1 files changed, 774 insertions, 0 deletions
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
new file mode 100644
index 0000000..1ec6ee7
--- /dev/null
+++ b/src/go/build/deps_test.go
@@ -0,0 +1,774 @@
+// Copyright 2022 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 (
+	"bytes"
+	"fmt"
+	"go/token"
+	"internal/dag"
+	"internal/testenv"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+	"sort"
+	"strings"
+	"testing"
+)
+
+// depsRules defines the expected dependencies between packages in
+// the Go source tree. It is a statement of policy.
+//
+// DO NOT CHANGE THIS DATA TO FIX BUILDS.
+// Existing packages should not have their constraints relaxed
+// without prior discussion.
+// Negative assertions should almost never be removed.
+//
+// "a < b" means package b can import package a.
+//
+// See `go doc internal/dag' for the full syntax.
+//
+// All-caps names are pseudo-names for specific points
+// in the dependency lattice.
+var depsRules = `
+	# No dependencies allowed for any of these packages.
+	NONE
+	< constraints, container/list, container/ring,
+	  internal/cfg, internal/coverage, internal/coverage/rtcov,
+	  internal/coverage/uleb128, internal/coverage/calloc,
+	  internal/cpu, internal/goarch,
+	  internal/goexperiment, internal/goos,
+	  internal/goversion, internal/nettrace, internal/platform,
+	  unicode/utf8, unicode/utf16, unicode,
+	  unsafe;
+
+	# These packages depend only on internal/goarch and unsafe.
+	internal/goarch, unsafe
+	< internal/abi;
+
+	# RUNTIME is the core runtime group of packages, all of them very light-weight.
+	internal/abi, internal/cpu, internal/goarch,
+	internal/coverage/rtcov, internal/goexperiment,
+	internal/goos, unsafe
+	< internal/bytealg
+	< internal/itoa
+	< internal/unsafeheader
+	< runtime/internal/sys
+	< runtime/internal/syscall
+	< runtime/internal/atomic
+	< runtime/internal/math
+	< runtime
+	< sync/atomic
+	< internal/race
+	< sync
+	< internal/godebug
+	< internal/reflectlite
+	< errors
+	< internal/oserror, math/bits
+	< RUNTIME;
+
+	RUNTIME
+	< sort
+	< container/heap;
+
+	RUNTIME
+	< io;
+
+	RUNTIME
+	< arena;
+
+	syscall !< io;
+	reflect !< sort;
+
+	RUNTIME, unicode/utf8
+	< path;
+
+	unicode !< path;
+
+	# SYSCALL is RUNTIME plus the packages necessary for basic system calls.
+	RUNTIME, unicode/utf8, unicode/utf16
+	< internal/syscall/windows/sysdll, syscall/js
+	< syscall
+	< internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
+	< internal/syscall/execenv
+	< SYSCALL;
+
+	# TIME is SYSCALL plus the core packages about time, including context.
+	SYSCALL
+	< time/tzdata
+	< time
+	< context
+	< TIME;
+
+	TIME, io, path, sort
+	< io/fs;
+
+	# MATH is RUNTIME plus the basic math packages.
+	RUNTIME
+	< math
+	< MATH;
+
+	unicode !< math;
+
+	MATH
+	< math/cmplx;
+
+	MATH
+	< math/rand;
+
+	MATH
+	< runtime/metrics;
+
+	MATH, unicode/utf8
+	< strconv;
+
+	unicode !< strconv;
+
+	# STR is basic string and buffer manipulation.
+	RUNTIME, io, unicode/utf8, unicode/utf16, unicode
+	< bytes, strings
+	< bufio;
+
+	bufio, path, strconv
+	< STR;
+
+	# OS is basic OS access, including helpers (path/filepath, os/exec, etc).
+	# OS includes string routines, but those must be layered above package os.
+	# OS does not include reflection.
