		case importError:
+			err = r
+		default:
+			panic(r) // internal error
+		}
+	}()
+
+	var p parser
+	p.init(filename, id, data, packages)
+	pkg = p.parseExport()
+
+	return
+}
+
+// Import imports a gc-generated package given its import path, adds the
+// corresponding package object to the packages map, and returns the object.
+// Local import paths are interpreted relative to the current working directory.
+// The packages map must contain all packages already imported.
+//
+func Import(packages map[string]*types.Package, path string) (pkg *types.Package, err error) {
+	// package "unsafe" is handled by the type checker
+	if path == "unsafe" {
+		panic(`gcimporter.Import called for package "unsafe"`)
+	}
+
+	srcDir := "."
+	if build.IsLocalImport(path) {
+		srcDir, err = os.Getwd()
+		if err != nil {
+			return
+		}
+	}
+
+	filename, id := FindPkg(path, srcDir)
+	if filename == "" {
+		err = fmt.Errorf("can't find import: %s", id)
+		return
+	}
+
+	// no need to re-import if the package was imported completely before
+	if pkg = packages[id]; pkg != nil && pkg.Complete() {
+		return
+	}
+
+	// open file
+	f, err := os.Open(filename)
+	if err != nil {
+		return
+	}
+	defer func() {
+		f.Close()
+		if err != nil {
+			// add file name to error
+			err = fmt.Errorf("reading export data: %s: %v", filename, err)
+		}
+	}()
+
+	buf := bufio.NewReader(f)
+	if err = FindExportData(buf); err != nil {
+		return
+	}
+
+	pkg, err = ImportData(packages, filename, id, buf)
+
+	return
+}
+
+// ----------------------------------------------------------------------------
+// Parser
+
+// TODO(gri) Imported objects don't have position information.
+//           Ideally use the debug table line info; alternatively
+//           create some fake position (or the position of the
+//           import). That way error messages referring to imported
+//           objects can print meaningful information.
+
+// parser parses the exports inside a gc compiler-produced
+// object/archive file and populates its scope with the results.
+type parser struct {
+	scanner    scanner.Scanner
+	tok        rune                      // current token
+	lit        string                    // literal string; only valid for Ident, Int, String tokens
+	id         string                    // package id of imported package
+	sharedPkgs map[string]*types.Package // package id -> package object (across importer)
+	localPkgs  map[string]*types.Package // package id -> package object (just this package)
+}
+
+func (p *parser) init(filename, id string, src io.Reader, packages map[string]*types.Package) {
+	p.scanner.Init(src)
+	p.scanner.Error = func(_ *scanner.Scanner, msg string) { p.error(msg) }
+	p.scanner.Mode = scanner.ScanIdents | scanner.ScanInts | scanner.ScanChars | scanner.ScanStrings | scanner.ScanComments | scanner.SkipComments
+	p.scanner.Whitespace = 1<<'\t' | 1<<' '
+	p.scanner.Filename = filename // for good error messages
+	p.next()
+	p.id = id
+	p.sharedPkgs = packages
+	if debug {
+		// check consistency of packages map
+		for _, pkg := range packages {
+			if pkg.Name() == "" {
+				fmt.Printf("no package name for %s\n", pkg.Path())
+			}
+		}
+	}
+}
+
+func (p *parser) next() {
+	p.tok = p.scanner.Scan()
+	switch p.tok {
+	case scanner.Ident, scanner.Int, scanner.Char, scanner.String, '·':
+		p.lit = p.scanner.TokenText()
+	default:
+		p.lit = ""
+	}
+	if debug {
+		fmt.Printf("%s: %q -> %q\n", scanner.TokenString(p.tok), p.scanner.TokenText(), p.lit)
+	}
+}
+
+func declTypeName(pkg *types.Package, name string) *types.TypeName {
+	scope := pkg.Scope()
+	if obj := scope.Lookup(name); obj != nil {
+		return obj.(*types.TypeName)
+	}
+	obj := types.NewTypeName(token.NoPos, pkg, name, nil)
+	// a named type may be referred to before the underlying type
+	// is known - set it up
+	types.NewNamed(obj, nil, nil)
+	scope.Insert(obj)
+	return obj
+}
+
+// ----------------------------------------------------------------------------
+// Error handling
+
+// Internal errors are boxed as importErrors.
+type importError struct {
+	pos scanner.Position
+	err error
+}
+
+func (e importError) Error() string {
+	return fmt.Sprintf("import error %s (byte offset = %d): %s", e.pos, e.pos.Offset, e.err)
+}
+
+func (p *parser) error(err interface{}) {
+	if s, ok := err.(string); ok {
+		err = errors.New(s)
+	}
+	// panic with a runtime.Error if err is not an error
+	panic(importError{p.scanner.Pos(), err.(error)})
+}
+
+func (p *parser) errorf(format string, args ...interface{}) {
+	p.error(fmt.Sprintf(format, args...))
+}
+
+func (p *parser) expect(tok rune) string {
+	lit := p.lit
+	if p.tok != tok {
+		p.errorf("expected %s, got %s (%s)", scanner.TokenString(tok), scanner.TokenString(p.tok), lit)
+	}
+	p.next()
+	return lit
+}
+
+func (p *parser) expectSpecial(tok string) {
+	sep := 'x' // not white space
+	i := 0
+	for i < len(tok) && p.tok == rune(tok[i]) && sep > ' ' {
+		sep = p.scanner.Peek() // if sep <= ' ', there is white space before the next token
+		p.next()
+		i++
+	}
+	if i < len(tok) {
+		p.errorf("expected %q, got %q", tok, tok[0:i])
+	}
+}
+
+func (p *parser) expectKeyword(keyword string) {
+	lit := p.expect(scanner.Ident)
+	if lit != keyword {
+		p.errorf("expected keyword %s, got %q", keyword, lit)
+	}
+}
+
+// ----------------------------------------------------------------------------
+// Qualified and unqualified names
+
+// PackageId = string_lit .
+//
+func (p *parser) parsePackageId() string {
+	id, err := strconv.Unquote(p.expect(scanner.String))
+	if err != nil {
+		p.error(err)
+	}
+	// id == "" stands for the imported package id
+	// (only known at time of package installation)
+	if id == "" {
+		id = p.id
+	}
+	return id
+}
+
+// PackageName = ident .
+//
+func (p *parser) parsePackageName() string {
+	return p.expect(scanner.Ident)
+}
+
+// dotIdentifier = ( ident | '·' ) { ident | int | '·' } .
+func (p *parser) parseDotIdent() string {
+	ident := ""
+	if p.tok != scanner.Int {
+		sep := 'x' // not white space
+		for (p.tok == scanner.Ident || p.tok == scanner.Int || p.tok == '·') && sep > ' ' {
+			ident += p.lit
+			sep = p.scanner.Peek() // if sep <= ' ', there is white space before the next token
+			p.next()
+		}
+	}
+	if ident == "" {
+		p.expect(scanner.Ident) // use expect() for error handling
+	}
+	return ident
+}
+
+// QualifiedName = "@" PackageId "." ( "?" | dotIdentifier ) .
+//
+func (p *parser) parseQualifiedName() (id, name string) {
+	p.expect('@')
+	id = p.parsePackageId()
+	p.expect('.')
+	// Per rev f280b8a485fd (10/2/2013), qualified names may be used for anonymous fields.
+	if p.tok == '?' {
+		p.next()
+	} else {
+		name = p.parseDotIdent()
+	}
+	return
+}
+
+// getPkg returns the package for a given id. If the package is
+// not found but we have a package name, create the package and
+// add it to the p.localPkgs and p.sharedPkgs maps.
+//
+// id identifies a package, usually by a canonical package path like
+// "encoding/json" but possibly by a non-canonical import path like
+// "./json".
+//
+func (p *parser) getPkg(id, name string) *types.Package {
+	// package unsafe is not in the packages maps - handle explicitly
+	if id == "unsafe" {
+		return types.Unsafe
+	}
+
+	pkg := p.localPkgs[id]
+	if pkg == nil && name != "" {
+		// first import of id from this package
+		pkg = p.sharedPkgs[id]
+		if pkg == nil {
+			// first import of id by this importer
+			pkg = types.NewPackage(id, name)
+			p.sharedPkgs[id] = pkg
+		}
+
+		if p.localPkgs == nil {
+			p.localPkgs = make(map[string]*types.Package)
+		}
+		p.localPkgs[id] = pkg
+	}
+	return pkg
+}
+
+// parseExportedName is like parseQualifiedName, but
+// the package id is resolved to an imported *types.Package.
+//
+func (p *parser) parseExportedName() (pkg *types.Package, name string) {
+	id, name := p.parseQualifiedName()
+	pkg = p.getPkg(id, "")
+	if pkg == nil {
+		p.errorf("%s package not found", id)
+	}
+	return
+}
+
+// ----------------------------------------------------------------------------
+// Types
+
+// BasicType = identifier .
+//
+func (p *parser) parseBasicType() types.Type {
+	id := p.expect(scanner.Ident)
+	obj := types.Universe.Lookup(id)
+	if obj, ok := obj.(*types.TypeName); ok {
+		return obj.Type()
+	}
+	p.errorf("not a basic type: %s", id)
+	return nil
+}
+
+// ArrayType = "[" int_lit "]" Type .
+//
+func (p *parser) parseArrayType() types.Type {
+	// "[" already consumed and lookahead known not to be "]"
+	lit := p.expect(scanner.Int)
+	p.expect(']')
+	elem := p.parseType()
+	n, err := strconv.ParseInt(lit, 10, 64)
+	if err != nil {
+		p.error(err)
+	}
+	return types.NewArray(elem, n)
+}
+
+// MapType = "map" "[" Type "]" Type .
+//
+func (p *parser) parseMapType() types.Type {
+	p.expectKeyword("map")
+	p.expect('[')
+	key := p.parseType()
+	p.expect(']')
+	elem := p.parseType()
+	return types.NewMap(key, elem)
+}
+
+// Name = identifier | "?" | QualifiedName .
+//
+// If materializePkg is set, the returned package is guaranteed to be set.
+// For fully qualified names, the returned package may be a fake package
+// (without name, scope, and not in the p.sharedPkgs map), created for the
+// sole purpose of providing a package path. Fake packages are created
+// when the package id is not found in the p.sharedPkgs map; in that case
+// we cannot create a real package because we don't have a package name.
+// For non-qualified names, the returned package is the imported package.
+//
+func (p *parser) parseName(materializePkg bool) (pkg *types.Package, name string) {
+	switch p.tok {
+	case scanner.Ident:
+		pkg = p.sharedPkgs[p.id]
+		name = p.lit
+		p.next()
+	case '?':
+		// anonymous
+		pkg = p.sharedPkgs[p.id]
+		p.next()
+	case '@':
+		// exported name prefixed with package path
+		var id string
+		id, name = p.parseQualifiedName()
+		if materializePkg {
+			// we don't have a package name - if the package
+			// doesn't exist yet, create a fake package instead
+			pkg = p.getPkg(id, "")
+			if pkg == nil {
+				pkg = types.NewPackage(id, "")
+			}
+		}
+	default:
+		p.error("name expected")
+	}
+	return
+}
+
+func deref(typ types.Type) types.Type {
+	if p, _ := typ.(*types.Pointer); p != nil {
+		return p.Elem()
+	}
+	return typ
+}
+
+// Field = Name Type [ string_lit ] .
+//
+func (p *parser) parseField() (*types.Var, string) {
+	pkg, name := p.parseName(true)
+	typ := p.parseType()
+	anonymous := false
+	if name == "" {
+		// anonymous field - typ must be T or *T and T must be a type name
+		switch typ := deref(typ).(type) {
+		case *types.Basic: // basic types are named types
+			pkg = nil
+			name = typ.Name()
+		case *types.Named:
+			name = typ.Obj().Name()
+		default:
+			p.errorf("anonymous field expected")
+		}
+		anonymous = true
+	}
+	tag := ""
+	if p.tok == scanner.String {
+		s := p.expect(scanner.String)
+		var err error
+		tag, err = strconv.Unquote(s)
+		if err != nil {
+			p.errorf("invalid struct tag %s: %s", s, err)
+		}
+	}
+	return types.NewField(token.NoPos, pkg, name, typ, anonymous), tag
+}
+
+// StructType = "struct" "{" [ FieldList ] "}" .
+// FieldList  = Field { ";" Field } .
+//
+func (p *parser) parseStructType() types.Type {
+	var fields []*types.Var
+	var tags []string
+
+	p.expectKeyword("struct")
+	p.expect('{')
+	for i := 0; p.tok != '}' && p.tok != scanner.EOF; i++ {
+		if i > 0 {
+			p.expect(';')
+		}
+		fld, tag := p.parseField()
+		if tag != "" && tags == nil {
+			tags = make([]string, i)
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+		fields = append(fields, fld)
+	}
+	p.expect('}')
+
+	return types.NewStruct(fields, tags)
+}
+
+// Parameter = ( identifier | "?" ) [ "..." ] Type [ string_lit ] .
+//
+func (p *parser) parseParameter() (par *types.Var, isVariadic bool) {
+	_, name := p.parseName(false)
+	// remove gc-specific parameter numbering
+	if i := strings.Index(name, "·"); i >= 0 {
+		name = name[:i]
+	}
+	if p.tok == '.' {
+		p.expectSpecial("...")
+		isVariadic = true
+	}
+	typ := p.parseType()
+	if isVariadic {
+		typ = types.NewSlice(typ)
+	}
+	// ignore argument tag (e.g. "noescape")
+	if p.tok == scanner.String {
+		p.next()
+	}
+	// TODO(gri) should we provide a package?
+	par = types.NewVar(token.NoPos, nil, name, typ)
+	return
+}
+
+// Parameters    = "(" [ ParameterList ] ")" .
+// ParameterList = { Parameter "," } Parameter .
+//
+func (p *parser) parseParameters() (list []*types.Var, isVariadic bool) {
+	p.expect('(')
+	for p.tok != ')' && p.tok != scanner.EOF {
+		if len(list) > 0 {
+			p.expect(',')
+		}
+		par, variadic := p.parseParameter()
+		list = append(list, par)
+		if variadic {
+			if isVariadic {
+				p.error("... not on final argument")
+			}
+			isVariadic = true
+		}
+	}
+	p.expect(')')
+
+	return
+}
+
+// Signature = Parameters [ Result ] .
+// Result    = Type | Parameters .
+//
+func (p *parser) parseSignature(recv *types.Var) *types.Signature {
+	params, isVariadic := p.parseParameters()
+
+	// optional result type
+	var results []*types.Var
+	if p.tok == '(' {
+		var variadic bool
+		results, variadic = p.parseParameters()
+		if variadic {
+			p.error("... not permitted on result type")
+		}
+	}
+
+	return types.NewSignature(recv, types.NewTuple(params...), types.NewTuple(results...), isVariadic)
+}
+
+// InterfaceType = "interface" "{" [ MethodList ] "}" .
+// MethodList    = Method { ";" Method } .
+// Method        = Name Signature .
+//
+// The methods of embedded interfaces are always "inlined"
+// by the compiler and thus embedded interfaces are never
+// visible in the export data.
+//
+func (p *parser) parseInterfaceType() types.Type {
+	var methods []*types.Func
+
+	p.expectKeyword("interface")
+	p.expect('{')
+	for i := 0; p.tok != '}' && p.tok != scanner.EOF; i++ {
+		if i > 0 {
+			p.expect(';')
+		}
+		pkg, name := p.parseName(true)
+		sig := p.parseSignature(nil)
+		methods = append(methods, types.NewFunc(token.NoPos, pkg, name, sig))
+	}
+	p.expect('}')
+
+	// Complete requires the type's embedded interfaces to be fully defined,
+	// but we do not define any
+	return types.NewInterface(methods, nil).Complete()
+}
+
+// ChanType = ( "chan" [ "<-" ] | "<-" "chan" ) Type .
+//
+func (p *parser) parseChanType() types.Type {
+	dir := types.SendRecv
+	if p.tok == scanner.Ident {
+		p.expectKeyword("chan")
+		if p.tok == '<' {
+			p.expectSpecial("<-")
+			dir = types.SendOnly
+		}
+	} else {
+		p.expectSpecial("<-")
+		p.expectKeyword("chan")
+		dir = types.RecvOnly
+	}
+	elem := p.parseType()
+	return types.NewChan(dir, elem)
+}
+
+// Type =
+//	BasicType | TypeName | ArrayType | SliceType | StructType |
+//      PointerType | FuncType | InterfaceType | MapType | ChanType |
+//      "(" Type ")" .
+//
+// BasicType   = ident .
+// TypeName    = ExportedName .
+// SliceType   = "[" "]" Type .
+// PointerType = "*" Type .
+// FuncType    = "func" Signature .
+//
+func (p *parser) parseType() types.Type {
+	switch p.tok {
+	case scanner.Ident:
+		switch p.lit {
+		default:
+			return p.parseBasicType()
+		case "struct":
+			return p.parseStructType()
+		case "func":
+			// FuncType
+			p.next()
+			return p.parseSignature(nil)
+		case "interface":
+			return p.parseInterfaceType()
+		case "map":
+			return p.parseMapType()
+		case "chan":
+			return p.parseChanType()
+		}
+	case '@':
+		// TypeName
+		pkg, name := p.parseExportedName()
+		return declTypeName(pkg, name).Type()
+	case '[':
+		p.next() // look ahead
+		if p.tok == ']' {
+			// SliceType
+			p.next()
+			return types.NewSlice(p.parseType())
+		}
+		return p.parseArrayType()
+	case '*':
+		// PointerType
+		p.next()
+		return types.NewPointer(p.parseType())
+	case '<':
+		return p.parseChanType()
+	case '(':
+		// "(" Type ")"
+		p.next()
+		typ := p.parseType()
+		p.expect(')')
+		return typ
+	}
+	p.errorf("expected type, got %s (%q)", scanner.TokenString(p.tok), p.lit)
+	return nil
+}
+
+// ----------------------------------------------------------------------------
+// Declarations
+
+// ImportDecl = "import" PackageName PackageId .
+//
+func (p *parser) parseImportDecl() {
+	p.expectKeyword("import")
+	name := p.parsePackageName()
+	p.getPkg(p.parsePackageId(), name)
+}
+
+// int_lit = [ "+" | "-" ] { "0" ... "9" } .
+//
+func (p *parser) parseInt() string {
+	s := ""
+	switch p.tok {
+	case '-':
+		s = "-"
+		p.next()
+	case '+':
+		p.next()
+	}
+	return s + p.expect(scanner.Int)
+}
+
+// number = int_lit [ "p" int_lit ] .
+//
+func (p *parser) parseNumber() (typ *types.Basic, val exact.Value) {
+	// mantissa
+	mant := exact.MakeFromLiteral(p.parseInt(), token.INT, 0)
+	if mant == nil {
+		panic("invalid mantissa")
+	}
+
+	if p.lit == "p" {
+		// exponent (base 2)
+		p.next()
+		exp, err := strconv.ParseInt(p.parseInt(), 10, 0)
+		if err != nil {
+			p.error(err)
+		}
+		if exp < 0 {
+			denom := exact.MakeInt64(1)
+			denom = exact.Shift(denom, token.SHL, uint(-exp))
+			typ = types.Typ[types.UntypedFloat]
+			val = exact.BinaryOp(mant, token.QUO, denom)
+			return
+		}
+		if exp > 0 {
+			mant = exact.Shift(mant, token.SHL, uint(exp))
+		}
+		typ = types.Typ[types.UntypedFloat]
+		val = mant
+		return
+	}
+
+	typ = types.Typ[types.UntypedInt]
+	val = mant
+	return
+}
+
+// ConstDecl   = "const" ExportedName [ Type ] "=" Literal .
+// Literal     = bool_lit | int_lit | float_lit | complex_lit | rune_lit | string_lit .
+// bool_lit    = "true" | "false" .
+// complex_lit = "(" float_lit "+" float_lit "i" ")" .
+// rune_lit    = "(" int_lit "+" int_lit ")" .
+// string_lit  = `"` { unicode_char } `"` .
+//
+func (p *parser) parseConstDecl() {
+	p.expectKeyword("const")
+	pkg, name := p.parseExportedName()
+
+	var typ0 types.Type
+	if p.tok != '=' {
+		typ0 = p.parseType()
+	}
+
+	p.expect('=')
+	var typ types.Type
+	var val exact.Value
+	switch p.tok {
+	case scanner.Ident:
+		// bool_lit
+		if p.lit != "true" && p.lit != "false" {
+			p.error("expected true or false")
+		}
+		typ = types.Typ[types.UntypedBool]
+		val = exact.MakeBool(p.lit == "true")
+		p.next()
+
+	case '-', scanner.Int:
+		// int_lit
+		typ, val = p.parseNumber()
+
+	case '(':
+		// complex_lit or rune_lit
+		p.next()
+		if p.tok == scanner.Char {
+			p.next()
+			p.expect('+')
+			typ = types.Typ[types.UntypedRune]
+			_, val = p.parseNumber()
+			p.expect(')')
+			break
+		}
+		_, re := p.parseNumber()
+		p.expect('+')
+		_, im := p.parseNumber()
+		p.expectKeyword("i")
+		p.expect(')')
+		typ = types.Typ[types.UntypedComplex]
+		val = exact.BinaryOp(re, token.ADD, exact.MakeImag(im))
+
+	case scanner.Char:
+		// rune_lit
+		typ = types.Typ[types.UntypedRune]
+		val = exact.MakeFromLiteral(p.lit, token.CHAR, 0)
+		p.next()
+
+	case scanner.String:
+		// string_lit
+		typ = types.Typ[types.UntypedString]
+		val = exact.MakeFromLiteral(p.lit, token.STRING, 0)
+		p.next()
+
+	default:
+		p.errorf("expected literal got %s", scanner.TokenString(p.tok))
+	}
+
+	if typ0 == nil {
+		typ0 = typ
+	}
+
+	pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, typ0, val))
+}
+
+// TypeDecl = "type" ExportedName Type .
+//
+func (p *parser) parseTypeDecl() {
+	p.expectKeyword("type")
+	pkg, name := p.parseExportedName()
+	obj := declTypeName(pkg, name)
+
+	// The type object may have been imported before and thus already
+	// have a type associated with it. We still need to parse the type
+	// structure, but throw it away if the object already has a type.
+	// This ensures that all imports refer to the same type object for
+	// a given type declaration.
+	typ := p.parseType()
+
+	if name := obj.Type().(*types.Named); name.Underlying() == nil {
+		name.SetUnderlying(typ)
+	}
+}
+
+// VarDecl = "var" ExportedName Type .
+//
+func (p *parser) parseVarDecl() {
+	p.expectKeyword("var")
+	pkg, name := p.parseExportedName()
+	typ := p.parseType()
+	pkg.Scope().Insert(types.NewVar(token.NoPos, pkg, name, typ))
+}
+
+// Func = Signature [ Body ] .
+// Body = "{" ... "}" .
+//
+func (p *parser) parseFunc(recv *types.Var) *types.Signature {
+	sig := p.parseSignature(recv)
+	if p.tok == '{' {
+		p.next()
+		for i := 1; i > 0; p.next() {
+			switch p.tok {
+			case '{':
+				i++
+			case '}':
+				i--
+			}
+		}
+	}
+	return sig
+}
+
+// MethodDecl = "func" Receiver Name Func .
+// Receiver   = "(" ( identifier | "?" ) [ "*" ] ExportedName ")" .
+//
+func (p *parser) parseMethodDecl() {
+	// "func" already consumed
+	p.expect('(')
+	recv, _ := p.parseParameter() // receiver
+	p.expect(')')
+
+	// determine receiver base type object
+	base := deref(recv.Type()).(*types.Named)
+
+	// parse method name, signature, and possibly inlined body
+	_, name := p.parseName(true)
+	sig := p.parseFunc(recv)
+
+	// methods always belong to the same package as the base type object
+	pkg := base.Obj().Pkg()
+
+	// add method to type unless type was imported before
+	// and method exists already
+	// TODO(gri) This leads to a quadratic algorithm - ok for now because method counts are small.
+	base.AddMethod(types.NewFunc(token.NoPos, pkg, name, sig))
+}
+
+// FuncDecl = "func" ExportedName Func .
+//
+func (p *parser) parseFuncDecl() {
+	// "func" already consumed
+	pkg, name := p.parseExportedName()
+	typ := p.parseFunc(nil)
+	pkg.Scope().Insert(types.NewFunc(token.NoPos, pkg, name, typ))
+}
+
+// Decl = [ ImportDecl | ConstDecl | TypeDecl | VarDecl | FuncDecl | MethodDecl ] "\n" .
+//
+func (p *parser) parseDecl() {
+	if p.tok == scanner.Ident {
+		switch p.lit {
+		case "import":
+			p.parseImportDecl()
+		case "const":
+			p.parseConstDecl()
+		case "type":
+			p.parseTypeDecl()
+		case "var":
+			p.parseVarDecl()
+		case "func":
+			p.next() // look ahead
+			if p.tok == '(' {
+				p.parseMethodDecl()
+			} else {
+				p.parseFuncDecl()
+			}
+		}
+	}
+	p.expect('\n')
+}
+
+// ----------------------------------------------------------------------------
+// Export
+
+// Export        = "PackageClause { Decl } "$$" .
+// PackageClause = "package" PackageName [ "safe" ] "\n" .
+//
+func (p *parser) parseExport() *types.Package {
+	p.expectKeyword("package")
+	name := p.parsePackageName()
+	if p.tok == scanner.Ident && p.lit == "safe" {
+		// package was compiled with -u option - ignore
+		p.next()
+	}
+	p.expect('\n')
+
+	pkg := p.getPkg(p.id, name)
+
+	for p.tok != '$' && p.tok != scanner.EOF {
+		p.parseDecl()
+	}
+
+	if ch := p.scanner.Peek(); p.tok != '$' || ch != '$' {
+		// don't call next()/expect() since reading past the
+		// export data may cause scanner errors (e.g. NUL chars)
+		p.errorf("expected '$$', got %s %c", scanner.TokenString(p.tok), ch)
+	}
+
+	if n := p.scanner.ErrorCount; n != 0 {
+		p.errorf("expected no scanner errors, got %d", n)
+	}
+
+	// Record all referenced packages as imports.
+	var imports []*types.Package
+	for id, pkg2 := range p.localPkgs {
+		if id == p.id {
+			continue // avoid self-edge
+		}
+		imports = append(imports, pkg2)
+	}
+	sort.Sort(byPath(imports))
+	pkg.SetImports(imports)
+
+	// package was imported completely and without errors
+	pkg.MarkComplete()
+
+	return pkg
+}
+
+type byPath []*types.Package
+
+func (a byPath) Len() int           { return len(a) }
+func (a byPath) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byPath) Less(i, j int) bool { return a[i].Path() < a[j].Path() }
diff --git a/libgo/go/go/internal/gcimporter/gcimporter_test.go b/libgo/go/go/internal/gcimporter/gcimporter_test.go
new file mode 100644
index 00000000000..07993a801f7
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/gcimporter_test.go
@@ -0,0 +1,225 @@
+// 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.
+
+package gcimporter
+
+import (
+	"fmt"
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"go/types"
+)
+
+// skipSpecialPlatforms causes the test to be skipped for platforms where
+// builders (build.golang.org) don't have access to compiled packages for
+// import.
+func skipSpecialPlatforms(t *testing.T) {
+	switch platform := runtime.GOOS + "-" + runtime.GOARCH; platform {
+	case "nacl-amd64p32",
+		"nacl-386",
+		"nacl-arm",
+		"darwin-arm",
+		"darwin-arm64":
+		t.Skipf("no compiled packages available for import on %s", platform)
+	}
+}
+
+func compile(t *testing.T, dirname, filename string) string {
+	testenv.MustHaveGoBuild(t)
+	cmd := exec.Command("go", "tool", "compile", filename)
+	cmd.Dir = dirname
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Logf("%s", out)
+		t.Fatalf("go tool compile %s failed: %s", filename, err)
+	}
+	// filename should end with ".go"
+	return filepath.Join(dirname, filename[:len(filename)-2]+"o")
+}
+
+// Use the same global imports map for all tests. The effect is
+// as if all tested packages were imported into a single package.
+var imports = make(map[string]*types.Package)
+
+func testPath(t *testing.T, path string) *types.Package {
+	t0 := time.Now()
+	pkg, err := Import(imports, path)
+	if err != nil {
+		t.Errorf("testPath(%s): %s", path, err)
+		return nil
+	}
+	t.Logf("testPath(%s): %v", path, time.Since(t0))
+	return pkg
+}
+
+const maxTime = 30 * time.Second
+
+func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
+	dirname := filepath.Join(runtime.GOROOT(), "pkg", runtime.GOOS+"_"+runtime.GOARCH, dir)
+	list, err := ioutil.ReadDir(dirname)
+	if err != nil {
+		t.Fatalf("testDir(%s): %s", dirname, err)
+	}
+	for _, f := range list {
+		if time.Now().After(endTime) {
+			t.Log("testing time used up")
+			return
+		}
+		switch {
+		case !f.IsDir():
+			// try extensions
+			for _, ext := range pkgExts {
+				if strings.HasSuffix(f.Name(), ext) {
+					name := f.Name()[0 : len(f.Name())-len(ext)] // remove extension
+					if testPath(t, filepath.Join(dir, name)) != nil {
+						nimports++
+					}
+				}
+			}
+		case f.IsDir():
+			nimports += testDir(t, filepath.Join(dir, f.Name()), endTime)
+		}
+	}
+	return
+}
+
+func TestImport(t *testing.T) {
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	if outFn := compile(t, "testdata", "exports.go"); outFn != "" {
+		defer os.Remove(outFn)
+	}
+
+	nimports := 0
+	if pkg := testPath(t, "./testdata/exports"); pkg != nil {
+		nimports++
+		// The package's Imports should include all the types
+		// referenced by the exportdata, which may be more than
+		// the import statements in the package's source, but
+		// fewer than the transitive closure of dependencies.
+		want := `[package ast ("go/ast") package token ("go/token") package runtime ("runtime")]`
+		got := fmt.Sprint(pkg.Imports())
+		if got != want {
+			t.Errorf(`Package("exports").Imports() = %s, want %s`, got, want)
+		}
+	}
+	nimports += testDir(t, "", time.Now().Add(maxTime)) // installed packages
+	t.Logf("tested %d imports", nimports)
+}
+
+var importedObjectTests = []struct {
+	name string
+	want string
+}{
+	{"math.Pi", "const Pi untyped float"},
+	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
+	{"io.ReadWriter", "type ReadWriter interface{Read(p []byte) (n int, err error); Write(p []byte) (n int, err error)}"},
+	{"math.Sin", "func Sin(x float64) float64"},
+	// TODO(gri) add more tests
+}
+
+func TestImportedTypes(t *testing.T) {
+	skipSpecialPlatforms(t)
+
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	for _, test := range importedObjectTests {
+		s := strings.Split(test.name, ".")
+		if len(s) != 2 {
+			t.Fatal("inconsistent test data")
+		}
+		importPath := s[0]
+		objName := s[1]
+
+		pkg, err := Import(imports, importPath)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+
+		obj := pkg.Scope().Lookup(objName)
+		if obj == nil {
+			t.Errorf("%s: object not found", test.name)
+			continue
+		}
+
+		got := types.ObjectString(obj, types.RelativeTo(pkg))
+		if got != test.want {
+			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
+		}
+	}
+}
+
+func TestIssue5815(t *testing.T) {
+	skipSpecialPlatforms(t)
+
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	pkg, err := Import(make(map[string]*types.Package), "strings")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		obj := scope.Lookup(name)
+		if obj.Pkg() == nil {
+			t.Errorf("no pkg for %s", obj)
+		}
+		if tname, _ := obj.(*types.TypeName); tname != nil {
+			named := tname.Type().(*types.Named)
+			for i := 0; i < named.NumMethods(); i++ {
+				m := named.Method(i)
+				if m.Pkg() == nil {
+					t.Errorf("no pkg for %s", m)
+				}
+			}
+		}
+	}
+}
+
+// Smoke test to ensure that imported methods get the correct package.
+func TestCorrectMethodPackage(t *testing.T) {
+	skipSpecialPlatforms(t)
+
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	imports := make(map[string]*types.Package)
+	_, err := Import(imports, "net/http")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mutex := imports["sync"].Scope().Lookup("Mutex").(*types.TypeName).Type()
+	mset := types.NewMethodSet(types.NewPointer(mutex)) // methods of *sync.Mutex
+	sel := mset.Lookup(nil, "Lock")
+	lock := sel.Obj().(*types.Func)
+	if got, want := lock.Pkg().Path(), "sync"; got != want {
+		t.Errorf("got package path %q; want %q", got, want)
+	}
+}
diff --git a/libgo/go/go/internal/gcimporter/testdata/exports.go b/libgo/go/go/internal/gcimporter/testdata/exports.go
new file mode 100644
index 00000000000..8ee28b0942b
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/testdata/exports.go
@@ -0,0 +1,89 @@
+// 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.
+
+// This file is used to generate an object file which
+// serves as test file for gcimporter_test.go.
+
+package exports
+
+import (
+	"go/ast"
+)
+
+// Issue 3682: Correctly read dotted identifiers from export data.
+const init1 = 0
+
+func init() {}
+
+const (
+	C0 int = 0
+	C1     = 3.14159265
+	C2     = 2.718281828i
+	C3     = -123.456e-789
+	C4     = +123.456E+789
+	C5     = 1234i
+	C6     = "foo\n"
+	C7     = `bar\n`
+)
+
+type (
+	T1  int
+	T2  [10]int
+	T3  []int
+	T4  *int
+	T5  chan int
+	T6a chan<- int
+	T6b chan (<-chan int)
+	T6c chan<- (chan int)
+	T7  <-chan *ast.File
+	T8  struct{}
+	T9  struct {
+		a    int
+		b, c float32
+		d    []string `go:"tag"`
+	}
+	T10 struct {
+		T8
+		T9
+		_ *T10
+	}
+	T11 map[int]string
+	T12 interface{}
+	T13 interface {
+		m1()
+		m2(int) float32
+	}
+	T14 interface {
+		T12
+		T13
+		m3(x ...struct{}) []T9
+	}
+	T15 func()
+	T16 func(int)
+	T17 func(x int)
+	T18 func() float32
+	T19 func() (x float32)
+	T20 func(...interface{})
+	T21 struct{ next *T21 }
+	T22 struct{ link *T23 }
+	T23 struct{ link *T22 }
+	T24 *T24
+	T25 *T26
+	T26 *T27
+	T27 *T25
+	T28 func(T28) T28
+)
+
+var (
+	V0 int
+	V1 = -991.0
+)
+
+func F1()         {}
+func F2(x int)    {}
+func F3() int     { return 0 }
+func F4() float32 { return 0 }
+func F5(a, b, c int, u, v, w struct{ x, y T1 }, more ...interface{}) (p, q, r chan<- T10)
+
+func (p *T1) M1()
diff --git a/libgo/go/go/parser/error_test.go b/libgo/go/go/parser/error_test.go
index 48fb53e5b0d..1a08d5a6b11 100644
--- a/libgo/go/go/parser/error_test.go
+++ b/libgo/go/go/parser/error_test.go
@@ -34,11 +34,9 @@ import (
 
 const testdata = "testdata"
 
-var fsetErrs = token.NewFileSet()
-
 // getFile assumes that each filename occurs at most once
-func getFile(filename string) (file *token.File) {
-	fsetErrs.Iterate(func(f *token.File) bool {
+func getFile(fset *token.FileSet, filename string) (file *token.File) {
+	fset.Iterate(func(f *token.File) bool {
 		if f.Name() == filename {
 			if file != nil {
 				panic(filename + " used multiple times")
@@ -50,8 +48,8 @@ func getFile(filename string) (file *token.File) {
 	return file
 }
 
-func getPos(filename string, offset int) token.Pos {
-	if f := getFile(filename); f != nil {
+func getPos(fset *token.FileSet, filename string, offset int) token.Pos {
+	if f := getFile(fset, filename); f != nil {
 		return f.Pos(offset)
 	}
 	return token.NoPos
@@ -68,14 +66,14 @@ var errRx = regexp.MustCompile(`^/\* *ERROR *(HERE)? *"([^"]*)" *\*/$`)
 // expectedErrors collects the regular expressions of ERROR comments found
 // in files and returns them as a map of error positions to error messages.
 //
-func expectedErrors(t *testing.T, filename string, src []byte) map[token.Pos]string {
+func expectedErrors(t *testing.T, fset *token.FileSet, filename string, src []byte) map[token.Pos]string {
 	errors := make(map[token.Pos]string)
 
 	var s scanner.Scanner
 	// file was parsed already - do not add it again to the file
 	// set otherwise the position information returned here will
 	// not match the position information collected by the parser
-	s.Init(getFile(filename), src, nil, scanner.ScanComments)
+	s.Init(getFile(fset, filename), src, nil, scanner.ScanComments)
 	var prev token.Pos // position of last non-comment, non-semicolon token
 	var here token.Pos // position immediately after the token at position prev
 
@@ -109,11 +107,11 @@ func expectedErrors(t *testing.T, filename string, src []byte) map[token.Pos]str
 // compareErrors compares the map of expected error messages with the list
 // of found errors and reports discrepancies.
 //
-func compareErrors(t *testing.T, expected map[token.Pos]string, found scanner.ErrorList) {
+func compareErrors(t *testing.T, fset *token.FileSet, expected map[token.Pos]string, found scanner.ErrorList) {
 	for _, error := range found {
 		// error.Pos is a token.Position, but we want
 		// a token.Pos so we can do a map lookup
-		pos := getPos(error.Pos.Filename, error.Pos.Offset)
+		pos := getPos(fset, error.Pos.Filename, error.Pos.Offset)
 		if msg, found := expected[pos]; found {
 			// we expect a message at pos; check if it matches
 			rx, err := regexp.Compile(msg)
@@ -140,7 +138,7 @@ func compareErrors(t *testing.T, expected map[token.Pos]string, found scanner.Er
 	if len(expected) > 0 {
 		t.Errorf("%d errors not reported:", len(expected))
 		for pos, msg := range expected {
-			t.Errorf("%s: %s\n", fsetErrs.Position(pos), msg)
+			t.Errorf("%s: %s\n", fset.Position(pos), msg)
 		}
 	}
 }
@@ -152,7 +150,8 @@ func checkErrors(t *testing.T, filename string, input interface{}) {
 		return
 	}
 
-	_, err = ParseFile(fsetErrs, filename, src, DeclarationErrors|AllErrors)
+	fset := token.NewFileSet()
+	_, err = ParseFile(fset, filename, src, DeclarationErrors|AllErrors)
 	found, ok := err.(scanner.ErrorList)
 	if err != nil && !ok {
 		t.Error(err)
@@ -162,10 +161,10 @@ func checkErrors(t *testing.T, filename string, input interface{}) {
 
 	// we are expecting the following errors
 	// (collect these after parsing a file so that it is found in the file set)
-	expected := expectedErrors(t, filename, src)
+	expected := expectedErrors(t, fset, filename, src)
 
 	// verify errors returned by the parser
-	compareErrors(t, expected, found)
+	compareErrors(t, fset, expected, found)
 }
 
 func TestErrors(t *testing.T) {
diff --git a/libgo/go/go/parser/interface.go b/libgo/go/go/parser/interface.go
index 49103058b59..c6fd93240af 100644
--- a/libgo/go/go/parser/interface.go
+++ b/libgo/go/go/parser/interface.go
@@ -91,7 +91,10 @@ func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode)
 	var p parser
 	defer func() {
 		if e := recover(); e != nil {
-			_ = e.(bailout) // re-panics if it's not a bailout
+			// resume same panic if it's not a bailout
+			if _, ok := e.(bailout); !ok {
+				panic(e)
+			}
 		}
 
 		// set result values
@@ -164,14 +167,31 @@ func ParseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool, m
 	return
 }
 
-// ParseExpr is a convenience function for obtaining the AST of an expression x.
-// The position information recorded in the AST is undefined. The filename used
-// in error messages is the empty string.
+// ParseExprFrom is a convenience function for parsing an expression.
+// The arguments have the same meaning as for Parse, but the source must
+// be a valid Go (type or value) expression.
 //
-func ParseExpr(x string) (ast.Expr, error) {
+func ParseExprFrom(fset *token.FileSet, filename string, src interface{}, mode Mode) (ast.Expr, error) {
+	// get source
+	text, err := readSource(filename, src)
+	if err != nil {
+		return nil, err
+	}
+
 	var p parser
-	p.init(token.NewFileSet(), "", []byte(x), 0)
+	defer func() {
+		if e := recover(); e != nil {
+			// resume same panic if it's not a bailout
+			if _, ok := e.(bailout); !ok {
+				panic(e)
+			}
+		}
+		p.errors.Sort()
+		err = p.errors.Err()
+	}()
 
+	// parse expr
+	p.init(fset, filename, text, mode)
 	// Set up pkg-level scopes to avoid nil-pointer errors.
 	// This is not needed for a correct expression x as the
 	// parser will be ok with a nil topScope, but be cautious
@@ -196,3 +216,11 @@ func ParseExpr(x string) (ast.Expr, error) {
 
 	return e, nil
 }
+
+// ParseExpr is a convenience function for obtaining the AST of an expression x.
+// The position information recorded in the AST is undefined. The filename used
+// in error messages is the empty string.
+//
+func ParseExpr(x string) (ast.Expr, error) {
+	return ParseExprFrom(token.NewFileSet(), "", []byte(x), 0)
+}
diff --git a/libgo/go/go/parser/parser.go b/libgo/go/go/parser/parser.go
index 4a005d8ffa3..e82c0bd1223 100644
--- a/libgo/go/go/parser/parser.go
+++ b/libgo/go/go/parser/parser.go
@@ -7,6 +7,13 @@
 // output is an abstract syntax tree (AST) representing the Go source. The
 // parser is invoked through one of the Parse* functions.
 //
+// The parser accepts a larger language than is syntactically permitted by
+// the Go spec, for simplicity, and for improved robustness in the presence
+// of syntax errors. For instance, in method declarations, the receiver is
+// treated like an ordinary parameter list and thus may contain multiple
+// entries where the spec permits exactly one. Consequently, the corresponding
+// field in the AST (ast.FuncDecl.Recv) field is not restricted to one entry.
+//
 package parser
 
 import (
@@ -412,14 +419,17 @@ func (p *parser) expectSemi() {
 	}
 }
 
-func (p *parser) atComma(context string) bool {
+func (p *parser) atComma(context string, follow token.Token) bool {
 	if p.tok == token.COMMA {
 		return true
 	}
-	if p.tok == token.SEMICOLON && p.lit == "\n" {
-		p.error(p.pos, "missing ',' before newline in "+context)
-		return true // "insert" the comma and continue
-
+	if p.tok != follow {
+		msg := "missing ','"
+		if p.tok == token.SEMICOLON && p.lit == "\n" {
+			msg += " before newline"
+		}
+		p.error(p.pos, msg+" in "+context)
+		return true // "insert" comma and continue
 	}
 	return false
 }
@@ -825,7 +835,7 @@ func (p *parser) parseParameterList(scope *ast.Scope, ellipsisOk bool) (params [
 		// parameter or result variable is the function body.
 		p.declare(field, nil, scope, ast.Var, idents...)
 		p.resolve(typ)
-		if !p.atComma("parameter list") {
+		if !p.atComma("parameter list", token.RPAREN) {
 			return
 		}
 		p.next()
@@ -838,7 +848,7 @@ func (p *parser) parseParameterList(scope *ast.Scope, ellipsisOk bool) (params [
 			// parameter or result variable is the function body.
 			p.declare(field, nil, scope, ast.Var, idents...)
 			p.resolve(typ)
-			if !p.atComma("parameter list") {
+			if !p.atComma("parameter list", token.RPAREN) {
 				break
 			}
 			p.next()
@@ -1248,7 +1258,7 @@ func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
 			ellipsis = p.pos
 			p.next()
 		}
-		if !p.atComma("argument list") {
+		if !p.atComma("argument list", token.RPAREN) {
 			break
 		}
 		p.next()
@@ -1259,7 +1269,7 @@ func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
 	return &ast.CallExpr{Fun: fun, Lparen: lparen, Args: list, Ellipsis: ellipsis, Rparen: rparen}
 }
 
-func (p *parser) parseElement(keyOk bool) ast.Expr {
+func (p *parser) parseValue(keyOk bool) ast.Expr {
 	if p.trace {
 		defer un(trace(p, "Element"))
 	}
@@ -1287,16 +1297,30 @@ func (p *parser) parseElement(keyOk bool) ast.Expr {
 	x := p.checkExpr(p.parseExpr(keyOk))
 	if keyOk {
 		if p.tok == token.COLON {
-			colon := p.pos
-			p.next()
 			// Try to resolve the key but don't collect it
 			// as unresolved identifier if it fails so that
 			// we don't get (possibly false) errors about
 			// undeclared names.
 			p.tryResolve(x, false)
-			return &ast.KeyValueExpr{Key: x, Colon: colon, Value: p.parseElement(false)}
+		} else {
+			// not a key
+			p.resolve(x)
 		}
-		p.resolve(x) // not a key
+	}
+
+	return x
+}
+
+func (p *parser) parseElement() ast.Expr {
+	if p.trace {
+		defer un(trace(p, "Element"))
+	}
+
+	x := p.parseValue(true)
+	if p.tok == token.COLON {
+		colon := p.pos
+		p.next()
+		x = &ast.KeyValueExpr{Key: x, Colon: colon, Value: p.parseValue(false)}
 	}
 
 	return x
@@ -1308,8 +1332,8 @@ func (p *parser) parseElementList() (list []ast.Expr) {
 	}
 
 	for p.tok != token.RBRACE && p.tok != token.EOF {
-		list = append(list, p.parseElement(true))
-		if !p.atComma("composite literal") {
+		list = append(list, p.parseElement())
+		if !p.atComma("composite literal", token.RBRACE) {
 			break
 		}
 		p.next()
@@ -1365,7 +1389,7 @@ func (p *parser) checkExpr(x ast.Expr) ast.Expr {
 	return x
 }
 
-// isTypeName returns true iff x is a (qualified) TypeName.
+// isTypeName reports whether x is a (qualified) TypeName.
 func isTypeName(x ast.Expr) bool {
 	switch t := x.(type) {
 	case *ast.BadExpr:
@@ -1379,7 +1403,7 @@ func isTypeName(x ast.Expr) bool {
 	return true
 }
 
-// isLiteralType returns true iff x is a legal composite literal type.
+// isLiteralType reports whether x is a legal composite literal type.
 func isLiteralType(x ast.Expr) bool {
 	switch t := x.(type) {
 	case *ast.BadExpr:
@@ -1455,7 +1479,8 @@ L:
 				pos := p.pos
 				p.errorExpected(pos, "selector or type assertion")
 				p.next() // make progress
-				x = &ast.BadExpr{From: pos, To: p.pos}
+				sel := &ast.Ident{NamePos: pos, Name: "_"}
+				x = &ast.SelectorExpr{X: x, Sel: sel}
 			}
 		case token.LBRACK:
 			if lhs {
@@ -2123,7 +2148,7 @@ func (p *parser) parseStmt() (s ast.Stmt) {
 	case
 		// tokens that may start an expression
 		token.IDENT, token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING, token.FUNC, token.LPAREN, // operands
-		token.LBRACK, token.STRUCT, // composite types
+		token.LBRACK, token.STRUCT, token.MAP, token.CHAN, token.INTERFACE, // composite types
 		token.ADD, token.SUB, token.MUL, token.AND, token.XOR, token.ARROW, token.NOT: // unary operators
 		s, _ = p.parseSimpleStmt(labelOk)
 		// because of the required look-ahead, labeled statements are
@@ -2152,11 +2177,14 @@ func (p *parser) parseStmt() (s ast.Stmt) {
 	case token.FOR:
 		s = p.parseForStmt()
 	case token.SEMICOLON:
-		s = &ast.EmptyStmt{Semicolon: p.pos}
+		// Is it ever possible to have an implicit semicolon
+		// producing an empty statement in a valid program?
+		// (handle correctly anyway)
+		s = &ast.EmptyStmt{Semicolon: p.pos, Implicit: p.lit == "\n"}
 		p.next()
 	case token.RBRACE:
 		// a semicolon may be omitted before a closing "}"
-		s = &ast.EmptyStmt{Semicolon: p.pos}
+		s = &ast.EmptyStmt{Semicolon: p.pos, Implicit: true}
 	default:
 		// no statement found
 		pos := p.pos
@@ -2228,6 +2256,7 @@ func (p *parser) parseValueSpec(doc *ast.CommentGroup, keyword token.Token, iota
 		defer un(trace(p, keyword.String()+"Spec"))
 	}
 
+	pos := p.pos
 	idents := p.parseIdentList()
 	typ := p.tryType()
 	var values []ast.Expr
@@ -2238,6 +2267,17 @@ func (p *parser) parseValueSpec(doc *ast.CommentGroup, keyword token.Token, iota
 	}
 	p.expectSemi() // call before accessing p.linecomment
 
+	switch keyword {
+	case token.VAR:
+		if typ == nil && values == nil {
+			p.error(pos, "missing variable type or initialization")
+		}
+	case token.CONST:
+		if values == nil && (iota == 0 || typ != nil) {
+			p.error(pos, "missing constant value")
+		}
+	}
+
 	// Go spec: The scope of a constant or variable identifier declared inside
 	// a function begins at the end of the ConstSpec or VarSpec and ends at
 	// the end of the innermost containing block.
diff --git a/libgo/go/go/parser/parser_test.go b/libgo/go/go/parser/parser_test.go
index 85065fd1829..c7bb36d789d 100644
--- a/libgo/go/go/parser/parser_test.go
+++ b/libgo/go/go/parser/parser_test.go
@@ -14,8 +14,6 @@ import (
 	"testing"
 )
 
-var fset = token.NewFileSet()
-
 var validFiles = []string{
 	"parser.go",
 	"parser_test.go",
@@ -25,7 +23,7 @@ var validFiles = []string{
 
 func TestParse(t *testing.T) {
 	for _, filename := range validFiles {
-		_, err := ParseFile(fset, filename, nil, DeclarationErrors)
+		_, err := ParseFile(token.NewFileSet(), filename, nil, DeclarationErrors)
 		if err != nil {
 			t.Fatalf("ParseFile(%s): %v", filename, err)
 		}
@@ -46,7 +44,7 @@ func dirFilter(f os.FileInfo) bool { return nameFilter(f.Name()) }
 
 func TestParseDir(t *testing.T) {
 	path := "."
-	pkgs, err := ParseDir(fset, path, dirFilter, 0)
+	pkgs, err := ParseDir(token.NewFileSet(), path, dirFilter, 0)
 	if err != nil {
 		t.Fatalf("ParseDir(%s): %v", path, err)
 	}
@@ -131,7 +129,7 @@ func TestParseExpr(t *testing.T) {
 }
 
 func TestColonEqualsScope(t *testing.T) {
-	f, err := ParseFile(fset, "", `package p; func f() { x, y, z := x, y, z }`, 0)
+	f, err := ParseFile(token.NewFileSet(), "", `package p; func f() { x, y, z := x, y, z }`, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -153,7 +151,7 @@ func TestColonEqualsScope(t *testing.T) {
 }
 
 func TestVarScope(t *testing.T) {
-	f, err := ParseFile(fset, "", `package p; func f() { var x, y, z = x, y, z }`, 0)
+	f, err := ParseFile(token.NewFileSet(), "", `package p; func f() { var x, y, z = x, y, z }`, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -183,7 +181,7 @@ var x int
 func f() { L: }
 `
 
-	f, err := ParseFile(fset, "", src, 0)
+	f, err := ParseFile(token.NewFileSet(), "", src, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -221,7 +219,7 @@ func f() { L: }
 }
 
 func TestUnresolved(t *testing.T) {
-	f, err := ParseFile(fset, "", `
+	f, err := ParseFile(token.NewFileSet(), "", `
 package p
 //
 func f1a(int)
@@ -316,7 +314,7 @@ var imports = map[string]bool{
 func TestImports(t *testing.T) {
 	for path, isValid := range imports {
 		src := fmt.Sprintf("package p; import %s", path)
-		_, err := ParseFile(fset, "", src, 0)
+		_, err := ParseFile(token.NewFileSet(), "", src, 0)
 		switch {
 		case err != nil && isValid:
 			t.Errorf("ParseFile(%s): got %v; expected no error", src, err)
@@ -327,7 +325,7 @@ func TestImports(t *testing.T) {
 }
 
 func TestCommentGroups(t *testing.T) {
-	f, err := ParseFile(fset, "", `
+	f, err := ParseFile(token.NewFileSet(), "", `
 package p /* 1a */ /* 1b */      /* 1c */ // 1d
 /* 2a
 */
@@ -421,7 +419,7 @@ func checkFieldComments(t *testing.T, file *ast.File, fieldname, lead, line stri
 }
 
 func TestLeadAndLineComments(t *testing.T) {
-	f, err := ParseFile(fset, "", `
+	f, err := ParseFile(token.NewFileSet(), "", `
 package p
 type T struct {
 	/* F1 lead comment */
@@ -447,3 +445,89 @@ type T struct {
 		t.Error("not expected to find T.f3")
 	}
 }
+
+// TestIssue9979 verifies that empty statements are contained within their enclosing blocks.
+func TestIssue9979(t *testing.T) {
+	for _, src := range []string{
+		"package p; func f() {;}",
+		"package p; func f() {L:}",
+		"package p; func f() {L:;}",
+		"package p; func f() {L:\n}",
+		"package p; func f() {L:\n;}",
+		"package p; func f() { ; }",
+		"package p; func f() { L: }",
+		"package p; func f() { L: ; }",
+		"package p; func f() { L: \n}",
+		"package p; func f() { L: \n; }",
+	} {
+		fset := token.NewFileSet()
+		f, err := ParseFile(fset, "", src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		var pos, end token.Pos
+		ast.Inspect(f, func(x ast.Node) bool {
+			switch s := x.(type) {
+			case *ast.BlockStmt:
+				pos, end = s.Pos()+1, s.End()-1 // exclude "{", "}"
+			case *ast.LabeledStmt:
+				pos, end = s.Pos()+2, s.End() // exclude "L:"
+			case *ast.EmptyStmt:
+				// check containment
+				if s.Pos() < pos || s.End() > end {
+					t.Errorf("%s: %T[%d, %d] not inside [%d, %d]", src, s, s.Pos(), s.End(), pos, end)
+				}
+				// check semicolon
+				offs := fset.Position(s.Pos()).Offset
+				if ch := src[offs]; ch != ';' != s.Implicit {
+					want := "want ';'"
+					if s.Implicit {
+						want = "but ';' is implicit"
+					}
+					t.Errorf("%s: found %q at offset %d; %s", src, ch, offs, want)
+				}
+			}
+			return true
+		})
+	}
+}
+
+// TestIncompleteSelection ensures that an incomplete selector
+// expression is parsed as a (blank) *ast.SelectorExpr, not a
+// *ast.BadExpr.
+func TestIncompleteSelection(t *testing.T) {
+	for _, src := range []string{
+		"package p; var _ = fmt.",             // at EOF
+		"package p; var _ = fmt.\ntype X int", // not at EOF
+	} {
+		fset := token.NewFileSet()
+		f, err := ParseFile(fset, "", src, 0)
+		if err == nil {
+			t.Errorf("ParseFile(%s) succeeded unexpectedly", src)
+			continue
+		}
+
+		const wantErr = "expected selector or type assertion"
+		if !strings.Contains(err.Error(), wantErr) {
+			t.Errorf("ParseFile returned wrong error %q, want %q", err, wantErr)
+		}
+
+		var sel *ast.SelectorExpr
+		ast.Inspect(f, func(n ast.Node) bool {
+			if n, ok := n.(*ast.SelectorExpr); ok {
+				sel = n
+			}
+			return true
+		})
+		if sel == nil {
+			t.Error("found no *ast.SelectorExpr")
+			continue
+		}
+		const wantSel = "&{fmt _}"
+		if fmt.Sprint(sel) != wantSel {
+			t.Errorf("found selector %s, want %s", sel, wantSel)
+			continue
+		}
+	}
+}
diff --git a/libgo/go/go/parser/short_test.go b/libgo/go/go/parser/short_test.go
index 05e44de28a7..ef2ffadbd98 100644
--- a/libgo/go/go/parser/short_test.go
+++ b/libgo/go/go/parser/short_test.go
@@ -40,6 +40,12 @@ var valids = []string{
 	`package p; func (*(T),) m() {}`,
 	`package p; func _(x []int) { for range x {} }`,
 	`package p; func _() { if [T{}.n]int{} {} }`,
+	`package p; func _() { map[int]int{}[0]++; map[int]int{}[0] += 1 }`,
+	`package p; func _(x interface{f()}) { interface{f()}(x).f() }`,
+	`package p; func _(x chan int) { chan int(x) <- 0 }`,
+	`package p; const (x = 0; y; z)`, // issue 9639
+	`package p; var _ = map[P]int{P{}:0, {}:1}`,
+	`package p; var _ = map[*P]int{&P{}:0, {}:1}`,
 }
 
 func TestValid(t *testing.T) {
@@ -93,8 +99,13 @@ var invalids = []string{
 	`package p; func f() { for i /* ERROR "boolean or range expression" */ , x := []string {} }`,
 	`package p; func f() { go f /* ERROR HERE "function must be invoked" */ }`,
 	`package p; func f() { defer func() {} /* ERROR HERE "function must be invoked" */ }`,
-	`package p; func f() { go func() { func() { f(x func /* ERROR "expected '\)'" */ (){}) } } }`,
-	`package p; func f() (a b string /* ERROR "expected '\)'" */ , ok bool) // issue 8656`,
+	`package p; func f() { go func() { func() { f(x func /* ERROR "missing ','" */ (){}) } } }`,
+	`package p; func f(x func(), u v func /* ERROR "missing ','" */ ()){}`,
+	`package p; func f() (a b string /* ERROR "missing ','" */ , ok bool)`,           // issue 8656
+	`package p; var x /* ERROR "missing variable type or initialization" */ , y, z;`, // issue 9639
+	`package p; const x /* ERROR "missing constant value" */ ;`,                      // issue 9639
+	`package p; const x /* ERROR "missing constant value" */ int;`,                   // issue 9639
+	`package p; const (x = 0; y; z /* ERROR "missing constant value" */ int);`,       // issue 9639
 }
 
 func TestInvalid(t *testing.T) {
diff --git a/libgo/go/go/parser/testdata/issue3106.src b/libgo/go/go/parser/testdata/issue3106.src
index 82796c8ceb6..2db10be2354 100644
--- a/libgo/go/go/parser/testdata/issue3106.src
+++ b/libgo/go/go/parser/testdata/issue3106.src
@@ -19,7 +19,7 @@ func f() {
 				time.Sleep(1e8)
 				m.Lock()
 				defer
-				if /* ERROR "expected operand, found 'if'" */ percent == 100 {
+				if /* ERROR "expected ';', found 'if'" */ percent == 100 {
 					m.Unlock()
 					break
 				}
diff --git a/libgo/go/go/printer/nodes.go b/libgo/go/go/printer/nodes.go
index d5a69349beb..fe047053afb 100644
--- a/libgo/go/go/printer/nodes.go
+++ b/libgo/go/go/printer/nodes.go
@@ -12,6 +12,9 @@ import (
 	"bytes"
 	"go/ast"
 	"go/token"
+	"strconv"
+	"strings"
+	"unicode"
 	"unicode/utf8"
 )
 
@@ -1334,6 +1337,49 @@ func (p *printer) valueSpec(s *ast.ValueSpec, keepType bool) {
 	}
 }
 
+func sanitizeImportPath(lit *ast.BasicLit) *ast.BasicLit {
+	// Note: An unmodified AST generated by go/parser will already
+	// contain a backward- or double-quoted path string that does
+	// not contain any invalid characters, and most of the work
+	// here is not needed. However, a modified or generated AST
+	// may possibly contain non-canonical paths. Do the work in
+	// all cases since it's not too hard and not speed-critical.
+
+	// if we don't have a proper string, be conservative and return whatever we have
+	if lit.Kind != token.STRING {
+		return lit
+	}
+	s, err := strconv.Unquote(lit.Value)
+	if err != nil {
+		return lit
+	}
+
+	// if the string is an invalid path, return whatever we have
+	//
+	// spec: "Implementation restriction: A compiler may restrict
+	// ImportPaths to non-empty strings using only characters belonging
+	// to Unicode's L, M, N, P, and S general categories (the Graphic
+	// characters without spaces) and may also exclude the characters
+	// !"#$%&'()*,:;<=>?[\]^`{|} and the Unicode replacement character
+	// U+FFFD."
+	if s == "" {
+		return lit
+	}
+	const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
+	for _, r := range s {
+		if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
+			return lit
+		}
+	}
+
+	// otherwise, return the double-quoted path
+	s = strconv.Quote(s)
+	if s == lit.Value {
+		return lit // nothing wrong with lit
+	}
+	return &ast.BasicLit{ValuePos: lit.ValuePos, Kind: token.STRING, Value: s}
+}
+
 // The parameter n is the number of specs in the group. If doIndent is set,
 // multi-line identifier lists in the spec are indented when the first
 // linebreak is encountered.
@@ -1346,7 +1392,7 @@ func (p *printer) spec(spec ast.Spec, n int, doIndent bool) {
 			p.expr(s.Name)
 			p.print(blank)
 		}
-		p.expr(s.Path)
+		p.expr(sanitizeImportPath(s.Path))
 		p.setComment(s.Comment)
 		p.print(s.EndPos)
 
diff --git a/libgo/go/go/printer/printer.go b/libgo/go/go/printer/printer.go
index 280c697a0dd..f9343d3af0d 100644
--- a/libgo/go/go/printer/printer.go
+++ b/libgo/go/go/printer/printer.go
@@ -144,7 +144,7 @@ func (p *printer) nextComment() {
 	p.commentOffset = infinity
 }
 
