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  	"slices"
    20  	"strings"
    21  	"testing"
    22  )
    23  
    24  // depsRules defines the expected dependencies between packages in
    25  // the Go source tree. It is a statement of policy.
    26  //
    27  // DO NOT CHANGE THIS DATA TO FIX BUILDS.
    28  // Existing packages should not have their constraints relaxed
    29  // without prior discussion.
    30  // Negative assertions should almost never be removed.
    31  //
    32  // "a < b" means package b can import package a.
    33  //
    34  // See `go doc internal/dag` for the full syntax.
    35  //
    36  // All-caps names are pseudo-names for specific points
    37  // in the dependency lattice.
    38  var depsRules = `
    39  	# No dependencies allowed for any of these packages.
    40  	NONE
    41  	< unsafe
    42  	< cmp,
    43  	  container/list,
    44  	  container/ring,
    45  	  internal/byteorder,
    46  	  internal/cfg,
    47  	  internal/coverage,
    48  	  internal/coverage/rtcov,
    49  	  internal/coverage/uleb128,
    50  	  internal/coverage/calloc,
    51  	  internal/cpu,
    52  	  internal/goarch,
    53  	  internal/godebugs,
    54  	  internal/goexperiment,
    55  	  internal/goos,
    56  	  internal/goversion,
    57  	  internal/nettrace,
    58  	  internal/platform,
    59  	  internal/profilerecord,
    60  	  internal/syslist,
    61  	  internal/trace/tracev2,
    62  	  internal/trace/traceviewer/format,
    63  	  log/internal,
    64  	  math/bits,
    65  	  structs,
    66  	  unicode,
    67  	  unicode/utf8,
    68  	  unicode/utf16;
    69  
    70  	internal/goarch < internal/abi;
    71  	internal/byteorder, internal/cpu, internal/goarch < internal/chacha8rand;
    72  
    73  	# RUNTIME is the core runtime group of packages, all of them very light-weight.
    74  	internal/abi,
    75  	internal/chacha8rand,
    76  	internal/coverage/rtcov,
    77  	internal/cpu,
    78  	internal/goarch,
    79  	internal/godebugs,
    80  	internal/goexperiment,
    81  	internal/goos,
    82  	internal/profilerecord,
    83  	internal/trace/tracev2,
    84  	math/bits,
    85  	structs
    86  	< internal/bytealg
    87  	< internal/stringslite
    88  	< internal/itoa
    89  	< internal/unsafeheader
    90  	< internal/race
    91  	< internal/msan
    92  	< internal/asan
    93  	< internal/runtime/sys
    94  	< internal/runtime/syscall/linux
    95  	< internal/runtime/syscall/windows
    96  	< internal/runtime/atomic
    97  	< internal/runtime/exithook
    98  	< internal/runtime/gc
    99  	< internal/runtime/math
   100  	< internal/runtime/maps
   101  	< internal/runtime/strconv
   102  	< internal/runtime/cgroup
   103  	< runtime
   104  	< sync/atomic
   105  	< internal/sync
   106  	< weak
   107  	< internal/synctest
   108  	< sync
   109  	< internal/bisect
   110  	< internal/godebug
   111  	< internal/reflectlite
   112  	< errors
   113  	< internal/oserror;
   114  
   115  	cmp, runtime, math/bits
   116  	< iter
   117  	< maps, slices;
   118  
   119  	internal/oserror, maps, slices
   120  	< RUNTIME;
   121  
   122  	RUNTIME
   123  	< sort
   124  	< container/heap
   125  	< unique;
   126  
   127  	RUNTIME
   128  	< io;
   129  
   130  	RUNTIME
   131  	< arena;
   132  
   133  	syscall !< io;
   134  	reflect !< sort;
   135  
   136  	RUNTIME, unicode/utf8
   137  	< path;
   138  
   139  	unicode !< path;
   140  
   141  	# SYSCALL is RUNTIME plus the packages necessary for basic system calls.
