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.
7 // This file contains the module-mode package loader, as well as some accessory
8 // functions pertaining to the package import graph.
10 // There are two exported entry points into package loading — LoadPackages and
11 // ImportFromFiles — both implemented in terms of loadFromRoots, which itself
12 // manipulates an instance of the loader struct.
14 // Although most of the loading state is maintained in the loader struct,
15 // one key piece - the build list - is a global, so that it can be modified
16 // separate from the loading operation, such as during "go get"
17 // upgrades/downgrades or in "go mod" operations.
18 // TODO(#40775): It might be nice to make the loader take and return
19 // a buildList rather than hard-coding use of the global.
21 // Loading is an iterative process. On each iteration, we try to load the
22 // requested packages and their transitive imports, then try to resolve modules
23 // for any imported packages that are still missing.
25 // The first step of each iteration identifies a set of “root” packages.
26 // Normally the root packages are exactly those matching the named pattern
27 // arguments. However, for the "all" meta-pattern, the final set of packages is
28 // computed from the package import graph, and therefore cannot be an initial
29 // input to loading that graph. Instead, the root packages for the "all" pattern
30 // are those contained in the main module, and allPatternIsRoot parameter to the
31 // loader instructs it to dynamically expand those roots to the full "all"
32 // pattern as loading progresses.
34 // The pkgInAll flag on each loadPkg instance tracks whether that
35 // package is known to match the "all" meta-pattern.
36 // A package matches the "all" pattern if:
37 // - it is in the main module, or
38 // - it is imported by any test in the main module, or
39 // - it is imported by another package in "all", or
40 // - the main module specifies a go version ≤ 1.15, and the package is imported
41 // by a *test of* another package in "all".
43 // When graph pruning is in effect, we want to spot-check the graph-pruning
44 // invariants — which depend on which packages are known to be in "all" — even
45 // when we are only loading individual packages, so we set the pkgInAll flag
46 // regardless of the whether the "all" pattern is a root.
47 // (This is necessary to maintain the “import invariant” described in
48 // https://golang.org/design/36460-lazy-module-loading.)
50 // Because "go mod vendor" prunes out the tests of vendored packages, the
51 // behavior of the "all" pattern with -mod=vendor in Go 1.11–1.15 is the same
52 // as the "all" pattern (regardless of the -mod flag) in 1.16+.
53 // The loader uses the GoVersion parameter to determine whether the "all"
54 // pattern should close over tests (as in Go 1.11–1.15) or stop at only those
55 // packages transitively imported by the packages and tests in the main module
56 // ("all" in Go 1.16+ and "go mod vendor" in Go 1.11+).
58 // Note that it is possible for a loaded package NOT to be in "all" even when we
59 // are loading the "all" pattern. For example, packages that are transitive
60 // dependencies of other roots named on the command line must be loaded, but are
61 // not in "all". (The mod_notall test illustrates this behavior.)
62 // Similarly, if the LoadTests flag is set but the "all" pattern does not close
63 // over test dependencies, then when we load the test of a package that is in
64 // "all" but outside the main module, the dependencies of that test will not
65 // necessarily themselves be in "all". (That configuration does not arise in Go
66 // 1.11–1.15, but it will be possible in Go 1.16+.)
68 // Loading proceeds from the roots, using a parallel work-queue with a limit on
69 // the amount of active work (to avoid saturating disks, CPU cores, and/or
70 // network connections). Each package is added to the queue the first time it is
71 // imported by another package. When we have finished identifying the imports of
72 // a package, we add the test for that package if it is needed. A test may be
74 // - the package matches a root pattern and tests of the roots were requested, or
75 // - the package is in the main module and the "all" pattern is requested
76 // (because the "all" pattern includes the dependencies of tests in the main
78 // - the package is in "all" and the definition of "all" we are using includes
79 // dependencies of tests (as is the case in Go ≤1.15).
81 // After all available packages have been loaded, we examine the results to
82 // identify any requested or imported packages that are still missing, and if
83 // so, which modules we could add to the module graph in order to make the
84 // missing packages available. We add those to the module graph and iterate,
85 // until either all packages resolve successfully or we cannot identify any
86 // module that would resolve any remaining missing package.
88 // If the main module is “tidy” (that is, if "go mod tidy" is a no-op for it)
89 // and all requested packages are in "all", then loading completes in a single
91 // TODO(bcmills): We should also be able to load in a single iteration if the
92 // requested packages all come from modules that are themselves tidy, regardless
93 // of whether those packages are in "all". Today, that requires two iterations
94 // if those packages are not found in existing dependencies of the main module.
114 "cmd/go/internal/base"
115 "cmd/go/internal/cfg"
116 "cmd/go/internal/fsys"
117 "cmd/go/internal/imports"
118 "cmd/go/internal/modfetch"
119 "cmd/go/internal/modindex"
120 "cmd/go/internal/mvs"
121 "cmd/go/internal/par"
122 "cmd/go/internal/search"
123 "cmd/go/internal/str"
125 "golang.org/x/mod/module"
126 "golang.org/x/mod/semver"
129 // loaded is the most recently-used package loader.
