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Source file src/go/build/deps_test.go

Documentation: go/build

  // Copyright 2012 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  // This file exercises the import parser but also checks that
  // some low-level packages do not have new dependencies added.
  package build
  import (
  // pkgDeps defines the expected dependencies between packages in
  // the Go source tree. It is a statement of policy.
  // Changes should not be made to this map without prior discussion.
  // The map contains two kinds of entries:
  // 1) Lower-case keys are standard import paths and list the
  // allowed imports in that package.
  // 2) Upper-case keys define aliases for package sets, which can then
  // be used as dependencies by other rules.
  var pkgDeps = map[string][]string{
  	// L0 is the lowest level, core, nearly unavoidable packages.
  	"errors":                  {},
  	"io":                      {"errors", "sync", "sync/atomic"},
  	"runtime":                 {"unsafe", "runtime/internal/atomic", "runtime/internal/sys", "internal/cpu", "internal/bytealg"},
  	"runtime/internal/sys":    {},
  	"runtime/internal/atomic": {"unsafe", "runtime/internal/sys"},
  	"internal/race":           {"runtime", "unsafe"},
  	"sync":                    {"internal/race", "runtime", "sync/atomic", "unsafe"},
  	"sync/atomic":             {"unsafe"},
  	"unsafe":                  {},
  	"internal/cpu":            {},
  	"internal/bytealg":        {"unsafe", "internal/cpu"},
  	"L0": {
  	// L1 adds simple functions and strings processing,
  	// but not Unicode tables.
  	"math":          {"internal/cpu", "unsafe"},
  	"math/bits":     {},
  	"math/cmplx":    {"math"},
  	"math/rand":     {"L0", "math"},
  	"strconv":       {"L0", "unicode/utf8", "math", "math/bits"},
  	"unicode/utf16": {},
  	"unicode/utf8":  {},
  	"L1": {
  	// L2 adds Unicode and strings processing.
  	"bufio":   {"L0", "unicode/utf8", "bytes"},
  	"bytes":   {"L0", "unicode", "unicode/utf8"},
  	"path":    {"L0", "unicode/utf8", "strings"},
  	"strings": {"L0", "unicode", "unicode/utf8"},
  	"unicode": {},
  	"L2": {
  	// L3 adds reflection and some basic utility packages
  	// and interface definitions, but nothing that makes
  	// system calls.
  	"crypto":                 {"L2", "hash"}, // interfaces
  	"crypto/cipher":          {"L2", "crypto/subtle", "crypto/internal/subtle"},
  	"crypto/internal/subtle": {"unsafe", "reflect"}, // reflect behind a appengine tag
  	"crypto/subtle":          {},
  	"encoding/base32":        {"L2"},
  	"encoding/base64":        {"L2", "encoding/binary"},
  	"encoding/binary":        {"L2", "reflect"},
  	"hash":                   {"L2"}, // interfaces
  	"hash/adler32":           {"L2", "hash"},
  	"hash/crc32":             {"L2", "hash"},
  	"hash/crc64":             {"L2", "hash"},
  	"hash/fnv":               {"L2", "hash"},
  	"image":                  {"L2", "image/color"}, // interfaces
  	"image/color":            {"L2"},                // interfaces
  	"image/color/palette":    {"L2", "image/color"},
  	"reflect":                {"L2"},
  	"sort":                   {"reflect"},
  	"L3": {
  	// End of linear dependency definitions.
  	// Operating system access.
  	"syscall":                           {"L0", "internal/race", "internal/syscall/windows/sysdll", "syscall/js", "unicode/utf16"},
  	"syscall/js":                        {"L0"},
  	"internal/syscall/unix":             {"L0", "syscall"},
  	"internal/syscall/windows":          {"L0", "syscall", "internal/syscall/windows/sysdll"},
  	"internal/syscall/windows/registry": {"L0", "syscall", "internal/syscall/windows/sysdll", "unicode/utf16"},
  	"time": {
  		// "L0" without the "io" package:
  		// Other time dependencies:
  	"internal/poll":    {"L0", "internal/race", "syscall", "time", "unicode/utf16", "unicode/utf8", "internal/syscall/windows"},
  	"internal/testlog": {"L0"},
  	"os":               {"L1", "os", "syscall", "time", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/testlog"},
  	"path/filepath":    {"L2", "os", "syscall", "internal/syscall/windows"},
  	"io/ioutil":        {"L2", "os", "path/filepath", "time"},
  	"os/exec":          {"L2", "os", "context", "path/filepath", "syscall"},
  	"os/signal":        {"L2", "os", "syscall"},
  	// OS enables basic operating system functionality,
  	// but not direct use of package syscall, nor os/signal.
