Source file src/cmd/go/internal/modload/init.go

Documentation: cmd/go/internal/modload

     1  // Copyright 2018 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  package modload
     6  
     7  import (
     8  	"bytes"
     9  	"context"
    10  	"encoding/json"
    11  	"errors"
    12  	"fmt"
    13  	"internal/lazyregexp"
    14  	"io"
    15  	"os"
    16  	"path"
    17  	"path/filepath"
    18  	"slices"
    19  	"strconv"
    20  	"strings"
    21  	"sync"
    22  
    23  	"cmd/go/internal/base"
    24  	"cmd/go/internal/cfg"
    25  	"cmd/go/internal/fsys"
    26  	"cmd/go/internal/gover"
    27  	"cmd/go/internal/lockedfile"
    28  	"cmd/go/internal/modfetch"
    29  	"cmd/go/internal/search"
    30  
    31  	"golang.org/x/mod/modfile"
    32  	"golang.org/x/mod/module"
    33  )
    34  
    35  // Variables set by other packages.
    36  //
    37  // TODO(#40775): See if these can be plumbed as explicit parameters.
    38  var (
    39  	// RootMode determines whether a module root is needed.
    40  	RootMode Root
    41  
    42  	// ForceUseModules may be set to force modules to be enabled when
    43  	// GO111MODULE=auto or to report an error when GO111MODULE=off.
    44  	ForceUseModules bool
    45  
    46  	allowMissingModuleImports bool
    47  
    48  	// ExplicitWriteGoMod prevents LoadPackages, ListModules, and other functions
    49  	// from updating go.mod and go.sum or reporting errors when updates are
    50  	// needed. A package should set this if it would cause go.mod to be written
    51  	// multiple times (for example, 'go get' calls LoadPackages multiple times) or
    52  	// if it needs some other operation to be successful before go.mod and go.sum
    53  	// can be written (for example, 'go mod download' must download modules before
    54  	// adding sums to go.sum). Packages that set this are responsible for calling
    55  	// WriteGoMod explicitly.
    56  	ExplicitWriteGoMod bool
    57  )
    58  
    59  // Variables set in Init.
    60  var (
    61  	initialized bool
    62  
    63  	// These are primarily used to initialize the MainModules, and should be
    64  	// eventually superseded by them but are still used in cases where the module
    65  	// roots are required but MainModules hasn't been initialized yet. Set to
    66  	// the modRoots of the main modules.
    67  	// modRoots != nil implies len(modRoots) > 0
    68  	modRoots []string
    69  	gopath   string
    70  )
    71  
    72  // EnterModule resets MainModules and requirements to refer to just this one module.
    73  func EnterModule(ctx context.Context, enterModroot string) {
    74  	MainModules = nil // reset MainModules
    75  	requirements = nil
    76  	workFilePath = "" // Force module mode
    77  	modfetch.Reset()
    78  
    79  	modRoots = []string{enterModroot}
    80  	LoadModFile(ctx)
    81  }
    82  
    83  // Variable set in InitWorkfile
    84  var (
    85  	// Set to the path to the go.work file, or "" if workspace mode is disabled.
    86  	workFilePath string
    87  )
    88  
    89  type MainModuleSet struct {
    90  	// versions are the module.Version values of each of the main modules.
    91  	// For each of them, the Path fields are ordinary module paths and the Version
    92  	// fields are empty strings.
    93  	// versions is clipped (len=cap).
    94  	versions []module.Version
    95  
    96  	// modRoot maps each module in versions to its absolute filesystem path.
    97  	modRoot map[module.Version]string
    98  
    99  	// pathPrefix is the path prefix for packages in the module, without a trailing
   100  	// slash. For most modules, pathPrefix is just version.Path, but the
   101  	// standard-library module "std" has an empty prefix.
   102  	pathPrefix map[module.Version]string
   103  
   104  	// inGorootSrc caches whether modRoot is within GOROOT/src.
   105  	// The "std" module is special within GOROOT/src, but not otherwise.
   106  	inGorootSrc map[module.Version]bool
   107  
   108  	modFiles map[module.Version]*modfile.File
   109  
   110  	modContainingCWD module.Version
   111  
   112  	workFile *modfile.WorkFile
   113  
   114  	workFileReplaceMap map[module.Version]module.Version
   115  	// highest replaced version of each module path; empty string for wildcard-only replacements
   116  	highestReplaced map[string]string
   117  
   118  	indexMu sync.Mutex
   119  	indices map[module.Version]*modFileIndex
   120  }
   121  
   122  func (mms *MainModuleSet) PathPrefix(m module.Version) string {
   123  	return mms.pathPrefix[m]
   124  }
   125  
   126  // Versions returns the module.Version values of each of the main modules.
   127  // For each of them, the Path fields are ordinary module paths and the Version
   128  // fields are empty strings.
   129  // Callers should not modify the returned slice.
   130  func (mms *MainModuleSet) Versions() []module.Version {
   131  	if mms == nil {
   132  		return nil
   133  	}
   134  	return mms.versions
   135  }
   136  
   137  func (mms *MainModuleSet) Contains(path string) bool {
   138  	if mms == nil {
   139  		return false
   140  	}
   141  	for _, v := range mms.versions {
   142  		if v.Path == path {
   143  			return true
   144  		}
   145  	}
   146  	return false
   147  }
   148  
   149  func (mms *MainModuleSet) ModRoot(m module.Version) string {
   150  	if mms == nil {
   151  		return ""
   152  	}
   153  	return mms.modRoot[m]
   154  }
   155  
   156  func (mms *MainModuleSet) InGorootSrc(m module.Version) bool {
   157  	if mms == nil {
   158  		return false
   159  	}
   160  	return mms.inGorootSrc[m]
   161  }
   162  
   163  func (mms *MainModuleSet) mustGetSingleMainModule() module.Version {
   164  	if mms == nil || len(mms.versions) == 0 {
   165  		panic("internal error: mustGetSingleMainModule called in context with no main modules")
   166  	}
   167  	if len(mms.versions) != 1 {
   168  		if inWorkspaceMode() {
   169  			panic("internal error: mustGetSingleMainModule called in workspace mode")
   170  		} else {
   171  			panic("internal error: multiple main modules present outside of workspace mode")
   172  		}
   173  	}
   174  	return mms.versions[0]
   175  }
   176  
   177  func (mms *MainModuleSet) GetSingleIndexOrNil() *modFileIndex {
   178  	if mms == nil {
   179  		return nil
   180  	}
   181  	if len(mms.versions) == 0 {
   182  		return nil
   183  	}
   184  	return mms.indices[mms.mustGetSingleMainModule()]
   185  }
   186  
   187  func (mms *MainModuleSet) Index(m module.Version) *modFileIndex {
   188  	mms.indexMu.Lock()
   189  	defer mms.indexMu.Unlock()
   190  	return mms.indices[m]
   191  }
   192  
   193  func (mms *MainModuleSet) SetIndex(m module.Version, index *modFileIndex) {
   194  	mms.indexMu.Lock()
   195  	defer mms.indexMu.Unlock()
   196  	mms.indices[m] = index
   197  }
   198  
   199  func (mms *MainModuleSet) ModFile(m module.Version) *modfile.File {
   200  	return mms.modFiles[m]
   201  }
   202  
   203  func (mms *MainModuleSet) WorkFile() *modfile.WorkFile {
   204  	return mms.workFile
   205  }
   206  
   207  func (mms *MainModuleSet) Len() int {
   208  	if mms == nil {
   209  		return 0
   210  	}
   211  	return len(mms.versions)
   212  }
   213  
   214  // ModContainingCWD returns the main module containing the working directory,
   215  // or module.Version{} if none of the main modules contain the working
   216  // directory.
   217  func (mms *MainModuleSet) ModContainingCWD() module.Version {
   218  	return mms.modContainingCWD
   219  }
   220  
   221  func (mms *MainModuleSet) HighestReplaced() map[string]string {
   222  	return mms.highestReplaced
   223  }
   224  
   225  // GoVersion returns the go version set on the single module, in module mode,
   226  // or the go.work file in workspace mode.
   227  func (mms *MainModuleSet) GoVersion() string {
   228  	if inWorkspaceMode() {
   229  		return gover.FromGoWork(mms.workFile)
   230  	}
   231  	if mms != nil && len(mms.versions) == 1 {
   232  		f := mms.ModFile(mms.mustGetSingleMainModule())
   233  		if f == nil {
   234  			// Special case: we are outside a module, like 'go run x.go'.
   235  			// Assume the local Go version.
   236  			// TODO(#49228): Clean this up; see loadModFile.
   237  			return gover.Local()
   238  		}
   239  		return gover.FromGoMod(f)
   240  	}
   241  	return gover.DefaultGoModVersion
   242  }
   243  
   244  // Toolchain returns the toolchain set on the single module, in module mode,
   245  // or the go.work file in workspace mode.
   246  func (mms *MainModuleSet) Toolchain() string {
   247  	if inWorkspaceMode() {
   248  		if mms.workFile != nil && mms.workFile.Toolchain != nil {
   249  			return mms.workFile.Toolchain.Name
   250  		}
   251  		return "go" + mms.GoVersion()
   252  	}
   253  	if mms != nil && len(mms.versions) == 1 {
   254  		f := mms.ModFile(mms.mustGetSingleMainModule())
   255  		if f == nil {
   256  			// Special case: we are outside a module, like 'go run x.go'.
   257  			// Assume the local Go version.
   258  			// TODO(#49228): Clean this up; see loadModFile.
   259  			return gover.LocalToolchain()
   260  		}
   261  		if f.Toolchain != nil {
   262  			return f.Toolchain.Name
   263  		}
   264  	}
   265  	return "go" + mms.GoVersion()
   266  }
   267  
   268  func (mms *MainModuleSet) WorkFileReplaceMap() map[module.Version]module.Version {
   269  	return mms.workFileReplaceMap
   270  }
   271  
   272  var MainModules *MainModuleSet
   273  
   274  type Root int
   275  
   276  const (
   277  	// AutoRoot is the default for most commands. modload.Init will look for
   278  	// a go.mod file in the current directory or any parent. If none is found,
   279  	// modules may be disabled (GO111MODULE=auto) or commands may run in a
   280  	// limited module mode.
   281  	AutoRoot Root = iota
   282  
   283  	// NoRoot is used for commands that run in module mode and ignore any go.mod
   284  	// file the current directory or in parent directories.
   285  	NoRoot
   286  
   287  	// NeedRoot is used for commands that must run in module mode and don't
   288  	// make sense without a main module.
   289  	NeedRoot
   290  )
   291  
   292  // ModFile returns the parsed go.mod file.
   293  //
   294  // Note that after calling LoadPackages or LoadModGraph,
   295  // the require statements in the modfile.File are no longer
   296  // the source of truth and will be ignored: edits made directly
   297  // will be lost at the next call to WriteGoMod.
   298  // To make permanent changes to the require statements
   299  // in go.mod, edit it before loading.