-// commentBefore returns true iff the current comment group occurs
+// commentBefore reports whether the current comment group occurs
 // before the next position in the source code and printing it does
 // not introduce implicit semicolons.
 //
@@ -496,29 +496,33 @@ func stripCommonPrefix(lines []string) {
 	// Compute maximum common white prefix of all but the first,
 	// last, and blank lines, and replace blank lines with empty
 	// lines (the first line starts with /* and has no prefix).
-	// In case of two-line comments, consider the last line for
-	// the prefix computation since otherwise the prefix would
-	// be empty.
+	// In cases where only the first and last lines are not blank,
+	// such as two-line comments, or comments where all inner lines
+	// are blank, consider the last line for the prefix computation
+	// since otherwise the prefix would be empty.
 	//
 	// Note that the first and last line are never empty (they
 	// contain the opening /* and closing */ respectively) and
 	// thus they can be ignored by the blank line check.
-	var prefix string
+	prefix := ""
+	prefixSet := false
 	if len(lines) > 2 {
-		first := true
 		for i, line := range lines[1 : len(lines)-1] {
-			switch {
-			case isBlank(line):
+			if isBlank(line) {
 				lines[1+i] = "" // range starts with lines[1]
-			case first:
-				prefix = commonPrefix(line, line)
-				first = false
-			default:
+			} else {
+				if !prefixSet {
+					prefix = line
+					prefixSet = true
+				}
 				prefix = commonPrefix(prefix, line)
 			}
+
 		}
-	} else { // len(lines) == 2, lines cannot be blank (contain /* and */)
-		line := lines[1]
+	}
+	// If we don't have a prefix yet, consider the last line.
+	if !prefixSet {
+		line := lines[len(lines)-1]
 		prefix = commonPrefix(line, line)
 	}
 
diff --git a/libgo/go/go/printer/testdata/comments.golden b/libgo/go/go/printer/testdata/comments.golden
index b1af7958a96..849fa624489 100644
--- a/libgo/go/go/printer/testdata/comments.golden
+++ b/libgo/go/go/printer/testdata/comments.golden
@@ -413,6 +413,68 @@ func _() {
 		aligned line */
 }
 
+// Issue 9751.
+func _() {
+	/*a string
+
+	b string*/
+
+	/*A string
+
+
+
+	Z string*/
+
+	/*a string
+
+	b string
+
+	c string*/
+
+	{
+		/*a string
+		b string*/
+
+		/*a string
+
+		b string*/
+
+		/*a string
+
+		b string
+
+		c string*/
+	}
+
+	{
+		/*a string
+		b string*/
+
+		/*a string
+
+		b string*/
+
+		/*a string
+
+		b string
+
+		c string*/
+	}
+
+	/*
+	 */
+
+	/*
+
+	 */
+
+	/*
+
+	 * line
+
+	 */
+}
+
 /*
  * line
  * of
diff --git a/libgo/go/go/printer/testdata/comments.input b/libgo/go/go/printer/testdata/comments.input
index 983e2b2c97e..30cd23c6dd4 100644
--- a/libgo/go/go/printer/testdata/comments.input
+++ b/libgo/go/go/printer/testdata/comments.input
@@ -418,6 +418,68 @@ func _() {
 		aligned line */
 }
 
+// Issue 9751.
+func _() {
+	/*a string
+
+	b string*/
+
+	/*A string
+
+
+
+	Z string*/
+
+	/*a string
+
+	b string
+
+	c string*/
+
+	{
+		/*a string
+b string*/
+
+		/*a string
+
+b string*/
+
+		/*a string
+
+b string
+
+c string*/
+	}
+
+	{
+		/*a string
+				b string*/
+
+		/*a string
+
+				b string*/
+
+		/*a string
+
+				b string
+
+				c string*/
+	}
+
+	/*
+	*/
+
+	/*
+
+	*/
+
+	/*
+
+	 * line
+
+	*/
+}
+
 /*
  * line
  * of
diff --git a/libgo/go/go/printer/testdata/declarations.golden b/libgo/go/go/printer/testdata/declarations.golden
index 9acd41b7d28..82f5e0f9147 100644
--- a/libgo/go/go/printer/testdata/declarations.golden
+++ b/libgo/go/go/printer/testdata/declarations.golden
@@ -110,6 +110,15 @@ import (
 	"package_dddd"	// comment
 )
 
+// print import paths as double-quoted strings
+// (we would like more test cases but the go/parser
+// already excludes most incorrect paths, and we don't
+// bother setting up test-ASTs manually)
+import (
+	"fmt"
+	"math"
+)
+
 // at least one empty line between declarations of different kind
 import _ "io"
 
diff --git a/libgo/go/go/printer/testdata/declarations.input b/libgo/go/go/printer/testdata/declarations.input
index 45beec25fc7..a0a3783b846 100644
--- a/libgo/go/go/printer/testdata/declarations.input
+++ b/libgo/go/go/printer/testdata/declarations.input
@@ -111,6 +111,15 @@ import (
 	"package_dddd" // comment
 )
 
+// print import paths as double-quoted strings
+// (we would like more test cases but the go/parser
+// already excludes most incorrect paths, and we don't
+// bother setting up test-ASTs manually)
+import (
+	`fmt`
+	"math"
+)
+
 // at least one empty line between declarations of different kind
 import _ "io"
 var _ int
diff --git a/libgo/go/go/printer/testdata/parser.go b/libgo/go/go/printer/testdata/parser.go
index dba8bbd4351..44dfa19ff35 100644
--- a/libgo/go/go/printer/testdata/parser.go
+++ b/libgo/go/go/printer/testdata/parser.go
@@ -1165,7 +1165,7 @@ func (p *parser) checkExpr(x ast.Expr) ast.Expr {
 	return x
 }
 
-// isTypeName returns true iff x is a (qualified) TypeName.
+// isTypeName reports whether x is a (qualified) TypeName.
 func isTypeName(x ast.Expr) bool {
 	switch t := x.(type) {
 	case *ast.BadExpr:
@@ -1179,7 +1179,7 @@ func isTypeName(x ast.Expr) bool {
 	return true
 }
 
-// isLiteralType returns true iff x is a legal composite literal type.
+// isLiteralType reports whether x is a legal composite literal type.
 func isLiteralType(x ast.Expr) bool {
 	switch t := x.(type) {
 	case *ast.BadExpr:
diff --git a/libgo/go/go/scanner/errors.go b/libgo/go/go/scanner/errors.go
index 22de69c3c1c..bf7bfa30e4b 100644
--- a/libgo/go/go/scanner/errors.go
+++ b/libgo/go/go/scanner/errors.go
@@ -54,18 +54,16 @@ func (p ErrorList) Less(i, j int) bool {
 	// Note that it is not sufficient to simply compare file offsets because
 	// the offsets do not reflect modified line information (through //line
 	// comments).
-	if e.Filename < f.Filename {
-		return true
+	if e.Filename != f.Filename {
+		return e.Filename < f.Filename
 	}
-	if e.Filename == f.Filename {
-		if e.Line < f.Line {
-			return true
-		}
-		if e.Line == f.Line {
-			return e.Column < f.Column
-		}
+	if e.Line != f.Line {
+		return e.Line < f.Line
+	}
+	if e.Column != f.Column {
+		return e.Column < f.Column
 	}
-	return false
+	return p[i].Msg < p[j].Msg
 }
 
 // Sort sorts an ErrorList. *Error entries are sorted by position,
diff --git a/libgo/go/go/scanner/scanner.go b/libgo/go/go/scanner/scanner.go
index cec82ea10ef..e9476c4dee4 100644
--- a/libgo/go/go/scanner/scanner.go
+++ b/libgo/go/go/scanner/scanner.go
@@ -706,13 +706,14 @@ scanAgain:
 					s.insertSemi = false // newline consumed
 					return pos, token.SEMICOLON, "\n"
 				}
-				lit = s.scanComment()
+				comment := s.scanComment()
 				if s.mode&ScanComments == 0 {
 					// skip comment
 					s.insertSemi = false // newline consumed
 					goto scanAgain
 				}
 				tok = token.COMMENT
+				lit = comment
 			} else {
 				tok = s.switch2(token.QUO, token.QUO_ASSIGN)
 			}
diff --git a/libgo/go/go/scanner/scanner_test.go b/libgo/go/go/scanner/scanner_test.go
index fc450d8a6eb..0d21905166c 100644
--- a/libgo/go/go/scanner/scanner_test.go
+++ b/libgo/go/go/scanner/scanner_test.go
@@ -734,6 +734,41 @@ func TestScanErrors(t *testing.T) {
 	}
 }
 
+// Verify that no comments show up as literal values when skipping comments.
+func TestIssue10213(t *testing.T) {
+	var src = `
+		var (
+			A = 1 // foo
+		)
+
+		var (
+			B = 2
+			// foo
+		)
+
+		var C = 3 // foo
+
+		var D = 4
+		// foo
+
+		func anycode() {
+		// foo
+		}
+	`
+	var s Scanner
+	s.Init(fset.AddFile("", fset.Base(), len(src)), []byte(src), nil, 0)
+	for {
+		pos, tok, lit := s.Scan()
+		class := tokenclass(tok)
+		if lit != "" && class != keyword && class != literal && tok != token.SEMICOLON {
+			t.Errorf("%s: tok = %s, lit = %q", fset.Position(pos), tok, lit)
+		}
+		if tok <= token.EOF {
+			break
+		}
+	}
+}
+
 func BenchmarkScan(b *testing.B) {
 	b.StopTimer()
 	fset := token.NewFileSet()
diff --git a/libgo/go/go/token/position.go b/libgo/go/go/token/position.go
index 82d90eeb728..33751779a3d 100644
--- a/libgo/go/go/token/position.go
+++ b/libgo/go/go/token/position.go
@@ -21,10 +21,10 @@ type Position struct {
 	Filename string // filename, if any
 	Offset   int    // offset, starting at 0
 	Line     int    // line number, starting at 1
-	Column   int    // column number, starting at 1 (character count)
+	Column   int    // column number, starting at 1 (byte count)
 }
 
-// IsValid returns true if the position is valid.
+// IsValid reports whether the position is valid.
 func (pos *Position) IsValid() bool { return pos.Line > 0 }
 
 // String returns a string in one of several forms:
@@ -56,8 +56,8 @@ func (pos Position) String() string {
 // where base and size are specified when adding the file to the file set via
 // AddFile.
 //
-// To create the Pos value for a specific source offset, first add
-// the respective file to the current file set (via FileSet.AddFile)
+// To create the Pos value for a specific source offset (measured in bytes),
+// first add the respective file to the current file set using FileSet.AddFile
 // and then call File.Pos(offset) for that file. Given a Pos value p
 // for a specific file set fset, the corresponding Position value is
 // obtained by calling fset.Position(p).
@@ -77,7 +77,7 @@ type Pos int
 //
 const NoPos Pos = 0
 
-// IsValid returns true if the position is valid.
+// IsValid reports whether the position is valid.
 func (p Pos) IsValid() bool {
 	return p != NoPos
 }
@@ -157,7 +157,7 @@ func (f *File) MergeLine(line int) {
 	f.lines = f.lines[:len(f.lines)-1]
 }
 
