Adding upstream version 1.17.13.upstream/1.17.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

67 files changed, 5207 insertions, 0 deletions

diff --git a/src/go/internal/gccgoimporter/ar.go b/src/go/internal/gccgoimporter/ar.go
new file mode 100644
index 0000000..443aa26
--- /dev/null
+++ b/src/go/internal/gccgoimporter/ar.go
@@ -0,0 +1,171 @@
+// Copyright 2018 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"
+	"debug/elf"
+	"errors"
+	"fmt"
+	"internal/xcoff"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// Magic strings for different archive file formats.
+const (
+	armag  = "!<arch>\n"
+	armagt = "!<thin>\n"
+	armagb = "<bigaf>\n"
+)
+
+// Offsets and sizes for fields in a standard archive header.
+const (
+	arNameOff  = 0
+	arNameSize = 16
+	arDateOff  = arNameOff + arNameSize
+	arDateSize = 12
+	arUIDOff   = arDateOff + arDateSize
+	arUIDSize  = 6
+	arGIDOff   = arUIDOff + arUIDSize
+	arGIDSize  = 6
+	arModeOff  = arGIDOff + arGIDSize
+	arModeSize = 8
+	arSizeOff  = arModeOff + arModeSize
+	arSizeSize = 10
+	arFmagOff  = arSizeOff + arSizeSize
+	arFmagSize = 2
+
+	arHdrSize = arFmagOff + arFmagSize
+)
+
+// The contents of the fmag field of a standard archive header.
+const arfmag = "`\n"
+
+// arExportData takes an archive file and returns a ReadSeeker for the
+// export data in that file. This assumes that there is only one
+// object in the archive containing export data, which is not quite
+// what gccgo does; gccgo concatenates together all the export data
+// for all the objects in the file.  In practice that case does not arise.
+func arExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
+	if _, err := archive.Seek(0, io.SeekStart); err != nil {
+		return nil, err
+	}
+
+	var buf [len(armag)]byte
+	if _, err := archive.Read(buf[:]); err != nil {
+		return nil, err
+	}
+
+	switch string(buf[:]) {
+	case armag:
+		return standardArExportData(archive)
+	case armagt:
+		return nil, errors.New("unsupported thin archive")
+	case armagb:
+		return aixBigArExportData(archive)
+	default:
+		return nil, fmt.Errorf("unrecognized archive file format %q", buf[:])
+	}
+}
+
+// standardArExportData returns export data from a standard archive.
+func standardArExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
+	off := int64(len(armag))
+	for {
+		var hdrBuf [arHdrSize]byte
+		if _, err := archive.Read(hdrBuf[:]); err != nil {
+			return nil, err
+		}
+		off += arHdrSize
+
+		if bytes.Compare(hdrBuf[arFmagOff:arFmagOff+arFmagSize], []byte(arfmag)) != 0 {
+			return nil, fmt.Errorf("archive header format header (%q)", hdrBuf[:])
+		}
+
+		size, err := strconv.ParseInt(strings.TrimSpace(string(hdrBuf[arSizeOff:arSizeOff+arSizeSize])), 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing size in archive header (%q): %v", hdrBuf[:], err)
+		}
+
+		fn := hdrBuf[arNameOff : arNameOff+arNameSize]
+		if fn[0] == '/' && (fn[1] == ' ' || fn[1] == '/' || bytes.Compare(fn[:8], []byte("/SYM64/ ")) == 0) {
+			// Archive symbol table or extended name table,
+			// which we don't care about.
+		} else {
+			archiveAt := readerAtFromSeeker(archive)
+			ret, err := elfFromAr(io.NewSectionReader(archiveAt, off, size))
+			if ret != nil || err != nil {
+				return ret, err
+			}
+		}
+
+		if size&1 != 0 {
+			size++
+		}
+		off += size
+		if _, err := archive.Seek(off, io.SeekStart); err != nil {
+			return nil, err
+		}
+	}
+}
+
+// elfFromAr tries to get export data from an archive member as an ELF file.
+// If there is no export data, this returns nil, nil.
+func elfFromAr(member *io.SectionReader) (io.ReadSeeker, error) {
+	ef, err := elf.NewFile(member)
+	if err != nil {
+		return nil, err
+	}
+	sec := ef.Section(".go_export")
+	if sec == nil {
+		return nil, nil
+	}
+	return sec.Open(), nil
+}
+
+// aixBigArExportData returns export data from an AIX big archive.
+func aixBigArExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
+	archiveAt := readerAtFromSeeker(archive)
+	arch, err := xcoff.NewArchive(archiveAt)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, mem := range arch.Members {
+		f, err := arch.GetFile(mem.Name)
+		if err != nil {
+			return nil, err
+		}
+		sdat := f.CSect(".go_export")
+		if sdat != nil {
+			return bytes.NewReader(sdat), nil
+		}
+	}
+
+	return nil, fmt.Errorf(".go_export not found in this archive")
+}
+
+// readerAtFromSeeker turns an io.ReadSeeker into an io.ReaderAt.
+// This is only safe because there won't be any concurrent seeks
+// while this code is executing.
+func readerAtFromSeeker(rs io.ReadSeeker) io.ReaderAt {
+	if ret, ok := rs.(io.ReaderAt); ok {
+		return ret
+	}
+	return seekerReadAt{rs}
+}
+
+type seekerReadAt struct {
+	seeker io.ReadSeeker
+}
+
+func (sra seekerReadAt) ReadAt(p []byte, off int64) (int, error) {
+	if _, err := sra.seeker.Seek(off, io.SeekStart); err != nil {
+		return 0, err
+	}
+	return sra.seeker.Read(p)
+}
diff --git a/src/go/internal/gccgoimporter/gccgoinstallation.go b/src/go/internal/gccgoimporter/gccgoinstallation.go
new file mode 100644
index 0000000..e90a3cc
--- /dev/null
+++ b/src/go/internal/gccgoimporter/gccgoinstallation.go
@@ -0,0 +1,97 @@
+// 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"
+	exec "internal/execabs"
+	"os"
+	"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.
+// The given arguments are passed directly to the call of the driver.
+func (inst *GccgoInstallation) InitFromDriver(gccgoPath string, args ...string) (err error) {
+	argv := append([]string{"-###", "-S", "-x", "go", "-"}, args...)
+	cmd := exec.Command(gccgoPath, argv...)
+	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:])
+				}
+			}
+		}
+	}
+
+	argv = append([]string{"-dumpversion"}, args...)
+	stdout, err := exec.Command(gccgoPath, argv...).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/src/go/internal/gccgoimporter/gccgoinstallation_test.go b/src/go/internal/gccgoimporter/gccgoinstallation_test.go
new file mode 100644
index 0000000..df0188a
--- /dev/null
+++ b/src/go/internal/gccgoimporter/gccgoinstallation_test.go
@@ -0,0 +1,192 @@
+// 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"
+	"testing"
+)
+
+// importablePackages is a list of packages that we verify that we can
+// import. This should be all standard library packages in all relevant
+// versions of gccgo. Note that since gccgo follows a different release
+// cycle, and since different systems have different versions installed,
+// we can't use the last-two-versions rule of the gc toolchain.
+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", // Added in GCC 4.9.
+	"encoding/hex",
+	"encoding/json",
+	"encoding/pem",
+	"encoding/xml",
+	"errors",
+	"expvar",
+	"flag",
+	"fmt",
+	"go/ast",
+	"go/build",
+	"go/doc",
+	// "go/format", // Added in GCC 4.8.
+	"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", // Added in GCC 4.9.
+	"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", // Added in GCC 4.8.
+	"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",
+	"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.
+	gpath := gccgoPath()
+	if gpath == "" {
+		t.Skip("This test needs gccgo")
+	}
+
+	var inst GccgoInstallation
+	err := inst.InitFromDriver(gpath)
+	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, ".", nil)
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	for _, pkg := range importablePackages {
+		_, err = imp(make(map[string]*types.Package), pkg, ".", nil)
+		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 []byte) (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: "Search", want: "func Search(n int, f func(int) bool) int"},
+		{pkgpath: "unsafe", name: "Pointer", want: "type Pointer"},
+	} {
+		runImporterTest(t, imp, nil, &test)
+	}
+}
diff --git a/src/go/internal/gccgoimporter/importer.go b/src/go/internal/gccgoimporter/importer.go
new file mode 100644
index 0000000..94f2def
--- /dev/null
+++ b/src/go/internal/gccgoimporter/importer.go
@@ -0,0 +1,261 @@
+// 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"
+	"internal/xcoff"
+	"io"
+	"os"
+	"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"
+	gccgov2Magic    = "v2;\n"
+	gccgov3Magic    = "v3;\n"
+	goimporterMagic = "\n$$ "
+	archiveMagic    = "!<ar"
+	aixbigafMagic   = "<big"
+)
+
+// 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
+	}
+
+	var objreader io.ReaderAt
+	switch string(magic[:]) {
+	case gccgov1Magic, gccgov2Magic, gccgov3Magic, goimporterMagic:
+		// Raw export data.
+		reader = f
+		return
+
+	case archiveMagic, aixbigafMagic:
+		reader, err = arExportData(f)
+		return
+
+	default:
+		objreader = f
+	}
+
+	ef, err := elf.NewFile(objreader)
+	if err == nil {
+		sec := ef.Section(".go_export")
+		if sec == nil {
+			err = fmt.Errorf("%s: .go_export section not found", fpath)
+			return
+		}
+		reader = sec.Open()
+		return
+	}
+
+	xf, err := xcoff.NewFile(objreader)
+	if err == nil {
+		sdat := xf.CSect(".go_export")
+		if sdat == nil {
+			err = fmt.Errorf("%s: .go_export section not found", fpath)
+			return
+		}
+		reader = bytes.NewReader(sdat)
+		return
+	}
+
+	err = fmt.Errorf("%s: unrecognized file format", fpath)
+	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, srcDir string, lookup func(string) (io.ReadCloser, error)) (*types.Package, error)
+
+func GetImporter(searchpaths []string, initmap map[*types.Package]InitData) Importer {
+	return func(imports map[string]*types.Package, pkgpath, srcDir string, lookup func(string) (io.ReadCloser, error)) (pkg *types.Package, err error) {
+		// TODO(gri): Use srcDir.
+		// Or not. It's possible that srcDir will fade in importance as
+		// the go command and other tools provide a translation table
+		// for relative imports (like ./foo or vendored imports).
+		if pkgpath == "unsafe" {
+			return types.Unsafe, nil
+		}
+
+		var reader io.ReadSeeker
+		var fpath string
+		var rc io.ReadCloser
+		if lookup != nil {
+			if p := imports[pkgpath]; p != nil && p.Complete() {
+				return p, nil
+			}
+			rc, err = lookup(pkgpath)
+			if err != nil {
+				return nil, err
+			}
+		}
+		if rc != nil {
+			defer rc.Close()
+			rs, ok := rc.(io.ReadSeeker)
+			if !ok {
+				return nil, fmt.Errorf("gccgo importer requires lookup to return an io.ReadSeeker, have %T", rc)
+			}
+			reader = rs
+			fpath = "<lookup " + pkgpath + ">"
+			// Take name from Name method (like on os.File) if present.
+			if n, ok := rc.(interface{ Name() string }); ok {
+				fpath = n.Name()
+			}
+		} else {
+			fpath, err = findExportFile(searchpaths, pkgpath)
+			if err != nil {
+				return nil, err
+			}
+
+			r, closer, err := openExportFile(fpath)
+			if err != nil {
+				return nil, err
+			}
+			if closer != nil {
+				defer closer.Close()
+			}
+			reader = r
+		}
+
+		var magics string
+		magics, err = readMagic(reader)
+		if err != nil {
+			return
+		}
+
+		if magics == archiveMagic || magics == aixbigafMagic {
+			reader, err = arExportData(reader)
+			if err != nil {
+				return
+			}
+			magics, err = readMagic(reader)
+			if err != nil {
+				return
+			}
+		}
+
+		switch magics {
+		case gccgov1Magic, gccgov2Magic, gccgov3Magic:
+			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 = io.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", magics)
+		}
+
+		return
+	}
+}
+
+// readMagic reads the four bytes at the start of a ReadSeeker and
+// returns them as a string.
+func readMagic(reader io.ReadSeeker) (string, error) {
+	var magic [4]byte
+	if _, err := reader.Read(magic[:]); err != nil {
+		return "", err
+	}
+	if _, err := reader.Seek(0, io.SeekStart); err != nil {
+		return "", err
+	}
+	return string(magic[:]), nil
+}
diff --git a/src/go/internal/gccgoimporter/importer_test.go b/src/go/internal/gccgoimporter/importer_test.go
new file mode 100644
index 0000000..8a7ee1a
--- /dev/null
+++ b/src/go/internal/gccgoimporter/importer_test.go
@@ -0,0 +1,199 @@
+// 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"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"testing"
+)
+
+type importerTest struct {
+	pkgpath, name, want, wantval string
+	wantinits                    []string
+	gccgoVersion                 int // minimum gccgo version (0 => any)
+}
+
+func runImporterTest(t *testing.T, imp Importer, initmap map[*types.Package]InitData, test *importerTest) {
+	pkg, err := imp(make(map[string]*types.Package), test.pkgpath, ".", nil)
+	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] {
+				found = true
+				break
+			}
+		}
+
+		if !found {
+			t.Errorf("%s: could not find expected function %q", test.pkgpath, test.wantinits[0])
+		}
+
+		// FIXME: the original version of this test was written against
+		// the v1 export data scheme for capturing init functions, so it
+		// verified the priority values. We moved away from the priority
+		// scheme some time ago; it is not clear how much work it would be
+		// to validate the new init export data.
+	}
+}
+
+// When adding tests to this list, be sure to set the 'gccgoVersion'
+// field if the testcases uses a "recent" Go addition (ex: aliases).
+var importerTests = [...]importerTest{
+	{pkgpath: "pointer", name: "Int8Ptr", want: "type Int8Ptr *int8"},
+	{pkgpath: "complexnums", name: "NN", want: "const NN untyped complex", wantval: "(-1 + -1i)"},
+	{pkgpath: "complexnums", name: "NP", want: "const NP untyped complex", wantval: "(-1 + 1i)"},
+	{pkgpath: "complexnums", name: "PN", want: "const PN untyped complex", wantval: "(1 + -1i)"},
+	{pkgpath: "complexnums", name: "PP", want: "const PP untyped complex", wantval: "(1 + 1i)"},
+	{pkgpath: "conversions", name: "Bits", want: "const Bits Units", wantval: `"bits"`},
+	{pkgpath: "time", name: "Duration", want: "type Duration int64"},
+	{pkgpath: "time", name: "Nanosecond", want: "const Nanosecond Duration", wantval: "1"},
+	{pkgpath: "unicode", name: "IsUpper", want: "func IsUpper(r rune) bool"},
+	{pkgpath: "unicode", name: "MaxRune", want: "const MaxRune untyped rune", wantval: "1114111"},
+	{pkgpath: "imports", wantinits: []string{"imports..import", "fmt..import"}},
+	{pkgpath: "importsar", name: "Hello", want: "var Hello string"},
+	{pkgpath: "aliases", name: "A14", gccgoVersion: 7, want: "type A14 = func(int, T0) chan T2"},
+	{pkgpath: "aliases", name: "C0", gccgoVersion: 7, want: "type C0 struct{f1 C1; f2 C1}"},
+	{pkgpath: "escapeinfo", name: "NewT", want: "func NewT(data []byte) *T"},
+	{pkgpath: "issue27856", name: "M", gccgoVersion: 7, want: "type M struct{E F}"},
+	{pkgpath: "v1reflect", name: "Type", want: "type Type interface{Align() int; AssignableTo(u Type) bool; Bits() int; ChanDir() ChanDir; Elem() Type; Field(i int) StructField; FieldAlign() int; FieldByIndex(index []int) StructField; FieldByName(name string) (StructField, bool); FieldByNameFunc(match func(string) bool) (StructField, bool); Implements(u Type) bool; In(i int) Type; IsVariadic() bool; Key() Type; Kind() Kind; Len() int; Method(int) Method; MethodByName(string) (Method, bool); Name() string; NumField() int; NumIn() int; NumMethod() int; NumOut() int; Out(i int) Type; PkgPath() string; Size() uintptr; String() string; common() *commonType; rawString() string; runtimeType() *runtimeType; uncommon() *uncommonType}"},
+	{pkgpath: "nointerface", name: "I", want: "type I int"},
+	{pkgpath: "issue29198", name: "FooServer", gccgoVersion: 7, want: "type FooServer struct{FooServer *FooServer; user string; ctx context.Context}"},
+	{pkgpath: "issue30628", name: "Apple", want: "type Apple struct{hey sync.RWMutex; x int; RQ [517]struct{Count uintptr; NumBytes uintptr; Last uintptr}}"},
+	{pkgpath: "issue31540", name: "S", gccgoVersion: 7, want: "type S struct{b int; map[Y]Z}"}, // should want "type S struct{b int; A2}" (issue  #44410)
+	{pkgpath: "issue34182", name: "T1", want: "type T1 struct{f *T2}"},
+	{pkgpath: "notinheap", name: "S", want: "type S struct{}"},
+}
+
+func TestGoxImporter(t *testing.T) {
+	testenv.MustHaveExec(t)
+	initmap := make(map[*types.Package]InitData)
+	imp := GetImporter([]string{"testdata"}, initmap)
+
+	for _, test := range importerTests {
+		runImporterTest(t, imp, initmap, &test)
+	}
+}
+
+// gccgoPath returns a path to gccgo if it is present (either in
+// path or specified via GCCGO environment variable), or an
+// empty string if no gccgo is available.