  	"OS": {
  	// Formatted I/O: few dependencies (L1) but we must add reflect.
  	"fmt": {"L1", "os", "reflect"},
  	"log": {"L1", "os", "fmt", "time"},
  	// Packages used by testing must be low-level (L2+fmt).
  	"regexp":         {"L2", "regexp/syntax"},
  	"regexp/syntax":  {"L2"},
  	"runtime/debug":  {"L2", "fmt", "io/ioutil", "os", "time"},
  	"runtime/pprof":  {"L2", "compress/gzip", "context", "encoding/binary", "fmt", "io/ioutil", "os", "text/tabwriter", "time"},
  	"runtime/trace":  {"L0", "context", "fmt"},
  	"text/tabwriter": {"L2"},
  	"testing":          {"L2", "flag", "fmt", "internal/race", "os", "runtime/debug", "runtime/pprof", "runtime/trace", "time"},
  	"testing/iotest":   {"L2", "log"},
  	"testing/quick":    {"L2", "flag", "fmt", "reflect", "time"},
  	"internal/testenv": {"L2", "OS", "flag", "testing", "syscall"},
  	// L4 is defined as L3+fmt+log+time, because in general once
  	// you're using L3 packages, use of fmt, log, or time is not a big deal.
  	"L4": {
  	// Go parser.
  	"go/ast":     {"L4", "OS", "go/scanner", "go/token"},
  	"go/doc":     {"L4", "go/ast", "go/token", "regexp", "text/template"},
  	"go/parser":  {"L4", "OS", "go/ast", "go/scanner", "go/token"},
  	"go/printer": {"L4", "OS", "go/ast", "go/scanner", "go/token", "text/tabwriter"},
  	"go/scanner": {"L4", "OS", "go/token"},
  	"go/token":   {"L4"},
  	"GOPARSER": {
  	"go/format":       {"L4", "GOPARSER", "internal/format"},
  	"internal/format": {"L4", "GOPARSER"},
  	// Go type checking.
  	"go/constant":               {"L4", "go/token", "math/big"},
  	"go/importer":               {"L4", "go/build", "go/internal/gccgoimporter", "go/internal/gcimporter", "go/internal/srcimporter", "go/token", "go/types"},
  	"go/internal/gcimporter":    {"L4", "OS", "go/build", "go/constant", "go/token", "go/types", "text/scanner"},
  	"go/internal/gccgoimporter": {"L4", "OS", "debug/elf", "go/constant", "go/token", "go/types", "text/scanner"},
  	"go/internal/srcimporter":   {"L4", "OS", "fmt", "go/ast", "go/build", "go/parser", "go/token", "go/types", "path/filepath"},
  	"go/types":                  {"L4", "GOPARSER", "container/heap", "go/constant"},
  	// One of a kind.
  	"archive/tar":              {"L4", "OS", "syscall", "os/user"},
  	"archive/zip":              {"L4", "OS", "compress/flate"},
  	"container/heap":           {"sort"},
  	"compress/bzip2":           {"L4"},
  	"compress/flate":           {"L4"},
  	"compress/gzip":            {"L4", "compress/flate"},
  	"compress/lzw":             {"L4"},
  	"compress/zlib":            {"L4", "compress/flate"},
  	"context":                  {"errors", "fmt", "reflect", "sync", "time"},
  	"database/sql":             {"L4", "container/list", "context", "database/sql/driver", "database/sql/internal"},
  	"database/sql/driver":      {"L4", "context", "time", "database/sql/internal"},
  	"debug/dwarf":              {"L4"},
  	"debug/elf":                {"L4", "OS", "debug/dwarf", "compress/zlib"},
  	"debug/gosym":              {"L4"},
  	"debug/macho":              {"L4", "OS", "debug/dwarf", "compress/zlib"},
  	"debug/pe":                 {"L4", "OS", "debug/dwarf", "compress/zlib"},
  	"debug/plan9obj":           {"L4", "OS"},
  	"encoding":                 {"L4"},
  	"encoding/ascii85":         {"L4"},
  	"encoding/asn1":            {"L4", "math/big"},
  	"encoding/csv":             {"L4"},
  	"encoding/gob":             {"L4", "OS", "encoding"},
  	"encoding/hex":             {"L4"},
  	"encoding/json":            {"L4", "encoding"},
  	"encoding/pem":             {"L4"},
  	"encoding/xml":             {"L4", "encoding"},
  	"flag":                     {"L4", "OS"},
  	"go/build":                 {"L4", "OS", "GOPARSER"},
  	"html":                     {"L4"},
  	"image/draw":               {"L4", "image/internal/imageutil"},
  	"image/gif":                {"L4", "compress/lzw", "image/color/palette", "image/draw"},
  	"image/internal/imageutil": {"L4"},
  	"image/jpeg":               {"L4", "image/internal/imageutil"},
  	"image/png":                {"L4", "compress/zlib"},
  	"index/suffixarray":        {"L4", "regexp"},
  	"internal/singleflight":    {"sync"},
  	"internal/trace":           {"L4", "OS"},
  	"math/big":                 {"L4"},
  	"mime":                     {"L4", "OS", "syscall", "internal/syscall/windows/registry"},
  	"mime/quotedprintable":     {"L4"},
  	"net/internal/socktest":    {"L4", "OS", "syscall", "internal/syscall/windows"},
  	"net/url":                  {"L4"},
  	"plugin":                   {"L0", "OS", "CGO"},
  	"runtime/pprof/internal/profile": {"L4", "OS", "compress/gzip", "regexp"},
  	"testing/internal/testdeps":      {"L4", "internal/testlog", "runtime/pprof", "regexp"},
  	"text/scanner":                   {"L4", "OS"},
  	"text/template/parse":            {"L4"},
  	"html/template": {
  		"L4", "OS", "encoding/json", "html", "text/template",
  	"text/template": {
  		"L4", "OS", "net/url", "text/template/parse",
  	// Cgo.