130 // It holds details about individual packages.
132 // This variable should only be accessed directly in top-level exported
133 // functions. All other functions that require or produce a *loader should pass
134 // or return it as an explicit parameter.
137 // PackageOpts control the behavior of the LoadPackages function.
138 type PackageOpts struct {
139 // GoVersion is the Go version to which the go.mod file should be updated
140 // after packages have been loaded.
142 // An empty GoVersion means to use the Go version already specified in the
143 // main module's go.mod file, or the latest Go version if there is no main
147 // Tags are the build tags in effect (as interpreted by the
148 // cmd/go/internal/imports package).
149 // If nil, treated as equivalent to imports.Tags().
152 // Tidy, if true, requests that the build list and go.sum file be reduced to
153 // the minimial dependencies needed to reproducibly reload the requested
157 // TidyCompatibleVersion is the oldest Go version that must be able to
158 // reproducibly reload the requested packages.
160 // If empty, the compatible version is the Go version immediately prior to the
161 // 'go' version listed in the go.mod file.
162 TidyCompatibleVersion string
164 // VendorModulesInGOROOTSrc indicates that if we are within a module in
165 // GOROOT/src, packages in the module's vendor directory should be resolved as
166 // actual module dependencies (instead of standard-library packages).
167 VendorModulesInGOROOTSrc bool
169 // ResolveMissingImports indicates that we should attempt to add module
170 // dependencies as needed to resolve imports of packages that are not found.
172 // For commands that support the -mod flag, resolving imports may still fail
173 // if the flag is set to "readonly" (the default) or "vendor".
174 ResolveMissingImports bool
176 // AssumeRootsImported indicates that the transitive dependencies of the root
177 // packages should be treated as if those roots will be imported by the main
179 AssumeRootsImported bool
181 // AllowPackage, if non-nil, is called after identifying the module providing
182 // each package. If AllowPackage returns a non-nil error, that error is set
183 // for the package, and the imports and test of that package will not be
186 // AllowPackage may be invoked concurrently by multiple goroutines,
187 // and may be invoked multiple times for a given package path.
188 AllowPackage func(ctx context.Context, path string, mod module.Version) error
190 // LoadTests loads the test dependencies of each package matching a requested
191 // pattern. If ResolveMissingImports is also true, test dependencies will be
192 // resolved if missing.
195 // UseVendorAll causes the "all" package pattern to be interpreted as if
196 // running "go mod vendor" (or building with "-mod=vendor").
198 // This is a no-op for modules that declare 'go 1.16' or higher, for which this
199 // is the default (and only) interpretation of the "all" pattern in module mode.
202 // AllowErrors indicates that LoadPackages should not terminate the process if
206 // SilencePackageErrors indicates that LoadPackages should not print errors
207 // that occur while matching or loading packages, and should not terminate the
208 // process if such an error occurs.
210 // Errors encountered in the module graph will still be reported.
212 // The caller may retrieve the silenced package errors using the Lookup
213 // function, and matching errors are still populated in the Errs field of the
214 // associated search.Match.)
215 SilencePackageErrors bool
217 // SilenceMissingStdImports indicates that LoadPackages should not print
218 // errors or terminate the process if an imported package is missing, and the
219 // import path looks like it might be in the standard library (perhaps in a
221 SilenceMissingStdImports bool
223 // SilenceNoGoErrors indicates that LoadPackages should not print
224 // imports.ErrNoGo errors.
225 // This allows the caller to invoke LoadPackages (and report other errors)
226 // without knowing whether the requested packages exist for the given tags.
228 // Note that if a requested package does not exist *at all*, it will fail
229 // during module resolution and the error will not be suppressed.
230 SilenceNoGoErrors bool
232 // SilenceUnmatchedWarnings suppresses the warnings normally emitted for
233 // patterns that did not match any packages.
234 SilenceUnmatchedWarnings bool
236 // Resolve the query against this module.
237 MainModule module.Version
240 // LoadPackages identifies the set of packages matching the given patterns and
241 // loads the packages in the import graph rooted at that set.
242 func LoadPackages(ctx context.Context, opts PackageOpts, patterns ...string) (matches []*search.Match, loadedPackages []string) {
243 if opts.Tags == nil {
244 opts.Tags = imports.Tags()
247 patterns = search.CleanPatterns(patterns)
248 matches = make([]*search.Match, 0, len(patterns))
249 allPatternIsRoot := false
250 for _, pattern := range patterns {
251 matches = append(matches, search.NewMatch(pattern))
252 if pattern == "all" {
253 allPatternIsRoot = true
257 updateMatches := func(rs *Requirements, ld *loader) {
258 for _, m := range matches {
261 // Evaluate list of file system directories on first iteration.