   142  	RUNTIME, unicode/utf8, unicode/utf16, internal/synctest
   143  	< internal/syscall/windows/sysdll, syscall/js
   144  	< syscall
   145  	< internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
   146  	< internal/syscall/execenv
   147  	< SYSCALL;
   148  
   149  	# TIME is SYSCALL plus the core packages about time, including context.
   150  	SYSCALL
   151  	< time/tzdata
   152  	< time
   153  	< context
   154  	< TIME;
   155  
   156  	TIME, io, path, slices
   157  	< io/fs;
   158  
   159  	# MATH is RUNTIME plus the basic math packages.
   160  	RUNTIME
   161  	< math
   162  	< MATH;
   163  
   164  	unicode !< math;
   165  
   166  	MATH
   167  	< math/cmplx;
   168  
   169  	MATH
   170  	< math/rand, math/rand/v2;
   171  
   172  	MATH
   173  	< runtime/metrics;
   174  
   175  	MATH, unicode/utf8
   176  	< strconv;
   177  
   178  	unicode !< strconv;
   179  
   180  	# STR is basic string and buffer manipulation.
   181  	RUNTIME, io, unicode/utf8, unicode/utf16, unicode
   182  	< bytes, strings
   183  	< bufio;
   184  
   185  	bufio, path, strconv
   186  	< STR;
   187  
   188  	# OS is basic OS access, including helpers (path/filepath, os/exec, etc).
   189  	# OS includes string routines, but those must be layered above package os.
   190  	# OS does not include reflection.
   191  	io/fs
   192  	< internal/testlog
   193  	< internal/poll
   194  	< internal/filepathlite
   195  	< os
   196  	< os/signal;
   197  
   198  	io/fs
   199  	< embed;
   200  
   201  	unicode, fmt !< net, os, os/signal;
   202  
   203  	os/signal, internal/filepathlite, STR
   204  	< path/filepath
   205  	< io/ioutil;
   206  
   207  	path/filepath, internal/godebug < os/exec;
   208  
   209  	io/ioutil, os/exec, os/signal
   210  	< OS;
   211  
   212  	reflect !< OS;
   213  
   214  	OS
   215  	< golang.org/x/sys/cpu;
   216  
   217  	# FMT is OS (which includes string routines) plus reflect and fmt.
   218  	# It does not include package log, which should be avoided in core packages.
   219  	arena, strconv, unicode
   220  	< reflect;
   221  
   222  	os, reflect
   223  	< internal/fmtsort
   224  	< fmt;
   225  
   226  	OS, fmt
   227  	< FMT;
   228  
   229  	log !< FMT;
   230  
   231  	# Misc packages needing only FMT.
   232  	FMT
   233  	< html,
   234  	  internal/dag,
   235  	  internal/goroot,
   236  	  internal/types/errors,
   237  	  mime/quotedprintable,
   238  	  net/internal/socktest,
   239  	  net/url,
   240  	  runtime/trace,
   241  	  text/scanner,
   242  	  text/tabwriter;
   243  
   244  	io, reflect
   245  	< internal/saferio;
   246  
   247  	# encodings
   248  	# core ones do not use fmt.