   300  func ModFile() *modfile.File {
   301  	Init()
   302  	modFile := MainModules.ModFile(MainModules.mustGetSingleMainModule())
   303  	if modFile == nil {
   304  		die()
   305  	}
   306  	return modFile
   307  }
   308  
   309  func BinDir() string {
   310  	Init()
   311  	if cfg.GOBIN != "" {
   312  		return cfg.GOBIN
   313  	}
   314  	if gopath == "" {
   315  		return ""
   316  	}
   317  	return filepath.Join(gopath, "bin")
   318  }
   319  
   320  // InitWorkfile initializes the workFilePath variable for commands that
   321  // operate in workspace mode. It should not be called by other commands,
   322  // for example 'go mod tidy', that don't operate in workspace mode.
   323  func InitWorkfile() {
   324  	workFilePath = FindGoWork(base.Cwd())
   325  }
   326  
   327  // FindGoWork returns the name of the go.work file for this command,
   328  // or the empty string if there isn't one.
   329  // Most code should use Init and Enabled rather than use this directly.
   330  // It is exported mainly for Go toolchain switching, which must process
   331  // the go.work very early at startup.
   332  func FindGoWork(wd string) string {
   333  	if RootMode == NoRoot {
   334  		return ""
   335  	}
   336  
   337  	switch gowork := cfg.Getenv("GOWORK"); gowork {
   338  	case "off":
   339  		return ""
   340  	case "", "auto":
   341  		return findWorkspaceFile(wd)
   342  	default:
   343  		if !filepath.IsAbs(gowork) {
   344  			base.Fatalf("go: invalid GOWORK: not an absolute path")
   345  		}
   346  		return gowork
   347  	}
   348  }
   349  
   350  // WorkFilePath returns the absolute path of the go.work file, or "" if not in
   351  // workspace mode. WorkFilePath must be called after InitWorkfile.
   352  func WorkFilePath() string {
   353  	return workFilePath
   354  }
   355  
   356  // Reset clears all the initialized, cached state about the use of modules,
   357  // so that we can start over.
   358  func Reset() {
   359  	initialized = false
   360  	ForceUseModules = false
   361  	RootMode = 0
   362  	modRoots = nil
   363  	cfg.ModulesEnabled = false
   364  	MainModules = nil
   365  	requirements = nil
   366  	workFilePath = ""
   367  	modfetch.Reset()
   368  }
   369  
   370  // Init determines whether module mode is enabled, locates the root of the
   371  // current module (if any), sets environment variables for Git subprocesses, and
   372  // configures the cfg, codehost, load, modfetch, and search packages for use
   373  // with modules.
   374  func Init() {
   375  	if initialized {
   376  		return
   377  	}
   378  	initialized = true
   379  
   380  	// Keep in sync with WillBeEnabled. We perform extra validation here, and
   381  	// there are lots of diagnostics and side effects, so we can't use
   382  	// WillBeEnabled directly.
   383  	var mustUseModules bool
   384  	env := cfg.Getenv("GO111MODULE")
   385  	switch env {
   386  	default:
   387  		base.Fatalf("go: unknown environment setting GO111MODULE=%s", env)
   388  	case "auto":
   389  		mustUseModules = ForceUseModules
   390  	case "on", "":
   391  		mustUseModules = true
   392  	case "off":
   393  		if ForceUseModules {
   394  			base.Fatalf("go: modules disabled by GO111MODULE=off; see 'go help modules'")
   395  		}
   396  		mustUseModules = false
   397  		return
   398  	}
   399  
   400  	if err := fsys.Init(base.Cwd()); err != nil {
   401  		base.Fatal(err)
   402  	}
   403  
   404  	// Disable any prompting for passwords by Git.
   405  	// Only has an effect for 2.3.0 or later, but avoiding
   406  	// the prompt in earlier versions is just too hard.
   407  	// If user has explicitly set GIT_TERMINAL_PROMPT=1, keep
   408  	// prompting.
   409  	// See golang.org/issue/9341 and golang.org/issue/12706.
   410  	if os.Getenv("GIT_TERMINAL_PROMPT") == "" {
   411  		os.Setenv("GIT_TERMINAL_PROMPT", "0")
   412  	}
   413  
   414  	// Disable any ssh connection pooling by Git.
   415  	// If a Git subprocess forks a child into the background to cache a new connection,
   416  	// that child keeps stdout/stderr open. After the Git subprocess exits,
   417  	// os/exec expects to be able to read from the stdout/stderr pipe
   418  	// until EOF to get all the data that the Git subprocess wrote before exiting.
   419  	// The EOF doesn't come until the child exits too, because the child
   420  	// is holding the write end of the pipe.
   421  	// This is unfortunate, but it has come up at least twice
   422  	// (see golang.org/issue/13453 and golang.org/issue/16104)
   423  	// and confuses users when it does.
   424  	// If the user has explicitly set GIT_SSH or GIT_SSH_COMMAND,
   425  	// assume they know what they are doing and don't step on it.
   426  	// But default to turning off ControlMaster.
   427  	if os.Getenv("GIT_SSH") == "" && os.Getenv("GIT_SSH_COMMAND") == "" {
   428  		os.Setenv("GIT_SSH_COMMAND", "ssh -o ControlMaster=no -o BatchMode=yes")
   429  	}
   430  
   431  	if os.Getenv("GCM_INTERACTIVE") == "" {
   432  		os.Setenv("GCM_INTERACTIVE", "never")
   433  	}
   434  	if modRoots != nil {
   435  		// modRoot set before Init was called ("go mod init" does this).
   436  		// No need to search for go.mod.
   437  	} else if RootMode == NoRoot {
   438  		if cfg.ModFile != "" && !base.InGOFLAGS("-modfile") {
   439  			base.Fatalf("go: -modfile cannot be used with commands that ignore the current module")
   440  		}
   441  		modRoots = nil
   442  	} else if workFilePath != "" {
   443  		// We're in workspace mode, which implies module mode.
   444  		if cfg.ModFile != "" {
   445  			base.Fatalf("go: -modfile cannot be used in workspace mode")
   446  		}
   447  	} else {
   448  		if modRoot := findModuleRoot(base.Cwd()); modRoot == "" {
   449  			if cfg.ModFile != "" {
   450  				base.Fatalf("go: cannot find main module, but -modfile was set.\n\t-modfile cannot be used to set the module root directory.")
   451  			}
   452  			if RootMode == NeedRoot {
   453  				base.Fatal(ErrNoModRoot)
   454  			}
   455  			if !mustUseModules {
   456  				// GO111MODULE is 'auto', and we can't find a module root.
   457  				// Stay in GOPATH mode.
   458  				return
   459  			}
   460  		} else if search.InDir(modRoot, os.TempDir()) == "." {
   461  			// If you create /tmp/go.mod for experimenting,
   462  			// then any tests that create work directories under /tmp
   463  			// will find it and get modules when they're not expecting them.
   464  			// It's a bit of a peculiar thing to disallow but quite mysterious
   465  			// when it happens. See golang.org/issue/26708.
   466  			fmt.Fprintf(os.Stderr, "go: warning: ignoring go.mod in system temp root %v\n", os.TempDir())
   467  			if RootMode == NeedRoot {
   468  				base.Fatal(ErrNoModRoot)
   469  			}
   470  			if !mustUseModules {
   471  				return
   472  			}
   473  		} else {
   474  			modRoots = []string{modRoot}
   475  		}
   476  	}
   477  	if cfg.ModFile != "" && !strings.HasSuffix(cfg.ModFile, ".mod") {
   478  		base.Fatalf("go: -modfile=%s: file does not have .mod extension", cfg.ModFile)
   479  	}
   480  
   481  	// We're in module mode. Set any global variables that need to be set.
   482  	cfg.ModulesEnabled = true
   483  	setDefaultBuildMod()
   484  	list := filepath.SplitList(cfg.BuildContext.GOPATH)
   485  	if len(list) > 0 && list[0] != "" {
   486  		gopath = list[0]
   487  		if _, err := fsys.Stat(filepath.Join(gopath, "go.mod")); err == nil {
   488  			fmt.Fprintf(os.Stderr, "go: warning: ignoring go.mod in $GOPATH %v\n", gopath)
   489  			if RootMode == NeedRoot {
   490  				base.Fatal(ErrNoModRoot)
   491  			}
   492  			if !mustUseModules {
   493  				return
   494  			}
   495  		}
   496  	}
   497  }
   498  
   499  // WillBeEnabled checks whether modules should be enabled but does not
   500  // initialize modules by installing hooks. If Init has already been called,
   501  // WillBeEnabled returns the same result as Enabled.
   502  //
   503  // This function is needed to break a cycle. The main package needs to know
   504  // whether modules are enabled in order to install the module or GOPATH version
   505  // of 'go get', but Init reads the -modfile flag in 'go get', so it shouldn't
   506  // be called until the command is installed and flags are parsed. Instead of
   507  // calling Init and Enabled, the main package can call this function.
   508  func WillBeEnabled() bool {
   509  	if modRoots != nil || cfg.ModulesEnabled {
   510  		// Already enabled.
   511  		return true
   512  	}
   513  	if initialized {
   514  		// Initialized, not enabled.
   515  		return false
   516  	}
   517  
   518  	// Keep in sync with Init. Init does extra validation and prints warnings or
   519  	// exits, so it can't call this function directly.
   520  	env := cfg.Getenv("GO111MODULE")
   521  	switch env {
   522  	case "on", "":
   523  		return true
   524  	case "auto":
   525  		break
   526  	default:
   527  		return false
   528  	}
   529  
   530  	return FindGoMod(base.Cwd()) != ""
   531  }
   532  
   533  // FindGoMod returns the name of the go.mod file for this command,
   534  // or the empty string if there isn't one.
   535  // Most code should use Init and Enabled rather than use this directly.
   536  // It is exported mainly for Go toolchain switching, which must process
   537  // the go.mod very early at startup.
   538  func FindGoMod(wd string) string {
   539  	modRoot := findModuleRoot(wd)
   540  	if modRoot == "" {
   541  		// GO111MODULE is 'auto', and we can't find a module root.
   542  		// Stay in GOPATH mode.
   543  		return ""
   544  	}
   545  	if search.InDir(modRoot, os.TempDir()) == "." {
   546  		// If you create /tmp/go.mod for experimenting,
   547  		// then any tests that create work directories under /tmp
   548  		// will find it and get modules when they're not expecting them.
   549  		// It's a bit of a peculiar thing to disallow but quite mysterious
   550  		// when it happens. See golang.org/issue/26708.
   551  		return ""
   552  	}
   553  	return filepath.Join(modRoot, "go.mod")
   554  }
   555  
   556  // Enabled reports whether modules are (or must be) enabled.
   557  // If modules are enabled but there is no main module, Enabled returns true
   558  // and then the first use of module information will call die
   559  // (usually through MustModRoot).
   560  func Enabled() bool {
   561  	Init()
   562  	return modRoots != nil || cfg.ModulesEnabled
   563  }
   564  
   565  func VendorDir() string {
   566  	if inWorkspaceMode() {
   567  		return filepath.Join(filepath.Dir(WorkFilePath()), "vendor")
   568  	}
   569  	// Even if -mod=vendor, we could be operating with no mod root (and thus no
   570  	// vendor directory). As long as there are no dependencies that is expected
   571  	// to work. See script/vendor_outside_module.txt.