+func gccgoPath() string {
+	gccgoname := os.Getenv("GCCGO")
+	if gccgoname == "" {
+		gccgoname = "gccgo"
+	}
+	if gpath, gerr := exec.LookPath(gccgoname); gerr == nil {
+		return gpath
+	}
+	return ""
+}
+
+func TestObjImporter(t *testing.T) {
+	// This test relies on gccgo being around.
+	gpath := gccgoPath()
+	if gpath == "" {
+		t.Skip("This test needs gccgo")
+	}
+
+	verout, err := exec.Command(gpath, "--version").CombinedOutput()
+	if err != nil {
+		t.Logf("%s", verout)
+		t.Fatal(err)
+	}
+	vers := regexp.MustCompile(`([0-9]+)\.([0-9]+)`).FindSubmatch(verout)
+	if len(vers) == 0 {
+		t.Fatalf("could not find version number in %s", verout)
+	}
+	major, err := strconv.Atoi(string(vers[1]))
+	if err != nil {
+		t.Fatal(err)
+	}
+	minor, err := strconv.Atoi(string(vers[2]))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("gccgo version %d.%d", major, minor)
+
+	tmpdir := t.TempDir()
+	initmap := make(map[*types.Package]InitData)
+	imp := GetImporter([]string{tmpdir}, initmap)
+
+	artmpdir := t.TempDir()
+	arinitmap := make(map[*types.Package]InitData)
+	arimp := GetImporter([]string{artmpdir}, arinitmap)
+
+	for _, test := range importerTests {
+		if major < test.gccgoVersion {
+			// Support for type aliases was added in GCC 7.
+			t.Logf("skipping %q: not supported before gccgo version %d", test.pkgpath, test.gccgoVersion)
+			continue
+		}
+
+		gofile := filepath.Join("testdata", test.pkgpath+".go")
+		if _, err := os.Stat(gofile); os.IsNotExist(err) {
+			continue
+		}
+		ofile := filepath.Join(tmpdir, test.pkgpath+".o")
+		afile := filepath.Join(artmpdir, "lib"+test.pkgpath+".a")
+
+		cmd := exec.Command(gpath, "-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)
+		}
+	}
+}
diff --git a/src/go/internal/gccgoimporter/parser.go b/src/go/internal/gccgoimporter/parser.go
new file mode 100644
index 0000000..1b1d07d
--- /dev/null
+++ b/src/go/internal/gccgoimporter/parser.go
@@ -0,0 +1,1284 @@
+// 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"
+	"unicode/utf8"
+)
+
+type parser struct {
+	scanner  *scanner.Scanner
+	version  string                    // format version
+	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
+	typeList []types.Type              // type number -> type
+	typeData []string                  // unparsed type data (v3 and later)
+	fixups   []fixupRecord             // fixups to apply at end of parsing
+	initdata InitData                  // package init priority data
+	aliases  map[int]string            // maps saved type number to alias name
+}
+
+// When reading export data it's possible to encounter a defined type
+// N1 with an underlying defined type N2 while we are still reading in
+// that defined type N2; see issues #29006 and #29198 for instances
+// of this. Example:
+//
+//   type N1 N2
+//   type N2 struct {
+//      ...
+//      p *N1
+//   }
+//
+// To handle such cases, the parser generates a fixup record (below) and
+// delays setting of N1's underlying type until parsing is complete, at
+// which point fixups are applied.
+
+type fixupRecord struct {
+	toUpdate *types.Named // type to modify when fixup is processed
+	target   types.Type   // type that was incomplete when fixup was created
+}
+
+func (p *parser) init(filename string, src io.Reader, imports map[string]*types.Package) {
+	p.scanner = new(scanner.Scanner)
+	p.initScanner(filename, src)
+	p.imports = imports
+	p.aliases = make(map[int]string)
+	p.typeList = make([]types.Type, 1 /* type numbers start at 1 */, 16)
+}
+
+func (p *parser) initScanner(filename string, src io.Reader) {
+	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
+	p.scanner.Whitespace = 1<<'\t' | 1<<' '
+	p.scanner.Filename = filename // for good error messages
+	p.next()
+}
+
+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) expectEOL() {
+	if p.version == "v1" || p.version == "v2" {
+		p.expect(';')
+	}
+	p.expect('\n')
+}
+
+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 != '\n' && 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, n := p.parseTypeExtended(pkg)
+	anon := false
+	if name == "" {
+		anon = true
+		// Alias?
+		if aname, ok := p.aliases[n]; ok {
+			name = aname
+		} else {
+			switch typ := deref(typ).(type) {
+			case *types.Basic:
+				name = typ.Name()
+			case *types.Named:
+				name = typ.Obj().Name()
+			default:
+				p.error("embedded 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()
+	// Ignore names invented for inlinable functions.
+	if strings.HasPrefix(name, "p.") || strings.HasPrefix(name, "r.") || strings.HasPrefix(name, "$ret") {
+		name = ""
+	}
+	if p.tok == '<' && p.scanner.Peek() == 'e' {
+		// EscInfo = "<esc:" int ">" . (optional and ignored)
+		p.next()
+		p.expectKeyword("esc")
+		p.expect(':')
+		p.expect(scanner.Int)
+		p.expect('>')
+	}
+	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()
+	v := types.NewVar(token.NoPos, pkg, name, p.parseType(pkg))
+	if name[0] == '.' || name[0] == '<' {
+		// This is an unexported variable,
+		// or a variable defined in a different package.
+		// We only want to record exported variables.
+		return nil
+	}
+	return v
+}
+
+// Conversion = "convert" "(" Type "," ConstValue ")" .
+func (p *parser) parseConversion(pkg *types.Package) (val constant.Value, typ types.Type) {
+	p.expectKeyword("convert")
+	p.expect('(')
+	typ = p.parseType(pkg)
+	p.expect(',')
+	val, _ = p.parseConstValue(pkg)
+	p.expect(')')
+	return
+}
+
+// ConstValue     = string | "false" | "true" | ["-"] (int ["'"] | FloatOrComplex) | Conversion .
+// FloatOrComplex = float ["i" | ("+"|"-") float "i"] .
+func (p *parser) parseConstValue(pkg *types.Package) (val constant.Value, typ types.Type) {
+	// v3 changed to $false, $true, $convert, to avoid confusion
+	// with variable names in inline function bodies.
+	if p.tok == '$' {
+		p.next()
+		if p.tok != scanner.Ident {
+			p.errorf("expected identifier after '$', got %s (%q)", scanner.TokenString(p.tok), p.lit)
+		}
+	}
+
+	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
+
+		case "convert":
+			return p.parseConversion(pkg)
+
+		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(pkg)
+	if typ == nil {
+		typ = vtyp
+	}
+	return types.NewConst(token.NoPos, pkg, name, typ, val)
+}
+
+// reserved is a singleton type used to fill type map slots that have
+// been reserved (i.e., for which a type number has been parsed) but
+// which don't have their actual type yet. When the type map is updated,
+// the actual type must replace a reserved entry (or we have an internal
+// error). Used for self-verification only - not required for correctness.
+var reserved = new(struct{ types.Type })
+
+// reserve reserves the type map entry n for future use.
+func (p *parser) reserve(n int) {
+	// Notes:
+	// - for pre-V3 export data, the type numbers we see are
+	//   guaranteed to be in increasing order, so we append a
+	//   reserved entry onto the list.
+	// - for V3+ export data, type numbers can appear in
+	//   any order, however the 'types' section tells us the
+	//   total number of types, hence typeList is pre-allocated.
+	if len(p.typeData) == 0 {
+		if n != len(p.typeList) {
+			p.errorf("invalid type number %d (out of sync)", n)
+		}
+		p.typeList = append(p.typeList, reserved)
+	} else {
+		if p.typeList[n] != nil {
+			p.errorf("previously visited type number %d", n)
+		}
+		p.typeList[n] = reserved
+	}
+}
+
+// update sets the type map entries for the entries in nlist to t.
+// An entry in nlist can be a type number in p.typeList,
+// used to resolve named types, or it can be a *types.Pointer,
+// used to resolve pointers to named types in case they are referenced
+// by embedded fields.
+func (p *parser) update(t types.Type, nlist []interface{}) {
+	if t == reserved {
+		p.errorf("internal error: update(%v) invoked on reserved", nlist)
+	}
+	if t == nil {
+		p.errorf("internal error: update(%v) invoked on nil", nlist)
+	}
+	for _, n := range nlist {
+		switch n := n.(type) {
+		case int:
+			if p.typeList[n] == t {
+				continue
+			}
+			if p.typeList[n] != reserved {
+				p.errorf("internal error: update(%v): %d not reserved", nlist, n)
+			}
+			p.typeList[n] = t
+		case *types.Pointer:
+			if *n != (types.Pointer{}) {
+				elem := n.Elem()
+				if elem == t {
+					continue
+				}
+				p.errorf("internal error: update: pointer already set to %v, expected %v", elem, t)
+			}
+			*n = *types.NewPointer(t)
+		default:
+			p.errorf("internal error: %T on nlist", n)
+		}
+	}
+}
+
+// NamedType = TypeName [ "=" ] Type { Method } .
+// TypeName  = ExportedName .
+// Method    = "func" "(" Param ")" Name ParamList ResultList [InlineBody] ";" .
+func (p *parser) parseNamedType(nlist []interface{}) types.Type {
+	pkg, name := p.parseExportedName()
+	scope := pkg.Scope()
+	obj := scope.Lookup(name)
+	if obj != nil && obj.Type() == nil {
+		p.errorf("%v has nil type", obj)
+	}
+
+	if p.tok == scanner.Ident && p.lit == "notinheap" {
+		p.next()
+		// The go/types package has no way of recording that
+		// this type is marked notinheap. Presumably no user
+		// of this package actually cares.
+	}
+
+	// type alias
+	if p.tok == '=' {
+		p.next()
+		p.aliases[nlist[len(nlist)-1].(int)] = name
+		if obj != nil {
+			// use the previously imported (canonical) type
+			t := obj.Type()
+			p.update(t, nlist)
+			p.parseType(pkg) // discard
+			return t
+		}
+		t := p.parseType(pkg, nlist...)
+		obj = types.NewTypeName(token.NoPos, pkg, name, t)
+		scope.Insert(obj)
+		return t
+	}
+
+	// defined type
+	if obj == nil {
+		// A named type may be referred to before the underlying type
+		// is known - set it up.
+		tname := types.NewTypeName(token.NoPos, pkg, name, nil)
+		types.NewNamed(tname, nil, nil)
+		scope.Insert(tname)
+		obj = tname
+	}
+
+	// use the previously imported (canonical), or newly created type
+	t := obj.Type()
+	p.update(t, nlist)
+
+	nt, ok := t.(*types.Named)
+	if !ok {
+		// This can happen for unsafe.Pointer, which is a TypeName holding a Basic type.
+		pt := p.parseType(pkg)
+		if pt != t {
+			p.error("unexpected underlying type for non-named TypeName")
+		}
+		return t
+	}
+
+	underlying := p.parseType(pkg)
+	if nt.Underlying() == nil {
+		if underlying.Underlying() == nil {
+			fix := fixupRecord{toUpdate: nt, target: underlying}
+			p.fixups = append(p.fixups, fix)
+		} else {
+			nt.SetUnderlying(underlying.Underlying())
+		}
+	}
+
+	if p.tok == '\n' {
+		p.next()
+		// collect associated methods
+		for p.tok == scanner.Ident {
+			p.expectKeyword("func")
+			if p.tok == '/' {
+				// Skip a /*nointerface*/ or /*asm ID */ comment.
+				p.expect('/')
+				p.expect('*')
+				if p.expect(scanner.Ident) == "asm" {
+					p.parseUnquotedString()
+				}
+				p.expect('*')
+				p.expect('/')
+			}
+			p.expect('(')
+			receiver, _ := p.parseParam(pkg)
+			p.expect(')')
+			name := p.parseName()
+			params, isVariadic := p.parseParamList(pkg)
+			results := p.parseResultList(pkg)
+			p.skipInlineBody()
+			p.expectEOL()
+
+			sig := types.NewSignature(receiver, params, results, isVariadic)
+			nt.AddMethod(types.NewFunc(token.NoPos, pkg, name, sig))
+		}
+	}
+
+	return nt
+}
+
+func (p *parser) parseInt64() int64 {
+	lit := p.expect(scanner.Int)
+	n, err := strconv.ParseInt(lit, 10, 64)
+	if err != nil {
+		p.error(err)
+	}
+	return n
+}
+
+func (p *parser) parseInt() int {
+	lit := p.expect(scanner.Int)
+	n, err := strconv.ParseInt(lit, 10, 0 /* int */)
+	if err != nil {
+		p.error(err)
+	}
+	return int(n)
+}
+
+// ArrayOrSliceType = "[" [ int ] "]" Type .
+func (p *parser) parseArrayOrSliceType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expect('[')
+	if p.tok == ']' {
+		p.next()
+
+		t := new(types.Slice)
+		p.update(t, nlist)
+
+		*t = *types.NewSlice(p.parseType(pkg))
+		return t
+	}
+
+	t := new(types.Array)
+	p.update(t, nlist)
+
+	len := p.parseInt64()
+	p.expect(']')
+
+	*t = *types.NewArray(p.parseType(pkg), len)
+	return t
+}
+
+// MapType = "map" "[" Type "]" Type .
+func (p *parser) parseMapType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expectKeyword("map")
+
+	t := new(types.Map)
+	p.update(t, nlist)
+
+	p.expect('[')
+	key := p.parseType(pkg)
+	p.expect(']')
+	elem := p.parseType(pkg)
+
+	*t = *types.NewMap(key, elem)
+	return t
+}
+
+// ChanType = "chan" ["<-" | "-<"] Type .
+func (p *parser) parseChanType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expectKeyword("chan")
+
+	t := new(types.Chan)
+	p.update(t, nlist)
+
+	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
+		}
+	}
+
+	*t = *types.NewChan(dir, p.parseType(pkg))
+	return t
+}
+
+// StructType = "struct" "{" { Field } "}" .
+func (p *parser) parseStructType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expectKeyword("struct")
+
+	t := new(types.Struct)
+	p.update(t, nlist)
+
+	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('}')
+
+	*t = *types.NewStruct(fields, tags)
+	return t
+}
+
+// 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 '<':
+		p.next()
+		if p.tok == scanner.Ident && p.lit == "inl" {
+			return nil
+		}
+		taa, _ := p.parseTypeAfterAngle(pkg)
+		return types.NewTuple(types.NewParam(token.NoPos, pkg, "", taa))
+
+	case '(':
+		params, _ := p.parseParamList(pkg)
+		return params
+
+	default:
+		return nil
+	}
+}
+
+// FunctionType = ParamList ResultList .
+func (p *parser) parseFunctionType(pkg *types.Package, nlist []interface{}) *types.Signature {
+	t := new(types.Signature)
+	p.update(t, nlist)
+
+	params, isVariadic := p.parseParamList(pkg)
+	results := p.parseResultList(pkg)
+
+	*t = *types.NewSignature(nil, params, results, isVariadic)
+	return t
+}
+
+// Func = Name FunctionType [InlineBody] .
+func (p *parser) parseFunc(pkg *types.Package) *types.Func {
+	if p.tok == '/' {
+		// Skip an /*asm ID */ comment.
+		p.expect('/')
+		p.expect('*')
+		if p.expect(scanner.Ident) == "asm" {
+			p.parseUnquotedString()
+		}
+		p.expect('*')
+		p.expect('/')
+	}
+
+	name := p.parseName()
+	f := types.NewFunc(token.NoPos, pkg, name, p.parseFunctionType(pkg, nil))
+	p.skipInlineBody()
+
+	if name[0] == '.' || name[0] == '<' || strings.ContainsRune(name, '$') {
+		// This is an unexported function,
+		// or a function defined in a different package,
+		// or a type$equal or type$hash function.
+		// We only want to record exported functions.
+		return nil
+	}
+
+	return f
+}
+
+// InterfaceType = "interface" "{" { ("?" Type | Func) ";" } "}" .
+func (p *parser) parseInterfaceType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expectKeyword("interface")
+
+	t := new(types.Interface)
+	p.update(t, nlist)
+
+	var methods []*types.Func
+	var embeddeds []types.Type
+
+	p.expect('{')
+	for p.tok != '}' && p.tok != scanner.EOF {
+		if p.tok == '?' {
+			p.next()
+			embeddeds = append(embeddeds, p.parseType(pkg))
+		} else {
+			method := p.parseFunc(pkg)
+			if method != nil {
+				methods = append(methods, method)
+			}
+		}
+		p.expect(';')
+	}
+	p.expect('}')
+
+	*t = *types.NewInterfaceType(methods, embeddeds)
+	return t
+}
+
+// PointerType = "*" ("any" | Type) .
+func (p *parser) parsePointerType(pkg *types.Package, nlist []interface{}) types.Type {
+	p.expect('*')
+	if p.tok == scanner.Ident {
+		p.expectKeyword("any")
+		t := types.Typ[types.UnsafePointer]
+		p.update(t, nlist)
+		return t
+	}
+
+	t := new(types.Pointer)
+	p.update(t, nlist)
+
+	*t = *types.NewPointer(p.parseType(pkg, t))
+
+	return t
+}
+
+// TypeSpec = NamedType | MapType | ChanType | StructType | InterfaceType | PointerType | ArrayOrSliceType | FunctionType .