+	io/fs
+	< internal/testlog
+	< internal/poll
+	< internal/safefilepath
+	< os
+	< os/signal;
+
+	io/fs
+	< embed;
+
+	unicode, fmt !< net, os, os/signal;
+
+	os/signal, internal/safefilepath, STR
+	< path/filepath
+	< io/ioutil;
+
+	path/filepath, internal/godebug < os/exec;
+
+	io/ioutil, os/exec, os/signal
+	< OS;
+
+	reflect !< OS;
+
+	OS
+	< golang.org/x/sys/cpu;
+
+	# FMT is OS (which includes string routines) plus reflect and fmt.
+	# It does not include package log, which should be avoided in core packages.
+	arena, strconv, unicode
+	< reflect;
+
+	os, reflect
+	< internal/fmtsort
+	< fmt;
+
+	OS, fmt
+	< FMT;
+
+	log !< FMT;
+
+	# Misc packages needing only FMT.
+	FMT
+	< html,
+	  internal/dag,
+	  internal/goroot,
+	  internal/types/errors,
+	  mime/quotedprintable,
+	  net/internal/socktest,
+	  net/url,
+	  runtime/trace,
+	  text/scanner,
+	  text/tabwriter;
+
+	io, reflect
+	< internal/saferio;
+
+	# encodings
+	# core ones do not use fmt.
+	io, strconv
+	< encoding;
+
+	encoding, reflect
+	< encoding/binary
+	< encoding/base32, encoding/base64;
+
+	FMT, encoding < flag;
+
+	fmt !< encoding/base32, encoding/base64;
+
+	FMT, encoding/base32, encoding/base64, internal/saferio
+	< encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
+	  encoding/json, encoding/pem, encoding/xml, mime;
+
+	# hashes
+	io
+	< hash
+	< hash/adler32, hash/crc32, hash/crc64, hash/fnv, hash/maphash;
+
+	# math/big
+	FMT, encoding/binary, math/rand
+	< math/big;
+
+	# compression
+	FMT, encoding/binary, hash/adler32, hash/crc32
+	< compress/bzip2, compress/flate, compress/lzw
+	< archive/zip, compress/gzip, compress/zlib;
+
+	# templates
+	FMT
+	< text/template/parse;
+
+	net/url, text/template/parse
+	< text/template
+	< internal/lazytemplate;
+
+	# regexp
+	FMT
+	< regexp/syntax
+	< regexp
+	< internal/lazyregexp;
+
+	encoding/json, html, text/template, regexp
+	< html/template;
+
+	# suffix array
+	encoding/binary, regexp
+	< index/suffixarray;
+
+	# executable parsing
+	FMT, encoding/binary, compress/zlib, internal/saferio
+	< runtime/debug
+	< debug/dwarf
+	< debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
+	< debug/buildinfo
+	< DEBUG;
+
+	# go parser and friends.
+	FMT
+	< go/token
+	< go/scanner
+	< go/ast
+	< go/internal/typeparams
+	< go/parser;
+
+	FMT
+	< go/build/constraint, go/doc/comment;
+
+	go/build/constraint, go/doc/comment, go/parser, text/tabwriter
+	< go/printer
+	< go/format;
+
+	go/doc/comment, go/parser, internal/lazyregexp, text/template
+	< go/doc;
+
+	math/big, go/token
+	< go/constant;
+
+	container/heap, go/constant, go/parser, internal/types/errors, regexp
+	< go/types;
+
+	FMT, internal/goexperiment
+	< internal/buildcfg;
+
+	go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion
+	< go/build;
+
+	# databases
+	FMT
+	< database/sql/internal
+	< database/sql/driver
+	< database/sql;
+
+	# images
+	FMT, compress/lzw, compress/zlib
+	< image/color
+	< image, image/color/palette
+	< image/internal/imageutil
+	< image/draw
+	< image/gif, image/jpeg, image/png;
+
+	# cgo, delayed as long as possible.
+	# If you add a dependency on CGO, you must add the package
+	# to cgoPackages in cmd/dist/test.go as well.
