Source file 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  	"slices"
    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  	< unsafe
    43  	< cmp,
    44  	  container/list,
    45  	  container/ring,
    46  	  internal/byteorder,
    47  	  internal/cfg,
    48  	  internal/coverage,
    49  	  internal/coverage/rtcov,
    50  	  internal/coverage/uleb128,
    51  	  internal/coverage/calloc,
    52  	  internal/cpu,
    53  	  internal/goarch,
    54  	  internal/godebugs,
    55  	  internal/goexperiment,
    56  	  internal/goos,
    57  	  internal/goversion,
    58  	  internal/nettrace,
    59  	  internal/platform,
    60  	  internal/profilerecord,
    61  	  internal/trace/traceviewer/format,
    62  	  log/internal,
    63  	  math/bits,
    64  	  unicode,
    65  	  unicode/utf8,
    66  	  unicode/utf16;
    67  
    68  	internal/goarch < internal/abi;
    69  	internal/byteorder, internal/goarch < internal/chacha8rand;
    70  
    71  	# RUNTIME is the core runtime group of packages, all of them very light-weight.
    72  	internal/abi,
    73  	internal/chacha8rand,
    74  	internal/coverage/rtcov,
    75  	internal/cpu,
    76  	internal/goarch,
    77  	internal/godebugs,
    78  	internal/goexperiment,
    79  	internal/goos,
    80  	internal/profilerecord,
    81  	math/bits
    82  	< internal/bytealg
    83  	< internal/stringslite
    84  	< internal/itoa
    85  	< internal/unsafeheader
    86  	< runtime/internal/sys
    87  	< internal/runtime/syscall
    88  	< internal/runtime/atomic
    89  	< internal/runtime/exithook
    90  	< runtime/internal/math
    91  	< runtime
    92  	< sync/atomic
    93  	< internal/race
    94  	< internal/msan
    95  	< internal/asan
    96  	< internal/weak
    97  	< sync
    98  	< internal/bisect
    99  	< internal/godebug
   100  	< internal/reflectlite
   101  	< errors
   102  	< internal/oserror;
   103  
   104  	cmp, internal/race, math/bits
   105  	< iter
   106  	< maps, slices;
   107  
   108  	internal/oserror, maps, slices
   109  	< RUNTIME;
   110  
   111  	RUNTIME
   112  	< sort
   113  	< container/heap;
   114  
   115  	RUNTIME
   116  	< io;
   117  
   118  	RUNTIME
   119  	< arena;
   120  
   121  	syscall !< io;
   122  	reflect !< sort;
   123  
   124  	RUNTIME, unicode/utf8
   125  	< path;
   126  
   127  	unicode !< path;
   128  
   129  	# SYSCALL is RUNTIME plus the packages necessary for basic system calls.
   130  	RUNTIME, unicode/utf8, unicode/utf16
   131  	< internal/syscall/windows/sysdll, syscall/js
   132  	< syscall
   133  	< internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
   134  	< internal/syscall/execenv
   135  	< SYSCALL;
   136  
   137  	# TIME is SYSCALL plus the core packages about time, including context.
   138  	SYSCALL
   139  	< time/tzdata
   140  	< time
   141  	< context
   142  	< TIME;
   143  
   144  	TIME, io, path, slices
   145  	< io/fs;
   146  
   147  	# MATH is RUNTIME plus the basic math packages.
   148  	RUNTIME
   149  	< math
   150  	< MATH;
   151  
   152  	unicode !< math;
   153  
   154  	MATH
   155  	< math/cmplx;
   156  
   157  	MATH
   158  	< math/rand, math/rand/v2;
   159  
   160  	MATH
   161  	< runtime/metrics;
   162  
   163  	RUNTIME, math/rand/v2
   164  	< internal/concurrent;
   165  
   166  	MATH, unicode/utf8
   167  	< strconv;
   168  
   169  	unicode !< strconv;
   170  
   171  	# STR is basic string and buffer manipulation.