+func (p *parser) parseTypeSpec(pkg *types.Package, nlist []interface{}) types.Type {
+	switch p.tok {
+	case scanner.String:
+		return p.parseNamedType(nlist)
+
+	case scanner.Ident:
+		switch p.lit {
+		case "map":
+			return p.parseMapType(pkg, nlist)
+
+		case "chan":
+			return p.parseChanType(pkg, nlist)
+
+		case "struct":
+			return p.parseStructType(pkg, nlist)
+
+		case "interface":
+			return p.parseInterfaceType(pkg, nlist)
+		}
+
+	case '*':
+		return p.parsePointerType(pkg, nlist)
+
+	case '[':
+		return p.parseArrayOrSliceType(pkg, nlist)
+
+	case '(':
+		return p.parseFunctionType(pkg, nlist)
+	}
+
+	p.errorf("expected type name or literal, got %s", scanner.TokenString(p.tok))
+	return nil
+}
+
+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 [ TypeSpec ] ) ">" .
+//
+// parseType updates the type map to t for all type numbers n.
+//
+func (p *parser) parseType(pkg *types.Package, n ...interface{}) types.Type {
+	p.expect('<')
+	t, _ := p.parseTypeAfterAngle(pkg, n...)
+	return t
+}
+
+// (*parser).Type after reading the "<".
+func (p *parser) parseTypeAfterAngle(pkg *types.Package, n ...interface{}) (t types.Type, n1 int) {
+	p.expectKeyword("type")
+
+	n1 = 0
+	switch p.tok {
+	case scanner.Int:
+		n1 = p.parseInt()
+		if p.tok == '>' {
+			if len(p.typeData) > 0 && p.typeList[n1] == nil {
+				p.parseSavedType(pkg, n1, n)
+			}
+			t = p.typeList[n1]
+			if len(p.typeData) == 0 && t == reserved {
+				p.errorf("invalid type cycle, type %d not yet defined (nlist=%v)", n1, n)
+			}
+			p.update(t, n)
+		} else {
+			p.reserve(n1)
+			t = p.parseTypeSpec(pkg, append(n, n1))
+		}
+
+	case '-':
+		p.next()
+		n1 := p.parseInt()
+		t = lookupBuiltinType(n1)
+		p.update(t, n)
+
+	default:
+		p.errorf("expected type number, got %s (%q)", scanner.TokenString(p.tok), p.lit)
+		return nil, 0
+	}
+
+	if t == nil || t == reserved {
+		p.errorf("internal error: bad return from parseType(%v)", n)
+	}
+
+	p.expect('>')
+	return
+}
+
+// parseTypeExtended is identical to parseType, but if the type in
+// question is a saved type, returns the index as well as the type
+// pointer (index returned is zero if we parsed a builtin).
+func (p *parser) parseTypeExtended(pkg *types.Package, n ...interface{}) (t types.Type, n1 int) {
+	p.expect('<')
+	t, n1 = p.parseTypeAfterAngle(pkg, n...)
+	return
+}
+
+// InlineBody = "<inl:NN>" .{NN}
+// Reports whether a body was skipped.
+func (p *parser) skipInlineBody() {
+	// We may or may not have seen the '<' already, depending on
+	// whether the function had a result type or not.
+	if p.tok == '<' {
+		p.next()
+		p.expectKeyword("inl")
+	} else if p.tok != scanner.Ident || p.lit != "inl" {
+		return
+	} else {
+		p.next()
+	}
+
+	p.expect(':')
+	want := p.parseInt()
+	p.expect('>')
+
+	defer func(w uint64) {
+		p.scanner.Whitespace = w
+	}(p.scanner.Whitespace)
+	p.scanner.Whitespace = 0
+
+	got := 0
+	for got < want {
+		r := p.scanner.Next()
+		if r == scanner.EOF {
+			p.error("unexpected EOF")
+		}
+		got += utf8.RuneLen(r)
+	}
+}
+
+// Types = "types" maxp1 exportedp1 (offset length)* .
+func (p *parser) parseTypes(pkg *types.Package) {
+	maxp1 := p.parseInt()
+	exportedp1 := p.parseInt()
+	p.typeList = make([]types.Type, maxp1, maxp1)
+
+	type typeOffset struct {
+		offset int
+		length int
+	}
+	var typeOffsets []typeOffset
+
+	total := 0
+	for i := 1; i < maxp1; i++ {
+		len := p.parseInt()
+		typeOffsets = append(typeOffsets, typeOffset{total, len})
+		total += len
+	}
+
+	defer func(w uint64) {
+		p.scanner.Whitespace = w
+	}(p.scanner.Whitespace)
+	p.scanner.Whitespace = 0
+
+	// We should now have p.tok pointing to the final newline.
+	// The next runes from the scanner should be the type data.
+
+	var sb strings.Builder
+	for sb.Len() < total {
+		r := p.scanner.Next()
+		if r == scanner.EOF {
+			p.error("unexpected EOF")
+		}
+		sb.WriteRune(r)
+	}
+	allTypeData := sb.String()
+
+	p.typeData = []string{""} // type 0, unused
+	for _, to := range typeOffsets {
+		p.typeData = append(p.typeData, allTypeData[to.offset:to.offset+to.length])
+	}
+
+	for i := 1; i < int(exportedp1); i++ {
+		p.parseSavedType(pkg, i, nil)
+	}
+}
+
+// parseSavedType parses one saved type definition.
+func (p *parser) parseSavedType(pkg *types.Package, i int, nlist []interface{}) {
+	defer func(s *scanner.Scanner, tok rune, lit string) {
+		p.scanner = s
+		p.tok = tok
+		p.lit = lit
+	}(p.scanner, p.tok, p.lit)
+
+	p.scanner = new(scanner.Scanner)
+	p.initScanner(p.scanner.Filename, strings.NewReader(p.typeData[i]))
+	p.expectKeyword("type")
+	id := p.parseInt()
+	if id != i {
+		p.errorf("type ID mismatch: got %d, want %d", id, i)
+	}
+	if p.typeList[i] == reserved {
+		p.errorf("internal error: %d already reserved in parseSavedType", i)
+	}
+	if p.typeList[i] == nil {
+		p.reserve(i)
+		p.parseTypeSpec(pkg, append(nlist, i))
+	}
+	if p.typeList[i] == nil || p.typeList[i] == reserved {
+		p.errorf("internal error: parseSavedType(%d,%v) reserved/nil", i, nlist)
+	}
+}
+
+// PackageInit = unquotedString unquotedString int .
+func (p *parser) parsePackageInit() PackageInit {
+	name := p.parseUnquotedString()
+	initfunc := p.parseUnquotedString()
+	priority := -1
+	if p.version == "v1" {
+		priority = p.parseInt()
+	}
+	return PackageInit{Name: name, InitFunc: initfunc, Priority: priority}
+}
+
+// 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" | "v2" | "v3" ) ";" |
+//                     "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", "v2", "v3":
+		p.version = p.lit
+		p.next()
+		p.expect(';')
+		p.expect('\n')
+
+	case "priority":
+		p.next()
+		p.initdata.Priority = p.parseInt()
+		p.expectEOL()
+
+	case "init":
+		p.next()
+		for p.tok != '\n' && p.tok != ';' && p.tok != scanner.EOF {
+			p.initdata.Inits = append(p.initdata.Inits, p.parsePackageInit())
+		}
+		p.expectEOL()
+
+	case "init_graph":
+		p.next()
+		// The graph data is thrown away for now.
+		for p.tok != '\n' && p.tok != ';' && p.tok != scanner.EOF {
+			p.parseInt64()
+			p.parseInt64()
+		}
+		p.expectEOL()
+
+	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.expectEOL()
+
+	default:
+		p.errorf("unexpected identifier: %q", p.lit)
+	}
+}
+
+// Directive = InitDataDirective |
+//             "package" unquotedString [ unquotedString ] [ unquotedString ] ";" |
+//             "pkgpath" unquotedString ";" |
+//             "prefix" unquotedString ";" |
+//             "import" unquotedString unquotedString string ";" |
+//             "indirectimport" unquotedString unquotedstring ";" |
+//             "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", "v2", "v3", "priority", "init", "init_graph", "checksum":
+		p.parseInitDataDirective()
+
+	case "package":
+		p.next()
+		p.pkgname = p.parseUnquotedString()
+		p.maybeCreatePackage()
+		if p.version != "v1" && p.tok != '\n' && p.tok != ';' {
+			p.parseUnquotedString()
+			p.parseUnquotedString()
+		}
+		p.expectEOL()
+
+	case "pkgpath":
+		p.next()
+		p.pkgpath = p.parseUnquotedString()
+		p.maybeCreatePackage()
+		p.expectEOL()
+
+	case "prefix":
+		p.next()
+		p.pkgpath = p.parseUnquotedString()
+		p.expectEOL()
+
+	case "import":
+		p.next()
+		pkgname := p.parseUnquotedString()
+		pkgpath := p.parseUnquotedString()
+		p.getPkg(pkgpath, pkgname)
+		p.parseString()
+		p.expectEOL()
+
+	case "indirectimport":
+		p.next()
+		pkgname := p.parseUnquotedString()
+		pkgpath := p.parseUnquotedString()
+		p.getPkg(pkgpath, pkgname)
+		p.expectEOL()
+
+	case "types":
+		p.next()
+		p.parseTypes(p.pkg)
+		p.expectEOL()
+
+	case "func":
+		p.next()
+		fun := p.parseFunc(p.pkg)
+		if fun != nil {
+			p.pkg.Scope().Insert(fun)
+		}
+		p.expectEOL()
+
+	case "type":
+		p.next()
+		p.parseType(p.pkg)
+		p.expectEOL()
+
+	case "var":
+		p.next()
+		v := p.parseVar(p.pkg)
+		if v != nil {
+			p.pkg.Scope().Insert(v)
+		}
+		p.expectEOL()
+
+	case "const":
+		p.next()
+		c := p.parseConst(p.pkg)
+		p.pkg.Scope().Insert(c)
+		p.expectEOL()
+
+	default:
+		p.errorf("unexpected identifier: %q", p.lit)
+	}
+}
+
+// Package = { Directive } .
+func (p *parser) parsePackage() *types.Package {
+	for p.tok != scanner.EOF {
+		p.parseDirective()
+	}
+	for _, f := range p.fixups {
+		if f.target.Underlying() == nil {
+			p.errorf("internal error: fixup can't be applied, loop required")
+		}
+		f.toUpdate.SetUnderlying(f.target.Underlying())
+	}
+	p.fixups = nil
+	for _, typ := range p.typeList {
+		if it, ok := typ.(*types.Interface); ok {
+			it.Complete()
+		}
+	}
+	p.pkg.MarkComplete()
+	return p.pkg
+}
diff --git a/src/go/internal/gccgoimporter/parser_test.go b/src/go/internal/gccgoimporter/parser_test.go
new file mode 100644
index 0000000..00128b4
--- /dev/null
+++ b/src/go/internal/gccgoimporter/parser_test.go
@@ -0,0 +1,78 @@
+// 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>\nfunc (? <type 1>) M ();\n>", 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.version = "v2"
+		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)
+		}
+
+		// interfaces must be explicitly completed
+		if ityp, _ := typ.(*types.Interface); ityp != nil {
+			ityp.Complete()
+		}
+
+		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/src/go/internal/gccgoimporter/testdata/aliases.go b/src/go/internal/gccgoimporter/testdata/aliases.go
new file mode 100644
index 0000000..cfb59b3
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/aliases.go
@@ -0,0 +1,65 @@
+package aliases
+
+type (
+	T0 [10]int
+	T1 []byte
+	T2 struct {
+		x int
+	}
+	T3 interface {
+		m() T2
+	}
+	T4 func(int, T0) chan T2
+)
+
+// basic aliases
+type (
+	Ai = int
+	A0 = T0
+	A1 = T1
+	A2 = T2
+	A3 = T3
+	A4 = T4
+
+	A10 = [10]int
+	A11 = []byte
+	A12 = struct {
+		x int
+	}
+	A13 = interface {
+		m() A2
+	}
+	A14 = func(int, A0) chan A2
+)
+
+// alias receiver types
+func (T0) m1() {}
+func (A0) m2() {}
+
+// alias receiver types (long type declaration chains)
+type (
+	V0 = V1
+	V1 = (V2)
+	V2 = (V3)
+	V3 = T0
+)
+
+func (V1) n() {}
+
+// cycles
+type C0 struct {
+	f1 C1
+	f2 C2
+}
+
+type (
+	C1 *C0
+	C2 = C1
+)
+
+type (
+	C5 struct {
+		f *C6
+	}
+	C6 = C5
+)
diff --git a/src/go/internal/gccgoimporter/testdata/aliases.gox b/src/go/internal/gccgoimporter/testdata/aliases.gox
new file mode 100644
index 0000000..2428c06
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/aliases.gox
@@ -0,0 +1,33 @@
+v2;
+package aliases;
+prefix go;
+package aliases go.aliases go.aliases;
+type <type 1 "A0" = <type 2 "T0" <type 3 [10 ] <type -11>>
+ func (? <esc:0x1> <type 2>) .go.aliases.m1 ();
+ func (? <esc:0x1> <type 1>) .go.aliases.m2 ();
+ func (? <esc:0x1> <type 4 "V1" = <type 5 "V2" = <type 6 "V3" = <type 2>>>>) .go.aliases.n ();
+>>;
+type <type 7 "A1" = <type 8 "T1" <type 9 [] <type -20>>>>;
+type <type 10 "A10" = <type 11 [10 ] <type -11>>>;
+type <type 12 "A11" = <type 13 [] <type -20>>>;
+type <type 14 "A12" = <type 15 struct { .go.aliases.x <type -11>; }>>;
+type <type 16 "A13" = <type 17 interface { .go.aliases.m () <type 18 "A2" = <type 19 "T2" <type 20 struct { .go.aliases.x <type -11>; }>>>; }>>;
+type <type 21 "A14" = <type 22 (? <type -11>, ? <type 1>) <type 23 chan <type 18>>>>;
+type <type 18>;
+type <type 24 "A3" = <type 25 "T3" <type 26 interface { .go.aliases.m () <type 19>; }>>>;
+type <type 27 "A4" = <type 28 "T4" <type 29 (? <type -11>, ? <type 2>) <type 30 chan <type 19>>>>>;
+type <type 31 "Ai" = <type -11>>;
+type <type 32 "C0" <type 33 struct { .go.aliases.f1 <type 34 "C1" <type 35 *<type 32>>>; .go.aliases.f2 <type 36 "C2" = <type 34>>; }>>;
+type <type 34>;
+type <type 36>;
+type <type 37 "C5" <type 38 struct { .go.aliases.f <type 39 *<type 40 "C6" = <type 37>>>; }>>;
+type <type 40>;
+type <type 2>;
+type <type 8>;
+type <type 19>;
+type <type 25>;
+type <type 28>;
+type <type 41 "V0" = <type 4>>;
+type <type 4>;
+type <type 5>;
+type <type 6>;
diff --git a/src/go/internal/gccgoimporter/testdata/complexnums.go b/src/go/internal/gccgoimporter/testdata/complexnums.go
new file mode 100644
index 0000000..a51b6b0
--- /dev/null
+++ b/src/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/src/go/internal/gccgoimporter/testdata/complexnums.gox b/src/go/internal/gccgoimporter/testdata/complexnums.gox
new file mode 100644
index 0000000..b66524f
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/complexnums.gox
@@ -0,0 +1,8 @@
+v1;
+package complexnums;
+pkgpath complexnums;
+priority 1;
+const NN = -0.1E1-0.1E1i ;
+const NP = -0.1E1+0.1E1i ;
+const PN = 0.1E1-0.1E1i ;
+const PP = 0.1E1+0.1E1i ;
diff --git a/src/go/internal/gccgoimporter/testdata/conversions.go b/src/go/internal/gccgoimporter/testdata/conversions.go
new file mode 100644
index 0000000..653927a
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/conversions.go
@@ -0,0 +1,5 @@
+package conversions
+
+type Units string
+
+const Bits = Units("bits")
diff --git a/src/go/internal/gccgoimporter/testdata/conversions.gox b/src/go/internal/gccgoimporter/testdata/conversions.gox
new file mode 100644
index 0000000..7de6cda
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/conversions.gox
@@ -0,0 +1,6 @@
+v2;
+package conversions;
+prefix go;
+package conversions go.conversions go.conversions;
+const Bits <type 1 "Units" <type -16>> = convert(<type 1>, "bits");
+type <type 1>;
diff --git a/src/go/internal/gccgoimporter/testdata/escapeinfo.go b/src/go/internal/gccgoimporter/testdata/escapeinfo.go
new file mode 100644
index 0000000..103ad95
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/escapeinfo.go
@@ -0,0 +1,13 @@
+// Test case for escape info in export data. To compile and extract .gox file:
+// gccgo -fgo-optimize-allocs -c escapeinfo.go
+// objcopy -j .go_export escapeinfo.o escapeinfo.gox
+
+package escapeinfo
+
+type T struct{ data []byte }
+
+func NewT(data []byte) *T {
+	return &T{data}
+}
+
+func (*T) Read(p []byte) {}
diff --git a/src/go/internal/gccgoimporter/testdata/escapeinfo.gox b/src/go/internal/gccgoimporter/testdata/escapeinfo.gox
new file mode 100644
index 0000000..1db8156
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/escapeinfo.gox
diff --git a/src/go/internal/gccgoimporter/testdata/imports.go b/src/go/internal/gccgoimporter/testdata/imports.go
new file mode 100644
index 0000000..7907316
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/imports.go
@@ -0,0 +1,5 @@
+package imports
+
+import "fmt"
+
+var Hello = fmt.Sprintf("Hello, world")
diff --git a/src/go/internal/gccgoimporter/testdata/imports.gox b/src/go/internal/gccgoimporter/testdata/imports.gox
new file mode 100644
index 0000000..958a4f5
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/imports.gox
@@ -0,0 +1,7 @@
+v1;
+package imports;
+pkgpath imports;
+priority 7;
+import fmt fmt "fmt";
+init imports imports..import 7 math math..import 1 runtime runtime..import 1 strconv strconv..import 2 io io..import 3 reflect reflect..import 3 syscall syscall..import 3 time time..import 4 os os..import 5 fmt fmt..import 6;
+var Hello <type -16>;
diff --git a/src/go/internal/gccgoimporter/testdata/issue27856.go b/src/go/internal/gccgoimporter/testdata/issue27856.go
new file mode 100644
index 0000000..bf361e1
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue27856.go
@@ -0,0 +1,9 @@
+package lib
+
+type M struct {
+	E E
+}
+type F struct {
+	_ *M
+}
+type E = F
diff --git a/src/go/internal/gccgoimporter/testdata/issue27856.gox b/src/go/internal/gccgoimporter/testdata/issue27856.gox
new file mode 100644
index 0000000..6665e64
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue27856.gox
@@ -0,0 +1,9 @@
+v2;
+package main;
+pkgpath main;
+import runtime runtime "runtime";
+init runtime runtime..import sys runtime_internal_sys..import;
+init_graph 0 1;
+type <type 1 "E" = <type 2 "F" <type 3 struct { .main._ <type 4 *<type 5 "M" <type 6 struct { E <type 1>; }>>>; }>>>;
+type <type 2>;
+type <type 5>;
diff --git a/src/go/internal/gccgoimporter/testdata/issue29198.go b/src/go/internal/gccgoimporter/testdata/issue29198.go
new file mode 100644
index 0000000..75c2162
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue29198.go
@@ -0,0 +1,37 @@
+// Copyright 2018 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 server
+
+import (
+	"context"
+	"errors"
+)
+
+type A struct {
+	x int
+}
+
+func (a *A) AMethod(y int) *Server {
+	return nil
+}
+
+// FooServer is a server that provides Foo services
+type FooServer Server
+
+func (f *FooServer) WriteEvents(ctx context.Context, x int) error {
+	return errors.New("hey!")