   249  	io, strconv, slices
   250  	< encoding, encoding/base32, encoding/base64;
   251  
   252  	encoding, reflect
   253  	< encoding/binary;
   254  
   255  	FMT, encoding < flag;
   256  
   257  	fmt !< encoding/base32, encoding/base64;
   258  
   259  	FMT, encoding, encoding/base32, encoding/base64, encoding/binary,
   260  	internal/saferio
   261  	< encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
   262  	  encoding/pem, encoding/xml, mime;
   263  
   264  	STR, errors
   265  	< encoding/json/internal
   266  	< encoding/json/internal/jsonflags
   267  	< encoding/json/internal/jsonopts
   268  	< encoding/json/internal/jsonwire
   269  	< encoding/json/jsontext;
   270  
   271  	FMT,
   272  	encoding/hex,
   273  	encoding/base32,
   274  	encoding/base64,
   275  	encoding/binary,
   276  	encoding/json/jsontext,
   277  	encoding/json/internal,
   278  	encoding/json/internal/jsonflags,
   279  	encoding/json/internal/jsonopts,
   280  	encoding/json/internal/jsonwire
   281  	< encoding/json/v2
   282  	< encoding/json;
   283  
   284  	# hashes
   285  	io
   286  	< hash
   287  	< hash/adler32, hash/crc32, hash/crc64, hash/fnv;
   288  
   289  	# math/big
   290  	FMT, math/rand
   291  	< math/big;
   292  
   293  	# compression
   294  	FMT, encoding/binary, hash/adler32, hash/crc32, sort
   295  	< compress/bzip2, compress/flate, compress/lzw, internal/zstd
   296  	< archive/zip, compress/gzip, compress/zlib;
   297  
   298  	# templates
   299  	FMT
   300  	< text/template/parse;
   301  
   302  	net/url, text/template/parse
   303  	< text/template
   304  	< internal/lazytemplate;
   305  
   306  	# regexp
   307  	FMT, sort
   308  	< regexp/syntax
   309  	< regexp
   310  	< internal/lazyregexp;
   311  
   312  	encoding/json, html, text/template, regexp
   313  	< html/template;
   314  
   315  	# suffix array
   316  	encoding/binary, regexp
   317  	< index/suffixarray;
   318  
   319  	# executable parsing
   320  	FMT, encoding/binary, compress/zlib, internal/saferio, internal/zstd, sort
   321  	< runtime/debug
   322  	< debug/dwarf
   323  	< debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
   324  	< debug/buildinfo
   325  	< DEBUG;
   326  
   327  	# go parser and friends.
   328  	FMT, sort
   329  	< internal/gover
   330  	< go/version
   331  	< go/token
   332  	< go/scanner
   333  	< go/ast
   334  	< go/internal/typeparams;
   335  
   336  	FMT
   337  	< go/build/constraint;
   338  
   339  	FMT, sort
   340  	< go/doc/comment;
   341  
   342  	go/internal/typeparams, go/build/constraint
   343  	< go/parser;
   344  
   345  	go/doc/comment, go/parser, text/tabwriter
   346  	< go/printer
   347  	< go/format;
   348  
   349  	math/big, go/token
   350  	< go/constant;
   351  
   352  	FMT, internal/goexperiment
   353  	< internal/buildcfg;
   354  
   355  	container/heap, go/constant, go/parser, internal/buildcfg, internal/goversion, internal/types/errors
   356  	< go/types;
   357  
   358  	# The vast majority of standard library packages should not be resorting to regexp.
   359  	# go/types is a good chokepoint. It shouldn't use regexp, nor should anything
   360  	# that is low-enough level to be used by go/types.
   361  	regexp !< go/types;
   362  
   363  	go/doc/comment, go/parser, internal/lazyregexp, text/template
   364  	< go/doc;
   365  
   366  	go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion, internal/platform, internal/syslist
   367  	< go/build;
   368  
   369  	# databases
   370  	FMT
   371  	< database/sql/internal
   372  	< database/sql/driver;
   373  
   374  	database/sql/driver, math/rand/v2 < database/sql;
   375  
   376  	# images
   377  	FMT, compress/lzw, compress/zlib
   378  	< image/color
   379  	< image, image/color/palette
   380  	< image/internal/imageutil
   381  	< image/draw
   382  	< image/gif, image/jpeg, image/png;
   383  
   384  	# cgo, delayed as long as possible.
   385  	# If you add a dependency on CGO, you must add the package
   386  	# to cgoPackages in cmd/dist/test.go as well.
   387  	RUNTIME
   388  	< C
   389  	< runtime/cgo
   390  	< CGO
   391  	< runtime/msan, runtime/asan;
   392  
   393  	# runtime/race
   394  	NONE < runtime/race/internal/amd64v1;
   395  	NONE < runtime/race/internal/amd64v3;
   396  	CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
   397  
   398  	# Bulk of the standard library must not use cgo.
   399  	# The prohibition stops at net and os/user.