-// SetLines sets the line offsets for a file and returns true if successful.
+// SetLines sets the line offsets for a file and reports whether it succeeded.
 // The line offsets are the offsets of the first character of each line;
 // for instance for the content "ab\nc\n" the line offsets are {0, 3}.
 // An empty file has an empty line offset table.
diff --git a/libgo/go/go/types/api.go b/libgo/go/go/types/api.go
new file mode 100644
index 00000000000..b3bf6f01476
--- /dev/null
+++ b/libgo/go/go/types/api.go
@@ -0,0 +1,336 @@
+// 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 types declares the data types and implements
+// the algorithms for type-checking of Go packages. Use
+// Config.Check to invoke the type checker for a package.
+// Alternatively, create a new type checked with NewChecker
+// and invoke it incrementally by calling Checker.Files.
+//
+// Type-checking consists of several interdependent phases:
+//
+// Name resolution maps each identifier (ast.Ident) in the program to the
+// language object (Object) it denotes.
+// Use Info.{Defs,Uses,Implicits} for the results of name resolution.
+//
+// Constant folding computes the exact constant value (constant.Value)
+// for every expression (ast.Expr) that is a compile-time constant.
+// Use Info.Types[expr].Value for the results of constant folding.
+//
+// Type inference computes the type (Type) of every expression (ast.Expr)
+// and checks for compliance with the language specification.
+// Use Info.Types[expr].Type for the results of type inference.
+//
+package types // import "go/types"
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+// An Error describes a type-checking error; it implements the error interface.
+// A "soft" error is an error that still permits a valid interpretation of a
+// package (such as "unused variable"); "hard" errors may lead to unpredictable
+// behavior if ignored.
+type Error struct {
+	Fset *token.FileSet // file set for interpretation of Pos
+	Pos  token.Pos      // error position
+	Msg  string         // error message
+	Soft bool           // if set, error is "soft"
+}
+
+// Error returns an error string formatted as follows:
+// filename:line:column: message
+func (err Error) Error() string {
+	return fmt.Sprintf("%s: %s", err.Fset.Position(err.Pos), err.Msg)
+}
+
+// An importer resolves import paths to Packages.
+// See go/importer for existing implementations.
+type Importer interface {
+	// Import returns the imported package for the given import
+	// path, or an error if the package couldn't be imported.
+	// Import is responsible for returning the same package for
+	// matching import paths.
+	Import(path string) (*Package, error)
+}
+
+// A Config specifies the configuration for type checking.
+// The zero value for Config is a ready-to-use default configuration.
+type Config struct {
+	// If IgnoreFuncBodies is set, function bodies are not
+	// type-checked.
+	IgnoreFuncBodies bool
+
+	// If FakeImportC is set, `import "C"` (for packages requiring Cgo)
+	// declares an empty "C" package and errors are omitted for qualified
+	// identifiers referring to package C (which won't find an object).
+	// This feature is intended for the standard library cmd/api tool.
+	//
+	// Caution: Effects may be unpredictable due to follow-up errors.
+	//          Do not use casually!
+	FakeImportC bool
+
+	// If Error != nil, it is called with each error found
+	// during type checking; err has dynamic type Error.
+	// Secondary errors (for instance, to enumerate all types
+	// involved in an invalid recursive type declaration) have
+	// error strings that start with a '\t' character.
+	// If Error == nil, type-checking stops with the first
+	// error found.
+	Error func(err error)
+
+	// Importer is called for each import declaration except when
+	// importing package "unsafe". An error is reported if an
+	// importer is needed but none was installed.
+	Importer Importer
+
+	// If Sizes != nil, it provides the sizing functions for package unsafe.
+	// Otherwise &StdSizes{WordSize: 8, MaxAlign: 8} is used instead.
+	Sizes Sizes
+
+	// If DisableUnusedImportCheck is set, packages are not checked
+	// for unused imports.
+	DisableUnusedImportCheck bool
+}
+
+// Info holds result type information for a type-checked package.
+// Only the information for which a map is provided is collected.
+// If the package has type errors, the collected information may
+// be incomplete.
+type Info struct {
+	// Types maps expressions to their types, and for constant
+	// expressions, their values. Invalid expressions are omitted.
+	//
+	// For (possibly parenthesized) identifiers denoting built-in
+	// functions, the recorded signatures are call-site specific:
+	// if the call result is not a constant, the recorded type is
+	// an argument-specific signature. Otherwise, the recorded type
+	// is invalid.
+	//
+	// Identifiers on the lhs of declarations (i.e., the identifiers
+	// which are being declared) are collected in the Defs map.
+	// Identifiers denoting packages are collected in the Uses maps.
+	Types map[ast.Expr]TypeAndValue
+
+	// Defs maps identifiers to the objects they define (including
+	// package names, dots "." of dot-imports, and blank "_" identifiers).
+	// For identifiers that do not denote objects (e.g., the package name
+	// in package clauses, or symbolic variables t in t := x.(type) of
+	// type switch headers), the corresponding objects are nil.
+	//
+	// For an anonymous field, Defs returns the field *Var it defines.
+	//
+	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
+	Defs map[*ast.Ident]Object
+
+	// Uses maps identifiers to the objects they denote.
+	//
+	// For an anonymous field, Uses returns the *TypeName it denotes.
+	//
+	// Invariant: Uses[id].Pos() != id.Pos()
+	Uses map[*ast.Ident]Object
+
+	// Implicits maps nodes to their implicitly declared objects, if any.
+	// The following node and object types may appear:
+	//
+	//	node               declared object
+	//
+	//	*ast.ImportSpec    *PkgName for dot-imports and imports without renames
+	//	*ast.CaseClause    type-specific *Var for each type switch case clause (incl. default)
+	//      *ast.Field         anonymous struct field or parameter *Var
+	//
+	Implicits map[ast.Node]Object
+
+	// Selections maps selector expressions (excluding qualified identifiers)
+	// to their corresponding selections.
+	Selections map[*ast.SelectorExpr]*Selection
+
+	// Scopes maps ast.Nodes to the scopes they define. Package scopes are not
+	// associated with a specific node but with all files belonging to a package.
+	// Thus, the package scope can be found in the type-checked Package object.
+	// Scopes nest, with the Universe scope being the outermost scope, enclosing
+	// the package scope, which contains (one or more) files scopes, which enclose
+	// function scopes which in turn enclose statement and function literal scopes.
+	// Note that even though package-level functions are declared in the package
+	// scope, the function scopes are embedded in the file scope of the file
+	// containing the function declaration.
+	//
+	// The following node types may appear in Scopes:
+	//
+	//	*ast.File
+	//	*ast.FuncType
+	//	*ast.BlockStmt
+	//	*ast.IfStmt
+	//	*ast.SwitchStmt
+	//	*ast.TypeSwitchStmt
+	//	*ast.CaseClause
+	//	*ast.CommClause
+	//	*ast.ForStmt
+	//	*ast.RangeStmt
+	//
+	Scopes map[ast.Node]*Scope
+
+	// InitOrder is the list of package-level initializers in the order in which
+	// they must be executed. Initializers referring to variables related by an
+	// initialization dependency appear in topological order, the others appear
+	// in source order. Variables without an initialization expression do not
+	// appear in this list.
+	InitOrder []*Initializer
+}
+
+// TypeOf returns the type of expression e, or nil if not found.
+// Precondition: the Types, Uses and Defs maps are populated.
+//
+func (info *Info) TypeOf(e ast.Expr) Type {
+	if t, ok := info.Types[e]; ok {
+		return t.Type
+	}
+	if id, _ := e.(*ast.Ident); id != nil {
+		if obj := info.ObjectOf(id); obj != nil {
+			return obj.Type()
+		}
+	}
+	return nil
+}
+
+// ObjectOf returns the object denoted by the specified id,
+// or nil if not found.
+//
+// If id is an anonymous struct field, ObjectOf returns the field (*Var)
+// it uses, not the type (*TypeName) it defines.
+//
+// Precondition: the Uses and Defs maps are populated.
+//
+func (info *Info) ObjectOf(id *ast.Ident) Object {
+	if obj, _ := info.Defs[id]; obj != nil {
+		return obj
+	}
+	return info.Uses[id]
+}
+
+// TypeAndValue reports the type and value (for constants)
+// of the corresponding expression.
+type TypeAndValue struct {
+	mode  operandMode
+	Type  Type
+	Value constant.Value
+}
+
+// TODO(gri) Consider eliminating the IsVoid predicate. Instead, report
+// "void" values as regular values but with the empty tuple type.
+
+// IsVoid reports whether the corresponding expression
+// is a function call without results.
+func (tv TypeAndValue) IsVoid() bool {
+	return tv.mode == novalue
+}
+
+// IsType reports whether the corresponding expression specifies a type.
+func (tv TypeAndValue) IsType() bool {
+	return tv.mode == typexpr
+}
+
+// IsBuiltin reports whether the corresponding expression denotes
+// a (possibly parenthesized) built-in function.
+func (tv TypeAndValue) IsBuiltin() bool {
+	return tv.mode == builtin
+}
+
+// IsValue reports whether the corresponding expression is a value.
+// Builtins are not considered values. Constant values have a non-
+// nil Value.
+func (tv TypeAndValue) IsValue() bool {
+	switch tv.mode {
+	case constant_, variable, mapindex, value, commaok:
+		return true
+	}
+	return false
+}
+
+// IsNil reports whether the corresponding expression denotes the
+// predeclared value nil.
+func (tv TypeAndValue) IsNil() bool {
+	return tv.mode == value && tv.Type == Typ[UntypedNil]
+}
+
+// Addressable reports whether the corresponding expression
+// is addressable (https://golang.org/ref/spec#Address_operators).
+func (tv TypeAndValue) Addressable() bool {
+	return tv.mode == variable
+}
+
+// Assignable reports whether the corresponding expression
+// is assignable to (provided a value of the right type).
+func (tv TypeAndValue) Assignable() bool {
+	return tv.mode == variable || tv.mode == mapindex
+}
+
+// HasOk reports whether the corresponding expression may be
+// used on the lhs of a comma-ok assignment.
+func (tv TypeAndValue) HasOk() bool {
+	return tv.mode == commaok || tv.mode == mapindex
+}
+
+// An Initializer describes a package-level variable, or a list of variables in case
+// of a multi-valued initialization expression, and the corresponding initialization
+// expression.
+type Initializer struct {
+	Lhs []*Var // var Lhs = Rhs
+	Rhs ast.Expr
+}
+
+func (init *Initializer) String() string {
+	var buf bytes.Buffer
+	for i, lhs := range init.Lhs {
+		if i > 0 {
+			buf.WriteString(", ")
+		}
+		buf.WriteString(lhs.Name())
+	}
+	buf.WriteString(" = ")
+	WriteExpr(&buf, init.Rhs)
+	return buf.String()
+}
+
+// Check type-checks a package and returns the resulting package object,
+// the first error if any, and if info != nil, additional type information.
+// The package is marked as complete if no errors occurred, otherwise it is
+// incomplete. See Config.Error for controlling behavior in the presence of
+// errors.
+//
+// The package is specified by a list of *ast.Files and corresponding
+// file set, and the package path the package is identified with.
+// The clean path must not be empty or dot (".").
+func (conf *Config) Check(path string, fset *token.FileSet, files []*ast.File, info *Info) (*Package, error) {
+	pkg := NewPackage(path, "")
+	return pkg, NewChecker(conf, fset, pkg, info).Files(files)
+}
+
+// AssertableTo reports whether a value of type V can be asserted to have type T.
+func AssertableTo(V *Interface, T Type) bool {
+	m, _ := assertableTo(V, T)
+	return m == nil
+}
+
+// AssignableTo reports whether a value of type V is assignable to a variable of type T.
+func AssignableTo(V, T Type) bool {
+	x := operand{mode: value, typ: V}
+	return x.assignableTo(nil, T) // config not needed for non-constant x
+}
+
+// ConvertibleTo reports whether a value of type V is convertible to a value of type T.
+func ConvertibleTo(V, T Type) bool {
+	x := operand{mode: value, typ: V}
+	return x.convertibleTo(nil, T) // config not needed for non-constant x
+}
+
+// Implements reports whether type V implements interface T.
+func Implements(V Type, T *Interface) bool {
+	f, _ := MissingMethod(V, T, true)
+	return f == nil
+}
diff --git a/libgo/go/go/types/api_test.go b/libgo/go/go/types/api_test.go
new file mode 100644
index 00000000000..eeda0d847c3
--- /dev/null
+++ b/libgo/go/go/types/api_test.go
@@ -0,0 +1,1044 @@
+// Copyright 2013 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 types_test
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"internal/testenv"
+	"reflect"
+	"regexp"
+	"strings"
+	"testing"
+
+	. "go/types"
+)
+
+func pkgFor(path, source string, info *Info) (*Package, error) {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, path, source, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	conf := Config{Importer: importer.Default()}
+	return conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
+}
+
+func mustTypecheck(t *testing.T, path, source string, info *Info) string {
+	pkg, err := pkgFor(path, source, info)
+	if err != nil {
+		name := path
+		if pkg != nil {
+			name = "package " + pkg.Name()
+		}
+		t.Fatalf("%s: didn't type-check (%s)", name, err)
+	}
+	return pkg.Name()
+}
+
+func TestValuesInfo(t *testing.T) {
+	var tests = []struct {
+		src  string
+		expr string // constant expression
+		typ  string // constant type
+		val  string // constant value
+	}{
+		{`package a0; const _ = false`, `false`, `untyped bool`, `false`},
+		{`package a1; const _ = 0`, `0`, `untyped int`, `0`},
+		{`package a2; const _ = 'A'`, `'A'`, `untyped rune`, `65`},
+		{`package a3; const _ = 0.`, `0.`, `untyped float`, `0`},
+		{`package a4; const _ = 0i`, `0i`, `untyped complex`, `0`},
+		{`package a5; const _ = "foo"`, `"foo"`, `untyped string`, `"foo"`},
+
+		{`package b0; var _ = false`, `false`, `bool`, `false`},
+		{`package b1; var _ = 0`, `0`, `int`, `0`},
+		{`package b2; var _ = 'A'`, `'A'`, `rune`, `65`},
+		{`package b3; var _ = 0.`, `0.`, `float64`, `0`},
+		{`package b4; var _ = 0i`, `0i`, `complex128`, `0`},
+		{`package b5; var _ = "foo"`, `"foo"`, `string`, `"foo"`},
+
+		{`package c0a; var _ = bool(false)`, `false`, `bool`, `false`},
+		{`package c0b; var _ = bool(false)`, `bool(false)`, `bool`, `false`},
+		{`package c0c; type T bool; var _ = T(false)`, `T(false)`, `c0c.T`, `false`},
+
+		{`package c1a; var _ = int(0)`, `0`, `int`, `0`},
+		{`package c1b; var _ = int(0)`, `int(0)`, `int`, `0`},
+		{`package c1c; type T int; var _ = T(0)`, `T(0)`, `c1c.T`, `0`},
+
+		{`package c2a; var _ = rune('A')`, `'A'`, `rune`, `65`},
+		{`package c2b; var _ = rune('A')`, `rune('A')`, `rune`, `65`},
+		{`package c2c; type T rune; var _ = T('A')`, `T('A')`, `c2c.T`, `65`},
+
+		{`package c3a; var _ = float32(0.)`, `0.`, `float32`, `0`},
+		{`package c3b; var _ = float32(0.)`, `float32(0.)`, `float32`, `0`},
+		{`package c3c; type T float32; var _ = T(0.)`, `T(0.)`, `c3c.T`, `0`},
+
+		{`package c4a; var _ = complex64(0i)`, `0i`, `complex64`, `0`},
+		{`package c4b; var _ = complex64(0i)`, `complex64(0i)`, `complex64`, `0`},
+		{`package c4c; type T complex64; var _ = T(0i)`, `T(0i)`, `c4c.T`, `0`},
+
+		{`package c5a; var _ = string("foo")`, `"foo"`, `string`, `"foo"`},
+		{`package c5b; var _ = string("foo")`, `string("foo")`, `string`, `"foo"`},
+		{`package c5c; type T string; var _ = T("foo")`, `T("foo")`, `c5c.T`, `"foo"`},
+
+		{`package d0; var _ = []byte("foo")`, `"foo"`, `string`, `"foo"`},
+		{`package d1; var _ = []byte(string("foo"))`, `"foo"`, `string`, `"foo"`},
+		{`package d2; var _ = []byte(string("foo"))`, `string("foo")`, `string`, `"foo"`},
+		{`package d3; type T []byte; var _ = T("foo")`, `"foo"`, `string`, `"foo"`},
+
+		{`package e0; const _ = float32( 1e-200)`, `float32(1e-200)`, `float32`, `0`},
+		{`package e1; const _ = float32(-1e-200)`, `float32(-1e-200)`, `float32`, `0`},
+		{`package e2; const _ = float64( 1e-2000)`, `float64(1e-2000)`, `float64`, `0`},
+		{`package e3; const _ = float64(-1e-2000)`, `float64(-1e-2000)`, `float64`, `0`},
+		{`package e4; const _ = complex64( 1e-200)`, `complex64(1e-200)`, `complex64`, `0`},
+		{`package e5; const _ = complex64(-1e-200)`, `complex64(-1e-200)`, `complex64`, `0`},
+		{`package e6; const _ = complex128( 1e-2000)`, `complex128(1e-2000)`, `complex128`, `0`},
+		{`package e7; const _ = complex128(-1e-2000)`, `complex128(-1e-2000)`, `complex128`, `0`},
+
+		{`package f0 ; var _ float32 =  1e-200`, `1e-200`, `float32`, `0`},
+		{`package f1 ; var _ float32 = -1e-200`, `-1e-200`, `float32`, `0`},
+		{`package f2a; var _ float64 =  1e-2000`, `1e-2000`, `float64`, `0`},
+		{`package f3a; var _ float64 = -1e-2000`, `-1e-2000`, `float64`, `0`},
+		{`package f2b; var _         =  1e-2000`, `1e-2000`, `float64`, `0`},
+		{`package f3b; var _         = -1e-2000`, `-1e-2000`, `float64`, `0`},
+		{`package f4 ; var _ complex64  =  1e-200 `, `1e-200`, `complex64`, `0`},
+		{`package f5 ; var _ complex64  = -1e-200 `, `-1e-200`, `complex64`, `0`},
+		{`package f6a; var _ complex128 =  1e-2000i`, `1e-2000i`, `complex128`, `0`},
+		{`package f7a; var _ complex128 = -1e-2000i`, `-1e-2000i`, `complex128`, `0`},
+		{`package f6b; var _            =  1e-2000i`, `1e-2000i`, `complex128`, `0`},
+		{`package f7b; var _            = -1e-2000i`, `-1e-2000i`, `complex128`, `0`},
+	}
+
+	for _, test := range tests {
+		info := Info{
+			Types: make(map[ast.Expr]TypeAndValue),
+		}
+		name := mustTypecheck(t, "ValuesInfo", test.src, &info)
+
+		// look for constant expression
+		var expr ast.Expr
+		for e := range info.Types {
+			if ExprString(e) == test.expr {
+				expr = e
+				break
+			}
+		}
+		if expr == nil {
+			t.Errorf("package %s: no expression found for %s", name, test.expr)
+			continue
+		}
+		tv := info.Types[expr]
+
+		// check that type is correct
+		if got := tv.Type.String(); got != test.typ {
+			t.Errorf("package %s: got type %s; want %s", name, got, test.typ)
+			continue
+		}
+
+		// check that value is correct
+		if got := tv.Value.String(); got != test.val {
+			t.Errorf("package %s: got value %s; want %s", name, got, test.val)
+		}
+	}
+}
+
+func TestTypesInfo(t *testing.T) {
+	var tests = []struct {
+		src  string
+		expr string // expression
+		typ  string // value type
+	}{
+		// single-valued expressions of untyped constants
+		{`package b0; var x interface{} = false`, `false`, `bool`},
+		{`package b1; var x interface{} = 0`, `0`, `int`},
+		{`package b2; var x interface{} = 0.`, `0.`, `float64`},
+		{`package b3; var x interface{} = 0i`, `0i`, `complex128`},
+		{`package b4; var x interface{} = "foo"`, `"foo"`, `string`},
+
+		// comma-ok expressions
+		{`package p0; var x interface{}; var _, _ = x.(int)`,
+			`x.(int)`,
+			`(int, bool)`,
+		},
+		{`package p1; var x interface{}; func _() { _, _ = x.(int) }`,
+			`x.(int)`,
+			`(int, bool)`,
+		},
+		// TODO(gri): uncomment if we accept issue 8189.
+		// {`package p2; type mybool bool; var m map[string]complex128; var b mybool; func _() { _, b = m["foo"] }`,
+		// 	`m["foo"]`,
+		// 	`(complex128, p2.mybool)`,
+		// },
+		// TODO(gri): remove if we accept issue 8189.
+		{`package p2; var m map[string]complex128; var b bool; func _() { _, b = m["foo"] }`,
+			`m["foo"]`,
+			`(complex128, bool)`,
+		},
+		{`package p3; var c chan string; var _, _ = <-c`,
+			`<-c`,
+			`(string, bool)`,
+		},
+
+		// issue 6796
+		{`package issue6796_a; var x interface{}; var _, _ = (x.(int))`,
+			`x.(int)`,
+			`(int, bool)`,
+		},
+		{`package issue6796_b; var c chan string; var _, _ = (<-c)`,
+			`(<-c)`,
+			`(string, bool)`,
+		},
+		{`package issue6796_c; var c chan string; var _, _ = (<-c)`,
+			`<-c`,
+			`(string, bool)`,
+		},
+		{`package issue6796_d; var c chan string; var _, _ = ((<-c))`,
+			`(<-c)`,
+			`(string, bool)`,
+		},
+		{`package issue6796_e; func f(c chan string) { _, _ = ((<-c)) }`,
+			`(<-c)`,
+			`(string, bool)`,
+		},
+
+		// issue 7060
+		{`package issue7060_a; var ( m map[int]string; x, ok = m[0] )`,
+			`m[0]`,
+			`(string, bool)`,
+		},
+		{`package issue7060_b; var ( m map[int]string; x, ok interface{} = m[0] )`,
+			`m[0]`,
+			`(string, bool)`,
+		},
+		{`package issue7060_c; func f(x interface{}, ok bool, m map[int]string) { x, ok = m[0] }`,
+			`m[0]`,
+			`(string, bool)`,
+		},
+		{`package issue7060_d; var ( ch chan string; x, ok = <-ch )`,
+			`<-ch`,
+			`(string, bool)`,
+		},
+		{`package issue7060_e; var ( ch chan string; x, ok interface{} = <-ch )`,
+			`<-ch`,
+			`(string, bool)`,
+		},
+		{`package issue7060_f; func f(x interface{}, ok bool, ch chan string) { x, ok = <-ch }`,
+			`<-ch`,
+			`(string, bool)`,
+		},
+	}
+
+	for _, test := range tests {
+		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
+		name := mustTypecheck(t, "TypesInfo", test.src, &info)
+
+		// look for expression type
+		var typ Type
+		for e, tv := range info.Types {
+			if ExprString(e) == test.expr {
+				typ = tv.Type
+				break
+			}
+		}
+		if typ == nil {
+			t.Errorf("package %s: no type found for %s", name, test.expr)
+			continue
+		}
+
+		// check that type is correct
+		if got := typ.String(); got != test.typ {
+			t.Errorf("package %s: got %s; want %s", name, got, test.typ)
+		}
+	}
+}
+
+func predString(tv TypeAndValue) string {
+	var buf bytes.Buffer
+	pred := func(b bool, s string) {
+		if b {
+			if buf.Len() > 0 {
+				buf.WriteString(", ")
+			}
+			buf.WriteString(s)
+		}
+	}
+
+	pred(tv.IsVoid(), "void")
+	pred(tv.IsType(), "type")
+	pred(tv.IsBuiltin(), "builtin")
+	pred(tv.IsValue() && tv.Value != nil, "const")
+	pred(tv.IsValue() && tv.Value == nil, "value")
+	pred(tv.IsNil(), "nil")
+	pred(tv.Addressable(), "addressable")
+	pred(tv.Assignable(), "assignable")
+	pred(tv.HasOk(), "hasOk")
+
+	if buf.Len() == 0 {
+		return "invalid"
+	}
+	return buf.String()
+}
+
+func TestPredicatesInfo(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	var tests = []struct {
+		src  string
+		expr string
+		pred string
+	}{
+		// void
+		{`package n0; func f() { f() }`, `f()`, `void`},
+
+		// types
+		{`package t0; type _ int`, `int`, `type`},
+		{`package t1; type _ []int`, `[]int`, `type`},
+		{`package t2; type _ func()`, `func()`, `type`},
+
+		// built-ins
+		{`package b0; var _ = len("")`, `len`, `builtin`},
+		{`package b1; var _ = (len)("")`, `(len)`, `builtin`},
+
+		// constants
+		{`package c0; var _ = 42`, `42`, `const`},
+		{`package c1; var _ = "foo" + "bar"`, `"foo" + "bar"`, `const`},
+		{`package c2; const (i = 1i; _ = i)`, `i`, `const`},
+
+		// values
+		{`package v0; var (a, b int; _ = a + b)`, `a + b`, `value`},
+		{`package v1; var _ = &[]int{1}`, `([]int literal)`, `value`},
+		{`package v2; var _ = func(){}`, `(func() literal)`, `value`},
+		{`package v4; func f() { _ = f }`, `f`, `value`},
+		{`package v3; var _ *int = nil`, `nil`, `value, nil`},
+		{`package v3; var _ *int = (nil)`, `(nil)`, `value, nil`},
+
+		// addressable (and thus assignable) operands
+		{`package a0; var (x int; _ = x)`, `x`, `value, addressable, assignable`},
+		{`package a1; var (p *int; _ = *p)`, `*p`, `value, addressable, assignable`},
+		{`package a2; var (s []int; _ = s[0])`, `s[0]`, `value, addressable, assignable`},
+		{`package a3; var (s struct{f int}; _ = s.f)`, `s.f`, `value, addressable, assignable`},
+		{`package a4; var (a [10]int; _ = a[0])`, `a[0]`, `value, addressable, assignable`},
+		{`package a5; func _(x int) { _ = x }`, `x`, `value, addressable, assignable`},
+		{`package a6; func _()(x int) { _ = x; return }`, `x`, `value, addressable, assignable`},
+		{`package a7; type T int; func (x T) _() { _ = x }`, `x`, `value, addressable, assignable`},
+		// composite literals are not addressable
+
+		// assignable but not addressable values
+		{`package s0; var (m map[int]int; _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
+		{`package s1; var (m map[int]int; _, _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
+
+		// hasOk expressions
+		{`package k0; var (ch chan int; _ = <-ch)`, `<-ch`, `value, hasOk`},
+		{`package k1; var (ch chan int; _, _ = <-ch)`, `<-ch`, `value, hasOk`},
+
+		// missing entries
+		// - package names are collected in the Uses map
+		// - identifiers being declared are collected in the Defs map
+		{`package m0; import "os"; func _() { _ = os.Stdout }`, `os`, `<missing>`},
+		{`package m1; import p "os"; func _() { _ = p.Stdout }`, `p`, `<missing>`},
+		{`package m2; const c = 0`, `c`, `<missing>`},
+		{`package m3; type T int`, `T`, `<missing>`},
+		{`package m4; var v int`, `v`, `<missing>`},
+		{`package m5; func f() {}`, `f`, `<missing>`},
+		{`package m6; func _(x int) {}`, `x`, `<missing>`},
+		{`package m6; func _()(x int) { return }`, `x`, `<missing>`},
+		{`package m6; type T int; func (x T) _() {}`, `x`, `<missing>`},
+	}
+
+	for _, test := range tests {
+		info := Info{Types: make(map[ast.Expr]TypeAndValue)}
+		name := mustTypecheck(t, "PredicatesInfo", test.src, &info)
+
+		// look for expression predicates
+		got := "<missing>"
+		for e, tv := range info.Types {
+			//println(name, ExprString(e))
+			if ExprString(e) == test.expr {
+				got = predString(tv)
+				break
+			}
+		}
+
+		if got != test.pred {
+			t.Errorf("package %s: got %s; want %s", name, got, test.pred)
+		}
+	}
+}
+
+func TestScopesInfo(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	var tests = []struct {
+		src    string
+		scopes []string // list of scope descriptors of the form kind:varlist
+	}{
+		{`package p0`, []string{
+			"file:",
+		}},
+		{`package p1; import ( "fmt"; m "math"; _ "os" ); var ( _ = fmt.Println; _ = m.Pi )`, []string{
+			"file:fmt m",
+		}},
+		{`package p2; func _() {}`, []string{
+			"file:", "func:",
+		}},
+		{`package p3; func _(x, y int) {}`, []string{
+			"file:", "func:x y",
+		}},
+		{`package p4; func _(x, y int) { x, z := 1, 2; _ = z }`, []string{
+			"file:", "func:x y z", // redeclaration of x
+		}},
+		{`package p5; func _(x, y int) (u, _ int) { return }`, []string{
+			"file:", "func:u x y",
+		}},
+		{`package p6; func _() { { var x int; _ = x } }`, []string{
+			"file:", "func:", "block:x",
+		}},
+		{`package p7; func _() { if true {} }`, []string{
+			"file:", "func:", "if:", "block:",
+		}},
+		{`package p8; func _() { if x := 0; x < 0 { y := x; _ = y } }`, []string{
+			"file:", "func:", "if:x", "block:y",
+		}},
+		{`package p9; func _() { switch x := 0; x {} }`, []string{
+			"file:", "func:", "switch:x",
+		}},
+		{`package p10; func _() { switch x := 0; x { case 1: y := x; _ = y; default: }}`, []string{
+			"file:", "func:", "switch:x", "case:y", "case:",
+		}},
+		{`package p11; func _(t interface{}) { switch t.(type) {} }`, []string{
+			"file:", "func:t", "type switch:",
+		}},
+		{`package p12; func _(t interface{}) { switch t := t; t.(type) {} }`, []string{
+			"file:", "func:t", "type switch:t",
+		}},
+		{`package p13; func _(t interface{}) { switch x := t.(type) { case int: _ = x } }`, []string{
+			"file:", "func:t", "type switch:", "case:x", // x implicitly declared
+		}},
+		{`package p14; func _() { select{} }`, []string{
+			"file:", "func:",
+		}},
+		{`package p15; func _(c chan int) { select{ case <-c: } }`, []string{
+			"file:", "func:c", "comm:",
+		}},
+		{`package p16; func _(c chan int) { select{ case i := <-c: x := i; _ = x} }`, []string{
+			"file:", "func:c", "comm:i x",
+		}},
+		{`package p17; func _() { for{} }`, []string{
+			"file:", "func:", "for:", "block:",
+		}},
+		{`package p18; func _(n int) { for i := 0; i < n; i++ { _ = i } }`, []string{
+			"file:", "func:n", "for:i", "block:",
+		}},
+		{`package p19; func _(a []int) { for i := range a { _ = i} }`, []string{
+			"file:", "func:a", "range:i", "block:",
+		}},
+		{`package p20; var s int; func _(a []int) { for i, x := range a { s += x; _ = i } }`, []string{
+			"file:", "func:a", "range:i x", "block:",
+		}},
+	}
+
+	for _, test := range tests {
+		info := Info{Scopes: make(map[ast.Node]*Scope)}
+		name := mustTypecheck(t, "ScopesInfo", test.src, &info)
+
+		// number of scopes must match
+		if len(info.Scopes) != len(test.scopes) {
+			t.Errorf("package %s: got %d scopes; want %d", name, len(info.Scopes), len(test.scopes))
+		}
+
+		// scope descriptions must match
+		for node, scope := range info.Scopes {
+			kind := "<unknown node kind>"
+			switch node.(type) {
+			case *ast.File:
+				kind = "file"
+			case *ast.FuncType:
+				kind = "func"
+			case *ast.BlockStmt:
+				kind = "block"
+			case *ast.IfStmt:
+				kind = "if"
+			case *ast.SwitchStmt:
+				kind = "switch"
+			case *ast.TypeSwitchStmt:
+				kind = "type switch"
+			case *ast.CaseClause:
+				kind = "case"
+			case *ast.CommClause:
+				kind = "comm"
+			case *ast.ForStmt:
+				kind = "for"
+			case *ast.RangeStmt:
+				kind = "range"
+			}
+
+			// look for matching scope description
+			desc := kind + ":" + strings.Join(scope.Names(), " ")
+			found := false
+			for _, d := range test.scopes {
+				if desc == d {
+					found = true
+					break
+				}
+			}
+			if !found {
+				t.Errorf("package %s: no matching scope found for %s", name, desc)
+			}
+		}
+	}
+}
+
+func TestInitOrderInfo(t *testing.T) {
+	var tests = []struct {
+		src   string
+		inits []string
+	}{
+		{`package p0; var (x = 1; y = x)`, []string{
+			"x = 1", "y = x",
+		}},
+		{`package p1; var (a = 1; b = 2; c = 3)`, []string{
+			"a = 1", "b = 2", "c = 3",
+		}},
+		{`package p2; var (a, b, c = 1, 2, 3)`, []string{
+			"a = 1", "b = 2", "c = 3",
+		}},
+		{`package p3; var _ = f(); func f() int { return 1 }`, []string{
+			"_ = f()", // blank var
+		}},
+		{`package p4; var (a = 0; x = y; y = z; z = 0)`, []string{
+			"a = 0", "z = 0", "y = z", "x = y",
+		}},
+		{`package p5; var (a, _ = m[0]; m map[int]string)`, []string{
+			"a, _ = m[0]", // blank var
+		}},
+		{`package p6; var a, b = f(); func f() (_, _ int) { return z, z }; var z = 0`, []string{
+			"z = 0", "a, b = f()",
+		}},
+		{`package p7; var (a = func() int { return b }(); b = 1)`, []string{
+			"b = 1", "a = (func() int literal)()",
+		}},
+		{`package p8; var (a, b = func() (_, _ int) { return c, c }(); c = 1)`, []string{
+			"c = 1", "a, b = (func() (_, _ int) literal)()",
+		}},
+		{`package p9; type T struct{}; func (T) m() int { _ = y; return 0 }; var x, y = T.m, 1`, []string{
+			"y = 1", "x = T.m",
+		}},
+		{`package p10; var (d = c + b; a = 0; b = 0; c = 0)`, []string{
+			"a = 0", "b = 0", "c = 0", "d = c + b",
+		}},
+		{`package p11; var (a = e + c; b = d + c; c = 0; d = 0; e = 0)`, []string{
+			"c = 0", "d = 0", "b = d + c", "e = 0", "a = e + c",
+		}},
+		// emit an initializer for n:1 initializations only once (not for each node
+		// on the lhs which may appear in different order in the dependency graph)
+		{`package p12; var (a = x; b = 0; x, y = m[0]; m map[int]int)`, []string{
+			"b = 0", "x, y = m[0]", "a = x",
+		}},
+		// test case from spec section on package initialization
+		{`package p12
+
+		var (
+			a = c + b
+			b = f()
+			c = f()
+			d = 3
+		)
+
+		func f() int {
+			d++
+			return d
+		}`, []string{
+			"d = 3", "b = f()", "c = f()", "a = c + b",
+		}},
+		// test case for issue 7131
+		{`package main
+
+		var counter int
+		func next() int { counter++; return counter }
+
+		var _ = makeOrder()
+		func makeOrder() []int { return []int{f, b, d, e, c, a} }
+
+		var a       = next()
+		var b, c    = next(), next()
+		var d, e, f = next(), next(), next()
+		`, []string{
+			"a = next()", "b = next()", "c = next()", "d = next()", "e = next()", "f = next()", "_ = makeOrder()",
+		}},
+	}
+
+	for _, test := range tests {
+		info := Info{}
+		name := mustTypecheck(t, "InitOrderInfo", test.src, &info)
+
+		// number of initializers must match
+		if len(info.InitOrder) != len(test.inits) {
+			t.Errorf("package %s: got %d initializers; want %d", name, len(info.InitOrder), len(test.inits))
+			continue
+		}
+
+		// initializers must match
+		for i, want := range test.inits {
+			got := info.InitOrder[i].String()
+			if got != want {
+				t.Errorf("package %s, init %d: got %s; want %s", name, i, got, want)
+				continue
+			}
+		}
+	}
+}
+
+func TestMultiFileInitOrder(t *testing.T) {
+	fset := token.NewFileSet()
+	mustParse := func(src string) *ast.File {
+		f, err := parser.ParseFile(fset, "main", src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return f
+	}
+
+	fileA := mustParse(`package main; var a = 1`)
+	fileB := mustParse(`package main; var b = 2`)
+
+	// The initialization order must not depend on the parse
+	// order of the files, only on the presentation order to
+	// the type-checker.
+	for _, test := range []struct {
+		files []*ast.File
+		want  string
+	}{
+		{[]*ast.File{fileA, fileB}, "[a = 1 b = 2]"},
+		{[]*ast.File{fileB, fileA}, "[b = 2 a = 1]"},
+	} {
+		var info Info
+		if _, err := new(Config).Check("main", fset, test.files, &info); err != nil {
+			t.Fatal(err)
+		}
+		if got := fmt.Sprint(info.InitOrder); got != test.want {
+			t.Fatalf("got %s; want %s", got, test.want)
+		}
+	}
+}
+
+func TestFiles(t *testing.T) {
+	var sources = []string{
+		"package p; type T struct{}; func (T) m1() {}",
+		"package p; func (T) m2() {}; var x interface{ m1(); m2() } = T{}",
+		"package p; func (T) m3() {}; var y interface{ m1(); m2(); m3() } = T{}",
+		"package p",
+	}
+
+	var conf Config
+	fset := token.NewFileSet()
+	pkg := NewPackage("p", "p")
+	var info Info
+	check := NewChecker(&conf, fset, pkg, &info)
+
+	for i, src := range sources {
+		filename := fmt.Sprintf("sources%d", i)
+		f, err := parser.ParseFile(fset, filename, src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := check.Files([]*ast.File{f}); err != nil {
+			t.Error(err)
+		}
+	}
+
+	// check InitOrder is [x y]
+	var vars []string
+	for _, init := range info.InitOrder {
+		for _, v := range init.Lhs {
+			vars = append(vars, v.Name())
+		}
+	}
+	if got, want := fmt.Sprint(vars), "[x y]"; got != want {
+		t.Errorf("InitOrder == %s, want %s", got, want)
+	}
+}
+
+type testImporter map[string]*Package
+
+func (m testImporter) Import(path string) (*Package, error) {
+	if pkg := m[path]; pkg != nil {
+		return pkg, nil
+	}
+	return nil, fmt.Errorf("package %q not found", path)
+}
+
+func TestSelection(t *testing.T) {
+	selections := make(map[*ast.SelectorExpr]*Selection)
+
+	fset := token.NewFileSet()
+	imports := make(testImporter)
+	conf := Config{Importer: imports}
+	makePkg := func(path, src string) {
+		f, err := parser.ParseFile(fset, path+".go", src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		pkg, err := conf.Check(path, fset, []*ast.File{f}, &Info{Selections: selections})
+		if err != nil {
+			t.Fatal(err)
+		}
+		imports[path] = pkg
+	}
+
+	const libSrc = `
+package lib
+type T float64
+const C T = 3
+var V T
+func F() {}
+func (T) M() {}
+`
+	const mainSrc = `
+package main
+import "lib"
+
+type A struct {
+	*B
+	C
+}
+
+type B struct {
+	b int
+}
+
+func (B) f(int)
+
+type C struct {
+	c int
+}
+
+func (C) g()
+func (*C) h()
+
+func main() {
+	// qualified identifiers
+	var _ lib.T
+        _ = lib.C
+        _ = lib.F
+        _ = lib.V
+	_ = lib.T.M
+
+	// fields
+	_ = A{}.B
+	_ = new(A).B
+
+	_ = A{}.C
+	_ = new(A).C
+
+	_ = A{}.b
+	_ = new(A).b
+
+	_ = A{}.c
+	_ = new(A).c
+
+	// methods
+        _ = A{}.f
+        _ = new(A).f
+        _ = A{}.g
+        _ = new(A).g
+        _ = new(A).h
+
+        _ = B{}.f
+        _ = new(B).f
+
+        _ = C{}.g
+        _ = new(C).g
+        _ = new(C).h
+
+	// method expressions
+        _ = A.f
+        _ = (*A).f
+        _ = B.f
+        _ = (*B).f
+}`
+
+	wantOut := map[string][2]string{
+		"lib.T.M": {"method expr (lib.T) M(lib.T)", ".[0]"},
+
+		"A{}.B":    {"field (main.A) B *main.B", ".[0]"},
+		"new(A).B": {"field (*main.A) B *main.B", "->[0]"},
+		"A{}.C":    {"field (main.A) C main.C", ".[1]"},
+		"new(A).C": {"field (*main.A) C main.C", "->[1]"},
+		"A{}.b":    {"field (main.A) b int", "->[0 0]"},
+		"new(A).b": {"field (*main.A) b int", "->[0 0]"},
+		"A{}.c":    {"field (main.A) c int", ".[1 0]"},
+		"new(A).c": {"field (*main.A) c int", "->[1 0]"},
+
+		"A{}.f":    {"method (main.A) f(int)", "->[0 0]"},
+		"new(A).f": {"method (*main.A) f(int)", "->[0 0]"},
+		"A{}.g":    {"method (main.A) g()", ".[1 0]"},
+		"new(A).g": {"method (*main.A) g()", "->[1 0]"},
+		"new(A).h": {"method (*main.A) h()", "->[1 1]"}, // TODO(gri) should this report .[1 1] ?
+		"B{}.f":    {"method (main.B) f(int)", ".[0]"},
+		"new(B).f": {"method (*main.B) f(int)", "->[0]"},
+		"C{}.g":    {"method (main.C) g()", ".[0]"},
+		"new(C).g": {"method (*main.C) g()", "->[0]"},
+		"new(C).h": {"method (*main.C) h()", "->[1]"}, // TODO(gri) should this report .[1] ?
+
+		"A.f":    {"method expr (main.A) f(main.A, int)", "->[0 0]"},
+		"(*A).f": {"method expr (*main.A) f(*main.A, int)", "->[0 0]"},
+		"B.f":    {"method expr (main.B) f(main.B, int)", ".[0]"},
+		"(*B).f": {"method expr (*main.B) f(*main.B, int)", "->[0]"},
+	}
+
+	makePkg("lib", libSrc)
+	makePkg("main", mainSrc)
+
+	for e, sel := range selections {
+		sel.String() // assertion: must not panic
+
+		start := fset.Position(e.Pos()).Offset
+		end := fset.Position(e.End()).Offset
+		syntax := mainSrc[start:end] // (all SelectorExprs are in main, not lib)
+
+		direct := "."
+		if sel.Indirect() {
+			direct = "->"
+		}
+		got := [2]string{
+			sel.String(),
+			fmt.Sprintf("%s%v", direct, sel.Index()),
+		}
+		want := wantOut[syntax]
+		if want != got {
+			t.Errorf("%s: got %q; want %q", syntax, got, want)
+		}
+		delete(wantOut, syntax)
+
+		// We must explicitly assert properties of the
+		// Signature's receiver since it doesn't participate
+		// in Identical() or String().
+		sig, _ := sel.Type().(*Signature)
+		if sel.Kind() == MethodVal {
+			got := sig.Recv().Type()
+			want := sel.Recv()
+			if !Identical(got, want) {
+				t.Errorf("%s: Recv() = %s, want %s", syntax, got, want)
+			}
+		} else if sig != nil && sig.Recv() != nil {
+			t.Errorf("%s: signature has receiver %s", sig, sig.Recv().Type())
+		}
+	}
+	// Assert that all wantOut entries were used exactly once.
+	for syntax := range wantOut {
+		t.Errorf("no ast.Selection found with syntax %q", syntax)
+	}
+}
+
+func TestIssue8518(t *testing.T) {
+	fset := token.NewFileSet()
+	imports := make(testImporter)
+	conf := Config{
+		Error:    func(err error) { t.Log(err) }, // don't exit after first error
+		Importer: imports,
+	}
+	makePkg := func(path, src string) {
+		f, err := parser.ParseFile(fset, path, src, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		pkg, _ := conf.Check(path, fset, []*ast.File{f}, nil) // errors logged via conf.Error
+		imports[path] = pkg
+	}
+
+	const libSrc = `
+package a
+import "missing"
+const C1 = foo
+const C2 = missing.C
+`
+
+	const mainSrc = `
+package main
+import "a"
+var _ = a.C1
+var _ = a.C2
+`
+
+	makePkg("a", libSrc)
+	makePkg("main", mainSrc) // don't crash when type-checking this package
+}
+
+func TestLookupFieldOrMethod(t *testing.T) {
+	// Test cases assume a lookup of the form a.f or x.f, where a stands for an
+	// addressable value, and x for a non-addressable value (even though a variable
+	// for ease of test case writing).
+	var tests = []struct {
+		src      string
+		found    bool
+		index    []int
+		indirect bool
+	}{
+		// field lookups
+		{"var x T; type T struct{}", false, nil, false},
+		{"var x T; type T struct{ f int }", true, []int{0}, false},
+		{"var x T; type T struct{ a, b, f, c int }", true, []int{2}, false},
+
+		// method lookups
+		{"var a T; type T struct{}; func (T) f() {}", true, []int{0}, false},
+		{"var a *T; type T struct{}; func (T) f() {}", true, []int{0}, true},
+		{"var a T; type T struct{}; func (*T) f() {}", true, []int{0}, false},
+		{"var a *T; type T struct{}; func (*T) f() {}", true, []int{0}, true}, // TODO(gri) should this report indirect = false?
+
+		// collisions
+		{"type ( E1 struct{ f int }; E2 struct{ f int }; x struct{ E1; *E2 })", false, []int{1, 0}, false},
+		{"type ( E1 struct{ f int }; E2 struct{}; x struct{ E1; *E2 }); func (E2) f() {}", false, []int{1, 0}, false},
+
+		// outside methodset
+		// (*T).f method exists, but value of type T is not addressable
+		{"var x T; type T struct{}; func (*T) f() {}", false, nil, true},
+	}
+
+	for _, test := range tests {
+		pkg, err := pkgFor("test", "package p;"+test.src, nil)
+		if err != nil {
+			t.Errorf("%s: incorrect test case: %s", test.src, err)
+			continue
+		}
+
+		obj := pkg.Scope().Lookup("a")
+		if obj == nil {
+			if obj = pkg.Scope().Lookup("x"); obj == nil {
+				t.Errorf("%s: incorrect test case - no object a or x", test.src)
+				continue
+			}
+		}
+
+		f, index, indirect := LookupFieldOrMethod(obj.Type(), obj.Name() == "a", pkg, "f")
+		if (f != nil) != test.found {
+			if f == nil {
+				t.Errorf("%s: got no object; want one", test.src)
+			} else {
+				t.Errorf("%s: got object = %v; want none", test.src, f)
+			}
+		}
+		if !sameSlice(index, test.index) {
+			t.Errorf("%s: got index = %v; want %v", test.src, index, test.index)
+		}
+		if indirect != test.indirect {
+			t.Errorf("%s: got indirect = %v; want %v", test.src, indirect, test.indirect)
+		}
+	}
+}
+
+func sameSlice(a, b []int) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, x := range a {
+		if x != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// TestScopeLookupParent ensures that (*Scope).LookupParent returns
+// the correct result at various positions with the source.
+func TestScopeLookupParent(t *testing.T) {
+	fset := token.NewFileSet()
+	imports := make(testImporter)
+	conf := Config{Importer: imports}
+	mustParse := func(src string) *ast.File {
+		f, err := parser.ParseFile(fset, "dummy.go", src, parser.ParseComments)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return f
+	}
+	var info Info
+	makePkg := func(path string, files ...*ast.File) {
+		imports[path], _ = conf.Check(path, fset, files, &info)
+	}
+
+	makePkg("lib", mustParse("package lib; var X int"))
+	// Each /*name=kind:line*/ comment makes the test look up the
+	// name at that point and checks that it resolves to a decl of
+	// the specified kind and line number.  "undef" means undefined.
+	mainSrc := `
+package main
+import "lib"
+var Y = lib.X
+func f() {
+	print(Y) /*Y=var:4*/
+	z /*z=undef*/ := /*z=undef*/ 1 /*z=var:7*/
+	print(z)
+	/*f=func:5*/ /*lib=pkgname:3*/
+	type /*T=undef*/ T /*T=typename:10*/ *T
+}
+`
+	info.Uses = make(map[*ast.Ident]Object)
+	f := mustParse(mainSrc)
+	makePkg("main", f)
+	mainScope := imports["main"].Scope()
+	rx := regexp.MustCompile(`^/\*(\w*)=([\w:]*)\*/$`)
+	for _, group := range f.Comments {
+		for _, comment := range group.List {
+			// Parse the assertion in the comment.
+			m := rx.FindStringSubmatch(comment.Text)
+			if m == nil {
+				t.Errorf("%s: bad comment: %s",
+					fset.Position(comment.Pos()), comment.Text)
+				continue
+			}
+			name, want := m[1], m[2]
+
+			// Look up the name in the innermost enclosing scope.
+			inner := mainScope.Innermost(comment.Pos())
+			if inner == nil {
+				t.Errorf("%s: at %s: can't find innermost scope",
+					fset.Position(comment.Pos()), comment.Text)
+				continue
+			}
+			got := "undef"
+			if _, obj := inner.LookupParent(name, comment.Pos()); obj != nil {
+				kind := strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
+				got = fmt.Sprintf("%s:%d", kind, fset.Position(obj.Pos()).Line)
+			}
+			if got != want {
+				t.Errorf("%s: at %s: %s resolved to %s, want %s",
+					fset.Position(comment.Pos()), comment.Text, name, got, want)
+			}
+		}
+	}
+
+	// Check that for each referring identifier,
+	// a lookup of its name on the innermost
+	// enclosing scope returns the correct object.
+
+	for id, wantObj := range info.Uses {
+		inner := mainScope.Innermost(id.Pos())
+		if inner == nil {
+			t.Errorf("%s: can't find innermost scope enclosing %q",
+				fset.Position(id.Pos()), id.Name)
+			continue
+		}
+
+		// Exclude selectors and qualified identifiers---lexical
+		// refs only.  (Ideally, we'd see if the AST parent is a
+		// SelectorExpr, but that requires PathEnclosingInterval
+		// from golang.org/x/tools/go/ast/astutil.)
+		if id.Name == "X" {
+			continue
+		}
+
+		_, gotObj := inner.LookupParent(id.Name, id.Pos())
+		if gotObj != wantObj {
+			t.Errorf("%s: got %v, want %v",
+				fset.Position(id.Pos()), gotObj, wantObj)
+			continue
+		}
+	}
+}
diff --git a/libgo/go/go/types/assignments.go b/libgo/go/go/types/assignments.go
new file mode 100644
index 00000000000..e88de56a0da
--- /dev/null
+++ b/libgo/go/go/types/assignments.go
@@ -0,0 +1,328 @@
+// Copyright 2013 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.
+
+// This file implements initialization and assignment checks.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// assignment reports whether x can be assigned to a variable of type T,
+// if necessary by attempting to convert untyped values to the appropriate
+// type. If x.mode == invalid upon return, then assignment has already
+// issued an error message and the caller doesn't have to report another.
+// Use T == nil to indicate assignment to an untyped blank identifier.
+//
+// TODO(gri) Should find a better way to handle in-band errors.
+//
+func (check *Checker) assignment(x *operand, T Type) bool {
+	switch x.mode {
+	case invalid:
+		return true // error reported before
+	case constant_, variable, mapindex, value, commaok:
+		// ok
+	default:
+		unreachable()
+	}
+
+	// x must be a single value
+	// (tuple types are never named - no need for underlying type)
+	if t, _ := x.typ.(*Tuple); t != nil {
+		assert(t.Len() > 1)
+		check.errorf(x.pos(), "%d-valued expression %s used as single value", t.Len(), x)
+		x.mode = invalid
+		return false
+	}
+
+	if isUntyped(x.typ) {
+		target := T
+		// spec: "If an untyped constant is assigned to a variable of interface
+		// type or the blank identifier, the constant is first converted to type
+		// bool, rune, int, float64, complex128 or string respectively, depending
+		// on whether the value is a boolean, rune, integer, floating-point, complex,
+		// or string constant."
+		if T == nil || IsInterface(T) {
+			if T == nil && x.typ == Typ[UntypedNil] {
+				check.errorf(x.pos(), "use of untyped nil")
+				x.mode = invalid
+				return false
+			}
+			target = defaultType(x.typ)
+		}
+		check.convertUntyped(x, target)
+		if x.mode == invalid {
+			return false
+		}
+	}
+
+	// spec: "If a left-hand side is the blank identifier, any typed or
+	// non-constant value except for the predeclared identifier nil may
+	// be assigned to it."
+	return T == nil || x.assignableTo(check.conf, T)
+}
+
+func (check *Checker) initConst(lhs *Const, x *operand) {
+	if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
+		if lhs.typ == nil {
+			lhs.typ = Typ[Invalid]
+		}
+		return
+	}
+
+	// rhs must be a constant
+	if x.mode != constant_ {
+		check.errorf(x.pos(), "%s is not constant", x)
+		if lhs.typ == nil {
+			lhs.typ = Typ[Invalid]
+		}
+		return
+	}
+	assert(isConstType(x.typ))
+
+	// If the lhs doesn't have a type yet, use the type of x.
+	if lhs.typ == nil {
+		lhs.typ = x.typ
+	}
+
+	if !check.assignment(x, lhs.typ) {
+		if x.mode != invalid {
+			check.errorf(x.pos(), "cannot define constant %s (type %s) as %s", lhs.Name(), lhs.typ, x)
+		}
+		return
+	}
+
+	lhs.val = x.val
+}
+
+// If result is set, lhs is a function result parameter and x is a return result.
+func (check *Checker) initVar(lhs *Var, x *operand, result bool) Type {
+	if x.mode == invalid || x.typ == Typ[Invalid] || lhs.typ == Typ[Invalid] {
+		if lhs.typ == nil {
+			lhs.typ = Typ[Invalid]
+		}
+		return nil
+	}
+
+	// If the lhs doesn't have a type yet, use the type of x.
+	if lhs.typ == nil {
+		typ := x.typ
+		if isUntyped(typ) {
+			// convert untyped types to default types
+			if typ == Typ[UntypedNil] {
+				check.errorf(x.pos(), "use of untyped nil")
+				lhs.typ = Typ[Invalid]
+				return nil
+			}
+			typ = defaultType(typ)
+		}
+		lhs.typ = typ
+	}
+
+	if !check.assignment(x, lhs.typ) {
+		if x.mode != invalid {
+			if result {
+				// don't refer to lhs.name because it may be an anonymous result parameter
+				check.errorf(x.pos(), "cannot return %s as value of type %s", x, lhs.typ)
+			} else {
+				check.errorf(x.pos(), "cannot initialize %s with %s", lhs, x)
+			}
+		}
+		return nil
+	}
+
+	return x.typ
+}
+
+func (check *Checker) assignVar(lhs ast.Expr, x *operand) Type {
+	if x.mode == invalid || x.typ == Typ[Invalid] {
+		return nil
+	}
+
+	// Determine if the lhs is a (possibly parenthesized) identifier.
+	ident, _ := unparen(lhs).(*ast.Ident)
+
+	// Don't evaluate lhs if it is the blank identifier.
+	if ident != nil && ident.Name == "_" {
+		check.recordDef(ident, nil)
+		if !check.assignment(x, nil) {
+			assert(x.mode == invalid)
+			x.typ = nil
+		}
+		return x.typ
+	}
+
+	// If the lhs is an identifier denoting a variable v, this assignment
+	// is not a 'use' of v. Remember current value of v.used and restore
+	// after evaluating the lhs via check.expr.
+	var v *Var
+	var v_used bool
+	if ident != nil {
+		if _, obj := check.scope.LookupParent(ident.Name, token.NoPos); obj != nil {
+			v, _ = obj.(*Var)
+			if v != nil {
+				v_used = v.used
+			}
+		}
+	}
+
+	var z operand
+	check.expr(&z, lhs)
+	if v != nil {
+		v.used = v_used // restore v.used
+	}
+
+	if z.mode == invalid || z.typ == Typ[Invalid] {
+		return nil
+	}
+
+	// spec: "Each left-hand side operand must be addressable, a map index
+	// expression, or the blank identifier. Operands may be parenthesized."
+	switch z.mode {
+	case invalid:
+		return nil
+	case variable, mapindex:
+		// ok
+	default:
+		check.errorf(z.pos(), "cannot assign to %s", &z)
+		return nil
+	}
+
+	if !check.assignment(x, z.typ) {
+		if x.mode != invalid {
+			check.errorf(x.pos(), "cannot assign %s to %s", x, &z)
+		}
+		return nil
+	}
+
+	return x.typ
+}
+
+// If returnPos is valid, initVars is called to type-check the assignment of
+// return expressions, and returnPos is the position of the return statement.
+func (check *Checker) initVars(lhs []*Var, rhs []ast.Expr, returnPos token.Pos) {
+	l := len(lhs)
+	get, r, commaOk := unpack(func(x *operand, i int) { check.expr(x, rhs[i]) }, len(rhs), l == 2 && !returnPos.IsValid())
+	if get == nil || l != r {
+		// invalidate lhs and use rhs
+		for _, obj := range lhs {
+			if obj.typ == nil {
+				obj.typ = Typ[Invalid]
+			}
+		}
+		if get == nil {
+			return // error reported by unpack
+		}
+		check.useGetter(get, r)
+		if returnPos.IsValid() {
+			check.errorf(returnPos, "wrong number of return values (want %d, got %d)", l, r)
+			return
+		}
+		check.errorf(rhs[0].Pos(), "assignment count mismatch (%d vs %d)", l, r)
+		return
+	}
+
+	var x operand
+	if commaOk {
+		var a [2]Type
+		for i := range a {
+			get(&x, i)
+			a[i] = check.initVar(lhs[i], &x, returnPos.IsValid())
+		}
+		check.recordCommaOkTypes(rhs[0], a)
+		return
+	}
+
+	for i, lhs := range lhs {
+		get(&x, i)
+		check.initVar(lhs, &x, returnPos.IsValid())
+	}
+}
+
+func (check *Checker) assignVars(lhs, rhs []ast.Expr) {
+	l := len(lhs)
+	get, r, commaOk := unpack(func(x *operand, i int) { check.expr(x, rhs[i]) }, len(rhs), l == 2)
+	if get == nil {
+		return // error reported by unpack
+	}
+	if l != r {
+		check.useGetter(get, r)
+		check.errorf(rhs[0].Pos(), "assignment count mismatch (%d vs %d)", l, r)
+		return
+	}
+
+	var x operand
+	if commaOk {
+		var a [2]Type
+		for i := range a {
+			get(&x, i)
+			a[i] = check.assignVar(lhs[i], &x)
+		}
+		check.recordCommaOkTypes(rhs[0], a)
+		return
+	}
+
+	for i, lhs := range lhs {
+		get(&x, i)
+		check.assignVar(lhs, &x)
+	}
+}
+
+func (check *Checker) shortVarDecl(pos token.Pos, lhs, rhs []ast.Expr) {
+	scope := check.scope
+
+	// collect lhs variables
+	var newVars []*Var
+	var lhsVars = make([]*Var, len(lhs))
+	for i, lhs := range lhs {
+		var obj *Var
+		if ident, _ := lhs.(*ast.Ident); ident != nil {
+			// Use the correct obj if the ident is redeclared. The
+			// variable's scope starts after the declaration; so we
+			// must use Scope.Lookup here and call Scope.Insert
+			// (via check.declare) later.
+			name := ident.Name
+			if alt := scope.Lookup(name); alt != nil {
+				// redeclared object must be a variable
+				if alt, _ := alt.(*Var); alt != nil {
+					obj = alt
+				} else {
+					check.errorf(lhs.Pos(), "cannot assign to %s", lhs)
+				}
+				check.recordUse(ident, alt)
+			} else {
+				// declare new variable, possibly a blank (_) variable
+				obj = NewVar(ident.Pos(), check.pkg, name, nil)
+				if name != "_" {
+					newVars = append(newVars, obj)
+				}
+				check.recordDef(ident, obj)
+			}
+		} else {
+			check.errorf(lhs.Pos(), "cannot declare %s", lhs)
+		}
+		if obj == nil {
+			obj = NewVar(lhs.Pos(), check.pkg, "_", nil) // dummy variable
+		}
+		lhsVars[i] = obj
+	}
+
+	check.initVars(lhsVars, rhs, token.NoPos)
+
+	// declare new variables
+	if len(newVars) > 0 {
+		// spec: "The scope of a constant or variable identifier declared inside
+		// a function begins at the end of the ConstSpec or VarSpec (ShortVarDecl
+		// for short variable declarations) and ends at the end of the innermost
+		// containing block."
+		scopePos := rhs[len(rhs)-1].End()
+		for _, obj := range newVars {
+			check.declare(scope, nil, obj, scopePos) // recordObject already called
+		}
+	} else {
+		check.softErrorf(pos, "no new variables on left side of :=")
+	}
+}
diff --git a/libgo/go/go/types/builtins.go b/libgo/go/go/types/builtins.go
new file mode 100644
index 00000000000..47295914d00
--- /dev/null
+++ b/libgo/go/go/types/builtins.go
@@ -0,0 +1,627 @@
+// 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.
+
+// This file implements typechecking of builtin function calls.
+
+package types
+
+import (
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+// builtin type-checks a call to the built-in specified by id and
+// returns true if the call is valid, with *x holding the result;
+// but x.expr is not set. If the call is invalid, the result is
+// false, and *x is undefined.
+//
+func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ bool) {
+	// append is the only built-in that permits the use of ... for the last argument
+	bin := predeclaredFuncs[id]
+	if call.Ellipsis.IsValid() && id != _Append {
+		check.invalidOp(call.Ellipsis, "invalid use of ... with built-in %s", bin.name)
+		check.use(call.Args...)
+		return
+	}
+
+	// For len(x) and cap(x) we need to know if x contains any function calls or
+	// receive operations. Save/restore current setting and set hasCallOrRecv to
+	// false for the evaluation of x so that we can check it afterwards.
+	// Note: We must do this _before_ calling unpack because unpack evaluates the
+	//       first argument before we even call arg(x, 0)!
+	if id == _Len || id == _Cap {
+		defer func(b bool) {
+			check.hasCallOrRecv = b
+		}(check.hasCallOrRecv)
+		check.hasCallOrRecv = false
+	}
+
+	// determine actual arguments
+	var arg getter
+	nargs := len(call.Args)
+	switch id {
+	default:
+		// make argument getter
+		arg, nargs, _ = unpack(func(x *operand, i int) { check.expr(x, call.Args[i]) }, nargs, false)
+		if arg == nil {
+			return
+		}
+		// evaluate first argument, if present
+		if nargs > 0 {
+			arg(x, 0)
+			if x.mode == invalid {
+				return
+			}
+		}
+	case _Make, _New, _Offsetof, _Trace:
+		// arguments require special handling
+	}
+
+	// check argument count
+	{
+		msg := ""
+		if nargs < bin.nargs {
+			msg = "not enough"
+		} else if !bin.variadic && nargs > bin.nargs {
+			msg = "too many"
+		}
+		if msg != "" {
+			check.invalidOp(call.Rparen, "%s arguments for %s (expected %d, found %d)", msg, call, bin.nargs, nargs)
+			return
+		}
+	}
+
+	switch id {
+	case _Append:
+		// append(s S, x ...T) S, where T is the element type of S
+		// spec: "The variadic function append appends zero or more values x to s of type
+		// S, which must be a slice type, and returns the resulting slice, also of type S.
+		// The values x are passed to a parameter of type ...T where T is the element type
+		// of S and the respective parameter passing rules apply."
+		S := x.typ
+		var T Type
+		if s, _ := S.Underlying().(*Slice); s != nil {
+			T = s.elem
+		} else {
+			check.invalidArg(x.pos(), "%s is not a slice", x)
+			return
+		}
+
+		// remember arguments that have been evaluated already
+		alist := []operand{*x}
+
+		// spec: "As a special case, append also accepts a first argument assignable
+		// to type []byte with a second argument of string type followed by ... .
+		// This form appends the bytes of the string.
+		if nargs == 2 && call.Ellipsis.IsValid() && x.assignableTo(check.conf, NewSlice(universeByte)) {
+			arg(x, 1)
+			if x.mode == invalid {
+				return
+			}
+			if isString(x.typ) {
+				if check.Types != nil {
+					sig := makeSig(S, S, x.typ)
+					sig.variadic = true
+					check.recordBuiltinType(call.Fun, sig)
+				}
+				x.mode = value
+				x.typ = S
+				break
+			}
+			alist = append(alist, *x)
+			// fallthrough
+		}
+
+		// check general case by creating custom signature
+		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
+		sig.variadic = true
+		check.arguments(x, call, sig, func(x *operand, i int) {
+			// only evaluate arguments that have not been evaluated before
+			if i < len(alist) {
+				*x = alist[i]
+				return
+			}
+			arg(x, i)
+		}, nargs)
+		// ok to continue even if check.arguments reported errors
+
+		x.mode = value
+		x.typ = S
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, sig)
+		}
+
+	case _Cap, _Len:
+		// cap(x)
+		// len(x)
+		mode := invalid
+		var typ Type
+		var val constant.Value
+		switch typ = implicitArrayDeref(x.typ.Underlying()); t := typ.(type) {
+		case *Basic:
+			if isString(t) && id == _Len {
+				if x.mode == constant_ {
+					mode = constant_
+					val = constant.MakeInt64(int64(len(constant.StringVal(x.val))))
+				} else {
+					mode = value
+				}
+			}
+
+		case *Array:
+			mode = value
+			// spec: "The expressions len(s) and cap(s) are constants
+			// if the type of s is an array or pointer to an array and
+			// the expression s does not contain channel receives or
+			// function calls; in this case s is not evaluated."
+			if !check.hasCallOrRecv {
+				mode = constant_
+				val = constant.MakeInt64(t.len)
+			}
+
+		case *Slice, *Chan:
+			mode = value
+
+		case *Map:
+			if id == _Len {
+				mode = value
+			}
+		}
+
+		if mode == invalid {
+			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
+			return
+		}
+
+		x.mode = mode
+		x.typ = Typ[Int]
+		x.val = val
+		if check.Types != nil && mode != constant_ {
+			check.recordBuiltinType(call.Fun, makeSig(x.typ, typ))
+		}
+
+	case _Close:
+		// close(c)
+		c, _ := x.typ.Underlying().(*Chan)
+		if c == nil {
+			check.invalidArg(x.pos(), "%s is not a channel", x)
+			return
+		}
+		if c.dir == RecvOnly {
+			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
+			return
+		}
+
+		x.mode = novalue
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(nil, c))
+		}
+
+	case _Complex:
+		// complex(x, y realT) complexT
+		if !check.complexArg(x) {
+			return
+		}
+
+		var y operand
+		arg(&y, 1)
+		if y.mode == invalid {
+			return
+		}
+		if !check.complexArg(&y) {
+			return
+		}
+
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			return
+		}
+
+		if !Identical(x.typ, y.typ) {
+			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
+			return
+		}
+
+		if x.mode == constant_ && y.mode == constant_ {
+			x.val = constant.BinaryOp(x.val, token.ADD, constant.MakeImag(y.val))
+		} else {
+			x.mode = value
+		}
+
+		realT := x.typ
+		complexT := Typ[Invalid]
+		switch realT.Underlying().(*Basic).kind {
+		case Float32:
+			complexT = Typ[Complex64]
+		case Float64:
+			complexT = Typ[Complex128]
+		case UntypedInt, UntypedRune, UntypedFloat:
+			if x.mode == constant_ {
+				realT = defaultType(realT).(*Basic)
+				complexT = Typ[UntypedComplex]
+			} else {
+				// untyped but not constant; probably because one
+				// operand is a non-constant shift of untyped lhs
+				realT = Typ[Float64]
+				complexT = Typ[Complex128]
+			}
+		default:
+			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
+			return
+		}
+
+		x.typ = complexT
+		if check.Types != nil && x.mode != constant_ {
+			check.recordBuiltinType(call.Fun, makeSig(complexT, realT, realT))
+		}
+
+		if x.mode != constant_ {
+			// The arguments have now their final types, which at run-
+			// time will be materialized. Update the expression trees.
+			// If the current types are untyped, the materialized type
+			// is the respective default type.
+			// (If the result is constant, the arguments are never
+			// materialized and there is nothing to do.)
+			check.updateExprType(x.expr, realT, true)
+			check.updateExprType(y.expr, realT, true)
+		}
+
+	case _Copy:
+		// copy(x, y []T) int
+		var dst Type
+		if t, _ := x.typ.Underlying().(*Slice); t != nil {
+			dst = t.elem
+		}
+
+		var y operand
+		arg(&y, 1)
+		if y.mode == invalid {
+			return
+		}
+		var src Type
+		switch t := y.typ.Underlying().(type) {
+		case *Basic:
+			if isString(y.typ) {
+				src = universeByte
+			}
+		case *Slice:
+			src = t.elem
+		}
+
+		if dst == nil || src == nil {
+			check.invalidArg(x.pos(), "copy expects slice arguments; found %s and %s", x, &y)
+			return
+		}
+
+		if !Identical(dst, src) {
+			check.invalidArg(x.pos(), "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
+			return
+		}
+
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(Typ[Int], x.typ, y.typ))
+		}
+		x.mode = value
+		x.typ = Typ[Int]
+
+	case _Delete:
+		// delete(m, k)
+		m, _ := x.typ.Underlying().(*Map)
+		if m == nil {
+			check.invalidArg(x.pos(), "%s is not a map", x)
+			return
+		}
+		arg(x, 1) // k
+		if x.mode == invalid {
+			return
+		}
+
+		if !x.assignableTo(check.conf, m.key) {
+			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.key)
+			return
+		}
+
+		x.mode = novalue
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+		}
+
+	case _Imag, _Real:
+		// imag(complexT) realT
+		// real(complexT) realT
+		if !isComplex(x.typ) {
+			check.invalidArg(x.pos(), "%s must be a complex number", x)
+			return
+		}
+		if x.mode == constant_ {
+			if id == _Real {
+				x.val = constant.Real(x.val)
+			} else {
+				x.val = constant.Imag(x.val)
+			}
+		} else {
+			x.mode = value
+		}
+		var k BasicKind
+		switch x.typ.Underlying().(*Basic).kind {
+		case Complex64:
+			k = Float32
+		case Complex128:
+			k = Float64
+		case UntypedComplex:
+			k = UntypedFloat
+		default:
+			unreachable()
+		}
+
+		if check.Types != nil && x.mode != constant_ {
+			check.recordBuiltinType(call.Fun, makeSig(Typ[k], x.typ))
+		}
+		x.typ = Typ[k]
+
+	case _Make:
+		// make(T, n)
+		// make(T, n, m)
+		// (no argument evaluated yet)
+		arg0 := call.Args[0]
+		T := check.typ(arg0)
+		if T == Typ[Invalid] {
+			return
+		}
+
+		var min int // minimum number of arguments
+		switch T.Underlying().(type) {
+		case *Slice:
+			min = 2
+		case *Map, *Chan:
+			min = 1
+		default:
+			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
+			return
+		}
+		if nargs < min || min+1 < nargs {
+			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, nargs)
+			return
+		}
+		var sizes []int64 // constant integer arguments, if any
+		for _, arg := range call.Args[1:] {
+			if s, ok := check.index(arg, -1); ok && s >= 0 {
+				sizes = append(sizes, s)
+			}
+		}
+		if len(sizes) == 2 && sizes[0] > sizes[1] {
+			check.invalidArg(call.Args[1].Pos(), "length and capacity swapped")
+			// safe to continue
+		}
+		x.mode = value
+		x.typ = T
+		if check.Types != nil {
+			params := [...]Type{T, Typ[Int], Typ[Int]}
+			check.recordBuiltinType(call.Fun, makeSig(x.typ, params[:1+len(sizes)]...))
+		}
+
+	case _New:
+		// new(T)
+		// (no argument evaluated yet)
+		T := check.typ(call.Args[0])
+		if T == Typ[Invalid] {
+			return
+		}
+
+		x.mode = value
+		x.typ = &Pointer{base: T}
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(x.typ, T))
+		}
+
+	case _Panic:
+		// panic(x)
+		T := new(Interface)
+		if !check.assignment(x, T) {
+			assert(x.mode == invalid)
+			return
+		}
+
+		x.mode = novalue
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(nil, T))
+		}
+
+	case _Print, _Println:
+		// print(x, y, ...)
+		// println(x, y, ...)
+		var params []Type
+		if nargs > 0 {
+			params = make([]Type, nargs)
+			for i := 0; i < nargs; i++ {
+				if i > 0 {
+					arg(x, i) // first argument already evaluated
+				}
+				if !check.assignment(x, nil) {
+					assert(x.mode == invalid)
+					return
+				}
+				params[i] = x.typ
+			}
+		}
+
+		x.mode = novalue
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(nil, params...))
+		}
+
+	case _Recover:
+		// recover() interface{}
+		x.mode = value
+		x.typ = new(Interface)
+		if check.Types != nil {
+			check.recordBuiltinType(call.Fun, makeSig(x.typ))
+		}
+
+	case _Alignof:
+		// unsafe.Alignof(x T) uintptr
+		if !check.assignment(x, nil) {
+			assert(x.mode == invalid)
+			return
+		}
+
+		x.mode = constant_
+		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
+		x.typ = Typ[Uintptr]
+		// result is constant - no need to record signature
+
+	case _Offsetof:
+		// unsafe.Offsetof(x T) uintptr, where x must be a selector
+		// (no argument evaluated yet)
+		arg0 := call.Args[0]
+		selx, _ := unparen(arg0).(*ast.SelectorExpr)
+		if selx == nil {