   172  	RUNTIME, io, unicode/utf8, unicode/utf16, unicode
   173  	< bytes, strings
   174  	< bufio;
   175  
   176  	bufio, path, strconv
   177  	< STR;
   178  
   179  	RUNTIME, internal/concurrent
   180  	< unique;
   181  
   182  	# OS is basic OS access, including helpers (path/filepath, os/exec, etc).
   183  	# OS includes string routines, but those must be layered above package os.
   184  	# OS does not include reflection.
   185  	io/fs
   186  	< internal/testlog
   187  	< internal/poll
   188  	< internal/filepathlite
   189  	< os
   190  	< os/signal;
   191  
   192  	io/fs
   193  	< embed;
   194  
   195  	unicode, fmt !< net, os, os/signal;
   196  
   197  	os/signal, internal/filepathlite, STR
   198  	< path/filepath
   199  	< io/ioutil;
   200  
   201  	path/filepath, internal/godebug < os/exec;
   202  
   203  	io/ioutil, os/exec, os/signal
   204  	< OS;
   205  
   206  	reflect !< OS;
   207  
   208  	OS
   209  	< golang.org/x/sys/cpu;
   210  
   211  	# FMT is OS (which includes string routines) plus reflect and fmt.
   212  	# It does not include package log, which should be avoided in core packages.
   213  	arena, strconv, unicode
   214  	< reflect;
   215  
   216  	os, reflect
   217  	< internal/fmtsort
   218  	< fmt;
   219  
   220  	OS, fmt
   221  	< FMT;
   222  
   223  	log !< FMT;
   224  
   225  	# Misc packages needing only FMT.
   226  	FMT
   227  	< html,
   228  	  internal/dag,
   229  	  internal/goroot,
   230  	  internal/types/errors,
   231  	  mime/quotedprintable,
   232  	  net/internal/socktest,
   233  	  net/url,
   234  	  runtime/trace,
   235  	  text/scanner,
   236  	  text/tabwriter;
   237  
   238  	io, reflect
   239  	< internal/saferio;
   240  
   241  	# encodings
   242  	# core ones do not use fmt.
   243  	io, strconv, slices
   244  	< encoding;
   245  
   246  	encoding, reflect
   247  	< encoding/binary
   248  	< encoding/base32, encoding/base64;
   249  
   250  	FMT, encoding < flag;
   251  
   252  	fmt !< encoding/base32, encoding/base64;
   253  
   254  	FMT, encoding/base32, encoding/base64, internal/saferio
   255  	< encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
   256  	  encoding/json, encoding/pem, encoding/xml, mime;
   257  
   258  	# hashes
   259  	io
   260  	< hash
   261  	< hash/adler32, hash/crc32, hash/crc64, hash/fnv;
   262  
   263  	# math/big
   264  	FMT, math/rand
   265  	< math/big;
   266  
   267  	# compression
   268  	FMT, encoding/binary, hash/adler32, hash/crc32, sort
   269  	< compress/bzip2, compress/flate, compress/lzw, internal/zstd
   270  	< archive/zip, compress/gzip, compress/zlib;
   271  
   272  	# templates
   273  	FMT
   274  	< text/template/parse;
   275  
   276  	net/url, text/template/parse
   277  	< text/template
   278  	< internal/lazytemplate;
   279  
   280  	# regexp
   281  	FMT, sort
   282  	< regexp/syntax
   283  	< regexp
   284  	< internal/lazyregexp;
   285  
   286  	encoding/json, html, text/template, regexp
   287  	< html/template;
   288  
   289  	# suffix array
   290  	encoding/binary, regexp
   291  	< index/suffixarray;
   292  
   293  	# executable parsing
   294  	FMT, encoding/binary, compress/zlib, internal/saferio, internal/zstd, sort
   295  	< runtime/debug
   296  	< debug/dwarf
   297  	< debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
   298  	< debug/buildinfo
   299  	< DEBUG;
   300  
   301  	# go parser and friends.