   572  	modRoot := MainModules.ModRoot(MainModules.mustGetSingleMainModule())
   573  	if modRoot == "" {
   574  		panic("vendor directory does not exist when in single module mode outside of a module")
   575  	}
   576  	return filepath.Join(modRoot, "vendor")
   577  }
   578  
   579  func inWorkspaceMode() bool {
   580  	if !initialized {
   581  		panic("inWorkspaceMode called before modload.Init called")
   582  	}
   583  	if !Enabled() {
   584  		return false
   585  	}
   586  	return workFilePath != ""
   587  }
   588  
   589  // HasModRoot reports whether a main module is present.
   590  // HasModRoot may return false even if Enabled returns true: for example, 'get'
   591  // does not require a main module.
   592  func HasModRoot() bool {
   593  	Init()
   594  	return modRoots != nil
   595  }
   596  
   597  // MustHaveModRoot checks that a main module or main modules are present,
   598  // and calls base.Fatalf if there are no main modules.
   599  func MustHaveModRoot() {
   600  	Init()
   601  	if !HasModRoot() {
   602  		die()
   603  	}
   604  }
   605  
   606  // ModFilePath returns the path that would be used for the go.mod
   607  // file, if in module mode. ModFilePath calls base.Fatalf if there is no main
   608  // module, even if -modfile is set.
   609  func ModFilePath() string {
   610  	MustHaveModRoot()
   611  	return modFilePath(findModuleRoot(base.Cwd()))
   612  }
   613  
   614  func modFilePath(modRoot string) string {
   615  	if cfg.ModFile != "" {
   616  		return cfg.ModFile
   617  	}
   618  	return filepath.Join(modRoot, "go.mod")
   619  }
   620  
   621  func die() {
   622  	if cfg.Getenv("GO111MODULE") == "off" {
   623  		base.Fatalf("go: modules disabled by GO111MODULE=off; see 'go help modules'")
   624  	}
   625  	if inWorkspaceMode() {
   626  		base.Fatalf("go: no modules were found in the current workspace; see 'go help work'")
   627  	}
   628  	if dir, name := findAltConfig(base.Cwd()); dir != "" {
   629  		rel, err := filepath.Rel(base.Cwd(), dir)
   630  		if err != nil {
   631  			rel = dir
   632  		}
   633  		cdCmd := ""
   634  		if rel != "." {
   635  			cdCmd = fmt.Sprintf("cd %s && ", rel)
   636  		}
   637  		base.Fatalf("go: cannot find main module, but found %s in %s\n\tto create a module there, run:\n\t%sgo mod init", name, dir, cdCmd)
   638  	}
   639  	base.Fatal(ErrNoModRoot)
   640  }
   641  
   642  var ErrNoModRoot = errors.New("go.mod file not found in current directory or any parent directory; see 'go help modules'")
   643  
   644  type goModDirtyError struct{}
   645  
   646  func (goModDirtyError) Error() string {
   647  	if cfg.BuildModExplicit {
   648  		return fmt.Sprintf("updates to go.mod needed, disabled by -mod=%v; to update it:\n\tgo mod tidy", cfg.BuildMod)
   649  	}
   650  	if cfg.BuildModReason != "" {
   651  		return fmt.Sprintf("updates to go.mod needed, disabled by -mod=%s\n\t(%s)\n\tto update it:\n\tgo mod tidy", cfg.BuildMod, cfg.BuildModReason)
   652  	}
   653  	return "updates to go.mod needed; to update it:\n\tgo mod tidy"
   654  }
   655  
   656  var errGoModDirty error = goModDirtyError{}
   657  
   658  func loadWorkFile(path string) (workFile *modfile.WorkFile, modRoots []string, err error) {
   659  	workDir := filepath.Dir(path)
   660  	wf, err := ReadWorkFile(path)
   661  	if err != nil {
   662  		return nil, nil, err
   663  	}
   664  	seen := map[string]bool{}
   665  	for _, d := range wf.Use {
   666  		modRoot := d.Path
   667  		if !filepath.IsAbs(modRoot) {
   668  			modRoot = filepath.Join(workDir, modRoot)
   669  		}
   670  
   671  		if seen[modRoot] {
   672  			return nil, nil, fmt.Errorf("path %s appears multiple times in workspace", modRoot)
   673  		}
   674  		seen[modRoot] = true
   675  		modRoots = append(modRoots, modRoot)
   676  	}
   677  
   678  	return wf, modRoots, nil
   679  }
   680  
   681  // ReadWorkFile reads and parses the go.work file at the given path.
   682  func ReadWorkFile(path string) (*modfile.WorkFile, error) {
   683  	workData, err := os.ReadFile(path)
   684  	if err != nil {
   685  		return nil, err
   686  	}
   687  
   688  	f, err := modfile.ParseWork(path, workData, nil)
   689  	if err != nil {
   690  		return nil, err
   691  	}
   692  	if f.Go != nil && gover.Compare(f.Go.Version, gover.Local()) > 0 && cfg.CmdName != "work edit" {
   693  		base.Fatal(&gover.TooNewError{What: base.ShortPath(path), GoVersion: f.Go.Version})
   694  	}
   695  	return f, nil
   696  }
   697  
   698  // WriteWorkFile cleans and writes out the go.work file to the given path.
   699  func WriteWorkFile(path string, wf *modfile.WorkFile) error {
   700  	wf.SortBlocks()
   701  	wf.Cleanup()
   702  	out := modfile.Format(wf.Syntax)
   703  
   704  	return os.WriteFile(path, out, 0666)
   705  }
   706  
   707  // UpdateWorkGoVersion updates the go line in wf to be at least goVers,
   708  // reporting whether it changed the file.
   709  func UpdateWorkGoVersion(wf *modfile.WorkFile, goVers string) (changed bool) {
   710  	old := gover.FromGoWork(wf)
   711  	if gover.Compare(old, goVers) >= 0 {
   712  		return false
   713  	}
   714  
   715  	wf.AddGoStmt(goVers)
   716  
   717  	// We wrote a new go line. For reproducibility,
   718  	// if the toolchain running right now is newer than the new toolchain line,
   719  	// update the toolchain line to record the newer toolchain.
   720  	// The user never sets the toolchain explicitly in a 'go work' command,
   721  	// so this is only happening as a result of a go or toolchain line found
   722  	// in a module.
   723  	// If the toolchain running right now is a dev toolchain (like "go1.21")
   724  	// writing 'toolchain go1.21' will not be useful, since that's not an actual
   725  	// toolchain you can download and run. In that case fall back to at least
   726  	// checking that the toolchain is new enough for the Go version.
   727  	toolchain := "go" + old
   728  	if wf.Toolchain != nil {
   729  		toolchain = wf.Toolchain.Name
   730  	}
   731  	if gover.IsLang(gover.Local()) {
   732  		toolchain = gover.ToolchainMax(toolchain, "go"+goVers)
   733  	} else {
   734  		toolchain = gover.ToolchainMax(toolchain, "go"+gover.Local())
   735  	}
   736  
   737  	// Drop the toolchain line if it is implied by the go line
   738  	// or if it is asking for a toolchain older than Go 1.21,
   739  	// which will not understand the toolchain line.
   740  	if toolchain == "go"+goVers || gover.Compare(gover.FromToolchain(toolchain), gover.GoStrictVersion) < 0 {
   741  		wf.DropToolchainStmt()
   742  	} else {
   743  		wf.AddToolchainStmt(toolchain)
   744  	}
   745  	return true
   746  }
   747  
   748  // UpdateWorkFile updates comments on directory directives in the go.work
   749  // file to include the associated module path.
   750  func UpdateWorkFile(wf *modfile.WorkFile) {
   751  	missingModulePaths := map[string]string{} // module directory listed in file -> abspath modroot
   752  
   753  	for _, d := range wf.Use {
   754  		if d.Path == "" {
   755  			continue // d is marked for deletion.
   756  		}
   757  		modRoot := d.Path
   758  		if d.ModulePath == "" {
   759  			missingModulePaths[d.Path] = modRoot
   760  		}
   761  	}
   762  
   763  	// Clean up and annotate directories.
   764  	// TODO(matloob): update x/mod to actually add module paths.
   765  	for moddir, absmodroot := range missingModulePaths {
   766  		_, f, err := ReadModFile(filepath.Join(absmodroot, "go.mod"), nil)
   767  		if err != nil {
   768  			continue // Error will be reported if modules are loaded.
   769  		}
   770  		wf.AddUse(moddir, f.Module.Mod.Path)
   771  	}
   772  }
   773  
   774  // LoadModFile sets Target and, if there is a main module, parses the initial
   775  // build list from its go.mod file.
   776  //
   777  // LoadModFile may make changes in memory, like adding a go directive and
   778  // ensuring requirements are consistent. The caller is responsible for ensuring
   779  // those changes are written to disk by calling LoadPackages or ListModules
   780  // (unless ExplicitWriteGoMod is set) or by calling WriteGoMod directly.
   781  //
   782  // As a side-effect, LoadModFile may change cfg.BuildMod to "vendor" if
   783  // -mod wasn't set explicitly and automatic vendoring should be enabled.
   784  //
   785  // If LoadModFile or CreateModFile has already been called, LoadModFile returns
   786  // the existing in-memory requirements (rather than re-reading them from disk).
   787  //
   788  // LoadModFile checks the roots of the module graph for consistency with each
   789  // other, but unlike LoadModGraph does not load the full module graph or check
   790  // it for global consistency. Most callers outside of the modload package should
   791  // use LoadModGraph instead.
   792  func LoadModFile(ctx context.Context) *Requirements {
   793  	rs, err := loadModFile(ctx, nil)
   794  	if err != nil {
   795  		base.Fatal(err)
   796  	}
   797  	return rs
   798  }
   799  
   800  func loadModFile(ctx context.Context, opts *PackageOpts) (*Requirements, error) {
   801  	if requirements != nil {
   802  		return requirements, nil
   803  	}
   804  
   805  	Init()
   806  	var workFile *modfile.WorkFile
   807  	if inWorkspaceMode() {
   808  		var err error
   809  		workFile, modRoots, err = loadWorkFile(workFilePath)
   810  		if err != nil {
   811  			return nil, fmt.Errorf("reading go.work: %w", err)
   812  		}
   813  		for _, modRoot := range modRoots {
   814  			sumFile := strings.TrimSuffix(modFilePath(modRoot), ".mod") + ".sum"
   815  			modfetch.WorkspaceGoSumFiles = append(modfetch.WorkspaceGoSumFiles, sumFile)
   816  		}
   817  		modfetch.GoSumFile = workFilePath + ".sum"
   818  	} else if len(modRoots) == 0 {
   819  		// We're in module mode, but not inside a module.
   820  		//
   821  		// Commands like 'go build', 'go run', 'go list' have no go.mod file to
   822  		// read or write. They would need to find and download the latest versions
   823  		// of a potentially large number of modules with no way to save version
   824  		// information. We can succeed slowly (but not reproducibly), but that's
   825  		// not usually a good experience.
   826  		//
   827  		// Instead, we forbid resolving import paths to modules other than std and
   828  		// cmd. Users may still build packages specified with .go files on the
   829  		// command line, but they'll see an error if those files import anything
   830  		// outside std.
   831  		//
   832  		// This can be overridden by calling AllowMissingModuleImports.
   833  		// For example, 'go get' does this, since it is expected to resolve paths.
   834  		//
   835  		// See golang.org/issue/32027.