  	// If you add a dependency on CGO, you must add the package to
  	// cgoPackages in cmd/dist/test.go.
  	"runtime/cgo": {"L0", "C"},
  	"CGO":         {"C", "runtime/cgo"},
  	// Fake entry to satisfy the pseudo-import "C"
  	// that shows up in programs that use cgo.
  	"C": {},
  	// Race detector/MSan uses cgo.
  	"runtime/race": {"C"},
  	"runtime/msan": {"C"},
  	// Plan 9 alone needs io/ioutil and os.
  	"os/user": {"L4", "CGO", "io/ioutil", "os", "syscall", "internal/syscall/windows", "internal/syscall/windows/registry"},
  	// Internal package used only for testing.
  	"os/signal/internal/pty": {"CGO", "fmt", "os", "syscall"},
  	// Basic networking.
  	// Because net must be used by any package that wants to
  	// do networking portably, it must have a small dependency set: just L0+basic os.
  	"net": {
  		"L0", "CGO",
  		"context", "math/rand", "os", "reflect", "sort", "syscall", "time",
  		"internal/nettrace", "internal/poll",
  		"internal/syscall/windows", "internal/singleflight", "internal/race",
  		"golang_org/x/net/dns/dnsmessage", "golang_org/x/net/lif", "golang_org/x/net/route",
  	// NET enables use of basic network-related packages.
  	"NET": {
  	// Uses of networking.
  	"log/syslog":    {"L4", "OS", "net"},
  	"net/mail":      {"L4", "NET", "OS", "mime"},
  	"net/textproto": {"L4", "OS", "net"},
  	// Core crypto.
  	"crypto/aes":               {"L3"},
  	"crypto/des":               {"L3"},
  	"crypto/hmac":              {"L3"},
  	"crypto/internal/randutil": {"io", "sync"},
  	"crypto/md5":               {"L3"},
  	"crypto/rc4":               {"L3"},
  	"crypto/sha1":              {"L3"},
  	"crypto/sha256":            {"L3"},
  	"crypto/sha512":            {"L3"},
  	"CRYPTO": {
  	// Random byte, number generation.
  	// This would be part of core crypto except that it imports
  	// math/big, which imports fmt.
  	"crypto/rand": {"L4", "CRYPTO", "OS", "math/big", "syscall", "syscall/js", "internal/syscall/unix"},
  	// Mathematical crypto: dependencies on fmt (L4) and math/big.
  	// We could avoid some of the fmt, but math/big imports fmt anyway.
  	"crypto/dsa":      {"L4", "CRYPTO", "math/big"},
  	"crypto/ecdsa":    {"L4", "CRYPTO", "crypto/elliptic", "math/big", "encoding/asn1"},
  	"crypto/elliptic": {"L4", "CRYPTO", "math/big"},
  	"crypto/rsa":      {"L4", "CRYPTO", "crypto/rand", "math/big"},
  	// SSL/TLS.
  	"crypto/tls": {
  		"L4", "CRYPTO-MATH", "OS",
  		"container/list", "crypto/x509", "encoding/pem", "net", "syscall",
  	"crypto/x509": {
  		"L4", "CRYPTO-MATH", "OS", "CGO",
  		"crypto/x509/pkix", "encoding/pem", "encoding/hex", "net", "os/user", "syscall", "net/url",
  		"golang_org/x/crypto/cryptobyte", "golang_org/x/crypto/cryptobyte/asn1",
  	"crypto/x509/pkix": {"L4", "CRYPTO-MATH", "encoding/hex"},
  	// Simple net+crypto-aware packages.
