src/go/build/deps_test.go

   1 // Copyright 2022 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // This file exercises the import parser but also checks that
   6 // some low-level packages do not have new dependencies added.
   7
   8 package build
   9
  10 import (
  11         "bytes"
  12         "fmt"
  13         "go/token"
  14         "internal/dag"
  15         "internal/testenv"
  16         "io/fs"
  17         "os"
  18         "path/filepath"
  19         "runtime"
  20         "sort"
  21         "strings"
  22         "testing"
  23 )
  24
  25 // depsRules defines the expected dependencies between packages in
  26 // the Go source tree. It is a statement of policy.
  27 //
  28 // DO NOT CHANGE THIS DATA TO FIX BUILDS.
  29 // Existing packages should not have their constraints relaxed
  30 // without prior discussion.
  31 // Negative assertions should almost never be removed.
  32 //
  33 // "a < b" means package b can import package a.
  34 //
  35 // See `go doc internal/dag' for the full syntax.
  36 //
  37 // All-caps names are pseudo-names for specific points
  38 // in the dependency lattice.
  39 var depsRules = `
  40         # No dependencies allowed for any of these packages.
  41         NONE
  42         < constraints, container/list, container/ring,
  43           internal/cfg, internal/coverage, internal/coverage/rtcov,
  44           internal/coverage/uleb128, internal/coverage/calloc,
  45           internal/cpu, internal/goarch,
  46           internal/goexperiment, internal/goos,
  47           internal/goversion, internal/nettrace, internal/platform,
  48           unicode/utf8, unicode/utf16, unicode,
  49           unsafe;
  50
  51         # These packages depend only on internal/goarch and unsafe.
  52         internal/goarch, unsafe
  53         < internal/abi;
  54
  55         # RUNTIME is the core runtime group of packages, all of them very light-weight.
  56         internal/abi, internal/cpu, internal/goarch,
  57         internal/coverage/rtcov, internal/goexperiment, internal/goos, unsafe
  58         < internal/bytealg
  59         < internal/itoa
  60         < internal/unsafeheader
  61         < runtime/internal/sys
  62         < runtime/internal/syscall
  63         < runtime/internal/atomic
  64         < runtime/internal/math
  65         < runtime
  66         < sync/atomic
  67         < internal/race
  68         < sync
  69         < internal/reflectlite
  70         < errors
  71         < internal/oserror, math/bits
  72         < RUNTIME;
  73
  74         RUNTIME
  75         < sort
  76         < container/heap;
  77
  78         RUNTIME
  79         < io;
  80
  81         RUNTIME
  82         < arena;
  83
  84         syscall !< io;
  85         reflect !< sort;
  86
  87         RUNTIME, unicode/utf8
  88         < path;
  89
  90         unicode !< path;
  91
  92         # SYSCALL is RUNTIME plus the packages necessary for basic system calls.
  93         RUNTIME, unicode/utf8, unicode/utf16
  94         < internal/syscall/windows/sysdll, syscall/js
  95         < syscall
  96         < internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
  97         < internal/syscall/execenv
  98         < SYSCALL;
  99
 100         # TIME is SYSCALL plus the core packages about time, including context.
 101         SYSCALL
 102         < time/tzdata
 103         < time
 104         < context
 105         < TIME;
 106
 107         TIME, io, path, sort
 108         < io/fs;
 109
 110         # MATH is RUNTIME plus the basic math packages.
 111         RUNTIME
 112         < math
 113         < MATH;
 114
 115         unicode !< math;
 116
 117         MATH
 118         < math/cmplx;
 119
 120         MATH
 121         < math/rand;
 122
 123         MATH
 124         < runtime/metrics;
 125
 126         MATH, unicode/utf8
 127         < strconv;
 128
 129         unicode !< strconv;
 130
 131         # STR is basic string and buffer manipulation.
 132         RUNTIME, io, unicode/utf8, unicode/utf16, unicode
 133         < bytes, strings
 134         < bufio;
 135
 136         bufio, path, strconv
 137         < STR;
 138
 139         # OS is basic OS access, including helpers (path/filepath, os/exec, etc).