   836  	} else {
   837  		modfetch.GoSumFile = strings.TrimSuffix(modFilePath(modRoots[0]), ".mod") + ".sum"
   838  	}
   839  	if len(modRoots) == 0 {
   840  		// TODO(#49228): Instead of creating a fake module with an empty modroot,
   841  		// make MainModules.Len() == 0 mean that we're in module mode but not inside
   842  		// any module.
   843  		mainModule := module.Version{Path: "command-line-arguments"}
   844  		MainModules = makeMainModules([]module.Version{mainModule}, []string{""}, []*modfile.File{nil}, []*modFileIndex{nil}, nil)
   845  		var (
   846  			goVersion string
   847  			pruning   modPruning
   848  			roots     []module.Version
   849  			direct    = map[string]bool{"go": true}
   850  		)
   851  		if inWorkspaceMode() {
   852  			// Since we are in a workspace, the Go version for the synthetic
   853  			// "command-line-arguments" module must not exceed the Go version
   854  			// for the workspace.
   855  			goVersion = MainModules.GoVersion()
   856  			pruning = workspace
   857  			roots = []module.Version{
   858  				mainModule,
   859  				{Path: "go", Version: goVersion},
   860  				{Path: "toolchain", Version: gover.LocalToolchain()},
   861  			}
   862  		} else {
   863  			goVersion = gover.Local()
   864  			pruning = pruningForGoVersion(goVersion)
   865  			roots = []module.Version{
   866  				{Path: "go", Version: goVersion},
   867  				{Path: "toolchain", Version: gover.LocalToolchain()},
   868  			}
   869  		}
   870  		rawGoVersion.Store(mainModule, goVersion)
   871  		requirements = newRequirements(pruning, roots, direct)
   872  		if cfg.BuildMod == "vendor" {
   873  			// For issue 56536: Some users may have GOFLAGS=-mod=vendor set.
   874  			// Make sure it behaves as though the fake module is vendored
   875  			// with no dependencies.
   876  			requirements.initVendor(nil)
   877  		}
   878  		return requirements, nil
   879  	}
   880  
   881  	var modFiles []*modfile.File
   882  	var mainModules []module.Version
   883  	var indices []*modFileIndex
   884  	var errs []error
   885  	for _, modroot := range modRoots {
   886  		gomod := modFilePath(modroot)
   887  		var fixed bool
   888  		data, f, err := ReadModFile(gomod, fixVersion(ctx, &fixed))
   889  		if err != nil {
   890  			if inWorkspaceMode() {
   891  				if tooNew, ok := err.(*gover.TooNewError); ok && !strings.HasPrefix(cfg.CmdName, "work ") {
   892  					// Switching to a newer toolchain won't help - the go.work has the wrong version.
   893  					// Report this more specific error, unless we are a command like 'go work use'
   894  					// or 'go work sync', which will fix the problem after the caller sees the TooNewError
   895  					// and switches to a newer toolchain.
   896  					err = errWorkTooOld(gomod, workFile, tooNew.GoVersion)
   897  				} else {
   898  					err = fmt.Errorf("cannot load module %s listed in go.work file: %w",
   899  						base.ShortPath(filepath.Dir(gomod)), err)
   900  				}
   901  			}
   902  			errs = append(errs, err)
   903  			continue
   904  		}
   905  		if inWorkspaceMode() && !strings.HasPrefix(cfg.CmdName, "work ") {
   906  			// Refuse to use workspace if its go version is too old.
   907  			// Disable this check if we are a workspace command like work use or work sync,
   908  			// which will fix the problem.
   909  			mv := gover.FromGoMod(f)
   910  			wv := gover.FromGoWork(workFile)
   911  			if gover.Compare(mv, wv) > 0 && gover.Compare(mv, gover.GoStrictVersion) >= 0 {
   912  				errs = append(errs, errWorkTooOld(gomod, workFile, mv))
   913  				continue
   914  			}
   915  		}
   916  
   917  		modFiles = append(modFiles, f)
   918  		mainModule := f.Module.Mod
   919  		mainModules = append(mainModules, mainModule)
   920  		indices = append(indices, indexModFile(data, f, mainModule, fixed))
   921  
   922  		if err := module.CheckImportPath(f.Module.Mod.Path); err != nil {
   923  			if pathErr, ok := err.(*module.InvalidPathError); ok {
   924  				pathErr.Kind = "module"
   925  			}
   926  			errs = append(errs, err)
   927  		}
   928  	}
   929  	if len(errs) > 0 {
   930  		return nil, errors.Join(errs...)
   931  	}
   932  
   933  	MainModules = makeMainModules(mainModules, modRoots, modFiles, indices, workFile)
   934  	setDefaultBuildMod() // possibly enable automatic vendoring
   935  	rs := requirementsFromModFiles(ctx, workFile, modFiles, opts)
   936  
   937  	if cfg.BuildMod == "vendor" {
   938  		readVendorList(VendorDir())
   939  		var indexes []*modFileIndex
   940  		var modFiles []*modfile.File
   941  		var modRoots []string
   942  		for _, m := range MainModules.Versions() {
   943  			indexes = append(indexes, MainModules.Index(m))
   944  			modFiles = append(modFiles, MainModules.ModFile(m))
   945  			modRoots = append(modRoots, MainModules.ModRoot(m))
   946  		}
   947  		checkVendorConsistency(indexes, modFiles, modRoots)
   948  		rs.initVendor(vendorList)
   949  	}
   950  
   951  	if inWorkspaceMode() {
   952  		// We don't need to update the mod file so return early.
   953  		requirements = rs
   954  		return rs, nil
   955  	}
   956  
   957  	mainModule := MainModules.mustGetSingleMainModule()
   958  
   959  	if rs.hasRedundantRoot() {
   960  		// If any module path appears more than once in the roots, we know that the
   961  		// go.mod file needs to be updated even though we have not yet loaded any
   962  		// transitive dependencies.
   963  		var err error
   964  		rs, err = updateRoots(ctx, rs.direct, rs, nil, nil, false)
   965  		if err != nil {
   966  			return nil, err
   967  		}
   968  	}
   969  
   970  	if MainModules.Index(mainModule).goVersion == "" && rs.pruning != workspace {
   971  		// TODO(#45551): Do something more principled instead of checking
   972  		// cfg.CmdName directly here.
   973  		if cfg.BuildMod == "mod" && cfg.CmdName != "mod graph" && cfg.CmdName != "mod why" {
   974  			// go line is missing from go.mod; add one there and add to derived requirements.
   975  			v := gover.Local()
   976  			if opts != nil && opts.TidyGoVersion != "" {
   977  				v = opts.TidyGoVersion
   978  			}
   979  			addGoStmt(MainModules.ModFile(mainModule), mainModule, v)
   980  			rs = overrideRoots(ctx, rs, []module.Version{{Path: "go", Version: v}})
   981  
   982  			// We need to add a 'go' version to the go.mod file, but we must assume
   983  			// that its existing contents match something between Go 1.11 and 1.16.
   984  			// Go 1.11 through 1.16 do not support graph pruning, but the latest Go
   985  			// version uses a pruned module graph — so we need to convert the
   986  			// requirements to support pruning.
   987  			if gover.Compare(v, gover.ExplicitIndirectVersion) >= 0 {
   988  				var err error
   989  				rs, err = convertPruning(ctx, rs, pruned)
   990  				if err != nil {
   991  					return nil, err
   992  				}
   993  			}
   994  		} else {
   995  			rawGoVersion.Store(mainModule, gover.DefaultGoModVersion)
   996  		}
   997  	}
   998  
   999  	requirements = rs
  1000  	return requirements, nil
  1001  }
  1002  
  1003  func errWorkTooOld(gomod string, wf *modfile.WorkFile, goVers string) error {
  1004  	return fmt.Errorf("module %s listed in go.work file requires go >= %s, but go.work lists go %s; to update it:\n\tgo work use",
  1005  		base.ShortPath(filepath.Dir(gomod)), goVers, gover.FromGoWork(wf))
  1006  }
  1007  
  1008  // CreateModFile initializes a new module by creating a go.mod file.
  1009  //
  1010  // If modPath is empty, CreateModFile will attempt to infer the path from the
  1011  // directory location within GOPATH.
  1012  //
  1013  // If a vendoring configuration file is present, CreateModFile will attempt to
  1014  // translate it to go.mod directives. The resulting build list may not be
  1015  // exactly the same as in the legacy configuration (for example, we can't get
  1016  // packages at multiple versions from the same module).
  1017  func CreateModFile(ctx context.Context, modPath string) {
  1018  	modRoot := base.Cwd()
  1019  	modRoots = []string{modRoot}
  1020  	Init()
  1021  	modFilePath := modFilePath(modRoot)
  1022  	if _, err := fsys.Stat(modFilePath); err == nil {
  1023  		base.Fatalf("go: %s already exists", modFilePath)
  1024  	}
  1025  
  1026  	if modPath == "" {
  1027  		var err error
  1028  		modPath, err = findModulePath(modRoot)
  1029  		if err != nil {
  1030  			base.Fatal(err)
  1031  		}
  1032  	} else if err := module.CheckImportPath(modPath); err != nil {
  1033  		if pathErr, ok := err.(*module.InvalidPathError); ok {
  1034  			pathErr.Kind = "module"
  1035  			// Same as build.IsLocalPath()
  1036  			if pathErr.Path == "." || pathErr.Path == ".." ||
  1037  				strings.HasPrefix(pathErr.Path, "./") || strings.HasPrefix(pathErr.Path, "../") {
  1038  				pathErr.Err = errors.New("is a local import path")
  1039  			}
  1040  		}
  1041  		base.Fatal(err)
  1042  	} else if _, _, ok := module.SplitPathVersion(modPath); !ok {
  1043  		if strings.HasPrefix(modPath, "gopkg.in/") {
  1044  			invalidMajorVersionMsg := fmt.Errorf("module paths beginning with gopkg.in/ must always have a major version suffix in the form of .vN:\n\tgo mod init %s", suggestGopkgIn(modPath))
  1045  			base.Fatalf(`go: invalid module path "%v": %v`, modPath, invalidMajorVersionMsg)
  1046  		}
  1047  		invalidMajorVersionMsg := fmt.Errorf("major version suffixes must be in the form of /vN and are only allowed for v2 or later:\n\tgo mod init %s", suggestModulePath(modPath))
  1048  		base.Fatalf(`go: invalid module path "%v": %v`, modPath, invalidMajorVersionMsg)
  1049  	}
  1050  
  1051  	fmt.Fprintf(os.Stderr, "go: creating new go.mod: module %s\n", modPath)
  1052  	modFile := new(modfile.File)
  1053  	modFile.AddModuleStmt(modPath)
  1054  	MainModules = makeMainModules([]module.Version{modFile.Module.Mod}, []string{modRoot}, []*modfile.File{modFile}, []*modFileIndex{nil}, nil)
  1055  	addGoStmt(modFile, modFile.Module.Mod, gover.Local()) // Add the go directive before converted module requirements.
  1056  
  1057  	rs := requirementsFromModFiles(ctx, nil, []*modfile.File{modFile}, nil)
  1058  	rs, err := updateRoots(ctx, rs.direct, rs, nil, nil, false)
  1059  	if err != nil {
  1060  		base.Fatal(err)
  1061  	}
  1062  	requirements = rs
  1063  	if err := commitRequirements(ctx, WriteOpts{}); err != nil {
  1064  		base.Fatal(err)
  1065  	}
  1066  
  1067  	// Suggest running 'go mod tidy' unless the project is empty. Even if we
  1068  	// imported all the correct requirements above, we're probably missing
  1069  	// some sums, so the next build command in -mod=readonly will likely fail.