   400  	C !< fmt, go/types, CRYPTO-MATH, log/slog;
   401  
   402  	CGO, OS
   403  	< plugin;
   404  
   405  	CGO, FMT
   406  	< os/user
   407  	< archive/tar;
   408  
   409  	sync
   410  	< internal/singleflight;
   411  
   412  	os
   413  	< golang.org/x/net/dns/dnsmessage,
   414  	  golang.org/x/net/lif;
   415  
   416  	internal/bytealg, internal/itoa, math/bits, slices, strconv, unique
   417  	< net/netip;
   418  
   419  	os, net/netip
   420  	< internal/routebsd;
   421  
   422  	# net is unavoidable when doing any networking,
   423  	# so large dependencies must be kept out.
   424  	# This is a long-looking list but most of these
   425  	# are small with few dependencies.
   426  	CGO,
   427  	golang.org/x/net/dns/dnsmessage,
   428  	golang.org/x/net/lif,
   429  	internal/godebug,
   430  	internal/nettrace,
   431  	internal/poll,
   432  	internal/routebsd,
   433  	internal/singleflight,
   434  	net/netip,
   435  	os,
   436  	sort
   437  	< net;
   438  
   439  	fmt, unicode !< net;
   440  	math/rand !< net; # net uses runtime instead
   441  
   442  	# NET is net plus net-helper packages.
   443  	FMT, net
   444  	< net/textproto;
   445  
   446  	mime, net/textproto, net/url
   447  	< NET;
   448  
   449  	# logging - most packages should not import; http and up is allowed
   450  	FMT, log/internal
   451  	< log;
   452  
   453  	log, log/slog !< crypto/tls, database/sql, go/importer, testing;
   454  
   455  	FMT, log, net
   456  	< log/syslog;
   457  
   458  	RUNTIME
   459  	< log/slog/internal, log/slog/internal/buffer;
   460  
   461  	FMT,
   462  	encoding, encoding/json,
   463  	log, log/internal,
   464  	log/slog/internal, log/slog/internal/buffer,
   465  	slices
   466  	< log/slog
   467  	< log/slog/internal/slogtest, log/slog/internal/benchmarks;
   468  
   469  	NET, log
   470  	< net/mail;
   471  
   472  	# FIPS is the FIPS 140 module.
   473  	# It must not depend on external crypto packages.
   474  	# Package hash is ok as it's only the interface.
   475  	# See also fips140deps.AllowedInternalPackages.
   476  
   477  	io, math/rand/v2 < crypto/internal/randutil;
   478  
   479  	STR < crypto/internal/impl;
   480  
   481  	OS < crypto/internal/sysrand
   482  	< crypto/internal/entropy;
   483  
   484  	internal/byteorder < crypto/internal/fips140deps/byteorder;
   485  	internal/cpu, internal/goarch < crypto/internal/fips140deps/cpu;
   486  	internal/godebug < crypto/internal/fips140deps/godebug;
   487  
   488  	STR, hash,
   489  	crypto/internal/impl,
   490  	crypto/internal/entropy,
   491  	crypto/internal/randutil,
   492  	crypto/internal/fips140deps/byteorder,
   493  	crypto/internal/fips140deps/cpu,
   494  	crypto/internal/fips140deps/godebug
   495  	< crypto/internal/fips140
   496  	< crypto/internal/fips140/alias
   497  	< crypto/internal/fips140/subtle
   498  	< crypto/internal/fips140/sha256
   499  	< crypto/internal/fips140/sha512
   500  	< crypto/internal/fips140/sha3
   501  	< crypto/internal/fips140/hmac
   502  	< crypto/internal/fips140/check
   503  	< crypto/internal/fips140/pbkdf2
   504  	< crypto/internal/fips140/aes
   505  	< crypto/internal/fips140/drbg
   506  	< crypto/internal/fips140/aes/gcm
   507  	< crypto/internal/fips140/hkdf
   508  	< crypto/internal/fips140/mlkem
   509  	< crypto/internal/fips140/ssh
   510  	< crypto/internal/fips140/tls12
   511  	< crypto/internal/fips140/tls13
   512  	< crypto/internal/fips140/bigmod
   513  	< crypto/internal/fips140/nistec/fiat
   514  	< crypto/internal/fips140/nistec
   515  	< crypto/internal/fips140/ecdh
   516  	< crypto/internal/fips140/ecdsa
   517  	< crypto/internal/fips140/edwards25519/field
   518  	< crypto/internal/fips140/edwards25519
   519  	< crypto/internal/fips140/ed25519
   520  	< crypto/internal/fips140/rsa
   521  	< FIPS < crypto/fips140;
   522  
   523  	crypto !< FIPS;
   524  
   525  	# CRYPTO is core crypto algorithms - no cgo, fmt, net.