   302  	FMT, sort
   303  	< internal/gover
   304  	< go/version
   305  	< go/token
   306  	< go/scanner
   307  	< go/ast
   308  	< go/internal/typeparams;
   309  
   310  	FMT
   311  	< go/build/constraint;
   312  
   313  	FMT, sort
   314  	< go/doc/comment;
   315  
   316  	go/internal/typeparams, go/build/constraint
   317  	< go/parser;
   318  
   319  	go/doc/comment, go/parser, text/tabwriter
   320  	< go/printer
   321  	< go/format;
   322  
   323  	math/big, go/token
   324  	< go/constant;
   325  
   326  	FMT, internal/goexperiment
   327  	< internal/buildcfg;
   328  
   329  	container/heap, go/constant, go/parser, internal/buildcfg, internal/goversion, internal/types/errors
   330  	< go/types;
   331  
   332  	# The vast majority of standard library packages should not be resorting to regexp.
   333  	# go/types is a good chokepoint. It shouldn't use regexp, nor should anything
   334  	# that is low-enough level to be used by go/types.
   335  	regexp !< go/types;
   336  
   337  	go/doc/comment, go/parser, internal/lazyregexp, text/template
   338  	< go/doc;
   339  
   340  	go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion, internal/platform
   341  	< go/build;
   342  
   343  	# databases
   344  	FMT
   345  	< database/sql/internal
   346  	< database/sql/driver;
   347  
   348  	database/sql/driver, math/rand/v2 < database/sql;
   349  
   350  	# images
   351  	FMT, compress/lzw, compress/zlib
   352  	< image/color
   353  	< image, image/color/palette
   354  	< image/internal/imageutil
   355  	< image/draw
   356  	< image/gif, image/jpeg, image/png;
   357  
   358  	# cgo, delayed as long as possible.
   359  	# If you add a dependency on CGO, you must add the package
   360  	# to cgoPackages in cmd/dist/test.go as well.
   361  	RUNTIME
   362  	< C
   363  	< runtime/cgo
   364  	< CGO
   365  	< runtime/msan, runtime/asan;
   366  
   367  	# runtime/race
   368  	NONE < runtime/race/internal/amd64v1;
   369  	NONE < runtime/race/internal/amd64v3;
   370  	CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
   371  
   372  	# Bulk of the standard library must not use cgo.
   373  	# The prohibition stops at net and os/user.
   374  	C !< fmt, go/types, CRYPTO-MATH, log/slog;
   375  
   376  	CGO, OS
   377  	< plugin;
   378  
   379  	CGO, FMT
   380  	< os/user
   381  	< archive/tar;
   382  
   383  	sync
   384  	< internal/singleflight;
   385  
   386  	os
   387  	< golang.org/x/net/dns/dnsmessage,
   388  	  golang.org/x/net/lif,
   389  	  golang.org/x/net/route;
   390  
   391  	internal/bytealg, internal/itoa, math/bits, slices, strconv, unique
   392  	< net/netip;
   393  
   394  	# net is unavoidable when doing any networking,
   395  	# so large dependencies must be kept out.
   396  	# This is a long-looking list but most of these
   397  	# are small with few dependencies.
   398  	CGO,
   399  	golang.org/x/net/dns/dnsmessage,
   400  	golang.org/x/net/lif,
   401  	golang.org/x/net/route,
   402  	internal/godebug,
   403  	internal/nettrace,
   404  	internal/poll,
   405  	internal/singleflight,
   406  	net/netip,
   407  	os,
   408  	sort
   409  	< net;
   410  
   411  	fmt, unicode !< net;
   412  	math/rand !< net; # net uses runtime instead
   413  
   414  	# NET is net plus net-helper packages.