+}
+
+type Server struct {
+	FooServer *FooServer
+	user      string
+	ctx       context.Context
+}
+
+func New(sctx context.Context, u string) (*Server, error) {
+	s := &Server{user: u, ctx: sctx}
+	s.FooServer = (*FooServer)(s)
+	return s, nil
+}
diff --git a/src/go/internal/gccgoimporter/testdata/issue29198.gox b/src/go/internal/gccgoimporter/testdata/issue29198.gox
new file mode 100644
index 0000000..905c866
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue29198.gox
@@ -0,0 +1,86 @@
+v2;
+package server;
+pkgpath issue29198;
+import context context "context";
+import errors errors "errors";
+init context context..import fmt fmt..import poll internal_poll..import testlog internal_testlog..import io io..import os os..import reflect reflect..import runtime runtime..import sys runtime_internal_sys..import strconv strconv..import sync sync..import syscall syscall..import time time..import unicode unicode..import;
+init_graph 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0 11 0 12 0 13 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 1 11 1 12 1 13 2 4 2 7 2 8 2 10 2 11 2 12 4 7 4 8 4 10 5 2 5 3 5 4 5 7 5 8 5 10 5 11 5 12 6 7 6 8 6 9 6 10 6 13 7 8 9 7 9 8 10 7 10 8 11 7 11 8 11 10 12 7 12 8 12 10 12 11;
+type <type 1 "A" <type 2 struct { .issue29198.x <type -11>; }>
+ func (a <esc:0x1> <type 3 *<type 1>>) AMethod (y <type -11>) <type 4 *<type 5 "Server" <type 6 struct { FooServer <type 7 *<type 8 "FooServer" <type 5>
+ func (f <esc:0x1> <type 9 *<type 8>>) WriteEvents (ctx <esc:0x1> <type 10 "context.Context" <type 11 interface { Deadline () (deadline <type 12 "time.Time" "time" <type 13 struct { .time.wall <type -8>; .time.ext <type -4>; .time.loc <type 14 *<type 15 "time.Location" <type 16 struct { .time.name <type -16>; .time.zone <type 17 [] <type 18 ".time.zone" <type 19 struct { .time.name <type -16>; .time.offset <type -11>; .time.isDST <type -15>; }>>>; .time.tx <type 20 [] <type 21 ".time.zoneTrans" <type 22 struct { .time.when <type -4>; .time.index <type -5>; .time.isstd <type -15>; .time.isutc <type -15>; }>>>; .time.cacheStart <type -4>; .time.cacheEnd <type -4>; .time.cacheZone <type 23 *<type 18>>; }>
+ func (l <esc:0x22> <type 24 *<type 15>>) String () <type -16>;
+ func (l <esc:0x1> <type 24>) .time.lookupFirstZone () <type -11>;
+ func (l <esc:0x12> <type 24>) .time.get () <type 24>;
+ func (l <esc:0x32> <type 24>) .time.lookup (sec <type -4>) (name <type -16>, offset <type -11>, isDST <type -15>, start <type -4>, end <type -4>);
+ func (l <esc:0x1> <type 24>) .time.lookupName (name <esc:0x1> <type -16>, unix <type -4>) (offset <type -11>, ok <type -15>);
+ func (l <esc:0x1> <type 24>) .time.firstZoneUsed () <type -15>;
+>>; }>
+ func (t <esc:0x12> <type 12>) In (loc <type 14>) <type 12>;
+ func (t <esc:0x1> <type 12>) .time.date (full <type -15>) (year <type -11>, month <type 25 "time.Month" <type -11>
+ func (m <type 25>) String () <type -16>;
+>, day <type -11>, yday <type -11>);
+ func (t <esc:0x1> <type 12>) Sub (u <esc:0x1> <type 12>) <type 26 "time.Duration" <type -4>
+ func (d <type 26>) Truncate (m <type 26>) <type 26>;
+ func (d <type 26>) String () <type -16>;
+ func (d <type 26>) Round (m <type 26>) <type 26>;
+ func (d <type 26>) Seconds () <type -10>;
+ func (d <type 26>) Nanoseconds () <type -4>;
+ func (d <type 26>) Minutes () <type -10>;
+ func (d <type 26>) Hours () <type -10>;
+>;
+ func (t <esc:0x12> <type 12>) Add (d <type 26>) <type 12>;
+ func (t <esc:0x12> <type 12>) UTC () <type 12>;
+ func (t <type 12>) AddDate (years <type -11>, months <type -11>, days <type -11>) <type 12>;
+ func (t <esc:0x1> <type 12>) MarshalBinary () (? <type 27 [] <type -20>>, ? <type -19>);
+ func (t <esc:0x1> <type 12>) Nanosecond () <type -11>;
+ func (t <esc:0x12> <type 12>) Round (d <type 26>) <type 12>;
+ func (t <esc:0x1> <type 12>) Minute () <type -11>;
+ func (t <esc:0x1> <type 12>) Clock () (hour <type -11>, min <type -11>, sec <type -11>);
+ func (t <esc:0x1> <type 12>) ISOWeek () (year <type -11>, week <type -11>);
+ func (t <esc:0x1> <type 12>) Day () <type -11>;
+ func (t <esc:0x1> <type 28 *<type 12>>) .time.mono () <type -4>;
+ func (t <esc:0x1> <type 12>) UnixNano () <type -4>;
+ func (t <esc:0x1> <type 28>) .time.sec () <type -4>;
+ func (t <esc:0x1> <type 12>) Second () <type -11>;
+ func (t <esc:0x1> <type 12>) Before (u <esc:0x1> <type 12>) <type -15>;
+ func (t <esc:0x1> <type 28>) UnmarshalBinary (data <esc:0x1> <type 29 [] <type -20>>) <type -19>;
+ func (t <esc:0x1> <type 12>) Month () <type 25>;
+ func (t <esc:0x1> <type 12>) YearDay () <type -11>;
+ func (t <esc:0x12> <type 12>) Location () <type 14>;
+ func (t <esc:0x32> <type 12>) Zone () (name <type -16>, offset <type -11>);
+ func (t <esc:0x12> <type 12>) Local () <type 12>;
+ func (t <esc:0x1> <type 28>) .time.setLoc (loc <type 14>);
+ func (t <esc:0x12> <type 12>) Truncate (d <type 26>) <type 12>;
+ func (t <esc:0x1> <type 12>) MarshalJSON () (? <type 30 [] <type -20>>, ? <type -19>);
+ func (t <esc:0x1> <type 12>) AppendFormat (b <esc:0x12> <type 31 [] <type -20>>, layout <esc:0x1> <type -16>) <type 32 [] <type -20>>;
+ func (t <esc:0x1> <type 28>) GobDecode (data <esc:0x1> <type 33 [] <type -20>>) <type -19>;
+ func (t <esc:0x1> <type 28>) UnmarshalJSON (data <esc:0x1> <type 34 [] <type -20>>) <type -19>;
+ func (t <esc:0x1> <type 12>) MarshalText () (? <type 35 [] <type -20>>, ? <type -19>);
+ func (t <esc:0x1> <type 12>) GobEncode () (? <type 36 [] <type -20>>, ? <type -19>);
+ func (t <esc:0x1> <type 28>) .time.stripMono ();
+ func (t <esc:0x1> <type 12>) After (u <esc:0x1> <type 12>) <type -15>;
+ func (t <esc:0x1> <type 12>) Hour () <type -11>;
+ func (t <esc:0x1> <type 28>) UnmarshalText (data <esc:0x1> <type 37 [] <type -20>>) <type -19>;
+ func (t <esc:0x1> <type 12>) Equal (u <esc:0x1> <type 12>) <type -15>;
+ func (t <esc:0x1> <type 28>) .time.setMono (m <type -4>);
+ func (t <esc:0x1> <type 12>) Year () <type -11>;
+ func (t <esc:0x1> <type 12>) IsZero () <type -15>;
+ func (t <esc:0x1> <type 28>) .time.addSec (d <type -4>);
+ func (t <esc:0x1> <type 12>) Weekday () <type 38 "time.Weekday" <type -11>
+ func (d <type 38>) String () <type -16>;
+>;
+ func (t <esc:0x1> <type 12>) String () <type -16>;
+ func (t <esc:0x1> <type 28>) .time.nsec () <type -3>;
+ func (t <esc:0x1> <type 12>) Format (layout <esc:0x1> <type -16>) <type -16>;
+ func (t <esc:0x1> <type 28>) .time.unixSec () <type -4>;
+ func (t <esc:0x1> <type 12>) Unix () <type -4>;
+ func (t <esc:0x1> <type 12>) .time.abs () <type -8>;
+ func (t <esc:0x32> <type 12>) .time.locabs () (name <type -16>, offset <type -11>, abs <type -8>);
+ func (t <esc:0x1> <type 12>) Date () (year <type -11>, month <type 25>, day <type -11>);
+>, ok <type -15>); Done () <type 39 chan <- <type 40 struct { }>>; Err () <type -19>; Value (key <type 41 interface { }>) <type 42 interface { }>; }>>, x <type -11>) <type -19>;
+>>; .issue29198.user <type -16>; .issue29198.ctx <type 10>; }>>>;
+>;
+type <type 8>;
+func New (sctx <type 10>, u <type -16>) (? <type 43 *<type 5>>, ? <type -19>);
+type <type 5>;
+checksum 86C8D76B2582F55A8BD2CA9E00060358EC1CE214;
diff --git a/src/go/internal/gccgoimporter/testdata/issue30628.go b/src/go/internal/gccgoimporter/testdata/issue30628.go
new file mode 100644
index 0000000..8fd7c13
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue30628.go
@@ -0,0 +1,18 @@
+package issue30628
+
+import (
+	"os"
+	"sync"
+)
+
+const numR = int32(os.O_TRUNC + 5)
+
+type Apple struct {
+	hey sync.RWMutex
+	x   int
+	RQ  [numR]struct {
+		Count    uintptr
+		NumBytes uintptr
+		Last     uintptr
+	}
+}
diff --git a/src/go/internal/gccgoimporter/testdata/issue30628.gox b/src/go/internal/gccgoimporter/testdata/issue30628.gox
new file mode 100644
index 0000000..0ff6259
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue30628.gox
@@ -0,0 +1,28 @@
+v3;
+package issue30628
+pkgpath issue30628
+import os os "os"
+import sync sync "sync"
+init cpu internal..z2fcpu..import poll internal..z2fpoll..import testlog internal..z2ftestlog..import io io..import os os..import runtime runtime..import sys runtime..z2finternal..z2fsys..import sync sync..import syscall syscall..import time time..import
+init_graph 1 0 1 3 1 5 1 6 1 7 1 8 1 9 3 0 3 5 3 6 3 7 4 0 4 1 4 2 4 3 4 5 4 6 4 7 4 8 4 9 5 0 5 6 7 0 7 5 7 6 8 0 8 5 8 6 8 7 9 0 9 5 9 6 9 7 9 8
+types 13 2 24 84 208 17 30 41 147 86 17 64 25 75
+type 1 "Apple" <type 2>
+type 2 struct { .issue30628.hey <type 3>; .issue30628.x <type -11>; RQ <type 11>; }
+type 3 "sync.RWMutex" <type 7>
+ func (rw <type 4>) Lock ()
+ func (rw <esc:0x12> <type 4>) RLocker () ($ret8 <type 5>)
+ func (rw <type 4>) RUnlock ()
+ func (rw <type 4>) Unlock ()
+ func (rw <type 4>) RLock ()
+type 4 *<type 3>
+type 5 "sync.Locker" <type 6>
+type 6 interface { Lock (); Unlock (); }
+type 7 struct { .sync.w <type 8>; .sync.writerSem <type -7>; .sync.readerSem <type -7>; .sync.readerCount <type -3>; .sync.readerWait <type -3>; }
+type 8 "sync.Mutex" <type 10>
+ func (m <type 9>) Unlock ()
+ func (m <type 9>) Lock ()
+type 9 *<type 8>
+type 10 struct { .sync.state <type -3>; .sync.sema <type -7>; }
+type 11 [517 ] <type 12>
+type 12 struct { Count <type -13>; NumBytes <type -13>; Last <type -13>; }
+checksum 199DCF6D3EE2FCF39F715B4E42B5F87F5B15D3AF
diff --git a/src/go/internal/gccgoimporter/testdata/issue31540.go b/src/go/internal/gccgoimporter/testdata/issue31540.go
new file mode 100644
index 0000000..2c6799e
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue31540.go
@@ -0,0 +1,26 @@
+// Copyright 2019 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 issue31540
+
+type Y struct {
+	q int
+}
+
+type Z map[int]int
+
+type X = map[Y]Z
+
+type A1 = X
+
+type A2 = A1
+
+type S struct {
+	b int
+	A2
+}
+
+func Hallo() S {
+	return S{}
+}
diff --git a/src/go/internal/gccgoimporter/testdata/issue31540.gox b/src/go/internal/gccgoimporter/testdata/issue31540.gox
new file mode 100644
index 0000000..abdc696
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue31540.gox
@@ -0,0 +1,16 @@
+v3;
+package issue31540
+pkgpath issue31540
+types 11 7 23 23 20 22 20 21 57 31 45 36
+type 1 "A1" = <type 4>
+type 2 "A2" = <type 1>
+type 3 "S" <type 7>
+type 4 "X" = <type 8>
+type 5 "Y" <type 9>
+type 6 "Z" <type 10>
+type 7 struct { .go.mapalias.b <type -11>; ? <type 2>; }
+type 8 map [<type 5>] <type 6>
+type 9 struct { .go.mapalias.q <type -11>; }
+type 10 map [<type -11>] <type -11>
+func Hallo () <type 3>
+checksum C3FAF2524A90BC11225EE65D059BF27DFB69134B
diff --git a/src/go/internal/gccgoimporter/testdata/issue34182.go b/src/go/internal/gccgoimporter/testdata/issue34182.go
new file mode 100644
index 0000000..2a5c333
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue34182.go
@@ -0,0 +1,17 @@
+// Copyright 2019 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 issue34182
+
+type T1 struct {
+	f *T2
+}
+
+type T2 struct {
+	f T3
+}
+
+type T3 struct {
+	*T2
+}
diff --git a/src/go/internal/gccgoimporter/testdata/issue34182.gox b/src/go/internal/gccgoimporter/testdata/issue34182.gox
new file mode 100644
index 0000000..671a7d6
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/issue34182.gox
@@ -0,0 +1,13 @@
+v3;
+package issue34182
+pkgpath issue34182
+init issue34182 ~go.issue34182
+types 8 4 21 21 21 17 30 45 45
+type 1 "T1" <type 6>
+type 2 "T2" <type 7>
+type 3 "T3" <type 5>
+type 4 *<type 2>
+type 5 struct { ? <type 4>; }
+type 6 struct { .go.issue34182.f <type 4>; }
+type 7 struct { .go.issue34182.f <type 3>; }
+checksum FF02C49BAF44B06C087ED4E573F7CC880C79C208
diff --git a/src/go/internal/gccgoimporter/testdata/libimportsar.a b/src/go/internal/gccgoimporter/testdata/libimportsar.a
new file mode 100644
index 0000000..6f30758
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/libimportsar.a
diff --git a/src/go/internal/gccgoimporter/testdata/nointerface.go b/src/go/internal/gccgoimporter/testdata/nointerface.go
new file mode 100644
index 0000000..6a545f2
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/nointerface.go
@@ -0,0 +1,12 @@
+// Copyright 2018 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 nointerface
+
+type I int
+
+//go:nointerface
+func (p *I) Get() int { return int(*p) }
+
+func (p *I) Set(v int) { *p = I(v) }
diff --git a/src/go/internal/gccgoimporter/testdata/nointerface.gox b/src/go/internal/gccgoimporter/testdata/nointerface.gox
new file mode 100644
index 0000000..7b73d17
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/nointerface.gox
@@ -0,0 +1,8 @@
+v3;
+package nointerface
+pkgpath nointerface
+types 3 2 133 17
+type 1 "I" <type -11>
+ func /*nointerface*/ (p <esc:0x1> <type 2>) Get () <type -11>
+ func (p <esc:0x1> <type 2>) Set (v <type -11>)
+type 2 *<type 1>
diff --git a/src/go/internal/gccgoimporter/testdata/notinheap.go b/src/go/internal/gccgoimporter/testdata/notinheap.go
new file mode 100644
index 0000000..b1ac967
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/notinheap.go
@@ -0,0 +1,4 @@
+package notinheap
+
+//go:notinheap
+type S struct{}
diff --git a/src/go/internal/gccgoimporter/testdata/notinheap.gox b/src/go/internal/gccgoimporter/testdata/notinheap.gox
new file mode 100644
index 0000000..cc438e7
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/notinheap.gox
@@ -0,0 +1,7 @@
+v3;
+package notinheap
+pkgpath notinheap
+init notinheap ~notinheap
+types 3 2 30 18
+type 1 "S" notinheap <type 2>
+type 2 struct { }
diff --git a/src/go/internal/gccgoimporter/testdata/pointer.go b/src/go/internal/gccgoimporter/testdata/pointer.go
new file mode 100644
index 0000000..4ebc671
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/pointer.go
@@ -0,0 +1,3 @@
+package pointer
+
+type Int8Ptr *int8
diff --git a/src/go/internal/gccgoimporter/testdata/pointer.gox b/src/go/internal/gccgoimporter/testdata/pointer.gox
new file mode 100644
index 0000000..d96ebbd
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/pointer.gox
@@ -0,0 +1,4 @@
+v1;
+package pointer;
+pkgpath pointer;
+type <type 1 "Int8Ptr" <type 2 *<type -1>>>;
diff --git a/src/go/internal/gccgoimporter/testdata/time.gox b/src/go/internal/gccgoimporter/testdata/time.gox
new file mode 100644
index 0000000..80c2dbc
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/time.gox
diff --git a/src/go/internal/gccgoimporter/testdata/unicode.gox b/src/go/internal/gccgoimporter/testdata/unicode.gox
new file mode 100644
index 0000000..e70e539
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/unicode.gox
diff --git a/src/go/internal/gccgoimporter/testdata/v1reflect.gox b/src/go/internal/gccgoimporter/testdata/v1reflect.gox
new file mode 100644
index 0000000..ea46841
--- /dev/null
+++ b/src/go/internal/gccgoimporter/testdata/v1reflect.gox
diff --git a/src/go/internal/gcimporter/exportdata.go b/src/go/internal/gcimporter/exportdata.go
new file mode 100644
index 0000000..c12e459
--- /dev/null
+++ b/src/go/internal/gcimporter/exportdata.go
@@ -0,0 +1,91 @@
+// 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"
+	"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 = fmt.Errorf("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. The hdr result
+// is the string before the export data, either "$$" or "$$B".