263 matchModRoots := modRoots
264 if opts.MainModule != (module.Version{}) {
265 matchModRoots = []string{MainModules.ModRoot(opts.MainModule)}
267 matchLocalDirs(ctx, matchModRoots, m, rs)
270 // Make a copy of the directory list and translate to import paths.
271 // Note that whether a directory corresponds to an import path
272 // changes as the build list is updated, and a directory can change
273 // from not being in the build list to being in it and back as
274 // the exact version of a particular module increases during
275 // the loader iterations.
277 for _, dir := range m.Dirs {
278 pkg, err := resolveLocalPackage(ctx, dir, rs)
280 if !m.IsLiteral() && (err == errPkgIsBuiltin || err == errPkgIsGorootSrc) {
281 continue // Don't include "builtin" or GOROOT/src in wildcard patterns.
284 // If we're outside of a module, ensure that the failure mode
295 m.Pkgs = append(m.Pkgs, pkg)
299 m.Pkgs = []string{m.Pattern()}
301 case strings.Contains(m.Pattern(), "..."):
303 mg, err := rs.Graph(ctx)
305 // The module graph is (or may be) incomplete — perhaps we failed to
306 // load the requirements of some module. This is an error in matching
307 // the patterns to packages, because we may be missing some packages
308 // or we may erroneously match packages in the wrong versions of
309 // modules. However, for cases like 'go list -e', the error should not
310 // necessarily prevent us from loading the packages we could find.
311 m.Errs = append(m.Errs, err)
313 matchPackages(ctx, m, opts.Tags, includeStd, mg.BuildList())
315 case m.Pattern() == "all":
317 // The initial roots are the packages in the main module.
318 // loadFromRoots will expand that to "all".
320 matchModules := MainModules.Versions()
321 if opts.MainModule != (module.Version{}) {
322 matchModules = []module.Version{opts.MainModule}
324 matchPackages(ctx, m, opts.Tags, omitStd, matchModules)
326 // Starting with the packages in the main module,
327 // enumerate the full list of "all".
328 m.Pkgs = ld.computePatternAll()
331 case m.Pattern() == "std" || m.Pattern() == "cmd":
333 m.MatchPackages() // Locate the packages within GOROOT/src.
337 panic(fmt.Sprintf("internal error: modload missing case for pattern %s", m.Pattern()))
342 initialRS := LoadModFile(ctx)
344 ld := loadFromRoots(ctx, loaderParams{
346 requirements: initialRS,
348 allPatternIsRoot: allPatternIsRoot,
350 listRoots: func(rs *Requirements) (roots []string) {
351 updateMatches(rs, nil)
352 for _, m := range matches {
353 roots = append(roots, m.Pkgs...)
359 // One last pass to finalize wildcards.
360 updateMatches(ld.requirements, ld)
362 // List errors in matching patterns (such as directory permission
363 // errors for wildcard patterns).
364 if !ld.SilencePackageErrors {
365 for _, match := range matches {
366 for _, err := range match.Errs {
367 ld.errorf("%v\n", err)
373 if !opts.SilenceUnmatchedWarnings {
374 search.WarnUnmatched(matches)
379 mg, _ := ld.requirements.Graph(ctx)
381 for _, m := range initialRS.rootModules {
383 if ld.requirements.pruning == unpruned {
384 // m is unused if it was dropped from the module graph entirely. If it
385 // was only demoted from direct to indirect, it may still be in use via
386 // a transitive import.
387 unused = mg.Selected(m.Path) == "none"
389 // m is unused if it was dropped from the roots. If it is still present
390 // as a transitive dependency, that transitive dependency is not needed
391 // by any package or test in the main module.
392 _, ok := ld.requirements.rootSelected(m.Path)
396 fmt.Fprintf(os.Stderr, "unused %s\n", m.Path)
401 keep := keepSums(ctx, ld, ld.requirements, loadedZipSumsOnly)
402 if compatDepth := pruningForGoVersion(ld.TidyCompatibleVersion); compatDepth != ld.requirements.pruning {
403 compatRS := newRequirements(compatDepth, ld.requirements.rootModules, ld.requirements.direct)
404 ld.checkTidyCompatibility(ctx, compatRS)
406 for m := range keepSums(ctx, ld, compatRS, loadedZipSumsOnly) {
411 if !ExplicitWriteGoMod {
412 modfetch.TrimGoSum(keep)
414 // commitRequirements below will also call WriteGoSum, but the "keep" map
415 // we have here could be strictly larger: commitRequirements only commits
416 // loaded.requirements, but here we may have also loaded (and want to
417 // preserve checksums for) additional entities from compatRS, which are
418 // only needed for compatibility with ld.TidyCompatibleVersion.
419 if err := modfetch.WriteGoSum(keep, mustHaveCompleteRequirements()); err != nil {
420 base.Fatalf("go: %v", err)
424 // Update the go.mod file's Go version if necessary.
425 if modFile := ModFile(); modFile != nil && ld.GoVersion != "" {
426 modFile.AddGoStmt(ld.GoVersion)
430 // Success! Update go.mod and go.sum (if needed) and return the results.