   415  	FMT, net
   416  	< net/textproto;
   417  
   418  	mime, net/textproto, net/url
   419  	< NET;
   420  
   421  	# logging - most packages should not import; http and up is allowed
   422  	FMT, log/internal
   423  	< log;
   424  
   425  	log, log/slog !< crypto/tls, database/sql, go/importer, testing;
   426  
   427  	FMT, log, net
   428  	< log/syslog;
   429  
   430  	RUNTIME
   431  	< log/slog/internal, log/slog/internal/buffer;
   432  
   433  	FMT,
   434  	encoding, encoding/json,
   435  	log, log/internal,
   436  	log/slog/internal, log/slog/internal/buffer,
   437  	slices
   438  	< log/slog
   439  	< log/slog/internal/slogtest, log/slog/internal/benchmarks;
   440  
   441  	NET, log
   442  	< net/mail;
   443  
   444  	NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
   445  	sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
   446  	crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
   447  
   448  	# CRYPTO is core crypto algorithms - no cgo, fmt, net.
   449  	crypto/internal/boring/sig,
   450  	crypto/internal/boring/syso,
   451  	golang.org/x/sys/cpu,
   452  	hash, embed
   453  	< crypto
   454  	< crypto/subtle
   455  	< crypto/internal/alias
   456  	< crypto/cipher;
   457  
   458  	crypto/cipher,
   459  	crypto/internal/boring/bcache
   460  	< crypto/internal/boring
   461  	< crypto/boring;
   462  
   463  	crypto/internal/alias
   464  	< crypto/internal/randutil
   465  	< crypto/internal/nistec/fiat
   466  	< crypto/internal/nistec
   467  	< crypto/internal/edwards25519/field
   468  	< crypto/internal/edwards25519;
   469  
   470  	crypto/boring
   471  	< crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
   472  	  crypto/sha1, crypto/sha256, crypto/sha512;
   473  
   474  	crypto/boring, crypto/internal/edwards25519/field
   475  	< crypto/ecdh;
   476  
   477  	# Unfortunately, stuck with reflect via encoding/binary.
   478  	encoding/binary, crypto/boring < golang.org/x/crypto/sha3;
   479  
   480  	crypto/aes,
   481  	crypto/des,
   482  	crypto/ecdh,
   483  	crypto/hmac,
   484  	crypto/internal/edwards25519,
   485  	crypto/md5,
   486  	crypto/rc4,
   487  	crypto/sha1,
   488  	crypto/sha256,
   489  	crypto/sha512,
   490  	golang.org/x/crypto/sha3
   491  	< CRYPTO;
   492  
   493  	CGO, fmt, net !< CRYPTO;
   494  
   495  	# CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
   496  	CRYPTO, FMT, math/big
   497  	< crypto/internal/boring/bbig
   498  	< crypto/rand
   499  	< crypto/internal/mlkem768
   500  	< crypto/ed25519
   501  	< encoding/asn1
   502  	< golang.org/x/crypto/cryptobyte/asn1
   503  	< golang.org/x/crypto/cryptobyte
   504  	< crypto/internal/bigmod
   505  	< crypto/dsa, crypto/elliptic, crypto/rsa
   506  	< crypto/ecdsa
   507  	< CRYPTO-MATH;
   508  
   509  	CGO, net !< CRYPTO-MATH;
   510  
   511  	# TLS, Prince of Dependencies.
   512  	CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
   513  	< golang.org/x/crypto/internal/alias
   514  	< golang.org/x/crypto/internal/subtle
   515  	< golang.org/x/crypto/chacha20
   516  	< golang.org/x/crypto/internal/poly1305
   517  	< golang.org/x/crypto/chacha20poly1305
   518  	< golang.org/x/crypto/hkdf
   519  	< crypto/internal/hpke
   520  	< crypto/x509/internal/macos
   521  	< crypto/x509/pkix;
   522  
   523  	crypto/internal/boring/fipstls, crypto/x509/pkix
   524  	< crypto/x509
   525  	< crypto/tls;
   526  
   527  	# crypto-aware packages
   528  
   529  	DEBUG, go/build, go/types, text/scanner, crypto/md5
   530  	< internal/pkgbits
   531  	< go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
   532  	< go/importer;
   533  
   534  	NET, crypto/rand, mime/quotedprintable
   535  	< mime/multipart;
   536  
   537  	crypto/tls
   538  	< net/smtp;
   539  
   540  	crypto/rand
   541  	< hash/maphash; # for purego implementation
   542  
   543  	# HTTP, King of Dependencies.