 140         # OS includes string routines, but those must be layered above package os.
 141         # OS does not include reflection.
 142         io/fs
 143         < internal/testlog
 144         < internal/poll
 145         < os
 146         < os/signal;
 147
 148         io/fs
 149         < embed;
 150
 151         unicode, fmt !< net, os, os/signal;
 152
 153         os/signal, STR
 154         < path/filepath
 155         < io/ioutil;
 156
 157         os < internal/godebug;
 158
 159         path/filepath, internal/godebug < os/exec;
 160
 161         io/ioutil, os/exec, os/signal
 162         < OS;
 163
 164         reflect !< OS;
 165
 166         OS
 167         < golang.org/x/sys/cpu;
 168
 169         # FMT is OS (which includes string routines) plus reflect and fmt.
 170         # It does not include package log, which should be avoided in core packages.
 171         arena, strconv, unicode
 172         < reflect;
 173
 174         os, reflect
 175         < internal/fmtsort
 176         < fmt;
 177
 178         OS, fmt
 179         < FMT;
 180
 181         log !< FMT;
 182
 183         # Misc packages needing only FMT.
 184         FMT
 185         < html,
 186           internal/dag,
 187           internal/goroot,
 188           internal/types/errors,
 189           mime/quotedprintable,
 190           net/internal/socktest,
 191           net/url,
 192           runtime/trace,
 193           text/scanner,
 194           text/tabwriter;
 195
 196         io, reflect
 197         < internal/saferio;
 198
 199         # encodings
 200         # core ones do not use fmt.
 201         io, strconv
 202         < encoding;
 203
 204         encoding, reflect
 205         < encoding/binary
 206         < encoding/base32, encoding/base64;
 207
 208         FMT, encoding < flag;
 209
 210         fmt !< encoding/base32, encoding/base64;
 211
 212         FMT, encoding/base32, encoding/base64, internal/saferio
 213         < encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
 214           encoding/json, encoding/pem, encoding/xml, mime;
 215
 216         # hashes
 217         io
 218         < hash
 219         < hash/adler32, hash/crc32, hash/crc64, hash/fnv, hash/maphash;
 220
 221         # math/big
 222         FMT, encoding/binary, math/rand
 223         < math/big;
 224
 225         # compression
 226         FMT, encoding/binary, hash/adler32, hash/crc32
 227         < compress/bzip2, compress/flate, compress/lzw
 228         < archive/zip, compress/gzip, compress/zlib;
 229
 230         # templates
 231         FMT
 232         < text/template/parse;
 233
 234         net/url, text/template/parse
 235         < text/template
 236         < internal/lazytemplate;
 237
 238         encoding/json, html, text/template
 239         < html/template;
 240
 241         # regexp
 242         FMT
 243         < regexp/syntax
 244         < regexp
 245         < internal/lazyregexp;
 246
 247         # suffix array
 248         encoding/binary, regexp
 249         < index/suffixarray;
 250
 251         # executable parsing
 252         FMT, encoding/binary, compress/zlib, internal/saferio
 253         < runtime/debug
 254         < debug/dwarf
 255         < debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
 256         < debug/buildinfo
 257         < DEBUG;
 258
 259         # go parser and friends.
 260         FMT
 261         < go/token
 262         < go/scanner
 263         < go/ast
 264         < go/internal/typeparams
 265         < go/parser;
 266
 267         FMT
 268         < go/build/constraint, go/doc/comment;
 269
 270         go/build/constraint, go/doc/comment, go/parser, text/tabwriter
 271         < go/printer
 272         < go/format;
 273
 274         go/doc/comment, go/parser, internal/lazyregexp, text/template
 275         < go/doc;
 276
 277         math/big, go/token
 278         < go/constant;
 279
 280         container/heap, go/constant, go/parser, internal/types/errors, regexp
 281         < go/types;
 282
 283         FMT, internal/goexperiment
 284         < internal/buildcfg;
 285
 286         go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion
 287         < go/build;
 288
 289         # databases
 290         FMT
 291         < database/sql/internal
 292         < database/sql/driver
 293         < database/sql;
 294
 295         # images
 296         FMT, compress/lzw, compress/zlib
 297         < image/color
 298         < image, image/color/palette
 299         < image/internal/imageutil
 300         < image/draw
 301         < image/gif, image/jpeg, image/png;
 302
 303         # cgo, delayed as long as possible.