431 // We'll skip updating if ExplicitWriteGoMod is true (the caller has opted
432 // to call WriteGoMod itself) or if ResolveMissingImports is false (the
433 // command wants to examine the package graph as-is).
435 requirements = loaded.requirements
437 for _, pkg := range ld.pkgs {
439 loadedPackages = append(loadedPackages, pkg.path)
442 sort.Strings(loadedPackages)
444 if !ExplicitWriteGoMod && opts.ResolveMissingImports {
445 if err := commitRequirements(ctx); err != nil {
446 base.Fatalf("go: %v", err)
450 return matches, loadedPackages
453 // matchLocalDirs is like m.MatchDirs, but tries to avoid scanning directories
454 // outside of the standard library and active modules.
455 func matchLocalDirs(ctx context.Context, modRoots []string, m *search.Match, rs *Requirements) {
457 panic(fmt.Sprintf("internal error: resolveLocalDirs on non-local pattern %s", m.Pattern()))
460 if i := strings.Index(m.Pattern(), "..."); i >= 0 {
461 // The pattern is local, but it is a wildcard. Its packages will
462 // only resolve to paths if they are inside of the standard
463 // library, the main module, or some dependency of the main
464 // module. Verify that before we walk the filesystem: a filesystem
465 // walk in a directory like /var or /etc can be very expensive!
466 dir := filepath.Dir(filepath.Clean(m.Pattern()[:i+3]))
468 if !filepath.IsAbs(dir) {
469 absDir = filepath.Join(base.Cwd(), dir)
472 modRoot := findModuleRoot(absDir)
474 for _, mainModuleRoot := range modRoots {
475 if mainModuleRoot == modRoot {
480 if !found && search.InDir(absDir, cfg.GOROOTsrc) == "" && pathInModuleCache(ctx, absDir, rs) == "" {
482 scope := "main module or its selected dependencies"
483 if inWorkspaceMode() {
484 scope = "modules listed in go.work or their selected dependencies"
486 m.AddError(fmt.Errorf("directory prefix %s does not contain %s", base.ShortPath(absDir), scope))
491 m.MatchDirs(modRoots)
494 // resolveLocalPackage resolves a filesystem path to a package path.
495 func resolveLocalPackage(ctx context.Context, dir string, rs *Requirements) (string, error) {
497 if filepath.IsAbs(dir) {
498 absDir = filepath.Clean(dir)
500 absDir = filepath.Join(base.Cwd(), dir)
503 bp, err := cfg.BuildContext.ImportDir(absDir, 0)
504 if err != nil && (bp == nil || len(bp.IgnoredGoFiles) == 0) {
505 // golang.org/issue/32917: We should resolve a relative path to a
506 // package path only if the relative path actually contains the code
509 // If the named directory does not exist or contains no Go files,
510 // the package does not exist.
511 // Other errors may affect package loading, but not resolution.
512 if _, err := fsys.Stat(absDir); err != nil {
513 if os.IsNotExist(err) {
514 // Canonicalize OS-specific errors to errDirectoryNotFound so that error
515 // messages will be easier for users to search for.
516 return "", &fs.PathError{Op: "stat", Path: absDir, Err: errDirectoryNotFound}
520 if _, noGo := err.(*build.NoGoError); noGo {
521 // A directory that does not contain any Go source files — even ignored
522 // ones! — is not a Go package, and we can't resolve it to a package
523 // path because that path could plausibly be provided by some other
526 // Any other error indicates that the package “exists” (at least in the
527 // sense that it cannot exist in any other module), but has some other
528 // problem (such as a syntax error).
533 for _, mod := range MainModules.Versions() {
534 modRoot := MainModules.ModRoot(mod)
535 if modRoot != "" && absDir == modRoot {
536 if absDir == cfg.GOROOTsrc {
537 return "", errPkgIsGorootSrc
539 return MainModules.PathPrefix(mod), nil
543 // Note: The checks for @ here are just to avoid misinterpreting
544 // the module cache directories (formerly GOPATH/src/mod/foo@v1.5.2/bar).
545 // It's not strictly necessary but helpful to keep the checks.
546 var pkgNotFoundErr error
547 pkgNotFoundLongestPrefix := ""
548 for _, mainModule := range MainModules.Versions() {
549 modRoot := MainModules.ModRoot(mainModule)
550 if modRoot != "" && strings.HasPrefix(absDir, modRoot+string(filepath.Separator)) && !strings.Contains(absDir[len(modRoot):], "@") {
551 suffix := filepath.ToSlash(absDir[len(modRoot):])
552 if strings.HasPrefix(suffix, "/vendor/") {
553 if cfg.BuildMod != "vendor" {
554 return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
557 readVendorList(mainModule)
558 pkg := strings.TrimPrefix(suffix, "/vendor/")
559 if _, ok := vendorPkgModule[pkg]; !ok {
560 return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
565 mainModulePrefix := MainModules.PathPrefix(mainModule)
566 if mainModulePrefix == "" {
567 pkg := strings.TrimPrefix(suffix, "/")
568 if pkg == "builtin" {
569 // "builtin" is a pseudo-package with a real source file.