   526  	# Mostly wrappers around the FIPS module.
   527  
   528  	NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
   529  	sync/atomic < crypto/internal/boring/bcache;
   530  
   531  	FIPS, internal/godebug, embed,
   532  	crypto/internal/boring/sig,
   533  	crypto/internal/boring/syso,
   534  	crypto/internal/boring/bcache
   535  	< crypto/internal/fips140only
   536  	< crypto
   537  	< crypto/subtle
   538  	< crypto/sha3
   539  	< crypto/internal/fips140hash
   540  	< crypto/cipher
   541  	< crypto/internal/boring
   542  	< crypto/boring
   543  	< crypto/aes,
   544  	  crypto/des,
   545  	  crypto/rc4,
   546  	  crypto/md5,
   547  	  crypto/sha1,
   548  	  crypto/sha256,
   549  	  crypto/sha512,
   550  	  crypto/hmac,
   551  	  crypto/hkdf,
   552  	  crypto/pbkdf2,
   553  	  crypto/ecdh,
   554  	  crypto/mlkem
   555  	< CRYPTO;
   556  
   557  	CGO, fmt, net !< CRYPTO;
   558  
   559  	# CRYPTO-MATH is crypto that exposes math/big APIs - no cgo, net; fmt now ok.
   560  
   561  	CRYPTO, FMT, math/big
   562  	< crypto/internal/boring/bbig
   563  	< crypto/internal/fips140cache
   564  	< crypto/rand
   565  	< crypto/ed25519 # depends on crypto/rand.Reader
   566  	< encoding/asn1
   567  	< golang.org/x/crypto/cryptobyte/asn1
   568  	< golang.org/x/crypto/cryptobyte
   569  	< crypto/dsa, crypto/elliptic, crypto/rsa
   570  	< crypto/ecdsa
   571  	< CRYPTO-MATH;
   572  
   573  	CGO, net !< CRYPTO-MATH;
   574  
   575  	# TLS, Prince of Dependencies.
   576  
   577  	crypto/fips140, sync/atomic < crypto/tls/internal/fips140tls;
   578  
   579  	crypto/internal/boring/sig, crypto/tls/internal/fips140tls < crypto/tls/fipsonly;
   580  
   581  	CRYPTO, golang.org/x/sys/cpu, encoding/binary, reflect
   582  	< golang.org/x/crypto/internal/alias
   583  	< golang.org/x/crypto/internal/subtle
   584  	< golang.org/x/crypto/chacha20
   585  	< golang.org/x/crypto/internal/poly1305
   586  	< golang.org/x/crypto/chacha20poly1305;
   587  
   588  	CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem,
   589  	golang.org/x/crypto/chacha20poly1305, crypto/tls/internal/fips140tls
   590  	< crypto/internal/hpke
   591  	< crypto/x509/internal/macos
   592  	< crypto/x509/pkix
   593  	< crypto/x509
   594  	< crypto/tls;
   595  
   596  	# crypto-aware packages
   597  
   598  	DEBUG, go/build, go/types, text/scanner, crypto/sha256
   599  	< internal/pkgbits, internal/exportdata
   600  	< go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
   601  	< go/importer;
   602  
   603  	NET, crypto/rand, mime/quotedprintable
   604  	< mime/multipart;
   605  
   606  	crypto/tls
   607  	< net/smtp;
   608  
   609  	crypto/rand
   610  	< hash/maphash; # for purego implementation
   611  
   612  	# HTTP, King of Dependencies.