+	RUNTIME
+	< C
+	< runtime/cgo
+	< CGO
+	< runtime/msan, runtime/asan;
+
+	# runtime/race
+	NONE < runtime/race/internal/amd64v1;
+	NONE < runtime/race/internal/amd64v3;
+	CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
+
+	# Bulk of the standard library must not use cgo.
+	# The prohibition stops at net and os/user.
+	C !< fmt, go/types, CRYPTO-MATH;
+
+	CGO, OS
+	< plugin;
+
+	CGO, FMT
+	< os/user
+	< archive/tar;
+
+	sync
+	< internal/singleflight;
+
+	os
+	< golang.org/x/net/dns/dnsmessage,
+	  golang.org/x/net/lif,
+	  golang.org/x/net/route;
+
+	os, runtime, strconv, sync, unsafe,
+	internal/godebug
+	< internal/intern;
+
+	internal/bytealg, internal/intern, internal/itoa, math/bits, sort, strconv
+	< net/netip;
+
+	# net is unavoidable when doing any networking,
+	# so large dependencies must be kept out.
+	# This is a long-looking list but most of these
+	# are small with few dependencies.
+	CGO,
+	golang.org/x/net/dns/dnsmessage,
+	golang.org/x/net/lif,
+	golang.org/x/net/route,
+	internal/godebug,
+	internal/nettrace,
+	internal/poll,
+	internal/singleflight,
+	internal/race,
+	net/netip,
+	os
+	< net;
+
+	fmt, unicode !< net;
+	math/rand !< net; # net uses runtime instead
+
+	# NET is net plus net-helper packages.
+	FMT, net
+	< net/textproto;
+
+	mime, net/textproto, net/url
+	< NET;
+
+	# logging - most packages should not import; http and up is allowed
+	FMT
+	< log;
+
+	log !< crypto/tls, database/sql, go/importer, testing;
+
+	FMT, log, net
+	< log/syslog;
+
+	NET, log
+	< net/mail;
+
+	NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
+	sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
+	crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
+
+	# CRYPTO is core crypto algorithms - no cgo, fmt, net.
+	# Unfortunately, stuck with reflect via encoding/binary.
+	crypto/internal/boring/sig,
+	crypto/internal/boring/syso,
+	encoding/binary,
+	golang.org/x/sys/cpu,
+	hash, embed
+	< crypto
+	< crypto/subtle
+	< crypto/internal/alias
+	< crypto/cipher;
+
+	crypto/cipher,
+	crypto/internal/boring/bcache
+	< crypto/internal/boring
+	< crypto/boring;
+
+	crypto/internal/alias
+	< crypto/internal/randutil
+	< crypto/internal/nistec/fiat
+	< crypto/internal/nistec
+	< crypto/internal/edwards25519/field
+	< crypto/internal/edwards25519;
+
+	crypto/boring
+	< crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
+	  crypto/sha1, crypto/sha256, crypto/sha512;
+
+	crypto/boring, crypto/internal/edwards25519/field
+	< crypto/ecdh;
+
+	crypto/aes,
+	crypto/des,
+	crypto/ecdh,
+	crypto/hmac,
+	crypto/internal/edwards25519,
+	crypto/md5,
+	crypto/rc4,
+	crypto/sha1,
+	crypto/sha256,
+	crypto/sha512
+	< CRYPTO;
+
+	CGO, fmt, net !< CRYPTO;
+
+	# CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
+	CRYPTO, FMT, math/big
+	< crypto/internal/boring/bbig
+	< crypto/rand
+	< crypto/ed25519
+	< encoding/asn1
+	< golang.org/x/crypto/cryptobyte/asn1
+	< golang.org/x/crypto/cryptobyte
+	< crypto/internal/bigmod
+	< crypto/dsa, crypto/elliptic, crypto/rsa
+	< crypto/ecdsa
+	< CRYPTO-MATH;
+
+	CGO, net !< CRYPTO-MATH;
+
+	# TLS, Prince of Dependencies.