570 // It's not included in "std", so it shouldn't resolve from "."
571 // within module "std" either.
572 return "", errPkgIsBuiltin
577 pkg := mainModulePrefix + suffix
578 if _, ok, err := dirInModule(pkg, mainModulePrefix, modRoot, true); err != nil {
581 // This main module could contain the directory but doesn't. Other main
582 // modules might contain the directory, so wait till we finish the loop
583 // to see if another main module contains directory. But if not,
585 if len(mainModulePrefix) > len(pkgNotFoundLongestPrefix) {
586 pkgNotFoundLongestPrefix = mainModulePrefix
587 pkgNotFoundErr = &PackageNotInModuleError{MainModules: []module.Version{mainModule}, Pattern: pkg}
594 if pkgNotFoundErr != nil {
595 return "", pkgNotFoundErr
598 if sub := search.InDir(absDir, cfg.GOROOTsrc); sub != "" && sub != "." && !strings.Contains(sub, "@") {
599 pkg := filepath.ToSlash(sub)
600 if pkg == "builtin" {
601 return "", errPkgIsBuiltin
606 pkg := pathInModuleCache(ctx, absDir, rs)
608 if inWorkspaceMode() {
609 if mr := findModuleRoot(absDir); mr != "" {
610 return "", fmt.Errorf("directory %s is contained in a module that is not one of the workspace modules listed in go.work. You can add the module to the workspace using go work use %s", base.ShortPath(absDir), base.ShortPath(mr))
612 return "", fmt.Errorf("directory %s outside modules listed in go.work or their selected dependencies", base.ShortPath(absDir))
614 return "", fmt.Errorf("directory %s outside main module or its selected dependencies", base.ShortPath(absDir))
620 errDirectoryNotFound = errors.New("directory not found")
621 errPkgIsGorootSrc = errors.New("GOROOT/src is not an importable package")
622 errPkgIsBuiltin = errors.New(`"builtin" is a pseudo-package, not an importable package`)
625 // pathInModuleCache returns the import path of the directory dir,
626 // if dir is in the module cache copy of a module in our build list.
627 func pathInModuleCache(ctx context.Context, dir string, rs *Requirements) string {
628 tryMod := func(m module.Version) (string, bool) {
631 if repl := Replacement(m); repl.Path != "" && repl.Version == "" {
633 if !filepath.IsAbs(root) {
634 root = filepath.Join(replaceRelativeTo(), root)
636 } else if repl.Path != "" {
637 root, err = modfetch.DownloadDir(repl)
639 root, err = modfetch.DownloadDir(m)
645 sub := search.InDir(dir, root)
649 sub = filepath.ToSlash(sub)
650 if strings.Contains(sub, "/vendor/") || strings.HasPrefix(sub, "vendor/") || strings.Contains(sub, "@") {
654 return path.Join(m.Path, filepath.ToSlash(sub)), true
657 if rs.pruning == pruned {
658 for _, m := range rs.rootModules {
659 if v, _ := rs.rootSelected(m.Path); v != m.Version {
660 continue // m is a root, but we have a higher root for the same path.
662 if importPath, ok := tryMod(m); ok {
663 // checkMultiplePaths ensures that a module can be used for at most one
664 // requirement, so this must be it.
670 // None of the roots contained dir, or the graph is unpruned (so we don't want
671 // to distinguish between roots and transitive dependencies). Either way,
672 // check the full graph to see if the directory is a non-root dependency.
674 // If the roots are not consistent with the full module graph, the selected
675 // versions of root modules may differ from what we already checked above.
676 // Re-check those paths too.
678 mg, _ := rs.Graph(ctx)
679 var importPath string
680 for _, m := range mg.BuildList() {
682 importPath, found = tryMod(m)
690 // ImportFromFiles adds modules to the build list as needed
691 // to satisfy the imports in the named Go source files.
693 // Errors in missing dependencies are silenced.
695 // TODO(bcmills): Silencing errors seems off. Take a closer look at this and
696 // figure out what the error-reporting actually ought to be.
697 func ImportFromFiles(ctx context.Context, gofiles []string) {
698 rs := LoadModFile(ctx)
700 tags := imports.Tags()
701 imports, testImports, err := imports.ScanFiles(gofiles, tags)
703 base.Fatalf("go: %v", err)
706 loaded = loadFromRoots(ctx, loaderParams{
707 PackageOpts: PackageOpts{
709 ResolveMissingImports: true,
710 SilencePackageErrors: true,
713 listRoots: func(*Requirements) (roots []string) {
714 roots = append(roots, imports...)
715 roots = append(roots, testImports...)