 304         # If you add a dependency on CGO, you must add the package
 305         # to cgoPackages in cmd/dist/test.go as well.
 306         RUNTIME
 307         < C
 308         < runtime/cgo
 309         < CGO
 310         < runtime/msan, runtime/asan;
 311
 312         # runtime/race
 313         NONE < runtime/race/internal/amd64v1;
 314         NONE < runtime/race/internal/amd64v3;
 315         CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
 316
 317         # Bulk of the standard library must not use cgo.
 318         # The prohibition stops at net and os/user.
 319         C !< fmt, go/types, CRYPTO-MATH;
 320
 321         CGO, OS
 322         < plugin;
 323
 324         CGO, FMT
 325         < os/user
 326         < archive/tar;
 327
 328         sync
 329         < internal/singleflight;
 330
 331         os
 332         < golang.org/x/net/dns/dnsmessage,
 333           golang.org/x/net/lif,
 334           golang.org/x/net/route;
 335
 336         os, runtime, strconv, sync, unsafe,
 337         internal/godebug
 338         < internal/intern;
 339
 340         internal/bytealg, internal/intern, internal/itoa, math/bits, sort, strconv
 341         < net/netip;
 342
 343         # net is unavoidable when doing any networking,
 344         # so large dependencies must be kept out.
 345         # This is a long-looking list but most of these
 346         # are small with few dependencies.
 347         CGO,
 348         golang.org/x/net/dns/dnsmessage,
 349         golang.org/x/net/lif,
 350         golang.org/x/net/route,
 351         internal/godebug,
 352         internal/nettrace,
 353         internal/poll,
 354         internal/singleflight,
 355         internal/race,
 356         net/netip,
 357         os
 358         < net;
 359
 360         fmt, unicode !< net;
 361         math/rand !< net; # net uses runtime instead
 362
 363         # NET is net plus net-helper packages.
 364         FMT, net
 365         < net/textproto;
 366
 367         mime, net/textproto, net/url
 368         < NET;
 369
 370         # logging - most packages should not import; http and up is allowed
 371         FMT
 372         < log;
 373
 374         log !< crypto/tls, database/sql, go/importer, testing;
 375
 376         FMT, log, net
 377         < log/syslog;
 378
 379         NET, log
 380         < net/mail;
 381
 382         NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
 383         sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
 384         crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
 385
 386         # CRYPTO is core crypto algorithms - no cgo, fmt, net.
 387         # Unfortunately, stuck with reflect via encoding/binary.
 388         crypto/internal/boring/sig,
 389         crypto/internal/boring/syso,
 390         encoding/binary,
 391         golang.org/x/sys/cpu,
 392         hash, embed
 393         < crypto
 394         < crypto/subtle
 395         < crypto/internal/alias
 396         < crypto/internal/randutil
 397         < crypto/internal/nistec/fiat
 398         < crypto/internal/nistec
 399         < crypto/internal/edwards25519/field
 400         < crypto/internal/edwards25519, crypto/ecdh
 401         < crypto/cipher;
 402
 403         crypto/cipher,
 404         crypto/internal/boring/bcache
 405         < crypto/internal/boring
 406         < crypto/boring
 407         < crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
 408           crypto/sha1, crypto/sha256, crypto/sha512
 409         < CRYPTO;
 410
 411         CGO, fmt, net !< CRYPTO;
 412
 413         # CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
 414         CRYPTO, FMT, math/big
 415         < crypto/internal/boring/bbig
 416         < crypto/rand
 417         < crypto/ed25519
 418         < encoding/asn1
 419         < golang.org/x/crypto/cryptobyte/asn1
 420         < golang.org/x/crypto/cryptobyte
 421         < crypto/dsa, crypto/elliptic, crypto/rsa
 422         < crypto/ecdsa
 423         < CRYPTO-MATH;
 424
 425         CGO, net !< CRYPTO-MATH;
 426
 427         # TLS, Prince of Dependencies.