+			check.invalidArg(arg0.Pos(), "%s is not a selector expression", arg0)
+			check.use(arg0)
+			return
+		}
+
+		check.expr(x, selx.X)
+		if x.mode == invalid {
+			return
+		}
+
+		base := derefStructPtr(x.typ)
+		sel := selx.Sel.Name
+		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
+		switch obj.(type) {
+		case nil:
+			check.invalidArg(x.pos(), "%s has no single field %s", base, sel)
+			return
+		case *Func:
+			// TODO(gri) Using derefStructPtr may result in methods being found
+			// that don't actually exist. An error either way, but the error
+			// message is confusing. See: https://play.golang.org/p/al75v23kUy ,
+			// but go/types reports: "invalid argument: x.m is a method value".
+			check.invalidArg(arg0.Pos(), "%s is a method value", arg0)
+			return
+		}
+		if indirect {
+			check.invalidArg(x.pos(), "field %s is embedded via a pointer in %s", sel, base)
+			return
+		}
+
+		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
+		check.recordSelection(selx, FieldVal, base, obj, index, false)
+
+		offs := check.conf.offsetof(base, index)
+		x.mode = constant_
+		x.val = constant.MakeInt64(offs)
+		x.typ = Typ[Uintptr]
+		// result is constant - no need to record signature
+
+	case _Sizeof:
+		// unsafe.Sizeof(x T) uintptr
+		if !check.assignment(x, nil) {
+			assert(x.mode == invalid)
+			return
+		}
+
+		x.mode = constant_
+		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
+		x.typ = Typ[Uintptr]
+		// result is constant - no need to record signature
+
+	case _Assert:
+		// assert(pred) causes a typechecker error if pred is false.
+		// The result of assert is the value of pred if there is no error.
+		// Note: assert is only available in self-test mode.
+		if x.mode != constant_ || !isBoolean(x.typ) {
+			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
+			return
+		}
+		if x.val.Kind() != constant.Bool {
+			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
+			return
+		}
+		if !constant.BoolVal(x.val) {
+			check.errorf(call.Pos(), "%s failed", call)
+			// compile-time assertion failure - safe to continue
+		}
+		// result is constant - no need to record signature
+
+	case _Trace:
+		// trace(x, y, z, ...) dumps the positions, expressions, and
+		// values of its arguments. The result of trace is the value
+		// of the first argument.
+		// Note: trace is only available in self-test mode.
+		// (no argument evaluated yet)
+		if nargs == 0 {
+			check.dump("%s: trace() without arguments", call.Pos())
+			x.mode = novalue
+			break
+		}
+		var t operand
+		x1 := x
+		for _, arg := range call.Args {
+			check.rawExpr(x1, arg, nil) // permit trace for types, e.g.: new(trace(T))
+			check.dump("%s: %s", x1.pos(), x1)
+			x1 = &t // use incoming x only for first argument
+		}
+		// trace is only available in test mode - no need to record signature
+
+	default:
+		unreachable()
+	}
+
+	return true
+}
+
+// makeSig makes a signature for the given argument and result types.
+// Default types are used for untyped arguments, and res may be nil.
+func makeSig(res Type, args ...Type) *Signature {
+	list := make([]*Var, len(args))
+	for i, param := range args {
+		list[i] = NewVar(token.NoPos, nil, "", defaultType(param))
+	}
+	params := NewTuple(list...)
+	var result *Tuple
+	if res != nil {
+		assert(!isUntyped(res))
+		result = NewTuple(NewVar(token.NoPos, nil, "", res))
+	}
+	return &Signature{params: params, results: result}
+}
+
+// implicitArrayDeref returns A if typ is of the form *A and A is an array;
+// otherwise it returns typ.
+//
+func implicitArrayDeref(typ Type) Type {
+	if p, ok := typ.(*Pointer); ok {
+		if a, ok := p.base.Underlying().(*Array); ok {
+			return a
+		}
+	}
+	return typ
+}
+
+// unparen returns e with any enclosing parentheses stripped.
+func unparen(e ast.Expr) ast.Expr {
+	for {
+		p, ok := e.(*ast.ParenExpr)
+		if !ok {
+			return e
+		}
+		e = p.X
+	}
+}
+
+func (check *Checker) complexArg(x *operand) bool {
+	t, _ := x.typ.Underlying().(*Basic)
+	if t != nil && (t.info&IsFloat != 0 || t.kind == UntypedInt || t.kind == UntypedRune) {
+		return true
+	}
+	check.invalidArg(x.pos(), "%s must be a float32, float64, or an untyped non-complex numeric constant", x)
+	return false
+}
diff --git a/libgo/go/go/types/builtins_test.go b/libgo/go/go/types/builtins_test.go
new file mode 100644
index 00000000000..9835a482670
--- /dev/null
+++ b/libgo/go/go/types/builtins_test.go
@@ -0,0 +1,204 @@
+// Copyright 2013 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 types_test
+
+import (
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"testing"
+
+	. "go/types"
+)
+
+var builtinCalls = []struct {
+	name, src, sig string
+}{
+	{"append", `var s []int; _ = append(s)`, `func([]int, ...int) []int`},
+	{"append", `var s []int; _ = append(s, 0)`, `func([]int, ...int) []int`},
+	{"append", `var s []int; _ = (append)(s, 0)`, `func([]int, ...int) []int`},
+	{"append", `var s []byte; _ = ((append))(s, 0)`, `func([]byte, ...byte) []byte`},
+	{"append", `var s []byte; _ = append(s, "foo"...)`, `func([]byte, string...) []byte`},
+	{"append", `type T []byte; var s T; var str string; _ = append(s, str...)`, `func(p.T, string...) p.T`},
+	{"append", `type T []byte; type U string; var s T; var str U; _ = append(s, str...)`, `func(p.T, p.U...) p.T`},
+
+	{"cap", `var s [10]int; _ = cap(s)`, `invalid type`},  // constant
+	{"cap", `var s [10]int; _ = cap(&s)`, `invalid type`}, // constant
+	{"cap", `var s []int64; _ = cap(s)`, `func([]int64) int`},
+	{"cap", `var c chan<-bool; _ = cap(c)`, `func(chan<- bool) int`},
+
+	{"len", `_ = len("foo")`, `invalid type`}, // constant
+	{"len", `var s string; _ = len(s)`, `func(string) int`},
+	{"len", `var s [10]int; _ = len(s)`, `invalid type`},  // constant
+	{"len", `var s [10]int; _ = len(&s)`, `invalid type`}, // constant
+	{"len", `var s []int64; _ = len(s)`, `func([]int64) int`},
+	{"len", `var c chan<-bool; _ = len(c)`, `func(chan<- bool) int`},
+	{"len", `var m map[string]float32; _ = len(m)`, `func(map[string]float32) int`},
+
+	{"close", `var c chan int; close(c)`, `func(chan int)`},
+	{"close", `var c chan<- chan string; close(c)`, `func(chan<- chan string)`},
+
+	{"complex", `_ = complex(1, 0)`, `invalid type`}, // constant
+	{"complex", `var re float32; _ = complex(re, 1.0)`, `func(float32, float32) complex64`},
+	{"complex", `var im float64; _ = complex(1, im)`, `func(float64, float64) complex128`},
+	{"complex", `type F32 float32; var re, im F32; _ = complex(re, im)`, `func(p.F32, p.F32) complex64`},
+	{"complex", `type F64 float64; var re, im F64; _ = complex(re, im)`, `func(p.F64, p.F64) complex128`},
+
+	{"copy", `var src, dst []byte; copy(dst, src)`, `func([]byte, []byte) int`},
+	{"copy", `type T [][]int; var src, dst T; _ = copy(dst, src)`, `func(p.T, p.T) int`},
+	{"copy", `var src string; var dst []byte; copy(dst, src)`, `func([]byte, string) int`},
+	{"copy", `type T string; type U []byte; var src T; var dst U; copy(dst, src)`, `func(p.U, p.T) int`},
+	{"copy", `var dst []byte; copy(dst, "hello")`, `func([]byte, string) int`},
+
+	{"delete", `var m map[string]bool; delete(m, "foo")`, `func(map[string]bool, string)`},
+	{"delete", `type (K string; V int); var m map[K]V; delete(m, "foo")`, `func(map[p.K]p.V, p.K)`},
+
+	{"imag", `_ = imag(1i)`, `invalid type`}, // constant
+	{"imag", `var c complex64; _ = imag(c)`, `func(complex64) float32`},
+	{"imag", `var c complex128; _ = imag(c)`, `func(complex128) float64`},
+	{"imag", `type C64 complex64; var c C64; _ = imag(c)`, `func(p.C64) float32`},
+	{"imag", `type C128 complex128; var c C128; _ = imag(c)`, `func(p.C128) float64`},
+
+	{"real", `_ = real(1i)`, `invalid type`}, // constant
+	{"real", `var c complex64; _ = real(c)`, `func(complex64) float32`},
+	{"real", `var c complex128; _ = real(c)`, `func(complex128) float64`},
+	{"real", `type C64 complex64; var c C64; _ = real(c)`, `func(p.C64) float32`},
+	{"real", `type C128 complex128; var c C128; _ = real(c)`, `func(p.C128) float64`},
+
+	{"make", `_ = make([]int, 10)`, `func([]int, int) []int`},
+	{"make", `type T []byte; _ = make(T, 10, 20)`, `func(p.T, int, int) p.T`},
+
+	{"new", `_ = new(int)`, `func(int) *int`},
+	{"new", `type T struct{}; _ = new(T)`, `func(p.T) *p.T`},
+
+	{"panic", `panic(0)`, `func(interface{})`},
+	{"panic", `panic("foo")`, `func(interface{})`},
+
+	{"print", `print()`, `func()`},
+	{"print", `print(0)`, `func(int)`},
+	{"print", `print(1, 2.0, "foo", true)`, `func(int, float64, string, bool)`},
+
+	{"println", `println()`, `func()`},
+	{"println", `println(0)`, `func(int)`},
+	{"println", `println(1, 2.0, "foo", true)`, `func(int, float64, string, bool)`},
+
+	{"recover", `recover()`, `func() interface{}`},
+	{"recover", `_ = recover()`, `func() interface{}`},
+
+	{"Alignof", `_ = unsafe.Alignof(0)`, `invalid type`},                 // constant
+	{"Alignof", `var x struct{}; _ = unsafe.Alignof(x)`, `invalid type`}, // constant
+
+	{"Offsetof", `var x struct{f bool}; _ = unsafe.Offsetof(x.f)`, `invalid type`},           // constant
+	{"Offsetof", `var x struct{_ int; f bool}; _ = unsafe.Offsetof((&x).f)`, `invalid type`}, // constant
+
+	{"Sizeof", `_ = unsafe.Sizeof(0)`, `invalid type`},                 // constant
+	{"Sizeof", `var x struct{}; _ = unsafe.Sizeof(x)`, `invalid type`}, // constant
+
+	{"assert", `assert(true)`, `invalid type`},                                    // constant
+	{"assert", `type B bool; const pred B = 1 < 2; assert(pred)`, `invalid type`}, // constant
+
+	// no tests for trace since it produces output as a side-effect
+}
+
+func TestBuiltinSignatures(t *testing.T) {
+	DefPredeclaredTestFuncs()
+
+	seen := map[string]bool{"trace": true} // no test for trace built-in; add it manually
+	for _, call := range builtinCalls {
+		testBuiltinSignature(t, call.name, call.src, call.sig)
+		seen[call.name] = true
+	}
+
+	// make sure we didn't miss one
+	for _, name := range Universe.Names() {
+		if _, ok := Universe.Lookup(name).(*Builtin); ok && !seen[name] {
+			t.Errorf("missing test for %s", name)
+		}
+	}
+	for _, name := range Unsafe.Scope().Names() {
+		if _, ok := Unsafe.Scope().Lookup(name).(*Builtin); ok && !seen[name] {
+			t.Errorf("missing test for unsafe.%s", name)
+		}
+	}
+}
+
+func testBuiltinSignature(t *testing.T, name, src0, want string) {
+	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _() { %s }`, src0)
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Errorf("%s: %s", src0, err)
+		return
+	}
+
+	conf := Config{Importer: importer.Default()}
+	uses := make(map[*ast.Ident]Object)
+	types := make(map[ast.Expr]TypeAndValue)
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Uses: uses, Types: types})
+	if err != nil {
+		t.Errorf("%s: %s", src0, err)
+		return
+	}
+
+	// find called function
+	n := 0
+	var fun ast.Expr
+	for x := range types {
+		if call, _ := x.(*ast.CallExpr); call != nil {
+			fun = call.Fun
+			n++
+		}
+	}
+	if n != 1 {
+		t.Errorf("%s: got %d CallExprs; want 1", src0, n)
+		return
+	}
+
+	// check recorded types for fun and descendents (may be parenthesized)
+	for {
+		// the recorded type for the built-in must match the wanted signature
+		typ := types[fun].Type
+		if typ == nil {
+			t.Errorf("%s: no type recorded for %s", src0, ExprString(fun))
+			return
+		}
+		if got := typ.String(); got != want {
+			t.Errorf("%s: got type %s; want %s", src0, got, want)
+			return
+		}
+
+		// called function must be a (possibly parenthesized, qualified)
+		// identifier denoting the expected built-in
+		switch p := fun.(type) {
+		case *ast.Ident:
+			obj := uses[p]
+			if obj == nil {
+				t.Errorf("%s: no object found for %s", src0, p)
+				return
+			}
+			bin, _ := obj.(*Builtin)
+			if bin == nil {
+				t.Errorf("%s: %s does not denote a built-in", src0, p)
+				return
+			}
+			if bin.Name() != name {
+				t.Errorf("%s: got built-in %s; want %s", src0, bin.Name(), name)
+				return
+			}
+			return // we're done
+
+		case *ast.ParenExpr:
+			fun = p.X // unpack
+
+		case *ast.SelectorExpr:
+			// built-in from package unsafe - ignore details
+			return // we're done
+
+		default:
+			t.Errorf("%s: invalid function call", src0)
+			return
+		}
+	}
+}
diff --git a/libgo/go/go/types/call.go b/libgo/go/go/types/call.go
new file mode 100644
index 00000000000..62cefc047ef
--- /dev/null
+++ b/libgo/go/go/types/call.go
@@ -0,0 +1,441 @@
+// Copyright 2013 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.
+
+// This file implements typechecking of call and selector expressions.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+func (check *Checker) call(x *operand, e *ast.CallExpr) exprKind {
+	check.exprOrType(x, e.Fun)
+
+	switch x.mode {
+	case invalid:
+		check.use(e.Args...)
+		x.mode = invalid
+		x.expr = e
+		return statement
+
+	case typexpr:
+		// conversion
+		T := x.typ
+		x.mode = invalid
+		switch n := len(e.Args); n {
+		case 0:
+			check.errorf(e.Rparen, "missing argument in conversion to %s", T)
+		case 1:
+			check.expr(x, e.Args[0])
+			if x.mode != invalid {
+				check.conversion(x, T)
+			}
+		default:
+			check.errorf(e.Args[n-1].Pos(), "too many arguments in conversion to %s", T)
+		}
+		x.expr = e
+		return conversion
+
+	case builtin:
+		id := x.id
+		if !check.builtin(x, e, id) {
+			x.mode = invalid
+		}
+		x.expr = e
+		// a non-constant result implies a function call
+		if x.mode != invalid && x.mode != constant_ {
+			check.hasCallOrRecv = true
+		}
+		return predeclaredFuncs[id].kind
+
+	default:
+		// function/method call
+		sig, _ := x.typ.Underlying().(*Signature)
+		if sig == nil {
+			check.invalidOp(x.pos(), "cannot call non-function %s", x)
+			x.mode = invalid
+			x.expr = e
+			return statement
+		}
+
+		arg, n, _ := unpack(func(x *operand, i int) { check.expr(x, e.Args[i]) }, len(e.Args), false)
+		if arg == nil {
+			x.mode = invalid
+			x.expr = e
+			return statement
+		}
+
+		check.arguments(x, e, sig, arg, n)
+
+		// determine result
+		switch sig.results.Len() {
+		case 0:
+			x.mode = novalue
+		case 1:
+			x.mode = value
+			x.typ = sig.results.vars[0].typ // unpack tuple
+		default:
+			x.mode = value
+			x.typ = sig.results
+		}
+		x.expr = e
+		check.hasCallOrRecv = true
+
+		return statement
+	}
+}
+
+// use type-checks each argument.
+// Useful to make sure expressions are evaluated
+// (and variables are "used") in the presence of other errors.
+func (check *Checker) use(arg ...ast.Expr) {
+	var x operand
+	for _, e := range arg {
+		check.rawExpr(&x, e, nil)
+	}
+}
+
+// useGetter is like use, but takes a getter instead of a list of expressions.
+// It should be called instead of use if a getter is present to avoid repeated
+// evaluation of the first argument (since the getter was likely obtained via
+// unpack, which may have evaluated the first argument already).
+func (check *Checker) useGetter(get getter, n int) {
+	var x operand
+	for i := 0; i < n; i++ {
+		get(&x, i)
+	}
+}
+
+// A getter sets x as the i'th operand, where 0 <= i < n and n is the total
+// number of operands (context-specific, and maintained elsewhere). A getter
+// type-checks the i'th operand; the details of the actual check are getter-
+// specific.
+type getter func(x *operand, i int)
+
+// unpack takes a getter get and a number of operands n. If n == 1, unpack
+// calls the incoming getter for the first operand. If that operand is
+// invalid, unpack returns (nil, 0, false). Otherwise, if that operand is a
+// function call, or a comma-ok expression and allowCommaOk is set, the result
+// is a new getter and operand count providing access to the function results,
+// or comma-ok values, respectively. The third result value reports if it
+// is indeed the comma-ok case. In all other cases, the incoming getter and
+// operand count are returned unchanged, and the third result value is false.
+//
+// In other words, if there's exactly one operand that - after type-checking
+// by calling get - stands for multiple operands, the resulting getter provides
+// access to those operands instead.
+//
+// If the returned getter is called at most once for a given operand index i
+// (including i == 0), that operand is guaranteed to cause only one call of
+// the incoming getter with that i.
+//
+func unpack(get getter, n int, allowCommaOk bool) (getter, int, bool) {
+	if n == 1 {
+		// possibly result of an n-valued function call or comma,ok value
+		var x0 operand
+		get(&x0, 0)
+		if x0.mode == invalid {
+			return nil, 0, false
+		}
+
+		if t, ok := x0.typ.(*Tuple); ok {
+			// result of an n-valued function call
+			return func(x *operand, i int) {
+				x.mode = value
+				x.expr = x0.expr
+				x.typ = t.At(i).typ
+			}, t.Len(), false
+		}
+
+		if x0.mode == mapindex || x0.mode == commaok {
+			// comma-ok value
+			if allowCommaOk {
+				a := [2]Type{x0.typ, Typ[UntypedBool]}
+				return func(x *operand, i int) {
+					x.mode = value
+					x.expr = x0.expr
+					x.typ = a[i]
+				}, 2, true
+			}
+			x0.mode = value
+		}
+
+		// single value
+		return func(x *operand, i int) {
+			if i != 0 {
+				unreachable()
+			}
+			*x = x0
+		}, 1, false
+	}
+
+	// zero or multiple values
+	return get, n, false
+}
+
+// arguments checks argument passing for the call with the given signature.
+// The arg function provides the operand for the i'th argument.
+func (check *Checker) arguments(x *operand, call *ast.CallExpr, sig *Signature, arg getter, n int) {
+	if call.Ellipsis.IsValid() {
+		// last argument is of the form x...
+		if len(call.Args) == 1 && n > 1 {
+			// f()... is not permitted if f() is multi-valued
+			check.errorf(call.Ellipsis, "cannot use ... with %d-valued expression %s", n, call.Args[0])
+			check.useGetter(arg, n)
+			return
+		}
+		if !sig.variadic {
+			check.errorf(call.Ellipsis, "cannot use ... in call to non-variadic %s", call.Fun)
+			check.useGetter(arg, n)
+			return
+		}
+	}
+
+	// evaluate arguments
+	for i := 0; i < n; i++ {
+		arg(x, i)
+		if x.mode != invalid {
+			var ellipsis token.Pos
+			if i == n-1 && call.Ellipsis.IsValid() {
+				ellipsis = call.Ellipsis
+			}
+			check.argument(sig, i, x, ellipsis)
+		}
+	}
+
+	// check argument count
+	if sig.variadic {
+		// a variadic function accepts an "empty"
+		// last argument: count one extra
+		n++
+	}
+	if n < sig.params.Len() {
+		check.errorf(call.Rparen, "too few arguments in call to %s", call.Fun)
+		// ok to continue
+	}
+}
+
+// argument checks passing of argument x to the i'th parameter of the given signature.
+// If ellipsis is valid, the argument is followed by ... at that position in the call.
+func (check *Checker) argument(sig *Signature, i int, x *operand, ellipsis token.Pos) {
+	n := sig.params.Len()
+
+	// determine parameter type
+	var typ Type
+	switch {
+	case i < n:
+		typ = sig.params.vars[i].typ
+	case sig.variadic:
+		typ = sig.params.vars[n-1].typ
+		if debug {
+			if _, ok := typ.(*Slice); !ok {
+				check.dump("%s: expected unnamed slice type, got %s", sig.params.vars[n-1].Pos(), typ)
+			}
+		}
+	default:
+		check.errorf(x.pos(), "too many arguments")
+		return
+	}
+
+	if ellipsis.IsValid() {
+		// argument is of the form x...
+		if i != n-1 {
+			check.errorf(ellipsis, "can only use ... with matching parameter")
+			return
+		}
+		switch t := x.typ.Underlying().(type) {
+		case *Slice:
+			// ok
+		case *Tuple:
+			check.errorf(ellipsis, "cannot use ... with %d-valued expression %s", t.Len(), x)
+			return
+		default:
+			check.errorf(x.pos(), "cannot use %s as parameter of type %s", x, typ)
+			return
+		}
+	} else if sig.variadic && i >= n-1 {
+		// use the variadic parameter slice's element type
+		typ = typ.(*Slice).elem
+	}
+
+	if !check.assignment(x, typ) && x.mode != invalid {
+		check.errorf(x.pos(), "cannot pass argument %s to parameter of type %s", x, typ)
+	}
+}
+
+func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
+	// these must be declared before the "goto Error" statements
+	var (
+		obj      Object
+		index    []int
+		indirect bool
+	)
+
+	sel := e.Sel.Name
+	// If the identifier refers to a package, handle everything here
+	// so we don't need a "package" mode for operands: package names
+	// can only appear in qualified identifiers which are mapped to
+	// selector expressions.
+	if ident, ok := e.X.(*ast.Ident); ok {
+		_, obj := check.scope.LookupParent(ident.Name, check.pos)
+		if pkg, _ := obj.(*PkgName); pkg != nil {
+			assert(pkg.pkg == check.pkg)
+			check.recordUse(ident, pkg)
+			pkg.used = true
+			exp := pkg.imported.scope.Lookup(sel)
+			if exp == nil {
+				if !pkg.imported.fake {
+					check.errorf(e.Pos(), "%s not declared by package %s", sel, ident)
+				}
+				goto Error
+			}
+			if !exp.Exported() {
+				check.errorf(e.Pos(), "%s not exported by package %s", sel, ident)
+				// ok to continue
+			}
+			check.recordUse(e.Sel, exp)
+			// Simplified version of the code for *ast.Idents:
+			// - imported objects are always fully initialized
+			switch exp := exp.(type) {
+			case *Const:
+				assert(exp.Val() != nil)
+				x.mode = constant_
+				x.typ = exp.typ
+				x.val = exp.val
+			case *TypeName:
+				x.mode = typexpr
+				x.typ = exp.typ
+			case *Var:
+				x.mode = variable
+				x.typ = exp.typ
+			case *Func:
+				x.mode = value
+				x.typ = exp.typ
+			case *Builtin:
+				x.mode = builtin
+				x.typ = exp.typ
+				x.id = exp.id
+			default:
+				unreachable()
+			}
+			x.expr = e
+			return
+		}
+	}
+
+	check.exprOrType(x, e.X)
+	if x.mode == invalid {
+		goto Error
+	}
+
+	obj, index, indirect = LookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel)
+	if obj == nil {
+		switch {
+		case index != nil:
+			// TODO(gri) should provide actual type where the conflict happens
+			check.invalidOp(e.Pos(), "ambiguous selector %s", sel)
+		case indirect:
+			check.invalidOp(e.Pos(), "%s is not in method set of %s", sel, x.typ)
+		default:
+			check.invalidOp(e.Pos(), "%s has no field or method %s", x, sel)
+		}
+		goto Error
+	}
+
+	if x.mode == typexpr {
+		// method expression
+		m, _ := obj.(*Func)
+		if m == nil {
+			check.invalidOp(e.Pos(), "%s has no method %s", x, sel)
+			goto Error
+		}
+
+		check.recordSelection(e, MethodExpr, x.typ, m, index, indirect)
+
+		// the receiver type becomes the type of the first function
+		// argument of the method expression's function type
+		var params []*Var
+		sig := m.typ.(*Signature)
+		if sig.params != nil {
+			params = sig.params.vars
+		}
+		x.mode = value
+		x.typ = &Signature{
+			params:   NewTuple(append([]*Var{NewVar(token.NoPos, check.pkg, "", x.typ)}, params...)...),
+			results:  sig.results,
+			variadic: sig.variadic,
+		}
+
+		check.addDeclDep(m)
+
+	} else {
+		// regular selector
+		switch obj := obj.(type) {
+		case *Var:
+			check.recordSelection(e, FieldVal, x.typ, obj, index, indirect)
+			if x.mode == variable || indirect {
+				x.mode = variable
+			} else {
+				x.mode = value
+			}
+			x.typ = obj.typ
+
+		case *Func:
+			// TODO(gri) If we needed to take into account the receiver's
+			// addressability, should we report the type &(x.typ) instead?
+			check.recordSelection(e, MethodVal, x.typ, obj, index, indirect)
+
+			if debug {
+				// Verify that LookupFieldOrMethod and MethodSet.Lookup agree.
+				typ := x.typ
+				if x.mode == variable {
+					// If typ is not an (unnamed) pointer or an interface,
+					// use *typ instead, because the method set of *typ
+					// includes the methods of typ.
+					// Variables are addressable, so we can always take their
+					// address.
+					if _, ok := typ.(*Pointer); !ok && !IsInterface(typ) {
+						typ = &Pointer{base: typ}
+					}
+				}
+				// If we created a synthetic pointer type above, we will throw
+				// away the method set computed here after use.
+				// TODO(gri) Method set computation should probably always compute
+				// both, the value and the pointer receiver method set and represent
+				// them in a single structure.
+				// TODO(gri) Consider also using a method set cache for the lifetime
+				// of checker once we rely on MethodSet lookup instead of individual
+				// lookup.
+				mset := NewMethodSet(typ)
+				if m := mset.Lookup(check.pkg, sel); m == nil || m.obj != obj {
+					check.dump("%s: (%s).%v -> %s", e.Pos(), typ, obj.name, m)
+					check.dump("%s\n", mset)
+					panic("method sets and lookup don't agree")
+				}
+			}
+
+			x.mode = value
+
+			// remove receiver
+			sig := *obj.typ.(*Signature)
+			sig.recv = nil
+			x.typ = &sig
+
+			check.addDeclDep(obj)
+
+		default:
+			unreachable()
+		}
+	}
+
+	// everything went well
+	x.expr = e
+	return
+
+Error:
+	x.mode = invalid
+	x.expr = e
+}
diff --git a/libgo/go/go/types/check.go b/libgo/go/go/types/check.go
new file mode 100644
index 00000000000..bb0b07415e8
--- /dev/null
+++ b/libgo/go/go/types/check.go
@@ -0,0 +1,358 @@
+// 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.
+
+// This file implements the Check function, which drives type-checking.
+
+package types
+
+import (
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+// debugging/development support
+const (
+	debug = false // leave on during development
+	trace = false // turn on for detailed type resolution traces
+)
+
+// If Strict is set, the type-checker enforces additional
+// rules not specified by the Go 1 spec, but which will
+// catch guaranteed run-time errors if the respective
+// code is executed. In other words, programs passing in
+// Strict mode are Go 1 compliant, but not all Go 1 programs
+// will pass in Strict mode. The additional rules are:
+//
+// - A type assertion x.(T) where T is an interface type
+//   is invalid if any (statically known) method that exists
+//   for both x and T have different signatures.
+//
+const strict = false
+
+// exprInfo stores information about an untyped expression.
+type exprInfo struct {
+	isLhs bool // expression is lhs operand of a shift with delayed type-check
+	mode  operandMode
+	typ   *Basic
+	val   constant.Value // constant value; or nil (if not a constant)
+}
+
+// funcInfo stores the information required for type-checking a function.
+type funcInfo struct {
+	name string    // for debugging/tracing only
+	decl *declInfo // for cycle detection
+	sig  *Signature
+	body *ast.BlockStmt
+}
+
+// A context represents the context within which an object is type-checked.
+type context struct {
+	decl          *declInfo      // package-level declaration whose init expression/function body is checked
+	scope         *Scope         // top-most scope for lookups
+	iota          constant.Value // value of iota in a constant declaration; nil otherwise
+	sig           *Signature     // function signature if inside a function; nil otherwise
+	hasLabel      bool           // set if a function makes use of labels (only ~1% of functions); unused outside functions
+	hasCallOrRecv bool           // set if an expression contains a function call or channel receive operation
+}
+
+// A Checker maintains the state of the type checker.
+// It must be created with NewChecker.
+type Checker struct {
+	// package information
+	// (initialized by NewChecker, valid for the life-time of checker)
+	conf *Config
+	fset *token.FileSet
+	pkg  *Package
+	*Info
+	objMap map[Object]*declInfo // maps package-level object to declaration info
+
+	// information collected during type-checking of a set of package files
+	// (initialized by Files, valid only for the duration of check.Files;
+	// maps and lists are allocated on demand)
+	files            []*ast.File                       // package files
+	unusedDotImports map[*Scope]map[*Package]token.Pos // positions of unused dot-imported packages for each file scope
+
+	firstErr error                 // first error encountered
+	methods  map[string][]*Func    // maps type names to associated methods
+	untyped  map[ast.Expr]exprInfo // map of expressions without final type
+	funcs    []funcInfo            // list of functions to type-check
+	delayed  []func()              // delayed checks requiring fully setup types
+
+	// context within which the current object is type-checked
+	// (valid only for the duration of type-checking a specific object)
+	context
+	pos token.Pos // if valid, identifiers are looked up as if at position pos (used by Eval)
+
+	// debugging
+	indent int // indentation for tracing
+}
+
+// addUnusedImport adds the position of a dot-imported package
+// pkg to the map of dot imports for the given file scope.
+func (check *Checker) addUnusedDotImport(scope *Scope, pkg *Package, pos token.Pos) {
+	mm := check.unusedDotImports
+	if mm == nil {
+		mm = make(map[*Scope]map[*Package]token.Pos)
+		check.unusedDotImports = mm
+	}
+	m := mm[scope]
+	if m == nil {
+		m = make(map[*Package]token.Pos)
+		mm[scope] = m
+	}
+	m[pkg] = pos
+}
+
+// addDeclDep adds the dependency edge (check.decl -> to) if check.decl exists
+func (check *Checker) addDeclDep(to Object) {
+	from := check.decl
+	if from == nil {
+		return // not in a package-level init expression
+	}
+	if _, found := check.objMap[to]; !found {
+		return // to is not a package-level object
+	}
+	from.addDep(to)
+}
+
+func (check *Checker) assocMethod(tname string, meth *Func) {
+	m := check.methods
+	if m == nil {
+		m = make(map[string][]*Func)
+		check.methods = m
+	}
+	m[tname] = append(m[tname], meth)
+}
+
+func (check *Checker) rememberUntyped(e ast.Expr, lhs bool, mode operandMode, typ *Basic, val constant.Value) {
+	m := check.untyped
+	if m == nil {
+		m = make(map[ast.Expr]exprInfo)
+		check.untyped = m
+	}
+	m[e] = exprInfo{lhs, mode, typ, val}
+}
+
+func (check *Checker) later(name string, decl *declInfo, sig *Signature, body *ast.BlockStmt) {
+	check.funcs = append(check.funcs, funcInfo{name, decl, sig, body})
+}
+
+func (check *Checker) delay(f func()) {
+	check.delayed = append(check.delayed, f)
+}
+
+// NewChecker returns a new Checker instance for a given package.
+// Package files may be added incrementally via checker.Files.
+func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker {
+	// make sure we have a configuration
+	if conf == nil {
+		conf = new(Config)
+	}
+
+	// make sure we have an info struct
+	if info == nil {
+		info = new(Info)
+	}
+
+	return &Checker{
+		conf:   conf,
+		fset:   fset,
+		pkg:    pkg,
+		Info:   info,
+		objMap: make(map[Object]*declInfo),
+	}
+}
+
+// initFiles initializes the files-specific portion of checker.
+// The provided files must all belong to the same package.
+func (check *Checker) initFiles(files []*ast.File) {
+	// start with a clean slate (check.Files may be called multiple times)
+	check.files = nil
+	check.unusedDotImports = nil
+
+	check.firstErr = nil
+	check.methods = nil
+	check.untyped = nil
+	check.funcs = nil
+	check.delayed = nil
+
+	// determine package name and collect valid files
+	pkg := check.pkg
+	for _, file := range files {
+		switch name := file.Name.Name; pkg.name {
+		case "":
+			if name != "_" {
+				pkg.name = name
+			} else {
+				check.errorf(file.Name.Pos(), "invalid package name _")
+			}
+			fallthrough
+
+		case name:
+			check.files = append(check.files, file)
+
+		default:
+			check.errorf(file.Package, "package %s; expected %s", name, pkg.name)
+			// ignore this file
+		}
+	}
+}
+
+// A bailout panic is used for early termination.
+type bailout struct{}
+
+func (check *Checker) handleBailout(err *error) {
+	switch p := recover().(type) {
+	case nil, bailout:
+		// normal return or early exit
+		*err = check.firstErr
+	default:
+		// re-panic
+		panic(p)
+	}
+}
+
+// Files checks the provided files as part of the checker's package.
+func (check *Checker) Files(files []*ast.File) (err error) {
+	defer check.handleBailout(&err)
+
+	check.initFiles(files)
+
+	check.collectObjects()
+
+	check.packageObjects(check.resolveOrder())
+
+	check.functionBodies()
+
+	check.initOrder()
+
+	if !check.conf.DisableUnusedImportCheck {
+		check.unusedImports()
+	}
+
+	// perform delayed checks
+	for _, f := range check.delayed {
+		f()
+	}
+
+	check.recordUntyped()
+
+	check.pkg.complete = true
+	return
+}
+
+func (check *Checker) recordUntyped() {
+	if !debug && check.Types == nil {
+		return // nothing to do
+	}
+
+	for x, info := range check.untyped {
+		if debug && isTyped(info.typ) {
+			check.dump("%s: %s (type %s) is typed", x.Pos(), x, info.typ)
+			unreachable()
+		}
+		check.recordTypeAndValue(x, info.mode, info.typ, info.val)
+	}
+}
+
+func (check *Checker) recordTypeAndValue(x ast.Expr, mode operandMode, typ Type, val constant.Value) {
+	assert(x != nil)
+	assert(typ != nil)
+	if mode == invalid {
+		return // omit
+	}
+	assert(typ != nil)
+	if mode == constant_ {
+		assert(val != nil)
+		assert(typ == Typ[Invalid] || isConstType(typ))
+	}
+	if m := check.Types; m != nil {
+		m[x] = TypeAndValue{mode, typ, val}
+	}
+}
+
+func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
+	// f must be a (possibly parenthesized) identifier denoting a built-in
+	// (built-ins in package unsafe always produce a constant result and
+	// we don't record their signatures, so we don't see qualified idents
+	// here): record the signature for f and possible children.
+	for {
+		check.recordTypeAndValue(f, builtin, sig, nil)
+		switch p := f.(type) {
+		case *ast.Ident:
+			return // we're done
+		case *ast.ParenExpr:
+			f = p.X
+		default:
+			unreachable()
+		}
+	}
+}
+
+func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
+	assert(x != nil)
+	if a[0] == nil || a[1] == nil {
+		return
+	}
+	assert(isTyped(a[0]) && isTyped(a[1]) && isBoolean(a[1]))
+	if m := check.Types; m != nil {
+		for {
+			tv := m[x]
+			assert(tv.Type != nil) // should have been recorded already
+			pos := x.Pos()
+			tv.Type = NewTuple(
+				NewVar(pos, check.pkg, "", a[0]),
+				NewVar(pos, check.pkg, "", a[1]),
+			)
+			m[x] = tv
+			// if x is a parenthesized expression (p.X), update p.X
+			p, _ := x.(*ast.ParenExpr)
+			if p == nil {
+				break
+			}
+			x = p.X
+		}
+	}
+}
+
+func (check *Checker) recordDef(id *ast.Ident, obj Object) {
+	assert(id != nil)
+	if m := check.Defs; m != nil {
+		m[id] = obj
+	}
+}
+
+func (check *Checker) recordUse(id *ast.Ident, obj Object) {
+	assert(id != nil)
+	assert(obj != nil)
+	if m := check.Uses; m != nil {
+		m[id] = obj
+	}
+}
+
+func (check *Checker) recordImplicit(node ast.Node, obj Object) {
+	assert(node != nil)
+	assert(obj != nil)
+	if m := check.Implicits; m != nil {
+		m[node] = obj
+	}
+}
+
+func (check *Checker) recordSelection(x *ast.SelectorExpr, kind SelectionKind, recv Type, obj Object, index []int, indirect bool) {
+	assert(obj != nil && (recv == nil || len(index) > 0))
+	check.recordUse(x.Sel, obj)
+	// TODO(gri) Should we also call recordTypeAndValue?
+	if m := check.Selections; m != nil {
+		m[x] = &Selection{kind, recv, obj, index, indirect}
+	}
+}
+
+func (check *Checker) recordScope(node ast.Node, scope *Scope) {
+	assert(node != nil)
+	assert(scope != nil)
+	if m := check.Scopes; m != nil {
+		m[node] = scope
+	}
+}
diff --git a/libgo/go/go/types/check_test.go b/libgo/go/go/types/check_test.go
new file mode 100644
index 00000000000..5e34c65b636
--- /dev/null
+++ b/libgo/go/go/types/check_test.go
@@ -0,0 +1,298 @@
+// 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.
+
+// This file implements a typechecker test harness. The packages specified
+// in tests are typechecked. Error messages reported by the typechecker are
+// compared against the error messages expected in the test files.
+//
+// Expected errors are indicated in the test files by putting a comment
+// of the form /* ERROR "rx" */ immediately following an offending token.
+// The harness will verify that an error matching the regular expression
+// rx is reported at that source position. Consecutive comments may be
+// used to indicate multiple errors for the same token position.
+//
+// For instance, the following test file indicates that a "not declared"
+// error should be reported for the undeclared variable x:
+//
+//	package p
+//	func f() {
+//		_ = x /* ERROR "not declared" */ + 1
+//	}
+
+// TODO(gri) Also collect strict mode errors of the form /* STRICT ... */
+//           and test against strict mode.
+
+package types_test
+
+import (
+	"flag"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"internal/testenv"
+	"io/ioutil"
+	"regexp"
+	"strings"
+	"testing"
+
+	. "go/types"
+)
+
+var (
+	listErrors = flag.Bool("list", false, "list errors")
+	testFiles  = flag.String("files", "", "space-separated list of test files")
+)
+
+// The test filenames do not end in .go so that they are invisible
+// to gofmt since they contain comments that must not change their
+// positions relative to surrounding tokens.
+
+// Each tests entry is list of files belonging to the same package.
+var tests = [][]string{
+	{"testdata/errors.src"},
+	{"testdata/importdecl0a.src", "testdata/importdecl0b.src"},
+	{"testdata/importdecl1a.src", "testdata/importdecl1b.src"},
+	{"testdata/cycles.src"},
+	{"testdata/cycles1.src"},
+	{"testdata/cycles2.src"},
+	{"testdata/cycles3.src"},
+	{"testdata/cycles4.src"},
+	{"testdata/init0.src"},
+	{"testdata/init1.src"},
+	{"testdata/init2.src"},
+	{"testdata/decls0.src"},
+	{"testdata/decls1.src"},
+	{"testdata/decls2a.src", "testdata/decls2b.src"},
+	{"testdata/decls3.src"},
+	{"testdata/const0.src"},
+	{"testdata/const1.src"},
+	{"testdata/constdecl.src"},
+	{"testdata/vardecl.src"},
+	{"testdata/expr0.src"},
+	{"testdata/expr1.src"},
+	{"testdata/expr2.src"},
+	{"testdata/expr3.src"},
+	{"testdata/methodsets.src"},
+	{"testdata/shifts.src"},
+	{"testdata/builtins.src"},
+	{"testdata/conversions.src"},
+	{"testdata/stmt0.src"},
+	{"testdata/stmt1.src"},
+	{"testdata/gotos.src"},
+	{"testdata/labels.src"},
+	{"testdata/issues.src"},
+	{"testdata/blank.src"},
+}
+
+var fset = token.NewFileSet()
+
+// Positioned errors are of the form filename:line:column: message .
+var posMsgRx = regexp.MustCompile(`^(.*:[0-9]+:[0-9]+): *(.*)`)
+
+// splitError splits an error's error message into a position string
+// and the actual error message. If there's no position information,
+// pos is the empty string, and msg is the entire error message.
+//
+func splitError(err error) (pos, msg string) {
+	msg = err.Error()
+	if m := posMsgRx.FindStringSubmatch(msg); len(m) == 3 {
+		pos = m[1]
+		msg = m[2]
+	}
+	return
+}
+
+func parseFiles(t *testing.T, filenames []string) ([]*ast.File, []error) {
+	var files []*ast.File
+	var errlist []error
+	for _, filename := range filenames {
+		file, err := parser.ParseFile(fset, filename, nil, parser.AllErrors)
+		if file == nil {
+			t.Fatalf("%s: %s", filename, err)
+		}
+		files = append(files, file)
+		if err != nil {
+			if list, _ := err.(scanner.ErrorList); len(list) > 0 {
+				for _, err := range list {
+					errlist = append(errlist, err)
+				}
+			} else {
+				errlist = append(errlist, err)
+			}
+		}
+	}
+	return files, errlist
+}
+
+// ERROR comments must start with text `ERROR "rx"` or `ERROR rx` where
+// rx is a regular expression that matches the expected error message.
+// Space around "rx" or rx is ignored. Use the form `ERROR HERE "rx"`
+// for error messages that are located immediately after rather than
+// at a token's position.
+//
+var errRx = regexp.MustCompile(`^ *ERROR *(HERE)? *"?([^"]*)"?`)
+
+// errMap collects the regular expressions of ERROR comments found
+// in files and returns them as a map of error positions to error messages.
+//
+func errMap(t *testing.T, testname string, files []*ast.File) map[string][]string {
+	// map of position strings to lists of error message patterns
+	errmap := make(map[string][]string)
+
+	for _, file := range files {
+		filename := fset.Position(file.Package).Filename
+		src, err := ioutil.ReadFile(filename)
+		if err != nil {
+			t.Fatalf("%s: could not read %s", testname, filename)
+		}
+
+		var s scanner.Scanner
+		s.Init(fset.AddFile(filename, -1, len(src)), src, nil, scanner.ScanComments)
+		var prev token.Pos // position of last non-comment, non-semicolon token
+		var here token.Pos // position immediately after the token at position prev
+
+	scanFile:
+		for {
+			pos, tok, lit := s.Scan()
+			switch tok {
+			case token.EOF:
+				break scanFile
+			case token.COMMENT:
+				if lit[1] == '*' {
+					lit = lit[:len(lit)-2] // strip trailing */
+				}
+				if s := errRx.FindStringSubmatch(lit[2:]); len(s) == 3 {
+					pos := prev
+					if s[1] == "HERE" {
+						pos = here
+					}
+					p := fset.Position(pos).String()
+					errmap[p] = append(errmap[p], strings.TrimSpace(s[2]))
+				}
+			case token.SEMICOLON:
+				// ignore automatically inserted semicolon
+				if lit == "\n" {
+					continue scanFile
+				}
+				fallthrough
+			default:
+				prev = pos
+				var l int // token length
+				if tok.IsLiteral() {
+					l = len(lit)
+				} else {
+					l = len(tok.String())
+				}
+				here = prev + token.Pos(l)
+			}
+		}
+	}
+
+	return errmap
+}
+
+func eliminate(t *testing.T, errmap map[string][]string, errlist []error) {
+	for _, err := range errlist {
+		pos, gotMsg := splitError(err)
+		list := errmap[pos]
+		index := -1 // list index of matching message, if any
+		// we expect one of the messages in list to match the error at pos
+		for i, wantRx := range list {
+			rx, err := regexp.Compile(wantRx)
+			if err != nil {
+				t.Errorf("%s: %v", pos, err)
+				continue
+			}
+			if rx.MatchString(gotMsg) {
+				index = i
+				break
+			}
+		}
+		if index >= 0 {
+			// eliminate from list
+			if n := len(list) - 1; n > 0 {
+				// not the last entry - swap in last element and shorten list by 1
+				list[index] = list[n]
+				errmap[pos] = list[:n]
+			} else {
+				// last entry - remove list from map
+				delete(errmap, pos)
+			}
+		} else {
+			t.Errorf("%s: no error expected: %q", pos, gotMsg)
+		}
+	}
+}
+
+func checkFiles(t *testing.T, testfiles []string) {
+	// parse files and collect parser errors
+	files, errlist := parseFiles(t, testfiles)
+
+	pkgName := "<no package>"
+	if len(files) > 0 {
+		pkgName = files[0].Name.Name
+	}
+
+	if *listErrors && len(errlist) > 0 {
+		t.Errorf("--- %s:", pkgName)
+		for _, err := range errlist {
+			t.Error(err)
+		}
+	}
+
+	// typecheck and collect typechecker errors
+	var conf Config
+	conf.Importer = importer.Default()
+	conf.Error = func(err error) {
+		if *listErrors {
+			t.Error(err)
+			return
+		}
+		// Ignore secondary error messages starting with "\t";
+		// they are clarifying messages for a primary error.
+		if !strings.Contains(err.Error(), ": \t") {
+			errlist = append(errlist, err)
+		}
+	}
+	conf.Check(pkgName, fset, files, nil)
+
+	if *listErrors {
+		return
+	}
+
+	// match and eliminate errors;
+	// we are expecting the following errors
+	errmap := errMap(t, pkgName, files)
+	eliminate(t, errmap, errlist)
+
+	// there should be no expected errors left
+	if len(errmap) > 0 {
+		t.Errorf("--- %s: %d source positions with expected (but not reported) errors:", pkgName, len(errmap))
+		for pos, list := range errmap {
+			for _, rx := range list {
+				t.Errorf("%s: %q", pos, rx)
+			}
+		}
+	}
+}
+
+func TestCheck(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	// Declare builtins for testing.
+	DefPredeclaredTestFuncs()
+
+	// If explicit test files are specified, only check those.
+	if files := *testFiles; files != "" {
+		checkFiles(t, strings.Split(files, " "))
+		return
+	}
+
+	// Otherwise, run all the tests.
+	for _, files := range tests {
+		checkFiles(t, files)
+	}
+}
diff --git a/libgo/go/go/types/conversions.go b/libgo/go/go/types/conversions.go
new file mode 100644
index 00000000000..74826ce9345
--- /dev/null
+++ b/libgo/go/go/types/conversions.go
@@ -0,0 +1,146 @@
+// 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.
+
+// This file implements typechecking of conversions.
+
+package types
+
+import "go/constant"
+
+// Conversion type-checks the conversion T(x).
+// The result is in x.
+func (check *Checker) conversion(x *operand, T Type) {
+	constArg := x.mode == constant_
+
+	var ok bool
+	switch {
+	case constArg && isConstType(T):
+		// constant conversion
+		switch t := T.Underlying().(*Basic); {
+		case representableConst(x.val, check.conf, t.kind, &x.val):
+			ok = true
+		case isInteger(x.typ) && isString(t):
+			codepoint := int64(-1)
+			if i, ok := constant.Int64Val(x.val); ok {
+				codepoint = i
+			}
+			// If codepoint < 0 the absolute value is too large (or unknown) for
+			// conversion. This is the same as converting any other out-of-range
+			// value - let string(codepoint) do the work.
+			x.val = constant.MakeString(string(codepoint))
+			ok = true
+		}
+	case x.convertibleTo(check.conf, T):
+		// non-constant conversion
+		x.mode = value
+		ok = true
+	}
+
+	if !ok {
+		check.errorf(x.pos(), "cannot convert %s to %s", x, T)
+		x.mode = invalid
+		return
+	}
+
+	// The conversion argument types are final. For untyped values the
+	// conversion provides the type, per the spec: "A constant may be
+	// given a type explicitly by a constant declaration or conversion,...".
+	final := x.typ
+	if isUntyped(x.typ) {
+		final = T
+		// - For conversions to interfaces, use the argument's default type.
+		// - For conversions of untyped constants to non-constant types, also
+		//   use the default type (e.g., []byte("foo") should report string
+		//   not []byte as type for the constant "foo").
+		// - Keep untyped nil for untyped nil arguments.
+		if IsInterface(T) || constArg && !isConstType(T) {
+			final = defaultType(x.typ)
+		}
+		check.updateExprType(x.expr, final, true)
+	}
+
+	x.typ = T
+}
+
+func (x *operand) convertibleTo(conf *Config, T Type) bool {
+	// "x is assignable to T"
+	if x.assignableTo(conf, T) {
+		return true
+	}
+
+	// "x's type and T have identical underlying types"
+	V := x.typ
+	Vu := V.Underlying()
+	Tu := T.Underlying()
+	if Identical(Vu, Tu) {
+		return true
+	}
+
+	// "x's type and T are unnamed pointer types and their pointer base types have identical underlying types"
+	if V, ok := V.(*Pointer); ok {
+		if T, ok := T.(*Pointer); ok {
+			if Identical(V.base.Underlying(), T.base.Underlying()) {
+				return true
+			}
+		}
+	}
+
+	// "x's type and T are both integer or floating point types"
+	if (isInteger(V) || isFloat(V)) && (isInteger(T) || isFloat(T)) {
+		return true
+	}
+
+	// "x's type and T are both complex types"
+	if isComplex(V) && isComplex(T) {
+		return true
+	}
+
+	// "x is an integer or a slice of bytes or runes and T is a string type"
+	if (isInteger(V) || isBytesOrRunes(Vu)) && isString(T) {
+		return true
+	}
+
+	// "x is a string and T is a slice of bytes or runes"
+	if isString(V) && isBytesOrRunes(Tu) {
+		return true
+	}
+
+	// package unsafe:
+	// "any pointer or value of underlying type uintptr can be converted into a unsafe.Pointer"
+	if (isPointer(Vu) || isUintptr(Vu)) && isUnsafePointer(T) {
+		return true
+	}
+	// "and vice versa"
+	if isUnsafePointer(V) && (isPointer(Tu) || isUintptr(Tu)) {
+		return true
+	}
+
+	return false
+}
+
+func isUintptr(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.kind == Uintptr
+}
+
+func isUnsafePointer(typ Type) bool {
+	// TODO(gri): Is this (typ.Underlying() instead of just typ) correct?
+	//            The spec does not say so, but gc claims it is. See also
+	//            issue 6326.
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.kind == UnsafePointer
+}
+
+func isPointer(typ Type) bool {
+	_, ok := typ.Underlying().(*Pointer)
+	return ok
+}
+
+func isBytesOrRunes(typ Type) bool {
+	if s, ok := typ.(*Slice); ok {
+		t, ok := s.elem.Underlying().(*Basic)
+		return ok && (t.kind == Byte || t.kind == Rune)
+	}
+	return false
+}
diff --git a/libgo/go/go/types/decl.go b/libgo/go/go/types/decl.go
new file mode 100644
index 00000000000..8e9e5f36de4
--- /dev/null
+++ b/libgo/go/go/types/decl.go
@@ -0,0 +1,430 @@
+// Copyright 2014 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 types
+
+import (
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+func (check *Checker) reportAltDecl(obj Object) {
+	if pos := obj.Pos(); pos.IsValid() {
+		// We use "other" rather than "previous" here because
+		// the first declaration seen may not be textually
+		// earlier in the source.
+		check.errorf(pos, "\tother declaration of %s", obj.Name()) // secondary error, \t indented
+	}
+}
+
+func (check *Checker) declare(scope *Scope, id *ast.Ident, obj Object, pos token.Pos) {
+	// spec: "The blank identifier, represented by the underscore
+	// character _, may be used in a declaration like any other
+	// identifier but the declaration does not introduce a new
+	// binding."
+	if obj.Name() != "_" {
+		if alt := scope.Insert(obj); alt != nil {
+			check.errorf(obj.Pos(), "%s redeclared in this block", obj.Name())
+			check.reportAltDecl(alt)
+			return
+		}
+		obj.setScopePos(pos)
+	}
+	if id != nil {
+		check.recordDef(id, obj)
+	}
+}
+
+// objDecl type-checks the declaration of obj in its respective (file) context.
+// See check.typ for the details on def and path.
+func (check *Checker) objDecl(obj Object, def *Named, path []*TypeName) {
+	if obj.Type() != nil {
+		return // already checked - nothing to do
+	}
+
+	if trace {
+		check.trace(obj.Pos(), "-- declaring %s", obj.Name())
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(obj.Pos(), "=> %s", obj)
+		}()
+	}
+
+	d := check.objMap[obj]
+	if d == nil {
+		check.dump("%s: %s should have been declared", obj.Pos(), obj.Name())
+		unreachable()
+	}
+
+	// save/restore current context and setup object context
+	defer func(ctxt context) {
+		check.context = ctxt
+	}(check.context)
+	check.context = context{
+		scope: d.file,
+	}
+
+	// Const and var declarations must not have initialization
+	// cycles. We track them by remembering the current declaration
+	// in check.decl. Initialization expressions depending on other
+	// consts, vars, or functions, add dependencies to the current
+	// check.decl.
+	switch obj := obj.(type) {
+	case *Const:
+		check.decl = d // new package-level const decl
+		check.constDecl(obj, d.typ, d.init)
+	case *Var:
+		check.decl = d // new package-level var decl
+		check.varDecl(obj, d.lhs, d.typ, d.init)
+	case *TypeName:
+		// invalid recursive types are detected via path
+		check.typeDecl(obj, d.typ, def, path)
+	case *Func:
+		// functions may be recursive - no need to track dependencies
+		check.funcDecl(obj, d)
+	default:
+		unreachable()
+	}
+}
+
+func (check *Checker) constDecl(obj *Const, typ, init ast.Expr) {
+	assert(obj.typ == nil)
+
+	if obj.visited {
+		obj.typ = Typ[Invalid]
+		return
+	}
+	obj.visited = true
+
+	// use the correct value of iota
+	assert(check.iota == nil)
+	check.iota = obj.val
+	defer func() { check.iota = nil }()
+
+	// provide valid constant value under all circumstances
+	obj.val = constant.MakeUnknown()
+
+	// determine type, if any
+	if typ != nil {
+		t := check.typ(typ)
+		if !isConstType(t) {
+			check.errorf(typ.Pos(), "invalid constant type %s", t)
+			obj.typ = Typ[Invalid]
+			return
+		}
+		obj.typ = t
+	}
+
+	// check initialization
+	var x operand
+	if init != nil {
+		check.expr(&x, init)
+	}
+	check.initConst(obj, &x)
+}
+
+func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
+	assert(obj.typ == nil)
+
+	if obj.visited {
+		obj.typ = Typ[Invalid]
+		return
+	}
+	obj.visited = true
+
+	// var declarations cannot use iota
+	assert(check.iota == nil)
+
+	// determine type, if any
+	if typ != nil {
+		obj.typ = check.typ(typ)
+	}
+
+	// check initialization
+	if init == nil {
+		if typ == nil {
+			// error reported before by arityMatch
+			obj.typ = Typ[Invalid]
+		}
+		return
+	}
+
+	if lhs == nil || len(lhs) == 1 {
+		assert(lhs == nil || lhs[0] == obj)
+		var x operand
+		check.expr(&x, init)
+		check.initVar(obj, &x, false)
+		return
+	}
+
+	if debug {
+		// obj must be one of lhs
+		found := false
+		for _, lhs := range lhs {
+			if obj == lhs {
+				found = true
+				break
+			}
+		}
+		if !found {
+			panic("inconsistent lhs")
+		}
+	}
+	check.initVars(lhs, []ast.Expr{init}, token.NoPos)
+}
+
+// underlying returns the underlying type of typ; possibly by following
+// forward chains of named types. Such chains only exist while named types
+// are incomplete.
+func underlying(typ Type) Type {
+	for {
+		n, _ := typ.(*Named)
+		if n == nil {
+			break
+		}
+		typ = n.underlying
+	}
+	return typ
+}
+
+func (n *Named) setUnderlying(typ Type) {
+	if n != nil {
+		n.underlying = typ
+	}
+}
+
+func (check *Checker) typeDecl(obj *TypeName, typ ast.Expr, def *Named, path []*TypeName) {
+	assert(obj.typ == nil)
+
+	// type declarations cannot use iota
+	assert(check.iota == nil)
+
+	named := &Named{obj: obj}
+	def.setUnderlying(named)
+	obj.typ = named // make sure recursive type declarations terminate
+
+	// determine underlying type of named
+	check.typExpr(typ, named, append(path, obj))
+
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain (they always end in an unnamed type).
+	named.underlying = underlying(named.underlying)
+
+	// check and add associated methods
+	// TODO(gri) It's easy to create pathological cases where the
+	// current approach is incorrect: In general we need to know
+	// and add all methods _before_ type-checking the type.
+	// See https://play.golang.org/p/WMpE0q2wK8
+	check.addMethodDecls(obj)
+}
+
+func (check *Checker) addMethodDecls(obj *TypeName) {
+	// get associated methods
+	methods := check.methods[obj.name]
+	if len(methods) == 0 {
+		return // no methods
+	}
+	delete(check.methods, obj.name)
+
+	// use an objset to check for name conflicts
+	var mset objset
+
+	// spec: "If the base type is a struct type, the non-blank method
+	// and field names must be distinct."
+	base := obj.typ.(*Named)
+	if t, _ := base.underlying.(*Struct); t != nil {
+		for _, fld := range t.fields {
+			if fld.name != "_" {
+				assert(mset.insert(fld) == nil)
+			}
+		}
+	}
+
+	// Checker.Files may be called multiple times; additional package files
+	// may add methods to already type-checked types. Add pre-existing methods
+	// so that we can detect redeclarations.
+	for _, m := range base.methods {
+		assert(m.name != "_")
+		assert(mset.insert(m) == nil)
+	}
+
+	// type-check methods
+	for _, m := range methods {
+		// spec: "For a base type, the non-blank names of methods bound
+		// to it must be unique."
+		if m.name != "_" {
+			if alt := mset.insert(m); alt != nil {
+				switch alt.(type) {
+				case *Var:
+					check.errorf(m.pos, "field and method with the same name %s", m.name)
+				case *Func:
+					check.errorf(m.pos, "method %s already declared for %s", m.name, base)
+				default:
+					unreachable()
+				}
+				check.reportAltDecl(alt)
+				continue
+			}
+		}
+		check.objDecl(m, nil, nil)
+		// methods with blank _ names cannot be found - don't keep them
+		if m.name != "_" {
+			base.methods = append(base.methods, m)
+		}
+	}
+}
+
+func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
+	assert(obj.typ == nil)
+
+	// func declarations cannot use iota
+	assert(check.iota == nil)
+
+	sig := new(Signature)
+	obj.typ = sig // guard against cycles
+	fdecl := decl.fdecl
+	check.funcType(sig, fdecl.Recv, fdecl.Type)
+	if sig.recv == nil && obj.name == "init" && (sig.params.Len() > 0 || sig.results.Len() > 0) {
+		check.errorf(fdecl.Pos(), "func init must have no arguments and no return values")
+		// ok to continue
+	}
+
+	// function body must be type-checked after global declarations
+	// (functions implemented elsewhere have no body)
+	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
+		check.later(obj.name, decl, sig, fdecl.Body)
+	}
+}
+
+func (check *Checker) declStmt(decl ast.Decl) {
+	pkg := check.pkg
+
+	switch d := decl.(type) {
+	case *ast.BadDecl:
+		// ignore
+
+	case *ast.GenDecl:
+		var last *ast.ValueSpec // last ValueSpec with type or init exprs seen
+		for iota, spec := range d.Specs {
+			switch s := spec.(type) {
+			case *ast.ValueSpec:
+				switch d.Tok {
+				case token.CONST:
+					// determine which init exprs to use
+					switch {
+					case s.Type != nil || len(s.Values) > 0:
+						last = s
+					case last == nil:
+						last = new(ast.ValueSpec) // make sure last exists
+					}
+
+					// declare all constants
+					lhs := make([]*Const, len(s.Names))
+					for i, name := range s.Names {
+						obj := NewConst(name.Pos(), pkg, name.Name, nil, constant.MakeInt64(int64(iota)))
+						lhs[i] = obj
+
+						var init ast.Expr
+						if i < len(last.Values) {
+							init = last.Values[i]
+						}
+
+						check.constDecl(obj, last.Type, init)
+					}
+
+					check.arityMatch(s, last)
+
+					// spec: "The scope of a constant or variable identifier declared
+					// inside a function begins at the end of the ConstSpec or VarSpec
+					// (ShortVarDecl for short variable declarations) and ends at the
+					// end of the innermost containing block."
+					scopePos := s.End()
+					for i, name := range s.Names {
+						check.declare(check.scope, name, lhs[i], scopePos)
+					}
+
+				case token.VAR:
+					lhs0 := make([]*Var, len(s.Names))
+					for i, name := range s.Names {
+						lhs0[i] = NewVar(name.Pos(), pkg, name.Name, nil)
+					}
+
+					// initialize all variables
+					for i, obj := range lhs0 {
+						var lhs []*Var
+						var init ast.Expr
+						switch len(s.Values) {
+						case len(s.Names):
+							// lhs and rhs match
+							init = s.Values[i]
+						case 1:
+							// rhs is expected to be a multi-valued expression
+							lhs = lhs0
+							init = s.Values[0]
+						default:
+							if i < len(s.Values) {
+								init = s.Values[i]
+							}
+						}
+						check.varDecl(obj, lhs, s.Type, init)
+						if len(s.Values) == 1 {
+							// If we have a single lhs variable we are done either way.
+							// If we have a single rhs expression, it must be a multi-
+							// valued expression, in which case handling the first lhs
+							// variable will cause all lhs variables to have a type
+							// assigned, and we are done as well.
+							if debug {
+								for _, obj := range lhs0 {
+									assert(obj.typ != nil)
+								}
+							}
+							break
+						}
+					}
+
+					check.arityMatch(s, nil)
+
+					// declare all variables
+					// (only at this point are the variable scopes (parents) set)
+					scopePos := s.End() // see constant declarations
+					for i, name := range s.Names {
+						// see constant declarations
+						check.declare(check.scope, name, lhs0[i], scopePos)
+					}
+
+				default:
+					check.invalidAST(s.Pos(), "invalid token %s", d.Tok)
+				}
+
+			case *ast.TypeSpec:
+				obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Name, nil)
+				// spec: "The scope of a type identifier declared inside a function
+				// begins at the identifier in the TypeSpec and ends at the end of
+				// the innermost containing block."
+				scopePos := s.Name.Pos()
+				check.declare(check.scope, s.Name, obj, scopePos)
+				check.typeDecl(obj, s.Type, nil, nil)
+
+			default:
+				check.invalidAST(s.Pos(), "const, type, or var declaration expected")
+			}
+		}
+
+	default:
+		check.invalidAST(d.Pos(), "unknown ast.Decl node %T", d)
+	}
+}
diff --git a/libgo/go/go/types/errors.go b/libgo/go/go/types/errors.go
new file mode 100644
index 00000000000..0c0049b1f3e
--- /dev/null
+++ b/libgo/go/go/types/errors.go
@@ -0,0 +1,103 @@
+// 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.
+
+// This file implements various error reporters.
+
+package types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"strings"
+)
+
+func assert(p bool) {
+	if !p {
+		panic("assertion failed")
+	}
+}
+
+func unreachable() {
+	panic("unreachable")
+}
+
+func (check *Checker) qualifier(pkg *Package) string {
+	if pkg != check.pkg {
+		return pkg.path
+	}
+	return ""
+}
+
+func (check *Checker) sprintf(format string, args ...interface{}) string {
+	for i, arg := range args {
+		switch a := arg.(type) {
+		case nil:
+			arg = "<nil>"
+		case operand:
+			panic("internal error: should always pass *operand")
+		case *operand:
+			arg = operandString(a, check.qualifier)
+		case token.Pos:
+			arg = check.fset.Position(a).String()
+		case ast.Expr:
+			arg = ExprString(a)
+		case Object:
+			arg = ObjectString(a, check.qualifier)
+		case Type:
+			arg = TypeString(a, check.qualifier)
+		}
+		args[i] = arg
+	}
+	return fmt.Sprintf(format, args...)
+}
+
+func (check *Checker) trace(pos token.Pos, format string, args ...interface{}) {
+	fmt.Printf("%s:\t%s%s\n",
+		check.fset.Position(pos),
+		strings.Repeat(".  ", check.indent),
+		check.sprintf(format, args...),
+	)
+}
+
+// dump is only needed for debugging
+func (check *Checker) dump(format string, args ...interface{}) {
+	fmt.Println(check.sprintf(format, args...))
+}
+
+func (check *Checker) err(pos token.Pos, msg string, soft bool) {
+	err := Error{check.fset, pos, msg, soft}
+	if check.firstErr == nil {
+		check.firstErr = err
+	}
+	f := check.conf.Error
+	if f == nil {
+		panic(bailout{}) // report only first error
+	}
+	f(err)
+}
+
+func (check *Checker) error(pos token.Pos, msg string) {
+	check.err(pos, msg, false)
+}
+
+func (check *Checker) errorf(pos token.Pos, format string, args ...interface{}) {
+	check.err(pos, check.sprintf(format, args...), false)
+}
+
+func (check *Checker) softErrorf(pos token.Pos, format string, args ...interface{}) {
+	check.err(pos, check.sprintf(format, args...), true)
+}
+
+func (check *Checker) invalidAST(pos token.Pos, format string, args ...interface{}) {
+	check.errorf(pos, "invalid AST: "+format, args...)
+}
+
+func (check *Checker) invalidArg(pos token.Pos, format string, args ...interface{}) {
+	check.errorf(pos, "invalid argument: "+format, args...)
+}
+
+func (check *Checker) invalidOp(pos token.Pos, format string, args ...interface{}) {
+	check.errorf(pos, "invalid operation: "+format, args...)
+}
diff --git a/libgo/go/go/types/eval.go b/libgo/go/go/types/eval.go
new file mode 100644
index 00000000000..7b42ff1a9d0
--- /dev/null
+++ b/libgo/go/go/types/eval.go
@@ -0,0 +1,83 @@
+// Copyright 2013 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 types
+
+import (
+	"fmt"
+	"go/parser"
+	"go/token"
+)
+
+// Eval returns the type and, if constant, the value for the
+// expression expr, evaluated at position pos of package pkg,
+// which must have been derived from type-checking an AST with
+// complete position information relative to the provided file
+// set.
+//
+// If the expression contains function literals, their bodies
+// are ignored (i.e., the bodies are not type-checked).
+//
+// If pkg == nil, the Universe scope is used and the provided
+// position pos is ignored. If pkg != nil, and pos is invalid,
+// the package scope is used. Otherwise, pos must belong to the
+// package.
+//
+// An error is returned if pos is not within the package or
+// if the node cannot be evaluated.
+//
+// Note: Eval should not be used instead of running Check to compute
+// types and values, but in addition to Check. Eval will re-evaluate
+// its argument each time, and it also does not know about the context
+// in which an expression is used (e.g., an assignment). Thus, top-
+// level untyped constants will return an untyped type rather then the
+// respective context-specific type.
+//
+func Eval(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (tv TypeAndValue, err error) {
+	// determine scope
+	var scope *Scope
+	if pkg == nil {
+		scope = Universe
+		pos = token.NoPos
+	} else if !pos.IsValid() {
+		scope = pkg.scope
+	} else {
+		// The package scope extent (position information) may be
+		// incorrect (files spread accross a wide range of fset
+		// positions) - ignore it and just consider its children
+		// (file scopes).
+		for _, fscope := range pkg.scope.children {
+			if scope = fscope.Innermost(pos); scope != nil {
+				break
+			}
+		}
+		if scope == nil || debug {
+			s := scope
+			for s != nil && s != pkg.scope {
+				s = s.parent
+			}
+			// s == nil || s == pkg.scope
+			if s == nil {
+				return TypeAndValue{}, fmt.Errorf("no position %s found in package %s", fset.Position(pos), pkg.name)
+			}
+		}
+	}
+
+	// parse expressions
+	node, err := parser.ParseExprFrom(fset, "eval", expr, 0)
+	if err != nil {
+		return TypeAndValue{}, err
+	}
+
+	// initialize checker
+	check := NewChecker(nil, fset, pkg, nil)
+	check.scope = scope
+	check.pos = pos
+	defer check.handleBailout(&err)
+
+	// evaluate node
+	var x operand
+	check.rawExpr(&x, node, nil)
+	return TypeAndValue{x.mode, x.typ, x.val}, err
+}
diff --git a/libgo/go/go/types/eval_test.go b/libgo/go/go/types/eval_test.go
new file mode 100644
index 00000000000..7e0be43e723
--- /dev/null
+++ b/libgo/go/go/types/eval_test.go
@@ -0,0 +1,188 @@
+// Copyright 2013 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.
+
+// This file contains tests for Eval.
+
+package types_test
+
+import (
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"internal/testenv"
+	"strings"
+	"testing"
+
+	. "go/types"
+)
+
+func testEval(t *testing.T, fset *token.FileSet, pkg *Package, pos token.Pos, expr string, typ Type, typStr, valStr string) {
+	gotTv, err := Eval(fset, pkg, pos, expr)
+	if err != nil {
+		t.Errorf("Eval(%q) failed: %s", expr, err)
+		return
+	}
+	if gotTv.Type == nil {
+		t.Errorf("Eval(%q) got nil type but no error", expr)
+		return
+	}
+
+	// compare types
+	if typ != nil {
+		// we have a type, check identity
+		if !Identical(gotTv.Type, typ) {
+			t.Errorf("Eval(%q) got type %s, want %s", expr, gotTv.Type, typ)
+			return
+		}
+	} else {
+		// we have a string, compare type string
+		gotStr := gotTv.Type.String()
+		if gotStr != typStr {
+			t.Errorf("Eval(%q) got type %s, want %s", expr, gotStr, typStr)
+			return
+		}
+	}
+
+	// compare values
+	gotStr := ""
+	if gotTv.Value != nil {
+		gotStr = gotTv.Value.String()
+	}
+	if gotStr != valStr {
+		t.Errorf("Eval(%q) got value %s, want %s", expr, gotStr, valStr)
+	}
+}
+
+func TestEvalBasic(t *testing.T) {
+	fset := token.NewFileSet()