   613  
   614  	FMT
   615  	< golang.org/x/net/http2/hpack
   616  	< net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
   617  
   618  	FMT, NET, container/list, encoding/binary, log
   619  	< golang.org/x/text/transform
   620  	< golang.org/x/text/unicode/norm
   621  	< golang.org/x/text/unicode/bidi
   622  	< golang.org/x/text/secure/bidirule
   623  	< golang.org/x/net/idna
   624  	< golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
   625  
   626  	NET, crypto/tls
   627  	< net/http/httptrace;
   628  
   629  	compress/gzip,
   630  	golang.org/x/net/http/httpguts,
   631  	golang.org/x/net/http/httpproxy,
   632  	golang.org/x/net/http2/hpack,
   633  	net/http/internal,
   634  	net/http/internal/ascii,
   635  	net/http/internal/testcert,
   636  	net/http/httptrace,
   637  	mime/multipart,
   638  	log
   639  	< net/http/internal/httpcommon
   640  	< net/http;
   641  
   642  	# HTTP-aware packages
   643  
   644  	encoding/json, net/http
   645  	< expvar;
   646  
   647  	net/http, net/http/internal/ascii
   648  	< net/http/cookiejar, net/http/httputil;
   649  
   650  	net/http, flag
   651  	< net/http/httptest;
   652  
   653  	net/http, regexp
   654  	< net/http/cgi
   655  	< net/http/fcgi;
   656  
   657  	# Profiling
   658  	FMT, compress/gzip, encoding/binary, sort, text/tabwriter
   659  	< runtime/pprof;
   660  
   661  	OS, compress/gzip, internal/lazyregexp
   662  	< internal/profile;
   663  
   664  	html, internal/profile, net/http, runtime/pprof, runtime/trace
   665  	< net/http/pprof;
   666  
   667  	# RPC
   668  	encoding/gob, encoding/json, go/token, html/template, net/http
   669  	< net/rpc
   670  	< net/rpc/jsonrpc;
   671  
   672  	# System Information
   673  	bufio, bytes, internal/cpu, io, os, strings, sync
   674  	< internal/sysinfo;
   675  
   676  	# Test-only
   677  	log
   678  	< testing/iotest
   679  	< testing/fstest;
   680  
   681  	FMT, flag, math/rand
   682  	< testing/quick;
   683  
   684  	FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
   685  	< testing;
   686  
   687  	log/slog, testing
   688  	< testing/slogtest;
   689  
   690  	FMT, crypto/sha256, encoding/binary, encoding/json,
   691  	go/ast, go/parser, go/token,
   692  	internal/godebug, math/rand, encoding/hex
   693  	< internal/fuzz;
   694  
   695  	OS, flag, testing, internal/cfg, internal/platform, internal/goroot
   696  	< internal/testenv;
   697  
   698  	OS, encoding/base64
   699  	< internal/obscuretestdata;
   700  
   701  	CGO, OS, fmt
   702  	< internal/testpty;
   703  
   704  	NET, testing, math/rand
   705  	< golang.org/x/net/nettest;
   706  
   707  	syscall
   708  	< os/exec/internal/fdtest;
   709  
   710  	FMT, sort
   711  	< internal/diff;
   712  
   713  	FMT
   714  	< internal/txtar;
   715  
   716  	internal/synctest, testing
   717  	< testing/synctest;
   718  
   719  	testing
   720  	< internal/testhash;
   721  
   722  	CRYPTO-MATH, testing, internal/testenv, internal/testhash, encoding/json
   723  	< crypto/internal/cryptotest;
   724  
   725  	CGO, FMT
   726  	< crypto/internal/sysrand/internal/seccomp;
   727  
   728  	FIPS
   729  	< crypto/internal/fips140/check/checktest;
   730  
   731  	# v2 execution trace parser.
   732  	FMT, io, internal/trace/tracev2
   733  	< internal/trace/version;
   734  
   735  	FMT, encoding/binary, internal/trace/version
   736  	< internal/trace/raw;
   737  
   738  	FMT, internal/trace/version, io, sort, encoding/binary
   739  	< internal/trace/internal/tracev1;
   740  
   741  	FMT, encoding/binary, internal/trace/version, internal/trace/internal/tracev1, container/heap, math/rand
   742  	< internal/trace;
   743  
   744  	regexp, internal/trace, internal/trace/raw, internal/txtar
   745  	< internal/trace/testtrace;
   746  
   747  	regexp, internal/txtar, internal/trace, internal/trace/raw
   748  	< internal/trace/internal/testgen;
   749  
   750  	# cmd/trace dependencies.