  	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto", "mime/quotedprintable"},
  	"net/smtp":       {"L4", "CRYPTO", "NET", "crypto/tls"},
  	// HTTP, kingpin of dependencies.
  	"net/http": {
  		"L4", "NET", "OS",
  	"net/http/internal":  {"L4"},
  	"net/http/httptrace": {"context", "crypto/tls", "internal/nettrace", "net", "net/textproto", "reflect", "time"},
  	// HTTP-using packages.
  	"expvar":             {"L4", "OS", "encoding/json", "net/http"},
  	"net/http/cgi":       {"L4", "NET", "OS", "crypto/tls", "net/http", "regexp"},
  	"net/http/cookiejar": {"L4", "NET", "net/http"},
  	"net/http/fcgi":      {"L4", "NET", "OS", "context", "net/http", "net/http/cgi"},
  	"net/http/httptest": {
  		"L4", "NET", "OS", "crypto/tls", "flag", "net/http", "net/http/internal", "crypto/x509",
  	"net/http/httputil": {"L4", "NET", "OS", "context", "net/http", "net/http/internal"},
  	"net/http/pprof":    {"L4", "OS", "html/template", "net/http", "runtime/pprof", "runtime/trace"},
  	"net/rpc":           {"L4", "NET", "encoding/gob", "html/template", "net/http"},
  	"net/rpc/jsonrpc":   {"L4", "NET", "encoding/json", "net/rpc"},
  // isMacro reports whether p is a package dependency macro
  // (uppercase name).
  func isMacro(p string) bool {
  	return 'A' <= p[0] && p[0] <= 'Z'
  func allowed(pkg string) map[string]bool {
  	m := map[string]bool{}
  	var allow func(string)
  	allow = func(p string) {
  		if m[p] {
  		m[p] = true // set even for macros, to avoid loop on cycle
  		// Upper-case names are macro-expanded.
  		if isMacro(p) {
  			for _, pp := range pkgDeps[p] {
  	for _, pp := range pkgDeps[pkg] {
  	return m
  // listStdPkgs returns the same list of packages as "go list std".
  func listStdPkgs(goroot string) ([]string, error) {
  	// Based on cmd/go's matchPackages function.
  	var pkgs []string
  	src := filepath.Join(goroot, "src") + string(filepath.Separator)
  	walkFn := func(path string, fi os.FileInfo, err error) error {
  		if err != nil || !fi.IsDir() || path == src {
  			return nil
  		base := filepath.Base(path)
  		if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
  			return filepath.SkipDir
  		name := filepath.ToSlash(path[len(src):])
  		if name == "builtin" || name == "cmd" || strings.Contains(name, "golang_org") {
  			return filepath.SkipDir
  		pkgs = append(pkgs, name)
  		return nil
  	if err := filepath.Walk(src, walkFn); err != nil {
  		return nil, err
  	return pkgs, nil
  func TestDependencies(t *testing.T) {
  	iOS := runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64")
  	if runtime.GOOS == "nacl" || iOS {
  		// Tests run in a limited file system and we do not
  		// provide access to every source file.
  		t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
  	ctxt := Default
  	all, err := listStdPkgs(ctxt.GOROOT)
  	if err != nil {
  	for _, pkg := range all {
  		imports, err := findImports(pkg)
  		if err != nil {
  		ok := allowed(pkg)
  		var bad []string
  		for _, imp := range imports {
  			if !ok[imp] {
  				bad = append(bad, imp)
  		if bad != nil {
  			t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
  var buildIgnore = []byte("\n// +build ignore")
  func findImports(pkg string) ([]string, error) {
  	dir := filepath.Join(Default.GOROOT, "src", pkg)
  	files, err := ioutil.ReadDir(dir)
  	if err != nil {
  		return nil, err
  	var imports []string
  	var haveImport = map[string]bool{}
  	for _, file := range files {
  		name := file.Name()
  		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
  		f, err := os.Open(filepath.Join(dir, name))
  		if err != nil {
  			return nil, err
  		var imp []string
  		data, err := readImports(f, false, &imp)
  		if err != nil {
  			return nil, fmt.Errorf("reading %v: %v", name, err)
  		if bytes.Contains(data, buildIgnore) {
  		for _, quoted := range imp {
  			path, err := strconv.Unquote(quoted)
  			if err != nil {
  			if !haveImport[path] {
  				haveImport[path] = true
  				imports = append(imports, path)
  	return imports, nil

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