+	for _, typ := range Typ[Bool : String+1] {
+		testEval(t, fset, nil, token.NoPos, typ.Name(), typ, "", "")
+	}
+}
+
+func TestEvalComposite(t *testing.T) {
+	fset := token.NewFileSet()
+	for _, test := range independentTestTypes {
+		testEval(t, fset, nil, token.NoPos, test.src, nil, test.str, "")
+	}
+}
+
+func TestEvalArith(t *testing.T) {
+	var tests = []string{
+		`true`,
+		`false == false`,
+		`12345678 + 87654321 == 99999999`,
+		`10 * 20 == 200`,
+		`(1<<1000)*2 >> 100 == 2<<900`,
+		`"foo" + "bar" == "foobar"`,
+		`"abc" <= "bcd"`,
+		`len([10]struct{}{}) == 2*5`,
+	}
+	fset := token.NewFileSet()
+	for _, test := range tests {
+		testEval(t, fset, nil, token.NoPos, test, Typ[UntypedBool], "", "true")
+	}
+}
+
+func TestEvalPos(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	// The contents of /*-style comments are of the form
+	//	expr => value, type
+	// where value may be the empty string.
+	// Each expr is evaluated at the position of the comment
+	// and the result is compared with the expected value
+	// and type.
+	var sources = []string{
+		`
+		package p
+		import "fmt"
+		import m "math"
+		const c = 3.0
+		type T []int
+		func f(a int, s string) float64 {
+			fmt.Println("calling f")
+			_ = m.Pi // use package math
+			const d int = c + 1
+			var x int
+			x = a + len(s)
+			return float64(x)
+			/* true => true, untyped bool */
+			/* fmt.Println => , func(a ...interface{}) (n int, err error) */
+			/* c => 3, untyped float */
+			/* T => , p.T */
+			/* a => , int */
+			/* s => , string */
+			/* d => 4, int */
+			/* x => , int */
+			/* d/c => 1, int */
+			/* c/2 => 3/2, untyped float */
+			/* m.Pi < m.E => false, untyped bool */
+		}
+		`,
+		`
+		package p
+		/* c => 3, untyped float */
+		type T1 /* T1 => , p.T1 */ struct {}
+		var v1 /* v1 => , int */ = 42
+		func /* f1 => , func(v1 float64) */ f1(v1 float64) {
+			/* f1 => , func(v1 float64) */
+			/* v1 => , float64 */
+			var c /* c => 3, untyped float */ = "foo" /* c => , string */
+			{
+				var c struct {
+					c /* c => , string */ int
+				}
+				/* c => , struct{c int} */
+				_ = c
+			}
+			_ = func(a, b, c int) /* c => , string */ {
+				/* c => , int */
+			}
+			_ = c
+			type FT /* FT => , p.FT */ interface{}
+		}
+		`,
+		`
+		package p
+		/* T => , p.T */
+		`,
+	}
+
+	fset := token.NewFileSet()
+	var files []*ast.File
+	for i, src := range sources {
+		file, err := parser.ParseFile(fset, "p", src, parser.ParseComments)
+		if err != nil {
+			t.Fatalf("could not parse file %d: %s", i, err)
+		}
+		files = append(files, file)
+	}
+
+	conf := Config{Importer: importer.Default()}
+	pkg, err := conf.Check("p", fset, files, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, file := range files {
+		for _, group := range file.Comments {
+			for _, comment := range group.List {
+				s := comment.Text
+				if len(s) >= 4 && s[:2] == "/*" && s[len(s)-2:] == "*/" {
+					str, typ := split(s[2:len(s)-2], ", ")
+					str, val := split(str, "=>")
+					testEval(t, fset, pkg, comment.Pos(), str, nil, typ, val)
+				}
+			}
+		}
+	}
+}
+
+// split splits string s at the first occurrence of s.
+func split(s, sep string) (string, string) {
+	i := strings.Index(s, sep)
+	return strings.TrimSpace(s[:i]), strings.TrimSpace(s[i+len(sep):])
+}
diff --git a/libgo/go/go/types/example_test.go b/libgo/go/go/types/example_test.go
new file mode 100644
index 00000000000..9daad8765a8
--- /dev/null
+++ b/libgo/go/go/types/example_test.go
@@ -0,0 +1,312 @@
+// Copyright 2015 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.
+
+// Only run where builders (build.golang.org) have
+// access to compiled packages for import.
+//
+// +build ignore,!arm,!arm64,!nacl
+
+package types_test
+
+// This file shows examples of basic usage of the go/types API.
+//
+// To locate a Go package, use (*go/build.Context).Import.
+// To load, parse, and type-check a complete Go program
+// from source, use golang.org/x/tools/go/loader.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"log"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+// ExampleScope prints the tree of Scopes of a package created from a
+// set of parsed files.
+func ExampleScope() {
+	// Parse the source files for a package.
+	fset := token.NewFileSet()
+	var files []*ast.File
+	for _, file := range []struct{ name, input string }{
+		{"main.go", `
+package main
+import "fmt"
+func main() {
+	freezing := FToC(-18)
+	fmt.Println(freezing, Boiling) }
+`},
+		{"celsius.go", `
+package main
+import "fmt"
+type Celsius float64
+func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
+func FToC(f float64) Celsius { return Celsius(f - 32 / 9 * 5) }
+const Boiling Celsius = 100
+`},
+	} {
+		f, err := parser.ParseFile(fset, file.name, file.input, 0)
+		if err != nil {
+			log.Fatal(err)
+		}
+		files = append(files, f)
+	}
+
+	// Type-check a package consisting of these files.
+	// Type information for the imported "fmt" package
+	// comes from $GOROOT/pkg/$GOOS_$GOOARCH/fmt.a.
+	conf := types.Config{Importer: importer.Default()}
+	pkg, err := conf.Check("temperature", fset, files, nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Print the tree of scopes.
+	// For determinism, we redact addresses.
+	var buf bytes.Buffer
+	pkg.Scope().WriteTo(&buf, 0, true)
+	rx := regexp.MustCompile(` 0x[a-fA-F0-9]*`)
+	fmt.Println(rx.ReplaceAllString(buf.String(), ""))
+
+	// Output:
+	// package "temperature" scope {
+	// .  const temperature.Boiling temperature.Celsius
+	// .  type temperature.Celsius float64
+	// .  func temperature.FToC(f float64) temperature.Celsius
+	// .  func temperature.main()
+	//
+	// .  main.go scope {
+	// .  .  package fmt
+	//
+	// .  .  function scope {
+	// .  .  .  var freezing temperature.Celsius
+	// .  .  }.  }
+	// .  celsius.go scope {
+	// .  .  package fmt
+	//
+	// .  .  function scope {
+	// .  .  .  var c temperature.Celsius
+	// .  .  }
+	// .  .  function scope {
+	// .  .  .  var f float64
+	// .  .  }.  }}
+}
+
+// ExampleMethodSet prints the method sets of various types.
+func ExampleMethodSet() {
+	// Parse a single source file.
+	const input = `
+package temperature
+import "fmt"
+type Celsius float64
+func (c Celsius) String() string  { return fmt.Sprintf("%g°C", c) }
+func (c *Celsius) SetF(f float64) { *c = Celsius(f - 32 / 9 * 5) }
+`
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "celsius.go", input, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Type-check a package consisting of this file.
+	// Type information for the imported packages
+	// comes from $GOROOT/pkg/$GOOS_$GOOARCH/fmt.a.
+	conf := types.Config{Importer: importer.Default()}
+	pkg, err := conf.Check("temperature", fset, []*ast.File{f}, nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Print the method sets of Celsius and *Celsius.
+	celsius := pkg.Scope().Lookup("Celsius").Type()
+	for _, t := range []types.Type{celsius, types.NewPointer(celsius)} {
+		fmt.Printf("Method set of %s:\n", t)
+		mset := types.NewMethodSet(t)
+		for i := 0; i < mset.Len(); i++ {
+			fmt.Println(mset.At(i))
+		}
+		fmt.Println()
+	}
+
+	// Output:
+	// Method set of temperature.Celsius:
+	// method (temperature.Celsius) String() string
+	//
+	// Method set of *temperature.Celsius:
+	// method (*temperature.Celsius) SetF(f float64)
+	// method (*temperature.Celsius) String() string
+}
+
+// ExampleInfo prints various facts recorded by the type checker in a
+// types.Info struct: definitions of and references to each named object,
+// and the type, value, and mode of every expression in the package.
+func ExampleInfo() {
+	// Parse a single source file.
+	const input = `
+package fib
+
+type S string
+
+var a, b, c = len(b), S(c), "hello"
+
+func fib(x int) int {
+	if x < 2 {
+		return x
+	}
+	return fib(x-1) - fib(x-2)
+}`
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "fib.go", input, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Type-check the package.
+	// We create an empty map for each kind of input
+	// we're interested in, and Check populates them.
+	info := types.Info{
+		Types: make(map[ast.Expr]types.TypeAndValue),
+		Defs:  make(map[*ast.Ident]types.Object),
+		Uses:  make(map[*ast.Ident]types.Object),
+	}
+	var conf types.Config
+	pkg, err := conf.Check("fib", fset, []*ast.File{f}, &info)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Print package-level variables in initialization order.
+	fmt.Printf("InitOrder: %v\n\n", info.InitOrder)
+
+	// For each named object, print the line and
+	// column of its definition and each of its uses.
+	fmt.Println("Defs and Uses of each named object:")
+	usesByObj := make(map[types.Object][]string)
+	for id, obj := range info.Uses {
+		posn := fset.Position(id.Pos())
+		lineCol := fmt.Sprintf("%d:%d", posn.Line, posn.Column)
+		usesByObj[obj] = append(usesByObj[obj], lineCol)
+	}
+	var items []string
+	for obj, uses := range usesByObj {
+		sort.Strings(uses)
+		item := fmt.Sprintf("%s:\n  defined at %s\n  used at %s",
+			types.ObjectString(obj, types.RelativeTo(pkg)),
+			fset.Position(obj.Pos()),
+			strings.Join(uses, ", "))
+		items = append(items, item)
+	}
+	sort.Strings(items) // sort by line:col, in effect
+	fmt.Println(strings.Join(items, "\n"))
+	fmt.Println()
+
+	fmt.Println("Types and Values of each expression:")
+	items = nil
+	for expr, tv := range info.Types {
+		var buf bytes.Buffer
+		posn := fset.Position(expr.Pos())
+		tvstr := tv.Type.String()
+		if tv.Value != nil {
+			tvstr += " = " + tv.Value.String()
+		}
+		// line:col | expr | mode : type = value
+		fmt.Fprintf(&buf, "%2d:%2d | %-19s | %-7s : %s",
+			posn.Line, posn.Column, exprString(fset, expr),
+			mode(tv), tvstr)
+		items = append(items, buf.String())
+	}
+	sort.Strings(items)
+	fmt.Println(strings.Join(items, "\n"))
+
+	// Output:
+	// InitOrder: [c = "hello" b = S(c) a = len(b)]
+	//
+	// Defs and Uses of each named object:
+	// builtin len:
+	//   defined at -
+	//   used at 6:15
+	// func fib(x int) int:
+	//   defined at fib.go:8:6
+	//   used at 12:20, 12:9
+	// type S string:
+	//   defined at fib.go:4:6
+	//   used at 6:23
+	// type int int:
+	//   defined at -
+	//   used at 8:12, 8:17
+	// type string string:
+	//   defined at -
+	//   used at 4:8
+	// var b S:
+	//   defined at fib.go:6:8
+	//   used at 6:19
+	// var c string:
+	//   defined at fib.go:6:11
+	//   used at 6:25
+	// var x int:
+	//   defined at fib.go:8:10
+	//   used at 10:10, 12:13, 12:24, 9:5
+	//
+	// Types and Values of each expression:
+	//  4: 8 | string              | type    : string
+	//  6:15 | len                 | builtin : func(string) int
+	//  6:15 | len(b)              | value   : int
+	//  6:19 | b                   | var     : fib.S
+	//  6:23 | S                   | type    : fib.S
+	//  6:23 | S(c)                | value   : fib.S
+	//  6:25 | c                   | var     : string
+	//  6:29 | "hello"             | value   : string = "hello"
+	//  8:12 | int                 | type    : int
+	//  8:17 | int                 | type    : int
+	//  9: 5 | x                   | var     : int
+	//  9: 5 | x < 2               | value   : untyped bool
+	//  9: 9 | 2                   | value   : int = 2
+	// 10:10 | x                   | var     : int
+	// 12: 9 | fib                 | value   : func(x int) int
+	// 12: 9 | fib(x - 1)          | value   : int
+	// 12: 9 | fib(x-1) - fib(x-2) | value   : int
+	// 12:13 | x                   | var     : int
+	// 12:13 | x - 1               | value   : int
+	// 12:15 | 1                   | value   : int = 1
+	// 12:20 | fib                 | value   : func(x int) int
+	// 12:20 | fib(x - 2)          | value   : int
+	// 12:24 | x                   | var     : int
+	// 12:24 | x - 2               | value   : int
+	// 12:26 | 2                   | value   : int = 2
+}
+
+func mode(tv types.TypeAndValue) string {
+	switch {
+	case tv.IsVoid():
+		return "void"
+	case tv.IsType():
+		return "type"
+	case tv.IsBuiltin():
+		return "builtin"
+	case tv.IsNil():
+		return "nil"
+	case tv.Assignable():
+		if tv.Addressable() {
+			return "var"
+		}
+		return "mapindex"
+	case tv.IsValue():
+		return "value"
+	default:
+		return "unknown"
+	}
+}
+
+func exprString(fset *token.FileSet, expr ast.Expr) string {
+	var buf bytes.Buffer
+	format.Node(&buf, fset, expr)
+	return buf.String()
+}
diff --git a/libgo/go/go/types/expr.go b/libgo/go/go/types/expr.go
new file mode 100644
index 00000000000..7d00dd5fa5d
--- /dev/null
+++ b/libgo/go/go/types/expr.go
@@ -0,0 +1,1496 @@
+// 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.
+
+// This file implements typechecking of expressions.
+
+package types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"math"
+)
+
+/*
+Basic algorithm:
+
+Expressions are checked recursively, top down. Expression checker functions
+are generally of the form:
+
+  func f(x *operand, e *ast.Expr, ...)
+
+where e is the expression to be checked, and x is the result of the check.
+The check performed by f may fail in which case x.mode == invalid, and
+related error messages will have been issued by f.
+
+If a hint argument is present, it is the composite literal element type
+of an outer composite literal; it is used to type-check composite literal
+elements that have no explicit type specification in the source
+(e.g.: []T{{...}, {...}}, the hint is the type T in this case).
+
+All expressions are checked via rawExpr, which dispatches according
+to expression kind. Upon returning, rawExpr is recording the types and
+constant values for all expressions that have an untyped type (those types
+may change on the way up in the expression tree). Usually these are constants,
+but the results of comparisons or non-constant shifts of untyped constants
+may also be untyped, but not constant.
+
+Untyped expressions may eventually become fully typed (i.e., not untyped),
+typically when the value is assigned to a variable, or is used otherwise.
+The updateExprType method is used to record this final type and update
+the recorded types: the type-checked expression tree is again traversed down,
+and the new type is propagated as needed. Untyped constant expression values
+that become fully typed must now be representable by the full type (constant
+sub-expression trees are left alone except for their roots). This mechanism
+ensures that a client sees the actual (run-time) type an untyped value would
+have. It also permits type-checking of lhs shift operands "as if the shift
+were not present": when updateExprType visits an untyped lhs shift operand
+and assigns it it's final type, that type must be an integer type, and a
+constant lhs must be representable as an integer.
+
+When an expression gets its final type, either on the way out from rawExpr,
+on the way down in updateExprType, or at the end of the type checker run,
+the type (and constant value, if any) is recorded via Info.Types, if present.
+*/
+
+type opPredicates map[token.Token]func(Type) bool
+
+var unaryOpPredicates = opPredicates{
+	token.ADD: isNumeric,
+	token.SUB: isNumeric,
+	token.XOR: isInteger,
+	token.NOT: isBoolean,
+}
+
+func (check *Checker) op(m opPredicates, x *operand, op token.Token) bool {
+	if pred := m[op]; pred != nil {
+		if !pred(x.typ) {
+			check.invalidOp(x.pos(), "operator %s not defined for %s", op, x)
+			return false
+		}
+	} else {
+		check.invalidAST(x.pos(), "unknown operator %s", op)
+		return false
+	}
+	return true
+}
+
+// The unary expression e may be nil. It's passed in for better error messages only.
+func (check *Checker) unary(x *operand, e *ast.UnaryExpr, op token.Token) {
+	switch op {
+	case token.AND:
+		// spec: "As an exception to the addressability
+		// requirement x may also be a composite literal."
+		if _, ok := unparen(x.expr).(*ast.CompositeLit); !ok && x.mode != variable {
+			check.invalidOp(x.pos(), "cannot take address of %s", x)
+			x.mode = invalid
+			return
+		}
+		x.mode = value
+		x.typ = &Pointer{base: x.typ}
+		return
+
+	case token.ARROW:
+		typ, ok := x.typ.Underlying().(*Chan)
+		if !ok {
+			check.invalidOp(x.pos(), "cannot receive from non-channel %s", x)
+			x.mode = invalid
+			return
+		}
+		if typ.dir == SendOnly {
+			check.invalidOp(x.pos(), "cannot receive from send-only channel %s", x)
+			x.mode = invalid
+			return
+		}
+		x.mode = commaok
+		x.typ = typ.elem
+		check.hasCallOrRecv = true
+		return
+	}
+
+	if !check.op(unaryOpPredicates, x, op) {
+		x.mode = invalid
+		return
+	}
+
+	if x.mode == constant_ {
+		typ := x.typ.Underlying().(*Basic)
+		var prec uint
+		if isUnsigned(typ) {
+			prec = uint(check.conf.sizeof(typ) * 8)
+		}
+		x.val = constant.UnaryOp(op, x.val, prec)
+		// Typed constants must be representable in
+		// their type after each constant operation.
+		if isTyped(typ) {
+			if e != nil {
+				x.expr = e // for better error message
+			}
+			check.representable(x, typ)
+		}
+		return
+	}
+
+	x.mode = value
+	// x.typ remains unchanged
+}
+
+func isShift(op token.Token) bool {
+	return op == token.SHL || op == token.SHR
+}
+
+func isComparison(op token.Token) bool {
+	// Note: tokens are not ordered well to make this much easier
+	switch op {
+	case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
+		return true
+	}
+	return false
+}
+
+func fitsFloat32(x constant.Value) bool {
+	f32, _ := constant.Float32Val(x)
+	f := float64(f32)
+	return !math.IsInf(f, 0)
+}
+
+func roundFloat32(x constant.Value) constant.Value {
+	f32, _ := constant.Float32Val(x)
+	f := float64(f32)
+	if !math.IsInf(f, 0) {
+		return constant.MakeFloat64(f)
+	}
+	return nil
+}
+
+func fitsFloat64(x constant.Value) bool {
+	f, _ := constant.Float64Val(x)
+	return !math.IsInf(f, 0)
+}
+
+func roundFloat64(x constant.Value) constant.Value {
+	f, _ := constant.Float64Val(x)
+	if !math.IsInf(f, 0) {
+		return constant.MakeFloat64(f)
+	}
+	return nil
+}
+
+// representableConst reports whether x can be represented as
+// value of the given basic type kind and for the configuration
+// provided (only needed for int/uint sizes).
+//
+// If rounded != nil, *rounded is set to the rounded value of x for
+// representable floating-point values; it is left alone otherwise.
+// It is ok to provide the addressof the first argument for rounded.
+func representableConst(x constant.Value, conf *Config, as BasicKind, rounded *constant.Value) bool {
+	switch x.Kind() {
+	case constant.Unknown:
+		return true
+
+	case constant.Bool:
+		return as == Bool || as == UntypedBool
+
+	case constant.Int:
+		if x, ok := constant.Int64Val(x); ok {
+			switch as {
+			case Int:
+				var s = uint(conf.sizeof(Typ[as])) * 8
+				return int64(-1)<<(s-1) <= x && x <= int64(1)<<(s-1)-1
+			case Int8:
+				const s = 8
+				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+			case Int16:
+				const s = 16
+				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+			case Int32:
+				const s = 32
+				return -1<<(s-1) <= x && x <= 1<<(s-1)-1
+			case Int64:
+				return true
+			case Uint, Uintptr:
+				if s := uint(conf.sizeof(Typ[as])) * 8; s < 64 {
+					return 0 <= x && x <= int64(1)<<s-1
+				}
+				return 0 <= x
+			case Uint8:
+				const s = 8
+				return 0 <= x && x <= 1<<s-1
+			case Uint16:
+				const s = 16
+				return 0 <= x && x <= 1<<s-1
+			case Uint32:
+				const s = 32
+				return 0 <= x && x <= 1<<s-1
+			case Uint64:
+				return 0 <= x
+			case Float32, Float64, Complex64, Complex128,
+				UntypedInt, UntypedFloat, UntypedComplex:
+				return true
+			}
+		}
+
+		n := constant.BitLen(x)
+		switch as {
+		case Uint, Uintptr:
+			var s = uint(conf.sizeof(Typ[as])) * 8
+			return constant.Sign(x) >= 0 && n <= int(s)
+		case Uint64:
+			return constant.Sign(x) >= 0 && n <= 64
+		case Float32, Complex64:
+			if rounded == nil {
+				return fitsFloat32(x)
+			}
+			r := roundFloat32(x)
+			if r != nil {
+				*rounded = r
+				return true
+			}
+		case Float64, Complex128:
+			if rounded == nil {
+				return fitsFloat64(x)
+			}
+			r := roundFloat64(x)
+			if r != nil {
+				*rounded = r
+				return true
+			}
+		case UntypedInt, UntypedFloat, UntypedComplex:
+			return true
+		}
+
+	case constant.Float:
+		switch as {
+		case Float32, Complex64:
+			if rounded == nil {
+				return fitsFloat32(x)
+			}
+			r := roundFloat32(x)
+			if r != nil {
+				*rounded = r
+				return true
+			}
+		case Float64, Complex128:
+			if rounded == nil {
+				return fitsFloat64(x)
+			}
+			r := roundFloat64(x)
+			if r != nil {
+				*rounded = r
+				return true
+			}
+		case UntypedFloat, UntypedComplex:
+			return true
+		}
+
+	case constant.Complex:
+		switch as {
+		case Complex64:
+			if rounded == nil {
+				return fitsFloat32(constant.Real(x)) && fitsFloat32(constant.Imag(x))
+			}
+			re := roundFloat32(constant.Real(x))
+			im := roundFloat32(constant.Imag(x))
+			if re != nil && im != nil {
+				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
+				return true
+			}
+		case Complex128:
+			if rounded == nil {
+				return fitsFloat64(constant.Real(x)) && fitsFloat64(constant.Imag(x))
+			}
+			re := roundFloat64(constant.Real(x))
+			im := roundFloat64(constant.Imag(x))
+			if re != nil && im != nil {
+				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
+				return true
+			}
+		case UntypedComplex:
+			return true
+		}
+
+	case constant.String:
+		return as == String || as == UntypedString
+
+	default:
+		unreachable()
+	}
+
+	return false
+}
+
+// representable checks that a constant operand is representable in the given basic type.
+func (check *Checker) representable(x *operand, typ *Basic) {
+	assert(x.mode == constant_)
+	if !representableConst(x.val, check.conf, typ.kind, &x.val) {
+		var msg string
+		if isNumeric(x.typ) && isNumeric(typ) {
+			// numeric conversion : error msg
+			//
+			// integer -> integer : overflows
+			// integer -> float   : overflows (actually not possible)
+			// float   -> integer : truncated
+			// float   -> float   : overflows
+			//
+			if !isInteger(x.typ) && isInteger(typ) {
+				msg = "%s truncated to %s"
+			} else {
+				msg = "%s overflows %s"
+			}
+		} else {
+			msg = "cannot convert %s to %s"
+		}
+		check.errorf(x.pos(), msg, x, typ)
+		x.mode = invalid
+	}
+}
+
+// updateExprType updates the type of x to typ and invokes itself
+// recursively for the operands of x, depending on expression kind.
+// If typ is still an untyped and not the final type, updateExprType
+// only updates the recorded untyped type for x and possibly its
+// operands. Otherwise (i.e., typ is not an untyped type anymore,
+// or it is the final type for x), the type and value are recorded.
+// Also, if x is a constant, it must be representable as a value of typ,
+// and if x is the (formerly untyped) lhs operand of a non-constant
+// shift, it must be an integer value.
+//
+func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
+	old, found := check.untyped[x]
+	if !found {
+		return // nothing to do
+	}
+
+	// update operands of x if necessary
+	switch x := x.(type) {
+	case *ast.BadExpr,
+		*ast.FuncLit,
+		*ast.CompositeLit,
+		*ast.IndexExpr,
+		*ast.SliceExpr,
+		*ast.TypeAssertExpr,
+		*ast.StarExpr,
+		*ast.KeyValueExpr,
+		*ast.ArrayType,
+		*ast.StructType,
+		*ast.FuncType,
+		*ast.InterfaceType,
+		*ast.MapType,
+		*ast.ChanType:
+		// These expression are never untyped - nothing to do.
+		// The respective sub-expressions got their final types
+		// upon assignment or use.
+		if debug {
+			check.dump("%s: found old type(%s): %s (new: %s)", x.Pos(), x, old.typ, typ)
+			unreachable()
+		}
+		return
+
+	case *ast.CallExpr:
+		// Resulting in an untyped constant (e.g., built-in complex).
+		// The respective calls take care of calling updateExprType
+		// for the arguments if necessary.
+
+	case *ast.Ident, *ast.BasicLit, *ast.SelectorExpr:
+		// An identifier denoting a constant, a constant literal,
+		// or a qualified identifier (imported untyped constant).
+		// No operands to take care of.
+
+	case *ast.ParenExpr:
+		check.updateExprType(x.X, typ, final)
+
+	case *ast.UnaryExpr:
+		// If x is a constant, the operands were constants.
+		// They don't need to be updated since they never
+		// get "materialized" into a typed value; and they
+		// will be processed at the end of the type check.
+		if old.val != nil {
+			break
+		}
+		check.updateExprType(x.X, typ, final)
+
+	case *ast.BinaryExpr:
+		if old.val != nil {
+			break // see comment for unary expressions
+		}
+		if isComparison(x.Op) {
+			// The result type is independent of operand types
+			// and the operand types must have final types.
+		} else if isShift(x.Op) {
+			// The result type depends only on lhs operand.
+			// The rhs type was updated when checking the shift.
+			check.updateExprType(x.X, typ, final)
+		} else {
+			// The operand types match the result type.
+			check.updateExprType(x.X, typ, final)
+			check.updateExprType(x.Y, typ, final)
+		}
+
+	default:
+		unreachable()
+	}
+
+	// If the new type is not final and still untyped, just
+	// update the recorded type.
+	if !final && isUntyped(typ) {
+		old.typ = typ.Underlying().(*Basic)
+		check.untyped[x] = old
+		return
+	}
+
+	// Otherwise we have the final (typed or untyped type).
+	// Remove it from the map of yet untyped expressions.
+	delete(check.untyped, x)
+
+	// If x is the lhs of a shift, its final type must be integer.
+	// We already know from the shift check that it is representable
+	// as an integer if it is a constant.
+	if old.isLhs && !isInteger(typ) {
+		check.invalidOp(x.Pos(), "shifted operand %s (type %s) must be integer", x, typ)
+		return
+	}
+
+	// Everything's fine, record final type and value for x.
+	check.recordTypeAndValue(x, old.mode, typ, old.val)
+}
+
+// updateExprVal updates the value of x to val.
+func (check *Checker) updateExprVal(x ast.Expr, val constant.Value) {
+	if info, ok := check.untyped[x]; ok {
+		info.val = val
+		check.untyped[x] = info
+	}
+}
+
+// convertUntyped attempts to set the type of an untyped value to the target type.
+func (check *Checker) convertUntyped(x *operand, target Type) {
+	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
+		return
+	}
+
+	// TODO(gri) Sloppy code - clean up. This function is central
+	//           to assignment and expression checking.
+
+	if isUntyped(target) {
+		// both x and target are untyped
+		xkind := x.typ.(*Basic).kind
+		tkind := target.(*Basic).kind
+		if isNumeric(x.typ) && isNumeric(target) {
+			if xkind < tkind {
+				x.typ = target
+				check.updateExprType(x.expr, target, false)
+			}
+		} else if xkind != tkind {
+			goto Error
+		}
+		return
+	}
+
+	// typed target
+	switch t := target.Underlying().(type) {
+	case *Basic:
+		if x.mode == constant_ {
+			check.representable(x, t)
+			if x.mode == invalid {
+				return
+			}
+			// expression value may have been rounded - update if needed
+			// TODO(gri) A floating-point value may silently underflow to
+			// zero. If it was negative, the sign is lost. See issue 6898.
+			check.updateExprVal(x.expr, x.val)
+		} else {
+			// Non-constant untyped values may appear as the
+			// result of comparisons (untyped bool), intermediate
+			// (delayed-checked) rhs operands of shifts, and as
+			// the value nil.
+			switch x.typ.(*Basic).kind {
+			case UntypedBool:
+				if !isBoolean(target) {
+					goto Error
+				}
+			case UntypedInt, UntypedRune, UntypedFloat, UntypedComplex:
+				if !isNumeric(target) {
+					goto Error
+				}
+			case UntypedString:
+				// Non-constant untyped string values are not
+				// permitted by the spec and should not occur.
+				unreachable()
+			case UntypedNil:
+				// Unsafe.Pointer is a basic type that includes nil.
+				if !hasNil(target) {
+					goto Error
+				}
+			default:
+				goto Error
+			}
+		}
+	case *Interface:
+		if !x.isNil() && !t.Empty() /* empty interfaces are ok */ {
+			goto Error
+		}
+		// Update operand types to the default type rather then
+		// the target (interface) type: values must have concrete
+		// dynamic types. If the value is nil, keep it untyped
+		// (this is important for tools such as go vet which need
+		// the dynamic type for argument checking of say, print
+		// functions)
+		if x.isNil() {
+			target = Typ[UntypedNil]
+		} else {
+			// cannot assign untyped values to non-empty interfaces
+			if !t.Empty() {
+				goto Error
+			}
+			target = defaultType(x.typ)
+		}
+	case *Pointer, *Signature, *Slice, *Map, *Chan:
+		if !x.isNil() {
+			goto Error
+		}
+		// keep nil untyped - see comment for interfaces, above
+		target = Typ[UntypedNil]
+	default:
+		goto Error
+	}
+
+	x.typ = target
+	check.updateExprType(x.expr, target, true) // UntypedNils are final
+	return
+
+Error:
+	check.errorf(x.pos(), "cannot convert %s to %s", x, target)
+	x.mode = invalid
+}
+
+func (check *Checker) comparison(x, y *operand, op token.Token) {
+	// spec: "In any comparison, the first operand must be assignable
+	// to the type of the second operand, or vice versa."
+	err := ""
+	if x.assignableTo(check.conf, y.typ) || y.assignableTo(check.conf, x.typ) {
+		defined := false
+		switch op {
+		case token.EQL, token.NEQ:
+			// spec: "The equality operators == and != apply to operands that are comparable."
+			defined = Comparable(x.typ) || x.isNil() && hasNil(y.typ) || y.isNil() && hasNil(x.typ)
+		case token.LSS, token.LEQ, token.GTR, token.GEQ:
+			// spec: The ordering operators <, <=, >, and >= apply to operands that are ordered."
+			defined = isOrdered(x.typ)
+		default:
+			unreachable()
+		}
+		if !defined {
+			typ := x.typ
+			if x.isNil() {
+				typ = y.typ
+			}
+			err = check.sprintf("operator %s not defined for %s", op, typ)
+		}
+	} else {
+		err = check.sprintf("mismatched types %s and %s", x.typ, y.typ)
+	}
+
+	if err != "" {
+		check.errorf(x.pos(), "cannot compare %s %s %s (%s)", x.expr, op, y.expr, err)
+		x.mode = invalid
+		return
+	}
+
+	if x.mode == constant_ && y.mode == constant_ {
+		x.val = constant.MakeBool(constant.Compare(x.val, op, y.val))
+		// The operands are never materialized; no need to update
+		// their types.
+	} else {
+		x.mode = value
+		// The operands have now their final types, which at run-
+		// time will be materialized. Update the expression trees.
+		// If the current types are untyped, the materialized type
+		// is the respective default type.
+		check.updateExprType(x.expr, defaultType(x.typ), true)
+		check.updateExprType(y.expr, defaultType(y.typ), true)
+	}
+
+	// spec: "Comparison operators compare two operands and yield
+	//        an untyped boolean value."
+	x.typ = Typ[UntypedBool]
+}
+
+func (check *Checker) shift(x, y *operand, op token.Token) {
+	untypedx := isUntyped(x.typ)
+
+	// The lhs must be of integer type or be representable
+	// as an integer; otherwise the shift has no chance.
+	if !x.isInteger() {
+		check.invalidOp(x.pos(), "shifted operand %s must be integer", x)
+		x.mode = invalid
+		return
+	}
+
+	// spec: "The right operand in a shift expression must have unsigned
+	// integer type or be an untyped constant that can be converted to
+	// unsigned integer type."
+	switch {
+	case isInteger(y.typ) && isUnsigned(y.typ):
+		// nothing to do
+	case isUntyped(y.typ):
+		check.convertUntyped(y, Typ[UntypedInt])
+		if y.mode == invalid {
+			x.mode = invalid
+			return
+		}
+	default:
+		check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
+		x.mode = invalid
+		return
+	}
+
+	if x.mode == constant_ {
+		if y.mode == constant_ {
+			// rhs must be an integer value
+			if !y.isInteger() {
+				check.invalidOp(y.pos(), "shift count %s must be unsigned integer", y)
+				x.mode = invalid
+				return
+			}
+			// rhs must be within reasonable bounds
+			const stupidShift = 1023 - 1 + 52 // so we can express smallestFloat64
+			s, ok := constant.Uint64Val(y.val)
+			if !ok || s > stupidShift {
+				check.invalidOp(y.pos(), "stupid shift count %s", y)
+				x.mode = invalid
+				return
+			}
+			// The lhs is representable as an integer but may not be an integer
+			// (e.g., 2.0, an untyped float) - this can only happen for untyped
+			// non-integer numeric constants. Correct the type so that the shift
+			// result is of integer type.
+			if !isInteger(x.typ) {
+				x.typ = Typ[UntypedInt]
+			}
+			x.val = constant.Shift(x.val, op, uint(s))
+			return
+		}
+
+		// non-constant shift with constant lhs
+		if untypedx {
+			// spec: "If the left operand of a non-constant shift
+			// expression is an untyped constant, the type of the
+			// constant is what it would be if the shift expression
+			// were replaced by its left operand alone.".
+			//
+			// Delay operand checking until we know the final type:
+			// The lhs expression must be in the untyped map, mark
+			// the entry as lhs shift operand.
+			info, found := check.untyped[x.expr]
+			assert(found)
+			info.isLhs = true
+			check.untyped[x.expr] = info
+			// keep x's type
+			x.mode = value
+			return
+		}
+	}
+
+	// constant rhs must be >= 0
+	if y.mode == constant_ && constant.Sign(y.val) < 0 {
+		check.invalidOp(y.pos(), "shift count %s must not be negative", y)
+	}
+
+	// non-constant shift - lhs must be an integer
+	if !isInteger(x.typ) {
+		check.invalidOp(x.pos(), "shifted operand %s must be integer", x)
+		x.mode = invalid
+		return
+	}
+
+	x.mode = value
+}
+
+var binaryOpPredicates = opPredicates{
+	token.ADD: func(typ Type) bool { return isNumeric(typ) || isString(typ) },
+	token.SUB: isNumeric,
+	token.MUL: isNumeric,
+	token.QUO: isNumeric,
+	token.REM: isInteger,
+
+	token.AND:     isInteger,
+	token.OR:      isInteger,
+	token.XOR:     isInteger,
+	token.AND_NOT: isInteger,
+
+	token.LAND: isBoolean,
+	token.LOR:  isBoolean,
+}
+
+// The binary expression e may be nil. It's passed in for better error messages only.
+func (check *Checker) binary(x *operand, e *ast.BinaryExpr, lhs, rhs ast.Expr, op token.Token) {
+	var y operand
+
+	check.expr(x, lhs)
+	check.expr(&y, rhs)
+
+	if x.mode == invalid {
+		return
+	}
+	if y.mode == invalid {
+		x.mode = invalid
+		x.expr = y.expr
+		return
+	}
+
+	if isShift(op) {
+		check.shift(x, &y, op)
+		return
+	}
+
+	check.convertUntyped(x, y.typ)
+	if x.mode == invalid {
+		return
+	}
+	check.convertUntyped(&y, x.typ)
+	if y.mode == invalid {
+		x.mode = invalid
+		return
+	}
+
+	if isComparison(op) {
+		check.comparison(x, &y, op)
+		return
+	}
+
+	if !Identical(x.typ, y.typ) {
+		// only report an error if we have valid types
+		// (otherwise we had an error reported elsewhere already)
+		if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
+			check.invalidOp(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
+		}
+		x.mode = invalid
+		return
+	}
+
+	if !check.op(binaryOpPredicates, x, op) {
+		x.mode = invalid
+		return
+	}
+
+	if (op == token.QUO || op == token.REM) && (x.mode == constant_ || isInteger(x.typ)) && y.mode == constant_ && constant.Sign(y.val) == 0 {
+		check.invalidOp(y.pos(), "division by zero")
+		x.mode = invalid
+		return
+	}
+
+	if x.mode == constant_ && y.mode == constant_ {
+		typ := x.typ.Underlying().(*Basic)
+		// force integer division of integer operands
+		if op == token.QUO && isInteger(typ) {
+			op = token.QUO_ASSIGN
+		}
+		x.val = constant.BinaryOp(x.val, op, y.val)
+		// Typed constants must be representable in
+		// their type after each constant operation.
+		if isTyped(typ) {
+			if e != nil {
+				x.expr = e // for better error message
+			}
+			check.representable(x, typ)
+		}
+		return
+	}
+
+	x.mode = value
+	// x.typ is unchanged
+}
+
+// index checks an index expression for validity.
+// If max >= 0, it is the upper bound for index.
+// If index is valid and the result i >= 0, then i is the constant value of index.
+func (check *Checker) index(index ast.Expr, max int64) (i int64, valid bool) {
+	var x operand
+	check.expr(&x, index)
+	if x.mode == invalid {
+		return
+	}
+
+	// an untyped constant must be representable as Int
+	check.convertUntyped(&x, Typ[Int])
+	if x.mode == invalid {
+		return
+	}
+
+	// the index must be of integer type
+	if !isInteger(x.typ) {
+		check.invalidArg(x.pos(), "index %s must be integer", &x)
+		return
+	}
+
+	// a constant index i must be in bounds
+	if x.mode == constant_ {
+		if constant.Sign(x.val) < 0 {
+			check.invalidArg(x.pos(), "index %s must not be negative", &x)
+			return
+		}
+		i, valid = constant.Int64Val(x.val)
+		if !valid || max >= 0 && i >= max {
+			check.errorf(x.pos(), "index %s is out of bounds", &x)
+			return i, false
+		}
+		// 0 <= i [ && i < max ]
+		return i, true
+	}
+
+	return -1, true
+}
+
+// indexElts checks the elements (elts) of an array or slice composite literal
+// against the literal's element type (typ), and the element indices against
+// the literal length if known (length >= 0). It returns the length of the
+// literal (maximum index value + 1).
+//
+func (check *Checker) indexedElts(elts []ast.Expr, typ Type, length int64) int64 {
+	visited := make(map[int64]bool, len(elts))
+	var index, max int64
+	for _, e := range elts {
+		// determine and check index
+		validIndex := false
+		eval := e
+		if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
+			if i, ok := check.index(kv.Key, length); ok {
+				if i >= 0 {
+					index = i
+					validIndex = true
+				} else {
+					check.errorf(e.Pos(), "index %s must be integer constant", kv.Key)
+				}
+			}
+			eval = kv.Value
+		} else if length >= 0 && index >= length {
+			check.errorf(e.Pos(), "index %d is out of bounds (>= %d)", index, length)
+		} else {
+			validIndex = true
+		}
+
+		// if we have a valid index, check for duplicate entries
+		if validIndex {
+			if visited[index] {
+				check.errorf(e.Pos(), "duplicate index %d in array or slice literal", index)
+			}
+			visited[index] = true
+		}
+		index++
+		if index > max {
+			max = index
+		}
+
+		// check element against composite literal element type
+		var x operand
+		check.exprWithHint(&x, eval, typ)
+		if !check.assignment(&x, typ) && x.mode != invalid {
+			check.errorf(x.pos(), "cannot use %s as %s value in array or slice literal", &x, typ)
+		}
+	}
+	return max
+}
+
+// exprKind describes the kind of an expression; the kind
+// determines if an expression is valid in 'statement context'.
+type exprKind int
+
+const (
+	conversion exprKind = iota
+	expression
+	statement
+)
+
+// rawExpr typechecks expression e and initializes x with the expression
+// value or type. If an error occurred, x.mode is set to invalid.
+// If hint != nil, it is the type of a composite literal element.
+//
+func (check *Checker) rawExpr(x *operand, e ast.Expr, hint Type) exprKind {
+	if trace {
+		check.trace(e.Pos(), "%s", e)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(e.Pos(), "=> %s", x)
+		}()
+	}
+
+	kind := check.exprInternal(x, e, hint)
+
+	// convert x into a user-friendly set of values
+	// TODO(gri) this code can be simplified
+	var typ Type
+	var val constant.Value
+	switch x.mode {
+	case invalid:
+		typ = Typ[Invalid]
+	case novalue:
+		typ = (*Tuple)(nil)
+	case constant_:
+		typ = x.typ
+		val = x.val
+	default:
+		typ = x.typ
+	}
+	assert(x.expr != nil && typ != nil)
+
+	if isUntyped(typ) {
+		// delay type and value recording until we know the type
+		// or until the end of type checking
+		check.rememberUntyped(x.expr, false, x.mode, typ.(*Basic), val)
+	} else {
+		check.recordTypeAndValue(e, x.mode, typ, val)
+	}
+
+	return kind
+}
+
+// exprInternal contains the core of type checking of expressions.
+// Must only be called by rawExpr.
+//
+func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
+	// make sure x has a valid state in case of bailout
+	// (was issue 5770)
+	x.mode = invalid
+	x.typ = Typ[Invalid]
+
+	switch e := e.(type) {
+	case *ast.BadExpr:
+		goto Error // error was reported before
+
+	case *ast.Ident:
+		check.ident(x, e, nil, nil)
+
+	case *ast.Ellipsis:
+		// ellipses are handled explicitly where they are legal
+		// (array composite literals and parameter lists)
+		check.error(e.Pos(), "invalid use of '...'")
+		goto Error
+
+	case *ast.BasicLit:
+		x.setConst(e.Kind, e.Value)
+		if x.mode == invalid {
+			check.invalidAST(e.Pos(), "invalid literal %v", e.Value)
+			goto Error
+		}
+
+	case *ast.FuncLit:
+		if sig, ok := check.typ(e.Type).(*Signature); ok {
+			// Anonymous functions are considered part of the
+			// init expression/func declaration which contains
+			// them: use existing package-level declaration info.
+			check.funcBody(check.decl, "", sig, e.Body)
+			x.mode = value
+			x.typ = sig
+		} else {
+			check.invalidAST(e.Pos(), "invalid function literal %s", e)
+			goto Error
+		}
+
+	case *ast.CompositeLit:
+		typ := hint
+		openArray := false
+		if e.Type != nil {
+			// [...]T array types may only appear with composite literals.
+			// Check for them here so we don't have to handle ... in general.
+			typ = nil
+			if atyp, _ := e.Type.(*ast.ArrayType); atyp != nil && atyp.Len != nil {
+				if ellip, _ := atyp.Len.(*ast.Ellipsis); ellip != nil && ellip.Elt == nil {
+					// We have an "open" [...]T array type.
+					// Create a new ArrayType with unknown length (-1)
+					// and finish setting it up after analyzing the literal.
+					typ = &Array{len: -1, elem: check.typ(atyp.Elt)}
+					openArray = true
+				}
+			}
+			if typ == nil {
+				typ = check.typ(e.Type)
+			}
+		}
+		if typ == nil {
+			// TODO(gri) provide better error messages depending on context
+			check.error(e.Pos(), "missing type in composite literal")
+			goto Error
+		}
+
+		switch typ, _ := deref(typ); utyp := typ.Underlying().(type) {
+		case *Struct:
+			if len(e.Elts) == 0 {
+				break
+			}
+			fields := utyp.fields
+			if _, ok := e.Elts[0].(*ast.KeyValueExpr); ok {
+				// all elements must have keys
+				visited := make([]bool, len(fields))
+				for _, e := range e.Elts {
+					kv, _ := e.(*ast.KeyValueExpr)
+					if kv == nil {
+						check.error(e.Pos(), "mixture of field:value and value elements in struct literal")
+						continue
+					}
+					key, _ := kv.Key.(*ast.Ident)
+					if key == nil {
+						check.errorf(kv.Pos(), "invalid field name %s in struct literal", kv.Key)
+						continue
+					}
+					i := fieldIndex(utyp.fields, check.pkg, key.Name)
+					if i < 0 {
+						check.errorf(kv.Pos(), "unknown field %s in struct literal", key.Name)
+						continue
+					}
+					fld := fields[i]
+					check.recordUse(key, fld)
+					// 0 <= i < len(fields)
+					if visited[i] {
+						check.errorf(kv.Pos(), "duplicate field name %s in struct literal", key.Name)
+						continue
+					}
+					visited[i] = true
+					check.expr(x, kv.Value)
+					etyp := fld.typ
+					if !check.assignment(x, etyp) {
+						if x.mode != invalid {
+							check.errorf(x.pos(), "cannot use %s as %s value in struct literal", x, etyp)
+						}
+						continue
+					}
+				}
+			} else {
+				// no element must have a key
+				for i, e := range e.Elts {
+					if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
+						check.error(kv.Pos(), "mixture of field:value and value elements in struct literal")
+						continue
+					}
+					check.expr(x, e)
+					if i >= len(fields) {
+						check.error(x.pos(), "too many values in struct literal")
+						break // cannot continue
+					}
+					// i < len(fields)
+					fld := fields[i]
+					if !fld.Exported() && fld.pkg != check.pkg {
+						check.errorf(x.pos(), "implicit assignment to unexported field %s in %s literal", fld.name, typ)
+						continue
+					}
+					etyp := fld.typ
+					if !check.assignment(x, etyp) {
+						if x.mode != invalid {
+							check.errorf(x.pos(), "cannot use %s as %s value in struct literal", x, etyp)
+						}
+						continue
+					}
+				}
+				if len(e.Elts) < len(fields) {
+					check.error(e.Rbrace, "too few values in struct literal")
+					// ok to continue
+				}
+			}
+
+		case *Array:
+			n := check.indexedElts(e.Elts, utyp.elem, utyp.len)
+			// if we have an "open" [...]T array, set the length now that we know it
+			if openArray {
+				utyp.len = n
+			}
+
+		case *Slice:
+			check.indexedElts(e.Elts, utyp.elem, -1)
+
+		case *Map:
+			visited := make(map[interface{}][]Type, len(e.Elts))
+			for _, e := range e.Elts {
+				kv, _ := e.(*ast.KeyValueExpr)
+				if kv == nil {
+					check.error(e.Pos(), "missing key in map literal")
+					continue
+				}
+				check.exprWithHint(x, kv.Key, utyp.key)
+				if !check.assignment(x, utyp.key) {
+					if x.mode != invalid {
+						check.errorf(x.pos(), "cannot use %s as %s key in map literal", x, utyp.key)
+					}
+					continue
+				}
+				if x.mode == constant_ {
+					duplicate := false
+					// if the key is of interface type, the type is also significant when checking for duplicates
+					if _, ok := utyp.key.Underlying().(*Interface); ok {
+						for _, vtyp := range visited[x.val] {
+							if Identical(vtyp, x.typ) {
+								duplicate = true
+								break
+							}
+						}
+						visited[x.val] = append(visited[x.val], x.typ)
+					} else {
+						_, duplicate = visited[x.val]
+						visited[x.val] = nil
+					}
+					if duplicate {
+						check.errorf(x.pos(), "duplicate key %s in map literal", x.val)
+						continue
+					}
+				}
+				check.exprWithHint(x, kv.Value, utyp.elem)
+				if !check.assignment(x, utyp.elem) {
+					if x.mode != invalid {
+						check.errorf(x.pos(), "cannot use %s as %s value in map literal", x, utyp.elem)
+					}
+					continue
+				}
+			}
+
+		default:
+			// if utyp is invalid, an error was reported before
+			if utyp != Typ[Invalid] {
+				check.errorf(e.Pos(), "invalid composite literal type %s", typ)
+				goto Error
+			}
+		}
+
+		x.mode = value
+		x.typ = typ
+
+	case *ast.ParenExpr:
+		kind := check.rawExpr(x, e.X, nil)
+		x.expr = e
+		return kind
+
+	case *ast.SelectorExpr:
+		check.selector(x, e)
+
+	case *ast.IndexExpr:
+		check.expr(x, e.X)
+		if x.mode == invalid {
+			goto Error
+		}
+
+		valid := false
+		length := int64(-1) // valid if >= 0
+		switch typ := x.typ.Underlying().(type) {
+		case *Basic:
+			if isString(typ) {
+				valid = true
+				if x.mode == constant_ {
+					length = int64(len(constant.StringVal(x.val)))
+				}
+				// an indexed string always yields a byte value
+				// (not a constant) even if the string and the
+				// index are constant
+				x.mode = value
+				x.typ = universeByte // use 'byte' name
+			}
+
+		case *Array:
+			valid = true
+			length = typ.len
+			if x.mode != variable {
+				x.mode = value
+			}
+			x.typ = typ.elem
+
+		case *Pointer:
+			if typ, _ := typ.base.Underlying().(*Array); typ != nil {
+				valid = true
+				length = typ.len
+				x.mode = variable
+				x.typ = typ.elem
+			}
+
+		case *Slice:
+			valid = true
+			x.mode = variable
+			x.typ = typ.elem
+
+		case *Map:
+			var key operand
+			check.expr(&key, e.Index)
+			if !check.assignment(&key, typ.key) {
+				if key.mode != invalid {
+					check.invalidOp(key.pos(), "cannot use %s as map index of type %s", &key, typ.key)
+				}
+				goto Error
+			}
+			x.mode = mapindex
+			x.typ = typ.elem
+			x.expr = e
+			return expression
+		}
+
+		if !valid {
+			check.invalidOp(x.pos(), "cannot index %s", x)
+			goto Error
+		}
+
+		if e.Index == nil {
+			check.invalidAST(e.Pos(), "missing index for %s", x)
+			goto Error
+		}
+
+		check.index(e.Index, length)
+		// ok to continue
+
+	case *ast.SliceExpr:
+		check.expr(x, e.X)
+		if x.mode == invalid {
+			goto Error
+		}
+
+		valid := false
+		length := int64(-1) // valid if >= 0
+		switch typ := x.typ.Underlying().(type) {
+		case *Basic:
+			if isString(typ) {
+				if slice3(e) {
+					check.invalidOp(x.pos(), "3-index slice of string")
+					goto Error
+				}
+				valid = true
+				if x.mode == constant_ {
+					length = int64(len(constant.StringVal(x.val)))
+				}
+				// spec: "For untyped string operands the result
+				// is a non-constant value of type string."
+				if typ.kind == UntypedString {
+					x.typ = Typ[String]
+				}
+			}
+
+		case *Array:
+			valid = true
+			length = typ.len
+			if x.mode != variable {
+				check.invalidOp(x.pos(), "cannot slice %s (value not addressable)", x)
+				goto Error
+			}
+			x.typ = &Slice{elem: typ.elem}
+
+		case *Pointer:
+			if typ, _ := typ.base.Underlying().(*Array); typ != nil {
+				valid = true
+				length = typ.len
+				x.typ = &Slice{elem: typ.elem}
+			}
+
+		case *Slice:
+			valid = true
+			// x.typ doesn't change
+		}
+
+		if !valid {
+			check.invalidOp(x.pos(), "cannot slice %s", x)
+			goto Error
+		}
+
+		x.mode = value
+
+		// spec: "Only the first index may be omitted; it defaults to 0."
+		if slice3(e) && (e.High == nil || sliceMax(e) == nil) {
+			check.error(e.Rbrack, "2nd and 3rd index required in 3-index slice")
+			goto Error
+		}
+
+		// check indices
+		var ind [3]int64
+		for i, expr := range []ast.Expr{e.Low, e.High, sliceMax(e)} {
+			x := int64(-1)
+			switch {
+			case expr != nil:
+				// The "capacity" is only known statically for strings, arrays,
+				// and pointers to arrays, and it is the same as the length for
+				// those types.
+				max := int64(-1)
+				if length >= 0 {
+					max = length + 1
+				}
+				if t, ok := check.index(expr, max); ok && t >= 0 {
+					x = t
+				}
+			case i == 0:
+				// default is 0 for the first index
+				x = 0
+			case length >= 0:
+				// default is length (== capacity) otherwise
+				x = length
+			}
+			ind[i] = x
+		}
+
+		// constant indices must be in range
+		// (check.index already checks that existing indices >= 0)
+	L:
+		for i, x := range ind[:len(ind)-1] {
+			if x > 0 {
+				for _, y := range ind[i+1:] {
+					if y >= 0 && x > y {
+						check.errorf(e.Rbrack, "invalid slice indices: %d > %d", x, y)
+						break L // only report one error, ok to continue
+					}
+				}
+			}
+		}
+
+	case *ast.TypeAssertExpr:
+		check.expr(x, e.X)
+		if x.mode == invalid {
+			goto Error
+		}
+		xtyp, _ := x.typ.Underlying().(*Interface)
+		if xtyp == nil {
+			check.invalidOp(x.pos(), "%s is not an interface", x)
+			goto Error
+		}
+		// x.(type) expressions are handled explicitly in type switches
+		if e.Type == nil {
+			check.invalidAST(e.Pos(), "use of .(type) outside type switch")
+			goto Error
+		}
+		T := check.typ(e.Type)
+		if T == Typ[Invalid] {
+			goto Error
+		}
+		check.typeAssertion(x.pos(), x, xtyp, T)
+		x.mode = commaok
+		x.typ = T
+
+	case *ast.CallExpr:
+		return check.call(x, e)
+
+	case *ast.StarExpr:
+		check.exprOrType(x, e.X)
+		switch x.mode {
+		case invalid:
+			goto Error
+		case typexpr:
+			x.typ = &Pointer{base: x.typ}
+		default:
+			if typ, ok := x.typ.Underlying().(*Pointer); ok {
+				x.mode = variable
+				x.typ = typ.base
+			} else {
+				check.invalidOp(x.pos(), "cannot indirect %s", x)
+				goto Error
+			}
+		}
+
+	case *ast.UnaryExpr:
+		check.expr(x, e.X)
+		if x.mode == invalid {
+			goto Error
+		}
+		check.unary(x, e, e.Op)
+		if x.mode == invalid {
+			goto Error
+		}
+		if e.Op == token.ARROW {
+			x.expr = e
+			return statement // receive operations may appear in statement context
+		}
+
+	case *ast.BinaryExpr:
+		check.binary(x, e, e.X, e.Y, e.Op)
+		if x.mode == invalid {
+			goto Error
+		}
+
+	case *ast.KeyValueExpr:
+		// key:value expressions are handled in composite literals
+		check.invalidAST(e.Pos(), "no key:value expected")
+		goto Error
+
+	case *ast.ArrayType, *ast.StructType, *ast.FuncType,
+		*ast.InterfaceType, *ast.MapType, *ast.ChanType:
+		x.mode = typexpr
+		x.typ = check.typ(e)
+		// Note: rawExpr (caller of exprInternal) will call check.recordTypeAndValue
+		// even though check.typ has already called it. This is fine as both
+		// times the same expression and type are recorded. It is also not a
+		// performance issue because we only reach here for composite literal
+		// types, which are comparatively rare.
+
+	default:
+		panic(fmt.Sprintf("%s: unknown expression type %T", check.fset.Position(e.Pos()), e))
+	}
+
+	// everything went well
+	x.expr = e
+	return expression
+
+Error:
+	x.mode = invalid
+	x.expr = e
+	return statement // avoid follow-up errors
+}
+
+// typeAssertion checks that x.(T) is legal; xtyp must be the type of x.
+func (check *Checker) typeAssertion(pos token.Pos, x *operand, xtyp *Interface, T Type) {
+	method, wrongType := assertableTo(xtyp, T)
+	if method == nil {
+		return
+	}
+
+	var msg string
+	if wrongType {
+		msg = "wrong type for method"
+	} else {
+		msg = "missing method"
+	}
+	check.errorf(pos, "%s cannot have dynamic type %s (%s %s)", x, T, msg, method.name)
+}
+
+// expr typechecks expression e and initializes x with the expression value.
+// If an error occurred, x.mode is set to invalid.
+//
+func (check *Checker) expr(x *operand, e ast.Expr) {
+	check.rawExpr(x, e, nil)
+	var msg string
+	switch x.mode {
+	default:
+		return
+	case novalue:
+		msg = "used as value"
+	case builtin:
+		msg = "must be called"
+	case typexpr:
+		msg = "is not an expression"
+	}
+	check.errorf(x.pos(), "%s %s", x, msg)
+	x.mode = invalid
+}
+
+// exprWithHint typechecks expression e and initializes x with the expression value.
+// If an error occurred, x.mode is set to invalid.
+// If hint != nil, it is the type of a composite literal element.
+//
+func (check *Checker) exprWithHint(x *operand, e ast.Expr, hint Type) {
+	assert(hint != nil)
+	check.rawExpr(x, e, hint)
+	var msg string
+	switch x.mode {
+	default:
+		return
+	case novalue:
+		msg = "used as value"
+	case builtin:
+		msg = "must be called"
+	case typexpr:
+		msg = "is not an expression"
+	}
+	check.errorf(x.pos(), "%s %s", x, msg)
+	x.mode = invalid
+}
+
+// exprOrType typechecks expression or type e and initializes x with the expression value or type.
+// If an error occurred, x.mode is set to invalid.
+//
+func (check *Checker) exprOrType(x *operand, e ast.Expr) {
+	check.rawExpr(x, e, nil)
+	if x.mode == novalue {
+		check.errorf(x.pos(), "%s used as value or type", x)
+		x.mode = invalid
+	}
+}
diff --git a/libgo/go/go/types/exprstring.go b/libgo/go/go/types/exprstring.go
new file mode 100644
index 00000000000..370bdf35324
--- /dev/null
+++ b/libgo/go/go/types/exprstring.go
@@ -0,0 +1,220 @@
+// Copyright 2013 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.
+
+// This file implements printing of expressions.
+
+package types
+
+import (
+	"bytes"
+	"go/ast"
+)
+
+// ExprString returns the (possibly simplified) string representation for x.
+func ExprString(x ast.Expr) string {
+	var buf bytes.Buffer
+	WriteExpr(&buf, x)
+	return buf.String()
+}
+
+// WriteExpr writes the (possibly simplified) string representation for x to buf.
+func WriteExpr(buf *bytes.Buffer, x ast.Expr) {
+	// The AST preserves source-level parentheses so there is
+	// no need to introduce them here to correct for different
+	// operator precedences. (This assumes that the AST was
+	// generated by a Go parser.)
+
+	switch x := x.(type) {
+	default:
+		buf.WriteString("(bad expr)") // nil, ast.BadExpr, ast.KeyValueExpr
+
+	case *ast.Ident:
+		buf.WriteString(x.Name)
+
+	case *ast.Ellipsis:
+		buf.WriteString("...")
+		if x.Elt != nil {
+			WriteExpr(buf, x.Elt)
+		}
+
+	case *ast.BasicLit:
+		buf.WriteString(x.Value)
+
+	case *ast.FuncLit:
+		buf.WriteByte('(')
+		WriteExpr(buf, x.Type)
+		buf.WriteString(" literal)") // simplified
+
+	case *ast.CompositeLit:
+		buf.WriteByte('(')
+		WriteExpr(buf, x.Type)
+		buf.WriteString(" literal)") // simplified
+
+	case *ast.ParenExpr:
+		buf.WriteByte('(')
+		WriteExpr(buf, x.X)
+		buf.WriteByte(')')
+
+	case *ast.SelectorExpr:
+		WriteExpr(buf, x.X)
+		buf.WriteByte('.')
+		buf.WriteString(x.Sel.Name)
+
+	case *ast.IndexExpr:
+		WriteExpr(buf, x.X)
+		buf.WriteByte('[')
+		WriteExpr(buf, x.Index)
+		buf.WriteByte(']')
+
+	case *ast.SliceExpr:
+		WriteExpr(buf, x.X)
+		buf.WriteByte('[')
+		if x.Low != nil {
+			WriteExpr(buf, x.Low)
+		}
+		buf.WriteByte(':')
+		if x.High != nil {
+			WriteExpr(buf, x.High)
+		}
+		if x.Slice3 {
+			buf.WriteByte(':')
+			if x.Max != nil {
+				WriteExpr(buf, x.Max)
+			}
+		}
+		buf.WriteByte(']')
+
+	case *ast.TypeAssertExpr:
+		WriteExpr(buf, x.X)
+		buf.WriteString(".(")
+		WriteExpr(buf, x.Type)
+		buf.WriteByte(')')
+
+	case *ast.CallExpr:
+		WriteExpr(buf, x.Fun)
+		buf.WriteByte('(')
+		for i, arg := range x.Args {
+			if i > 0 {
+				buf.WriteString(", ")
+			}
+			WriteExpr(buf, arg)
+		}
+		if x.Ellipsis.IsValid() {
+			buf.WriteString("...")
+		}
+		buf.WriteByte(')')
+
+	case *ast.StarExpr:
+		buf.WriteByte('*')
+		WriteExpr(buf, x.X)
+
+	case *ast.UnaryExpr:
+		buf.WriteString(x.Op.String())
+		WriteExpr(buf, x.X)
+
+	case *ast.BinaryExpr:
+		WriteExpr(buf, x.X)
+		buf.WriteByte(' ')
+		buf.WriteString(x.Op.String())
+		buf.WriteByte(' ')
+		WriteExpr(buf, x.Y)
+
+	case *ast.ArrayType:
+		buf.WriteByte('[')
+		if x.Len != nil {
+			WriteExpr(buf, x.Len)
+		}
+		buf.WriteByte(']')
+		WriteExpr(buf, x.Elt)
+
+	case *ast.StructType:
+		buf.WriteString("struct{")
+		writeFieldList(buf, x.Fields, "; ", false)
+		buf.WriteByte('}')
+
+	case *ast.FuncType:
+		buf.WriteString("func")
+		writeSigExpr(buf, x)
+
+	case *ast.InterfaceType:
+		buf.WriteString("interface{")
+		writeFieldList(buf, x.Methods, "; ", true)
+		buf.WriteByte('}')
+
+	case *ast.MapType:
+		buf.WriteString("map[")
+		WriteExpr(buf, x.Key)
+		buf.WriteByte(']')
+		WriteExpr(buf, x.Value)
+
+	case *ast.ChanType:
+		var s string
+		switch x.Dir {
+		case ast.SEND:
+			s = "chan<- "
+		case ast.RECV:
+			s = "<-chan "
+		default:
+			s = "chan "
+		}
+		buf.WriteString(s)
+		WriteExpr(buf, x.Value)
+	}
+}
+
+func writeSigExpr(buf *bytes.Buffer, sig *ast.FuncType) {
+	buf.WriteByte('(')
+	writeFieldList(buf, sig.Params, ", ", false)
+	buf.WriteByte(')')
+
+	res := sig.Results
+	n := res.NumFields()
+	if n == 0 {
+		// no result
+		return
+	}
+
+	buf.WriteByte(' ')
+	if n == 1 && len(res.List[0].Names) == 0 {
+		// single unnamed result
+		WriteExpr(buf, res.List[0].Type)
+		return
+	}
+
+	// multiple or named result(s)
+	buf.WriteByte('(')
+	writeFieldList(buf, res, ", ", false)
+	buf.WriteByte(')')
+}
+
+func writeFieldList(buf *bytes.Buffer, fields *ast.FieldList, sep string, iface bool) {
+	for i, f := range fields.List {
+		if i > 0 {
+			buf.WriteString(sep)
+		}
+
+		// field list names
+		for i, name := range f.Names {
+			if i > 0 {
+				buf.WriteString(", ")
+			}
+			buf.WriteString(name.Name)
+		}
+
+		// types of interface methods consist of signatures only
+		if sig, _ := f.Type.(*ast.FuncType); sig != nil && iface {
+			writeSigExpr(buf, sig)
+			continue
+		}
+
+		// named fields are separated with a blank from the field type
+		if len(f.Names) > 0 {
+			buf.WriteByte(' ')
+		}
+
+		WriteExpr(buf, f.Type)
+
+		// ignore tag
+	}
+}
diff --git a/libgo/go/go/types/exprstring_test.go b/libgo/go/go/types/exprstring_test.go
new file mode 100644
index 00000000000..51102881c9f
--- /dev/null
+++ b/libgo/go/go/types/exprstring_test.go
@@ -0,0 +1,94 @@
+// Copyright 2013 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 types_test
+
+import (
+	"go/parser"
+	"testing"
+
+	. "go/types"
+)
+
+var testExprs = []testEntry{
+	// basic type literals
+	dup("x"),
+	dup("true"),
+	dup("42"),
+	dup("3.1415"),
+	dup("2.71828i"),
+	dup(`'a'`),
+	dup(`"foo"`),
+	dup("`bar`"),
+
+	// func and composite literals
+	{"func(){}", "(func() literal)"},
+	{"func(x int) complex128 {}", "(func(x int) complex128 literal)"},
+	{"[]int{1, 2, 3}", "([]int literal)"},
+
+	// non-type expressions
+	dup("(x)"),
+	dup("x.f"),
+	dup("a[i]"),
+
+	dup("s[:]"),
+	dup("s[i:]"),
+	dup("s[:j]"),
+	dup("s[i:j]"),
+	dup("s[:j:k]"),
+	dup("s[i:j:k]"),
+
+	dup("x.(T)"),
+
+	dup("x.([10]int)"),
+	dup("x.([...]int)"),
+
+	dup("x.(struct{})"),
+	dup("x.(struct{x int; y, z float32; E})"),
+
+	dup("x.(func())"),
+	dup("x.(func(x int))"),
+	dup("x.(func() int)"),
+	dup("x.(func(x, y int, z float32) (r int))"),
+	dup("x.(func(a, b, c int))"),
+	dup("x.(func(x ...T))"),
+
+	dup("x.(interface{})"),
+	dup("x.(interface{m(); n(x int); E})"),
+	dup("x.(interface{m(); n(x int) T; E; F})"),
+
+	dup("x.(map[K]V)"),
+
+	dup("x.(chan E)"),
+	dup("x.(<-chan E)"),
+	dup("x.(chan<- chan int)"),
+	dup("x.(chan<- <-chan int)"),
+	dup("x.(<-chan chan int)"),
+	dup("x.(chan (<-chan int))"),
+
+	dup("f()"),
+	dup("f(x)"),
+	dup("int(x)"),
+	dup("f(x, x + y)"),
+	dup("f(s...)"),
+	dup("f(a, s...)"),
+
+	dup("*x"),
+	dup("&x"),
+	dup("x + y"),
+	dup("x + y << (2 * s)"),
+}
+
+func TestExprString(t *testing.T) {
+	for _, test := range testExprs {
+		x, err := parser.ParseExpr(test.src)
+		if err != nil {
+			t.Errorf("%s: %s", test.src, err)
+			continue
+		}
+		if got := ExprString(x); got != test.str {
+			t.Errorf("%s: got %s, want %s", test.src, got, test.str)
+		}
+	}
+}
diff --git a/libgo/go/go/types/go11.go b/libgo/go/go/types/go11.go
new file mode 100644
index 00000000000..cf41cabeeac
--- /dev/null
+++ b/libgo/go/go/types/go11.go
@@ -0,0 +1,17 @@
+// Copyright 2013 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.
+
+// +build !go1.2
+
+package types
+
+import "go/ast"
+
+func slice3(x *ast.SliceExpr) bool {
+	return false
+}
+
+func sliceMax(x *ast.SliceExpr) ast.Expr {
+	return nil
+}
diff --git a/libgo/go/go/types/go12.go b/libgo/go/go/types/go12.go
new file mode 100644
index 00000000000..20174421540
--- /dev/null
+++ b/libgo/go/go/types/go12.go
@@ -0,0 +1,17 @@
+// Copyright 2013 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.
+
+// +build go1.2
+
+package types
+
+import "go/ast"
+
+func slice3(x *ast.SliceExpr) bool {
+	return x.Slice3
+}
+
+func sliceMax(x *ast.SliceExpr) ast.Expr {
+	return x.Max
+}
diff --git a/libgo/go/go/types/hilbert_test.go b/libgo/go/go/types/hilbert_test.go
new file mode 100644
index 00000000000..cfd51b1d649
--- /dev/null
+++ b/libgo/go/go/types/hilbert_test.go
@@ -0,0 +1,234 @@
+// Copyright 2013 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 types_test
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"testing"
+
+	. "go/types"
+)
+
+var (
+	H   = flag.Int("H", 5, "Hilbert matrix size")
+	out = flag.String("out", "", "write generated program to out")
+)
+
+func TestHilbert(t *testing.T) {
+	// generate source
+	src := program(*H, *out)
+	if *out != "" {
+		ioutil.WriteFile(*out, src, 0666)
+		return
+	}
+
+	// parse source
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "hilbert.go", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// type-check file
+	DefPredeclaredTestFuncs() // define assert built-in
+	conf := Config{Importer: importer.Default()}
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func program(n int, out string) []byte {
+	var g gen
+
+	g.p(`// WARNING: GENERATED FILE - DO NOT MODIFY MANUALLY!
+// (To generate, in go/types directory: go test -run=Hilbert -H=%d -out=%q)
+
+// This program tests arbitrary precision constant arithmetic
+// by generating the constant elements of a Hilbert matrix H,
+// its inverse I, and the product P = H*I. The product should
+// be the identity matrix.
+package main
+
+func main() {
+	if !ok {
+		printProduct()
+		return
+	}
+	println("PASS")
+}
+
+`, n, out)
+	g.hilbert(n)
+	g.inverse(n)
+	g.product(n)
+	g.verify(n)
+	g.printProduct(n)
+	g.binomials(2*n - 1)
+	g.factorials(2*n - 1)
+
+	return g.Bytes()
+}
+
+type gen struct {
+	bytes.Buffer
+}
+
+func (g *gen) p(format string, args ...interface{}) {
+	fmt.Fprintf(&g.Buffer, format, args...)
+}
+
+func (g *gen) hilbert(n int) {
+	g.p(`// Hilbert matrix, n = %d
+const (
+`, n)
+	for i := 0; i < n; i++ {
+		g.p("\t")
+		for j := 0; j < n; j++ {
+			if j > 0 {
+				g.p(", ")
+			}
+			g.p("h%d_%d", i, j)
+		}
+		if i == 0 {
+			g.p(" = ")
+			for j := 0; j < n; j++ {
+				if j > 0 {
+					g.p(", ")
+				}
+				g.p("1.0/(iota + %d)", j+1)
+			}
+		}
+		g.p("\n")
+	}
+	g.p(")\n\n")
+}
+
+func (g *gen) inverse(n int) {
+	g.p(`// Inverse Hilbert matrix
+const (
+`)
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			s := "+"
+			if (i+j)&1 != 0 {
+				s = "-"
+			}
+			g.p("\ti%d_%d = %s%d * b%d_%d * b%d_%d * b%d_%d * b%d_%d\n",
+				i, j, s, i+j+1, n+i, n-j-1, n+j, n-i-1, i+j, i, i+j, i)
+		}
+		g.p("\n")
+	}
+	g.p(")\n\n")
+}
+
+func (g *gen) product(n int) {
+	g.p(`// Product matrix
+const (
+`)
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			g.p("\tp%d_%d = ", i, j)
+			for k := 0; k < n; k++ {
+				if k > 0 {
+					g.p(" + ")
+				}
+				g.p("h%d_%d*i%d_%d", i, k, k, j)
+			}
+			g.p("\n")
+		}
+		g.p("\n")
+	}
+	g.p(")\n\n")
+}
+
+func (g *gen) verify(n int) {
+	g.p(`// Verify that product is the identity matrix
+const ok =
+`)
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			if j == 0 {
+				g.p("\t")
+			} else {
+				g.p(" && ")
+			}
+			v := 0
+			if i == j {
+				v = 1
+			}
+			g.p("p%d_%d == %d", i, j, v)
+		}
+		g.p(" &&\n")
+	}
+	g.p("\ttrue\n\n")
+
+	// verify ok at type-check time
+	if *out == "" {
+		g.p("const _ = assert(ok)\n\n")
+	}
+}
+
+func (g *gen) printProduct(n int) {
+	g.p("func printProduct() {\n")
+	for i := 0; i < n; i++ {
+		g.p("\tprintln(")
+		for j := 0; j < n; j++ {
+			if j > 0 {
+				g.p(", ")
+			}
+			g.p("p%d_%d", i, j)
+		}
+		g.p(")\n")
+	}
+	g.p("}\n\n")
+}
+
+func (g *gen) mulRange(a, b int) {
+	if a > b {
+		g.p("1")
+		return
+	}
+	for i := a; i <= b; i++ {
+		if i > a {
+			g.p("*")
+		}
+		g.p("%d", i)
+	}
+}
+
+func (g *gen) binomials(n int) {
+	g.p(`// Binomials
+const (
+`)
+	for j := 0; j <= n; j++ {
+		if j > 0 {
+			g.p("\n")
+		}
+		for k := 0; k <= j; k++ {
+			g.p("\tb%d_%d = f%d / (f%d*f%d)\n", j, k, j, k, j-k)
+		}
+	}
+	g.p(")\n\n")
+}
+
+func (g *gen) factorials(n int) {
+	g.p(`// Factorials
+const (
+	f0 = 1
+	f1 = 1
+`)
+	for i := 2; i <= n; i++ {
+		g.p("\tf%d = f%d * %d\n", i, i-1, i)
+	}
+	g.p(")\n\n")
+}
diff --git a/libgo/go/go/types/initorder.go b/libgo/go/go/types/initorder.go
new file mode 100644
index 00000000000..0fd567b2691
--- /dev/null
+++ b/libgo/go/go/types/initorder.go
@@ -0,0 +1,222 @@
+// Copyright 2014 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 types