+//
+func FindExportData(r *bufio.Reader) (hdr string, err error) {
+	// Read first line to make sure this is an object file.
+	line, err := r.ReadSlice('\n')
+	if err != nil {
+		err = fmt.Errorf("can't find export data (%v)", err)
+		return
+	}
+
+	if string(line) == "!<arch>\n" {
+		// Archive file. Scan to __.PKGDEF.
+		var name string
+		if name, _, err = readGopackHeader(r); err != nil {
+			return
+		}
+
+		// First entry should be __.PKGDEF.
+		if name != "__.PKGDEF" {
+			err = fmt.Errorf("go archive is missing __.PKGDEF")
+			return
+		}
+
+		// Read first line of __.PKGDEF data, so that line
+		// is once again the first line of the input.
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+	}
+
+	// Now at __.PKGDEF in archive or still at beginning of file.
+	// Either way, line should begin with "go object ".
+	if !strings.HasPrefix(string(line), "go object ") {
+		err = fmt.Errorf("not a Go object file")
+		return
+	}
+
+	// Skip over object header to export data.
+	// Begins after first line starting with $$.
+	for line[0] != '$' {
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+	}
+	hdr = string(line)
+
+	return
+}
diff --git a/src/go/internal/gcimporter/gcimporter.go b/src/go/internal/gcimporter/gcimporter.go
new file mode 100644
index 0000000..73cf633
--- /dev/null
+++ b/src/go/internal/gcimporter/gcimporter.go
@@ -0,0 +1,171 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gcimporter implements Import for gc-generated object files.
+package gcimporter // import "go/internal/gcimporter"
+
+import (
+	"bufio"
+	"fmt"
+	"go/build"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// debugging/development support
+const debug = false
+
+var pkgExts = [...]string{".a", ".o"}
+
+// FindPkg returns the filename and unique package id for an import
+// path based on package information provided by build.Import (using
+// the build.Default build.Context). A relative srcDir is interpreted
+// relative to the current working directory.
+// If no file was found, an empty filename is returned.
+//
+func FindPkg(path, srcDir string) (filename, id string) {
+	if path == "" {
+		return
+	}
+
+	var noext string
+	switch {
+	default:
+		// "x" -> "$GOPATH/pkg/$GOOS_$GOARCH/x.ext", "x"
+		// Don't require the source files to be present.
+		if abs, err := filepath.Abs(srcDir); err == nil { // see issue 14282
+			srcDir = abs
+		}
+		bp, _ := build.Import(path, srcDir, build.FindOnly|build.AllowBinary)
+		if bp.PkgObj == "" {
+			id = path // make sure we have an id to print in error message
+			return
+		}
+		noext = strings.TrimSuffix(bp.PkgObj, ".a")
+		id = bp.ImportPath
+
+	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
+		id = path
+	}
+
+	if false { // for debugging
+		if path != id {
+			fmt.Printf("%s -> %s\n", path, id)
+		}
+	}
+
+	// try extensions
+	for _, ext := range pkgExts {
+		filename = noext + ext
+		if f, err := os.Stat(filename); err == nil && !f.IsDir() {
+			return
+		}
+	}
+
+	filename = "" // not found
+	return
+}
+
+// Import imports a gc-generated package given its import path and srcDir, adds
+// the corresponding package object to the packages map, and returns the object.
+// The packages map must contain all packages already imported.
+//
+func Import(fset *token.FileSet, packages map[string]*types.Package, path, srcDir string, lookup func(path string) (io.ReadCloser, error)) (pkg *types.Package, err error) {
+	var rc io.ReadCloser
+	var id string
+	if lookup != nil {
+		// With custom lookup specified, assume that caller has
+		// converted path to a canonical import path for use in the map.
+		if path == "unsafe" {
+			return types.Unsafe, nil
+		}
+		id = path
+
+		// No need to re-import if the package was imported completely before.
+		if pkg = packages[id]; pkg != nil && pkg.Complete() {
+			return
+		}
+		f, err := lookup(path)
+		if err != nil {
+			return nil, err
+		}
+		rc = f
+	} else {
+		var filename string
+		filename, id = FindPkg(path, srcDir)
+		if filename == "" {
+			if path == "unsafe" {
+				return types.Unsafe, nil
+			}
+			return nil, fmt.Errorf("can't find import: %q", id)
+		}
+
+		// 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 nil, err
+		}
+		defer func() {
+			if err != nil {
+				// add file name to error
+				err = fmt.Errorf("%s: %v", filename, err)
+			}
+		}()
+		rc = f
+	}
+	defer rc.Close()
+
+	var hdr string
+	buf := bufio.NewReader(rc)
+	if hdr, err = FindExportData(buf); err != nil {
+		return
+	}
+
+	switch hdr {
+	case "$$\n":
+		err = fmt.Errorf("import %q: old textual export format no longer supported (recompile library)", path)
+
+	case "$$B\n":
+		var exportFormat byte
+		exportFormat, err = buf.ReadByte()
+
+		// The indexed export format starts with an 'i'; the older
+		// binary export format starts with a 'c', 'd', or 'v'
+		// (from "version"). Select appropriate importer.
+		if err == nil && exportFormat == 'i' {
+			pkg, err = iImportData(fset, packages, buf, id)
+		} else {
+			err = fmt.Errorf("import %q: old binary export format no longer supported (recompile library)", path)
+		}
+
+	default:
+		err = fmt.Errorf("import %q: unknown export data header: %q", path, hdr)
+	}
+
+	return
+}
+
+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/src/go/internal/gcimporter/gcimporter_test.go b/src/go/internal/gcimporter/gcimporter_test.go
new file mode 100644
index 0000000..3c76aaf
--- /dev/null
+++ b/src/go/internal/gcimporter/gcimporter_test.go
@@ -0,0 +1,619 @@
+// 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 (
+	"bytes"
+	"fmt"
+	"internal/testenv"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"go/token"
+	"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 "darwin-arm64":
+		t.Skipf("no compiled packages available for import on %s", platform)
+	}
+}
+
+// compile runs the compiler on filename, with dirname as the working directory,
+// and writes the output file to outdirname.
+func compile(t *testing.T, dirname, filename, outdirname string) string {
+	// filename must end with ".go"
+	if !strings.HasSuffix(filename, ".go") {
+		t.Fatalf("filename doesn't end in .go: %s", filename)
+	}
+	basename := filepath.Base(filename)
+	outname := filepath.Join(outdirname, basename[:len(basename)-2]+"o")
+	cmd := exec.Command(testenv.GoToolPath(t), "tool", "compile", "-o", outname, 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)
+	}
+	return outname
+}
+
+func testPath(t *testing.T, path, srcDir string) *types.Package {
+	t0 := time.Now()
+	fset := token.NewFileSet()
+	pkg, err := Import(fset, make(map[string]*types.Package), path, srcDir, nil)
+	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 := os.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), dir) != nil {
+						nimports++
+					}
+				}
+			}
+		case f.IsDir():
+			nimports += testDir(t, filepath.Join(dir, f.Name()), endTime)
+		}
+	}
+	return
+}
+
+func mktmpdir(t *testing.T) string {
+	tmpdir, err := os.MkdirTemp("", "gcimporter_test")
+	if err != nil {
+		t.Fatal("mktmpdir:", err)
+	}
+	if err := os.Mkdir(filepath.Join(tmpdir, "testdata"), 0700); err != nil {
+		os.RemoveAll(tmpdir)
+		t.Fatal("mktmpdir:", err)
+	}
+	return tmpdir
+}
+
+func TestImportTestdata(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)
+	}
+
+	tmpdir := mktmpdir(t)
+	defer os.RemoveAll(tmpdir)
+
+	compile(t, "testdata", "exports.go", filepath.Join(tmpdir, "testdata"))
+
+	if pkg := testPath(t, "./testdata/exports", tmpdir); pkg != nil {
+		// The package's Imports list must include all packages
+		// explicitly imported by exports.go, plus all packages
+		// referenced indirectly via exported objects in exports.go.
+		// With the textual export format, the list may also include
+		// additional packages that are not strictly required for
+		// import processing alone (they are exported to err "on
+		// the safe side").
+		// TODO(gri) update the want list to be precise, now that
+		// the textual export data is gone.
+		got := fmt.Sprint(pkg.Imports())
+		for _, want := range []string{"go/ast", "go/token"} {
+			if !strings.Contains(got, want) {
+				t.Errorf(`Package("exports").Imports() = %s, does not contain %s`, got, want)
+			}
+		}
+	}
+}
+
+func TestVersionHandling(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)
+	}
+
+	const dir = "./testdata/versions"
+	list, err := os.ReadDir(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tmpdir := mktmpdir(t)
+	defer os.RemoveAll(tmpdir)
+	corruptdir := filepath.Join(tmpdir, "testdata", "versions")
+	if err := os.Mkdir(corruptdir, 0700); err != nil {
+		t.Fatal(err)
+	}
+
+	fset := token.NewFileSet()
+
+	for _, f := range list {
+		name := f.Name()
+		if !strings.HasSuffix(name, ".a") {
+			continue // not a package file
+		}
+		if strings.Contains(name, "corrupted") {
+			continue // don't process a leftover corrupted file
+		}
+		pkgpath := "./" + name[:len(name)-2]
+
+		if testing.Verbose() {
+			t.Logf("importing %s", name)
+		}
+
+		// test that export data can be imported
+		_, err := Import(fset, make(map[string]*types.Package), pkgpath, dir, nil)
+		if err != nil {
+			// ok to fail if it fails with a no longer supported error for select files
+			if strings.Contains(err.Error(), "no longer supported") {
+				switch name {
+				case "test_go1.7_0.a", "test_go1.7_1.a",
+					"test_go1.8_4.a", "test_go1.8_5.a",
+					"test_go1.11_6b.a", "test_go1.11_999b.a":
+					continue
+				}
+				// fall through
+			}
+			// ok to fail if it fails with a newer version error for select files
+			if strings.Contains(err.Error(), "newer version") {
+				switch name {
+				case "test_go1.11_999i.a":
+					continue
+				}
+				// fall through
+			}
+			t.Errorf("import %q failed: %v", pkgpath, err)
+			continue
+		}
+
+		// create file with corrupted export data
+		// 1) read file
+		data, err := os.ReadFile(filepath.Join(dir, name))
+		if err != nil {
+			t.Fatal(err)
+		}
+		// 2) find export data
+		i := bytes.Index(data, []byte("\n$$B\n")) + 5
+		j := bytes.Index(data[i:], []byte("\n$$\n")) + i
+		if i < 0 || j < 0 || i > j {
+			t.Fatalf("export data section not found (i = %d, j = %d)", i, j)
+		}
+		// 3) corrupt the data (increment every 7th byte)
+		for k := j - 13; k >= i; k -= 7 {
+			data[k]++
+		}
+		// 4) write the file
+		pkgpath += "_corrupted"
+		filename := filepath.Join(corruptdir, pkgpath) + ".a"
+		os.WriteFile(filename, data, 0666)
+
+		// test that importing the corrupted file results in an error
+		_, err = Import(fset, make(map[string]*types.Package), pkgpath, corruptdir, nil)
+		if err == nil {
+			t.Errorf("import corrupted %q succeeded", pkgpath)
+		} else if msg := err.Error(); !strings.Contains(msg, "version skew") {
+			t.Errorf("import %q error incorrect (%s)", pkgpath, msg)
+		}
+	}
+}
+
+func TestImportStdLib(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)
+	}
+
+	dt := maxTime
+	if testing.Short() && testenv.Builder() == "" {
+		dt = 10 * time.Millisecond
+	}
+	nimports := testDir(t, "", time.Now().Add(dt)) // installed packages
+	t.Logf("tested %d imports", nimports)
+}
+
+var importedObjectTests = []struct {
+	name string
+	want string
+}{
+	// non-interfaces
+	{"crypto.Hash", "type Hash uint"},
+	{"go/ast.ObjKind", "type ObjKind int"},
+	{"go/types.Qualifier", "type Qualifier func(*Package) string"},
+	{"go/types.Comparable", "func Comparable(T Type) bool"},
+	{"math.Pi", "const Pi untyped float"},
+	{"math.Sin", "func Sin(x float64) float64"},
+	{"go/ast.NotNilFilter", "func NotNilFilter(_ string, v reflect.Value) bool"},
+	{"go/internal/gcimporter.FindPkg", "func FindPkg(path string, srcDir string) (filename string, id string)"},
+
+	// interfaces
+	{"context.Context", "type Context interface{Deadline() (deadline time.Time, ok bool); Done() <-chan struct{}; Err() error; Value(key interface{}) interface{}}"},
+	{"crypto.Decrypter", "type Decrypter interface{Decrypt(rand io.Reader, msg []byte, opts DecrypterOpts) (plaintext []byte, err error); Public() PublicKey}"},
+	{"encoding.BinaryMarshaler", "type BinaryMarshaler interface{MarshalBinary() (data []byte, err error)}"},
+	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
+	{"io.ReadWriter", "type ReadWriter interface{Reader; Writer}"},
+	{"go/ast.Node", "type Node interface{End() go/token.Pos; Pos() go/token.Pos}"},
+	{"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
+}
+
+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)
+	}
+
+	fset := token.NewFileSet()
+	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(fset, make(map[string]*types.Package), importPath, ".", nil)
+		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)
+		}
+
+		if named, _ := obj.Type().(*types.Named); named != nil {
+			verifyInterfaceMethodRecvs(t, named, 0)
+		}
+	}
+}
+
+// verifyInterfaceMethodRecvs verifies that method receiver types
+// are named if the methods belong to a named interface type.