   751  	FMT,
   752  	embed,
   753  	encoding/json,
   754  	html/template,
   755  	internal/profile,
   756  	internal/trace,
   757  	internal/trace/traceviewer/format,
   758  	net/http
   759  	< internal/trace/traceviewer;
   760  
   761  	# Coverage.
   762  	FMT, hash/fnv, encoding/binary, regexp, sort, text/tabwriter,
   763  	internal/coverage, internal/coverage/uleb128
   764  	< internal/coverage/cmerge,
   765  	  internal/coverage/pods,
   766  	  internal/coverage/slicereader,
   767  	  internal/coverage/slicewriter;
   768  
   769  	internal/coverage/slicereader, internal/coverage/slicewriter
   770  	< internal/coverage/stringtab
   771  	< internal/coverage/decodecounter, internal/coverage/decodemeta,
   772  	  internal/coverage/encodecounter, internal/coverage/encodemeta;
   773  
   774  	internal/coverage/cmerge
   775  	< internal/coverage/cformat;
   776  
   777  	internal/coverage, crypto/sha256, FMT
   778  	< cmd/internal/cov/covcmd;
   779  
   780  	encoding/json,
   781  	runtime/debug,
   782  	internal/coverage/calloc,
   783  	internal/coverage/cformat,
   784  	internal/coverage/decodecounter, internal/coverage/decodemeta,
   785  	internal/coverage/encodecounter, internal/coverage/encodemeta,
   786  	internal/coverage/pods
   787  	< internal/coverage/cfile
   788  	< runtime/coverage;
   789  
   790  	internal/coverage/cfile, internal/fuzz, internal/testlog, runtime/pprof, regexp
   791  	< testing/internal/testdeps;
   792  
   793  	# Test-only packages can have anything they want
   794  	FMT, compress/gzip, embed, encoding/binary < encoding/json/internal/jsontest;
   795  	CGO, internal/syscall/unix < net/internal/cgotest;
   796  	FMT < math/big/internal/asmgen;
   797  
   798  	FMT, testing < internal/cgrouptest;
   799  	C, CGO < internal/runtime/cgobench;
   800  `
   801  
   802  // listStdPkgs returns the same list of packages as "go list std".
   803  func listStdPkgs(goroot string) ([]string, error) {
   804  	// Based on cmd/go's matchPackages function.
   805  	var pkgs []string
   806  
   807  	src := filepath.Join(goroot, "src") + string(filepath.Separator)
   808  	walkFn := func(path string, d fs.DirEntry, err error) error {
   809  		if err != nil || !d.IsDir() || path == src {
   810  			return nil
   811  		}
   812  
   813  		base := filepath.Base(path)
   814  		if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
   815  			return filepath.SkipDir
   816  		}
   817  
   818  		name := filepath.ToSlash(path[len(src):])
   819  		if name == "builtin" || name == "cmd" {
   820  			return filepath.SkipDir
   821  		}
   822  
   823  		pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
   824  		return nil
   825  	}
   826  	if err := filepath.WalkDir(src, walkFn); err != nil {
   827  		return nil, err
   828  	}
   829  	return pkgs, nil
   830  }
   831  
   832  func TestDependencies(t *testing.T) {
   833  	testenv.MustHaveSource(t)
   834  
   835  	ctxt := Default
   836  	all, err := listStdPkgs(ctxt.GOROOT)
   837  	if err != nil {
   838  		t.Fatal(err)
   839  	}
   840  	slices.Sort(all)
   841  
   842  	sawImport := map[string]map[string]bool{} // from package => to package => true
   843  	policy := depsPolicy(t)
   844  
   845  	for _, pkg := range all {
   846  		imports, err := findImports(pkg)
   847  		if err != nil {
   848  			t.Error(err)
   849  			continue
   850  		}
   851  		if sawImport[pkg] == nil {
   852  			sawImport[pkg] = map[string]bool{}
   853  		}
   854  		var bad []string
   855  		for _, imp := range imports {