+
+import (
+	"container/heap"
+	"fmt"
+)
+
+// initOrder computes the Info.InitOrder for package variables.
+func (check *Checker) initOrder() {
+	// An InitOrder may already have been computed if a package is
+	// built from several calls to (*Checker).Files.  Clear it.
+	check.Info.InitOrder = check.Info.InitOrder[:0]
+
+	// compute the object dependency graph and
+	// initialize a priority queue with the list
+	// of graph nodes
+	pq := nodeQueue(dependencyGraph(check.objMap))
+	heap.Init(&pq)
+
+	const debug = false
+	if debug {
+		fmt.Printf("package %s: object dependency graph\n", check.pkg.Name())
+		for _, n := range pq {
+			for _, o := range n.out {
+				fmt.Printf("\t%s -> %s\n", n.obj.Name(), o.obj.Name())
+			}
+		}
+		fmt.Println()
+		fmt.Printf("package %s: initialization order\n", check.pkg.Name())
+	}
+
+	// determine initialization order by removing the highest priority node
+	// (the one with the fewest dependencies) and its edges from the graph,
+	// repeatedly, until there are no nodes left.
+	// In a valid Go program, those nodes always have zero dependencies (after
+	// removing all incoming dependencies), otherwise there are initialization
+	// cycles.
+	mark := 0
+	emitted := make(map[*declInfo]bool)
+	for len(pq) > 0 {
+		// get the next node
+		n := heap.Pop(&pq).(*objNode)
+
+		// if n still depends on other nodes, we have a cycle
+		if n.in > 0 {
+			mark++ // mark nodes using a different value each time
+			cycle := findPath(n, n, mark)
+			if i := valIndex(cycle); i >= 0 {
+				check.reportCycle(cycle, i)
+			}
+			// ok to continue, but the variable initialization order
+			// will be incorrect at this point since it assumes no
+			// cycle errors
+		}
+
+		// reduce dependency count of all dependent nodes
+		// and update priority queue
+		for _, out := range n.out {
+			out.in--
+			heap.Fix(&pq, out.index)
+		}
+
+		// record the init order for variables with initializers only
+		v, _ := n.obj.(*Var)
+		info := check.objMap[v]
+		if v == nil || !info.hasInitializer() {
+			continue
+		}
+
+		// n:1 variable declarations such as: a, b = f()
+		// introduce a node for each lhs variable (here: a, b);
+		// but they all have the same initializer - emit only
+		// one, for the first variable seen
+		if emitted[info] {
+			continue // initializer already emitted, if any
+		}
+		emitted[info] = true
+
+		infoLhs := info.lhs // possibly nil (see declInfo.lhs field comment)
+		if infoLhs == nil {
+			infoLhs = []*Var{v}
+		}
+		init := &Initializer{infoLhs, info.init}
+		check.Info.InitOrder = append(check.Info.InitOrder, init)
+
+		if debug {
+			fmt.Printf("\t%s\n", init)
+		}
+	}
+
+	if debug {
+		fmt.Println()
+	}
+}
+
+// findPath returns the (reversed) list of nodes z, ... c, b, a,
+// such that there is a path (list of edges) from a to z.
+// If there is no such path, the result is nil.
+// Nodes marked with the value mark are considered "visited";
+// unvisited nodes are marked during the graph search.
+func findPath(a, z *objNode, mark int) []*objNode {
+	if a.mark == mark {
+		return nil // node already seen
+	}
+	a.mark = mark
+
+	for _, n := range a.out {
+		if n == z {
+			return []*objNode{z}
+		}
+		if P := findPath(n, z, mark); P != nil {
+			return append(P, n)
+		}
+	}
+
+	return nil
+}
+
+// valIndex returns the index of the first constant or variable in a,
+// if any; or a value < 0.
+func valIndex(a []*objNode) int {
+	for i, n := range a {
+		switch n.obj.(type) {
+		case *Const, *Var:
+			return i
+		}
+	}
+	return -1
+}
+
+// reportCycle reports an error for the cycle starting at i.
+func (check *Checker) reportCycle(cycle []*objNode, i int) {
+	obj := cycle[i].obj
+	check.errorf(obj.Pos(), "initialization cycle for %s", obj.Name())
+	// print cycle
+	for _ = range cycle {
+		check.errorf(obj.Pos(), "\t%s refers to", obj.Name()) // secondary error, \t indented
+		i++
+		if i >= len(cycle) {
+			i = 0
+		}
+		obj = cycle[i].obj
+	}
+	check.errorf(obj.Pos(), "\t%s", obj.Name())
+}
+
+// An objNode represents a node in the object dependency graph.
+// Each node b in a.out represents an edge a->b indicating that
+// b depends on a.
+// Nodes may be marked for cycle detection. A node n is marked
+// if n.mark corresponds to the current mark value.
+type objNode struct {
+	obj   Object     // object represented by this node
+	in    int        // number of nodes this node depends on
+	out   []*objNode // list of nodes that depend on this node
+	index int        // node index in list of nodes
+	mark  int        // for cycle detection
+}
+
+// dependencyGraph computes the transposed object dependency graph
+// from the given objMap. The transposed graph is returned as a list
+// of nodes; an edge d->n indicates that node n depends on node d.
+func dependencyGraph(objMap map[Object]*declInfo) []*objNode {
+	// M maps each object to its corresponding node
+	M := make(map[Object]*objNode, len(objMap))
+	for obj := range objMap {
+		M[obj] = &objNode{obj: obj}
+	}
+
+	// G is the graph of nodes n
+	G := make([]*objNode, len(M))
+	i := 0
+	for obj, n := range M {
+		deps := objMap[obj].deps
+		n.in = len(deps)
+		for d := range deps {
+			d := M[d]                // node n depends on node d
+			d.out = append(d.out, n) // add edge d->n
+		}
+
+		G[i] = n
+		n.index = i
+		i++
+	}
+
+	return G
+}
+
+// nodeQueue implements the container/heap interface;
+// a nodeQueue may be used as a priority queue.
+type nodeQueue []*objNode
+
+func (a nodeQueue) Len() int { return len(a) }
+
+func (a nodeQueue) Swap(i, j int) {
+	x, y := a[i], a[j]
+	a[i], a[j] = y, x
+	x.index, y.index = j, i
+}
+
+func (a nodeQueue) Less(i, j int) bool {
+	x, y := a[i], a[j]
+	// nodes are prioritized by number of incoming dependencies (1st key)
+	// and source order (2nd key)
+	return x.in < y.in || x.in == y.in && x.obj.order() < y.obj.order()
+}
+
+func (a *nodeQueue) Push(x interface{}) {
+	panic("unreachable")
+}
+
+func (a *nodeQueue) Pop() interface{} {
+	n := len(*a)
+	x := (*a)[n-1]
+	x.index = -1 // for safety
+	*a = (*a)[:n-1]
+	return x
+}
diff --git a/libgo/go/go/types/issues_test.go b/libgo/go/go/types/issues_test.go
new file mode 100644
index 00000000000..672c78dfc20
--- /dev/null
+++ b/libgo/go/go/types/issues_test.go
@@ -0,0 +1,206 @@
+// Copyright 2013 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.
+
+// This file implements tests for various issues.
+
+package types_test
+
+import (
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"sort"
+	"strings"
+	"testing"
+
+	. "go/types"
+)
+
+func TestIssue5770(t *testing.T) {
+	src := `package p; type S struct{T}`
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	conf := Config{Importer: importer.Default()}
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, nil) // do not crash
+	want := "undeclared name: T"
+	if err == nil || !strings.Contains(err.Error(), want) {
+		t.Errorf("got: %v; want: %s", err, want)
+	}
+}
+
+func TestIssue5849(t *testing.T) {
+	src := `
+package p
+var (
+	s uint
+	_ = uint8(8)
+	_ = uint16(16) << s
+	_ = uint32(32 << s)
+	_ = uint64(64 << s + s)
+	_ = (interface{})("foo")
+	_ = (interface{})(nil)
+)`
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var conf Config
+	types := make(map[ast.Expr]TypeAndValue)
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Types: types})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for x, tv := range types {
+		var want Type
+		switch x := x.(type) {
+		case *ast.BasicLit:
+			switch x.Value {
+			case `8`:
+				want = Typ[Uint8]
+			case `16`:
+				want = Typ[Uint16]
+			case `32`:
+				want = Typ[Uint32]
+			case `64`:
+				want = Typ[Uint] // because of "+ s", s is of type uint
+			case `"foo"`:
+				want = Typ[String]
+			}
+		case *ast.Ident:
+			if x.Name == "nil" {
+				want = Typ[UntypedNil]
+			}
+		}
+		if want != nil && !Identical(tv.Type, want) {
+			t.Errorf("got %s; want %s", tv.Type, want)
+		}
+	}
+}
+
+func TestIssue6413(t *testing.T) {
+	src := `
+package p
+func f() int {
+	defer f()
+	go f()
+	return 0
+}
+`
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var conf Config
+	types := make(map[ast.Expr]TypeAndValue)
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Types: types})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := Typ[Int]
+	n := 0
+	for x, tv := range types {
+		if _, ok := x.(*ast.CallExpr); ok {
+			if tv.Type != want {
+				t.Errorf("%s: got %s; want %s", fset.Position(x.Pos()), tv.Type, want)
+			}
+			n++
+		}
+	}
+
+	if n != 2 {
+		t.Errorf("got %d CallExprs; want 2", n)
+	}
+}
+
+func TestIssue7245(t *testing.T) {
+	src := `
+package p
+func (T) m() (res bool) { return }
+type T struct{} // receiver type after method declaration
+`
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var conf Config
+	defs := make(map[*ast.Ident]Object)
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Defs: defs})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	m := f.Decls[0].(*ast.FuncDecl)
+	res1 := defs[m.Name].(*Func).Type().(*Signature).Results().At(0)
+	res2 := defs[m.Type.Results.List[0].Names[0]].(*Var)
+
+	if res1 != res2 {
+		t.Errorf("got %s (%p) != %s (%p)", res1, res2, res1, res2)
+	}
+}
+
+// This tests that uses of existing vars on the LHS of an assignment
+// are Uses, not Defs; and also that the (illegal) use of a non-var on
+// the LHS of an assignment is a Use nonetheless.
+func TestIssue7827(t *testing.T) {
+	const src = `
+package p
+func _() {
+	const w = 1        // defs w
+        x, y := 2, 3       // defs x, y
+        w, x, z := 4, 5, 6 // uses w, x, defs z; error: cannot assign to w
+        _, _, _ = x, y, z  // uses x, y, z
+}
+`
+	const want = `L3 defs func p._()
+L4 defs const w untyped int
+L5 defs var x int
+L5 defs var y int
+L6 defs var z int
+L6 uses const w untyped int
+L6 uses var x int
+L7 uses var x int
+L7 uses var y int
+L7 uses var z int`
+
+	f, err := parser.ParseFile(fset, "", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// don't abort at the first error
+	conf := Config{Error: func(err error) { t.Log(err) }}
+	defs := make(map[*ast.Ident]Object)
+	uses := make(map[*ast.Ident]Object)
+	_, err = conf.Check(f.Name.Name, fset, []*ast.File{f}, &Info{Defs: defs, Uses: uses})
+	if s := fmt.Sprint(err); !strings.HasSuffix(s, "cannot assign to w") {
+		t.Errorf("Check: unexpected error: %s", s)
+	}
+
+	var facts []string
+	for id, obj := range defs {
+		if obj != nil {
+			fact := fmt.Sprintf("L%d defs %s", fset.Position(id.Pos()).Line, obj)
+			facts = append(facts, fact)
+		}
+	}
+	for id, obj := range uses {
+		fact := fmt.Sprintf("L%d uses %s", fset.Position(id.Pos()).Line, obj)
+		facts = append(facts, fact)
+	}
+	sort.Strings(facts)
+
+	got := strings.Join(facts, "\n")
+	if got != want {
+		t.Errorf("Unexpected defs/uses\ngot:\n%s\nwant:\n%s", got, want)
+	}
+}
diff --git a/libgo/go/go/types/labels.go b/libgo/go/go/types/labels.go
new file mode 100644
index 00000000000..7364d4dbe68
--- /dev/null
+++ b/libgo/go/go/types/labels.go
@@ -0,0 +1,268 @@
+// Copyright 2013 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 types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// labels checks correct label use in body.
+func (check *Checker) labels(body *ast.BlockStmt) {
+	// set of all labels in this body
+	all := NewScope(nil, body.Pos(), body.End(), "label")
+
+	fwdJumps := check.blockBranches(all, nil, nil, body.List)
+
+	// If there are any forward jumps left, no label was found for
+	// the corresponding goto statements. Either those labels were
+	// never defined, or they are inside blocks and not reachable
+	// for the respective gotos.
+	for _, jmp := range fwdJumps {
+		var msg string
+		name := jmp.Label.Name
+		if alt := all.Lookup(name); alt != nil {
+			msg = "goto %s jumps into block"
+			alt.(*Label).used = true // avoid another error
+		} else {
+			msg = "label %s not declared"
+		}
+		check.errorf(jmp.Label.Pos(), msg, name)
+	}
+
+	// spec: "It is illegal to define a label that is never used."
+	for _, obj := range all.elems {
+		if lbl := obj.(*Label); !lbl.used {
+			check.softErrorf(lbl.pos, "label %s declared but not used", lbl.name)
+		}
+	}
+}
+
+// A block tracks label declarations in a block and its enclosing blocks.
+type block struct {
+	parent *block                      // enclosing block
+	lstmt  *ast.LabeledStmt            // labeled statement to which this block belongs, or nil
+	labels map[string]*ast.LabeledStmt // allocated lazily
+}
+
+// insert records a new label declaration for the current block.
+// The label must not have been declared before in any block.
+func (b *block) insert(s *ast.LabeledStmt) {
+	name := s.Label.Name
+	if debug {
+		assert(b.gotoTarget(name) == nil)
+	}
+	labels := b.labels
+	if labels == nil {
+		labels = make(map[string]*ast.LabeledStmt)
+		b.labels = labels
+	}
+	labels[name] = s
+}
+
+// gotoTarget returns the labeled statement in the current
+// or an enclosing block with the given label name, or nil.
+func (b *block) gotoTarget(name string) *ast.LabeledStmt {
+	for s := b; s != nil; s = s.parent {
+		if t := s.labels[name]; t != nil {
+			return t
+		}
+	}
+	return nil
+}
+
+// enclosingTarget returns the innermost enclosing labeled
+// statement with the given label name, or nil.
+func (b *block) enclosingTarget(name string) *ast.LabeledStmt {
+	for s := b; s != nil; s = s.parent {
+		if t := s.lstmt; t != nil && t.Label.Name == name {
+			return t
+		}
+	}
+	return nil
+}
+
+// blockBranches processes a block's statement list and returns the set of outgoing forward jumps.
+// all is the scope of all declared labels, parent the set of labels declared in the immediately
+// enclosing block, and lstmt is the labeled statement this block is associated with (or nil).
+func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *ast.LabeledStmt, list []ast.Stmt) []*ast.BranchStmt {
+	b := &block{parent: parent, lstmt: lstmt}
+
+	var (
+		varDeclPos         token.Pos
+		fwdJumps, badJumps []*ast.BranchStmt
+	)
+
+	// All forward jumps jumping over a variable declaration are possibly
+	// invalid (they may still jump out of the block and be ok).
+	// recordVarDecl records them for the given position.
+	recordVarDecl := func(pos token.Pos) {
+		varDeclPos = pos
+		badJumps = append(badJumps[:0], fwdJumps...) // copy fwdJumps to badJumps
+	}
+
+	jumpsOverVarDecl := func(jmp *ast.BranchStmt) bool {
+		if varDeclPos.IsValid() {
+			for _, bad := range badJumps {
+				if jmp == bad {
+					return true
+				}
+			}
+		}
+		return false
+	}
+
+	blockBranches := func(lstmt *ast.LabeledStmt, list []ast.Stmt) {
+		// Unresolved forward jumps inside the nested block
+		// become forward jumps in the current block.
+		fwdJumps = append(fwdJumps, check.blockBranches(all, b, lstmt, list)...)
+	}
+
+	var stmtBranches func(ast.Stmt)
+	stmtBranches = func(s ast.Stmt) {
+		switch s := s.(type) {
+		case *ast.DeclStmt:
+			if d, _ := s.Decl.(*ast.GenDecl); d != nil && d.Tok == token.VAR {
+				recordVarDecl(d.Pos())
+			}
+
+		case *ast.LabeledStmt:
+			// declare non-blank label
+			if name := s.Label.Name; name != "_" {
+				lbl := NewLabel(s.Label.Pos(), check.pkg, name)
+				if alt := all.Insert(lbl); alt != nil {
+					check.softErrorf(lbl.pos, "label %s already declared", name)
+					check.reportAltDecl(alt)
+					// ok to continue
+				} else {
+					b.insert(s)
+					check.recordDef(s.Label, lbl)
+				}
+				// resolve matching forward jumps and remove them from fwdJumps
+				i := 0
+				for _, jmp := range fwdJumps {
+					if jmp.Label.Name == name {
+						// match
+						lbl.used = true
+						check.recordUse(jmp.Label, lbl)
+						if jumpsOverVarDecl(jmp) {
+							check.softErrorf(
+								jmp.Label.Pos(),
+								"goto %s jumps over variable declaration at line %d",
+								name,
+								check.fset.Position(varDeclPos).Line,
+							)
+							// ok to continue
+						}
+					} else {
+						// no match - record new forward jump
+						fwdJumps[i] = jmp
+						i++
+					}
+				}
+				fwdJumps = fwdJumps[:i]
+				lstmt = s
+			}
+			stmtBranches(s.Stmt)
+
+		case *ast.BranchStmt:
+			if s.Label == nil {
+				return // checked in 1st pass (check.stmt)
+			}
+
+			// determine and validate target
+			name := s.Label.Name
+			switch s.Tok {
+			case token.BREAK:
+				// spec: "If there is a label, it must be that of an enclosing
+				// "for", "switch", or "select" statement, and that is the one
+				// whose execution terminates."
+				valid := false
+				if t := b.enclosingTarget(name); t != nil {
+					switch t.Stmt.(type) {
+					case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt, *ast.ForStmt, *ast.RangeStmt:
+						valid = true
+					}
+				}
+				if !valid {
+					check.errorf(s.Label.Pos(), "invalid break label %s", name)
+					return
+				}
+
+			case token.CONTINUE:
+				// spec: "If there is a label, it must be that of an enclosing
+				// "for" statement, and that is the one whose execution advances."
+				valid := false
+				if t := b.enclosingTarget(name); t != nil {
+					switch t.Stmt.(type) {
+					case *ast.ForStmt, *ast.RangeStmt:
+						valid = true
+					}
+				}
+				if !valid {
+					check.errorf(s.Label.Pos(), "invalid continue label %s", name)
+					return
+				}
+
+			case token.GOTO:
+				if b.gotoTarget(name) == nil {
+					// label may be declared later - add branch to forward jumps
+					fwdJumps = append(fwdJumps, s)
+					return
+				}
+
+			default:
+				check.invalidAST(s.Pos(), "branch statement: %s %s", s.Tok, name)
+				return
+			}
+
+			// record label use
+			obj := all.Lookup(name)
+			obj.(*Label).used = true
+			check.recordUse(s.Label, obj)
+
+		case *ast.AssignStmt:
+			if s.Tok == token.DEFINE {
+				recordVarDecl(s.Pos())
+			}
+
+		case *ast.BlockStmt:
+			blockBranches(lstmt, s.List)
+
+		case *ast.IfStmt:
+			stmtBranches(s.Body)
+			if s.Else != nil {
+				stmtBranches(s.Else)
+			}
+
+		case *ast.CaseClause:
+			blockBranches(nil, s.Body)
+
+		case *ast.SwitchStmt:
+			stmtBranches(s.Body)
+
+		case *ast.TypeSwitchStmt:
+			stmtBranches(s.Body)
+
+		case *ast.CommClause:
+			blockBranches(nil, s.Body)
+
+		case *ast.SelectStmt:
+			stmtBranches(s.Body)
+
+		case *ast.ForStmt:
+			stmtBranches(s.Body)
+
+		case *ast.RangeStmt:
+			stmtBranches(s.Body)
+		}
+	}
+
+	for _, s := range list {
+		stmtBranches(s)
+	}
+
+	return fwdJumps
+}
diff --git a/libgo/go/go/types/lookup.go b/libgo/go/go/types/lookup.go
new file mode 100644
index 00000000000..3caca5519b6
--- /dev/null
+++ b/libgo/go/go/types/lookup.go
@@ -0,0 +1,341 @@
+// Copyright 2013 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.
+
+// This file implements various field and method lookup functions.
+
+package types
+
+// LookupFieldOrMethod looks up a field or method with given package and name
+// in T and returns the corresponding *Var or *Func, an index sequence, and a
+// bool indicating if there were any pointer indirections on the path to the
+// field or method. If addressable is set, T is the type of an addressable
+// variable (only matters for method lookups).
+//
+// The last index entry is the field or method index in the (possibly embedded)
+// type where the entry was found, either:
+//
+//	1) the list of declared methods of a named type; or
+//	2) the list of all methods (method set) of an interface type; or
+//	3) the list of fields of a struct type.
+//
+// The earlier index entries are the indices of the anonymous struct fields
+// traversed to get to the found entry, starting at depth 0.
+//
+// If no entry is found, a nil object is returned. In this case, the returned
+// index and indirect values have the following meaning:
+//
+//	- If index != nil, the index sequence points to an ambiguous entry
+//	(the same name appeared more than once at the same embedding level).
+//
+//	- If indirect is set, a method with a pointer receiver type was found
+//      but there was no pointer on the path from the actual receiver type to
+//	the method's formal receiver base type, nor was the receiver addressable.
+//
+func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+	// Methods cannot be associated to a named pointer type
+	// (spec: "The type denoted by T is called the receiver base type;
+	// it must not be a pointer or interface type and it must be declared
+	// in the same package as the method.").
+	// Thus, if we have a named pointer type, proceed with the underlying
+	// pointer type but discard the result if it is a method since we would
+	// not have found it for T (see also issue 8590).
+	if t, _ := T.(*Named); t != nil {
+		if p, _ := t.underlying.(*Pointer); p != nil {
+			obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
+			if _, ok := obj.(*Func); ok {
+				return nil, nil, false
+			}
+			return
+		}
+	}
+
+	return lookupFieldOrMethod(T, addressable, pkg, name)
+}
+
+// TODO(gri) The named type consolidation and seen maps below must be
+//           indexed by unique keys for a given type. Verify that named
+//           types always have only one representation (even when imported
+//           indirectly via different packages.)
+
+func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool) {
+	// WARNING: The code in this function is extremely subtle - do not modify casually!
+	//          This function and NewMethodSet should be kept in sync.
+
+	if name == "_" {
+		return // blank fields/methods are never found
+	}
+
+	typ, isPtr := deref(T)
+	named, _ := typ.(*Named)
+
+	// *typ where typ is an interface has no methods.
+	if isPtr {
+		utyp := typ
+		if named != nil {
+			utyp = named.underlying
+		}
+		if _, ok := utyp.(*Interface); ok {
+			return
+		}
+	}
+
+	// Start with typ as single entry at shallowest depth.
+	// If typ is not a named type, insert a nil type instead.
+	current := []embeddedType{{named, nil, isPtr, false}}
+
+	// named types that we have seen already, allocated lazily
+	var seen map[*Named]bool
+
+	// search current depth
+	for len(current) > 0 {
+		var next []embeddedType // embedded types found at current depth
+
+		// look for (pkg, name) in all types at current depth
+		for _, e := range current {
+			// The very first time only, e.typ may be nil.
+			// In this case, we don't have a named type and
+			// we simply continue with the underlying type.
+			if e.typ != nil {
+				if seen[e.typ] {
+					// We have seen this type before, at a more shallow depth
+					// (note that multiples of this type at the current depth
+					// were consolidated before). The type at that depth shadows
+					// this same type at the current depth, so we can ignore
+					// this one.
+					continue
+				}
+				if seen == nil {
+					seen = make(map[*Named]bool)
+				}
+				seen[e.typ] = true
+
+				// look for a matching attached method
+				if i, m := lookupMethod(e.typ.methods, pkg, name); m != nil {
+					// potential match
+					assert(m.typ != nil)
+					index = concat(e.index, i)
+					if obj != nil || e.multiples {
+						return nil, index, false // collision
+					}
+					obj = m
+					indirect = e.indirect
+					continue // we can't have a matching field or interface method
+				}
+
+				// continue with underlying type
+				typ = e.typ.underlying
+			}
+
+			switch t := typ.(type) {
+			case *Struct:
+				// look for a matching field and collect embedded types
+				for i, f := range t.fields {
+					if f.sameId(pkg, name) {
+						assert(f.typ != nil)
+						index = concat(e.index, i)
+						if obj != nil || e.multiples {
+							return nil, index, false // collision
+						}
+						obj = f
+						indirect = e.indirect
+						continue // we can't have a matching interface method
+					}
+					// Collect embedded struct fields for searching the next
+					// lower depth, but only if we have not seen a match yet
+					// (if we have a match it is either the desired field or
+					// we have a name collision on the same depth; in either
+					// case we don't need to look further).
+					// Embedded fields are always of the form T or *T where
+					// T is a named type. If e.typ appeared multiple times at
+					// this depth, f.typ appears multiple times at the next
+					// depth.
+					if obj == nil && f.anonymous {
+						// Ignore embedded basic types - only user-defined
+						// named types can have methods or struct fields.
+						typ, isPtr := deref(f.typ)
+						if t, _ := typ.(*Named); t != nil {
+							next = append(next, embeddedType{t, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						}
+					}
+				}
+
+			case *Interface:
+				// look for a matching method
+				// TODO(gri) t.allMethods is sorted - use binary search
+				if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
+					assert(m.typ != nil)
+					index = concat(e.index, i)
+					if obj != nil || e.multiples {
+						return nil, index, false // collision
+					}
+					obj = m
+					indirect = e.indirect
+				}
+			}
+		}
+
+		if obj != nil {
+			// found a potential match
+			// spec: "A method call x.m() is valid if the method set of (the type of) x
+			//        contains m and the argument list can be assigned to the parameter
+			//        list of m. If x is addressable and &x's method set contains m, x.m()
+			//        is shorthand for (&x).m()".
+			if f, _ := obj.(*Func); f != nil && ptrRecv(f) && !indirect && !addressable {
+				return nil, nil, true // pointer/addressable receiver required
+			}
+			return
+		}
+
+		current = consolidateMultiples(next)
+	}
+
+	return nil, nil, false // not found
+}
+
+// embeddedType represents an embedded named type
+type embeddedType struct {
+	typ       *Named // nil means use the outer typ variable instead
+	index     []int  // embedded field indices, starting with index at depth 0
+	indirect  bool   // if set, there was a pointer indirection on the path to this field
+	multiples bool   // if set, typ appears multiple times at this depth
+}
+
+// consolidateMultiples collects multiple list entries with the same type
+// into a single entry marked as containing multiples. The result is the
+// consolidated list.
+func consolidateMultiples(list []embeddedType) []embeddedType {
+	if len(list) <= 1 {
+		return list // at most one entry - nothing to do
+	}
+
+	n := 0                       // number of entries w/ unique type
+	prev := make(map[*Named]int) // index at which type was previously seen
+	for _, e := range list {
+		if i, found := prev[e.typ]; found {
+			list[i].multiples = true
+			// ignore this entry
+		} else {
+			prev[e.typ] = n
+			list[n] = e
+			n++
+		}
+	}
+	return list[:n]
+}
+
+// MissingMethod returns (nil, false) if V implements T, otherwise it
+// returns a missing method required by T and whether it is missing or
+// just has the wrong type.
+//
+// For non-interface types V, or if static is set, V implements T if all
+// methods of T are present in V. Otherwise (V is an interface and static
+// is not set), MissingMethod only checks that methods of T which are also
+// present in V have matching types (e.g., for a type assertion x.(T) where
+// x is of interface type V).
+//
+func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType bool) {
+	// fast path for common case
+	if T.Empty() {
+		return
+	}
+
+	// TODO(gri) Consider using method sets here. Might be more efficient.
+
+	if ityp, _ := V.Underlying().(*Interface); ityp != nil {
+		// TODO(gri) allMethods is sorted - can do this more efficiently
+		for _, m := range T.allMethods {
+			_, obj := lookupMethod(ityp.allMethods, m.pkg, m.name)
+			switch {
+			case obj == nil:
+				if static {
+					return m, false
+				}
+			case !Identical(obj.Type(), m.typ):
+				return m, true
+			}
+		}
+		return
+	}
+
+	// A concrete type implements T if it implements all methods of T.
+	for _, m := range T.allMethods {
+		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
+
+		f, _ := obj.(*Func)
+		if f == nil {
+			return m, false
+		}
+
+		if !Identical(f.typ, m.typ) {
+			return m, true
+		}
+	}
+
+	return
+}
+
+// assertableTo reports whether a value of type V can be asserted to have type T.
+// It returns (nil, false) as affirmative answer. Otherwise it returns a missing
+// method required by V and whether it is missing or just has the wrong type.
+func assertableTo(V *Interface, T Type) (method *Func, wrongType bool) {
+	// no static check is required if T is an interface
+	// spec: "If T is an interface type, x.(T) asserts that the
+	//        dynamic type of x implements the interface T."
+	if _, ok := T.Underlying().(*Interface); ok && !strict {
+		return
+	}
+	return MissingMethod(T, V, false)
+}
+
+// deref dereferences typ if it is a *Pointer and returns its base and true.
+// Otherwise it returns (typ, false).
+func deref(typ Type) (Type, bool) {
+	if p, _ := typ.(*Pointer); p != nil {
+		return p.base, true
+	}
+	return typ, false
+}
+
+// derefStructPtr dereferences typ if it is a (named or unnamed) pointer to a
+// (named or unnamed) struct and returns its base. Otherwise it returns typ.
+func derefStructPtr(typ Type) Type {
+	if p, _ := typ.Underlying().(*Pointer); p != nil {
+		if _, ok := p.base.Underlying().(*Struct); ok {
+			return p.base
+		}
+	}
+	return typ
+}
+
+// concat returns the result of concatenating list and i.
+// The result does not share its underlying array with list.
+func concat(list []int, i int) []int {
+	var t []int
+	t = append(t, list...)
+	return append(t, i)
+}
+
+// fieldIndex returns the index for the field with matching package and name, or a value < 0.
+func fieldIndex(fields []*Var, pkg *Package, name string) int {
+	if name != "_" {
+		for i, f := range fields {
+			if f.sameId(pkg, name) {
+				return i
+			}
+		}
+	}
+	return -1
+}
+
+// lookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func lookupMethod(methods []*Func, pkg *Package, name string) (int, *Func) {
+	if name != "_" {
+		for i, m := range methods {
+			if m.sameId(pkg, name) {
+				return i, m
+			}
+		}
+	}
+	return -1, nil
+}
diff --git a/libgo/go/go/types/methodset.go b/libgo/go/go/types/methodset.go
new file mode 100644
index 00000000000..b27f2dac34a
--- /dev/null
+++ b/libgo/go/go/types/methodset.go
@@ -0,0 +1,268 @@
+// Copyright 2013 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.
+
+// This file implements method sets.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+)
+
+// A MethodSet is an ordered set of concrete or abstract (interface) methods;
+// a method is a MethodVal selection, and they are ordered by ascending m.Obj().Id().
+// The zero value for a MethodSet is a ready-to-use empty method set.
+type MethodSet struct {
+	list []*Selection
+}
+
+func (s *MethodSet) String() string {
+	if s.Len() == 0 {
+		return "MethodSet {}"
+	}
+
+	var buf bytes.Buffer
+	fmt.Fprintln(&buf, "MethodSet {")
+	for _, f := range s.list {
+		fmt.Fprintf(&buf, "\t%s\n", f)
+	}
+	fmt.Fprintln(&buf, "}")
+	return buf.String()
+}
+
+// Len returns the number of methods in s.
+func (s *MethodSet) Len() int { return len(s.list) }
+
+// At returns the i'th method in s for 0 <= i < s.Len().
+func (s *MethodSet) At(i int) *Selection { return s.list[i] }
+
+// Lookup returns the method with matching package and name, or nil if not found.
+func (s *MethodSet) Lookup(pkg *Package, name string) *Selection {
+	if s.Len() == 0 {
+		return nil
+	}
+
+	key := Id(pkg, name)
+	i := sort.Search(len(s.list), func(i int) bool {
+		m := s.list[i]
+		return m.obj.Id() >= key
+	})
+	if i < len(s.list) {
+		m := s.list[i]
+		if m.obj.Id() == key {
+			return m
+		}
+	}
+	return nil
+}
+
+// Shared empty method set.
+var emptyMethodSet MethodSet
+
+// NewMethodSet returns the method set for the given type T.
+// It always returns a non-nil method set, even if it is empty.
+func NewMethodSet(T Type) *MethodSet {
+	// WARNING: The code in this function is extremely subtle - do not modify casually!
+	//          This function and lookupFieldOrMethod should be kept in sync.
+
+	// method set up to the current depth, allocated lazily
+	var base methodSet
+
+	typ, isPtr := deref(T)
+	named, _ := typ.(*Named)
+
+	// *typ where typ is an interface has no methods.
+	if isPtr {
+		utyp := typ
+		if named != nil {
+			utyp = named.underlying
+		}
+		if _, ok := utyp.(*Interface); ok {
+			return &emptyMethodSet
+		}
+	}
+
+	// Start with typ as single entry at shallowest depth.
+	// If typ is not a named type, insert a nil type instead.
+	current := []embeddedType{{named, nil, isPtr, false}}
+
+	// named types that we have seen already, allocated lazily
+	var seen map[*Named]bool
+
+	// collect methods at current depth
+	for len(current) > 0 {
+		var next []embeddedType // embedded types found at current depth
+
+		// field and method sets at current depth, allocated lazily
+		var fset fieldSet
+		var mset methodSet
+
+		for _, e := range current {
+			// The very first time only, e.typ may be nil.
+			// In this case, we don't have a named type and
+			// we simply continue with the underlying type.
+			if e.typ != nil {
+				if seen[e.typ] {
+					// We have seen this type before, at a more shallow depth
+					// (note that multiples of this type at the current depth
+					// were consolidated before). The type at that depth shadows
+					// this same type at the current depth, so we can ignore
+					// this one.
+					continue
+				}
+				if seen == nil {
+					seen = make(map[*Named]bool)
+				}
+				seen[e.typ] = true
+
+				mset = mset.add(e.typ.methods, e.index, e.indirect, e.multiples)
+
+				// continue with underlying type
+				typ = e.typ.underlying
+			}
+
+			switch t := typ.(type) {
+			case *Struct:
+				for i, f := range t.fields {
+					fset = fset.add(f, e.multiples)
+
+					// Embedded fields are always of the form T or *T where
+					// T is a named type. If typ appeared multiple times at
+					// this depth, f.Type appears multiple times at the next
+					// depth.
+					if f.anonymous {
+						// Ignore embedded basic types - only user-defined
+						// named types can have methods or struct fields.
+						typ, isPtr := deref(f.typ)
+						if t, _ := typ.(*Named); t != nil {
+							next = append(next, embeddedType{t, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						}
+					}
+				}
+
+			case *Interface:
+				mset = mset.add(t.allMethods, e.index, true, e.multiples)
+			}
+		}
+
+		// Add methods and collisions at this depth to base if no entries with matching
+		// names exist already.
+		for k, m := range mset {
+			if _, found := base[k]; !found {
+				// Fields collide with methods of the same name at this depth.
+				if _, found := fset[k]; found {
+					m = nil // collision
+				}
+				if base == nil {
+					base = make(methodSet)
+				}
+				base[k] = m
+			}
+		}
+
+		// Multiple fields with matching names collide at this depth and shadow all
+		// entries further down; add them as collisions to base if no entries with
+		// matching names exist already.
+		for k, f := range fset {
+			if f == nil {
+				if _, found := base[k]; !found {
+					if base == nil {
+						base = make(methodSet)
+					}
+					base[k] = nil // collision
+				}
+			}
+		}
+
+		current = consolidateMultiples(next)
+	}
+
+	if len(base) == 0 {
+		return &emptyMethodSet
+	}
+
+	// collect methods
+	var list []*Selection
+	for _, m := range base {
+		if m != nil {
+			m.recv = T
+			list = append(list, m)
+		}
+	}
+	sort.Sort(byUniqueName(list))
+	return &MethodSet{list}
+}
+
+// A fieldSet is a set of fields and name collisions.
+// A collision indicates that multiple fields with the
+// same unique id appeared.
+type fieldSet map[string]*Var // a nil entry indicates a name collision
+
+// Add adds field f to the field set s.
+// If multiples is set, f appears multiple times
+// and is treated as a collision.
+func (s fieldSet) add(f *Var, multiples bool) fieldSet {
+	if s == nil {
+		s = make(fieldSet)
+	}
+	key := f.Id()
+	// if f is not in the set, add it
+	if !multiples {
+		if _, found := s[key]; !found {
+			s[key] = f
+			return s
+		}
+	}
+	s[key] = nil // collision
+	return s
+}
+
+// A methodSet is a set of methods and name collisions.
+// A collision indicates that multiple methods with the
+// same unique id appeared.
+type methodSet map[string]*Selection // a nil entry indicates a name collision
+
+// Add adds all functions in list to the method set s.
+// If multiples is set, every function in list appears multiple times
+// and is treated as a collision.
+func (s methodSet) add(list []*Func, index []int, indirect bool, multiples bool) methodSet {
+	if len(list) == 0 {
+		return s
+	}
+	if s == nil {
+		s = make(methodSet)
+	}
+	for i, f := range list {
+		key := f.Id()
+		// if f is not in the set, add it
+		if !multiples {
+			// TODO(gri) A found method may not be added because it's not in the method set
+			// (!indirect && ptrRecv(f)). A 2nd method on the same level may be in the method
+			// set and may not collide with the first one, thus leading to a false positive.
+			// Is that possible? Investigate.
+			if _, found := s[key]; !found && (indirect || !ptrRecv(f)) {
+				s[key] = &Selection{MethodVal, nil, f, concat(index, i), indirect}
+				continue
+			}
+		}
+		s[key] = nil // collision
+	}
+	return s
+}
+
+// ptrRecv reports whether the receiver is of the form *T.
+// The receiver must exist.
+func ptrRecv(f *Func) bool {
+	_, isPtr := deref(f.typ.(*Signature).recv.typ)
+	return isPtr
+}
+
+// byUniqueName function lists can be sorted by their unique names.
+type byUniqueName []*Selection
+
+func (a byUniqueName) Len() int           { return len(a) }
+func (a byUniqueName) Less(i, j int) bool { return a[i].obj.Id() < a[j].obj.Id() }
+func (a byUniqueName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
diff --git a/libgo/go/go/types/object.go b/libgo/go/go/types/object.go
new file mode 100644
index 00000000000..b835c6e53e8
--- /dev/null
+++ b/libgo/go/go/types/object.go
@@ -0,0 +1,360 @@
+// Copyright 2013 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 types
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+// TODO(gri) Document factory, accessor methods, and fields. General clean-up.
+
+// An Object describes a named language entity such as a package,
+// constant, type, variable, function (incl. methods), or label.
+// All objects implement the Object interface.
+//
+type Object interface {
+	Parent() *Scope // scope in which this object is declared
+	Pos() token.Pos // position of object identifier in declaration
+	Pkg() *Package  // nil for objects in the Universe scope and labels
+	Name() string   // package local object name
+	Type() Type     // object type
+	Exported() bool // reports whether the name starts with a capital letter
+	Id() string     // object id (see Id below)
+
+	// String returns a human-readable string of the object.
+	String() string
+
+	// order reflects a package-level object's source order: if object
+	// a is before object b in the source, then a.order() < b.order().
+	// order returns a value > 0 for package-level objects; it returns
+	// 0 for all other objects (including objects in file scopes).
+	order() uint32
+
+	// setOrder sets the order number of the object. It must be > 0.
+	setOrder(uint32)
+
+	// setParent sets the parent scope of the object.
+	setParent(*Scope)
+
+	// sameId reports whether obj.Id() and Id(pkg, name) are the same.
+	sameId(pkg *Package, name string) bool
+
+	// scopePos returns the start position of the scope of this Object
+	scopePos() token.Pos
+
+	// setScopePos sets the start position of the scope for this Object.
+	setScopePos(pos token.Pos)
+}
+
+// Id returns name if it is exported, otherwise it
+// returns the name qualified with the package path.
+func Id(pkg *Package, name string) string {
+	if ast.IsExported(name) {
+		return name
+	}
+	// unexported names need the package path for differentiation
+	// (if there's no package, make sure we don't start with '.'
+	// as that may change the order of methods between a setup
+	// inside a package and outside a package - which breaks some
+	// tests)
+	path := "_"
+	// TODO(gri): shouldn't !ast.IsExported(name) => pkg != nil be an precondition?
+	// if pkg == nil {
+	// 	panic("nil package in lookup of unexported name")
+	// }
+	if pkg != nil {
+		path = pkg.path
+		if path == "" {
+			path = "_"
+		}
+	}
+	return path + "." + name
+}
+
+// An object implements the common parts of an Object.
+type object struct {
+	parent    *Scope
+	pos       token.Pos
+	pkg       *Package
+	name      string
+	typ       Type
+	order_    uint32
+	scopePos_ token.Pos
+}
+
+func (obj *object) Parent() *Scope      { return obj.parent }
+func (obj *object) Pos() token.Pos      { return obj.pos }
+func (obj *object) Pkg() *Package       { return obj.pkg }
+func (obj *object) Name() string        { return obj.name }
+func (obj *object) Type() Type          { return obj.typ }
+func (obj *object) Exported() bool      { return ast.IsExported(obj.name) }
+func (obj *object) Id() string          { return Id(obj.pkg, obj.name) }
+func (obj *object) String() string      { panic("abstract") }
+func (obj *object) order() uint32       { return obj.order_ }
+func (obj *object) scopePos() token.Pos { return obj.scopePos_ }
+
+func (obj *object) setParent(parent *Scope)   { obj.parent = parent }
+func (obj *object) setOrder(order uint32)     { assert(order > 0); obj.order_ = order }
+func (obj *object) setScopePos(pos token.Pos) { obj.scopePos_ = pos }
+
+func (obj *object) sameId(pkg *Package, name string) bool {
+	// spec:
+	// "Two identifiers are different if they are spelled differently,
+	// or if they appear in different packages and are not exported.
+	// Otherwise, they are the same."
+	if name != obj.name {
+		return false
+	}
+	// obj.Name == name
+	if obj.Exported() {
+		return true
+	}
+	// not exported, so packages must be the same (pkg == nil for
+	// fields in Universe scope; this can only happen for types
+	// introduced via Eval)
+	if pkg == nil || obj.pkg == nil {
+		return pkg == obj.pkg
+	}
+	// pkg != nil && obj.pkg != nil
+	return pkg.path == obj.pkg.path
+}
+
+// A PkgName represents an imported Go package.
+type PkgName struct {
+	object
+	imported *Package
+	used     bool // set if the package was used
+}
+
+func NewPkgName(pos token.Pos, pkg *Package, name string, imported *Package) *PkgName {
+	return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, token.NoPos}, imported, false}
+}
+
+// Imported returns the package that was imported.
+// It is distinct from Pkg(), which is the package containing the import statement.
+func (obj *PkgName) Imported() *Package { return obj.imported }
+
+// A Const represents a declared constant.
+type Const struct {
+	object
+	val     constant.Value
+	visited bool // for initialization cycle detection
+}
+
+func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const {
+	return &Const{object{nil, pos, pkg, name, typ, 0, token.NoPos}, val, false}
+}
+
+func (obj *Const) Val() constant.Value { return obj.val }
+
+// A TypeName represents a declared type.
+type TypeName struct {
+	object
+}
+
+func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
+	return &TypeName{object{nil, pos, pkg, name, typ, 0, token.NoPos}}
+}
+
+// A Variable represents a declared variable (including function parameters and results, and struct fields).
+type Var struct {
+	object
+	anonymous bool // if set, the variable is an anonymous struct field, and name is the type name
+	visited   bool // for initialization cycle detection
+	isField   bool // var is struct field
+	used      bool // set if the variable was used
+}
+
+func NewVar(pos token.Pos, pkg *Package, name string, typ Type) *Var {
+	return &Var{object: object{nil, pos, pkg, name, typ, 0, token.NoPos}}
+}
+
+func NewParam(pos token.Pos, pkg *Package, name string, typ Type) *Var {
+	return &Var{object: object{nil, pos, pkg, name, typ, 0, token.NoPos}, used: true} // parameters are always 'used'
+}
+
+func NewField(pos token.Pos, pkg *Package, name string, typ Type, anonymous bool) *Var {
+	return &Var{object: object{nil, pos, pkg, name, typ, 0, token.NoPos}, anonymous: anonymous, isField: true}
+}
+
+func (obj *Var) Anonymous() bool { return obj.anonymous }
+
+func (obj *Var) IsField() bool { return obj.isField }
+
+// A Func represents a declared function, concrete method, or abstract
+// (interface) method.  Its Type() is always a *Signature.
+// An abstract method may belong to many interfaces due to embedding.
+type Func struct {
+	object
+}
+
+func NewFunc(pos token.Pos, pkg *Package, name string, sig *Signature) *Func {
+	// don't store a nil signature
+	var typ Type
+	if sig != nil {
+		typ = sig
+	}
+	return &Func{object{nil, pos, pkg, name, typ, 0, token.NoPos}}
+}
+
+// FullName returns the package- or receiver-type-qualified name of
+// function or method obj.
+func (obj *Func) FullName() string {
+	var buf bytes.Buffer
+	writeFuncName(&buf, obj, nil)
+	return buf.String()
+}
+
+func (obj *Func) Scope() *Scope {
+	return obj.typ.(*Signature).scope
+}
+
+// A Label represents a declared label.
+type Label struct {
+	object
+	used bool // set if the label was used
+}
+
+func NewLabel(pos token.Pos, pkg *Package, name string) *Label {
+	return &Label{object{pos: pos, pkg: pkg, name: name, typ: Typ[Invalid]}, false}
+}
+
+// A Builtin represents a built-in function.
+// Builtins don't have a valid type.
+type Builtin struct {
+	object
+	id builtinId
+}
+
+func newBuiltin(id builtinId) *Builtin {
+	return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid]}, id}
+}
+
+// Nil represents the predeclared value nil.
+type Nil struct {
+	object
+}
+
+func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
+	typ := obj.Type()
+	switch obj := obj.(type) {
+	case *PkgName:
+		fmt.Fprintf(buf, "package %s", obj.Name())
+		if path := obj.imported.path; path != "" && path != obj.name {
+			fmt.Fprintf(buf, " (%q)", path)
+		}
+		return
+
+	case *Const:
+		buf.WriteString("const")
+
+	case *TypeName:
+		buf.WriteString("type")
+		typ = typ.Underlying()
+
+	case *Var:
+		if obj.isField {
+			buf.WriteString("field")
+		} else {
+			buf.WriteString("var")
+		}
+
+	case *Func:
+		buf.WriteString("func ")
+		writeFuncName(buf, obj, qf)
+		if typ != nil {
+			WriteSignature(buf, typ.(*Signature), qf)
+		}
+		return
+
+	case *Label:
+		buf.WriteString("label")
+		typ = nil
+
+	case *Builtin:
+		buf.WriteString("builtin")
+		typ = nil
+
+	case *Nil:
+		buf.WriteString("nil")
+		return
+
+	default:
+		panic(fmt.Sprintf("writeObject(%T)", obj))
+	}
+
+	buf.WriteByte(' ')
+
+	// For package-level objects, qualify the name.
+	if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
+		writePackage(buf, obj.Pkg(), qf)
+	}
+	buf.WriteString(obj.Name())
+	if typ != nil {
+		buf.WriteByte(' ')
+		WriteType(buf, typ, qf)
+	}
+}
+
+func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
+	if pkg == nil {
+		return
+	}
+	var s string
+	if qf != nil {
+		s = qf(pkg)
+	} else {
+		s = pkg.Path()
+	}
+	if s != "" {
+		buf.WriteString(s)
+		buf.WriteByte('.')
+	}
+}
+
+// ObjectString returns the string form of obj.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func ObjectString(obj Object, qf Qualifier) string {
+	var buf bytes.Buffer
+	writeObject(&buf, obj, qf)
+	return buf.String()
+}
+
+func (obj *PkgName) String() string  { return ObjectString(obj, nil) }
+func (obj *Const) String() string    { return ObjectString(obj, nil) }
+func (obj *TypeName) String() string { return ObjectString(obj, nil) }
+func (obj *Var) String() string      { return ObjectString(obj, nil) }
+func (obj *Func) String() string     { return ObjectString(obj, nil) }
+func (obj *Label) String() string    { return ObjectString(obj, nil) }
+func (obj *Builtin) String() string  { return ObjectString(obj, nil) }
+func (obj *Nil) String() string      { return ObjectString(obj, nil) }
+
+func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
+	if f.typ != nil {
+		sig := f.typ.(*Signature)
+		if recv := sig.Recv(); recv != nil {
+			buf.WriteByte('(')
+			if _, ok := recv.Type().(*Interface); ok {
+				// gcimporter creates abstract methods of
+				// named interfaces using the interface type
+				// (not the named type) as the receiver.
+				// Don't print it in full.
+				buf.WriteString("interface")
+			} else {
+				WriteType(buf, recv.Type(), qf)
+			}
+			buf.WriteByte(')')
+			buf.WriteByte('.')
+		} else if f.pkg != nil {
+			writePackage(buf, f.pkg, qf)
+		}
+	}
+	buf.WriteString(f.name)
+}
diff --git a/libgo/go/go/types/objset.go b/libgo/go/go/types/objset.go
new file mode 100644
index 00000000000..55eb74addba
--- /dev/null
+++ b/libgo/go/go/types/objset.go
@@ -0,0 +1,31 @@
+// Copyright 2013 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.
+
+// This file implements objsets.
+//
+// An objset is similar to a Scope but objset elements
+// are identified by their unique id, instead of their
+// object name.
+
+package types
+
+// An objset is a set of objects identified by their unique id.
+// The zero value for objset is a ready-to-use empty objset.
+type objset map[string]Object // initialized lazily
+
+// insert attempts to insert an object obj into objset s.
+// If s already contains an alternative object alt with
+// the same name, insert leaves s unchanged and returns alt.
+// Otherwise it inserts obj and returns nil.
+func (s *objset) insert(obj Object) Object {
+	id := obj.Id()
+	if alt := (*s)[id]; alt != nil {
+		return alt
+	}
+	if *s == nil {
+		*s = make(map[string]Object)
+	}
+	(*s)[id] = obj
+	return nil
+}
diff --git a/libgo/go/go/types/operand.go b/libgo/go/go/types/operand.go
new file mode 100644
index 00000000000..d3bab51b04a
--- /dev/null
+++ b/libgo/go/go/types/operand.go
@@ -0,0 +1,287 @@
+// 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.
+
+// This file defines operands and associated operations.
+
+package types
+
+import (
+	"bytes"
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+// An operandMode specifies the (addressing) mode of an operand.
+type operandMode byte
+
+const (
+	invalid   operandMode = iota // operand is invalid
+	novalue                      // operand represents no value (result of a function call w/o result)
+	builtin                      // operand is a built-in function
+	typexpr                      // operand is a type
+	constant_                    // operand is a constant; the operand's typ is a Basic type
+	variable                     // operand is an addressable variable
+	mapindex                     // operand is a map index expression (acts like a variable on lhs, commaok on rhs of an assignment)
+	value                        // operand is a computed value
+	commaok                      // like value, but operand may be used in a comma,ok expression
+)
+
+var operandModeString = [...]string{
+	invalid:   "invalid operand",
+	novalue:   "no value",
+	builtin:   "built-in",
+	typexpr:   "type",
+	constant_: "constant",
+	variable:  "variable",
+	mapindex:  "map index expression",
+	value:     "value",
+	commaok:   "comma, ok expression",
+}
+
+// An operand represents an intermediate value during type checking.
+// Operands have an (addressing) mode, the expression evaluating to
+// the operand, the operand's type, a value for constants, and an id
+// for built-in functions.
+// The zero value of operand is a ready to use invalid operand.
+//
+type operand struct {
+	mode operandMode
+	expr ast.Expr
+	typ  Type
+	val  constant.Value
+	id   builtinId
+}
+
+// pos returns the position of the expression corresponding to x.
+// If x is invalid the position is token.NoPos.
+//
+func (x *operand) pos() token.Pos {
+	// x.expr may not be set if x is invalid
+	if x.expr == nil {
+		return token.NoPos
+	}
+	return x.expr.Pos()
+}
+
+// Operand string formats
+// (not all "untyped" cases can appear due to the type system,
+// but they fall out naturally here)
+//
+// mode       format
+//
+// invalid    <expr> (               <mode>                    )
+// novalue    <expr> (               <mode>                    )
+// builtin    <expr> (               <mode>                    )
+// typexpr    <expr> (               <mode>                    )
+//
+// constant   <expr> (<untyped kind> <mode>                    )
+// constant   <expr> (               <mode>       of type <typ>)
+// constant   <expr> (<untyped kind> <mode> <val>              )
+// constant   <expr> (               <mode> <val> of type <typ>)
+//
+// variable   <expr> (<untyped kind> <mode>                    )
+// variable   <expr> (               <mode>       of type <typ>)
+//
+// mapindex   <expr> (<untyped kind> <mode>                    )
+// mapindex   <expr> (               <mode>       of type <typ>)
+//
+// value      <expr> (<untyped kind> <mode>                    )
+// value      <expr> (               <mode>       of type <typ>)
+//
+// commaok    <expr> (<untyped kind> <mode>                    )
+// commaok    <expr> (               <mode>       of type <typ>)
+//
+func operandString(x *operand, qf Qualifier) string {
+	var buf bytes.Buffer
+
+	var expr string
+	if x.expr != nil {
+		expr = ExprString(x.expr)
+	} else {
+		switch x.mode {
+		case builtin:
+			expr = predeclaredFuncs[x.id].name
+		case typexpr:
+			expr = TypeString(x.typ, qf)
+		case constant_:
+			expr = x.val.String()
+		}
+	}
+
+	// <expr> (
+	if expr != "" {
+		buf.WriteString(expr)
+		buf.WriteString(" (")
+	}
+
+	// <untyped kind>
+	hasType := false
+	switch x.mode {
+	case invalid, novalue, builtin, typexpr:
+		// no type
+	default:
+		// has type
+		if isUntyped(x.typ) {
+			buf.WriteString(x.typ.(*Basic).name)
+			buf.WriteByte(' ')
+			break
+		}
+		hasType = true
+	}
+
+	// <mode>
+	buf.WriteString(operandModeString[x.mode])
+
+	// <val>
+	if x.mode == constant_ {
+		if s := x.val.String(); s != expr {
+			buf.WriteByte(' ')
+			buf.WriteString(s)
+		}
+	}
+
+	// <typ>
+	if hasType {
+		if x.typ != Typ[Invalid] {
+			buf.WriteString(" of type ")
+			WriteType(&buf, x.typ, qf)
+		} else {
+			buf.WriteString(" with invalid type")
+		}
+	}
+
+	// )
+	if expr != "" {
+		buf.WriteByte(')')
+	}
+
+	return buf.String()
+}
+
+func (x *operand) String() string {
+	return operandString(x, nil)
+}
+
+// setConst sets x to the untyped constant for literal lit.
+func (x *operand) setConst(tok token.Token, lit string) {
+	val := constant.MakeFromLiteral(lit, tok, 0)
+	if val == nil {
+		// TODO(gri) Should we make it an unknown constant instead?
+		x.mode = invalid
+		return
+	}
+
+	var kind BasicKind
+	switch tok {
+	case token.INT:
+		kind = UntypedInt
+	case token.FLOAT:
+		kind = UntypedFloat
+	case token.IMAG:
+		kind = UntypedComplex
+	case token.CHAR:
+		kind = UntypedRune
+	case token.STRING:
+		kind = UntypedString
+	}
+
+	x.mode = constant_
+	x.typ = Typ[kind]
+	x.val = val
+}
+
+// isNil reports whether x is the nil value.
+func (x *operand) isNil() bool {
+	return x.mode == value && x.typ == Typ[UntypedNil]
+}
+
+// TODO(gri) The functions operand.assignableTo, checker.convertUntyped,
+//           checker.representable, and checker.assignment are
+//           overlapping in functionality. Need to simplify and clean up.
+
+// assignableTo reports whether x is assignable to a variable of type T.
+func (x *operand) assignableTo(conf *Config, T Type) bool {
+	if x.mode == invalid || T == Typ[Invalid] {
+		return true // avoid spurious errors
+	}
+
+	V := x.typ
+
+	// x's type is identical to T
+	if Identical(V, T) {
+		return true
+	}
+
+	Vu := V.Underlying()
+	Tu := T.Underlying()
+
+	// T is an interface type and x implements T
+	// (Do this check first as it might succeed early.)
+	if Ti, ok := Tu.(*Interface); ok {
+		if Implements(x.typ, Ti) {
+			return true
+		}
+	}
+
+	// x's type V and T have identical underlying types
+	// and at least one of V or T is not a named type
+	if Identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
+		return true
+	}
+
+	// x is a bidirectional channel value, T is a channel
+	// type, x's type V and T have identical element types,
+	// and at least one of V or T is not a named type
+	if Vc, ok := Vu.(*Chan); ok && Vc.dir == SendRecv {
+		if Tc, ok := Tu.(*Chan); ok && Identical(Vc.elem, Tc.elem) {
+			return !isNamed(V) || !isNamed(T)
+		}
+	}
+
+	// x is the predeclared identifier nil and T is a pointer,
+	// function, slice, map, channel, or interface type
+	if x.isNil() {
+		switch t := Tu.(type) {
+		case *Basic:
+			if t.kind == UnsafePointer {
+				return true
+			}
+		case *Pointer, *Signature, *Slice, *Map, *Chan, *Interface:
+			return true
+		}
+		return false
+	}
+
+	// x is an untyped constant representable by a value of type T
+	// TODO(gri) This is borrowing from checker.convertUntyped and
+	//           checker.representable. Need to clean up.
+	if isUntyped(Vu) {
+		switch t := Tu.(type) {
+		case *Basic:
+			if x.mode == constant_ {
+				return representableConst(x.val, conf, t.kind, nil)
+			}
+			// The result of a comparison is an untyped boolean,
+			// but may not be a constant.
+			if Vb, _ := Vu.(*Basic); Vb != nil {
+				return Vb.kind == UntypedBool && isBoolean(Tu)
+			}
+		case *Interface:
+			return x.isNil() || t.Empty()
+		case *Pointer, *Signature, *Slice, *Map, *Chan:
+			return x.isNil()
+		}
+	}
+
+	return false
+}
+
+// isInteger reports whether x is value of integer type
+// or an untyped constant representable as an integer.
+func (x *operand) isInteger() bool {
+	return x.mode == invalid ||
+		isInteger(x.typ) ||
+		isUntyped(x.typ) && x.mode == constant_ && representableConst(x.val, nil, UntypedInt, nil) // no *Config required for UntypedInt
+}
diff --git a/libgo/go/go/types/ordering.go b/libgo/go/go/types/ordering.go
new file mode 100644
index 00000000000..6bb98f2dc10
--- /dev/null
+++ b/libgo/go/go/types/ordering.go
@@ -0,0 +1,127 @@
+// Copyright 2014 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.
+
+// This file implements resolveOrder.
+
+package types
+
+import (
+	"go/ast"
+	"sort"
+)
+
+// resolveOrder computes the order in which package-level objects
+// must be type-checked.
+//
+// Interface types appear first in the list, sorted topologically
+// by dependencies on embedded interfaces that are also declared
+// in this package, followed by all other objects sorted in source
+// order.
+//
+// TODO(gri) Consider sorting all types by dependencies here, and
+// in the process check _and_ report type cycles. This may simplify
+// the full type-checking phase.
+//
+func (check *Checker) resolveOrder() []Object {
+	var ifaces, others []Object
+
+	// collect interface types with their dependencies, and all other objects
+	for obj := range check.objMap {
+		if ityp := check.interfaceFor(obj); ityp != nil {
+			ifaces = append(ifaces, obj)
+			// determine dependencies on embedded interfaces
+			for _, f := range ityp.Methods.List {
+				if len(f.Names) == 0 {
+					// Embedded interface: The type must be a (possibly
+					// qualified) identifier denoting another interface.
+					// Imported interfaces are already fully resolved,
+					// so we can ignore qualified identifiers.
+					if ident, _ := f.Type.(*ast.Ident); ident != nil {
+						embedded := check.pkg.scope.Lookup(ident.Name)
+						if check.interfaceFor(embedded) != nil {
+							check.objMap[obj].addDep(embedded)
+						}
+					}
+				}
+			}
+		} else {
+			others = append(others, obj)
+		}
+	}
+
+	// final object order
+	var order []Object
+
+	// sort interface types topologically by dependencies,
+	// and in source order if there are no dependencies
+	sort.Sort(inSourceOrder(ifaces))
+	if debug {
+		for _, obj := range ifaces {
+			assert(check.objMap[obj].mark == 0)
+		}
+	}
+	for _, obj := range ifaces {
+		check.appendInPostOrder(&order, obj)
+	}
+
+	// sort everything else in source order
+	sort.Sort(inSourceOrder(others))
+
+	return append(order, others...)
+}
+
+// interfaceFor returns the AST interface denoted by obj, or nil.
+func (check *Checker) interfaceFor(obj Object) *ast.InterfaceType {
+	tname, _ := obj.(*TypeName)
+	if tname == nil {
+		return nil // not a type
+	}
+	d := check.objMap[obj]
+	if d == nil {
+		check.dump("%s: %s should have been declared", obj.Pos(), obj.Name())
+		unreachable()
+	}
+	if d.typ == nil {
+		return nil // invalid AST - ignore (will be handled later)
+	}
+	ityp, _ := d.typ.(*ast.InterfaceType)
+	return ityp
+}
+
+func (check *Checker) appendInPostOrder(order *[]Object, obj Object) {
+	d := check.objMap[obj]
+	if d.mark != 0 {
+		// We've already seen this object; either because it's
+		// already added to order, or because we have a cycle.
+		// In both cases we stop. Cycle errors are reported
+		// when type-checking types.
+		return
+	}
+	d.mark = 1
+
+	for _, obj := range orderedSetObjects(d.deps) {
+		check.appendInPostOrder(order, obj)
+	}
+
+	*order = append(*order, obj)
+}
+
+func orderedSetObjects(set map[Object]bool) []Object {
+	list := make([]Object, len(set))
+	i := 0
+	for obj := range set {
+		// we don't care about the map element value
+		list[i] = obj
+		i++
+	}
+	sort.Sort(inSourceOrder(list))
+	return list
+}
+
+// inSourceOrder implements the sort.Sort interface.
+type inSourceOrder []Object
+
+func (a inSourceOrder) Len() int           { return len(a) }
+func (a inSourceOrder) Less(i, j int) bool { return a[i].order() < a[j].order() }
+func (a inSourceOrder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
diff --git a/libgo/go/go/types/package.go b/libgo/go/go/types/package.go
new file mode 100644
index 00000000000..48fe8398fe6
--- /dev/null
+++ b/libgo/go/go/types/package.go
@@ -0,0 +1,65 @@
+// Copyright 2013 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 types
+
+import (
+	"fmt"
+	"go/token"
+)
+
+// A Package describes a Go package.
+type Package struct {
+	path     string
+	name     string
+	scope    *Scope
+	complete bool
+	imports  []*Package
+	fake     bool // scope lookup errors are silently dropped if package is fake (internal use only)
+}
+
+// NewPackage returns a new Package for the given package path and name;
+// the name must not be the blank identifier.
+// The package is not complete and contains no explicit imports.
+func NewPackage(path, name string) *Package {
+	if name == "_" {
+		panic("invalid package name _")
+	}
+	scope := NewScope(Universe, token.NoPos, token.NoPos, fmt.Sprintf("package %q", path))
+	return &Package{path: path, name: name, scope: scope}
+}
+
+// Path returns the package path.
+func (pkg *Package) Path() string { return pkg.path }
+
+// Name returns the package name.
+func (pkg *Package) Name() string { return pkg.name }
+
+// Scope returns the (complete or incomplete) package scope
+// holding the objects declared at package level (TypeNames,
+// Consts, Vars, and Funcs).
+func (pkg *Package) Scope() *Scope { return pkg.scope }
+
+// A package is complete if its scope contains (at least) all
+// exported objects; otherwise it is incomplete.
+func (pkg *Package) Complete() bool { return pkg.complete }
+
+// MarkComplete marks a package as complete.
+func (pkg *Package) MarkComplete() { pkg.complete = true }
+
+// Imports returns the list of packages directly imported by
+// pkg; the list is in source order. Package unsafe is excluded.
+//
+// If pkg was loaded from export data, Imports includes packages that
+// provide package-level objects referenced by pkg.  This may be more or
+// less than the set of packages directly imported by pkg's source code.
+func (pkg *Package) Imports() []*Package { return pkg.imports }
+
+// SetImports sets the list of explicitly imported packages to list.
+// It is the caller's responsibility to make sure list elements are unique.
+func (pkg *Package) SetImports(list []*Package) { pkg.imports = list }
+
+func (pkg *Package) String() string {
+	return fmt.Sprintf("package %s (%q)", pkg.name, pkg.path)
+}
diff --git a/libgo/go/go/types/predicates.go b/libgo/go/go/types/predicates.go
new file mode 100644
index 00000000000..993c6d290b1
--- /dev/null
+++ b/libgo/go/go/types/predicates.go
@@ -0,0 +1,309 @@
+// 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.
+
+// This file implements commonly used type predicates.
+
+package types
+
+import "sort"
+
+func isNamed(typ Type) bool {
+	if _, ok := typ.(*Basic); ok {
+		return ok
+	}
+	_, ok := typ.(*Named)
+	return ok
+}
+
+func isBoolean(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsBoolean != 0
+}
+
+func isInteger(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsInteger != 0
+}
+
+func isUnsigned(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsUnsigned != 0
+}
+
+func isFloat(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsFloat != 0
+}
+
+func isComplex(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsComplex != 0
+}
+
+func isNumeric(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsNumeric != 0
+}
+
+func isString(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsString != 0
+}
+
+func isTyped(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return !ok || t.info&IsUntyped == 0
+}
+
+func isUntyped(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsUntyped != 0
+}
+
+func isOrdered(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsOrdered != 0
+}
+
+func isConstType(typ Type) bool {
+	t, ok := typ.Underlying().(*Basic)
+	return ok && t.info&IsConstType != 0
+}
+
+// IsInterface reports whether typ is an interface type.
+func IsInterface(typ Type) bool {
+	_, ok := typ.Underlying().(*Interface)
+	return ok
+}
+
+// Comparable reports whether values of type T are comparable.
+func Comparable(T Type) bool {
+	switch t := T.Underlying().(type) {
+	case *Basic:
+		// assume invalid types to be comparable
+		// to avoid follow-up errors
+		return t.kind != UntypedNil
+	case *Pointer, *Interface, *Chan:
+		return true
+	case *Struct:
+		for _, f := range t.fields {