+func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
+	// avoid endless recursion in case of an embedding bug that lead to a cycle
+	if level > 10 {
+		t.Errorf("%s: embeds itself", named)
+		return
+	}
+
+	iface, _ := named.Underlying().(*types.Interface)
+	if iface == nil {
+		return // not an interface
+	}
+
+	// check explicitly declared methods
+	for i := 0; i < iface.NumExplicitMethods(); i++ {
+		m := iface.ExplicitMethod(i)
+		recv := m.Type().(*types.Signature).Recv()
+		if recv == nil {
+			t.Errorf("%s: missing receiver type", m)
+			continue
+		}
+		if recv.Type() != named {
+			t.Errorf("%s: got recv type %s; want %s", m, recv.Type(), named)
+		}
+	}
+
+	// check embedded interfaces (if they are named, too)
+	for i := 0; i < iface.NumEmbeddeds(); i++ {
+		// embedding of interfaces cannot have cycles; recursion will terminate
+		if etype, _ := iface.EmbeddedType(i).(*types.Named); etype != nil {
+			verifyInterfaceMethodRecvs(t, etype, level+1)
+		}
+	}
+}
+
+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)
+	}
+
+	pkg := importPkg(t, "strings", ".")
+
+	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)
+	}
+
+	imports := make(map[string]*types.Package)
+	fset := token.NewFileSet()
+	_, err := Import(fset, imports, "net/http", ".", nil)
+	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)
+	}
+}
+
+func TestIssue13566(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	tmpdir := mktmpdir(t)
+	defer os.RemoveAll(tmpdir)
+	testoutdir := filepath.Join(tmpdir, "testdata")
+
+	// b.go needs to be compiled from the output directory so that the compiler can
+	// find the compiled package a. We pass the full path to compile() so that we
+	// don't have to copy the file to that directory.
+	bpath, err := filepath.Abs(filepath.Join("testdata", "b.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	compile(t, "testdata", "a.go", testoutdir)
+	compile(t, testoutdir, bpath, testoutdir)
+
+	// import must succeed (test for issue at hand)
+	pkg := importPkg(t, "./testdata/b", tmpdir)
+
+	// make sure all indirectly imported packages have names
+	for _, imp := range pkg.Imports() {
+		if imp.Name() == "" {
+			t.Errorf("no name for %s package", imp.Path())
+		}
+	}
+}
+
+func TestIssue13898(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)
+	}
+
+	// import go/internal/gcimporter which imports go/types partially
+	fset := token.NewFileSet()
+	imports := make(map[string]*types.Package)
+	_, err := Import(fset, imports, "go/internal/gcimporter", ".", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// look for go/types package
+	var goTypesPkg *types.Package
+	for path, pkg := range imports {
+		if path == "go/types" {
+			goTypesPkg = pkg
+			break
+		}
+	}
+	if goTypesPkg == nil {
+		t.Fatal("go/types not found")
+	}
+
+	// look for go/types.Object type
+	obj := lookupObj(t, goTypesPkg.Scope(), "Object")
+	typ, ok := obj.Type().(*types.Named)
+	if !ok {
+		t.Fatalf("go/types.Object type is %v; wanted named type", typ)
+	}
+
+	// lookup go/types.Object.Pkg method
+	m, index, indirect := types.LookupFieldOrMethod(typ, false, nil, "Pkg")
+	if m == nil {
+		t.Fatalf("go/types.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
+	}
+
+	// the method must belong to go/types
+	if m.Pkg().Path() != "go/types" {
+		t.Fatalf("found %v; want go/types", m.Pkg())
+	}
+}
+
+func TestIssue15517(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	tmpdir := mktmpdir(t)
+	defer os.RemoveAll(tmpdir)
+
+	compile(t, "testdata", "p.go", filepath.Join(tmpdir, "testdata"))
+
+	// Multiple imports of p must succeed without redeclaration errors.
+	// We use an import path that's not cleaned up so that the eventual
+	// file path for the package is different from the package path; this
+	// will expose the error if it is present.
+	//
+	// (Issue: Both the textual and the binary importer used the file path
+	// of the package to be imported as key into the shared packages map.
+	// However, the binary importer then used the package path to identify
+	// the imported package to mark it as complete; effectively marking the
+	// wrong package as complete. By using an "unclean" package path, the
+	// file and package path are different, exposing the problem if present.
+	// The same issue occurs with vendoring.)
+	imports := make(map[string]*types.Package)
+	fset := token.NewFileSet()
+	for i := 0; i < 3; i++ {
+		if _, err := Import(fset, imports, "./././testdata/p", tmpdir, nil); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestIssue15920(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	compileAndImportPkg(t, "issue15920")
+}
+
+func TestIssue20046(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	// "./issue20046".V.M must exist
+	pkg := compileAndImportPkg(t, "issue20046")
+	obj := lookupObj(t, pkg.Scope(), "V")
+	if m, index, indirect := types.LookupFieldOrMethod(obj.Type(), false, nil, "M"); m == nil {
+		t.Fatalf("V.M not found (index = %v, indirect = %v)", index, indirect)
+	}
+}
+func TestIssue25301(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	compileAndImportPkg(t, "issue25301")
+}
+
+func TestIssue25596(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)
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	compileAndImportPkg(t, "issue25596")
+}
+
+func importPkg(t *testing.T, path, srcDir string) *types.Package {
+	fset := token.NewFileSet()
+	pkg, err := Import(fset, make(map[string]*types.Package), path, srcDir, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return pkg
+}
+
+func compileAndImportPkg(t *testing.T, name string) *types.Package {
+	tmpdir := mktmpdir(t)
+	defer os.RemoveAll(tmpdir)
+	compile(t, "testdata", name+".go", filepath.Join(tmpdir, "testdata"))
+	return importPkg(t, "./testdata/"+name, tmpdir)
+}
+
+func lookupObj(t *testing.T, scope *types.Scope, name string) types.Object {
+	if obj := scope.Lookup(name); obj != nil {
+		return obj
+	}
+	t.Fatalf("%s not found", name)
+	return nil
+}
diff --git a/src/go/internal/gcimporter/iimport.go b/src/go/internal/gcimporter/iimport.go
new file mode 100644
index 0000000..76d47d0
--- /dev/null
+++ b/src/go/internal/gcimporter/iimport.go
@@ -0,0 +1,607 @@
+// Copyright 2018 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.
+
+// Indexed package import.
+// See cmd/compile/internal/gc/iexport.go for the export data format.
+
+package gcimporter
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"math/big"
+	"sort"
+)
+
+type intReader struct {
+	*bufio.Reader
+	path string
+}
+
+func (r *intReader) int64() int64 {
+	i, err := binary.ReadVarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+func (r *intReader) uint64() uint64 {
+	i, err := binary.ReadUvarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+const predeclReserved = 32
+
+type itag uint64
+
+const (
+	// Types
+	definedType itag = iota
+	pointerType
+	sliceType
+	arrayType
+	chanType
+	mapType
+	signatureType
+	structType
+	interfaceType
+)
+
+// iImportData imports a package from the serialized package data
+// and returns the number of bytes consumed and a reference to the package.
+// If the export data version is not recognized or the format is otherwise
+// compromised, an error is returned.
+func iImportData(fset *token.FileSet, imports map[string]*types.Package, dataReader *bufio.Reader, path string) (pkg *types.Package, err error) {
+	const currentVersion = 1
+	version := int64(-1)
+	defer func() {
+		if e := recover(); e != nil {
+			if version > currentVersion {
+				err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
+			} else {
+				err = fmt.Errorf("cannot import %q (%v), possibly version skew - reinstall package", path, e)
+			}
+		}
+	}()
+
+	r := &intReader{dataReader, path}
+
+	version = int64(r.uint64())
+	switch version {
+	case currentVersion, 0:
+	default:
+		errorf("unknown iexport format version %d", version)
+	}
+
+	sLen := int64(r.uint64())
+	dLen := int64(r.uint64())
+
+	data := make([]byte, sLen+dLen)
+	if _, err := io.ReadFull(r, data); err != nil {
+		errorf("cannot read %d bytes of stringData and declData: %s", len(data), err)
+	}
+	stringData := data[:sLen]
+	declData := data[sLen:]
+
+	p := iimporter{
+		ipath:   path,
+		version: int(version),
+
+		stringData:  stringData,
+		stringCache: make(map[uint64]string),
+		pkgCache:    make(map[uint64]*types.Package),
+
+		declData: declData,
+		pkgIndex: make(map[*types.Package]map[string]uint64),
+		typCache: make(map[uint64]types.Type),
+
+		fake: fakeFileSet{
+			fset:  fset,
+			files: make(map[string]*token.File),
+		},
+	}
+
+	for i, pt := range predeclared {
+		p.typCache[uint64(i)] = pt
+	}
+
+	pkgList := make([]*types.Package, r.uint64())
+	for i := range pkgList {
+		pkgPathOff := r.uint64()
+		pkgPath := p.stringAt(pkgPathOff)
+		pkgName := p.stringAt(r.uint64())
+		_ = r.uint64() // package height; unused by go/types
+
+		if pkgPath == "" {
+			pkgPath = path
+		}
+		pkg := imports[pkgPath]
+		if pkg == nil {
+			pkg = types.NewPackage(pkgPath, pkgName)
+			imports[pkgPath] = pkg
+		} else if pkg.Name() != pkgName {
+			errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+		}
+
+		p.pkgCache[pkgPathOff] = pkg
+
+		nameIndex := make(map[string]uint64)
+		for nSyms := r.uint64(); nSyms > 0; nSyms-- {
+			name := p.stringAt(r.uint64())
+			nameIndex[name] = r.uint64()
+		}
+
+		p.pkgIndex[pkg] = nameIndex
+		pkgList[i] = pkg
+	}
+
+	localpkg := pkgList[0]
+
+	names := make([]string, 0, len(p.pkgIndex[localpkg]))
+	for name := range p.pkgIndex[localpkg] {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	for _, name := range names {
+		p.doDecl(localpkg, name)
+	}
+
+	for _, typ := range p.interfaceList {
+		typ.Complete()
+	}
+
+	// record all referenced packages as imports
+	list := append(([]*types.Package)(nil), pkgList[1:]...)
+	sort.Sort(byPath(list))
+	localpkg.SetImports(list)
+
+	// package was imported completely and without errors
+	localpkg.MarkComplete()
+	return localpkg, nil
+}
+
+type iimporter struct {
+	ipath   string
+	version int
+
+	stringData  []byte
+	stringCache map[uint64]string
+	pkgCache    map[uint64]*types.Package
+
+	declData []byte
+	pkgIndex map[*types.Package]map[string]uint64
+	typCache map[uint64]types.Type
+
+	fake          fakeFileSet
+	interfaceList []*types.Interface
+}
+
+func (p *iimporter) doDecl(pkg *types.Package, name string) {
+	// See if we've already imported this declaration.
+	if obj := pkg.Scope().Lookup(name); obj != nil {
+		return
+	}
+
+	off, ok := p.pkgIndex[pkg][name]
+	if !ok {
+		errorf("%v.%v not in index", pkg, name)
+	}
+
+	r := &importReader{p: p, currPkg: pkg}
+	r.declReader.Reset(p.declData[off:])
+
+	r.obj(name)
+}
+
+func (p *iimporter) stringAt(off uint64) string {
+	if s, ok := p.stringCache[off]; ok {
+		return s
+	}
+
+	slen, n := binary.Uvarint(p.stringData[off:])
+	if n <= 0 {
+		errorf("varint failed")
+	}
+	spos := off + uint64(n)
+	s := string(p.stringData[spos : spos+slen])
+	p.stringCache[off] = s
+	return s
+}
+
+func (p *iimporter) pkgAt(off uint64) *types.Package {
+	if pkg, ok := p.pkgCache[off]; ok {
+		return pkg
+	}
+	path := p.stringAt(off)
+	errorf("missing package %q in %q", path, p.ipath)
+	return nil
+}
+
+func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
+	if t, ok := p.typCache[off]; ok && (base == nil || !isInterface(t)) {
+		return t
+	}
+
+	if off < predeclReserved {
+		errorf("predeclared type missing from cache: %v", off)
+	}
+
+	r := &importReader{p: p}
+	r.declReader.Reset(p.declData[off-predeclReserved:])
+	t := r.doType(base)
+
+	if base == nil || !isInterface(t) {
+		p.typCache[off] = t
+	}
+	return t
+}
+
+type importReader struct {
+	p          *iimporter
+	declReader bytes.Reader
+	currPkg    *types.Package
+	prevFile   string
+	prevLine   int64
+	prevColumn int64
+}
+
+func (r *importReader) obj(name string) {
+	tag := r.byte()
+	pos := r.pos()
+
+	switch tag {
+	case 'A':
+		typ := r.typ()
+
+		r.declare(types.NewTypeName(pos, r.currPkg, name, typ))
+
+	case 'C':
+		typ, val := r.value()
+
+		r.declare(types.NewConst(pos, r.currPkg, name, typ, val))
+
+	case 'F':
+		sig := r.signature(nil)
+
+		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
+
+	case 'T':
+		// Types can be recursive. We need to setup a stub
+		// declaration before recursing.
+		obj := types.NewTypeName(pos, r.currPkg, name, nil)
+		named := types.NewNamed(obj, nil, nil)
+		r.declare(obj)
+
+		underlying := r.p.typAt(r.uint64(), named).Underlying()
+		named.SetUnderlying(underlying)
+
+		if !isInterface(underlying) {
+			for n := r.uint64(); n > 0; n-- {
+				mpos := r.pos()
+				mname := r.ident()
+				recv := r.param()
+				msig := r.signature(recv)
+
+				named.AddMethod(types.NewFunc(mpos, r.currPkg, mname, msig))
+			}
+		}
+
+	case 'V':
+		typ := r.typ()
+
+		r.declare(types.NewVar(pos, r.currPkg, name, typ))
+
+	default:
+		errorf("unexpected tag: %v", tag)
+	}
+}
+
+func (r *importReader) declare(obj types.Object) {
+	obj.Pkg().Scope().Insert(obj)
+}
+
+func (r *importReader) value() (typ types.Type, val constant.Value) {
+	typ = r.typ()
+
+	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
+	case types.IsBoolean:
+		val = constant.MakeBool(r.bool())
+
+	case types.IsString:
+		val = constant.MakeString(r.string())
+
+	case types.IsInteger:
+		var x big.Int
+		r.mpint(&x, b)
+		val = constant.Make(&x)
+
+	case types.IsFloat:
+		val = r.mpfloat(b)
+
+	case types.IsComplex:
+		re := r.mpfloat(b)
+		im := r.mpfloat(b)
+		val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
+
+	default:
+		errorf("unexpected type %v", typ) // panics
+		panic("unreachable")
+	}
+
+	return
+}
+
+func intSize(b *types.Basic) (signed bool, maxBytes uint) {
+	if (b.Info() & types.IsUntyped) != 0 {
+		return true, 64
+	}
+
+	switch b.Kind() {
+	case types.Float32, types.Complex64:
+		return true, 3
+	case types.Float64, types.Complex128:
+		return true, 7
+	}
+
+	signed = (b.Info() & types.IsUnsigned) == 0
+	switch b.Kind() {
+	case types.Int8, types.Uint8:
+		maxBytes = 1
+	case types.Int16, types.Uint16:
+		maxBytes = 2
+	case types.Int32, types.Uint32:
+		maxBytes = 4
+	default:
+		maxBytes = 8
+	}
+
+	return
+}
+
+func (r *importReader) mpint(x *big.Int, typ *types.Basic) {
+	signed, maxBytes := intSize(typ)
+
+	maxSmall := 256 - maxBytes
+	if signed {
+		maxSmall = 256 - 2*maxBytes
+	}
+	if maxBytes == 1 {
+		maxSmall = 256
+	}
+
+	n, _ := r.declReader.ReadByte()
+	if uint(n) < maxSmall {
+		v := int64(n)
+		if signed {
+			v >>= 1
+			if n&1 != 0 {
+				v = ^v
+			}
+		}
+		x.SetInt64(v)
+		return
+	}
+
+	v := -n
+	if signed {
+		v = -(n &^ 1) >> 1
+	}
+	if v < 1 || uint(v) > maxBytes {
+		errorf("weird decoding: %v, %v => %v", n, signed, v)
+	}
+	b := make([]byte, v)
+	io.ReadFull(&r.declReader, b)
+	x.SetBytes(b)
+	if signed && n&1 != 0 {
+		x.Neg(x)
+	}
+}
+
+func (r *importReader) mpfloat(typ *types.Basic) constant.Value {
+	var mant big.Int
+	r.mpint(&mant, typ)
+	var f big.Float
+	f.SetInt(&mant)
+	if f.Sign() != 0 {
+		f.SetMantExp(&f, int(r.int64()))
+	}
+	return constant.Make(&f)
+}
+
+func (r *importReader) ident() string {
+	return r.string()
+}
+
+func (r *importReader) qualifiedIdent() (*types.Package, string) {
+	name := r.string()
+	pkg := r.pkg()
+	return pkg, name
+}
+
+func (r *importReader) pos() token.Pos {
+	if r.p.version >= 1 {
+		r.posv1()
+	} else {
+		r.posv0()
+	}
+
+	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
+		return token.NoPos
+	}
+	return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
+}
+
+func (r *importReader) posv0() {
+	delta := r.int64()
+	if delta != deltaNewFile {
+		r.prevLine += delta
+	} else if l := r.int64(); l == -1 {
+		r.prevLine += deltaNewFile
+	} else {
+		r.prevFile = r.string()
+		r.prevLine = l
+	}
+}
+
+func (r *importReader) posv1() {
+	delta := r.int64()
+	r.prevColumn += delta >> 1
+	if delta&1 != 0 {
+		delta = r.int64()
+		r.prevLine += delta >> 1
+		if delta&1 != 0 {
+			r.prevFile = r.string()
+		}
+	}
+}
+
+func (r *importReader) typ() types.Type {
+	return r.p.typAt(r.uint64(), nil)
+}
+
+func isInterface(t types.Type) bool {
+	_, ok := t.(*types.Interface)
+	return ok
+}
+
+func (r *importReader) pkg() *types.Package { return r.p.pkgAt(r.uint64()) }
+func (r *importReader) string() string      { return r.p.stringAt(r.uint64()) }
+
+func (r *importReader) doType(base *types.Named) types.Type {
+	switch k := r.kind(); k {
+	default:
+		errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
+		return nil
+
+	case definedType:
+		pkg, name := r.qualifiedIdent()
+		r.p.doDecl(pkg, name)
+		return pkg.Scope().Lookup(name).(*types.TypeName).Type()
+	case pointerType:
+		return types.NewPointer(r.typ())
+	case sliceType:
+		return types.NewSlice(r.typ())
+	case arrayType:
+		n := r.uint64()
+		return types.NewArray(r.typ(), int64(n))
+	case chanType:
+		dir := chanDir(int(r.uint64()))
+		return types.NewChan(dir, r.typ())
+	case mapType:
+		return types.NewMap(r.typ(), r.typ())
+	case signatureType:
+		r.currPkg = r.pkg()
+		return r.signature(nil)
+
+	case structType:
+		r.currPkg = r.pkg()
+
+		fields := make([]*types.Var, r.uint64())
+		tags := make([]string, len(fields))
+		for i := range fields {
+			fpos := r.pos()
+			fname := r.ident()
+			ftyp := r.typ()
+			emb := r.bool()
+			tag := r.string()
+
+			fields[i] = types.NewField(fpos, r.currPkg, fname, ftyp, emb)
+			tags[i] = tag
+		}
+		return types.NewStruct(fields, tags)
+
+	case interfaceType:
+		r.currPkg = r.pkg()
+
+		embeddeds := make([]types.Type, r.uint64())
+		for i := range embeddeds {
+			_ = r.pos()
+			embeddeds[i] = r.typ()
+		}
+
+		methods := make([]*types.Func, r.uint64())
+		for i := range methods {
+			mpos := r.pos()
+			mname := r.ident()
+
+			// TODO(mdempsky): Matches bimport.go, but I
+			// don't agree with this.