 428         CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
 429         < golang.org/x/crypto/internal/alias
 430         < golang.org/x/crypto/internal/subtle
 431         < golang.org/x/crypto/chacha20
 432         < golang.org/x/crypto/internal/poly1305
 433         < golang.org/x/crypto/chacha20poly1305
 434         < golang.org/x/crypto/hkdf
 435         < crypto/x509/internal/macos
 436         < crypto/x509/pkix;
 437
 438         crypto/internal/boring/fipstls, crypto/x509/pkix
 439         < crypto/x509
 440         < crypto/tls;
 441
 442         # crypto-aware packages
 443
 444         DEBUG, go/build, go/types, text/scanner, crypto/md5
 445         < internal/pkgbits
 446         < go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
 447         < go/importer;
 448
 449         NET, crypto/rand, mime/quotedprintable
 450         < mime/multipart;
 451
 452         crypto/tls
 453         < net/smtp;
 454
 455         # HTTP, King of Dependencies.
 456
 457         FMT
 458         < golang.org/x/net/http2/hpack
 459         < net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
 460
 461         FMT, NET, container/list, encoding/binary, log
 462         < golang.org/x/text/transform
 463         < golang.org/x/text/unicode/norm
 464         < golang.org/x/text/unicode/bidi
 465         < golang.org/x/text/secure/bidirule
 466         < golang.org/x/net/idna
 467         < golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
 468
 469         NET, crypto/tls
 470         < net/http/httptrace;
 471
 472         compress/gzip,
 473         golang.org/x/net/http/httpguts,
 474         golang.org/x/net/http/httpproxy,
 475         golang.org/x/net/http2/hpack,
 476         net/http/internal,
 477         net/http/internal/ascii,
 478         net/http/internal/testcert,
 479         net/http/httptrace,
 480         mime/multipart,
 481         log
 482         < net/http;
 483
 484         # HTTP-aware packages
 485
 486         encoding/json, net/http
 487         < expvar;
 488
 489         net/http, net/http/internal/ascii
 490         < net/http/cookiejar, net/http/httputil;
 491
 492         net/http, flag
 493         < net/http/httptest;
 494
 495         net/http, regexp
 496         < net/http/cgi
 497         < net/http/fcgi;
 498
 499         # Profiling
 500         FMT, compress/gzip, encoding/binary, text/tabwriter
 501         < runtime/pprof;
 502
 503         OS, compress/gzip, regexp
 504         < internal/profile;
 505
 506         html, internal/profile, net/http, runtime/pprof, runtime/trace
 507         < net/http/pprof;
 508
 509         # RPC
 510         encoding/gob, encoding/json, go/token, html/template, net/http
 511         < net/rpc
 512         < net/rpc/jsonrpc;
 513
 514         # System Information
 515         internal/cpu, sync
 516         < internal/sysinfo;
 517
 518         # Test-only
 519         log
 520         < testing/iotest
 521         < testing/fstest;
 522
 523         FMT, flag, math/rand
 524         < testing/quick;
 525
 526         FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
 527         < testing;
 528
 529         FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
 530         internal/godebug, math/rand, encoding/hex, crypto/sha256
 531         < internal/fuzz;
 532
 533         internal/fuzz, internal/testlog, runtime/pprof, regexp
 534         < testing/internal/testdeps;
 535
 536         OS, flag, testing, internal/cfg, internal/platform
 537         < internal/testenv;
 538
 539         OS, encoding/base64
 540         < internal/obscuretestdata;
 541