+			if !Comparable(f.typ) {
+				return false
+			}
+		}
+		return true
+	case *Array:
+		return Comparable(t.elem)
+	}
+	return false
+}
+
+// hasNil reports whether a type includes the nil value.
+func hasNil(typ Type) bool {
+	switch t := typ.Underlying().(type) {
+	case *Basic:
+		return t.kind == UnsafePointer
+	case *Slice, *Pointer, *Signature, *Interface, *Map, *Chan:
+		return true
+	}
+	return false
+}
+
+// Identical reports whether x and y are identical.
+func Identical(x, y Type) bool {
+	return identical(x, y, nil)
+}
+
+// An ifacePair is a node in a stack of interface type pairs compared for identity.
+type ifacePair struct {
+	x, y *Interface
+	prev *ifacePair
+}
+
+func (p *ifacePair) identical(q *ifacePair) bool {
+	return p.x == q.x && p.y == q.y || p.x == q.y && p.y == q.x
+}
+
+func identical(x, y Type, p *ifacePair) bool {
+	if x == y {
+		return true
+	}
+
+	switch x := x.(type) {
+	case *Basic:
+		// Basic types are singletons except for the rune and byte
+		// aliases, thus we cannot solely rely on the x == y check
+		// above.
+		if y, ok := y.(*Basic); ok {
+			return x.kind == y.kind
+		}
+
+	case *Array:
+		// Two array types are identical if they have identical element types
+		// and the same array length.
+		if y, ok := y.(*Array); ok {
+			return x.len == y.len && identical(x.elem, y.elem, p)
+		}
+
+	case *Slice:
+		// Two slice types are identical if they have identical element types.
+		if y, ok := y.(*Slice); ok {
+			return identical(x.elem, y.elem, p)
+		}
+
+	case *Struct:
+		// Two struct types are identical if they have the same sequence of fields,
+		// and if corresponding fields have the same names, and identical types,
+		// and identical tags. Two anonymous fields are considered to have the same
+		// name. Lower-case field names from different packages are always different.
+		if y, ok := y.(*Struct); ok {
+			if x.NumFields() == y.NumFields() {
+				for i, f := range x.fields {
+					g := y.fields[i]
+					if f.anonymous != g.anonymous ||
+						x.Tag(i) != y.Tag(i) ||
+						!f.sameId(g.pkg, g.name) ||
+						!identical(f.typ, g.typ, p) {
+						return false
+					}
+				}
+				return true
+			}
+		}
+
+	case *Pointer:
+		// Two pointer types are identical if they have identical base types.
+		if y, ok := y.(*Pointer); ok {
+			return identical(x.base, y.base, p)
+		}
+
+	case *Tuple:
+		// Two tuples types are identical if they have the same number of elements
+		// and corresponding elements have identical types.
+		if y, ok := y.(*Tuple); ok {
+			if x.Len() == y.Len() {
+				if x != nil {
+					for i, v := range x.vars {
+						w := y.vars[i]
+						if !identical(v.typ, w.typ, p) {
+							return false
+						}
+					}
+				}
+				return true
+			}
+		}
+
+	case *Signature:
+		// Two function types are identical if they have the same number of parameters
+		// and result values, corresponding parameter and result types are identical,
+		// and either both functions are variadic or neither is. Parameter and result
+		// names are not required to match.
+		if y, ok := y.(*Signature); ok {
+			return x.variadic == y.variadic &&
+				identical(x.params, y.params, p) &&
+				identical(x.results, y.results, p)
+		}
+
+	case *Interface:
+		// Two interface types are identical if they have the same set of methods with
+		// the same names and identical function types. Lower-case method names from
+		// different packages are always different. The order of the methods is irrelevant.
+		if y, ok := y.(*Interface); ok {
+			a := x.allMethods
+			b := y.allMethods
+			if len(a) == len(b) {
+				// Interface types are the only types where cycles can occur
+				// that are not "terminated" via named types; and such cycles
+				// can only be created via method parameter types that are
+				// anonymous interfaces (directly or indirectly) embedding
+				// the current interface. Example:
+				//
+				//    type T interface {
+				//        m() interface{T}
+				//    }
+				//
+				// If two such (differently named) interfaces are compared,
+				// endless recursion occurs if the cycle is not detected.
+				//
+				// If x and y were compared before, they must be equal
+				// (if they were not, the recursion would have stopped);
+				// search the ifacePair stack for the same pair.
+				//
+				// This is a quadratic algorithm, but in practice these stacks
+				// are extremely short (bounded by the nesting depth of interface
+				// type declarations that recur via parameter types, an extremely
+				// rare occurrence). An alternative implementation might use a
+				// "visited" map, but that is probably less efficient overall.
+				q := &ifacePair{x, y, p}
+				for p != nil {
+					if p.identical(q) {
+						return true // same pair was compared before
+					}
+					p = p.prev
+				}
+				if debug {
+					assert(sort.IsSorted(byUniqueMethodName(a)))
+					assert(sort.IsSorted(byUniqueMethodName(b)))
+				}
+				for i, f := range a {
+					g := b[i]
+					if f.Id() != g.Id() || !identical(f.typ, g.typ, q) {
+						return false
+					}
+				}
+				return true
+			}
+		}
+
+	case *Map:
+		// Two map types are identical if they have identical key and value types.
+		if y, ok := y.(*Map); ok {
+			return identical(x.key, y.key, p) && identical(x.elem, y.elem, p)
+		}
+
+	case *Chan:
+		// Two channel types are identical if they have identical value types
+		// and the same direction.
+		if y, ok := y.(*Chan); ok {
+			return x.dir == y.dir && identical(x.elem, y.elem, p)
+		}
+
+	case *Named:
+		// Two named types are identical if their type names originate
+		// in the same type declaration.
+		if y, ok := y.(*Named); ok {
+			return x.obj == y.obj
+		}
+
+	default:
+		unreachable()
+	}
+
+	return false
+}
+
+// defaultType returns the default "typed" type for an "untyped" type;
+// it returns the incoming type for all other types. The default type
+// for untyped nil is untyped nil.
+//
+func defaultType(typ Type) Type {
+	if t, ok := typ.(*Basic); ok {
+		switch t.kind {
+		case UntypedBool:
+			return Typ[Bool]
+		case UntypedInt:
+			return Typ[Int]
+		case UntypedRune:
+			return universeRune // use 'rune' name
+		case UntypedFloat:
+			return Typ[Float64]
+		case UntypedComplex:
+			return Typ[Complex128]
+		case UntypedString:
+			return Typ[String]
+		}
+	}
+	return typ
+}
diff --git a/libgo/go/go/types/resolver.go b/libgo/go/go/types/resolver.go
new file mode 100644
index 00000000000..c31ef423d9a
--- /dev/null
+++ b/libgo/go/go/types/resolver.go
@@ -0,0 +1,445 @@
+// Copyright 2013 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 types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+	pathLib "path"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+// A declInfo describes a package-level const, type, var, or func declaration.
+type declInfo struct {
+	file  *Scope        // scope of file containing this declaration
+	lhs   []*Var        // lhs of n:1 variable declarations, or nil
+	typ   ast.Expr      // type, or nil
+	init  ast.Expr      // init expression, or nil
+	fdecl *ast.FuncDecl // func declaration, or nil
+
+	deps map[Object]bool // type and init dependencies; lazily allocated
+	mark int             // for dependency analysis
+}
+
+// hasInitializer reports whether the declared object has an initialization
+// expression or function body.
+func (d *declInfo) hasInitializer() bool {
+	return d.init != nil || d.fdecl != nil && d.fdecl.Body != nil
+}
+
+// addDep adds obj as a dependency to d.
+func (d *declInfo) addDep(obj Object) {
+	m := d.deps
+	if m == nil {
+		m = make(map[Object]bool)
+		d.deps = m
+	}
+	m[obj] = true
+}
+
+// arityMatch checks that the lhs and rhs of a const or var decl
+// have the appropriate number of names and init exprs. For const
+// decls, init is the value spec providing the init exprs; for
+// var decls, init is nil (the init exprs are in s in this case).
+func (check *Checker) arityMatch(s, init *ast.ValueSpec) {
+	l := len(s.Names)
+	r := len(s.Values)
+	if init != nil {
+		r = len(init.Values)
+	}
+
+	switch {
+	case init == nil && r == 0:
+		// var decl w/o init expr
+		if s.Type == nil {
+			check.errorf(s.Pos(), "missing type or init expr")
+		}
+	case l < r:
+		if l < len(s.Values) {
+			// init exprs from s
+			n := s.Values[l]
+			check.errorf(n.Pos(), "extra init expr %s", n)
+			// TODO(gri) avoid declared but not used error here
+		} else {
+			// init exprs "inherited"
+			check.errorf(s.Pos(), "extra init expr at %s", init.Pos())
+			// TODO(gri) avoid declared but not used error here
+		}
+	case l > r && (init != nil || r != 1):
+		n := s.Names[r]
+		check.errorf(n.Pos(), "missing init expr for %s", n)
+	}
+}
+
+func validatedImportPath(path string) (string, error) {
+	s, err := strconv.Unquote(path)
+	if err != nil {
+		return "", err
+	}
+	if s == "" {
+		return "", fmt.Errorf("empty string")
+	}
+	const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
+	for _, r := range s {
+		if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
+			return s, fmt.Errorf("invalid character %#U", r)
+		}
+	}
+	return s, nil
+}
+
+// declarePkgObj declares obj in the package scope, records its ident -> obj mapping,
+// and updates check.objMap. The object must not be a function or method.
+func (check *Checker) declarePkgObj(ident *ast.Ident, obj Object, d *declInfo) {
+	assert(ident.Name == obj.Name())
+
+	// spec: "A package-scope or file-scope identifier with name init
+	// may only be declared to be a function with this (func()) signature."
+	if ident.Name == "init" {
+		check.errorf(ident.Pos(), "cannot declare init - must be func")
+		return
+	}
+
+	check.declare(check.pkg.scope, ident, obj, token.NoPos)
+	check.objMap[obj] = d
+	obj.setOrder(uint32(len(check.objMap)))
+}
+
+// filename returns a filename suitable for debugging output.
+func (check *Checker) filename(fileNo int) string {
+	file := check.files[fileNo]
+	if pos := file.Pos(); pos.IsValid() {
+		return check.fset.File(pos).Name()
+	}
+	return fmt.Sprintf("file[%d]", fileNo)
+}
+
+// collectObjects collects all file and package objects and inserts them
+// into their respective scopes. It also performs imports and associates
+// methods with receiver base type names.
+func (check *Checker) collectObjects() {
+	pkg := check.pkg
+
+	// pkgImports is the set of packages already imported by any package file seen
+	// so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
+	// it (pkg.imports may not be empty if we are checking test files incrementally).
+	var pkgImports = make(map[*Package]bool)
+	for _, imp := range pkg.imports {
+		pkgImports[imp] = true
+	}
+
+	for fileNo, file := range check.files {
+		// The package identifier denotes the current package,
+		// but there is no corresponding package object.
+		check.recordDef(file.Name, nil)
+
+		// Use the actual source file extent rather than *ast.File extent since the
+		// latter doesn't include comments which appear at the start or end of the file.
+		// Be conservative and use the *ast.File extent if we don't have a *token.File.
+		pos, end := file.Pos(), file.End()
+		if f := check.fset.File(file.Pos()); f != nil {
+			pos, end = token.Pos(f.Base()), token.Pos(f.Base()+f.Size())
+		}
+		fileScope := NewScope(check.pkg.scope, pos, end, check.filename(fileNo))
+		check.recordScope(file, fileScope)
+
+		for _, decl := range file.Decls {
+			switch d := decl.(type) {
+			case *ast.BadDecl:
+				// ignore
+
+			case *ast.GenDecl:
+				var last *ast.ValueSpec // last ValueSpec with type or init exprs seen
+				for iota, spec := range d.Specs {
+					switch s := spec.(type) {
+					case *ast.ImportSpec:
+						// import package
+						var imp *Package
+						path, err := validatedImportPath(s.Path.Value)
+						if err != nil {
+							check.errorf(s.Path.Pos(), "invalid import path (%s)", err)
+							continue
+						}
+						if path == "C" && check.conf.FakeImportC {
+							// TODO(gri) shouldn't create a new one each time
+							imp = NewPackage("C", "C")
+							imp.fake = true
+						} else if path == "unsafe" {
+							// package "unsafe" is known to the language
+							imp = Unsafe
+						} else {
+							if importer := check.conf.Importer; importer != nil {
+								imp, err = importer.Import(path)
+								if imp == nil && err == nil {
+									err = fmt.Errorf("Config.Importer.Import(%s) returned nil but no error", path)
+								}
+							} else {
+								err = fmt.Errorf("Config.Importer not installed")
+							}
+							if err != nil {
+								check.errorf(s.Path.Pos(), "could not import %s (%s)", path, err)
+								continue
+							}
+						}
+
+						// add package to list of explicit imports
+						// (this functionality is provided as a convenience
+						// for clients; it is not needed for type-checking)
+						if !pkgImports[imp] {
+							pkgImports[imp] = true
+							if imp != Unsafe {
+								pkg.imports = append(pkg.imports, imp)
+							}
+						}
+
+						// local name overrides imported package name
+						name := imp.name
+						if s.Name != nil {
+							name = s.Name.Name
+							if name == "init" {
+								check.errorf(s.Name.Pos(), "cannot declare init - must be func")
+								continue
+							}
+						}
+
+						obj := NewPkgName(s.Pos(), pkg, name, imp)
+						if s.Name != nil {
+							// in a dot-import, the dot represents the package
+							check.recordDef(s.Name, obj)
+						} else {
+							check.recordImplicit(s, obj)
+						}
+
+						// add import to file scope
+						if name == "." {
+							// merge imported scope with file scope
+							for _, obj := range imp.scope.elems {
+								// A package scope may contain non-exported objects,
+								// do not import them!
+								if obj.Exported() {
+									// TODO(gri) When we import a package, we create
+									// a new local package object. We should do the
+									// same for each dot-imported object. That way
+									// they can have correct position information.
+									// (We must not modify their existing position
+									// information because the same package - found
+									// via Config.Packages - may be dot-imported in
+									// another package!)
+									check.declare(fileScope, nil, obj, token.NoPos)
+									check.recordImplicit(s, obj)
+								}
+							}
+							// add position to set of dot-import positions for this file
+							// (this is only needed for "imported but not used" errors)
+							check.addUnusedDotImport(fileScope, imp, s.Pos())
+						} else {
+							// declare imported package object in file scope
+							check.declare(fileScope, nil, obj, token.NoPos)
+						}
+
+					case *ast.ValueSpec:
+						switch d.Tok {
+						case token.CONST:
+							// determine which initialization expressions to use
+							switch {
+							case s.Type != nil || len(s.Values) > 0:
+								last = s
+							case last == nil:
+								last = new(ast.ValueSpec) // make sure last exists
+							}
+
+							// declare all constants
+							for i, name := range s.Names {
+								obj := NewConst(name.Pos(), pkg, name.Name, nil, constant.MakeInt64(int64(iota)))
+
+								var init ast.Expr
+								if i < len(last.Values) {
+									init = last.Values[i]
+								}
+
+								d := &declInfo{file: fileScope, typ: last.Type, init: init}
+								check.declarePkgObj(name, obj, d)
+							}
+
+							check.arityMatch(s, last)
+
+						case token.VAR:
+							lhs := make([]*Var, len(s.Names))
+							// If there's exactly one rhs initializer, use
+							// the same declInfo d1 for all lhs variables
+							// so that each lhs variable depends on the same
+							// rhs initializer (n:1 var declaration).
+							var d1 *declInfo
+							if len(s.Values) == 1 {
+								// The lhs elements are only set up after the for loop below,
+								// but that's ok because declareVar only collects the declInfo
+								// for a later phase.
+								d1 = &declInfo{file: fileScope, lhs: lhs, typ: s.Type, init: s.Values[0]}
+							}
+
+							// declare all variables
+							for i, name := range s.Names {
+								obj := NewVar(name.Pos(), pkg, name.Name, nil)
+								lhs[i] = obj
+
+								d := d1
+								if d == nil {
+									// individual assignments
+									var init ast.Expr
+									if i < len(s.Values) {
+										init = s.Values[i]
+									}
+									d = &declInfo{file: fileScope, typ: s.Type, init: init}
+								}
+
+								check.declarePkgObj(name, obj, d)
+							}
+
+							check.arityMatch(s, nil)
+
+						default:
+							check.invalidAST(s.Pos(), "invalid token %s", d.Tok)
+						}
+
+					case *ast.TypeSpec:
+						obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Name, nil)
+						check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, typ: s.Type})
+
+					default:
+						check.invalidAST(s.Pos(), "unknown ast.Spec node %T", s)
+					}
+				}
+
+			case *ast.FuncDecl:
+				name := d.Name.Name
+				obj := NewFunc(d.Name.Pos(), pkg, name, nil)
+				if d.Recv == nil {
+					// regular function
+					if name == "init" {
+						// don't declare init functions in the package scope - they are invisible
+						obj.parent = pkg.scope
+						check.recordDef(d.Name, obj)
+						// init functions must have a body
+						if d.Body == nil {
+							check.softErrorf(obj.pos, "missing function body")
+						}
+					} else {
+						check.declare(pkg.scope, d.Name, obj, token.NoPos)
+					}
+				} else {
+					// method
+					check.recordDef(d.Name, obj)
+					// Associate method with receiver base type name, if possible.
+					// Ignore methods that have an invalid receiver, or a blank _
+					// receiver name. They will be type-checked later, with regular
+					// functions.
+					if list := d.Recv.List; len(list) > 0 {
+						typ := list[0].Type
+						if ptr, _ := typ.(*ast.StarExpr); ptr != nil {
+							typ = ptr.X
+						}
+						if base, _ := typ.(*ast.Ident); base != nil && base.Name != "_" {
+							check.assocMethod(base.Name, obj)
+						}
+					}
+				}
+				info := &declInfo{file: fileScope, fdecl: d}
+				check.objMap[obj] = info
+				obj.setOrder(uint32(len(check.objMap)))
+
+			default:
+				check.invalidAST(d.Pos(), "unknown ast.Decl node %T", d)
+			}
+		}
+	}
+
+	// verify that objects in package and file scopes have different names
+	for _, scope := range check.pkg.scope.children /* file scopes */ {
+		for _, obj := range scope.elems {
+			if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
+				if pkg, ok := obj.(*PkgName); ok {
+					check.errorf(alt.Pos(), "%s already declared through import of %s", alt.Name(), pkg.Imported())
+					check.reportAltDecl(pkg)
+				} else {
+					check.errorf(alt.Pos(), "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
+					// TODO(gri) dot-imported objects don't have a position; reportAltDecl won't print anything
+					check.reportAltDecl(obj)
+				}
+			}
+		}
+	}
+}
+
+// packageObjects typechecks all package objects in objList, but not function bodies.
+func (check *Checker) packageObjects(objList []Object) {
+	// add new methods to already type-checked types (from a prior Checker.Files call)
+	for _, obj := range objList {
+		if obj, _ := obj.(*TypeName); obj != nil && obj.typ != nil {
+			check.addMethodDecls(obj)
+		}
+	}
+
+	// pre-allocate space for type declaration paths so that the underlying array is reused
+	typePath := make([]*TypeName, 0, 8)
+
+	for _, obj := range objList {
+		check.objDecl(obj, nil, typePath)
+	}
+
+	// At this point we may have a non-empty check.methods map; this means that not all
+	// entries were deleted at the end of typeDecl because the respective receiver base
+	// types were not found. In that case, an error was reported when declaring those
+	// methods. We can now safely discard this map.
+	check.methods = nil
+}
+
+// functionBodies typechecks all function bodies.
+func (check *Checker) functionBodies() {
+	for _, f := range check.funcs {
+		check.funcBody(f.decl, f.name, f.sig, f.body)
+	}
+}
+
+// unusedImports checks for unused imports.
+func (check *Checker) unusedImports() {
+	// if function bodies are not checked, packages' uses are likely missing - don't check
+	if check.conf.IgnoreFuncBodies {
+		return
+	}
+
+	// spec: "It is illegal (...) to directly import a package without referring to
+	// any of its exported identifiers. To import a package solely for its side-effects
+	// (initialization), use the blank identifier as explicit package name."
+
+	// check use of regular imported packages
+	for _, scope := range check.pkg.scope.children /* file scopes */ {
+		for _, obj := range scope.elems {
+			if obj, ok := obj.(*PkgName); ok {
+				// Unused "blank imports" are automatically ignored
+				// since _ identifiers are not entered into scopes.
+				if !obj.used {
+					path := obj.imported.path
+					base := pathLib.Base(path)
+					if obj.name == base {
+						check.softErrorf(obj.pos, "%q imported but not used", path)
+					} else {
+						check.softErrorf(obj.pos, "%q imported but not used as %s", path, obj.name)
+					}
+				}
+			}
+		}
+	}
+
+	// check use of dot-imported packages
+	for _, unusedDotImports := range check.unusedDotImports {
+		for pkg, pos := range unusedDotImports {
+			check.softErrorf(pos, "%q imported but not used", pkg.path)
+		}
+	}
+}
diff --git a/libgo/go/go/types/resolver_test.go b/libgo/go/go/types/resolver_test.go
new file mode 100644
index 00000000000..34deae268e3
--- /dev/null
+++ b/libgo/go/go/types/resolver_test.go
@@ -0,0 +1,209 @@
+// 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.
+
+package types_test
+
+import (
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"internal/testenv"
+	"sort"
+	"testing"
+
+	. "go/types"
+)
+
+type resolveTestImporter struct {
+	importer Importer
+	imported map[string]bool
+}
+
+func (imp *resolveTestImporter) Import(path string) (*Package, error) {
+	if imp.importer == nil {
+		imp.importer = importer.Default()
+		imp.imported = make(map[string]bool)
+	}
+	pkg, err := imp.importer.Import(path)
+	if err != nil {
+		return nil, err
+	}
+	imp.imported[path] = true
+	return pkg, nil
+}
+
+func TestResolveIdents(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	sources := []string{
+		`
+		package p
+		import "fmt"
+		import "math"
+		const pi = math.Pi
+		func sin(x float64) float64 {
+			return math.Sin(x)
+		}
+		var Println = fmt.Println
+		`,
+		`
+		package p
+		import "fmt"
+		type errorStringer struct { fmt.Stringer; error }
+		func f() string {
+			_ = "foo"
+			return fmt.Sprintf("%d", g())
+		}
+		func g() (x int) { return }
+		`,
+		`
+		package p
+		import . "go/parser"
+		import "sync"
+		func h() Mode { return ImportsOnly }
+		var _, x int = 1, 2
+		func init() {}
+		type T struct{ *sync.Mutex; a, b, c int}
+		type I interface{ m() }
+		var _ = T{a: 1, b: 2, c: 3}
+		func (_ T) m() {}
+		func (T) _() {}
+		var i I
+		var _ = i.m
+		func _(s []int) { for i, x := range s { _, _ = i, x } }
+		func _(x interface{}) {
+			switch x := x.(type) {
+			case int:
+				_ = x
+			}
+			switch {} // implicit 'true' tag
+		}
+		`,
+		`
+		package p
+		type S struct{}
+		func (T) _() {}
+		func (T) _() {}
+		`,
+		`
+		package p
+		func _() {
+		L0:
+		L1:
+			goto L0
+			for {
+				goto L1
+			}
+			if true {
+				goto L2
+			}
+		L2:
+		}
+		`,
+	}
+
+	pkgnames := []string{
+		"fmt",
+		"math",
+	}
+
+	// parse package files
+	fset := token.NewFileSet()
+	var files []*ast.File
+	for i, src := range sources {
+		f, err := parser.ParseFile(fset, fmt.Sprintf("sources[%d]", i), src, parser.DeclarationErrors)
+		if err != nil {
+			t.Fatal(err)
+		}
+		files = append(files, f)
+	}
+
+	// resolve and type-check package AST
+	importer := new(resolveTestImporter)
+	conf := Config{Importer: importer}
+	uses := make(map[*ast.Ident]Object)
+	defs := make(map[*ast.Ident]Object)
+	_, err := conf.Check("testResolveIdents", fset, files, &Info{Defs: defs, Uses: uses})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// check that all packages were imported
+	for _, name := range pkgnames {
+		if !importer.imported[name] {
+			t.Errorf("package %s not imported", name)
+		}
+	}
+
+	// check that qualified identifiers are resolved
+	for _, f := range files {
+		ast.Inspect(f, func(n ast.Node) bool {
+			if s, ok := n.(*ast.SelectorExpr); ok {
+				if x, ok := s.X.(*ast.Ident); ok {
+					obj := uses[x]
+					if obj == nil {
+						t.Errorf("%s: unresolved qualified identifier %s", fset.Position(x.Pos()), x.Name)
+						return false
+					}
+					if _, ok := obj.(*PkgName); ok && uses[s.Sel] == nil {
+						t.Errorf("%s: unresolved selector %s", fset.Position(s.Sel.Pos()), s.Sel.Name)
+						return false
+					}
+					return false
+				}
+				return false
+			}
+			return true
+		})
+	}
+
+	for id, obj := range uses {
+		if obj == nil {
+			t.Errorf("%s: Uses[%s] == nil", fset.Position(id.Pos()), id.Name)
+		}
+	}
+
+	// check that each identifier in the source is found in uses or defs or both
+	var both []string
+	for _, f := range files {
+		ast.Inspect(f, func(n ast.Node) bool {
+			if x, ok := n.(*ast.Ident); ok {
+				var objects int
+				if _, found := uses[x]; found {
+					objects |= 1
+					delete(uses, x)
+				}
+				if _, found := defs[x]; found {
+					objects |= 2
+					delete(defs, x)
+				}
+				if objects == 0 {
+					t.Errorf("%s: unresolved identifier %s", fset.Position(x.Pos()), x.Name)
+				} else if objects == 3 {
+					both = append(both, x.Name)
+				}
+				return false
+			}
+			return true
+		})
+	}
+
+	// check the expected set of idents that are simultaneously uses and defs
+	sort.Strings(both)
+	if got, want := fmt.Sprint(both), "[Mutex Stringer error]"; got != want {
+		t.Errorf("simultaneous uses/defs = %s, want %s", got, want)
+	}
+
+	// any left-over identifiers didn't exist in the source
+	for x := range uses {
+		t.Errorf("%s: identifier %s not present in source", fset.Position(x.Pos()), x.Name)
+	}
+	for x := range defs {
+		t.Errorf("%s: identifier %s not present in source", fset.Position(x.Pos()), x.Name)
+	}
+
+	// TODO(gri) add tests to check ImplicitObj callbacks
+}
diff --git a/libgo/go/go/types/return.go b/libgo/go/go/types/return.go
new file mode 100644
index 00000000000..66289852147
--- /dev/null
+++ b/libgo/go/go/types/return.go
@@ -0,0 +1,185 @@
+// Copyright 2013 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.
+
+// This file implements isTerminating.
+
+package types
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// isTerminating reports if s is a terminating statement.
+// If s is labeled, label is the label name; otherwise s
+// is "".
+func (check *Checker) isTerminating(s ast.Stmt, label string) bool {
+	switch s := s.(type) {
+	default:
+		unreachable()
+
+	case *ast.BadStmt, *ast.DeclStmt, *ast.EmptyStmt, *ast.SendStmt,
+		*ast.IncDecStmt, *ast.AssignStmt, *ast.GoStmt, *ast.DeferStmt,
+		*ast.RangeStmt:
+		// no chance
+
+	case *ast.LabeledStmt:
+		return check.isTerminating(s.Stmt, s.Label.Name)
+
+	case *ast.ExprStmt:
+		// the predeclared (possibly parenthesized) panic() function is terminating
+		if call, _ := unparen(s.X).(*ast.CallExpr); call != nil {
+			if id, _ := call.Fun.(*ast.Ident); id != nil {
+				if _, obj := check.scope.LookupParent(id.Name, token.NoPos); obj != nil {
+					if b, _ := obj.(*Builtin); b != nil && b.id == _Panic {
+						return true
+					}
+				}
+			}
+		}
+
+	case *ast.ReturnStmt:
+		return true
+
+	case *ast.BranchStmt:
+		if s.Tok == token.GOTO || s.Tok == token.FALLTHROUGH {
+			return true
+		}
+
+	case *ast.BlockStmt:
+		return check.isTerminatingList(s.List, "")
+
+	case *ast.IfStmt:
+		if s.Else != nil &&
+			check.isTerminating(s.Body, "") &&
+			check.isTerminating(s.Else, "") {
+			return true
+		}
+
+	case *ast.SwitchStmt:
+		return check.isTerminatingSwitch(s.Body, label)
+
+	case *ast.TypeSwitchStmt:
+		return check.isTerminatingSwitch(s.Body, label)
+
+	case *ast.SelectStmt:
+		for _, s := range s.Body.List {
+			cc := s.(*ast.CommClause)
+			if !check.isTerminatingList(cc.Body, "") || hasBreakList(cc.Body, label, true) {
+				return false
+			}
+
+		}
+		return true
+
+	case *ast.ForStmt:
+		if s.Cond == nil && !hasBreak(s.Body, label, true) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (check *Checker) isTerminatingList(list []ast.Stmt, label string) bool {
+	n := len(list)
+	return n > 0 && check.isTerminating(list[n-1], label)
+}
+
+func (check *Checker) isTerminatingSwitch(body *ast.BlockStmt, label string) bool {
+	hasDefault := false
+	for _, s := range body.List {
+		cc := s.(*ast.CaseClause)
+		if cc.List == nil {
+			hasDefault = true
+		}
+		if !check.isTerminatingList(cc.Body, "") || hasBreakList(cc.Body, label, true) {
+			return false
+		}
+	}
+	return hasDefault
+}
+
+// TODO(gri) For nested breakable statements, the current implementation of hasBreak
+//	     will traverse the same subtree repeatedly, once for each label. Replace
+//           with a single-pass label/break matching phase.
+
+// hasBreak reports if s is or contains a break statement
+// referring to the label-ed statement or implicit-ly the
+// closest outer breakable statement.
+func hasBreak(s ast.Stmt, label string, implicit bool) bool {
+	switch s := s.(type) {
+	default:
+		unreachable()
+
+	case *ast.BadStmt, *ast.DeclStmt, *ast.EmptyStmt, *ast.ExprStmt,
+		*ast.SendStmt, *ast.IncDecStmt, *ast.AssignStmt, *ast.GoStmt,
+		*ast.DeferStmt, *ast.ReturnStmt:
+		// no chance
+
+	case *ast.LabeledStmt:
+		return hasBreak(s.Stmt, label, implicit)
+
+	case *ast.BranchStmt:
+		if s.Tok == token.BREAK {
+			if s.Label == nil {
+				return implicit
+			}
+			if s.Label.Name == label {
+				return true
+			}
+		}
+
+	case *ast.BlockStmt:
+		return hasBreakList(s.List, label, implicit)
+
+	case *ast.IfStmt:
+		if hasBreak(s.Body, label, implicit) ||
+			s.Else != nil && hasBreak(s.Else, label, implicit) {
+			return true
+		}
+
+	case *ast.CaseClause:
+		return hasBreakList(s.Body, label, implicit)
+
+	case *ast.SwitchStmt:
+		if label != "" && hasBreak(s.Body, label, false) {
+			return true
+		}
+
+	case *ast.TypeSwitchStmt:
+		if label != "" && hasBreak(s.Body, label, false) {
+			return true
+		}
+
+	case *ast.CommClause:
+		return hasBreakList(s.Body, label, implicit)
+
+	case *ast.SelectStmt:
+		if label != "" && hasBreak(s.Body, label, false) {
+			return true
+		}
+
+	case *ast.ForStmt:
+		if label != "" && hasBreak(s.Body, label, false) {
+			return true
+		}
+
+	case *ast.RangeStmt:
+		if label != "" && hasBreak(s.Body, label, false) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func hasBreakList(list []ast.Stmt, label string, implicit bool) bool {
+	for _, s := range list {
+		if hasBreak(s, label, implicit) {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/go/types/scope.go b/libgo/go/go/types/scope.go
new file mode 100644
index 00000000000..3502840225f
--- /dev/null
+++ b/libgo/go/go/types/scope.go
@@ -0,0 +1,190 @@
+// Copyright 2013 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.
+
+// This file implements Scopes.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"io"
+	"sort"
+	"strings"
+)
+
+// TODO(gri) Provide scopes with a name or other mechanism so that
+//           objects can use that information for better printing.
+
+// A Scope maintains a set of objects and links to its containing
+// (parent) and contained (children) scopes. Objects may be inserted
+// and looked up by name. The zero value for Scope is a ready-to-use
+// empty scope.
+type Scope struct {
+	parent   *Scope
+	children []*Scope
+	elems    map[string]Object // lazily allocated
+	pos, end token.Pos         // scope extent; may be invalid
+	comment  string            // for debugging only
+}
+
+// NewScope returns a new, empty scope contained in the given parent
+// scope, if any.  The comment is for debugging only.
+func NewScope(parent *Scope, pos, end token.Pos, comment string) *Scope {
+	s := &Scope{parent, nil, nil, pos, end, comment}
+	// don't add children to Universe scope!
+	if parent != nil && parent != Universe {
+		parent.children = append(parent.children, s)
+	}
+	return s
+}
+
+// Parent returns the scope's containing (parent) scope.
+func (s *Scope) Parent() *Scope { return s.parent }
+
+// Len() returns the number of scope elements.
+func (s *Scope) Len() int { return len(s.elems) }
+
+// Names returns the scope's element names in sorted order.
+func (s *Scope) Names() []string {
+	names := make([]string, len(s.elems))
+	i := 0
+	for name := range s.elems {
+		names[i] = name
+		i++
+	}
+	sort.Strings(names)
+	return names
+}
+
+// NumChildren() returns the number of scopes nested in s.
+func (s *Scope) NumChildren() int { return len(s.children) }
+
+// Child returns the i'th child scope for 0 <= i < NumChildren().
+func (s *Scope) Child(i int) *Scope { return s.children[i] }
+
+// Lookup returns the object in scope s with the given name if such an
+// object exists; otherwise the result is nil.
+func (s *Scope) Lookup(name string) Object {
+	return s.elems[name]
+}
+
+// LookupParent follows the parent chain of scopes starting with s until
+// it finds a scope where Lookup(name) returns a non-nil object, and then
+// returns that scope and object. If a valid position pos is provided,
+// only objects that were declared at or before pos are considered.
+// If no such scope and object exists, the result is (nil, nil).
+//
+// Note that obj.Parent() may be different from the returned scope if the
+// object was inserted into the scope and already had a parent at that
+// time (see Insert, below). This can only happen for dot-imported objects
+// whose scope is the scope of the package that exported them.
+func (s *Scope) LookupParent(name string, pos token.Pos) (*Scope, Object) {
+	for ; s != nil; s = s.parent {
+		if obj := s.elems[name]; obj != nil && (!pos.IsValid() || obj.scopePos() <= pos) {
+			return s, obj
+		}
+	}
+	return nil, nil
+}
+
+// Insert attempts to insert an object obj into scope s.
+// If s already contains an alternative object alt with
+// the same name, Insert leaves s unchanged and returns alt.
+// Otherwise it inserts obj, sets the object's parent scope
+// if not already set, and returns nil.
+func (s *Scope) Insert(obj Object) Object {
+	name := obj.Name()
+	if alt := s.elems[name]; alt != nil {
+		return alt
+	}
+	if s.elems == nil {
+		s.elems = make(map[string]Object)
+	}
+	s.elems[name] = obj
+	if obj.Parent() == nil {
+		obj.setParent(s)
+	}
+	return nil
+}
+
+// Pos and End describe the scope's source code extent [pos, end).
+// The results are guaranteed to be valid only if the type-checked
+// AST has complete position information. The extent is undefined
+// for Universe and package scopes.
+func (s *Scope) Pos() token.Pos { return s.pos }
+func (s *Scope) End() token.Pos { return s.end }
+
+// Contains returns true if pos is within the scope's extent.
+// The result is guaranteed to be valid only if the type-checked
+// AST has complete position information.
+func (s *Scope) Contains(pos token.Pos) bool {
+	return s.pos <= pos && pos < s.end
+}
+
+// Innermost returns the innermost (child) scope containing
+// pos. If pos is not within any scope, the result is nil.
+// The result is also nil for the Universe scope.
+// The result is guaranteed to be valid only if the type-checked
+// AST has complete position information.
+func (s *Scope) Innermost(pos token.Pos) *Scope {
+	// Package scopes do not have extents since they may be
+	// discontiguous, so iterate over the package's files.
+	if s.parent == Universe {
+		for _, s := range s.children {
+			if inner := s.Innermost(pos); inner != nil {
+				return inner
+			}
+		}
+	}
+
+	if s.Contains(pos) {
+		for _, s := range s.children {
+			if s.Contains(pos) {
+				return s.Innermost(pos)
+			}
+		}
+		return s
+	}
+	return nil
+}
+
+// WriteTo writes a string representation of the scope to w,
+// with the scope elements sorted by name.
+// The level of indentation is controlled by n >= 0, with
+// n == 0 for no indentation.
+// If recurse is set, it also writes nested (children) scopes.
+func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) {
+	const ind = ".  "
+	indn := strings.Repeat(ind, n)
+
+	fmt.Fprintf(w, "%s%s scope %p {", indn, s.comment, s)
+	if len(s.elems) == 0 {
+		fmt.Fprintf(w, "}\n")
+		return
+	}
+
+	fmt.Fprintln(w)
+	indn1 := indn + ind
+	for _, name := range s.Names() {
+		fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name])
+	}
+
+	if recurse {
+		for _, s := range s.children {
+			fmt.Fprintln(w)
+			s.WriteTo(w, n+1, recurse)
+		}
+	}
+
+	fmt.Fprintf(w, "%s}", indn)
+}
+
+// String returns a string representation of the scope, for debugging.
+func (s *Scope) String() string {
+	var buf bytes.Buffer
+	s.WriteTo(&buf, 0, false)
+	return buf.String()
+}
diff --git a/libgo/go/go/types/selection.go b/libgo/go/go/types/selection.go
new file mode 100644
index 00000000000..124e0d39f02
--- /dev/null
+++ b/libgo/go/go/types/selection.go
@@ -0,0 +1,143 @@
+// Copyright 2013 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.
+
+// This file implements Selections.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// SelectionKind describes the kind of a selector expression x.f
+// (excluding qualified identifiers).
+type SelectionKind int
+
+const (
+	FieldVal   SelectionKind = iota // x.f is a struct field selector
+	MethodVal                       // x.f is a method selector
+	MethodExpr                      // x.f is a method expression
+)
+
+// A Selection describes a selector expression x.f.
+// For the declarations:
+//
+//	type T struct{ x int; E }
+//	type E struct{}
+//	func (e E) m() {}
+//	var p *T
+//
+// the following relations exist:
+//
+//	Selector    Kind          Recv    Obj    Type               Index     Indirect
+//
+//	p.x         FieldVal      T       x      int                {0}       true
+//	p.m         MethodVal     *T      m      func (e *T) m()    {1, 0}    true
+//	T.m         MethodExpr    T       m      func m(_ T)        {1, 0}    false
+//
+type Selection struct {
+	kind     SelectionKind
+	recv     Type   // type of x
+	obj      Object // object denoted by x.f
+	index    []int  // path from x to x.f
+	indirect bool   // set if there was any pointer indirection on the path
+}
+
+// Kind returns the selection kind.
+func (s *Selection) Kind() SelectionKind { return s.kind }
+
+// Recv returns the type of x in x.f.
+func (s *Selection) Recv() Type { return s.recv }
+
+// Obj returns the object denoted by x.f; a *Var for
+// a field selection, and a *Func in all other cases.
+func (s *Selection) Obj() Object { return s.obj }
+
+// Type returns the type of x.f, which may be different from the type of f.
+// See Selection for more information.
+func (s *Selection) Type() Type {
+	switch s.kind {
+	case MethodVal:
+		// The type of x.f is a method with its receiver type set
+		// to the type of x.
+		sig := *s.obj.(*Func).typ.(*Signature)
+		recv := *sig.recv
+		recv.typ = s.recv
+		sig.recv = &recv
+		return &sig
+
+	case MethodExpr:
+		// The type of x.f is a function (without receiver)
+		// and an additional first argument with the same type as x.
+		// TODO(gri) Similar code is already in call.go - factor!
+		// TODO(gri) Compute this eagerly to avoid allocations.
+		sig := *s.obj.(*Func).typ.(*Signature)
+		arg0 := *sig.recv
+		sig.recv = nil
+		arg0.typ = s.recv
+		var params []*Var
+		if sig.params != nil {
+			params = sig.params.vars
+		}
+		sig.params = NewTuple(append([]*Var{&arg0}, params...)...)
+		return &sig
+	}
+
+	// In all other cases, the type of x.f is the type of x.
+	return s.obj.Type()
+}
+
+// Index describes the path from x to f in x.f.
+// The last index entry is the field or method index of the type declaring f;
+// either:
+//
+//	1) the list of declared methods of a named type; or
+//	2) the list of methods of an interface type; or
+//	3) the list of fields of a struct type.
+//
+// The earlier index entries are the indices of the embedded fields implicitly
+// traversed to get from (the type of) x to f, starting at embedding depth 0.
+func (s *Selection) Index() []int { return s.index }
+
+// Indirect reports whether any pointer indirection was required to get from
+// x to f in x.f.
+func (s *Selection) Indirect() bool { return s.indirect }
+
+func (s *Selection) String() string { return SelectionString(s, nil) }
+
+// SelectionString returns the string form of s.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+//
+// Examples:
+//	"field (T) f int"
+//	"method (T) f(X) Y"
+//	"method expr (T) f(X) Y"
+//
+func SelectionString(s *Selection, qf Qualifier) string {
+	var k string
+	switch s.kind {
+	case FieldVal:
+		k = "field "
+	case MethodVal:
+		k = "method "
+	case MethodExpr:
+		k = "method expr "
+	default:
+		unreachable()
+	}
+	var buf bytes.Buffer
+	buf.WriteString(k)
+	buf.WriteByte('(')
+	WriteType(&buf, s.Recv(), qf)
+	fmt.Fprintf(&buf, ") %s", s.obj.Name())
+	if T := s.Type(); s.kind == FieldVal {
+		buf.WriteByte(' ')
+		WriteType(&buf, T, qf)
+	} else {
+		WriteSignature(&buf, T.(*Signature), qf)
+	}
+	return buf.String()
+}
diff --git a/libgo/go/go/types/self_test.go b/libgo/go/go/types/self_test.go
new file mode 100644
index 00000000000..10ad06fbca1
--- /dev/null
+++ b/libgo/go/go/types/self_test.go
@@ -0,0 +1,102 @@
+// Copyright 2013 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 types_test
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"path/filepath"
+	"testing"
+	"time"
+
+	. "go/types"
+)
+
+var benchmark = flag.Bool("b", false, "run benchmarks")
+
+func TestSelf(t *testing.T) {
+	fset := token.NewFileSet()
+	files, err := pkgFiles(fset, ".")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	conf := Config{Importer: importer.Default()}
+	_, err = conf.Check("go/types", fset, files, nil)
+	if err != nil {
+		// Importing go/constant doesn't work in the
+		// build dashboard environment. Don't report an error
+		// for now so that the build remains green.
+		// TODO(gri) fix this
+		t.Log(err) // replace w/ t.Fatal eventually
+		return
+	}
+}
+
+func TestBenchmark(t *testing.T) {
+	if !*benchmark {
+		return
+	}
+
+	// We're not using testing's benchmarking mechanism directly
+	// because we want custom output.
+
+	for _, p := range []string{"types", "constant", filepath.Join("internal", "gcimporter")} {
+		path := filepath.Join("..", p)
+		runbench(t, path, false)
+		runbench(t, path, true)
+		fmt.Println()
+	}
+}
+
+func runbench(t *testing.T, path string, ignoreFuncBodies bool) {
+	fset := token.NewFileSet()
+	files, err := pkgFiles(fset, path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	b := testing.Benchmark(func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			conf := Config{IgnoreFuncBodies: ignoreFuncBodies}
+			conf.Check(path, fset, files, nil)
+		}
+	})
+
+	// determine line count
+	lines := 0
+	fset.Iterate(func(f *token.File) bool {
+		lines += f.LineCount()
+		return true
+	})
+
+	d := time.Duration(b.NsPerOp())
+	fmt.Printf(
+		"%s: %s for %d lines (%d lines/s), ignoreFuncBodies = %v\n",
+		filepath.Base(path), d, lines, int64(float64(lines)/d.Seconds()), ignoreFuncBodies,
+	)
+}
+
+func pkgFiles(fset *token.FileSet, path string) ([]*ast.File, error) {
+	filenames, err := pkgFilenames(path) // from stdlib_test.go
+	if err != nil {
+		return nil, err
+	}
+
+	var files []*ast.File
+	for _, filename := range filenames {
+		file, err := parser.ParseFile(fset, filename, nil, 0)
+		if err != nil {
+			return nil, err
+		}
+		files = append(files, file)
+	}
+
+	return files, nil
+}
diff --git a/libgo/go/go/types/sizes.go b/libgo/go/go/types/sizes.go
new file mode 100644
index 00000000000..56fb310c294
--- /dev/null
+++ b/libgo/go/go/types/sizes.go
@@ -0,0 +1,211 @@
+// Copyright 2013 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.
+
+// This file implements Sizes.
+
+package types
+
+// Sizes defines the sizing functions for package unsafe.
+type Sizes interface {
+	// Alignof returns the alignment of a variable of type T.
+	// Alignof must implement the alignment guarantees required by the spec.
+	Alignof(T Type) int64
+
+	// Offsetsof returns the offsets of the given struct fields, in bytes.
+	// Offsetsof must implement the offset guarantees required by the spec.
+	Offsetsof(fields []*Var) []int64
+
+	// Sizeof returns the size of a variable of type T.
+	// Sizeof must implement the size guarantees required by the spec.
+	Sizeof(T Type) int64
+}
+
+// StdSizes is a convenience type for creating commonly used Sizes.
+// It makes the following simplifying assumptions:
+//
+//	- The size of explicitly sized basic types (int16, etc.) is the
+//	  specified size.
+//	- The size of strings and interfaces is 2*WordSize.
+//	- The size of slices is 3*WordSize.
+//	- The size of an array of n elements corresponds to the size of
+//	  a struct of n consecutive fields of the array's element type.
+//      - The size of a struct is the offset of the last field plus that
+//	  field's size. As with all element types, if the struct is used
+//	  in an array its size must first be aligned to a multiple of the
+//	  struct's alignment.
+//	- All other types have size WordSize.
+//	- Arrays and structs are aligned per spec definition; all other
+//	  types are naturally aligned with a maximum alignment MaxAlign.
+//
+// *StdSizes implements Sizes.
+//
+type StdSizes struct {
+	WordSize int64 // word size in bytes - must be >= 4 (32bits)
+	MaxAlign int64 // maximum alignment in bytes - must be >= 1
+}
+
+func (s *StdSizes) Alignof(T Type) int64 {
+	// For arrays and structs, alignment is defined in terms
+	// of alignment of the elements and fields, respectively.
+	switch t := T.Underlying().(type) {
+	case *Array:
+		// spec: "For a variable x of array type: unsafe.Alignof(x)
+		// is the same as unsafe.Alignof(x[0]), but at least 1."
+		return s.Alignof(t.elem)
+	case *Struct:
+		// spec: "For a variable x of struct type: unsafe.Alignof(x)
+		// is the largest of the values unsafe.Alignof(x.f) for each
+		// field f of x, but at least 1."
+		max := int64(1)
+		for _, f := range t.fields {
+			if a := s.Alignof(f.typ); a > max {
+				max = a
+			}
+		}
+		return max
+	}
+	a := s.Sizeof(T) // may be 0
+	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
+	if a < 1 {
+		return 1
+	}
+	if a > s.MaxAlign {
+		return s.MaxAlign
+	}
+	return a
+}
+
+func (s *StdSizes) Offsetsof(fields []*Var) []int64 {
+	offsets := make([]int64, len(fields))
+	var o int64
+	for i, f := range fields {
+		a := s.Alignof(f.typ)
+		o = align(o, a)
+		offsets[i] = o
+		o += s.Sizeof(f.typ)
+	}
+	return offsets
+}
+
+var basicSizes = [...]byte{
+	Bool:       1,
+	Int8:       1,
+	Int16:      2,
+	Int32:      4,
+	Int64:      8,
+	Uint8:      1,
+	Uint16:     2,
+	Uint32:     4,
+	Uint64:     8,
+	Float32:    4,
+	Float64:    8,
+	Complex64:  8,
+	Complex128: 16,
+}
+
+func (s *StdSizes) Sizeof(T Type) int64 {
+	switch t := T.Underlying().(type) {
+	case *Basic:
+		assert(isTyped(T))
+		k := t.kind
+		if int(k) < len(basicSizes) {
+			if s := basicSizes[k]; s > 0 {
+				return int64(s)
+			}
+		}
+		if k == String {
+			return s.WordSize * 2
+		}
+	case *Array:
+		n := t.len
+		if n == 0 {
+			return 0
+		}
+		a := s.Alignof(t.elem)
+		z := s.Sizeof(t.elem)
+		return align(z, a)*(n-1) + z
+	case *Slice:
+		return s.WordSize * 3
+	case *Struct:
+		n := t.NumFields()
+		if n == 0 {
+			return 0
+		}
+		offsets := t.offsets
+		if t.offsets == nil {
+			// compute offsets on demand
+			offsets = s.Offsetsof(t.fields)
+			t.offsets = offsets
+		}
+		return offsets[n-1] + s.Sizeof(t.fields[n-1].typ)
+	case *Interface:
+		return s.WordSize * 2
+	}
+	return s.WordSize // catch-all
+}
+
+// stdSizes is used if Config.Sizes == nil.
+var stdSizes = StdSizes{8, 8}
+
+func (conf *Config) alignof(T Type) int64 {
+	if s := conf.Sizes; s != nil {
+		if a := s.Alignof(T); a >= 1 {
+			return a
+		}
+		panic("Config.Sizes.Alignof returned an alignment < 1")
+	}
+	return stdSizes.Alignof(T)
+}
+
+func (conf *Config) offsetsof(T *Struct) []int64 {
+	offsets := T.offsets
+	if offsets == nil && T.NumFields() > 0 {
+		// compute offsets on demand
+		if s := conf.Sizes; s != nil {
+			offsets = s.Offsetsof(T.fields)
+			// sanity checks
+			if len(offsets) != T.NumFields() {
+				panic("Config.Sizes.Offsetsof returned the wrong number of offsets")
+			}
+			for _, o := range offsets {
+				if o < 0 {
+					panic("Config.Sizes.Offsetsof returned an offset < 0")
+				}
+			}
+		} else {
+			offsets = stdSizes.Offsetsof(T.fields)
+		}
+		T.offsets = offsets
+	}
+	return offsets
+}
+
+// offsetof returns the offset of the field specified via
+// the index sequence relative to typ. All embedded fields
+// must be structs (rather than pointer to structs).
+func (conf *Config) offsetof(typ Type, index []int) int64 {
+	var o int64
+	for _, i := range index {
+		s := typ.Underlying().(*Struct)
+		o += conf.offsetsof(s)[i]
+		typ = s.fields[i].typ
+	}
+	return o
+}
+
+func (conf *Config) sizeof(T Type) int64 {
+	if s := conf.Sizes; s != nil {
+		if z := s.Sizeof(T); z >= 0 {
+			return z
+		}
+		panic("Config.Sizes.Sizeof returned a size < 0")
+	}
+	return stdSizes.Sizeof(T)
+}
+
+// align returns the smallest y >= x such that y % a == 0.
+func align(x, a int64) int64 {
+	y := x + a - 1
+	return y - y%a
+}
diff --git a/libgo/go/go/types/stdlib_test.go b/libgo/go/go/types/stdlib_test.go
new file mode 100644
index 00000000000..c6c946e976a
--- /dev/null
+++ b/libgo/go/go/types/stdlib_test.go
@@ -0,0 +1,279 @@
+// Copyright 2013 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.
+
+// This file tests types.Check by using it to
+// typecheck the standard library and tests.
+
+package types_test
+
+import (
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/importer"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	. "go/types"
+)
+
+var (
+	pkgCount int // number of packages processed
+	start    time.Time
+
+	// Use the same importer for all std lib tests to
+	// avoid repeated importing of the same packages.
+	stdLibImporter = importer.Default()
+)
+
+func TestStdlib(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	start = time.Now()
+	walkDirs(t, filepath.Join(runtime.GOROOT(), "src"))
+	if testing.Verbose() {
+		fmt.Println(pkgCount, "packages typechecked in", time.Since(start))
+	}
+}
+
+// firstComment returns the contents of the first comment in
+// the given file, assuming there's one within the first KB.
+func firstComment(filename string) string {
+	f, err := os.Open(filename)
+	if err != nil {
+		return ""
+	}
+	defer f.Close()
+
+	var src [1 << 10]byte // read at most 1KB
+	n, _ := f.Read(src[:])
+
+	var s scanner.Scanner
+	s.Init(fset.AddFile("", fset.Base(), n), src[:n], nil, scanner.ScanComments)
+	for {
+		_, tok, lit := s.Scan()
+		switch tok {
+		case token.COMMENT:
+			// remove trailing */ of multi-line comment
+			if lit[1] == '*' {
+				lit = lit[:len(lit)-2]
+			}
+			return strings.TrimSpace(lit[2:])
+		case token.EOF:
+			return ""
+		}
+	}
+}
+
+func testTestDir(t *testing.T, path string, ignore ...string) {
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	excluded := make(map[string]bool)
+	for _, filename := range ignore {
+		excluded[filename] = true
+	}
+
+	fset := token.NewFileSet()
+	for _, f := range files {
+		// filter directory contents
+		if f.IsDir() || !strings.HasSuffix(f.Name(), ".go") || excluded[f.Name()] {
+			continue
+		}
+
+		// get per-file instructions
+		expectErrors := false
+		filename := filepath.Join(path, f.Name())
+		if cmd := firstComment(filename); cmd != "" {
+			switch cmd {
+			case "skip", "compiledir":
+				continue // ignore this file
+			case "errorcheck":
+				expectErrors = true
+			}
+		}
+
+		// parse and type-check file
+		file, err := parser.ParseFile(fset, filename, nil, 0)
+		if err == nil {
+			conf := Config{Importer: stdLibImporter}
+			_, err = conf.Check(filename, fset, []*ast.File{file}, nil)
+		}
+
+		if expectErrors {
+			if err == nil {
+				t.Errorf("expected errors but found none in %s", filename)
+			}
+		} else {
+			if err != nil {
+				t.Error(err)
+			}
+		}
+	}
+}
+
+func TestStdTest(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	// test/recover4.go is only built for Linux and Darwin.
+	// TODO(gri) Remove once tests consider +build tags (issue 10370).
+	if runtime.GOOS != "linux" && runtime.GOOS != "darwin" {
+		return
+	}
+
+	testTestDir(t, filepath.Join(runtime.GOROOT(), "test"),
+		"cmplxdivide.go", // also needs file cmplxdivide1.go - ignore
+		"sigchld.go",     // don't work on Windows; testTestDir should consult build tags
+	)
+}
+
+func TestStdFixed(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	testTestDir(t, filepath.Join(runtime.GOROOT(), "test", "fixedbugs"),
+		"bug248.go", "bug302.go", "bug369.go", // complex test instructions - ignore
+		"bug459.go",      // possibly incorrect test - see issue 6703 (pending spec clarification)
+		"issue3924.go",   // possibly incorrect test - see issue 6671 (pending spec clarification)
+		"issue6889.go",   // gc-specific test
+		"issue7746.go",   // large constants - consumes too much memory
+		"issue11326.go",  // large constants
+		"issue11326b.go", // large constants
+	)
+}
+
+func TestStdKen(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	testTestDir(t, filepath.Join(runtime.GOROOT(), "test", "ken"))
+}
+
+// Package paths of excluded packages.
+var excluded = map[string]bool{
+	"builtin": true,
+}
+
+// typecheck typechecks the given package files.
+func typecheck(t *testing.T, path string, filenames []string) {
+	fset := token.NewFileSet()
+
+	// parse package files
+	var files []*ast.File
+	for _, filename := range filenames {
+		file, err := parser.ParseFile(fset, filename, nil, parser.AllErrors)
+		if err != nil {
+			// the parser error may be a list of individual errors; report them all
+			if list, ok := err.(scanner.ErrorList); ok {
+				for _, err := range list {
+					t.Error(err)
+				}
+				return
+			}
+			t.Error(err)
+			return
+		}
+
+		if testing.Verbose() {
+			if len(files) == 0 {
+				fmt.Println("package", file.Name.Name)
+			}
+			fmt.Println("\t", filename)
+		}
+
+		files = append(files, file)
+	}
+
+	// typecheck package files
+	conf := Config{
+		Error:    func(err error) { t.Error(err) },
+		Importer: stdLibImporter,
+	}
+	info := Info{Uses: make(map[*ast.Ident]Object)}
+	conf.Check(path, fset, files, &info)
+	pkgCount++
+
+	// Perform checks of API invariants.
+
+	// All Objects have a package, except predeclared ones.
+	errorError := Universe.Lookup("error").Type().Underlying().(*Interface).ExplicitMethod(0) // (error).Error
+	for id, obj := range info.Uses {
+		predeclared := obj == Universe.Lookup(obj.Name()) || obj == errorError
+		if predeclared == (obj.Pkg() != nil) {
+			posn := fset.Position(id.Pos())
+			if predeclared {
+				t.Errorf("%s: predeclared object with package: %s", posn, obj)
+			} else {
+				t.Errorf("%s: user-defined object without package: %s", posn, obj)
+			}
+		}
+	}
+}
+
+// pkgFilenames returns the list of package filenames for the given directory.
+func pkgFilenames(dir string) ([]string, error) {
+	ctxt := build.Default
+	ctxt.CgoEnabled = false
+	pkg, err := ctxt.ImportDir(dir, 0)
+	if err != nil {
+		if _, nogo := err.(*build.NoGoError); nogo {
+			return nil, nil // no *.go files, not an error
+		}
+		return nil, err
+	}
+	if excluded[pkg.ImportPath] {
+		return nil, nil
+	}
+	var filenames []string
+	for _, name := range pkg.GoFiles {
+		filenames = append(filenames, filepath.Join(pkg.Dir, name))
+	}
+	for _, name := range pkg.TestGoFiles {
+		filenames = append(filenames, filepath.Join(pkg.Dir, name))
+	}
+	return filenames, nil
+}
+
+// Note: Could use filepath.Walk instead of walkDirs but that wouldn't
+//       necessarily be shorter or clearer after adding the code to
+//       terminate early for -short tests.
+
+func walkDirs(t *testing.T, dir string) {
+	// limit run time for short tests
+	if testing.Short() && time.Since(start) >= 750*time.Millisecond {
+		return
+	}
+
+	fis, err := ioutil.ReadDir(dir)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	// typecheck package in directory
+	files, err := pkgFilenames(dir)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if files != nil {
+		typecheck(t, dir, files)
+	}
+
+	// traverse subdirectories, but don't walk into testdata
+	for _, fi := range fis {
+		if fi.IsDir() && fi.Name() != "testdata" {
+			walkDirs(t, filepath.Join(dir, fi.Name()))
+		}
+	}
+}
diff --git a/libgo/go/go/types/stmt.go b/libgo/go/go/types/stmt.go
new file mode 100644
index 00000000000..88a1d9b8668
--- /dev/null
+++ b/libgo/go/go/types/stmt.go
@@ -0,0 +1,744 @@
+// 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.
+
+// This file implements typechecking of statements.
+
+package types
+
+import (
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/token"
+)
+
+func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body *ast.BlockStmt) {
+	if trace {
+		if name == "" {
+			name = "<function literal>"
+		}
+		fmt.Printf("--- %s: %s {\n", name, sig)
+		defer fmt.Println("--- <end>")
+	}
+
+	// set function scope extent
+	sig.scope.pos = body.Pos()
+	sig.scope.end = body.End()
+
+	// save/restore current context and setup function context
+	// (and use 0 indentation at function start)
+	defer func(ctxt context, indent int) {
+		check.context = ctxt
+		check.indent = indent
+	}(check.context, check.indent)
+	check.context = context{
+		decl:  decl,
+		scope: sig.scope,
+		sig:   sig,
+	}
+	check.indent = 0
+
+	check.stmtList(0, body.List)
+
+	if check.hasLabel {
+		check.labels(body)
+	}
+
+	if sig.results.Len() > 0 && !check.isTerminating(body, "") {
+		check.error(body.Rbrace, "missing return")
+	}
+
+	// spec: "Implementation restriction: A compiler may make it illegal to
+	// declare a variable inside a function body if the variable is never used."
+	// (One could check each scope after use, but that distributes this check
+	// over several places because CloseScope is not always called explicitly.)
+	check.usage(sig.scope)
+}
+
+func (check *Checker) usage(scope *Scope) {
+	for _, obj := range scope.elems {
+		if v, _ := obj.(*Var); v != nil && !v.used {
+			check.softErrorf(v.pos, "%s declared but not used", v.name)
+		}
+	}
+	for _, scope := range scope.children {
+		check.usage(scope)
+	}
+}
+
+// stmtContext is a bitset describing which
+// control-flow statements are permissible.
+type stmtContext uint
+
+const (
+	breakOk stmtContext = 1 << iota
+	continueOk
+	fallthroughOk
+)
+
+func (check *Checker) simpleStmt(s ast.Stmt) {
+	if s != nil {
+		check.stmt(0, s)
+	}
+}
+
+func (check *Checker) stmtList(ctxt stmtContext, list []ast.Stmt) {
+	ok := ctxt&fallthroughOk != 0
+	inner := ctxt &^ fallthroughOk
+	for i, s := range list {
+		inner := inner
+		if ok && i+1 == len(list) {
+			inner |= fallthroughOk
+		}
+		check.stmt(inner, s)
+	}
+}
+
+func (check *Checker) multipleDefaults(list []ast.Stmt) {
+	var first ast.Stmt
+	for _, s := range list {
+		var d ast.Stmt
+		switch c := s.(type) {
+		case *ast.CaseClause:
+			if len(c.List) == 0 {
+				d = s
+			}
+		case *ast.CommClause:
+			if c.Comm == nil {
+				d = s
+			}
+		default:
+			check.invalidAST(s.Pos(), "case/communication clause expected")
+		}
+		if d != nil {
+			if first != nil {
+				check.errorf(d.Pos(), "multiple defaults (first at %s)", first.Pos())
+			} else {
+				first = d
+			}
+		}
+	}
+}
+
+func (check *Checker) openScope(s ast.Stmt, comment string) {
+	scope := NewScope(check.scope, s.Pos(), s.End(), comment)
+	check.recordScope(s, scope)
+	check.scope = scope
+}
+
+func (check *Checker) closeScope() {
+	check.scope = check.scope.Parent()
+}
+
+func assignOp(op token.Token) token.Token {
+	// token_test.go verifies the token ordering this function relies on
+	if token.ADD_ASSIGN <= op && op <= token.AND_NOT_ASSIGN {
+		return op + (token.ADD - token.ADD_ASSIGN)
+	}
+	return token.ILLEGAL
+}
+
+func (check *Checker) suspendedCall(keyword string, call *ast.CallExpr) {
+	var x operand
+	var msg string
+	switch check.rawExpr(&x, call, nil) {
+	case conversion:
+		msg = "requires function call, not conversion"
+	case expression:
+		msg = "discards result of"
+	case statement:
+		return
+	default:
+		unreachable()
+	}
+	check.errorf(x.pos(), "%s %s %s", keyword, msg, &x)
+}
+
+func (check *Checker) caseValues(x operand /* copy argument (not *operand!) */, values []ast.Expr) {
+	// No duplicate checking for now. See issue 4524.
+	for _, e := range values {
+		var y operand
+		check.expr(&y, e)
+		if y.mode == invalid {
+			return
+		}
+		// TODO(gri) The convertUntyped call pair below appears in other places. Factor!
+		// Order matters: By comparing y against x, error positions are at the case values.
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			return
+		}
+		check.convertUntyped(&x, y.typ)
+		if x.mode == invalid {
+			return
+		}
+		check.comparison(&y, &x, token.EQL)
+	}
+}
+
+func (check *Checker) caseTypes(x *operand, xtyp *Interface, types []ast.Expr, seen map[Type]token.Pos) (T Type) {
+L:
+	for _, e := range types {
+		T = check.typOrNil(e)
+		if T == Typ[Invalid] {
+			continue
+		}
+		// complain about duplicate types
+		// TODO(gri) use a type hash to avoid quadratic algorithm
+		for t, pos := range seen {
+			if T == nil && t == nil || T != nil && t != nil && Identical(T, t) {
+				// talk about "case" rather than "type" because of nil case
+				check.error(e.Pos(), "duplicate case in type switch")
+				check.errorf(pos, "\tprevious case %s", T) // secondary error, \t indented
+				continue L
+			}
+		}
+		seen[T] = e.Pos()
+		if T != nil {
+			check.typeAssertion(e.Pos(), x, xtyp, T)
+		}
+	}
+	return
+}
+
+// stmt typechecks statement s.
+func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
+	// statements cannot use iota in general
+	// (constant declarations set it explicitly)
+	assert(check.iota == nil)
+
+	// statements must end with the same top scope as they started with
+	if debug {
+		defer func(scope *Scope) {
+			// don't check if code is panicking
+			if p := recover(); p != nil {
+				panic(p)
+			}
+			assert(scope == check.scope)
+		}(check.scope)
+	}
+
+	inner := ctxt &^ fallthroughOk
+	switch s := s.(type) {
+	case *ast.BadStmt, *ast.EmptyStmt:
+		// ignore
+
+	case *ast.DeclStmt:
+		check.declStmt(s.Decl)
+
+	case *ast.LabeledStmt:
+		check.hasLabel = true
+		check.stmt(ctxt, s.Stmt)
+
+	case *ast.ExprStmt:
+		// spec: "With the exception of specific built-in functions,
+		// function and method calls and receive operations can appear
+		// in statement context. Such statements may be parenthesized."
+		var x operand
+		kind := check.rawExpr(&x, s.X, nil)
+		var msg string
+		switch x.mode {
+		default:
+			if kind == statement {
+				return
+			}
+			msg = "is not used"
+		case builtin:
+			msg = "must be called"
+		case typexpr:
+			msg = "is not an expression"
+		}
+		check.errorf(x.pos(), "%s %s", &x, msg)
+
+	case *ast.SendStmt:
+		var ch, x operand
+		check.expr(&ch, s.Chan)
+		check.expr(&x, s.Value)
+		if ch.mode == invalid || x.mode == invalid {
+			return
+		}
+		if tch, ok := ch.typ.Underlying().(*Chan); !ok || tch.dir == RecvOnly || !check.assignment(&x, tch.elem) {
+			if x.mode != invalid {
+				check.invalidOp(ch.pos(), "cannot send %s to channel %s", &x, &ch)
+			}
+		}
+
+	case *ast.IncDecStmt:
+		var op token.Token
+		switch s.Tok {
+		case token.INC:
+			op = token.ADD
+		case token.DEC:
+			op = token.SUB
+		default:
+			check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
+			return
+		}
+		var x operand
+		Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
+		check.binary(&x, nil, s.X, Y, op)
+		if x.mode == invalid {
+			return
+		}
+		check.assignVar(s.X, &x)
+
+	case *ast.AssignStmt:
+		switch s.Tok {
+		case token.ASSIGN, token.DEFINE:
+			if len(s.Lhs) == 0 {
+				check.invalidAST(s.Pos(), "missing lhs in assignment")
+				return
+			}
+			if s.Tok == token.DEFINE {
+				check.shortVarDecl(s.TokPos, s.Lhs, s.Rhs)
+			} else {
+				// regular assignment
+				check.assignVars(s.Lhs, s.Rhs)
+			}
+
+		default:
+			// assignment operations
+			if len(s.Lhs) != 1 || len(s.Rhs) != 1 {
+				check.errorf(s.TokPos, "assignment operation %s requires single-valued expressions", s.Tok)
+				return
+			}
+			op := assignOp(s.Tok)
+			if op == token.ILLEGAL {
+				check.invalidAST(s.TokPos, "unknown assignment operation %s", s.Tok)
+				return
+			}
+			var x operand
+			check.binary(&x, nil, s.Lhs[0], s.Rhs[0], op)
+			if x.mode == invalid {
+				return
+			}
+			check.assignVar(s.Lhs[0], &x)
+		}
+
+	case *ast.GoStmt:
+		check.suspendedCall("go", s.Call)
+
+	case *ast.DeferStmt:
+		check.suspendedCall("defer", s.Call)
+
+	case *ast.ReturnStmt:
+		res := check.sig.results
+		if res.Len() > 0 {
+			// function returns results
+			// (if one, say the first, result parameter is named, all of them are named)
+			if len(s.Results) == 0 && res.vars[0].name != "" {
+				// spec: "Implementation restriction: A compiler may disallow an empty expression
+				// list in a "return" statement if a different entity (constant, type, or variable)
+				// with the same name as a result parameter is in scope at the place of the return."
+				for _, obj := range res.vars {
+					if _, alt := check.scope.LookupParent(obj.name, check.pos); alt != nil && alt != obj {
+						check.errorf(s.Pos(), "result parameter %s not in scope at return", obj.name)
+						check.errorf(alt.Pos(), "\tinner declaration of %s", obj)
+						// ok to continue
+					}
+				}
+			} else {
+				// return has results or result parameters are unnamed
+				check.initVars(res.vars, s.Results, s.Return)
+			}
+		} else if len(s.Results) > 0 {
+			check.error(s.Results[0].Pos(), "no result values expected")
+			check.use(s.Results...)