+	CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
+	< golang.org/x/crypto/internal/alias
+	< golang.org/x/crypto/internal/subtle
+	< golang.org/x/crypto/chacha20
+	< golang.org/x/crypto/internal/poly1305
+	< golang.org/x/crypto/chacha20poly1305
+	< golang.org/x/crypto/hkdf
+	< crypto/x509/internal/macos
+	< crypto/x509/pkix;
+
+	crypto/internal/boring/fipstls, crypto/x509/pkix
+	< crypto/x509
+	< crypto/tls;
+
+	# crypto-aware packages
+
+	DEBUG, go/build, go/types, text/scanner, crypto/md5
+	< internal/pkgbits
+	< go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
+	< go/importer;
+
+	NET, crypto/rand, mime/quotedprintable
+	< mime/multipart;
+
+	crypto/tls
+	< net/smtp;
+
+	# HTTP, King of Dependencies.
+
+	FMT
+	< golang.org/x/net/http2/hpack
+	< net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
+
+	FMT, NET, container/list, encoding/binary, log
+	< golang.org/x/text/transform
+	< golang.org/x/text/unicode/norm
+	< golang.org/x/text/unicode/bidi
+	< golang.org/x/text/secure/bidirule
+	< golang.org/x/net/idna
+	< golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
+
+	NET, crypto/tls
+	< net/http/httptrace;
+
+	compress/gzip,
+	golang.org/x/net/http/httpguts,
+	golang.org/x/net/http/httpproxy,
+	golang.org/x/net/http2/hpack,
+	net/http/internal,
+	net/http/internal/ascii,
+	net/http/internal/testcert,
+	net/http/httptrace,
+	mime/multipart,
+	log
+	< net/http;
+
+	# HTTP-aware packages
+
+	encoding/json, net/http
+	< expvar;
+
+	net/http, net/http/internal/ascii
+	< net/http/cookiejar, net/http/httputil;
+
+	net/http, flag
+	< net/http/httptest;
+
+	net/http, regexp
+	< net/http/cgi
+	< net/http/fcgi;
+
+	# Profiling
+	FMT, compress/gzip, encoding/binary, text/tabwriter
+	< runtime/pprof;
+
+	OS, compress/gzip, regexp
+	< internal/profile;
+
+	html, internal/profile, net/http, runtime/pprof, runtime/trace
+	< net/http/pprof;
+
+	# RPC
+	encoding/gob, encoding/json, go/token, html/template, net/http
+	< net/rpc
+	< net/rpc/jsonrpc;
+
+	# System Information
+	internal/cpu, sync
+	< internal/sysinfo;
+
+	# Test-only
+	log
+	< testing/iotest
+	< testing/fstest;
+
+	FMT, flag, math/rand
+	< testing/quick;
+
+	FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
+	< testing;
+
+	FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
+	internal/godebug, math/rand, encoding/hex, crypto/sha256
+	< internal/fuzz;
+
+	internal/fuzz, internal/testlog, runtime/pprof, regexp
+	< testing/internal/testdeps;
+
+	OS, flag, testing, internal/cfg, internal/platform, internal/goroot
+	< internal/testenv;
+
+	OS, encoding/base64
+	< internal/obscuretestdata;
+
+	CGO, OS, fmt
+	< internal/testpty;
+
+	NET, testing, math/rand
+	< golang.org/x/net/nettest;
+
+	syscall
+	< os/exec/internal/fdtest;
+
+	FMT, container/heap, math/rand
+	< internal/trace;
+
+	FMT
+	< internal/diff, internal/txtar;
+
+	FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter, unsafe,
+	internal/coverage, internal/coverage/uleb128
+	< internal/coverage/cmerge,
+	  internal/coverage/pods,
+	  internal/coverage/slicereader,
+	  internal/coverage/slicewriter;
+
+	internal/coverage/slicereader, internal/coverage/slicewriter
+	< internal/coverage/stringtab
+	< internal/coverage/decodecounter, internal/coverage/decodemeta,
+	  internal/coverage/encodecounter, internal/coverage/encodemeta;
+
+	internal/coverage/cmerge
+	< internal/coverage/cformat;
+
+	runtime/debug,
+	internal/coverage/calloc,
+	internal/coverage/cformat,
+	internal/coverage/decodecounter, internal/coverage/decodemeta,
+	internal/coverage/encodecounter, internal/coverage/encodemeta,
+	internal/coverage/pods
+	< runtime/coverage;
+`
+