 542         CGO, OS, fmt
 543         < os/signal/internal/pty;
 544
 545         NET, testing, math/rand
 546         < golang.org/x/net/nettest;
 547
 548         syscall
 549         < os/exec/internal/fdtest;
 550
 551         FMT, container/heap, math/rand
 552         < internal/trace;
 553
 554         FMT
 555         < internal/diff, internal/txtar;
 556
 557         FMT, os
 558         < internal/coverage/slicewriter;
 559
 560         encoding/binary, internal/unsafeheader, unsafe
 561         < internal/coverage/slicereader;
 562
 563         FMT, math, internal/coverage
 564         < internal/coverage/cmerge;
 565
 566         FMT, math, internal/coverage, internal/coverage/cmerge, text/tabwriter
 567         < internal/coverage/cformat;
 568
 569         FMT, io, internal/coverage/slicereader, internal/coverage/uleb128
 570         < internal/coverage/stringtab;
 571
 572         FMT, encoding/binary, internal/coverage, internal/coverage/stringtab,
 573         io, os, bufio, crypto/md5
 574         < internal/coverage/encodemeta;
 575
 576         FMT, bufio, encoding/binary, internal/coverage,
 577         internal/coverage/stringtab, internal/coverage/slicewriter, os, unsafe
 578         < internal/coverage/encodecounter;
 579
 580         FMT, encoding/binary, internal/coverage, io, os,
 581         internal/coverage/slicereader, internal/coverage/stringtab
 582         < internal/coverage/decodecounter;
 583
 584         FMT, encoding/binary, internal/coverage, io, os,
 585         crypto/md5, internal/coverage/stringtab
 586         < internal/coverage/decodemeta;
 587
 588         FMT, internal/coverage, os,
 589         path/filepath, regexp, sort, strconv
 590         < internal/coverage/pods;
 591
 592         FMT, bufio, crypto/md5, encoding/binary, runtime/debug,
 593         internal/coverage, internal/coverage/cmerge,
 594         internal/coverage/cformat, internal/coverage/calloc,
 595         internal/coverage/decodecounter, internal/coverage/decodemeta,
 596         internal/coverage/encodecounter, internal/coverage/encodemeta,
 597         internal/coverage/pods, os, path/filepath, reflect, time, unsafe
 598         < runtime/coverage;
 599 `
 600
 601 // listStdPkgs returns the same list of packages as "go list std".
 602 func listStdPkgs(goroot string) ([]string, error) {
 603         // Based on cmd/go's matchPackages function.
 604         var pkgs []string
 605
 606         src := filepath.Join(goroot, "src") + string(filepath.Separator)
 607         walkFn := func(path string, d fs.DirEntry, err error) error {
 608                 if err != nil || !d.IsDir() || path == src {
 609                         return nil
 610                 }
 611
 612                 base := filepath.Base(path)
 613                 if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
 614                         return filepath.SkipDir
 615                 }
 616
 617                 name := filepath.ToSlash(path[len(src):])
 618                 if name == "builtin" || name == "cmd" {
 619                         return filepath.SkipDir
 620                 }
 621
 622                 pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
 623                 return nil
 624         }
 625         if err := filepath.WalkDir(src, walkFn); err != nil {
 626                 return nil, err
 627         }
 628         return pkgs, nil
 629 }
 630
 631 func TestDependencies(t *testing.T) {
 632         if !testenv.HasSrc() {
 633                 // Tests run in a limited file system and we do not
 634                 // provide access to every source file.