719 requirements = loaded.requirements
721 if !ExplicitWriteGoMod {
722 if err := commitRequirements(ctx); err != nil {
723 base.Fatalf("go: %v", err)
728 // DirImportPath returns the effective import path for dir,
729 // provided it is within a main module, or else returns ".".
730 func (mms *MainModuleSet) DirImportPath(ctx context.Context, dir string) (path string, m module.Version) {
732 return ".", module.Version{}
734 LoadModFile(ctx) // Sets targetPrefix.
736 if !filepath.IsAbs(dir) {
737 dir = filepath.Join(base.Cwd(), dir)
739 dir = filepath.Clean(dir)
742 var longestPrefix string
743 var longestPrefixPath string
744 var longestPrefixVersion module.Version
745 for _, v := range mms.Versions() {
746 modRoot := mms.ModRoot(v)
748 return mms.PathPrefix(v), v
750 if strings.HasPrefix(dir, modRoot+string(filepath.Separator)) {
751 pathPrefix := MainModules.PathPrefix(v)
752 if pathPrefix > longestPrefix {
753 longestPrefix = pathPrefix
754 longestPrefixVersion = v
755 suffix := filepath.ToSlash(dir[len(modRoot):])
756 if strings.HasPrefix(suffix, "/vendor/") {
757 longestPrefixPath = strings.TrimPrefix(suffix, "/vendor/")
759 longestPrefixPath = mms.PathPrefix(v) + suffix
763 if len(longestPrefix) > 0 {
764 return longestPrefixPath, longestPrefixVersion
767 return ".", module.Version{}
770 // ImportMap returns the actual package import path
771 // for an import path found in source code.
772 // If the given import path does not appear in the source code
773 // for the packages that have been loaded, ImportMap returns the empty string.
774 func ImportMap(path string) string {
775 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
782 // PackageDir returns the directory containing the source code
783 // for the package named by the import path.
784 func PackageDir(path string) string {
785 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
792 // PackageModule returns the module providing the package named by the import path.
793 func PackageModule(path string) module.Version {
794 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
796 return module.Version{}
801 // Lookup returns the source directory, import path, and any loading error for
802 // the package at path as imported from the package in parentDir.
803 // Lookup requires that one of the Load functions in this package has already
805 func Lookup(parentPath string, parentIsStd bool, path string) (dir, realPath string, err error) {
807 panic("Lookup called with empty package path")
811 path = loaded.stdVendor(parentPath, path)
813 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
815 // The loader should have found all the relevant paths.
816 // There are a few exceptions, though:
817 // - during go list without -test, the p.Resolve calls to process p.TestImports and p.XTestImports
818 // end up here to canonicalize the import paths.
819 // - during any load, non-loaded packages like "unsafe" end up here.
820 // - during any load, build-injected dependencies like "runtime/cgo" end up here.
821 // - because we ignore appengine/* in the module loader,
822 // the dependencies of any actual appengine/* library end up here.
823 dir := findStandardImportPath(path)
825 return dir, path, nil
827 return "", "", errMissing
829 return pkg.dir, pkg.path, pkg.err
832 // A loader manages the process of loading information about
833 // the required packages for a particular build,
834 // checking that the packages are available in the module set,
835 // and updating the module set if needed.
839 // allClosesOverTests indicates whether the "all" pattern includes
840 // dependencies of tests outside the main module (as in Go 1.11–1.15).
841 // (Otherwise — as in Go 1.16+ — the "all" pattern includes only the packages
842 // transitively *imported by* the packages and tests in the main module.)
843 allClosesOverTests bool
847 // reset on each iteration
849 pkgCache *par.Cache // package path (string) → *loadPkg
850 pkgs []*loadPkg // transitive closure of loaded packages and tests; populated in buildStacks
853 // loaderParams configure the packages loaded by, and the properties reported
854 // by, a loader instance.
855 type loaderParams struct {
857 requirements *Requirements
859 allPatternIsRoot bool // Is the "all" pattern an additional root?
861 listRoots func(rs *Requirements) []string
864 func (ld *loader) reset() {
866 case <-ld.work.Idle():
868 panic("loader.reset when not idle")
872 ld.pkgCache = new(par.Cache)
876 // errorf reports an error via either os.Stderr or base.Errorf,
877 // according to whether ld.AllowErrors is set.
878 func (ld *loader) errorf(format string, args ...any) {
880 fmt.Fprintf(os.Stderr, format, args...)
882 base.Errorf(format, args...)
886 // A loadPkg records information about a single loaded package.
887 type loadPkg struct {
888 // Populated at construction time:
889 path string // import path
892 // Populated at construction time and updated by (*loader).applyPkgFlags:
893 flags atomicLoadPkgFlags
895 // Populated by (*loader).load:
896 mod module.Version // module providing package
897 dir string // directory containing source code
898 err error // error loading package
899 imports []*loadPkg // packages imported by this one
900 testImports []string // test-only imports, saved for use by pkg.test.