  1070  	//
  1071  	// We look for non-hidden .go files or subdirectories to determine whether
  1072  	// this is an existing project. Walking the tree for packages would be more
  1073  	// accurate, but could take much longer.
  1074  	empty := true
  1075  	files, _ := os.ReadDir(modRoot)
  1076  	for _, f := range files {
  1077  		name := f.Name()
  1078  		if strings.HasPrefix(name, ".") || strings.HasPrefix(name, "_") {
  1079  			continue
  1080  		}
  1081  		if strings.HasSuffix(name, ".go") || f.IsDir() {
  1082  			empty = false
  1083  			break
  1084  		}
  1085  	}
  1086  	if !empty {
  1087  		fmt.Fprintf(os.Stderr, "go: to add module requirements and sums:\n\tgo mod tidy\n")
  1088  	}
  1089  }
  1090  
  1091  // fixVersion returns a modfile.VersionFixer implemented using the Query function.
  1092  //
  1093  // It resolves commit hashes and branch names to versions,
  1094  // canonicalizes versions that appeared in early vgo drafts,
  1095  // and does nothing for versions that already appear to be canonical.
  1096  //
  1097  // The VersionFixer sets 'fixed' if it ever returns a non-canonical version.
  1098  func fixVersion(ctx context.Context, fixed *bool) modfile.VersionFixer {
  1099  	return func(path, vers string) (resolved string, err error) {
  1100  		defer func() {
  1101  			if err == nil && resolved != vers {
  1102  				*fixed = true
  1103  			}
  1104  		}()
  1105  
  1106  		// Special case: remove the old -gopkgin- hack.
  1107  		if strings.HasPrefix(path, "gopkg.in/") && strings.Contains(vers, "-gopkgin-") {
  1108  			vers = vers[strings.Index(vers, "-gopkgin-")+len("-gopkgin-"):]
  1109  		}
  1110  
  1111  		// fixVersion is called speculatively on every
  1112  		// module, version pair from every go.mod file.
  1113  		// Avoid the query if it looks OK.
  1114  		_, pathMajor, ok := module.SplitPathVersion(path)
  1115  		if !ok {
  1116  			return "", &module.ModuleError{
  1117  				Path: path,
  1118  				Err: &module.InvalidVersionError{
  1119  					Version: vers,
  1120  					Err:     fmt.Errorf("malformed module path %q", path),
  1121  				},
  1122  			}
  1123  		}
  1124  		if vers != "" && module.CanonicalVersion(vers) == vers {
  1125  			if err := module.CheckPathMajor(vers, pathMajor); err != nil {
  1126  				return "", module.VersionError(module.Version{Path: path, Version: vers}, err)
  1127  			}
  1128  			return vers, nil
  1129  		}
  1130  
  1131  		info, err := Query(ctx, path, vers, "", nil)
  1132  		if err != nil {
  1133  			return "", err
  1134  		}
  1135  		return info.Version, nil
  1136  	}
  1137  }
  1138  
  1139  // AllowMissingModuleImports allows import paths to be resolved to modules
  1140  // when there is no module root. Normally, this is forbidden because it's slow
  1141  // and there's no way to make the result reproducible, but some commands
  1142  // like 'go get' are expected to do this.
  1143  //
  1144  // This function affects the default cfg.BuildMod when outside of a module,
  1145  // so it can only be called prior to Init.
  1146  func AllowMissingModuleImports() {
  1147  	if initialized {
  1148  		panic("AllowMissingModuleImports after Init")
  1149  	}
  1150  	allowMissingModuleImports = true
  1151  }
  1152  
  1153  // makeMainModules creates a MainModuleSet and associated variables according to
  1154  // the given main modules.
  1155  func makeMainModules(ms []module.Version, rootDirs []string, modFiles []*modfile.File, indices []*modFileIndex, workFile *modfile.WorkFile) *MainModuleSet {
  1156  	for _, m := range ms {
  1157  		if m.Version != "" {
  1158  			panic("mainModulesCalled with module.Version with non empty Version field: " + fmt.Sprintf("%#v", m))
  1159  		}
  1160  	}
  1161  	modRootContainingCWD := findModuleRoot(base.Cwd())
  1162  	mainModules := &MainModuleSet{
  1163  		versions:        slices.Clip(ms),
  1164  		inGorootSrc:     map[module.Version]bool{},
  1165  		pathPrefix:      map[module.Version]string{},
  1166  		modRoot:         map[module.Version]string{},
  1167  		modFiles:        map[module.Version]*modfile.File{},
  1168  		indices:         map[module.Version]*modFileIndex{},
  1169  		highestReplaced: map[string]string{},
  1170  		workFile:        workFile,
  1171  	}
  1172  	var workFileReplaces []*modfile.Replace
  1173  	if workFile != nil {
  1174  		workFileReplaces = workFile.Replace
  1175  		mainModules.workFileReplaceMap = toReplaceMap(workFile.Replace)
  1176  	}
  1177  	mainModulePaths := make(map[string]bool)
  1178  	for _, m := range ms {
  1179  		if mainModulePaths[m.Path] {
  1180  			base.Errorf("go: module %s appears multiple times in workspace", m.Path)
  1181  		}
  1182  		mainModulePaths[m.Path] = true
  1183  	}
  1184  	replacedByWorkFile := make(map[string]bool)
  1185  	replacements := make(map[module.Version]module.Version)
  1186  	for _, r := range workFileReplaces {
  1187  		if mainModulePaths[r.Old.Path] && r.Old.Version == "" {
  1188  			base.Errorf("go: workspace module %v is replaced at all versions in the go.work file. To fix, remove the replacement from the go.work file or specify the version at which to replace the module.", r.Old.Path)
  1189  		}
  1190  		replacedByWorkFile[r.Old.Path] = true
  1191  		v, ok := mainModules.highestReplaced[r.Old.Path]
  1192  		if !ok || gover.ModCompare(r.Old.Path, r.Old.Version, v) > 0 {
  1193  			mainModules.highestReplaced[r.Old.Path] = r.Old.Version
  1194  		}
  1195  		replacements[r.Old] = r.New
  1196  	}
  1197  	for i, m := range ms {
  1198  		mainModules.pathPrefix[m] = m.Path
  1199  		mainModules.modRoot[m] = rootDirs[i]
  1200  		mainModules.modFiles[m] = modFiles[i]
  1201  		mainModules.indices[m] = indices[i]
  1202  
  1203  		if mainModules.modRoot[m] == modRootContainingCWD {
  1204  			mainModules.modContainingCWD = m
  1205  		}
  1206  
  1207  		if rel := search.InDir(rootDirs[i], cfg.GOROOTsrc); rel != "" {
  1208  			mainModules.inGorootSrc[m] = true
  1209  			if m.Path == "std" {
  1210  				// The "std" module in GOROOT/src is the Go standard library. Unlike other
  1211  				// modules, the packages in the "std" module have no import-path prefix.
  1212  				//
  1213  				// Modules named "std" outside of GOROOT/src do not receive this special
  1214  				// treatment, so it is possible to run 'go test .' in other GOROOTs to
  1215  				// test individual packages using a combination of the modified package
  1216  				// and the ordinary standard library.
  1217  				// (See https://golang.org/issue/30756.)
  1218  				mainModules.pathPrefix[m] = ""
  1219  			}
  1220  		}
  1221  
  1222  		if modFiles[i] != nil {
  1223  			curModuleReplaces := make(map[module.Version]bool)
  1224  			for _, r := range modFiles[i].Replace {
  1225  				if replacedByWorkFile[r.Old.Path] {
  1226  					continue
  1227  				}
  1228  				var newV module.Version = r.New
  1229  				if WorkFilePath() != "" && newV.Version == "" && !filepath.IsAbs(newV.Path) {
  1230  					// Since we are in a workspace, we may be loading replacements from
  1231  					// multiple go.mod files. Relative paths in those replacement are
  1232  					// relative to the go.mod file, not the workspace, so the same string
  1233  					// may refer to two different paths and different strings may refer to
  1234  					// the same path. Convert them all to be absolute instead.
  1235  					//
  1236  					// (We could do this outside of a workspace too, but it would mean that
  1237  					// replacement paths in error strings needlessly differ from what's in
  1238  					// the go.mod file.)
  1239  					newV.Path = filepath.Join(rootDirs[i], newV.Path)
  1240  				}
  1241  				if prev, ok := replacements[r.Old]; ok && !curModuleReplaces[r.Old] && prev != newV {
  1242  					base.Fatalf("go: conflicting replacements for %v:\n\t%v\n\t%v\nuse \"go work edit -replace %v=[override]\" to resolve", r.Old, prev, newV, r.Old)
  1243  				}
  1244  				curModuleReplaces[r.Old] = true
  1245  				replacements[r.Old] = newV
  1246  
  1247  				v, ok := mainModules.highestReplaced[r.Old.Path]
  1248  				if !ok || gover.ModCompare(r.Old.Path, r.Old.Version, v) > 0 {
  1249  					mainModules.highestReplaced[r.Old.Path] = r.Old.Version
  1250  				}
  1251  			}
  1252  		}
  1253  	}
  1254  	return mainModules
  1255  }
  1256  
  1257  // requirementsFromModFiles returns the set of non-excluded requirements from
  1258  // the global modFile.
  1259  func requirementsFromModFiles(ctx context.Context, workFile *modfile.WorkFile, modFiles []*modfile.File, opts *PackageOpts) *Requirements {
  1260  	var roots []module.Version
  1261  	direct := map[string]bool{}
  1262  	var pruning modPruning
  1263  	if inWorkspaceMode() {
  1264  		pruning = workspace
  1265  		roots = make([]module.Version, len(MainModules.Versions()), 2+len(MainModules.Versions()))
  1266  		copy(roots, MainModules.Versions())
  1267  		goVersion := gover.FromGoWork(workFile)
  1268  		var toolchain string
  1269  		if workFile.Toolchain != nil {
  1270  			toolchain = workFile.Toolchain.Name
  1271  		}
  1272  		roots = appendGoAndToolchainRoots(roots, goVersion, toolchain, direct)
  1273  	} else {
  1274  		pruning = pruningForGoVersion(MainModules.GoVersion())
  1275  		if len(modFiles) != 1 {
  1276  			panic(fmt.Errorf("requirementsFromModFiles called with %v modfiles outside workspace mode", len(modFiles)))
  1277  		}
  1278  		modFile := modFiles[0]
  1279  		roots, direct = rootsFromModFile(MainModules.mustGetSingleMainModule(), modFile, withToolchainRoot)
  1280  	}
  1281  
  1282  	gover.ModSort(roots)
  1283  	rs := newRequirements(pruning, roots, direct)
  1284  	return rs
  1285  }
  1286  
  1287  type addToolchainRoot bool
  1288  
  1289  const (
  1290  	omitToolchainRoot addToolchainRoot = false
  1291  	withToolchainRoot                  = true
  1292  )
  1293  
  1294  func rootsFromModFile(m module.Version, modFile *modfile.File, addToolchainRoot addToolchainRoot) (roots []module.Version, direct map[string]bool) {
  1295  	direct = make(map[string]bool)
  1296  	padding := 2 // Add padding for the toolchain and go version, added upon return.