 635                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 636         }
 637
 638         ctxt := Default
 639         all, err := listStdPkgs(ctxt.GOROOT)
 640         if err != nil {
 641                 t.Fatal(err)
 642         }
 643         sort.Strings(all)
 644
 645         sawImport := map[string]map[string]bool{} // from package => to package => true
 646         policy := depsPolicy(t)
 647
 648         for _, pkg := range all {
 649                 imports, err := findImports(pkg)
 650                 if err != nil {
 651                         t.Error(err)
 652                         continue
 653                 }
 654                 if sawImport[pkg] == nil {
 655                         sawImport[pkg] = map[string]bool{}
 656                 }
 657                 var bad []string
 658                 for _, imp := range imports {
 659                         sawImport[pkg][imp] = true
 660                         if !policy.HasEdge(pkg, imp) {
 661                                 bad = append(bad, imp)
 662                         }
 663                 }
 664                 if bad != nil {
 665                         t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
 666                 }
 667         }
 668 }
 669
 670 var buildIgnore = []byte("\n//go:build ignore")
 671
 672 func findImports(pkg string) ([]string, error) {
 673         vpkg := pkg
 674         if strings.HasPrefix(pkg, "golang.org") {
 675                 vpkg = "vendor/" + pkg
 676         }
 677         dir := filepath.Join(Default.GOROOT, "src", vpkg)
 678         files, err := os.ReadDir(dir)
 679         if err != nil {
 680                 return nil, err
 681         }
 682         var imports []string
 683         var haveImport = map[string]bool{}
 684         if pkg == "crypto/internal/boring" {
 685                 haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
 686         }
 687         fset := token.NewFileSet()
 688         for _, file := range files {
 689                 name := file.Name()
 690                 if name == "slice_go14.go" || name == "slice_go18.go" {
 691                         // These files are for compiler bootstrap with older versions of Go and not built in the standard build.
 692                         continue
 693                 }
 694                 if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
 695                         continue
 696                 }
 697                 info := fileInfo{
 698                         name: filepath.Join(dir, name),
 699                         fset: fset,
 700                 }
 701                 f, err := os.Open(info.name)
 702                 if err != nil {
 703                         return nil, err
 704                 }
 705                 err = readGoInfo(f, &info)
 706                 f.Close()
 707                 if err != nil {
 708                         return nil, fmt.Errorf("reading %v: %v", name, err)
 709                 }
 710                 if info.parsed.Name.Name == "main" {
 711                         continue
 712                 }
 713                 if bytes.Contains(info.header, buildIgnore) {
 714                         continue
 715                 }
 716                 for _, imp := range info.imports {
 717                         path := imp.path
 718                         if !haveImport[path] {
 719                                 haveImport[path] = true
 720                                 imports = append(imports, path)
 721                         }
 722                 }
 723         }
 724         sort.Strings(imports)
 725         return imports, nil
 726 }
 727
 728 // depsPolicy returns a map m such that m[p][d] == true when p can import d.
 729 func depsPolicy(t *testing.T) *dag.Graph {
 730         g, err := dag.Parse(depsRules)
 731         if err != nil {
 732                 t.Fatal(err)
 733         }
 734         return g
 735 }
 736
 737 // TestStdlibLowercase tests that all standard library package names are
 738 // lowercase. See Issue 40065.
 739 func TestStdlibLowercase(t *testing.T) {
 740         if !testenv.HasSrc() {
 741                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 742         }
 743
 744         ctxt := Default
 745         all, err := listStdPkgs(ctxt.GOROOT)
 746         if err != nil {
 747                 t.Fatal(err)
 748         }
 749
 750         for _, pkgname := range all {
 751                 if strings.ToLower(pkgname) != pkgname {
 752                         t.Errorf("package %q should not use upper-case path", pkgname)
 753                 }
 754         }
 755 }
 756
 757 // TestFindImports tests that findImports works.  See #43249.
 758 func TestFindImports(t *testing.T) {
 759         imports, err := findImports("go/build")
 760         if err != nil {
 761                 t.Fatal(err)
 762         }
 763         t.Logf("go/build imports %q", imports)
 764         want := []string{"bytes", "os", "path/filepath", "strings"}
 765 wantLoop:
 766         for _, w := range want {
 767                 for _, imp := range imports {
 768                         if imp == w {
 769                                 continue wantLoop
 770                         }
 771                 }
 772                 t.Errorf("expected to find %q in import list", w)
 773         }
 774 }