+			var recv *types.Var
+			if base != nil {
+				recv = types.NewVar(token.NoPos, r.currPkg, "", base)
+			}
+
+			msig := r.signature(recv)
+			methods[i] = types.NewFunc(mpos, r.currPkg, mname, msig)
+		}
+
+		typ := types.NewInterfaceType(methods, embeddeds)
+		r.p.interfaceList = append(r.p.interfaceList, typ)
+		return typ
+	}
+}
+
+func (r *importReader) kind() itag {
+	return itag(r.uint64())
+}
+
+func (r *importReader) signature(recv *types.Var) *types.Signature {
+	params := r.paramList()
+	results := r.paramList()
+	variadic := params.Len() > 0 && r.bool()
+	return types.NewSignature(recv, params, results, variadic)
+}
+
+func (r *importReader) paramList() *types.Tuple {
+	xs := make([]*types.Var, r.uint64())
+	for i := range xs {
+		xs[i] = r.param()
+	}
+	return types.NewTuple(xs...)
+}
+
+func (r *importReader) param() *types.Var {
+	pos := r.pos()
+	name := r.ident()
+	typ := r.typ()
+	return types.NewParam(pos, r.currPkg, name, typ)
+}
+
+func (r *importReader) bool() bool {
+	return r.uint64() != 0
+}
+
+func (r *importReader) int64() int64 {
+	n, err := binary.ReadVarint(&r.declReader)
+	if err != nil {
+		errorf("readVarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) uint64() uint64 {
+	n, err := binary.ReadUvarint(&r.declReader)
+	if err != nil {
+		errorf("readUvarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) byte() byte {
+	x, err := r.declReader.ReadByte()
+	if err != nil {
+		errorf("declReader.ReadByte: %v", err)
+	}
+	return x
+}
diff --git a/src/go/internal/gcimporter/support.go b/src/go/internal/gcimporter/support.go
new file mode 100644
index 0000000..b8bb14d
--- /dev/null
+++ b/src/go/internal/gcimporter/support.go
@@ -0,0 +1,130 @@
+// 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.
+
+// This file implements support functionality for iimport.go.
+
+package gcimporter
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"sync"
+)
+
+func errorf(format string, args ...interface{}) {
+	panic(fmt.Sprintf(format, args...))
+}
+
+// deltaNewFile is a magic line delta offset indicating a new file.
+// We use -64 because it is rare; see issue 20080 and CL 41619.
+// -64 is the smallest int that fits in a single byte as a varint.
+const deltaNewFile = -64
+
+// Synthesize a token.Pos
+type fakeFileSet struct {
+	fset  *token.FileSet
+	files map[string]*token.File
+}
+
+func (s *fakeFileSet) pos(file string, line, column int) token.Pos {
+	// TODO(mdempsky): Make use of column.
+
+	// Since we don't know the set of needed file positions, we
+	// reserve maxlines positions per file.
+	const maxlines = 64 * 1024
+	f := s.files[file]
+	if f == nil {
+		f = s.fset.AddFile(file, -1, maxlines)
+		s.files[file] = f
+		// Allocate the fake linebreak indices on first use.
+		// TODO(adonovan): opt: save ~512KB using a more complex scheme?
+		fakeLinesOnce.Do(func() {
+			fakeLines = make([]int, maxlines)
+			for i := range fakeLines {
+				fakeLines[i] = i
+			}
+		})
+		f.SetLines(fakeLines)
+	}
+
+	if line > maxlines {
+		line = 1
+	}
+
+	// Treat the file as if it contained only newlines
+	// and column=1: use the line number as the offset.
+	return f.Pos(line - 1)
+}
+
+var (
+	fakeLines     []int
+	fakeLinesOnce sync.Once
+)
+
+func chanDir(d int) types.ChanDir {
+	// tag values must match the constants in cmd/compile/internal/gc/go.go
+	switch d {
+	case 1 /* Crecv */ :
+		return types.RecvOnly
+	case 2 /* Csend */ :
+		return types.SendOnly
+	case 3 /* Cboth */ :
+		return types.SendRecv
+	default:
+		errorf("unexpected channel dir %d", d)
+		return 0
+	}
+}
+
+var predeclared = []types.Type{
+	// basic types
+	types.Typ[types.Bool],
+	types.Typ[types.Int],
+	types.Typ[types.Int8],
+	types.Typ[types.Int16],
+	types.Typ[types.Int32],
+	types.Typ[types.Int64],
+	types.Typ[types.Uint],
+	types.Typ[types.Uint8],
+	types.Typ[types.Uint16],
+	types.Typ[types.Uint32],
+	types.Typ[types.Uint64],
+	types.Typ[types.Uintptr],
+	types.Typ[types.Float32],
+	types.Typ[types.Float64],
+	types.Typ[types.Complex64],
+	types.Typ[types.Complex128],
+	types.Typ[types.String],
+
+	// basic type aliases
+	types.Universe.Lookup("byte").Type(),
+	types.Universe.Lookup("rune").Type(),
+
+	// error
+	types.Universe.Lookup("error").Type(),
+
+	// untyped types
+	types.Typ[types.UntypedBool],
+	types.Typ[types.UntypedInt],
+	types.Typ[types.UntypedRune],
+	types.Typ[types.UntypedFloat],
+	types.Typ[types.UntypedComplex],
+	types.Typ[types.UntypedString],
+	types.Typ[types.UntypedNil],
+
+	// package unsafe
+	types.Typ[types.UnsafePointer],
+
+	// invalid type
+	types.Typ[types.Invalid], // only appears in packages with errors
+
+	// used internally by gc; never used by this package or in .a files
+	anyType{},
+}
+
+type anyType struct{}
+
+func (t anyType) Underlying() types.Type { return t }
+func (t anyType) String() string         { return "any" }
diff --git a/src/go/internal/gcimporter/testdata/a.go b/src/go/internal/gcimporter/testdata/a.go
new file mode 100644
index 0000000..56e4292
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/a.go
@@ -0,0 +1,14 @@
+// Copyright 2016 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.
+
+// Input for TestIssue13566
+
+package a
+
+import "encoding/json"
+
+type A struct {
+	a    *A
+	json json.RawMessage
+}
diff --git a/src/go/internal/gcimporter/testdata/b.go b/src/go/internal/gcimporter/testdata/b.go
new file mode 100644
index 0000000..4196678
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/b.go
@@ -0,0 +1,11 @@
+// Copyright 2016 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.
+
+// Input for TestIssue13566
+
+package b
+
+import "./a"
+
+type A a.A
diff --git a/src/go/internal/gcimporter/testdata/exports.go b/src/go/internal/gcimporter/testdata/exports.go
new file mode 100644
index 0000000..8ba3242
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/exports.go
@@ -0,0 +1,88 @@
+// 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
+	V2 float32 = 1.2
+)
+
+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/src/go/internal/gcimporter/testdata/issue15920.go b/src/go/internal/gcimporter/testdata/issue15920.go
new file mode 100644
index 0000000..c70f7d8
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/issue15920.go
@@ -0,0 +1,11 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// The underlying type of Error is the underlying type of error.
+// Make sure we can import this again without problems.
+type Error error
+
+func F() Error { return nil }
diff --git a/src/go/internal/gcimporter/testdata/issue20046.go b/src/go/internal/gcimporter/testdata/issue20046.go
new file mode 100644
index 0000000..c63ee82
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/issue20046.go
@@ -0,0 +1,9 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+var V interface {
+	M()
+}
diff --git a/src/go/internal/gcimporter/testdata/issue25301.go b/src/go/internal/gcimporter/testdata/issue25301.go
new file mode 100644
index 0000000..e3dc98b
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/issue25301.go
@@ -0,0 +1,17 @@
+// Copyright 2018 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 issue25301
+
+type (
+	A = interface {
+		M()
+	}
+	T interface {
+		A
+	}
+	S struct{}
+)
+
+func (S) M() { println("m") }
diff --git a/src/go/internal/gcimporter/testdata/issue25596.go b/src/go/internal/gcimporter/testdata/issue25596.go
new file mode 100644
index 0000000..8923373
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/issue25596.go
@@ -0,0 +1,13 @@
+// Copyright 2018 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 issue25596
+
+type E interface {
+	M() T
+}
+
+type T interface {
+	E
+}
diff --git a/src/go/internal/gcimporter/testdata/p.go b/src/go/internal/gcimporter/testdata/p.go
new file mode 100644
index 0000000..9e2e705
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/p.go
@@ -0,0 +1,13 @@
+// Copyright 2016 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.
+
+// Input for TestIssue15517
+
+package p
+
+const C = 0
+
+var V int
+
+func F() {}
diff --git a/src/go/internal/gcimporter/testdata/versions/test.go b/src/go/internal/gcimporter/testdata/versions/test.go
new file mode 100644
index 0000000..227fc09
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test.go
@@ -0,0 +1,28 @@
+// Copyright 2016 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.
+
+// To create a test case for a new export format version,
+// build this package with the latest compiler and store
+// the resulting .a file appropriately named in the versions
+// directory. The VersionHandling test will pick it up.
+//
+// In the testdata/versions:
+//
+// go build -o test_go1.$X_$Y.a test.go
+//
+// with $X = Go version and $Y = export format version
+// (add 'b' or 'i' to distinguish between binary and
+// indexed format starting with 1.11 as long as both
+// formats are supported).
+//
+// Make sure this source is extended such that it exercises
+// whatever export format change has taken place.
+
+package test
+
+// Any release before and including Go 1.7 didn't encode
+// the package for a blank struct field.
+type BlankField struct {
+	_ int
+}
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.11_0i.a b/src/go/internal/gcimporter/testdata/versions/test_go1.11_0i.a
new file mode 100644
index 0000000..b00fefe
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.11_0i.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.11_6b.a b/src/go/internal/gcimporter/testdata/versions/test_go1.11_6b.a
new file mode 100644
index 0000000..c0a211e
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.11_6b.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.11_999b.a b/src/go/internal/gcimporter/testdata/versions/test_go1.11_999b.a
new file mode 100644
index 0000000..c35d22d
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.11_999b.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.11_999i.a b/src/go/internal/gcimporter/testdata/versions/test_go1.11_999i.a
new file mode 100644
index 0000000..99401d7
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.11_999i.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.7_0.a b/src/go/internal/gcimporter/testdata/versions/test_go1.7_0.a
new file mode 100644
index 0000000..edb6c3f
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.7_0.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.7_1.a b/src/go/internal/gcimporter/testdata/versions/test_go1.7_1.a
new file mode 100644
index 0000000..554d04a
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.7_1.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.8_4.a b/src/go/internal/gcimporter/testdata/versions/test_go1.8_4.a
new file mode 100644
index 0000000..26b8531
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.8_4.a
diff --git a/src/go/internal/gcimporter/testdata/versions/test_go1.8_5.a b/src/go/internal/gcimporter/testdata/versions/test_go1.8_5.a
new file mode 100644
index 0000000..60e52ef
--- /dev/null
+++ b/src/go/internal/gcimporter/testdata/versions/test_go1.8_5.a
diff --git a/src/go/internal/srcimporter/srcimporter.go b/src/go/internal/srcimporter/srcimporter.go
new file mode 100644
index 0000000..e4225eb
--- /dev/null
+++ b/src/go/internal/srcimporter/srcimporter.go
@@ -0,0 +1,265 @@
+// Copyright 2017 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 srcimporter implements importing directly
+// from source files rather than installed packages.
+package srcimporter // import "go/internal/srcimporter"
+
+import (
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"go/types"
+	exec "internal/execabs"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	_ "unsafe" // for go:linkname
+)
+
+// An Importer provides the context for importing packages from source code.
+type Importer struct {
+	ctxt     *build.Context
+	fset     *token.FileSet
+	sizes    types.Sizes
+	packages map[string]*types.Package
+}
+
+// New returns a new Importer for the given context, file set, and map
+// of packages. The context is used to resolve import paths to package paths,
+// and identifying the files belonging to the package. If the context provides
+// non-nil file system functions, they are used instead of the regular package
+// os functions. The file set is used to track position information of package
+// files; and imported packages are added to the packages map.
+func New(ctxt *build.Context, fset *token.FileSet, packages map[string]*types.Package) *Importer {
+	return &Importer{
+		ctxt:     ctxt,
+		fset:     fset,
+		sizes:    types.SizesFor(ctxt.Compiler, ctxt.GOARCH), // uses go/types default if GOARCH not found
+		packages: packages,
+	}
+}
+
+// Importing is a sentinel taking the place in Importer.packages
+// for a package that is in the process of being imported.
+var importing types.Package
+
+// Import(path) is a shortcut for ImportFrom(path, ".", 0).
+func (p *Importer) Import(path string) (*types.Package, error) {
+	return p.ImportFrom(path, ".", 0) // use "." rather than "" (see issue #24441)
+}
+
+// ImportFrom imports the package with the given import path resolved from the given srcDir,
+// adds the new package to the set of packages maintained by the importer, and returns the
+// package. Package path resolution and file system operations are controlled by the context
+// maintained with the importer. The import mode must be zero but is otherwise ignored.
+// Packages that are not comprised entirely of pure Go files may fail to import because the
+// type checker may not be able to determine all exported entities (e.g. due to cgo dependencies).
+func (p *Importer) ImportFrom(path, srcDir string, mode types.ImportMode) (*types.Package, error) {
+	if mode != 0 {
+		panic("non-zero import mode")
+	}
+
+	if abs, err := p.absPath(srcDir); err == nil { // see issue #14282
+		srcDir = abs
+	}
+	bp, err := p.ctxt.Import(path, srcDir, 0)
+	if err != nil {
+		return nil, err // err may be *build.NoGoError - return as is
+	}
+
+	// package unsafe is known to the type checker
+	if bp.ImportPath == "unsafe" {
+		return types.Unsafe, nil
+	}
+
+	// no need to re-import if the package was imported completely before
+	pkg := p.packages[bp.ImportPath]
+	if pkg != nil {
+		if pkg == &importing {
+			return nil, fmt.Errorf("import cycle through package %q", bp.ImportPath)
+		}
+		if !pkg.Complete() {
+			// Package exists but is not complete - we cannot handle this
+			// at the moment since the source importer replaces the package
+			// wholesale rather than augmenting it (see #19337 for details).
+			// Return incomplete package with error (see #16088).
+			return pkg, fmt.Errorf("reimported partially imported package %q", bp.ImportPath)
+		}
+		return pkg, nil
+	}
+
+	p.packages[bp.ImportPath] = &importing
+	defer func() {
+		// clean up in case of error
+		// TODO(gri) Eventually we may want to leave a (possibly empty)
+		// package in the map in all cases (and use that package to
+		// identify cycles). See also issue 16088.
+		if p.packages[bp.ImportPath] == &importing {
+			p.packages[bp.ImportPath] = nil
+		}
+	}()
+
+	var filenames []string
+	filenames = append(filenames, bp.GoFiles...)
+	filenames = append(filenames, bp.CgoFiles...)