  1297  	if !addToolchainRoot {
  1298  		padding = 1
  1299  	}
  1300  	roots = make([]module.Version, 0, padding+len(modFile.Require))
  1301  	for _, r := range modFile.Require {
  1302  		if index := MainModules.Index(m); index != nil && index.exclude[r.Mod] {
  1303  			if cfg.BuildMod == "mod" {
  1304  				fmt.Fprintf(os.Stderr, "go: dropping requirement on excluded version %s %s\n", r.Mod.Path, r.Mod.Version)
  1305  			} else {
  1306  				fmt.Fprintf(os.Stderr, "go: ignoring requirement on excluded version %s %s\n", r.Mod.Path, r.Mod.Version)
  1307  			}
  1308  			continue
  1309  		}
  1310  
  1311  		roots = append(roots, r.Mod)
  1312  		if !r.Indirect {
  1313  			direct[r.Mod.Path] = true
  1314  		}
  1315  	}
  1316  	goVersion := gover.FromGoMod(modFile)
  1317  	var toolchain string
  1318  	if addToolchainRoot && modFile.Toolchain != nil {
  1319  		toolchain = modFile.Toolchain.Name
  1320  	}
  1321  	roots = appendGoAndToolchainRoots(roots, goVersion, toolchain, direct)
  1322  	return roots, direct
  1323  }
  1324  
  1325  func appendGoAndToolchainRoots(roots []module.Version, goVersion, toolchain string, direct map[string]bool) []module.Version {
  1326  	// Add explicit go and toolchain versions, inferring as needed.
  1327  	roots = append(roots, module.Version{Path: "go", Version: goVersion})
  1328  	direct["go"] = true // Every module directly uses the language and runtime.
  1329  
  1330  	if toolchain != "" {
  1331  		roots = append(roots, module.Version{Path: "toolchain", Version: toolchain})
  1332  		// Leave the toolchain as indirect: nothing in the user's module directly
  1333  		// imports a package from the toolchain, and (like an indirect dependency in
  1334  		// a module without graph pruning) we may remove the toolchain line
  1335  		// automatically if the 'go' version is changed so that it implies the exact
  1336  		// same toolchain.
  1337  	}
  1338  	return roots
  1339  }
  1340  
  1341  // setDefaultBuildMod sets a default value for cfg.BuildMod if the -mod flag
  1342  // wasn't provided. setDefaultBuildMod may be called multiple times.
  1343  func setDefaultBuildMod() {
  1344  	if cfg.BuildModExplicit {
  1345  		if inWorkspaceMode() && cfg.BuildMod != "readonly" && cfg.BuildMod != "vendor" {
  1346  			base.Fatalf("go: -mod may only be set to readonly or vendor when in workspace mode, but it is set to %q"+
  1347  				"\n\tRemove the -mod flag to use the default readonly value, "+
  1348  				"\n\tor set GOWORK=off to disable workspace mode.", cfg.BuildMod)
  1349  		}
  1350  		// Don't override an explicit '-mod=' argument.
  1351  		return
  1352  	}
  1353  
  1354  	// TODO(#40775): commands should pass in the module mode as an option
  1355  	// to modload functions instead of relying on an implicit setting
  1356  	// based on command name.
  1357  	switch cfg.CmdName {
  1358  	case "get", "mod download", "mod init", "mod tidy", "work sync":
  1359  		// These commands are intended to update go.mod and go.sum.
  1360  		cfg.BuildMod = "mod"
  1361  		return
  1362  	case "mod graph", "mod verify", "mod why":
  1363  		// These commands should not update go.mod or go.sum, but they should be
  1364  		// able to fetch modules not in go.sum and should not report errors if
  1365  		// go.mod is inconsistent. They're useful for debugging, and they need
  1366  		// to work in buggy situations.
  1367  		cfg.BuildMod = "mod"
  1368  		return
  1369  	case "mod vendor", "work vendor":
  1370  		cfg.BuildMod = "readonly"
  1371  		return
  1372  	}
  1373  	if modRoots == nil {
  1374  		if allowMissingModuleImports {
  1375  			cfg.BuildMod = "mod"
  1376  		} else {
  1377  			cfg.BuildMod = "readonly"
  1378  		}
  1379  		return
  1380  	}
  1381  
  1382  	if len(modRoots) >= 1 {
  1383  		var goVersion string
  1384  		var versionSource string
  1385  		if inWorkspaceMode() {
  1386  			versionSource = "go.work"
  1387  			if wfg := MainModules.WorkFile().Go; wfg != nil {
  1388  				goVersion = wfg.Version
  1389  			}
  1390  		} else {
  1391  			versionSource = "go.mod"
  1392  			index := MainModules.GetSingleIndexOrNil()
  1393  			if index != nil {
  1394  				goVersion = index.goVersion
  1395  			}
  1396  		}
  1397  		vendorDir := ""
  1398  		if workFilePath != "" {
  1399  			vendorDir = filepath.Join(filepath.Dir(workFilePath), "vendor")
  1400  		} else {
  1401  			if len(modRoots) != 1 {
  1402  				panic(fmt.Errorf("outside workspace mode, but have %v modRoots", modRoots))
  1403  			}
  1404  			vendorDir = filepath.Join(modRoots[0], "vendor")
  1405  		}
  1406  		if fi, err := fsys.Stat(vendorDir); err == nil && fi.IsDir() {
  1407  			modGo := "unspecified"
  1408  			if goVersion != "" {
  1409  				if gover.Compare(goVersion, "1.14") < 0 {
  1410  					// The go version is less than 1.14. Don't set -mod=vendor by default.
  1411  					// Since a vendor directory exists, we should record why we didn't use it.
  1412  					// This message won't normally be shown, but it may appear with import errors.
  1413  					cfg.BuildModReason = fmt.Sprintf("Go version in "+versionSource+" is %s, so vendor directory was not used.", modGo)
  1414  				} else {
  1415  					vendoredWorkspace, err := modulesTextIsForWorkspace(vendorDir)
  1416  					if err != nil {
  1417  						base.Fatalf("go: reading modules.txt for vendor directory: %v", err)
  1418  					}
  1419  					if vendoredWorkspace != (versionSource == "go.work") {
  1420  						if vendoredWorkspace {
  1421  							cfg.BuildModReason = "Outside workspace mode, but vendor directory is for a workspace."
  1422  						} else {
  1423  							cfg.BuildModReason = "In workspace mode, but vendor directory is not for a workspace"
  1424  						}
  1425  					} else {
  1426  						// The Go version is at least 1.14, a vendor directory exists, and
  1427  						// the modules.txt was generated in the same mode the command is running in.
  1428  						// Set -mod=vendor by default.
  1429  						cfg.BuildMod = "vendor"
  1430  						cfg.BuildModReason = "Go version in " + versionSource + " is at least 1.14 and vendor directory exists."
  1431  						return
  1432  					}
  1433  				}
  1434  				modGo = goVersion
  1435  			}
  1436  
  1437  		}
  1438  	}
  1439  
  1440  	cfg.BuildMod = "readonly"
  1441  }
  1442  
  1443  func modulesTextIsForWorkspace(vendorDir string) (bool, error) {
  1444  	f, err := fsys.Open(filepath.Join(vendorDir, "modules.txt"))
  1445  	if errors.Is(err, os.ErrNotExist) {
  1446  		// Some vendor directories exist that don't contain modules.txt.
  1447  		// This mostly happens when converting to modules.
  1448  		// We want to preserve the behavior that mod=vendor is set (even though
  1449  		// readVendorList does nothing in that case).
  1450  		return false, nil
  1451  	}
  1452  	if err != nil {
  1453  		return false, err
  1454  	}
  1455  	var buf [512]byte
  1456  	n, err := f.Read(buf[:])
  1457  	if err != nil && err != io.EOF {
  1458  		return false, err
  1459  	}
  1460  	line, _, _ := strings.Cut(string(buf[:n]), "\n")
  1461  	if annotations, ok := strings.CutPrefix(line, "## "); ok {
  1462  		for _, entry := range strings.Split(annotations, ";") {
  1463  			entry = strings.TrimSpace(entry)
  1464  			if entry == "workspace" {
  1465  				return true, nil
  1466  			}
  1467  		}
  1468  	}
  1469  	return false, nil
  1470  }
  1471  
  1472  func mustHaveCompleteRequirements() bool {
  1473  	return cfg.BuildMod != "mod" && !inWorkspaceMode()
  1474  }
  1475  
  1476  // addGoStmt adds a go directive to the go.mod file if it does not already
  1477  // include one. The 'go' version added, if any, is the latest version supported
  1478  // by this toolchain.
  1479  func addGoStmt(modFile *modfile.File, mod module.Version, v string) {
  1480  	if modFile.Go != nil && modFile.Go.Version != "" {
  1481  		return
  1482  	}
  1483  	forceGoStmt(modFile, mod, v)
  1484  }
  1485  
  1486  func forceGoStmt(modFile *modfile.File, mod module.Version, v string) {
  1487  	if err := modFile.AddGoStmt(v); err != nil {
  1488  		base.Fatalf("go: internal error: %v", err)
  1489  	}
  1490  	rawGoVersion.Store(mod, v)
  1491  }
  1492  
  1493  var altConfigs = []string{
  1494  	".git/config",
  1495  }
  1496  
  1497  func findModuleRoot(dir string) (roots string) {
  1498  	if dir == "" {
  1499  		panic("dir not set")
  1500  	}
  1501  	dir = filepath.Clean(dir)
  1502  
  1503  	// Look for enclosing go.mod.
  1504  	for {
  1505  		if fi, err := fsys.Stat(filepath.Join(dir, "go.mod")); err == nil && !fi.IsDir() {
  1506  			return dir
  1507  		}
  1508  		d := filepath.Dir(dir)
  1509  		if d == dir {
  1510  			break
  1511  		}
  1512  		dir = d
  1513  	}
  1514  	return ""
  1515  }
  1516  
  1517  func findWorkspaceFile(dir string) (root string) {
  1518  	if dir == "" {
  1519  		panic("dir not set")
  1520  	}
  1521  	dir = filepath.Clean(dir)
  1522  
  1523  	// Look for enclosing go.mod.
  1524  	for {
  1525  		f := filepath.Join(dir, "go.work")
  1526  		if fi, err := fsys.Stat(f); err == nil && !fi.IsDir() {
  1527  			return f
  1528  		}
  1529  		d := filepath.Dir(dir)
  1530  		if d == dir {
  1531  			break
  1532  		}
  1533  		if d == cfg.GOROOT {
  1534  			// As a special case, don't cross GOROOT to find a go.work file.
  1535  			// The standard library and commands built in go always use the vendored
  1536  			// dependencies, so avoid using a most likely irrelevant go.work file.
  1537  			return ""
  1538  		}
  1539  		dir = d
  1540  	}
  1541  	return ""
  1542  }
  1543  
  1544  func findAltConfig(dir string) (root, name string) {
  1545  	if dir == "" {
  1546  		panic("dir not set")
  1547  	}
  1548  	dir = filepath.Clean(dir)
  1549  	if rel := search.InDir(dir, cfg.BuildContext.GOROOT); rel != "" {
  1550  		// Don't suggest creating a module from $GOROOT/.git/config
  1551  		// or a config file found in any parent of $GOROOT (see #34191).