   544  
   545  	FMT
   546  	< golang.org/x/net/http2/hpack
   547  	< net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
   548  
   549  	FMT, NET, container/list, encoding/binary, log
   550  	< golang.org/x/text/transform
   551  	< golang.org/x/text/unicode/norm
   552  	< golang.org/x/text/unicode/bidi
   553  	< golang.org/x/text/secure/bidirule
   554  	< golang.org/x/net/idna
   555  	< golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
   556  
   557  	NET, crypto/tls
   558  	< net/http/httptrace;
   559  
   560  	compress/gzip,
   561  	golang.org/x/net/http/httpguts,
   562  	golang.org/x/net/http/httpproxy,
   563  	golang.org/x/net/http2/hpack,
   564  	net/http/internal,
   565  	net/http/internal/ascii,
   566  	net/http/internal/testcert,
   567  	net/http/httptrace,
   568  	mime/multipart,
   569  	log
   570  	< net/http;
   571  
   572  	# HTTP-aware packages
   573  
   574  	encoding/json, net/http
   575  	< expvar;
   576  
   577  	net/http, net/http/internal/ascii
   578  	< net/http/cookiejar, net/http/httputil;
   579  
   580  	net/http, flag
   581  	< net/http/httptest;
   582  
   583  	net/http, regexp
   584  	< net/http/cgi
   585  	< net/http/fcgi;
   586  
   587  	# Profiling
   588  	FMT, compress/gzip, encoding/binary, sort, text/tabwriter
   589  	< runtime/pprof;
   590  
   591  	OS, compress/gzip, internal/lazyregexp
   592  	< internal/profile;
   593  
   594  	html, internal/profile, net/http, runtime/pprof, runtime/trace
   595  	< net/http/pprof;
   596  
   597  	# RPC
   598  	encoding/gob, encoding/json, go/token, html/template, net/http
   599  	< net/rpc
   600  	< net/rpc/jsonrpc;
   601  
   602  	# System Information
   603  	bufio, bytes, internal/cpu, io, os, strings, sync
   604  	< internal/sysinfo;
   605  
   606  	# Test-only
   607  	log
   608  	< testing/iotest
   609  	< testing/fstest;
   610  
   611  	FMT, flag, math/rand
   612  	< testing/quick;
   613  
   614  	FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
   615  	< testing;
   616  
   617  	log/slog, testing
   618  	< testing/slogtest;
   619  
   620  	FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
   621  	internal/godebug, math/rand, encoding/hex, crypto/sha256
   622  	< internal/fuzz;
   623  
   624  	OS, flag, testing, internal/cfg, internal/platform, internal/goroot
   625  	< internal/testenv;
   626  
   627  	OS, encoding/base64
   628  	< internal/obscuretestdata;
   629  
   630  	CGO, OS, fmt
   631  	< internal/testpty;
   632  
   633  	NET, testing, math/rand
   634  	< golang.org/x/net/nettest;
   635  
   636  	syscall
   637  	< os/exec/internal/fdtest;
   638  
   639  	FMT, sort
   640  	< internal/diff;
   641  
   642  	FMT
   643  	< internal/txtar;
   644  
   645  	CRYPTO-MATH, testing
   646  	< crypto/internal/cryptotest;
   647  
   648  	# v2 execution trace parser.
   649  	FMT
   650  	< internal/trace/event;
   651  
   652  	internal/trace/event
   653  	< internal/trace/event/go122;
   654  
   655  	FMT, io, internal/trace/event/go122
   656  	< internal/trace/version;
   657  
   658  	FMT, encoding/binary, internal/trace/version
   659  	< internal/trace/raw;
   660  
   661  	FMT, internal/trace/event, internal/trace/version, io, sort, encoding/binary
   662  	< internal/trace/internal/oldtrace;
   663  
   664  	FMT, encoding/binary, internal/trace/version, internal/trace/internal/oldtrace, container/heap, math/rand
   665  	< internal/trace;
   666  
   667  	regexp, internal/trace, internal/trace/raw, internal/txtar
   668  	< internal/trace/testtrace;
   669  
   670  	regexp, internal/txtar, internal/trace, internal/trace/raw
   671  	< internal/trace/internal/testgen/go122;
   672  
   673  	# cmd/trace dependencies.