+
+	files, err := p.parseFiles(bp.Dir, filenames)
+	if err != nil {
+		return nil, err
+	}
+
+	// type-check package files
+	var firstHardErr error
+	conf := types.Config{
+		IgnoreFuncBodies: true,
+		// continue type-checking after the first error
+		Error: func(err error) {
+			if firstHardErr == nil && !err.(types.Error).Soft {
+				firstHardErr = err
+			}
+		},
+		Importer: p,
+		Sizes:    p.sizes,
+	}
+	if len(bp.CgoFiles) > 0 {
+		if p.ctxt.OpenFile != nil {
+			// cgo, gcc, pkg-config, etc. do not support
+			// build.Context's VFS.
+			conf.FakeImportC = true
+		} else {
+			setUsesCgo(&conf)
+			file, err := p.cgo(bp)
+			if err != nil {
+				return nil, err
+			}
+			files = append(files, file)
+		}
+	}
+
+	pkg, err = conf.Check(bp.ImportPath, p.fset, files, nil)
+	if err != nil {
+		// If there was a hard error it is possibly unsafe
+		// to use the package as it may not be fully populated.
+		// Do not return it (see also #20837, #20855).
+		if firstHardErr != nil {
+			pkg = nil
+			err = firstHardErr // give preference to first hard error over any soft error
+		}
+		return pkg, fmt.Errorf("type-checking package %q failed (%v)", bp.ImportPath, err)
+	}
+	if firstHardErr != nil {
+		// this can only happen if we have a bug in go/types
+		panic("package is not safe yet no error was returned")
+	}
+
+	p.packages[bp.ImportPath] = pkg
+	return pkg, nil
+}
+
+func (p *Importer) parseFiles(dir string, filenames []string) ([]*ast.File, error) {
+	// use build.Context's OpenFile if there is one
+	open := p.ctxt.OpenFile
+	if open == nil {
+		open = func(name string) (io.ReadCloser, error) { return os.Open(name) }
+	}
+
+	files := make([]*ast.File, len(filenames))
+	errors := make([]error, len(filenames))
+
+	var wg sync.WaitGroup
+	wg.Add(len(filenames))
+	for i, filename := range filenames {
+		go func(i int, filepath string) {
+			defer wg.Done()
+			src, err := open(filepath)
+			if err != nil {
+				errors[i] = err // open provides operation and filename in error
+				return
+			}
+			files[i], errors[i] = parser.ParseFile(p.fset, filepath, src, 0)
+			src.Close() // ignore Close error - parsing may have succeeded which is all we need
+		}(i, p.joinPath(dir, filename))
+	}
+	wg.Wait()
+
+	// if there are errors, return the first one for deterministic results
+	for _, err := range errors {
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return files, nil
+}
+
+func (p *Importer) cgo(bp *build.Package) (*ast.File, error) {
+	tmpdir, err := os.MkdirTemp("", "srcimporter")
+	if err != nil {
+		return nil, err
+	}
+	defer os.RemoveAll(tmpdir)
+
+	args := []string{"go", "tool", "cgo", "-objdir", tmpdir}
+	if bp.Goroot {
+		switch bp.ImportPath {
+		case "runtime/cgo":
+			args = append(args, "-import_runtime_cgo=false", "-import_syscall=false")
+		case "runtime/race":
+			args = append(args, "-import_syscall=false")
+		}
+	}
+	args = append(args, "--")
+	args = append(args, strings.Fields(os.Getenv("CGO_CPPFLAGS"))...)
+	args = append(args, bp.CgoCPPFLAGS...)
+	if len(bp.CgoPkgConfig) > 0 {
+		cmd := exec.Command("pkg-config", append([]string{"--cflags"}, bp.CgoPkgConfig...)...)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			return nil, err
+		}
+		args = append(args, strings.Fields(string(out))...)
+	}
+	args = append(args, "-I", tmpdir)
+	args = append(args, strings.Fields(os.Getenv("CGO_CFLAGS"))...)
+	args = append(args, bp.CgoCFLAGS...)
+	args = append(args, bp.CgoFiles...)
+
+	cmd := exec.Command(args[0], args[1:]...)
+	cmd.Dir = bp.Dir
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	return parser.ParseFile(p.fset, filepath.Join(tmpdir, "_cgo_gotypes.go"), nil, 0)
+}
+
+// context-controlled file system operations
+
+func (p *Importer) absPath(path string) (string, error) {
+	// TODO(gri) This should be using p.ctxt.AbsPath which doesn't
+	// exist but probably should. See also issue #14282.
+	return filepath.Abs(path)
+}
+
+func (p *Importer) isAbsPath(path string) bool {
+	if f := p.ctxt.IsAbsPath; f != nil {
+		return f(path)
+	}
+	return filepath.IsAbs(path)
+}
+
+func (p *Importer) joinPath(elem ...string) string {
+	if f := p.ctxt.JoinPath; f != nil {
+		return f(elem...)
+	}
+	return filepath.Join(elem...)
+}
+
+//go:linkname setUsesCgo go/types.srcimporter_setUsesCgo
+func setUsesCgo(conf *types.Config)
diff --git a/src/go/internal/srcimporter/srcimporter_test.go b/src/go/internal/srcimporter/srcimporter_test.go
new file mode 100644
index 0000000..05b12f1
--- /dev/null
+++ b/src/go/internal/srcimporter/srcimporter_test.go
@@ -0,0 +1,254 @@
+// Copyright 2017 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 srcimporter
+
+import (
+	"flag"
+	"go/build"
+	"go/token"
+	"go/types"
+	"internal/testenv"
+	"os"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestMain(m *testing.M) {
+	flag.Parse()
+	if goTool, err := testenv.GoTool(); err == nil {
+		os.Setenv("PATH", filepath.Dir(goTool)+string(os.PathListSeparator)+os.Getenv("PATH"))
+	}
+	os.Exit(m.Run())
+}
+
+const maxTime = 2 * time.Second
+
+var importer = New(&build.Default, token.NewFileSet(), make(map[string]*types.Package))
+
+func doImport(t *testing.T, path, srcDir string) {
+	t0 := time.Now()
+	if _, err := importer.ImportFrom(path, srcDir, 0); err != nil {
+		// don't report an error if there's no buildable Go files
+		if _, nogo := err.(*build.NoGoError); !nogo {
+			t.Errorf("import %q failed (%v)", path, err)
+		}
+		return
+	}
+	t.Logf("import %q: %v", path, time.Since(t0))
+}
+
+// walkDir imports the all the packages with the given path
+// prefix recursively. It returns the number of packages
+// imported and whether importing was aborted because time
+// has passed endTime.
+func walkDir(t *testing.T, path string, endTime time.Time) (int, bool) {
+	if time.Now().After(endTime) {
+		t.Log("testing time used up")
+		return 0, true
+	}
+
+	// ignore fake packages and testdata directories
+	if path == "builtin" || path == "unsafe" || strings.HasSuffix(path, "testdata") {
+		return 0, false
+	}
+
+	list, err := os.ReadDir(filepath.Join(runtime.GOROOT(), "src", path))
+	if err != nil {
+		t.Fatalf("walkDir %s failed (%v)", path, err)
+	}
+
+	nimports := 0
+	hasGoFiles := false
+	for _, f := range list {
+		if f.IsDir() {
+			n, abort := walkDir(t, filepath.Join(path, f.Name()), endTime)
+			nimports += n
+			if abort {
+				return nimports, true
+			}
+		} else if strings.HasSuffix(f.Name(), ".go") {
+			hasGoFiles = true
+		}
+	}
+
+	if hasGoFiles {
+		doImport(t, path, "")
+		nimports++
+	}
+
+	return nimports, false
+}
+
+func TestImportStdLib(t *testing.T) {
+	if !testenv.HasSrc() {
+		t.Skip("no source code available")
+	}
+
+	if testing.Short() && testenv.Builder() == "" {
+		t.Skip("skipping in -short mode")
+	}
+	dt := maxTime
+	nimports, _ := walkDir(t, "", time.Now().Add(dt)) // installed packages
+	t.Logf("tested %d imports", nimports)
+}
+
+var importedObjectTests = []struct {
+	name string
+	want string
+}{
+	{"flag.Bool", "func Bool(name string, value bool, usage string) *bool"},
+	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
+	{"io.ReadWriter", "type ReadWriter interface{Reader; Writer}"}, // go/types.gcCompatibilityMode is off => interface not flattened
+	{"math.Pi", "const Pi untyped float"},
+	{"math.Sin", "func Sin(x float64) float64"},
+	{"math/big.Int", "type Int struct{neg bool; abs nat}"},
+	{"golang.org/x/text/unicode/norm.MaxSegmentSize", "const MaxSegmentSize untyped int"},
+}
+
+func TestImportedTypes(t *testing.T) {
+	if !testenv.HasSrc() {
+		t.Skip("no source code available")
+	}
+
+	for _, test := range importedObjectTests {
+		i := strings.LastIndex(test.name, ".")
+		if i < 0 {
+			t.Fatal("invalid test data format")
+		}
+		importPath := test.name[:i]
+		objName := test.name[i+1:]
+
+		pkg, err := importer.ImportFrom(importPath, ".", 0)
+		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)
+		}
+
+		if named, _ := obj.Type().(*types.Named); named != nil {
+			verifyInterfaceMethodRecvs(t, named, 0)
+		}
+	}
+}
+
+// verifyInterfaceMethodRecvs verifies that method receiver types
+// are named if the methods belong to a named interface type.
+func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
+	// avoid endless recursion in case of an embedding bug that lead to a cycle
+	if level > 10 {
+		t.Errorf("%s: embeds itself", named)
+		return
+	}
+
+	iface, _ := named.Underlying().(*types.Interface)
+	if iface == nil {
+		return // not an interface
+	}
+
+	// check explicitly declared methods
+	for i := 0; i < iface.NumExplicitMethods(); i++ {
+		m := iface.ExplicitMethod(i)
+		recv := m.Type().(*types.Signature).Recv()
+		if recv == nil {
+			t.Errorf("%s: missing receiver type", m)
+			continue
+		}
+		if recv.Type() != named {
+			t.Errorf("%s: got recv type %s; want %s", m, recv.Type(), named)
+		}
+	}
+
+	// check embedded interfaces (they are named, too)
+	for i := 0; i < iface.NumEmbeddeds(); i++ {
+		// embedding of interfaces cannot have cycles; recursion will terminate
+		verifyInterfaceMethodRecvs(t, iface.Embedded(i), level+1)
+	}
+}
+
+func TestReimport(t *testing.T) {
+	if !testenv.HasSrc() {
+		t.Skip("no source code available")
+	}
+
+	// Reimporting a partially imported (incomplete) package is not supported (see issue #19337).
+	// Make sure we recognize the situation and report an error.
+
+	mathPkg := types.NewPackage("math", "math") // incomplete package
+	importer := New(&build.Default, token.NewFileSet(), map[string]*types.Package{mathPkg.Path(): mathPkg})
+	_, err := importer.ImportFrom("math", ".", 0)
+	if err == nil || !strings.HasPrefix(err.Error(), "reimport") {
+		t.Errorf("got %v; want reimport error", err)
+	}
+}
+
+func TestIssue20855(t *testing.T) {
+	if !testenv.HasSrc() {
+		t.Skip("no source code available")
+	}
+
+	pkg, err := importer.ImportFrom("go/internal/srcimporter/testdata/issue20855", ".", 0)
+	if err == nil || !strings.Contains(err.Error(), "missing function body") {
+		t.Fatalf("got unexpected or no error: %v", err)
+	}
+	if pkg == nil {
+		t.Error("got no package despite no hard errors")
+	}
+}
+
+func testImportPath(t *testing.T, pkgPath string) {
+	if !testenv.HasSrc() {
+		t.Skip("no source code available")
+	}
+
+	pkgName := path.Base(pkgPath)
+
+	pkg, err := importer.Import(pkgPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if pkg.Name() != pkgName {
+		t.Errorf("got %q; want %q", pkg.Name(), pkgName)
+	}
+
+	if pkg.Path() != pkgPath {
+		t.Errorf("got %q; want %q", pkg.Path(), pkgPath)
+	}
+}
+
+// TestIssue23092 tests relative imports.
+func TestIssue23092(t *testing.T) {
+	testImportPath(t, "./testdata/issue23092")
+}
+
+// TestIssue24392 tests imports against a path containing 'testdata'.
+func TestIssue24392(t *testing.T) {
+	testImportPath(t, "go/internal/srcimporter/testdata/issue24392")
+}
+
+func TestCgo(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+	testenv.MustHaveCGO(t)
+
+	importer := New(&build.Default, token.NewFileSet(), make(map[string]*types.Package))
+	_, err := importer.ImportFrom("./misc/cgo/test", runtime.GOROOT(), 0)
+	if err != nil {
+		t.Fatalf("Import failed: %v", err)
+	}
+}
diff --git a/src/go/internal/srcimporter/testdata/issue20855/issue20855.go b/src/go/internal/srcimporter/testdata/issue20855/issue20855.go
new file mode 100644
index 0000000..d55448b
--- /dev/null
+++ b/src/go/internal/srcimporter/testdata/issue20855/issue20855.go
@@ -0,0 +1,7 @@
+// Copyright 2017 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 issue20855
+
+func init() // "missing function body" is a soft error
diff --git a/src/go/internal/srcimporter/testdata/issue23092/issue23092.go b/src/go/internal/srcimporter/testdata/issue23092/issue23092.go
new file mode 100644
index 0000000..608698b
--- /dev/null
+++ b/src/go/internal/srcimporter/testdata/issue23092/issue23092.go
@@ -0,0 +1,5 @@
+// Copyright 2018 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 issue23092
diff --git a/src/go/internal/srcimporter/testdata/issue24392/issue24392.go b/src/go/internal/srcimporter/testdata/issue24392/issue24392.go
new file mode 100644
index 0000000..8ad5221
--- /dev/null
+++ b/src/go/internal/srcimporter/testdata/issue24392/issue24392.go
@@ -0,0 +1,5 @@
+// Copyright 2018 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 issue24392
diff --git a/src/go/internal/typeparams/common.go b/src/go/internal/typeparams/common.go
new file mode 100644
index 0000000..47b8f7c
--- /dev/null
+++ b/src/go/internal/typeparams/common.go
@@ -0,0 +1,13 @@
+// Copyright 2021 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 typeparams provides functions to work with type parameter data
+// stored in the AST, while these AST changes are guarded by a build
+// constraint.
+package typeparams
+
+// DisallowParsing is the numeric value of a parsing mode that disallows type
+// parameters. This only matters if the typeparams experiment is active, and
+// may be used for running tests that disallow generics.
+const DisallowParsing = 1 << 30
diff --git a/src/go/internal/typeparams/notypeparams.go b/src/go/internal/typeparams/notypeparams.go
new file mode 100644
index 0000000..2ceafaa
--- /dev/null
+++ b/src/go/internal/typeparams/notypeparams.go
@@ -0,0 +1,40 @@
+// Copyright 2021 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.
+
+//go:build !typeparams
+// +build !typeparams
+
+package typeparams
+
+import (
+	"go/ast"
+)
+
+const Enabled = false
+
+func PackExpr(list []ast.Expr) ast.Expr {
+	switch len(list) {
+	case 1:
+		return list[0]
+	default:
+		// The parser should not attempt to pack multiple expressions into an
+		// IndexExpr if type params are disabled.
+		panic("multiple index expressions are unsupported without type params")
+	}
+}
+
+func UnpackExpr(expr ast.Expr) []ast.Expr {
+	return []ast.Expr{expr}
+}
+
+func IsListExpr(n ast.Node) bool {
+	return false
+}
+
+func Get(ast.Node) *ast.FieldList {
+	return nil
+}
+
+func Set(node ast.Node, params *ast.FieldList) {
+}
diff --git a/src/go/internal/typeparams/typeparams.go b/src/go/internal/typeparams/typeparams.go
new file mode 100644
index 0000000..871e95d
--- /dev/null
+++ b/src/go/internal/typeparams/typeparams.go
@@ -0,0 +1,69 @@
+// Copyright 2021 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.
+
+//go:build typeparams
+// +build typeparams
+
+package typeparams
+
+import (
+	"fmt"
+	"go/ast"
+)
+
+const Enabled = true
+
+func PackExpr(list []ast.Expr) ast.Expr {
+	switch len(list) {
+	case 0:
+		// Return an empty ListExpr here, rather than nil, as IndexExpr.Index must
+		// never be nil.
+		// TODO(rFindley) would a BadExpr be more appropriate here?
+		return &ast.ListExpr{}
+	case 1:
+		return list[0]
+	default:
+		return &ast.ListExpr{ElemList: list}
+	}
+}
+
+// TODO(gri) Should find a more efficient solution that doesn't
+//           require introduction of a new slice for simple
+//           expressions.
+func UnpackExpr(x ast.Expr) []ast.Expr {
+	if x, _ := x.(*ast.ListExpr); x != nil {
+		return x.ElemList
+	}
+	if x != nil {
+		return []ast.Expr{x}
+	}
+	return nil
+}
+
+func IsListExpr(n ast.Node) bool {
+	_, ok := n.(*ast.ListExpr)
+	return ok
+}
+
+func Get(n ast.Node) *ast.FieldList {
+	switch n := n.(type) {
+	case *ast.TypeSpec:
+		return n.TParams
+	case *ast.FuncType:
+		return n.TParams
+	default:
+		panic(fmt.Sprintf("node type %T has no type parameters", n))
+	}
+}
+
+func Set(n ast.Node, params *ast.FieldList) {
+	switch n := n.(type) {
+	case *ast.TypeSpec:
+		n.TParams = params
+	case *ast.FuncType:
+		n.TParams = params
+	default:
+		panic(fmt.Sprintf("node type %T has no type parameters", n))
+	}
+}