  1552  		return "", ""
  1553  	}
  1554  	for {
  1555  		for _, name := range altConfigs {
  1556  			if fi, err := fsys.Stat(filepath.Join(dir, name)); err == nil && !fi.IsDir() {
  1557  				return dir, name
  1558  			}
  1559  		}
  1560  		d := filepath.Dir(dir)
  1561  		if d == dir {
  1562  			break
  1563  		}
  1564  		dir = d
  1565  	}
  1566  	return "", ""
  1567  }
  1568  
  1569  func findModulePath(dir string) (string, error) {
  1570  	// TODO(bcmills): once we have located a plausible module path, we should
  1571  	// query version control (if available) to verify that it matches the major
  1572  	// version of the most recent tag.
  1573  	// See https://golang.org/issue/29433, https://golang.org/issue/27009, and
  1574  	// https://golang.org/issue/31549.
  1575  
  1576  	// Cast about for import comments,
  1577  	// first in top-level directory, then in subdirectories.
  1578  	list, _ := os.ReadDir(dir)
  1579  	for _, info := range list {
  1580  		if info.Type().IsRegular() && strings.HasSuffix(info.Name(), ".go") {
  1581  			if com := findImportComment(filepath.Join(dir, info.Name())); com != "" {
  1582  				return com, nil
  1583  			}
  1584  		}
  1585  	}
  1586  	for _, info1 := range list {
  1587  		if info1.IsDir() {
  1588  			files, _ := os.ReadDir(filepath.Join(dir, info1.Name()))
  1589  			for _, info2 := range files {
  1590  				if info2.Type().IsRegular() && strings.HasSuffix(info2.Name(), ".go") {
  1591  					if com := findImportComment(filepath.Join(dir, info1.Name(), info2.Name())); com != "" {
  1592  						return path.Dir(com), nil
  1593  					}
  1594  				}
  1595  			}
  1596  		}
  1597  	}
  1598  
  1599  	// Look for Godeps.json declaring import path.
  1600  	data, _ := os.ReadFile(filepath.Join(dir, "Godeps/Godeps.json"))
  1601  	var cfg1 struct{ ImportPath string }
  1602  	json.Unmarshal(data, &cfg1)
  1603  	if cfg1.ImportPath != "" {
  1604  		return cfg1.ImportPath, nil
  1605  	}
  1606  
  1607  	// Look for vendor.json declaring import path.
  1608  	data, _ = os.ReadFile(filepath.Join(dir, "vendor/vendor.json"))
  1609  	var cfg2 struct{ RootPath string }
  1610  	json.Unmarshal(data, &cfg2)
  1611  	if cfg2.RootPath != "" {
  1612  		return cfg2.RootPath, nil
  1613  	}
  1614  
  1615  	// Look for path in GOPATH.
  1616  	var badPathErr error
  1617  	for _, gpdir := range filepath.SplitList(cfg.BuildContext.GOPATH) {
  1618  		if gpdir == "" {
  1619  			continue
  1620  		}
  1621  		if rel := search.InDir(dir, filepath.Join(gpdir, "src")); rel != "" && rel != "." {
  1622  			path := filepath.ToSlash(rel)
  1623  			// gorelease will alert users publishing their modules to fix their paths.
  1624  			if err := module.CheckImportPath(path); err != nil {
  1625  				badPathErr = err
  1626  				break
  1627  			}
  1628  			return path, nil
  1629  		}
  1630  	}
  1631  
  1632  	reason := "outside GOPATH, module path must be specified"
  1633  	if badPathErr != nil {
  1634  		// return a different error message if the module was in GOPATH, but
  1635  		// the module path determined above would be an invalid path.
  1636  		reason = fmt.Sprintf("bad module path inferred from directory in GOPATH: %v", badPathErr)
  1637  	}
  1638  	msg := `cannot determine module path for source directory %s (%s)
  1639  
  1640  Example usage:
  1641  	'go mod init example.com/m' to initialize a v0 or v1 module
  1642  	'go mod init example.com/m/v2' to initialize a v2 module
  1643  
  1644  Run 'go help mod init' for more information.
  1645  `
  1646  	return "", fmt.Errorf(msg, dir, reason)
  1647  }
  1648  
  1649  var (
  1650  	importCommentRE = lazyregexp.New(`(?m)^package[ \t]+[^ \t\r\n/]+[ \t]+//[ \t]+import[ \t]+(\"[^"]+\")[ \t]*\r?\n`)
  1651  )
  1652  
  1653  func findImportComment(file string) string {
  1654  	data, err := os.ReadFile(file)
  1655  	if err != nil {
  1656  		return ""
  1657  	}
  1658  	m := importCommentRE.FindSubmatch(data)
  1659  	if m == nil {
  1660  		return ""
  1661  	}
  1662  	path, err := strconv.Unquote(string(m[1]))
  1663  	if err != nil {
  1664  		return ""
  1665  	}
  1666  	return path
  1667  }
  1668  
  1669  // WriteOpts control the behavior of WriteGoMod.
  1670  type WriteOpts struct {
  1671  	DropToolchain     bool // go get toolchain@none
  1672  	ExplicitToolchain bool // go get has set explicit toolchain version
  1673  
  1674  	// TODO(bcmills): Make 'go mod tidy' update the go version in the Requirements
  1675  	// instead of writing directly to the modfile.File
  1676  	TidyWroteGo bool // Go.Version field already updated by 'go mod tidy'
  1677  }
  1678  
  1679  // WriteGoMod writes the current build list back to go.mod.
  1680  func WriteGoMod(ctx context.Context, opts WriteOpts) error {
  1681  	requirements = LoadModFile(ctx)
  1682  	return commitRequirements(ctx, opts)
  1683  }
  1684  
  1685  // commitRequirements ensures go.mod and go.sum are up to date with the current
  1686  // requirements.
  1687  //
  1688  // In "mod" mode, commitRequirements writes changes to go.mod and go.sum.
  1689  //
  1690  // In "readonly" and "vendor" modes, commitRequirements returns an error if
  1691  // go.mod or go.sum are out of date in a semantically significant way.
  1692  //
  1693  // In workspace mode, commitRequirements only writes changes to go.work.sum.
  1694  func commitRequirements(ctx context.Context, opts WriteOpts) (err error) {
  1695  	if inWorkspaceMode() {
  1696  		// go.mod files aren't updated in workspace mode, but we still want to
  1697  		// update the go.work.sum file.
  1698  		return modfetch.WriteGoSum(ctx, keepSums(ctx, loaded, requirements, addBuildListZipSums), mustHaveCompleteRequirements())
  1699  	}
  1700  	if MainModules.Len() != 1 || MainModules.ModRoot(MainModules.Versions()[0]) == "" {
  1701  		// We aren't in a module, so we don't have anywhere to write a go.mod file.
  1702  		return nil
  1703  	}
  1704  	mainModule := MainModules.mustGetSingleMainModule()
  1705  	modFile := MainModules.ModFile(mainModule)
  1706  	if modFile == nil {
  1707  		// command-line-arguments has no .mod file to write.
  1708  		return nil
  1709  	}
  1710  	modFilePath := modFilePath(MainModules.ModRoot(mainModule))
  1711  
  1712  	var list []*modfile.Require
  1713  	toolchain := ""
  1714  	goVersion := ""
  1715  	for _, m := range requirements.rootModules {
  1716  		if m.Path == "go" {
  1717  			goVersion = m.Version
  1718  			continue
  1719  		}
  1720  		if m.Path == "toolchain" {
  1721  			toolchain = m.Version
  1722  			continue
  1723  		}
  1724  		list = append(list, &modfile.Require{
  1725  			Mod:      m,
  1726  			Indirect: !requirements.direct[m.Path],
  1727  		})
  1728  	}
  1729  
  1730  	// Update go line.
  1731  	// Every MVS graph we consider should have go as a root,
  1732  	// and toolchain is either implied by the go line or explicitly a root.
  1733  	if goVersion == "" {
  1734  		base.Fatalf("go: internal error: missing go root module in WriteGoMod")
  1735  	}
  1736  	if gover.Compare(goVersion, gover.Local()) > 0 {
  1737  		// We cannot assume that we know how to update a go.mod to a newer version.
  1738  		return &gover.TooNewError{What: "updating go.mod", GoVersion: goVersion}
  1739  	}
  1740  	wroteGo := opts.TidyWroteGo
  1741  	if !wroteGo && modFile.Go == nil || modFile.Go.Version != goVersion {
  1742  		alwaysUpdate := cfg.BuildMod == "mod" || cfg.CmdName == "mod tidy" || cfg.CmdName == "get"
  1743  		if modFile.Go == nil && goVersion == gover.DefaultGoModVersion && !alwaysUpdate {
  1744  			// The go.mod has no go line, the implied default Go version matches
  1745  			// what we've computed for the graph, and we're not in one of the
  1746  			// traditional go.mod-updating programs, so leave it alone.
  1747  		} else {
  1748  			wroteGo = true
  1749  			forceGoStmt(modFile, mainModule, goVersion)
  1750  		}
  1751  	}
  1752  	if toolchain == "" {
  1753  		toolchain = "go" + goVersion
  1754  	}
  1755  
  1756  	// For reproducibility, if we are writing a new go line,
  1757  	// and we're not explicitly modifying the toolchain line with 'go get toolchain@something',
  1758  	// and the go version is one that supports switching toolchains,
  1759  	// and the toolchain running right now is newer than the current toolchain line,
  1760  	// then update the toolchain line to record the newer toolchain.
  1761  	//
  1762  	// TODO(#57001): This condition feels too complicated. Can we simplify it?
  1763  	// TODO(#57001): Add more tests for toolchain lines.
  1764  	toolVers := gover.FromToolchain(toolchain)
  1765  	if wroteGo && !opts.DropToolchain && !opts.ExplicitToolchain &&
  1766  		gover.Compare(goVersion, gover.GoStrictVersion) >= 0 &&
  1767  		(gover.Compare(gover.Local(), toolVers) > 0 && !gover.IsLang(gover.Local())) {
  1768  		toolchain = "go" + gover.Local()
  1769  		toolVers = gover.FromToolchain(toolchain)
  1770  	}
  1771  
  1772  	if opts.DropToolchain || toolchain == "go"+goVersion || (gover.Compare(toolVers, gover.GoStrictVersion) < 0 && !opts.ExplicitToolchain) {
  1773  		// go get toolchain@none or toolchain matches go line or isn't valid; drop it.
  1774  		// TODO(#57001): 'go get' should reject explicit toolchains below GoStrictVersion.
  1775  		modFile.DropToolchainStmt()
  1776  	} else {
  1777  		modFile.AddToolchainStmt(toolchain)
  1778  	}
  1779  
  1780  	// Update require blocks.