   674  	FMT,
   675  	embed,
   676  	encoding/json,
   677  	html/template,
   678  	internal/profile,
   679  	internal/trace,
   680  	internal/trace/traceviewer/format,
   681  	net/http
   682  	< internal/trace/traceviewer;
   683  
   684  	# Coverage.
   685  	FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter,
   686  	internal/coverage, internal/coverage/uleb128
   687  	< internal/coverage/cmerge,
   688  	  internal/coverage/pods,
   689  	  internal/coverage/slicereader,
   690  	  internal/coverage/slicewriter;
   691  
   692  	internal/coverage/slicereader, internal/coverage/slicewriter
   693  	< internal/coverage/stringtab
   694  	< internal/coverage/decodecounter, internal/coverage/decodemeta,
   695  	  internal/coverage/encodecounter, internal/coverage/encodemeta;
   696  
   697  	internal/coverage/cmerge
   698  	< internal/coverage/cformat;
   699  
   700  	internal/coverage, crypto/sha256, FMT
   701  	< cmd/internal/cov/covcmd;
   702  
   703  	encoding/json,
   704  	runtime/debug,
   705  	internal/coverage/calloc,
   706  	internal/coverage/cformat,
   707  	internal/coverage/decodecounter, internal/coverage/decodemeta,
   708  	internal/coverage/encodecounter, internal/coverage/encodemeta,
   709  	internal/coverage/pods
   710  	< internal/coverage/cfile
   711  	< runtime/coverage;
   712  
   713  	internal/coverage/cfile, internal/fuzz, internal/testlog, runtime/pprof, regexp
   714  	< testing/internal/testdeps;
   715  
   716  	# Test-only packages can have anything they want
   717  	CGO, internal/syscall/unix < net/internal/cgotest;
   718  
   719  
   720  `
   721  
   722  // listStdPkgs returns the same list of packages as "go list std".
   723  func listStdPkgs(goroot string) ([]string, error) {
   724  	// Based on cmd/go's matchPackages function.
   725  	var pkgs []string
   726  
   727  	src := filepath.Join(goroot, "src") + string(filepath.Separator)
   728  	walkFn := func(path string, d fs.DirEntry, err error) error {
   729  		if err != nil || !d.IsDir() || path == src {
   730  			return nil
   731  		}
   732  
   733  		base := filepath.Base(path)
   734  		if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
   735  			return filepath.SkipDir
   736  		}
   737  
   738  		name := filepath.ToSlash(path[len(src):])
   739  		if name == "builtin" || name == "cmd" {
   740  			return filepath.SkipDir
   741  		}
   742  
   743  		pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
   744  		return nil
   745  	}
   746  	if err := filepath.WalkDir(src, walkFn); err != nil {
   747  		return nil, err
   748  	}
   749  	return pkgs, nil
   750  }
   751  
   752  func TestDependencies(t *testing.T) {
   753  	if !testenv.HasSrc() {
   754  		// Tests run in a limited file system and we do not
   755  		// provide access to every source file.