902 altMods []module.Version // modules that could have contained the package but did not
904 // Populated by (*loader).pkgTest:
908 // Populated by postprocessing in (*loader).buildStacks:
909 stack *loadPkg // package importing this one in minimal import stack for this pkg
912 // loadPkgFlags is a set of flags tracking metadata about a package.
913 type loadPkgFlags int8
916 // pkgInAll indicates that the package is in the "all" package pattern,
917 // regardless of whether we are loading the "all" package pattern.
919 // When the pkgInAll flag and pkgImportsLoaded flags are both set, the caller
920 // who set the last of those flags must propagate the pkgInAll marking to all
921 // of the imports of the marked package.
923 // A test is marked with pkgInAll if that test would promote the packages it
924 // imports to be in "all" (such as when the test is itself within the main
925 // module, or when ld.allClosesOverTests is true).
926 pkgInAll loadPkgFlags = 1 << iota
928 // pkgIsRoot indicates that the package matches one of the root package
929 // patterns requested by the caller.
931 // If LoadTests is set, then when pkgIsRoot and pkgImportsLoaded are both set,
932 // the caller who set the last of those flags must populate a test for the
933 // package (in the pkg.test field).
935 // If the "all" pattern is included as a root, then non-test packages in "all"
936 // are also roots (and must be marked pkgIsRoot).
939 // pkgFromRoot indicates that the package is in the transitive closure of
940 // imports starting at the roots. (Note that every package marked as pkgIsRoot
941 // is also trivially marked pkgFromRoot.)
944 // pkgImportsLoaded indicates that the imports and testImports fields of a
945 // loadPkg have been populated.
949 // has reports whether all of the flags in cond are set in f.
950 func (f loadPkgFlags) has(cond loadPkgFlags) bool {
951 return f&cond == cond
954 // An atomicLoadPkgFlags stores a loadPkgFlags for which individual flags can be
956 type atomicLoadPkgFlags struct {
960 // update sets the given flags in af (in addition to any flags already set).
962 // update returns the previous flag state so that the caller may determine which
963 // flags were newly-set.
964 func (af *atomicLoadPkgFlags) update(flags loadPkgFlags) (old loadPkgFlags) {
966 old := atomic.LoadInt32(&af.bits)
967 new := old | int32(flags)
968 if new == old || atomic.CompareAndSwapInt32(&af.bits, old, new) {
969 return loadPkgFlags(old)
974 // has reports whether all of the flags in cond are set in af.
975 func (af *atomicLoadPkgFlags) has(cond loadPkgFlags) bool {
976 return loadPkgFlags(atomic.LoadInt32(&af.bits))&cond == cond
979 // isTest reports whether pkg is a test of another package.
980 func (pkg *loadPkg) isTest() bool {
981 return pkg.testOf != nil
984 // fromExternalModule reports whether pkg was loaded from a module other than
986 func (pkg *loadPkg) fromExternalModule() bool {
987 if pkg.mod.Path == "" {
988 return false // loaded from the standard library, not a module
990 return !MainModules.Contains(pkg.mod.Path)
993 var errMissing = errors.New("cannot find package")
995 // loadFromRoots attempts to load the build graph needed to process a set of
996 // root packages and their dependencies.
998 // The set of root packages is returned by the params.listRoots function, and
999 // expanded to the full set of packages by tracing imports (and possibly tests)
1001 func loadFromRoots(ctx context.Context, params loaderParams) *loader {
1003 loaderParams: params,
1004 work: par.NewQueue(runtime.GOMAXPROCS(0)),
1007 if ld.GoVersion == "" {
1008 ld.GoVersion = MainModules.GoVersion()
1010 if ld.Tidy && semver.Compare("v"+ld.GoVersion, "v"+LatestGoVersion()) > 0 {
1011 ld.errorf("go: go.mod file indicates go %s, but maximum version supported by tidy is %s\n", ld.GoVersion, LatestGoVersion())
1017 if ld.TidyCompatibleVersion == "" {
1018 ld.TidyCompatibleVersion = priorGoVersion(ld.GoVersion)
1019 } else if semver.Compare("v"+ld.TidyCompatibleVersion, "v"+ld.GoVersion) > 0 {
1020 // Each version of the Go toolchain knows how to interpret go.mod and
1021 // go.sum files produced by all previous versions, so a compatibility
1022 // version higher than the go.mod version adds nothing.
1023 ld.TidyCompatibleVersion = ld.GoVersion
1027 if semver.Compare("v"+ld.GoVersion, narrowAllVersionV) < 0 && !ld.UseVendorAll {
1028 // The module's go version explicitly predates the change in "all" for graph
1029 // pruning, so continue to use the older interpretation.
1030 ld.allClosesOverTests = true
1034 desiredPruning := pruningForGoVersion(ld.GoVersion)
1035 if ld.requirements.pruning == workspace {
1036 desiredPruning = workspace
1038 ld.requirements, err = convertPruning(ctx, ld.requirements, desiredPruning)
1040 ld.errorf("go: %v\n", err)
1043 if ld.requirements.pruning == unpruned {
1044 // If the module graph does not support pruning, we assume that we will need
1045 // the full module graph in order to load package dependencies.