  1781  	if gover.Compare(goVersion, gover.SeparateIndirectVersion) < 0 {
  1782  		modFile.SetRequire(list)
  1783  	} else {
  1784  		modFile.SetRequireSeparateIndirect(list)
  1785  	}
  1786  	modFile.Cleanup()
  1787  
  1788  	index := MainModules.GetSingleIndexOrNil()
  1789  	dirty := index.modFileIsDirty(modFile)
  1790  	if dirty && cfg.BuildMod != "mod" {
  1791  		// If we're about to fail due to -mod=readonly,
  1792  		// prefer to report a dirty go.mod over a dirty go.sum
  1793  		return errGoModDirty
  1794  	}
  1795  
  1796  	if !dirty && cfg.CmdName != "mod tidy" {
  1797  		// The go.mod file has the same semantic content that it had before
  1798  		// (but not necessarily the same exact bytes).
  1799  		// Don't write go.mod, but write go.sum in case we added or trimmed sums.
  1800  		// 'go mod init' shouldn't write go.sum, since it will be incomplete.
  1801  		if cfg.CmdName != "mod init" {
  1802  			if err := modfetch.WriteGoSum(ctx, keepSums(ctx, loaded, requirements, addBuildListZipSums), mustHaveCompleteRequirements()); err != nil {
  1803  				return err
  1804  			}
  1805  		}
  1806  		return nil
  1807  	}
  1808  	if _, ok := fsys.OverlayPath(modFilePath); ok {
  1809  		if dirty {
  1810  			return errors.New("updates to go.mod needed, but go.mod is part of the overlay specified with -overlay")
  1811  		}
  1812  		return nil
  1813  	}
  1814  
  1815  	new, err := modFile.Format()
  1816  	if err != nil {
  1817  		return err
  1818  	}
  1819  	defer func() {
  1820  		// At this point we have determined to make the go.mod file on disk equal to new.
  1821  		MainModules.SetIndex(mainModule, indexModFile(new, modFile, mainModule, false))
  1822  
  1823  		// Update go.sum after releasing the side lock and refreshing the index.
  1824  		// 'go mod init' shouldn't write go.sum, since it will be incomplete.
  1825  		if cfg.CmdName != "mod init" {
  1826  			if err == nil {
  1827  				err = modfetch.WriteGoSum(ctx, keepSums(ctx, loaded, requirements, addBuildListZipSums), mustHaveCompleteRequirements())
  1828  			}
  1829  		}
  1830  	}()
  1831  
  1832  	// Make a best-effort attempt to acquire the side lock, only to exclude
  1833  	// previous versions of the 'go' command from making simultaneous edits.
  1834  	if unlock, err := modfetch.SideLock(ctx); err == nil {
  1835  		defer unlock()
  1836  	}
  1837  
  1838  	errNoChange := errors.New("no update needed")
  1839  
  1840  	err = lockedfile.Transform(modFilePath, func(old []byte) ([]byte, error) {
  1841  		if bytes.Equal(old, new) {
  1842  			// The go.mod file is already equal to new, possibly as the result of some
  1843  			// other process.
  1844  			return nil, errNoChange
  1845  		}
  1846  
  1847  		if index != nil && !bytes.Equal(old, index.data) {
  1848  			// The contents of the go.mod file have changed. In theory we could add all
  1849  			// of the new modules to the build list, recompute, and check whether any
  1850  			// module in *our* build list got bumped to a different version, but that's
  1851  			// a lot of work for marginal benefit. Instead, fail the command: if users
  1852  			// want to run concurrent commands, they need to start with a complete,
  1853  			// consistent module definition.
  1854  			return nil, fmt.Errorf("existing contents have changed since last read")
  1855  		}
  1856  
  1857  		return new, nil
  1858  	})
  1859  
  1860  	if err != nil && err != errNoChange {
  1861  		return fmt.Errorf("updating go.mod: %w", err)
  1862  	}
  1863  	return nil
  1864  }
  1865  
  1866  // keepSums returns the set of modules (and go.mod file entries) for which
  1867  // checksums would be needed in order to reload the same set of packages
  1868  // loaded by the most recent call to LoadPackages or ImportFromFiles,
  1869  // including any go.mod files needed to reconstruct the MVS result
  1870  // or identify go versions,
  1871  // in addition to the checksums for every module in keepMods.
  1872  func keepSums(ctx context.Context, ld *loader, rs *Requirements, which whichSums) map[module.Version]bool {
  1873  	// Every module in the full module graph contributes its requirements,
  1874  	// so in order to ensure that the build list itself is reproducible,
  1875  	// we need sums for every go.mod in the graph (regardless of whether
  1876  	// that version is selected).
  1877  	keep := make(map[module.Version]bool)
  1878  
  1879  	// Add entries for modules in the build list with paths that are prefixes of
  1880  	// paths of loaded packages. We need to retain sums for all of these modules —
  1881  	// not just the modules containing the actual packages — in order to rule out
  1882  	// ambiguous import errors the next time we load the package.
  1883  	keepModSumsForZipSums := true
  1884  	if ld == nil {
  1885  		if gover.Compare(MainModules.GoVersion(), gover.TidyGoModSumVersion) < 0 && cfg.BuildMod != "mod" {
  1886  			keepModSumsForZipSums = false
  1887  		}
  1888  	} else {
  1889  		keepPkgGoModSums := true
  1890  		if gover.Compare(ld.requirements.GoVersion(), gover.TidyGoModSumVersion) < 0 && (ld.Tidy || cfg.BuildMod != "mod") {
  1891  			keepPkgGoModSums = false
  1892  			keepModSumsForZipSums = false
  1893  		}
  1894  		for _, pkg := range ld.pkgs {
  1895  			// We check pkg.mod.Path here instead of pkg.inStd because the
  1896  			// pseudo-package "C" is not in std, but not provided by any module (and
  1897  			// shouldn't force loading the whole module graph).
  1898  			if pkg.testOf != nil || (pkg.mod.Path == "" && pkg.err == nil) || module.CheckImportPath(pkg.path) != nil {
  1899  				continue
  1900  			}
  1901  
  1902  			// We need the checksum for the go.mod file for pkg.mod
  1903  			// so that we know what Go version to use to compile pkg.
  1904  			// However, we didn't do so before Go 1.21, and the bug is relatively
  1905  			// minor, so we maintain the previous (buggy) behavior in 'go mod tidy' to
  1906  			// avoid introducing unnecessary churn.
  1907  			if keepPkgGoModSums {
  1908  				r := resolveReplacement(pkg.mod)
  1909  				keep[modkey(r)] = true
  1910  			}
  1911  
  1912  			if rs.pruning == pruned && pkg.mod.Path != "" {
  1913  				if v, ok := rs.rootSelected(pkg.mod.Path); ok && v == pkg.mod.Version {
  1914  					// pkg was loaded from a root module, and because the main module has
  1915  					// a pruned module graph we do not check non-root modules for
  1916  					// conflicts for packages that can be found in roots. So we only need
  1917  					// the checksums for the root modules that may contain pkg, not all
  1918  					// possible modules.
  1919  					for prefix := pkg.path; prefix != "."; prefix = path.Dir(prefix) {
  1920  						if v, ok := rs.rootSelected(prefix); ok && v != "none" {
  1921  							m := module.Version{Path: prefix, Version: v}
  1922  							r := resolveReplacement(m)
  1923  							keep[r] = true
  1924  						}
  1925  					}
  1926  					continue
  1927  				}
  1928  			}
  1929  
  1930  			mg, _ := rs.Graph(ctx)
  1931  			for prefix := pkg.path; prefix != "."; prefix = path.Dir(prefix) {
  1932  				if v := mg.Selected(prefix); v != "none" {
  1933  					m := module.Version{Path: prefix, Version: v}
  1934  					r := resolveReplacement(m)
  1935  					keep[r] = true
  1936  				}
  1937  			}
  1938  		}
  1939  	}
  1940  
  1941  	if rs.graph.Load() == nil {
  1942  		// We haven't needed to load the module graph so far.
  1943  		// Save sums for the root modules (or their replacements), but don't
  1944  		// incur the cost of loading the graph just to find and retain the sums.
  1945  		for _, m := range rs.rootModules {
  1946  			r := resolveReplacement(m)
  1947  			keep[modkey(r)] = true
  1948  			if which == addBuildListZipSums {
  1949  				keep[r] = true
  1950  			}
  1951  		}
  1952  	} else {
  1953  		mg, _ := rs.Graph(ctx)
  1954  		mg.WalkBreadthFirst(func(m module.Version) {
  1955  			if _, ok := mg.RequiredBy(m); ok {
  1956  				// The requirements from m's go.mod file are present in the module graph,
  1957  				// so they are relevant to the MVS result regardless of whether m was
  1958  				// actually selected.
  1959  				r := resolveReplacement(m)
  1960  				keep[modkey(r)] = true
  1961  			}
  1962  		})
  1963  
  1964  		if which == addBuildListZipSums {
  1965  			for _, m := range mg.BuildList() {
  1966  				r := resolveReplacement(m)
  1967  				if keepModSumsForZipSums {
  1968  					keep[modkey(r)] = true // we need the go version from the go.mod file to do anything useful with the zipfile
  1969  				}
  1970  				keep[r] = true
  1971  			}
  1972  		}
  1973  	}
  1974  
  1975  	return keep
  1976  }
  1977  
  1978  type whichSums int8
  1979  
  1980  const (
  1981  	loadedZipSumsOnly = whichSums(iota)
  1982  	addBuildListZipSums
  1983  )
  1984  
  1985  // modkey returns the module.Version under which the checksum for m's go.mod
  1986  // file is stored in the go.sum file.
  1987  func modkey(m module.Version) module.Version {
  1988  	return module.Version{Path: m.Path, Version: m.Version + "/go.mod"}
  1989  }
  1990  
  1991  func suggestModulePath(path string) string {
  1992  	var m string
  1993  
  1994  	i := len(path)
  1995  	for i > 0 && ('0' <= path[i-1] && path[i-1] <= '9' || path[i-1] == '.') {
  1996  		i--
  1997  	}
  1998  	url := path[:i]
  1999  	url = strings.TrimSuffix(url, "/v")
  2000  	url = strings.TrimSuffix(url, "/")
  2001  
  2002  	f := func(c rune) bool {
  2003  		return c > '9' || c < '0'
  2004  	}
  2005  	s := strings.FieldsFunc(path[i:], f)
  2006  	if len(s) > 0 {
  2007  		m = s[0]
  2008  	}
  2009  	m = strings.TrimLeft(m, "0")
  2010  	if m == "" || m == "1" {
  2011  		return url + "/v2"
  2012  	}
  2013  
  2014  	return url + "/v" + m
  2015  }
  2016  
  2017  func suggestGopkgIn(path string) string {
  2018  	var m string
  2019  	i := len(path)
  2020  	for i > 0 && (('0' <= path[i-1] && path[i-1] <= '9') || (path[i-1] == '.')) {
  2021  		i--
  2022  	}
  2023  	url := path[:i]
  2024  	url = strings.TrimSuffix(url, ".v")
  2025  	url = strings.TrimSuffix(url, "/v")
  2026  	url = strings.TrimSuffix(url, "/")
  2027  
  2028  	f := func(c rune) bool {
  2029  		return c > '9' || c < '0'
  2030  	}
  2031  	s := strings.FieldsFunc(path, f)
  2032  	if len(s) > 0 {
  2033  		m = s[0]
  2034  	}
  2035  
  2036  	m = strings.TrimLeft(m, "0")
  2037  
  2038  	if m == "" {
  2039  		return url + ".v1"
  2040  	}
  2041  	return url + ".v" + m
  2042  }
  2043  

View as plain text