   856  			sawImport[pkg][imp] = true
   857  			if !policy.HasEdge(pkg, imp) {
   858  				bad = append(bad, imp)
   859  			}
   860  		}
   861  		if bad != nil {
   862  			t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
   863  		}
   864  	}
   865  }
   866  
   867  var buildIgnore = []byte("\n//go:build ignore")
   868  
   869  func findImports(pkg string) ([]string, error) {
   870  	vpkg := pkg
   871  	if strings.HasPrefix(pkg, "golang.org") {
   872  		vpkg = "vendor/" + pkg
   873  	}
   874  	dir := filepath.Join(Default.GOROOT, "src", vpkg)
   875  	files, err := os.ReadDir(dir)
   876  	if err != nil {
   877  		return nil, err
   878  	}
   879  	var imports []string
   880  	var haveImport = map[string]bool{}
   881  	if pkg == "crypto/internal/boring" {
   882  		haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
   883  	}
   884  	fset := token.NewFileSet()
   885  	for _, file := range files {
   886  		name := file.Name()
   887  		if name == "slice_go14.go" || name == "slice_go18.go" {
   888  			// These files are for compiler bootstrap with older versions of Go and not built in the standard build.
   889  			continue
   890  		}
   891  		if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
   892  			continue
   893  		}
   894  		info := fileInfo{
   895  			name: filepath.Join(dir, name),
   896  			fset: fset,
   897  		}
   898  		f, err := os.Open(info.name)
   899  		if err != nil {
   900  			return nil, err
   901  		}
   902  		err = readGoInfo(f, &info)
   903  		f.Close()
   904  		if err != nil {
   905  			return nil, fmt.Errorf("reading %v: %v", name, err)
   906  		}
   907  		if info.parsed.Name.Name == "main" {
   908  			continue
   909  		}
   910  		if bytes.Contains(info.header, buildIgnore) {
   911  			continue
   912  		}
   913  		for _, imp := range info.imports {
   914  			path := imp.path
   915  			if !haveImport[path] {
   916  				haveImport[path] = true
   917  				imports = append(imports, path)
   918  			}
   919  		}
   920  	}
   921  	slices.Sort(imports)
   922  	return imports, nil
   923  }
   924  
   925  // depsPolicy returns a map m such that m[p][d] == true when p can import d.
   926  func depsPolicy(t *testing.T) *dag.Graph {
   927  	g, err := dag.Parse(depsRules)
   928  	if err != nil {
   929  		t.Fatal(err)
   930  	}
   931  	return g
   932  }
   933  
   934  // TestStdlibLowercase tests that all standard library package names are
   935  // lowercase. See Issue 40065.
   936  func TestStdlibLowercase(t *testing.T) {
   937  	testenv.MustHaveSource(t)
   938  
   939  	ctxt := Default
   940  	all, err := listStdPkgs(ctxt.GOROOT)
   941  	if err != nil {
   942  		t.Fatal(err)
   943  	}
   944  
   945  	for _, pkgname := range all {
   946  		if strings.ToLower(pkgname) != pkgname {
   947  			t.Errorf("package %q should not use upper-case path", pkgname)
   948  		}
   949  	}
   950  }
   951  
   952  // TestFindImports tests that findImports works.  See #43249.
   953  func TestFindImports(t *testing.T) {
   954  	imports, err := findImports("go/build")
   955  	if err != nil {
   956  		t.Fatal(err)
   957  	}
   958  	t.Logf("go/build imports %q", imports)
   959  	want := []string{"bytes", "os", "path/filepath", "strings"}
   960  wantLoop:
   961  	for _, w := range want {
   962  		for _, imp := range imports {
   963  			if imp == w {
   964  				continue wantLoop
   965  			}
   966  		}
   967  		t.Errorf("expected to find %q in import list", w)
   968  	}
   969  }
   970  

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