   756  		t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
   757  	}
   758  
   759  	ctxt := Default
   760  	all, err := listStdPkgs(ctxt.GOROOT)
   761  	if err != nil {
   762  		t.Fatal(err)
   763  	}
   764  	slices.Sort(all)
   765  
   766  	sawImport := map[string]map[string]bool{} // from package => to package => true
   767  	policy := depsPolicy(t)
   768  
   769  	for _, pkg := range all {
   770  		imports, err := findImports(pkg)
   771  		if err != nil {
   772  			t.Error(err)
   773  			continue
   774  		}
   775  		if sawImport[pkg] == nil {
   776  			sawImport[pkg] = map[string]bool{}
   777  		}
   778  		var bad []string
   779  		for _, imp := range imports {
   780  			sawImport[pkg][imp] = true
   781  			if !policy.HasEdge(pkg, imp) {
   782  				bad = append(bad, imp)
   783  			}
   784  		}
   785  		if bad != nil {
   786  			t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
   787  		}
   788  	}
   789  }
   790  
   791  var buildIgnore = []byte("\n//go:build ignore")
   792  
   793  func findImports(pkg string) ([]string, error) {
   794  	vpkg := pkg
   795  	if strings.HasPrefix(pkg, "golang.org") {
   796  		vpkg = "vendor/" + pkg
   797  	}
   798  	dir := filepath.Join(Default.GOROOT, "src", vpkg)
   799  	files, err := os.ReadDir(dir)
   800  	if err != nil {
   801  		return nil, err
   802  	}
   803  	var imports []string
   804  	var haveImport = map[string]bool{}
   805  	if pkg == "crypto/internal/boring" {
   806  		haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
   807  	}
   808  	fset := token.NewFileSet()
   809  	for _, file := range files {
   810  		name := file.Name()
   811  		if name == "slice_go14.go" || name == "slice_go18.go" {
   812  			// These files are for compiler bootstrap with older versions of Go and not built in the standard build.
   813  			continue
   814  		}
   815  		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
   816  			continue
   817  		}
   818  		info := fileInfo{
   819  			name: filepath.Join(dir, name),
   820  			fset: fset,
   821  		}
   822  		f, err := os.Open(info.name)
   823  		if err != nil {
   824  			return nil, err
   825  		}
   826  		err = readGoInfo(f, &info)
   827  		f.Close()
   828  		if err != nil {
   829  			return nil, fmt.Errorf("reading %v: %v", name, err)
   830  		}
   831  		if info.parsed.Name.Name == "main" {
   832  			continue
   833  		}
   834  		if bytes.Contains(info.header, buildIgnore) {
   835  			continue
   836  		}
   837  		for _, imp := range info.imports {
   838  			path := imp.path
   839  			if !haveImport[path] {
   840  				haveImport[path] = true
   841  				imports = append(imports, path)
   842  			}
   843  		}
   844  	}
   845  	slices.Sort(imports)
   846  	return imports, nil
   847  }
   848  
   849  // depsPolicy returns a map m such that m[p][d] == true when p can import d.
   850  func depsPolicy(t *testing.T) *dag.Graph {
   851  	g, err := dag.Parse(depsRules)
   852  	if err != nil {
   853  		t.Fatal(err)
   854  	}
   855  	return g
   856  }
   857  
   858  // TestStdlibLowercase tests that all standard library package names are
   859  // lowercase. See Issue 40065.
   860  func TestStdlibLowercase(t *testing.T) {
   861  	if !testenv.HasSrc() {
   862  		t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
   863  	}
   864  
   865  	ctxt := Default
   866  	all, err := listStdPkgs(ctxt.GOROOT)
   867  	if err != nil {
   868  		t.Fatal(err)
   869  	}
   870  
   871  	for _, pkgname := range all {
   872  		if strings.ToLower(pkgname) != pkgname {
   873  			t.Errorf("package %q should not use upper-case path", pkgname)
   874  		}
   875  	}
   876  }
   877  
   878  // TestFindImports tests that findImports works.  See #43249.
   879  func TestFindImports(t *testing.T) {
   880  	imports, err := findImports("go/build")
   881  	if err != nil {
   882  		t.Fatal(err)
   883  	}
   884  	t.Logf("go/build imports %q", imports)
   885  	want := []string{"bytes", "os", "path/filepath", "strings"}
   886  wantLoop:
   887  	for _, w := range want {
   888  		for _, imp := range imports {
   889  			if imp == w {
   890  				continue wantLoop
   891  			}
   892  		}
   893  		t.Errorf("expected to find %q in import list", w)
   894  	}
   895  }
   896  

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