+// 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, d fs.DirEntry, err error) error {
+		if err != nil || !d.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" {
+			return filepath.SkipDir
+		}
+
+		pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
+		return nil
+	}
+	if err := filepath.WalkDir(src, walkFn); err != nil {
+		return nil, err
+	}
+	return pkgs, nil
+}
+
+func TestDependencies(t *testing.T) {
+	if !testenv.HasSrc() {
+		// 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 {
+		t.Fatal(err)
+	}
+	sort.Strings(all)
+
+	sawImport := map[string]map[string]bool{} // from package => to package => true
+	policy := depsPolicy(t)
+
+	for _, pkg := range all {
+		imports, err := findImports(pkg)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		if sawImport[pkg] == nil {
+			sawImport[pkg] = map[string]bool{}
+		}
+		var bad []string
+		for _, imp := range imports {
+			sawImport[pkg][imp] = true
+			if !policy.HasEdge(pkg, imp) {
+				bad = append(bad, imp)
+			}
+		}
+		if bad != nil {
+			t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
+		}
+	}
+}
+
+var buildIgnore = []byte("\n//go:build ignore")
+
+func findImports(pkg string) ([]string, error) {
+	vpkg := pkg
+	if strings.HasPrefix(pkg, "golang.org") {
+		vpkg = "vendor/" + pkg
+	}
+	dir := filepath.Join(Default.GOROOT, "src", vpkg)
+	files, err := os.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+	var imports []string
+	var haveImport = map[string]bool{}
+	if pkg == "crypto/internal/boring" {
+		haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
+	}
+	fset := token.NewFileSet()
+	for _, file := range files {
+		name := file.Name()
+		if name == "slice_go14.go" || name == "slice_go18.go" {
+			// These files are for compiler bootstrap with older versions of Go and not built in the standard build.
+			continue
+		}
+		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			continue
+		}
+		info := fileInfo{
+			name: filepath.Join(dir, name),
+			fset: fset,
+		}
+		f, err := os.Open(info.name)
+		if err != nil {
+			return nil, err
+		}
+		err = readGoInfo(f, &info)
+		f.Close()
+		if err != nil {
+			return nil, fmt.Errorf("reading %v: %v", name, err)
+		}
+		if info.parsed.Name.Name == "main" {
+			continue
+		}
+		if bytes.Contains(info.header, buildIgnore) {
+			continue
+		}
+		for _, imp := range info.imports {
+			path := imp.path
+			if !haveImport[path] {
+				haveImport[path] = true
+				imports = append(imports, path)
+			}
+		}
+	}
+	sort.Strings(imports)
+	return imports, nil
+}
+
+// depsPolicy returns a map m such that m[p][d] == true when p can import d.
+func depsPolicy(t *testing.T) *dag.Graph {
+	g, err := dag.Parse(depsRules)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return g
+}
+
+// TestStdlibLowercase tests that all standard library package names are
+// lowercase. See Issue 40065.
+func TestStdlibLowercase(t *testing.T) {
+	if !testenv.HasSrc() {
+		t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
+	}
+
+	ctxt := Default
+	all, err := listStdPkgs(ctxt.GOROOT)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, pkgname := range all {
+		if strings.ToLower(pkgname) != pkgname {
+			t.Errorf("package %q should not use upper-case path", pkgname)
+		}
+	}
+}
+
+// TestFindImports tests that findImports works.  See #43249.
+func TestFindImports(t *testing.T) {
+	imports, err := findImports("go/build")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("go/build imports %q", imports)
+	want := []string{"bytes", "os", "path/filepath", "strings"}
+wantLoop:
+	for _, w := range want {
+		for _, imp := range imports {
+			if imp == w {
+				continue wantLoop
+			}
+		}
+		t.Errorf("expected to find %q in import list", w)
+	}
+}