+		}
+
+	case *ast.BranchStmt:
+		if s.Label != nil {
+			check.hasLabel = true
+			return // checked in 2nd pass (check.labels)
+		}
+		switch s.Tok {
+		case token.BREAK:
+			if ctxt&breakOk == 0 {
+				check.error(s.Pos(), "break not in for, switch, or select statement")
+			}
+		case token.CONTINUE:
+			if ctxt&continueOk == 0 {
+				check.error(s.Pos(), "continue not in for statement")
+			}
+		case token.FALLTHROUGH:
+			if ctxt&fallthroughOk == 0 {
+				check.error(s.Pos(), "fallthrough statement out of place")
+			}
+		default:
+			check.invalidAST(s.Pos(), "branch statement: %s", s.Tok)
+		}
+
+	case *ast.BlockStmt:
+		check.openScope(s, "block")
+		defer check.closeScope()
+
+		check.stmtList(inner, s.List)
+
+	case *ast.IfStmt:
+		check.openScope(s, "if")
+		defer check.closeScope()
+
+		check.simpleStmt(s.Init)
+		var x operand
+		check.expr(&x, s.Cond)
+		if x.mode != invalid && !isBoolean(x.typ) {
+			check.error(s.Cond.Pos(), "non-boolean condition in if statement")
+		}
+		check.stmt(inner, s.Body)
+		if s.Else != nil {
+			check.stmt(inner, s.Else)
+		}
+
+	case *ast.SwitchStmt:
+		inner |= breakOk
+		check.openScope(s, "switch")
+		defer check.closeScope()
+
+		check.simpleStmt(s.Init)
+		var x operand
+		if s.Tag != nil {
+			check.expr(&x, s.Tag)
+		} else {
+			// spec: "A missing switch expression is
+			// equivalent to the boolean value true."
+			x.mode = constant_
+			x.typ = Typ[Bool]
+			x.val = constant.MakeBool(true)
+			x.expr = &ast.Ident{NamePos: s.Body.Lbrace, Name: "true"}
+		}
+
+		check.multipleDefaults(s.Body.List)
+
+		for i, c := range s.Body.List {
+			clause, _ := c.(*ast.CaseClause)
+			if clause == nil {
+				check.invalidAST(c.Pos(), "incorrect expression switch case")
+				continue
+			}
+			if x.mode != invalid {
+				check.caseValues(x, clause.List)
+			}
+			check.openScope(clause, "case")
+			inner := inner
+			if i+1 < len(s.Body.List) {
+				inner |= fallthroughOk
+			}
+			check.stmtList(inner, clause.Body)
+			check.closeScope()
+		}
+
+	case *ast.TypeSwitchStmt:
+		inner |= breakOk
+		check.openScope(s, "type switch")
+		defer check.closeScope()
+
+		check.simpleStmt(s.Init)
+
+		// A type switch guard must be of the form:
+		//
+		//     TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
+		//
+		// The parser is checking syntactic correctness;
+		// remaining syntactic errors are considered AST errors here.
+		// TODO(gri) better factoring of error handling (invalid ASTs)
+		//
+		var lhs *ast.Ident // lhs identifier or nil
+		var rhs ast.Expr
+		switch guard := s.Assign.(type) {
+		case *ast.ExprStmt:
+			rhs = guard.X
+		case *ast.AssignStmt:
+			if len(guard.Lhs) != 1 || guard.Tok != token.DEFINE || len(guard.Rhs) != 1 {
+				check.invalidAST(s.Pos(), "incorrect form of type switch guard")
+				return
+			}
+
+			lhs, _ = guard.Lhs[0].(*ast.Ident)
+			if lhs == nil {
+				check.invalidAST(s.Pos(), "incorrect form of type switch guard")
+				return
+			}
+
+			if lhs.Name == "_" {
+				// _ := x.(type) is an invalid short variable declaration
+				check.softErrorf(lhs.Pos(), "no new variable on left side of :=")
+				lhs = nil // avoid declared but not used error below
+			} else {
+				check.recordDef(lhs, nil) // lhs variable is implicitly declared in each cause clause
+			}
+
+			rhs = guard.Rhs[0]
+
+		default:
+			check.invalidAST(s.Pos(), "incorrect form of type switch guard")
+			return
+		}
+
+		// rhs must be of the form: expr.(type) and expr must be an interface
+		expr, _ := rhs.(*ast.TypeAssertExpr)
+		if expr == nil || expr.Type != nil {
+			check.invalidAST(s.Pos(), "incorrect form of type switch guard")
+			return
+		}
+		var x operand
+		check.expr(&x, expr.X)
+		if x.mode == invalid {
+			return
+		}
+		xtyp, _ := x.typ.Underlying().(*Interface)
+		if xtyp == nil {
+			check.errorf(x.pos(), "%s is not an interface", &x)
+			return
+		}
+
+		check.multipleDefaults(s.Body.List)
+
+		var lhsVars []*Var               // list of implicitly declared lhs variables
+		seen := make(map[Type]token.Pos) // map of seen types to positions
+		for _, s := range s.Body.List {
+			clause, _ := s.(*ast.CaseClause)
+			if clause == nil {
+				check.invalidAST(s.Pos(), "incorrect type switch case")
+				continue
+			}
+			// Check each type in this type switch case.
+			T := check.caseTypes(&x, xtyp, clause.List, seen)
+			check.openScope(clause, "case")
+			// If lhs exists, declare a corresponding variable in the case-local scope.
+			if lhs != nil {
+				// spec: "The TypeSwitchGuard may include a short variable declaration.
+				// When that form is used, the variable is declared at the beginning of
+				// the implicit block in each clause. In clauses with a case listing
+				// exactly one type, the variable has that type; otherwise, the variable
+				// has the type of the expression in the TypeSwitchGuard."
+				if len(clause.List) != 1 || T == nil {
+					T = x.typ
+				}
+				obj := NewVar(lhs.Pos(), check.pkg, lhs.Name, T)
+				scopePos := clause.End()
+				if len(clause.Body) > 0 {
+					scopePos = clause.Body[0].Pos()
+				}
+				check.declare(check.scope, nil, obj, scopePos)
+				check.recordImplicit(clause, obj)
+				// For the "declared but not used" error, all lhs variables act as
+				// one; i.e., if any one of them is 'used', all of them are 'used'.
+				// Collect them for later analysis.
+				lhsVars = append(lhsVars, obj)
+			}
+			check.stmtList(inner, clause.Body)
+			check.closeScope()
+		}
+
+		// If lhs exists, we must have at least one lhs variable that was used.
+		if lhs != nil {
+			var used bool
+			for _, v := range lhsVars {
+				if v.used {
+					used = true
+				}
+				v.used = true // avoid usage error when checking entire function
+			}
+			if !used {
+				check.softErrorf(lhs.Pos(), "%s declared but not used", lhs.Name)
+			}
+		}
+
+	case *ast.SelectStmt:
+		inner |= breakOk
+
+		check.multipleDefaults(s.Body.List)
+
+		for _, s := range s.Body.List {
+			clause, _ := s.(*ast.CommClause)
+			if clause == nil {
+				continue // error reported before
+			}
+
+			// clause.Comm must be a SendStmt, RecvStmt, or default case
+			valid := false
+			var rhs ast.Expr // rhs of RecvStmt, or nil
+			switch s := clause.Comm.(type) {
+			case nil, *ast.SendStmt:
+				valid = true
+			case *ast.AssignStmt:
+				if len(s.Rhs) == 1 {
+					rhs = s.Rhs[0]
+				}
+			case *ast.ExprStmt:
+				rhs = s.X
+			}
+
+			// if present, rhs must be a receive operation
+			if rhs != nil {
+				if x, _ := unparen(rhs).(*ast.UnaryExpr); x != nil && x.Op == token.ARROW {
+					valid = true
+				}
+			}
+
+			if !valid {
+				check.error(clause.Comm.Pos(), "select case must be send or receive (possibly with assignment)")
+				continue
+			}
+
+			check.openScope(s, "case")
+			if clause.Comm != nil {
+				check.stmt(inner, clause.Comm)
+			}
+			check.stmtList(inner, clause.Body)
+			check.closeScope()
+		}
+
+	case *ast.ForStmt:
+		inner |= breakOk | continueOk
+		check.openScope(s, "for")
+		defer check.closeScope()
+
+		check.simpleStmt(s.Init)
+		if s.Cond != nil {
+			var x operand
+			check.expr(&x, s.Cond)
+			if x.mode != invalid && !isBoolean(x.typ) {
+				check.error(s.Cond.Pos(), "non-boolean condition in for statement")
+			}
+		}
+		check.simpleStmt(s.Post)
+		// spec: "The init statement may be a short variable
+		// declaration, but the post statement must not."
+		if s, _ := s.Post.(*ast.AssignStmt); s != nil && s.Tok == token.DEFINE {
+			check.softErrorf(s.Pos(), "cannot declare in post statement")
+			check.use(s.Lhs...) // avoid follow-up errors
+		}
+		check.stmt(inner, s.Body)
+
+	case *ast.RangeStmt:
+		inner |= breakOk | continueOk
+		check.openScope(s, "for")
+		defer check.closeScope()
+
+		// check expression to iterate over
+		var x operand
+		check.expr(&x, s.X)
+
+		// determine key/value types
+		var key, val Type
+		if x.mode != invalid {
+			switch typ := x.typ.Underlying().(type) {
+			case *Basic:
+				if isString(typ) {
+					key = Typ[Int]
+					val = universeRune // use 'rune' name
+				}
+			case *Array:
+				key = Typ[Int]
+				val = typ.elem
+			case *Slice:
+				key = Typ[Int]
+				val = typ.elem
+			case *Pointer:
+				if typ, _ := typ.base.Underlying().(*Array); typ != nil {
+					key = Typ[Int]
+					val = typ.elem
+				}
+			case *Map:
+				key = typ.key
+				val = typ.elem
+			case *Chan:
+				key = typ.elem
+				val = Typ[Invalid]
+				if typ.dir == SendOnly {
+					check.errorf(x.pos(), "cannot range over send-only channel %s", &x)
+					// ok to continue
+				}
+				if s.Value != nil {
+					check.errorf(s.Value.Pos(), "iteration over %s permits only one iteration variable", &x)
+					// ok to continue
+				}
+			}
+		}
+
+		if key == nil {
+			check.errorf(x.pos(), "cannot range over %s", &x)
+			// ok to continue
+		}
+
+		// check assignment to/declaration of iteration variables
+		// (irregular assignment, cannot easily map to existing assignment checks)
+
+		// lhs expressions and initialization value (rhs) types
+		lhs := [2]ast.Expr{s.Key, s.Value}
+		rhs := [2]Type{key, val} // key, val may be nil
+
+		if s.Tok == token.DEFINE {
+			// short variable declaration; variable scope starts after the range clause
+			// (the for loop opens a new scope, so variables on the lhs never redeclare
+			// previously declared variables)
+			var vars []*Var
+			for i, lhs := range lhs {
+				if lhs == nil {
+					continue
+				}
+
+				// determine lhs variable
+				var obj *Var
+				if ident, _ := lhs.(*ast.Ident); ident != nil {
+					// declare new variable
+					name := ident.Name
+					obj = NewVar(ident.Pos(), check.pkg, name, nil)
+					check.recordDef(ident, obj)
+					// _ variables don't count as new variables
+					if name != "_" {
+						vars = append(vars, obj)
+					}
+				} else {
+					check.errorf(lhs.Pos(), "cannot declare %s", lhs)
+					obj = NewVar(lhs.Pos(), check.pkg, "_", nil) // dummy variable
+				}
+
+				// initialize lhs variable
+				if typ := rhs[i]; typ != nil {
+					x.mode = value
+					x.expr = lhs // we don't have a better rhs expression to use here
+					x.typ = typ
+					check.initVar(obj, &x, false)
+				} else {
+					obj.typ = Typ[Invalid]
+					obj.used = true // don't complain about unused variable
+				}
+			}
+
+			// declare variables
+			if len(vars) > 0 {
+				for _, obj := range vars {
+					// spec: "The scope of a constant or variable identifier declared inside
+					// a function begins at the end of the ConstSpec or VarSpec (ShortVarDecl
+					// for short variable declarations) and ends at the end of the innermost
+					// containing block."
+					scopePos := s.End()
+					check.declare(check.scope, nil /* recordDef already called */, obj, scopePos)
+				}
+			} else {
+				check.error(s.TokPos, "no new variables on left side of :=")
+			}
+		} else {
+			// ordinary assignment
+			for i, lhs := range lhs {
+				if lhs == nil {
+					continue
+				}
+				if typ := rhs[i]; typ != nil {
+					x.mode = value
+					x.expr = lhs // we don't have a better rhs expression to use here
+					x.typ = typ
+					check.assignVar(lhs, &x)
+				}
+			}
+		}
+
+		check.stmt(inner, s.Body)
+
+	default:
+		check.error(s.Pos(), "invalid statement")
+	}
+}
diff --git a/libgo/go/go/types/token_test.go b/libgo/go/go/types/token_test.go
new file mode 100644
index 00000000000..705bb295a16
--- /dev/null
+++ b/libgo/go/go/types/token_test.go
@@ -0,0 +1,47 @@
+// Copyright 2013 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.
+
+// This file checks invariants of token.Token ordering that we rely on
+// since package go/token doesn't provide any guarantees at the moment.
+
+package types
+
+import (
+	"go/token"
+	"testing"
+)
+
+var assignOps = map[token.Token]token.Token{
+	token.ADD_ASSIGN:     token.ADD,
+	token.SUB_ASSIGN:     token.SUB,
+	token.MUL_ASSIGN:     token.MUL,
+	token.QUO_ASSIGN:     token.QUO,
+	token.REM_ASSIGN:     token.REM,
+	token.AND_ASSIGN:     token.AND,
+	token.OR_ASSIGN:      token.OR,
+	token.XOR_ASSIGN:     token.XOR,
+	token.SHL_ASSIGN:     token.SHL,
+	token.SHR_ASSIGN:     token.SHR,
+	token.AND_NOT_ASSIGN: token.AND_NOT,
+}
+
+func TestZeroTok(t *testing.T) {
+	// zero value for token.Token must be token.ILLEGAL
+	var zero token.Token
+	if token.ILLEGAL != zero {
+		t.Errorf("%s == %d; want 0", token.ILLEGAL, zero)
+	}
+}
+
+func TestAssignOp(t *testing.T) {
+	// there are fewer than 256 tokens
+	for i := 0; i < 256; i++ {
+		tok := token.Token(i)
+		got := assignOp(tok)
+		want := assignOps[tok]
+		if got != want {
+			t.Errorf("for assignOp(%s): got %s; want %s", tok, got, want)
+		}
+	}
+}
diff --git a/libgo/go/go/types/type.go b/libgo/go/go/types/type.go
new file mode 100644
index 00000000000..1df8b45b285
--- /dev/null
+++ b/libgo/go/go/types/type.go
@@ -0,0 +1,454 @@
+// 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.
+
+package types
+
+import "sort"
+
+// TODO(gri) Revisit factory functions - make sure they have all relevant parameters.
+
+// A Type represents a type of Go.
+// All types implement the Type interface.
+type Type interface {
+	// Underlying returns the underlying type of a type.
+	Underlying() Type
+
+	// String returns a string representation of a type.
+	String() string
+}
+
+// BasicKind describes the kind of basic type.
+type BasicKind int
+
+const (
+	Invalid BasicKind = iota // type is invalid
+
+	// predeclared types
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	String
+	UnsafePointer
+
+	// types for untyped values
+	UntypedBool
+	UntypedInt
+	UntypedRune
+	UntypedFloat
+	UntypedComplex
+	UntypedString
+	UntypedNil
+
+	// aliases
+	Byte = Uint8
+	Rune = Int32
+)
+
+// BasicInfo is a set of flags describing properties of a basic type.
+type BasicInfo int
+
+// Properties of basic types.
+const (
+	IsBoolean BasicInfo = 1 << iota
+	IsInteger
+	IsUnsigned
+	IsFloat
+	IsComplex
+	IsString
+	IsUntyped
+
+	IsOrdered   = IsInteger | IsFloat | IsString
+	IsNumeric   = IsInteger | IsFloat | IsComplex
+	IsConstType = IsBoolean | IsNumeric | IsString
+)
+
+// A Basic represents a basic type.
+type Basic struct {
+	kind BasicKind
+	info BasicInfo
+	name string
+}
+
+// Kind returns the kind of basic type b.
+func (b *Basic) Kind() BasicKind { return b.kind }
+
+// Info returns information about properties of basic type b.
+func (b *Basic) Info() BasicInfo { return b.info }
+
+// Name returns the name of basic type b.
+func (b *Basic) Name() string { return b.name }
+
+// An Array represents an array type.
+type Array struct {
+	len  int64
+	elem Type
+}
+
+// NewArray returns a new array type for the given element type and length.
+func NewArray(elem Type, len int64) *Array { return &Array{len, elem} }
+
+// Len returns the length of array a.
+func (a *Array) Len() int64 { return a.len }
+
+// Elem returns element type of array a.
+func (a *Array) Elem() Type { return a.elem }
+
+// A Slice represents a slice type.
+type Slice struct {
+	elem Type
+}
+
+// NewSlice returns a new slice type for the given element type.
+func NewSlice(elem Type) *Slice { return &Slice{elem} }
+
+// Elem returns the element type of slice s.
+func (s *Slice) Elem() Type { return s.elem }
+
+// A Struct represents a struct type.
+type Struct struct {
+	fields []*Var
+	tags   []string // field tags; nil if there are no tags
+	// TODO(gri) access to offsets is not threadsafe - fix this
+	offsets []int64 // field offsets in bytes, lazily initialized
+}
+
+// NewStruct returns a new struct with the given fields and corresponding field tags.
+// If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be
+// only as long as required to hold the tag with the largest index i. Consequently,
+// if no field has a tag, tags may be nil.
+func NewStruct(fields []*Var, tags []string) *Struct {
+	var fset objset
+	for _, f := range fields {
+		if f.name != "_" && fset.insert(f) != nil {
+			panic("multiple fields with the same name")
+		}
+	}
+	if len(tags) > len(fields) {
+		panic("more tags than fields")
+	}
+	return &Struct{fields: fields, tags: tags}
+}
+
+// NumFields returns the number of fields in the struct (including blank and anonymous fields).
+func (s *Struct) NumFields() int { return len(s.fields) }
+
+// Field returns the i'th field for 0 <= i < NumFields().
+func (s *Struct) Field(i int) *Var { return s.fields[i] }
+
+// Tag returns the i'th field tag for 0 <= i < NumFields().
+func (s *Struct) Tag(i int) string {
+	if i < len(s.tags) {
+		return s.tags[i]
+	}
+	return ""
+}
+
+// A Pointer represents a pointer type.
+type Pointer struct {
+	base Type // element type
+}
+
+// NewPointer returns a new pointer type for the given element (base) type.
+func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} }
+
+// Elem returns the element type for the given pointer p.
+func (p *Pointer) Elem() Type { return p.base }
+
+// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple.
+// Tuples are used as components of signatures and to represent the type of multiple
+// assignments; they are not first class types of Go.
+type Tuple struct {
+	vars []*Var
+}
+
+// NewTuple returns a new tuple for the given variables.
+func NewTuple(x ...*Var) *Tuple {
+	if len(x) > 0 {
+		return &Tuple{x}
+	}
+	return nil
+}
+
+// Len returns the number variables of tuple t.
+func (t *Tuple) Len() int {
+	if t != nil {
+		return len(t.vars)
+	}
+	return 0
+}
+
+// At returns the i'th variable of tuple t.
+func (t *Tuple) At(i int) *Var { return t.vars[i] }
+
+// A Signature represents a (non-builtin) function or method type.
+type Signature struct {
+	// We need to keep the scope in Signature (rather than passing it around
+	// and store it in the Func Object) because when type-checking a function
+	// literal we call the general type checker which returns a general Type.
+	// We then unpack the *Signature and use the scope for the literal body.
+	scope    *Scope // function scope, present for package-local signatures
+	recv     *Var   // nil if not a method
+	params   *Tuple // (incoming) parameters from left to right; or nil
+	results  *Tuple // (outgoing) results from left to right; or nil
+	variadic bool   // true if the last parameter's type is of the form ...T (or string, for append built-in only)
+}
+
+// NewSignature returns a new function type for the given receiver, parameters,
+// and results, either of which may be nil. If variadic is set, the function
+// is variadic, it must have at least one parameter, and the last parameter
+// must be of unnamed slice type.
+func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
+	if variadic {
+		n := params.Len()
+		if n == 0 {
+			panic("types.NewSignature: variadic function must have at least one parameter")
+		}
+		if _, ok := params.At(n - 1).typ.(*Slice); !ok {
+			panic("types.NewSignature: variadic parameter must be of unnamed slice type")
+		}
+	}
+	return &Signature{nil, recv, params, results, variadic}
+}
+
+// Recv returns the receiver of signature s (if a method), or nil if a
+// function.
+//
+// For an abstract method, Recv returns the enclosing interface either
+// as a *Named or an *Interface.  Due to embedding, an interface may
+// contain methods whose receiver type is a different interface.
+func (s *Signature) Recv() *Var { return s.recv }
+
+// Params returns the parameters of signature s, or nil.
+func (s *Signature) Params() *Tuple { return s.params }
+
+// Results returns the results of signature s, or nil.
+func (s *Signature) Results() *Tuple { return s.results }
+
+// Variadic reports whether the signature s is variadic.
+func (s *Signature) Variadic() bool { return s.variadic }
+
+// An Interface represents an interface type.
+type Interface struct {
+	methods   []*Func  // ordered list of explicitly declared methods
+	embeddeds []*Named // ordered list of explicitly embedded types
+
+	allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
+}
+
+// NewInterface returns a new interface for the given methods and embedded types.
+func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
+	typ := new(Interface)
+
+	var mset objset
+	for _, m := range methods {
+		if mset.insert(m) != nil {
+			panic("multiple methods with the same name")
+		}
+		// set receiver
+		// TODO(gri) Ideally, we should use a named type here instead of
+		// typ, for less verbose printing of interface method signatures.
+		m.typ.(*Signature).recv = NewVar(m.pos, m.pkg, "", typ)
+	}
+	sort.Sort(byUniqueMethodName(methods))
+
+	if embeddeds == nil {
+		sort.Sort(byUniqueTypeName(embeddeds))
+	}
+
+	typ.methods = methods
+	typ.embeddeds = embeddeds
+	return typ
+}
+
+// NumExplicitMethods returns the number of explicitly declared methods of interface t.
+func (t *Interface) NumExplicitMethods() int { return len(t.methods) }
+
+// ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) ExplicitMethod(i int) *Func { return t.methods[i] }
+
+// NumEmbeddeds returns the number of embedded types in interface t.
+func (t *Interface) NumEmbeddeds() int { return len(t.embeddeds) }
+
+// Embedded returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds().
+// The types are ordered by the corresponding TypeName's unique Id.
+func (t *Interface) Embedded(i int) *Named { return t.embeddeds[i] }
+
+// NumMethods returns the total number of methods of interface t.
+func (t *Interface) NumMethods() int { return len(t.allMethods) }
+
+// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
+// The methods are ordered by their unique Id.
+func (t *Interface) Method(i int) *Func { return t.allMethods[i] }
+
+// Empty returns true if t is the empty interface.
+func (t *Interface) Empty() bool { return len(t.allMethods) == 0 }
+
+// Complete computes the interface's method set. It must be called by users of
+// NewInterface after the interface's embedded types are fully defined and
+// before using the interface type in any way other than to form other types.
+// Complete returns the receiver.
+func (t *Interface) Complete() *Interface {
+	if t.allMethods != nil {
+		return t
+	}
+
+	var allMethods []*Func
+	if t.embeddeds == nil {
+		if t.methods == nil {
+			allMethods = make([]*Func, 0, 1)
+		} else {
+			allMethods = t.methods
+		}
+	} else {
+		allMethods = append(allMethods, t.methods...)
+		for _, et := range t.embeddeds {
+			it := et.Underlying().(*Interface)
+			it.Complete()
+			for _, tm := range it.allMethods {
+				// Make a copy of the method and adjust its receiver type.
+				newm := *tm
+				newmtyp := *tm.typ.(*Signature)
+				newm.typ = &newmtyp
+				newmtyp.recv = NewVar(newm.pos, newm.pkg, "", t)
+				allMethods = append(allMethods, &newm)
+			}
+		}
+		sort.Sort(byUniqueMethodName(allMethods))
+	}
+	t.allMethods = allMethods
+
+	return t
+}
+
+// A Map represents a map type.
+type Map struct {
+	key, elem Type
+}
+
+// NewMap returns a new map for the given key and element types.
+func NewMap(key, elem Type) *Map {
+	return &Map{key, elem}
+}
+
+// Key returns the key type of map m.
+func (m *Map) Key() Type { return m.key }
+
+// Elem returns the element type of map m.
+func (m *Map) Elem() Type { return m.elem }
+
+// A Chan represents a channel type.
+type Chan struct {
+	dir  ChanDir
+	elem Type
+}
+
+// A ChanDir value indicates a channel direction.
+type ChanDir int
+
+// The direction of a channel is indicated by one of the following constants.
+const (
+	SendRecv ChanDir = iota
+	SendOnly
+	RecvOnly
+)
+
+// NewChan returns a new channel type for the given direction and element type.
+func NewChan(dir ChanDir, elem Type) *Chan {
+	return &Chan{dir, elem}
+}
+
+// Dir returns the direction of channel c.
+func (c *Chan) Dir() ChanDir { return c.dir }
+
+// Elem returns the element type of channel c.
+func (c *Chan) Elem() Type { return c.elem }
+
+// A Named represents a named type.
+type Named struct {
+	obj        *TypeName // corresponding declared object
+	underlying Type      // possibly a *Named during setup; never a *Named once set up completely
+	methods    []*Func   // methods declared for this type (not the method set of this type)
+}
+
+// NewNamed returns a new named type for the given type name, underlying type, and associated methods.
+// The underlying type must not be a *Named.
+func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named {
+	if _, ok := underlying.(*Named); ok {
+		panic("types.NewNamed: underlying type must not be *Named")
+	}
+	typ := &Named{obj: obj, underlying: underlying, methods: methods}
+	if obj.typ == nil {
+		obj.typ = typ
+	}
+	return typ
+}
+
+// TypeName returns the type name for the named type t.
+func (t *Named) Obj() *TypeName { return t.obj }
+
+// NumMethods returns the number of explicit methods whose receiver is named type t.
+func (t *Named) NumMethods() int { return len(t.methods) }
+
+// Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
+func (t *Named) Method(i int) *Func { return t.methods[i] }
+
+// SetUnderlying sets the underlying type and marks t as complete.
+// TODO(gri) determine if there's a better solution rather than providing this function
+func (t *Named) SetUnderlying(underlying Type) {
+	if underlying == nil {
+		panic("types.Named.SetUnderlying: underlying type must not be nil")
+	}
+	if _, ok := underlying.(*Named); ok {
+		panic("types.Named.SetUnderlying: underlying type must not be *Named")
+	}
+	t.underlying = underlying
+}
+
+// AddMethod adds method m unless it is already in the method list.
+// TODO(gri) find a better solution instead of providing this function
+func (t *Named) AddMethod(m *Func) {
+	if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 {
+		t.methods = append(t.methods, m)
+	}
+}
+
+// Implementations for Type methods.
+
+func (t *Basic) Underlying() Type     { return t }
+func (t *Array) Underlying() Type     { return t }
+func (t *Slice) Underlying() Type     { return t }
+func (t *Struct) Underlying() Type    { return t }
+func (t *Pointer) Underlying() Type   { return t }
+func (t *Tuple) Underlying() Type     { return t }
+func (t *Signature) Underlying() Type { return t }
+func (t *Interface) Underlying() Type { return t }
+func (t *Map) Underlying() Type       { return t }
+func (t *Chan) Underlying() Type      { return t }
+func (t *Named) Underlying() Type     { return t.underlying }
+
+func (t *Basic) String() string     { return TypeString(t, nil) }
+func (t *Array) String() string     { return TypeString(t, nil) }
+func (t *Slice) String() string     { return TypeString(t, nil) }
+func (t *Struct) String() string    { return TypeString(t, nil) }
+func (t *Pointer) String() string   { return TypeString(t, nil) }
+func (t *Tuple) String() string     { return TypeString(t, nil) }
+func (t *Signature) String() string { return TypeString(t, nil) }
+func (t *Interface) String() string { return TypeString(t, nil) }
+func (t *Map) String() string       { return TypeString(t, nil) }
+func (t *Chan) String() string      { return TypeString(t, nil) }
+func (t *Named) String() string     { return TypeString(t, nil) }
diff --git a/libgo/go/go/types/typestring.go b/libgo/go/go/types/typestring.go
new file mode 100644
index 00000000000..bd62f4dc229
--- /dev/null
+++ b/libgo/go/go/types/typestring.go
@@ -0,0 +1,296 @@
+// Copyright 2013 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.
+
+// This file implements printing of types.
+
+package types
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// A Qualifier controls how named package-level objects are printed in
+// calls to TypeString, ObjectString, and SelectionString.
+//
+// These three formatting routines call the Qualifier for each
+// package-level object O, and if the Qualifier returns a non-empty
+// string p, the object is printed in the form p.O.
+// If it returns an empty string, only the object name O is printed.
+//
+// Using a nil Qualifier is equivalent to using (*Package).Path: the
+// object is qualified by the import path, e.g., "encoding/json.Marshal".
+//
+type Qualifier func(*Package) string
+
+// RelativeTo(pkg) returns a Qualifier that fully qualifies members of
+// all packages other than pkg.
+func RelativeTo(pkg *Package) Qualifier {
+	if pkg == nil {
+		return nil
+	}
+	return func(other *Package) string {
+		if pkg == other {
+			return "" // same package; unqualified
+		}
+		return other.Path()
+	}
+}
+
+// If gcCompatibilityMode is set, printing of types is modified
+// to match the representation of some types in the gc compiler:
+//
+//	- byte and rune lose their alias name and simply stand for
+//	  uint8 and int32 respectively
+//	- embedded interfaces get flattened (the embedding info is lost,
+//	  and certain recursive interface types cannot be printed anymore)
+//
+// This makes it easier to compare packages computed with the type-
+// checker vs packages imported from gc export data.
+//
+// Caution: This flag affects all uses of WriteType, globally.
+// It is only provided for testing in conjunction with
+// gc-generated data.
+//
+// This flag is exported in the x/tools/go/types package. We don't
+// need it at the moment in the std repo and so we don't export it
+// anymore. We should eventually try to remove it altogether.
+var gcCompatibilityMode bool
+
+// TypeString returns the string representation of typ.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func TypeString(typ Type, qf Qualifier) string {
+	var buf bytes.Buffer
+	WriteType(&buf, typ, qf)
+	return buf.String()
+}
+
+// WriteType writes the string representation of typ to buf.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func WriteType(buf *bytes.Buffer, typ Type, qf Qualifier) {
+	writeType(buf, typ, qf, make([]Type, 8))
+}
+
+func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
+	// Theoretically, this is a quadratic lookup algorithm, but in
+	// practice deeply nested composite types with unnamed component
+	// types are uncommon. This code is likely more efficient than
+	// using a map.
+	for _, t := range visited {
+		if t == typ {
+			fmt.Fprintf(buf, "○%T", typ) // cycle to typ
+			return
+		}
+	}
+	visited = append(visited, typ)
+
+	switch t := typ.(type) {
+	case nil:
+		buf.WriteString("<nil>")
+
+	case *Basic:
+		if t.kind == UnsafePointer {
+			buf.WriteString("unsafe.")
+		}
+		if gcCompatibilityMode {
+			// forget the alias names
+			switch t.kind {
+			case Byte:
+				t = Typ[Uint8]
+			case Rune:
+				t = Typ[Int32]
+			}
+		}
+		buf.WriteString(t.name)
+
+	case *Array:
+		fmt.Fprintf(buf, "[%d]", t.len)
+		writeType(buf, t.elem, qf, visited)
+
+	case *Slice:
+		buf.WriteString("[]")
+		writeType(buf, t.elem, qf, visited)
+
+	case *Struct:
+		buf.WriteString("struct{")
+		for i, f := range t.fields {
+			if i > 0 {
+				buf.WriteString("; ")
+			}
+			if !f.anonymous {
+				buf.WriteString(f.name)
+				buf.WriteByte(' ')
+			}
+			writeType(buf, f.typ, qf, visited)
+			if tag := t.Tag(i); tag != "" {
+				fmt.Fprintf(buf, " %q", tag)
+			}
+		}
+		buf.WriteByte('}')
+
+	case *Pointer:
+		buf.WriteByte('*')
+		writeType(buf, t.base, qf, visited)
+
+	case *Tuple:
+		writeTuple(buf, t, false, qf, visited)
+
+	case *Signature:
+		buf.WriteString("func")
+		writeSignature(buf, t, qf, visited)
+
+	case *Interface:
+		// We write the source-level methods and embedded types rather
+		// than the actual method set since resolved method signatures
+		// may have non-printable cycles if parameters have anonymous
+		// interface types that (directly or indirectly) embed the
+		// current interface. For instance, consider the result type
+		// of m:
+		//
+		//     type T interface{
+		//         m() interface{ T }
+		//     }
+		//
+		buf.WriteString("interface{")
+		if gcCompatibilityMode {
+			// print flattened interface
+			// (useful to compare against gc-generated interfaces)
+			for i, m := range t.allMethods {
+				if i > 0 {
+					buf.WriteString("; ")
+				}
+				buf.WriteString(m.name)
+				writeSignature(buf, m.typ.(*Signature), qf, visited)
+			}
+		} else {
+			// print explicit interface methods and embedded types
+			for i, m := range t.methods {
+				if i > 0 {
+					buf.WriteString("; ")
+				}
+				buf.WriteString(m.name)
+				writeSignature(buf, m.typ.(*Signature), qf, visited)
+			}
+			for i, typ := range t.embeddeds {
+				if i > 0 || len(t.methods) > 0 {
+					buf.WriteString("; ")
+				}
+				writeType(buf, typ, qf, visited)
+			}
+		}
+		buf.WriteByte('}')
+
+	case *Map:
+		buf.WriteString("map[")
+		writeType(buf, t.key, qf, visited)
+		buf.WriteByte(']')
+		writeType(buf, t.elem, qf, visited)
+
+	case *Chan:
+		var s string
+		var parens bool
+		switch t.dir {
+		case SendRecv:
+			s = "chan "
+			// chan (<-chan T) requires parentheses
+			if c, _ := t.elem.(*Chan); c != nil && c.dir == RecvOnly {
+				parens = true
+			}
+		case SendOnly:
+			s = "chan<- "
+		case RecvOnly:
+			s = "<-chan "
+		default:
+			panic("unreachable")
+		}
+		buf.WriteString(s)
+		if parens {
+			buf.WriteByte('(')
+		}
+		writeType(buf, t.elem, qf, visited)
+		if parens {
+			buf.WriteByte(')')
+		}
+
+	case *Named:
+		s := "<Named w/o object>"
+		if obj := t.obj; obj != nil {
+			if obj.pkg != nil {
+				writePackage(buf, obj.pkg, qf)
+			}
+			// TODO(gri): function-local named types should be displayed
+			// differently from named types at package level to avoid
+			// ambiguity.
+			s = obj.name
+		}
+		buf.WriteString(s)
+
+	default:
+		// For externally defined implementations of Type.
+		buf.WriteString(t.String())
+	}
+}
+
+func writeTuple(buf *bytes.Buffer, tup *Tuple, variadic bool, qf Qualifier, visited []Type) {
+	buf.WriteByte('(')
+	if tup != nil {
+		for i, v := range tup.vars {
+			if i > 0 {
+				buf.WriteString(", ")
+			}
+			if v.name != "" {
+				buf.WriteString(v.name)
+				buf.WriteByte(' ')
+			}
+			typ := v.typ
+			if variadic && i == len(tup.vars)-1 {
+				if s, ok := typ.(*Slice); ok {
+					buf.WriteString("...")
+					typ = s.elem
+				} else {
+					// special case:
+					// append(s, "foo"...) leads to signature func([]byte, string...)
+					if t, ok := typ.Underlying().(*Basic); !ok || t.kind != String {
+						panic("internal error: string type expected")
+					}
+					writeType(buf, typ, qf, visited)
+					buf.WriteString("...")
+					continue
+				}
+			}
+			writeType(buf, typ, qf, visited)
+		}
+	}
+	buf.WriteByte(')')
+}
+
+// WriteSignature writes the representation of the signature sig to buf,
+// without a leading "func" keyword.
+// The Qualifier controls the printing of
+// package-level objects, and may be nil.
+func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier) {
+	writeSignature(buf, sig, qf, make([]Type, 8))
+}
+
+func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
+	writeTuple(buf, sig.params, sig.variadic, qf, visited)
+
+	n := sig.results.Len()
+	if n == 0 {
+		// no result
+		return
+	}
+
+	buf.WriteByte(' ')
+	if n == 1 && sig.results.vars[0].name == "" {
+		// single unnamed result
+		writeType(buf, sig.results.vars[0].typ, qf, visited)
+		return
+	}
+
+	// multiple or named result(s)
+	writeTuple(buf, sig.results, false, qf, visited)
+}
diff --git a/libgo/go/go/types/typestring_test.go b/libgo/go/go/types/typestring_test.go
new file mode 100644
index 00000000000..913e6c735cc
--- /dev/null
+++ b/libgo/go/go/types/typestring_test.go
@@ -0,0 +1,168 @@
+// 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 types_test
+
+import (
+	"go/ast"
+	"go/importer"
+	"go/parser"
+	"go/token"
+	"internal/testenv"
+	"testing"
+
+	. "go/types"
+)
+
+const filename = "<src>"
+
+func makePkg(t *testing.T, src string) (*Package, error) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, filename, src, parser.DeclarationErrors)
+	if err != nil {
+		return nil, err
+	}
+	// use the package name as package path
+	conf := Config{Importer: importer.Default()}
+	return conf.Check(file.Name.Name, fset, []*ast.File{file}, nil)
+}
+
+type testEntry struct {
+	src, str string
+}
+
+// dup returns a testEntry where both src and str are the same.
+func dup(s string) testEntry {
+	return testEntry{s, s}
+}
+
+// types that don't depend on any other type declarations
+var independentTestTypes = []testEntry{
+	// basic types
+	dup("int"),
+	dup("float32"),
+	dup("string"),
+
+	// arrays
+	dup("[10]int"),
+
+	// slices
+	dup("[]int"),
+	dup("[][]int"),
+
+	// structs
+	dup("struct{}"),
+	dup("struct{x int}"),
+	{`struct {
+		x, y int
+		z float32 "foo"
+	}`, `struct{x int; y int; z float32 "foo"}`},
+	{`struct {
+		string
+		elems []complex128
+	}`, `struct{string; elems []complex128}`},
+
+	// pointers
+	dup("*int"),
+	dup("***struct{}"),
+	dup("*struct{a int; b float32}"),
+
+	// functions
+	dup("func()"),
+	dup("func(x int)"),
+	{"func(x, y int)", "func(x int, y int)"},
+	{"func(x, y int, z string)", "func(x int, y int, z string)"},
+	dup("func(int)"),
+	{"func(int, string, byte)", "func(int, string, byte)"},
+
+	dup("func() int"),
+	{"func() (string)", "func() string"},
+	dup("func() (u int)"),
+	{"func() (u, v int, w string)", "func() (u int, v int, w string)"},
+
+	dup("func(int) string"),
+	dup("func(x int) string"),
+	dup("func(x int) (u string)"),
+	{"func(x, y int) (u string)", "func(x int, y int) (u string)"},
+
+	dup("func(...int) string"),
+	dup("func(x ...int) string"),
+	dup("func(x ...int) (u string)"),
+	{"func(x, y ...int) (u string)", "func(x int, y ...int) (u string)"},
+
+	// interfaces
+	dup("interface{}"),
+	dup("interface{m()}"),
+	dup(`interface{String() string; m(int) float32}`),
+
+	// maps
+	dup("map[string]int"),
+	{"map[struct{x, y int}][]byte", "map[struct{x int; y int}][]byte"},
+
+	// channels
+	dup("chan<- chan int"),
+	dup("chan<- <-chan int"),
+	dup("<-chan <-chan int"),
+	dup("chan (<-chan int)"),
+	dup("chan<- func()"),
+	dup("<-chan []func() int"),
+}
+
+// types that depend on other type declarations (src in TestTypes)
+var dependentTestTypes = []testEntry{
+	// interfaces
+	dup(`interface{io.Reader; io.Writer}`),
+	dup(`interface{m() int; io.Writer}`),
+	{`interface{m() interface{T}}`, `interface{m() interface{p.T}}`},
+}
+
+func TestTypeString(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	var tests []testEntry
+	tests = append(tests, independentTestTypes...)
+	tests = append(tests, dependentTestTypes...)
+
+	for _, test := range tests {
+		src := `package p; import "io"; type _ io.Writer; type T ` + test.src
+		pkg, err := makePkg(t, src)
+		if err != nil {
+			t.Errorf("%s: %s", src, err)
+			continue
+		}
+		typ := pkg.Scope().Lookup("T").Type().Underlying()
+		if got := typ.String(); got != test.str {
+			t.Errorf("%s: got %s, want %s", test.src, got, test.str)
+		}
+	}
+}
+
+func TestQualifiedTypeString(t *testing.T) {
+	p, _ := pkgFor("p.go", "package p; type T int", nil)
+	q, _ := pkgFor("q.go", "package q", nil)
+
+	pT := p.Scope().Lookup("T").Type()
+	for _, test := range []struct {
+		typ  Type
+		this *Package
+		want string
+	}{
+		{pT, nil, "p.T"},
+		{pT, p, "T"},
+		{pT, q, "p.T"},
+		{NewPointer(pT), p, "*T"},
+		{NewPointer(pT), q, "*p.T"},
+	} {
+		qualifier := func(pkg *Package) string {
+			if pkg != test.this {
+				return pkg.Name()
+			}
+			return ""
+		}
+		if got := TypeString(test.typ, qualifier); got != test.want {
+			t.Errorf("TypeString(%s, %s) = %s, want %s",
+				test.this, test.typ, got, test.want)
+		}
+	}
+}
diff --git a/libgo/go/go/types/typexpr.go b/libgo/go/go/types/typexpr.go
new file mode 100644
index 00000000000..c744eeaa0c7
--- /dev/null
+++ b/libgo/go/go/types/typexpr.go
@@ -0,0 +1,712 @@
+// Copyright 2013 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.
+
+// This file implements type-checking of identifiers and type expressions.
+
+package types
+
+import (
+	"go/ast"
+	"go/constant"
+	"go/token"
+	"sort"
+	"strconv"
+)
+
+// ident type-checks identifier e and initializes x with the value or type of e.
+// If an error occurred, x.mode is set to invalid.
+// For the meaning of def and path, see check.typ, below.
+//
+func (check *Checker) ident(x *operand, e *ast.Ident, def *Named, path []*TypeName) {
+	x.mode = invalid
+	x.expr = e
+
+	scope, obj := check.scope.LookupParent(e.Name, check.pos)
+	if obj == nil {
+		if e.Name == "_" {
+			check.errorf(e.Pos(), "cannot use _ as value or type")
+		} else {
+			check.errorf(e.Pos(), "undeclared name: %s", e.Name)
+		}
+		return
+	}
+	check.recordUse(e, obj)
+
+	check.objDecl(obj, def, path)
+	typ := obj.Type()
+	assert(typ != nil)
+
+	// The object may be dot-imported: If so, remove its package from
+	// the map of unused dot imports for the respective file scope.
+	// (This code is only needed for dot-imports. Without them,
+	// we only have to mark variables, see *Var case below).
+	if pkg := obj.Pkg(); pkg != check.pkg && pkg != nil {
+		delete(check.unusedDotImports[scope], pkg)
+	}
+
+	switch obj := obj.(type) {
+	case *PkgName:
+		check.errorf(e.Pos(), "use of package %s not in selector", obj.name)
+		return
+
+	case *Const:
+		check.addDeclDep(obj)
+		if typ == Typ[Invalid] {
+			return
+		}
+		if obj == universeIota {
+			if check.iota == nil {
+				check.errorf(e.Pos(), "cannot use iota outside constant declaration")
+				return
+			}
+			x.val = check.iota
+		} else {
+			x.val = obj.val
+		}
+		assert(x.val != nil)
+		x.mode = constant_
+
+	case *TypeName:
+		x.mode = typexpr
+		// check for cycle
+		// (it's ok to iterate forward because each named type appears at most once in path)
+		for i, prev := range path {
+			if prev == obj {
+				check.errorf(obj.pos, "illegal cycle in declaration of %s", obj.name)
+				// print cycle
+				for _, obj := range path[i:] {
+					check.errorf(obj.Pos(), "\t%s refers to", obj.Name()) // secondary error, \t indented
+				}
+				check.errorf(obj.Pos(), "\t%s", obj.Name())
+				// maintain x.mode == typexpr despite error
+				typ = Typ[Invalid]
+				break
+			}
+		}
+
+	case *Var:
+		if obj.pkg == check.pkg {
+			obj.used = true
+		}
+		check.addDeclDep(obj)
+		if typ == Typ[Invalid] {
+			return
+		}
+		x.mode = variable
+
+	case *Func:
+		check.addDeclDep(obj)
+		x.mode = value
+
+	case *Builtin:
+		x.id = obj.id
+		x.mode = builtin
+
+	case *Nil:
+		x.mode = value
+
+	default:
+		unreachable()
+	}
+
+	x.typ = typ
+}
+
+// typExpr type-checks the type expression e and returns its type, or Typ[Invalid].
+// If def != nil, e is the type specification for the named type def, declared
+// in a type declaration, and def.underlying will be set to the type of e before
+// any components of e are type-checked. Path contains the path of named types
+// referring to this type.
+//
+func (check *Checker) typExpr(e ast.Expr, def *Named, path []*TypeName) (T Type) {
+	if trace {
+		check.trace(e.Pos(), "%s", e)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(e.Pos(), "=> %s", T)
+		}()
+	}
+
+	T = check.typExprInternal(e, def, path)
+	assert(isTyped(T))
+	check.recordTypeAndValue(e, typexpr, T, nil)
+
+	return
+}
+
+func (check *Checker) typ(e ast.Expr) Type {
+	return check.typExpr(e, nil, nil)
+}
+
+// funcType type-checks a function or method type.
+func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
+	scope := NewScope(check.scope, token.NoPos, token.NoPos, "function")
+	check.recordScope(ftyp, scope)
+
+	recvList, _ := check.collectParams(scope, recvPar, false)
+	params, variadic := check.collectParams(scope, ftyp.Params, true)
+	results, _ := check.collectParams(scope, ftyp.Results, false)
+
+	if recvPar != nil {
+		// recv parameter list present (may be empty)
+		// spec: "The receiver is specified via an extra parameter section preceding the
+		// method name. That parameter section must declare a single parameter, the receiver."
+		var recv *Var
+		switch len(recvList) {
+		case 0:
+			check.error(recvPar.Pos(), "method is missing receiver")
+			recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
+		default:
+			// more than one receiver
+			check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
+			fallthrough // continue with first receiver
+		case 1:
+			recv = recvList[0]
+		}
+		// spec: "The receiver type must be of the form T or *T where T is a type name."
+		// (ignore invalid types - error was reported before)
+		if t, _ := deref(recv.typ); t != Typ[Invalid] {
+			var err string
+			if T, _ := t.(*Named); T != nil {
+				// spec: "The type denoted by T is called the receiver base type; it must not
+				// be a pointer or interface type and it must be declared in the same package
+				// as the method."
+				if T.obj.pkg != check.pkg {
+					err = "type not defined in this package"
+				} else {
+					// TODO(gri) This is not correct if the underlying type is unknown yet.
+					switch u := T.underlying.(type) {
+					case *Basic:
+						// unsafe.Pointer is treated like a regular pointer
+						if u.kind == UnsafePointer {
+							err = "unsafe.Pointer"
+						}
+					case *Pointer, *Interface:
+						err = "pointer or interface type"
+					}
+				}
+			} else {
+				err = "basic or unnamed type"
+			}
+			if err != "" {
+				check.errorf(recv.pos, "invalid receiver %s (%s)", recv.typ, err)
+				// ok to continue
+			}
+		}
+		sig.recv = recv
+	}
+
+	sig.scope = scope
+	sig.params = NewTuple(params...)
+	sig.results = NewTuple(results...)
+	sig.variadic = variadic
+}
+
+// typExprInternal drives type checking of types.
+// Must only be called by typExpr.
+//
+func (check *Checker) typExprInternal(e ast.Expr, def *Named, path []*TypeName) Type {
+	switch e := e.(type) {
+	case *ast.BadExpr:
+		// ignore - error reported before
+
+	case *ast.Ident:
+		var x operand
+		check.ident(&x, e, def, path)
+
+		switch x.mode {
+		case typexpr:
+			typ := x.typ
+			def.setUnderlying(typ)
+			return typ
+		case invalid:
+			// ignore - error reported before
+		case novalue:
+			check.errorf(x.pos(), "%s used as type", &x)
+		default:
+			check.errorf(x.pos(), "%s is not a type", &x)
+		}
+
+	case *ast.SelectorExpr:
+		var x operand
+		check.selector(&x, e)
+
+		switch x.mode {
+		case typexpr:
+			typ := x.typ
+			def.setUnderlying(typ)
+			return typ
+		case invalid:
+			// ignore - error reported before
+		case novalue:
+			check.errorf(x.pos(), "%s used as type", &x)
+		default:
+			check.errorf(x.pos(), "%s is not a type", &x)
+		}
+
+	case *ast.ParenExpr:
+		return check.typExpr(e.X, def, path)
+
+	case *ast.ArrayType:
+		if e.Len != nil {
+			typ := new(Array)
+			def.setUnderlying(typ)
+			typ.len = check.arrayLength(e.Len)
+			typ.elem = check.typExpr(e.Elt, nil, path)
+			return typ
+
+		} else {
+			typ := new(Slice)
+			def.setUnderlying(typ)
+			typ.elem = check.typ(e.Elt)
+			return typ
+		}
+
+	case *ast.StructType:
+		typ := new(Struct)
+		def.setUnderlying(typ)
+		check.structType(typ, e, path)
+		return typ
+
+	case *ast.StarExpr:
+		typ := new(Pointer)
+		def.setUnderlying(typ)
+		typ.base = check.typ(e.X)
+		return typ
+
+	case *ast.FuncType:
+		typ := new(Signature)
+		def.setUnderlying(typ)
+		check.funcType(typ, nil, e)
+		return typ
+
+	case *ast.InterfaceType:
+		typ := new(Interface)
+		def.setUnderlying(typ)
+		check.interfaceType(typ, e, def, path)
+		return typ
+
+	case *ast.MapType:
+		typ := new(Map)
+		def.setUnderlying(typ)
+
+		typ.key = check.typ(e.Key)
+		typ.elem = check.typ(e.Value)
+
+		// spec: "The comparison operators == and != must be fully defined
+		// for operands of the key type; thus the key type must not be a
+		// function, map, or slice."
+		//
+		// Delay this check because it requires fully setup types;
+		// it is safe to continue in any case (was issue 6667).
+		check.delay(func() {
+			if !Comparable(typ.key) {
+				check.errorf(e.Key.Pos(), "invalid map key type %s", typ.key)
+			}
+		})
+
+		return typ
+
+	case *ast.ChanType:
+		typ := new(Chan)
+		def.setUnderlying(typ)
+
+		dir := SendRecv
+		switch e.Dir {
+		case ast.SEND | ast.RECV:
+			// nothing to do
+		case ast.SEND:
+			dir = SendOnly
+		case ast.RECV:
+			dir = RecvOnly
+		default:
+			check.invalidAST(e.Pos(), "unknown channel direction %d", e.Dir)
+			// ok to continue
+		}
+
+		typ.dir = dir
+		typ.elem = check.typ(e.Value)
+		return typ
+
+	default:
+		check.errorf(e.Pos(), "%s is not a type", e)
+	}
+
+	typ := Typ[Invalid]
+	def.setUnderlying(typ)
+	return typ
+}
+
+// typeOrNil type-checks the type expression (or nil value) e
+// and returns the typ of e, or nil.
+// If e is neither a type nor nil, typOrNil returns Typ[Invalid].
+//
+func (check *Checker) typOrNil(e ast.Expr) Type {
+	var x operand
+	check.rawExpr(&x, e, nil)
+	switch x.mode {
+	case invalid:
+		// ignore - error reported before
+	case novalue:
+		check.errorf(x.pos(), "%s used as type", &x)
+	case typexpr:
+		return x.typ
+	case value:
+		if x.isNil() {
+			return nil
+		}
+		fallthrough
+	default:
+		check.errorf(x.pos(), "%s is not a type", &x)
+	}
+	return Typ[Invalid]
+}
+
+func (check *Checker) arrayLength(e ast.Expr) int64 {
+	var x operand
+	check.expr(&x, e)
+	if x.mode != constant_ {
+		if x.mode != invalid {
+			check.errorf(x.pos(), "array length %s must be constant", &x)
+		}
+		return 0
+	}
+	if !x.isInteger() {
+		check.errorf(x.pos(), "array length %s must be integer", &x)
+		return 0
+	}
+	n, ok := constant.Int64Val(x.val)
+	if !ok || n < 0 {
+		check.errorf(x.pos(), "invalid array length %s", &x)
+		return 0
+	}
+	return n
+}
+
+func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, variadicOk bool) (params []*Var, variadic bool) {
+	if list == nil {
+		return
+	}
+
+	var named, anonymous bool
+	for i, field := range list.List {
+		ftype := field.Type
+		if t, _ := ftype.(*ast.Ellipsis); t != nil {
+			ftype = t.Elt
+			if variadicOk && i == len(list.List)-1 {
+				variadic = true
+			} else {
+				check.invalidAST(field.Pos(), "... not permitted")
+				// ignore ... and continue
+			}
+		}
+		typ := check.typ(ftype)
+		// The parser ensures that f.Tag is nil and we don't
+		// care if a constructed AST contains a non-nil tag.
+		if len(field.Names) > 0 {
+			// named parameter
+			for _, name := range field.Names {
+				if name.Name == "" {
+					check.invalidAST(name.Pos(), "anonymous parameter")
+					// ok to continue
+				}
+				par := NewParam(name.Pos(), check.pkg, name.Name, typ)
+				check.declare(scope, name, par, scope.pos)
+				params = append(params, par)
+			}
+			named = true
+		} else {
+			// anonymous parameter
+			par := NewParam(ftype.Pos(), check.pkg, "", typ)
+			check.recordImplicit(field, par)
+			params = append(params, par)
+			anonymous = true
+		}
+	}
+
+	if named && anonymous {
+		check.invalidAST(list.Pos(), "list contains both named and anonymous parameters")
+		// ok to continue
+	}
+
+	// For a variadic function, change the last parameter's type from T to []T.
+	if variadic && len(params) > 0 {
+		last := params[len(params)-1]
+		last.typ = &Slice{elem: last.typ}
+	}
+
+	return
+}
+
+func (check *Checker) declareInSet(oset *objset, pos token.Pos, obj Object) bool {
+	if alt := oset.insert(obj); alt != nil {
+		check.errorf(pos, "%s redeclared", obj.Name())
+		check.reportAltDecl(alt)
+		return false
+	}
+	return true
+}
+
+func (check *Checker) interfaceType(iface *Interface, ityp *ast.InterfaceType, def *Named, path []*TypeName) {
+	// empty interface: common case
+	if ityp.Methods == nil {
+		return
+	}
+
+	// The parser ensures that field tags are nil and we don't
+	// care if a constructed AST contains non-nil tags.
+
+	// use named receiver type if available (for better error messages)
+	var recvTyp Type = iface
+	if def != nil {
+		recvTyp = def
+	}
+
+	// Phase 1: Collect explicitly declared methods, the corresponding
+	//          signature (AST) expressions, and the list of embedded
+	//          type (AST) expressions. Do not resolve signatures or
+	//          embedded types yet to avoid cycles referring to this
+	//          interface.
+
+	var (
+		mset       objset
+		signatures []ast.Expr // list of corresponding method signatures
+		embedded   []ast.Expr // list of embedded types
+	)
+	for _, f := range ityp.Methods.List {
+		if len(f.Names) > 0 {
+			// The parser ensures that there's only one method
+			// and we don't care if a constructed AST has more.
+			name := f.Names[0]
+			pos := name.Pos()
+			// spec: "As with all method sets, in an interface type,
+			// each method must have a unique non-blank name."
+			if name.Name == "_" {
+				check.errorf(pos, "invalid method name _")
+				continue
+			}
+			// Don't type-check signature yet - use an
+			// empty signature now and update it later.
+			// Since we know the receiver, set it up now
+			// (required to avoid crash in ptrRecv; see
+			// e.g. test case for issue 6638).
+			// TODO(gri) Consider marking methods signatures
+			// as incomplete, for better error messages. See
+			// also the T4 and T5 tests in testdata/cycles2.src.
+			sig := new(Signature)
+			sig.recv = NewVar(pos, check.pkg, "", recvTyp)
+			m := NewFunc(pos, check.pkg, name.Name, sig)
+			if check.declareInSet(&mset, pos, m) {
+				iface.methods = append(iface.methods, m)
+				iface.allMethods = append(iface.allMethods, m)
+				signatures = append(signatures, f.Type)
+				check.recordDef(name, m)
+			}
+		} else {
+			// embedded type
+			embedded = append(embedded, f.Type)
+		}
+	}
+
+	// Phase 2: Resolve embedded interfaces. Because an interface must not
+	//          embed itself (directly or indirectly), each embedded interface
+	//          can be fully resolved without depending on any method of this
+	//          interface (if there is a cycle or another error, the embedded
+	//          type resolves to an invalid type and is ignored).
+	//          In particular, the list of methods for each embedded interface
+	//          must be complete (it cannot depend on this interface), and so
+	//          those methods can be added to the list of all methods of this
+	//          interface.
+
+	for _, e := range embedded {
+		pos := e.Pos()
+		typ := check.typExpr(e, nil, path)
+		// Determine underlying embedded (possibly incomplete) type
+		// by following its forward chain.
+		named, _ := typ.(*Named)
+		under := underlying(named)
+		embed, _ := under.(*Interface)
+		if embed == nil {
+			if typ != Typ[Invalid] {
+				check.errorf(pos, "%s is not an interface", typ)
+			}
+			continue
+		}
+		iface.embeddeds = append(iface.embeddeds, named)
+		// collect embedded methods
+		for _, m := range embed.allMethods {
+			if check.declareInSet(&mset, pos, m) {
+				iface.allMethods = append(iface.allMethods, m)
+			}
+		}
+	}
+
+	// Phase 3: At this point all methods have been collected for this interface.
+	//          It is now safe to type-check the signatures of all explicitly
+	//          declared methods, even if they refer to this interface via a cycle
+	//          and embed the methods of this interface in a parameter of interface
+	//          type.
+
+	for i, m := range iface.methods {
+		expr := signatures[i]
+		typ := check.typ(expr)
+		sig, _ := typ.(*Signature)
+		if sig == nil {
+			if typ != Typ[Invalid] {
+				check.invalidAST(expr.Pos(), "%s is not a method signature", typ)
+			}
+			continue // keep method with empty method signature
+		}
+		// update signature, but keep recv that was set up before
+		old := m.typ.(*Signature)
+		sig.recv = old.recv
+		*old = *sig // update signature (don't replace it!)
+	}
+
+	// TODO(gri) The list of explicit methods is only sorted for now to
+	// produce the same Interface as NewInterface. We may be able to
+	// claim source order in the future. Revisit.
+	sort.Sort(byUniqueMethodName(iface.methods))
+
+	// TODO(gri) The list of embedded types is only sorted for now to
+	// produce the same Interface as NewInterface. We may be able to
+	// claim source order in the future. Revisit.
+	sort.Sort(byUniqueTypeName(iface.embeddeds))
+
+	sort.Sort(byUniqueMethodName(iface.allMethods))
+}
+
+// byUniqueTypeName named type lists can be sorted by their unique type names.
+type byUniqueTypeName []*Named
+
+func (a byUniqueTypeName) Len() int           { return len(a) }
+func (a byUniqueTypeName) Less(i, j int) bool { return a[i].obj.Id() < a[j].obj.Id() }
+func (a byUniqueTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+// byUniqueMethodName method lists can be sorted by their unique method names.
+type byUniqueMethodName []*Func
+
+func (a byUniqueMethodName) Len() int           { return len(a) }
+func (a byUniqueMethodName) Less(i, j int) bool { return a[i].Id() < a[j].Id() }
+func (a byUniqueMethodName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+func (check *Checker) tag(t *ast.BasicLit) string {
+	if t != nil {
+		if t.Kind == token.STRING {
+			if val, err := strconv.Unquote(t.Value); err == nil {
+				return val
+			}
+		}
+		check.invalidAST(t.Pos(), "incorrect tag syntax: %q", t.Value)
+	}
+	return ""
+}
+
+func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeName) {
+	list := e.Fields
+	if list == nil {
+		return
+	}
+
+	// struct fields and tags
+	var fields []*Var
+	var tags []string
+
+	// for double-declaration checks
+	var fset objset
+
+	// current field typ and tag
+	var typ Type
+	var tag string
+	// anonymous != nil indicates an anonymous field.
+	add := func(field *ast.Field, ident *ast.Ident, anonymous *TypeName, pos token.Pos) {
+		if tag != "" && tags == nil {
+			tags = make([]string, len(fields))
+		}
+		if tags != nil {
+			tags = append(tags, tag)
+		}
+
+		name := ident.Name
+		fld := NewField(pos, check.pkg, name, typ, anonymous != nil)
+		// spec: "Within a struct, non-blank field names must be unique."
+		if name == "_" || check.declareInSet(&fset, pos, fld) {
+			fields = append(fields, fld)
+			check.recordDef(ident, fld)
+		}
+		if anonymous != nil {
+			check.recordUse(ident, anonymous)
+		}
+	}
+
+	for _, f := range list.List {
+		typ = check.typExpr(f.Type, nil, path)
+		tag = check.tag(f.Tag)
+		if len(f.Names) > 0 {
+			// named fields
+			for _, name := range f.Names {
+				add(f, name, nil, name.Pos())
+			}
+		} else {
+			// anonymous field
+			name := anonymousFieldIdent(f.Type)
+			pos := f.Type.Pos()
+			t, isPtr := deref(typ)
+			switch t := t.(type) {
+			case *Basic:
+				if t == Typ[Invalid] {
+					// error was reported before
+					continue
+				}
+				// unsafe.Pointer is treated like a regular pointer
+				if t.kind == UnsafePointer {
+					check.errorf(pos, "anonymous field type cannot be unsafe.Pointer")
+					continue
+				}
+				add(f, name, Universe.Lookup(t.name).(*TypeName), pos)
+
+			case *Named:
+				// spec: "An embedded type must be specified as a type name
+				// T or as a pointer to a non-interface type name *T, and T
+				// itself may not be a pointer type."
+				switch u := t.underlying.(type) {
+				case *Basic:
+					// unsafe.Pointer is treated like a regular pointer
+					if u.kind == UnsafePointer {
+						check.errorf(pos, "anonymous field type cannot be unsafe.Pointer")
+						continue
+					}
+				case *Pointer:
+					check.errorf(pos, "anonymous field type cannot be a pointer")
+					continue
+				case *Interface:
+					if isPtr {
+						check.errorf(pos, "anonymous field type cannot be a pointer to an interface")
+						continue
+					}
+				}
+				add(f, name, t.obj, pos)
+
+			default:
+				check.invalidAST(pos, "anonymous field type %s must be named", typ)
+			}
+		}
+	}
+
+	styp.fields = fields
+	styp.tags = tags
+}
+
+func anonymousFieldIdent(e ast.Expr) *ast.Ident {
+	switch e := e.(type) {
+	case *ast.Ident:
+		return e
+	case *ast.StarExpr:
+		return anonymousFieldIdent(e.X)
+	case *ast.SelectorExpr:
+		return e.Sel
+	}
+	return nil // invalid anonymous field
+}
diff --git a/libgo/go/go/types/universe.go b/libgo/go/go/types/universe.go
new file mode 100644
index 00000000000..40185c1ad42
--- /dev/null
+++ b/libgo/go/go/types/universe.go
@@ -0,0 +1,223 @@
+// 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.
+
+// This file sets up the universe scope and the unsafe package.
+
+package types
+
+import (
+	"go/constant"
+	"go/token"
+	"strings"
+)
+
+var (
+	Universe     *Scope
+	Unsafe       *Package
+	universeIota *Const
+	universeByte *Basic // uint8 alias, but has name "byte"
+	universeRune *Basic // int32 alias, but has name "rune"
+)
+
+var Typ = []*Basic{
+	Invalid: {Invalid, 0, "invalid type"},
+
+	Bool:          {Bool, IsBoolean, "bool"},
+	Int:           {Int, IsInteger, "int"},
+	Int8:          {Int8, IsInteger, "int8"},
+	Int16:         {Int16, IsInteger, "int16"},
+	Int32:         {Int32, IsInteger, "int32"},
+	Int64:         {Int64, IsInteger, "int64"},
+	Uint:          {Uint, IsInteger | IsUnsigned, "uint"},
+	Uint8:         {Uint8, IsInteger | IsUnsigned, "uint8"},
+	Uint16:        {Uint16, IsInteger | IsUnsigned, "uint16"},
+	Uint32:        {Uint32, IsInteger | IsUnsigned, "uint32"},
+	Uint64:        {Uint64, IsInteger | IsUnsigned, "uint64"},
+	Uintptr:       {Uintptr, IsInteger | IsUnsigned, "uintptr"},
+	Float32:       {Float32, IsFloat, "float32"},
+	Float64:       {Float64, IsFloat, "float64"},
+	Complex64:     {Complex64, IsComplex, "complex64"},
+	Complex128:    {Complex128, IsComplex, "complex128"},
+	String:        {String, IsString, "string"},
+	UnsafePointer: {UnsafePointer, 0, "Pointer"},
+
+	UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
+	UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},
+	UntypedRune:    {UntypedRune, IsInteger | IsUntyped, "untyped rune"},
+	UntypedFloat:   {UntypedFloat, IsFloat | IsUntyped, "untyped float"},
+	UntypedComplex: {UntypedComplex, IsComplex | IsUntyped, "untyped complex"},
+	UntypedString:  {UntypedString, IsString | IsUntyped, "untyped string"},
+	UntypedNil:     {UntypedNil, IsUntyped, "untyped nil"},
+}
+
+var aliases = [...]*Basic{
+	{Byte, IsInteger | IsUnsigned, "byte"},
+	{Rune, IsInteger, "rune"},
+}
+
+func defPredeclaredTypes() {
+	for _, t := range Typ {
+		def(NewTypeName(token.NoPos, nil, t.name, t))
+	}
+	for _, t := range aliases {
+		def(NewTypeName(token.NoPos, nil, t.name, t))
+	}
+
+	// Error has a nil package in its qualified name since it is in no package
+	res := NewVar(token.NoPos, nil, "", Typ[String])
+	sig := &Signature{results: NewTuple(res)}
+	err := NewFunc(token.NoPos, nil, "Error", sig)
+	typ := &Named{underlying: NewInterface([]*Func{err}, nil).Complete()}
+	sig.recv = NewVar(token.NoPos, nil, "", typ)
+	def(NewTypeName(token.NoPos, nil, "error", typ))
+}
+
+var predeclaredConsts = [...]struct {
+	name string
+	kind BasicKind
+	val  constant.Value
+}{
+	{"true", UntypedBool, constant.MakeBool(true)},
+	{"false", UntypedBool, constant.MakeBool(false)},
+	{"iota", UntypedInt, constant.MakeInt64(0)},
+}
+
+func defPredeclaredConsts() {
+	for _, c := range predeclaredConsts {
+		def(NewConst(token.NoPos, nil, c.name, Typ[c.kind], c.val))
+	}
+}
+
+func defPredeclaredNil() {
+	def(&Nil{object{name: "nil", typ: Typ[UntypedNil]}})
+}
+
+// A builtinId is the id of a builtin function.
+type builtinId int
+
+const (
+	// universe scope
+	_Append builtinId = iota
+	_Cap
+	_Close
+	_Complex
+	_Copy
+	_Delete
+	_Imag
+	_Len
+	_Make
+	_New
+	_Panic
+	_Print
+	_Println
+	_Real
+	_Recover
+
+	// package unsafe
+	_Alignof
+	_Offsetof
+	_Sizeof
+
+	// testing support
+	_Assert
+	_Trace
+)
+
+var predeclaredFuncs = [...]struct {
+	name     string
+	nargs    int
+	variadic bool
+	kind     exprKind
+}{
+	_Append:  {"append", 1, true, expression},
+	_Cap:     {"cap", 1, false, expression},
+	_Close:   {"close", 1, false, statement},
+	_Complex: {"complex", 2, false, expression},
+	_Copy:    {"copy", 2, false, statement},
+	_Delete:  {"delete", 2, false, statement},
+	_Imag:    {"imag", 1, false, expression},
+	_Len:     {"len", 1, false, expression},
+	_Make:    {"make", 1, true, expression},
+	_New:     {"new", 1, false, expression},
+	_Panic:   {"panic", 1, false, statement},
+	_Print:   {"print", 0, true, statement},
+	_Println: {"println", 0, true, statement},
+	_Real:    {"real", 1, false, expression},
+	_Recover: {"recover", 0, false, statement},
+
+	_Alignof:  {"Alignof", 1, false, expression},
+	_Offsetof: {"Offsetof", 1, false, expression},
+	_Sizeof:   {"Sizeof", 1, false, expression},
+
+	_Assert: {"assert", 1, false, statement},
+	_Trace:  {"trace", 0, true, statement},
+}
+
+func defPredeclaredFuncs() {
+	for i := range predeclaredFuncs {
+		id := builtinId(i)
+		if id == _Assert || id == _Trace {
+			continue // only define these in testing environment
+		}
+		def(newBuiltin(id))
+	}
+}
+
+// DefPredeclaredTestFuncs defines the assert and trace built-ins.
+// These built-ins are intended for debugging and testing of this
+// package only.
+func DefPredeclaredTestFuncs() {
+	if Universe.Lookup("assert") != nil {
+		return // already defined
+	}
+	def(newBuiltin(_Assert))
+	def(newBuiltin(_Trace))
+}
+
+func init() {
+	Universe = NewScope(nil, token.NoPos, token.NoPos, "universe")
+	Unsafe = NewPackage("unsafe", "unsafe")
+	Unsafe.complete = true
+
+	defPredeclaredTypes()
+	defPredeclaredConsts()
+	defPredeclaredNil()
+	defPredeclaredFuncs()
+
+	universeIota = Universe.Lookup("iota").(*Const)
+	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
+	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
+}
+
+// Objects with names containing blanks are internal and not entered into
+// a scope. Objects with exported names are inserted in the unsafe package
+// scope; other objects are inserted in the universe scope.
+//
+func def(obj Object) {
+	name := obj.Name()
+	if strings.Index(name, " ") >= 0 {
+		return // nothing to do
+	}
+	// fix Obj link for named types
+	if typ, ok := obj.Type().(*Named); ok {
+		typ.obj = obj.(*TypeName)
+	}
+	// exported identifiers go into package unsafe
+	scope := Universe
+	if obj.Exported() {
+		scope = Unsafe.scope
+		// set Pkg field
+		switch obj := obj.(type) {
+		case *TypeName:
+			obj.pkg = Unsafe
+		case *Builtin:
+			obj.pkg = Unsafe
+		default:
+			unreachable()
+		}
+	}
+	if scope.Insert(obj) != nil {
+		panic("internal error: double declaration")
+	}
+}