1047 // This might not be strictly necessary, but it matches the historical
1048 // behavior of the 'go' command and keeps the go.mod file more consistent in
1049 // case of erroneous hand-edits — which are less likely to be detected by
1050 // spot-checks in modules that do not maintain the expanded go.mod
1051 // requirements needed for graph pruning.
1053 ld.requirements, _, err = expandGraph(ctx, ld.requirements)
1055 ld.errorf("go: %v\n", err)
1062 // Load the root packages and their imports.
1063 // Note: the returned roots can change on each iteration,
1064 // since the expansion of package patterns depends on the
1065 // build list we're using.
1066 rootPkgs := ld.listRoots(ld.requirements)
1068 if ld.requirements.pruning == pruned && cfg.BuildMod == "mod" {
1069 // Before we start loading transitive imports of packages, locate all of
1070 // the root packages and promote their containing modules to root modules
1071 // dependencies. If their go.mod files are tidy (the common case) and the
1072 // set of root packages does not change then we can select the correct
1073 // versions of all transitive imports on the first try and complete
1074 // loading in a single iteration.
1075 changedBuildList := ld.preloadRootModules(ctx, rootPkgs)
1076 if changedBuildList {
1077 // The build list has changed, so the set of root packages may have also
1078 // changed. Start over to pick up the changes. (Preloading roots is much
1079 // cheaper than loading the full import graph, so we would rather pay
1080 // for an extra iteration of preloading than potentially end up
1081 // discarding the result of a full iteration of loading.)
1086 inRoots := map[*loadPkg]bool{}
1087 for _, path := range rootPkgs {
1088 root := ld.pkg(ctx, path, pkgIsRoot)
1090 ld.roots = append(ld.roots, root)
1091 inRoots[root] = true
1095 // ld.pkg adds imported packages to the work queue and calls applyPkgFlags,
1096 // which adds tests (and test dependencies) as needed.
1098 // When all of the work in the queue has completed, we'll know that the
1099 // transitive closure of dependencies has been loaded.
1104 changed, err := ld.updateRequirements(ctx)
1106 ld.errorf("go: %v\n", err)
1110 // Don't resolve missing imports until the module graph has stabilized.
1111 // If the roots are still changing, they may turn out to specify a
1112 // requirement on the missing package(s), and we would rather use a
1113 // version specified by a new root than add a new dependency on an
1114 // unrelated version.
1118 if !ld.ResolveMissingImports || (!HasModRoot() && !allowMissingModuleImports) {
1119 // We've loaded as much as we can without resolving missing imports.
1123 modAddedBy := ld.resolveMissingImports(ctx)
1124 if len(modAddedBy) == 0 {
1125 // The roots are stable, and we've resolved all of the missing packages
1130 toAdd := make([]module.Version, 0, len(modAddedBy))
1131 for m, _ := range modAddedBy {
1132 toAdd = append(toAdd, m)
1134 module.Sort(toAdd) // to make errors deterministic
1136 // We ran updateRequirements before resolving missing imports and it didn't
1137 // make any changes, so we know that the requirement graph is already
1138 // consistent with ld.pkgs: we don't need to pass ld.pkgs to updateRoots
1139 // again. (That would waste time looking for changes that we have already
1141 var noPkgs []*loadPkg
1142 // We also know that we're going to call updateRequirements again next
1143 // iteration so we don't need to also update it here. (That would waste time
1144 // computing a "direct" map that we'll have to recompute later anyway.)
1145 direct := ld.requirements.direct
1146 rs, err := updateRoots(ctx, direct, ld.requirements, noPkgs, toAdd, ld.AssumeRootsImported)
1148 // If an error was found in a newly added module, report the package
1149 // import stack instead of the module requirement stack. Packages
1150 // are more descriptive.
1151 if err, ok := err.(*mvs.BuildListError); ok {
1152 if pkg := modAddedBy[err.Module()]; pkg != nil {
1153 ld.errorf("go: %s: %v\n", pkg.stackText(), err.Err)
1157 ld.errorf("go: %v\n", err)
1160 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1161 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1162 // set of modules to add to the graph, but adding those modules had no
1163 // effect — either they were already in the graph, or updateRoots did not
1164 // add them as requested.
1165 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1167 ld.requirements = rs
1169 base.ExitIfErrors() // TODO(bcmills): Is this actually needed?
1171 // Tidy the build list, if applicable, before we report errors.
1172 // (The process of tidying may remove errors from irrelevant dependencies.)
1174 rs, err := tidyRoots(ctx, ld.requirements, ld.pkgs)
1176 ld.errorf("go: %v\n", err)
1179 if ld.requirements.pruning == pruned {
1180 // We continuously add tidy roots to ld.requirements during loading, so at
1181 // this point the tidy roots should be a subset of the roots of
1182 // ld.requirements, ensuring that no new dependencies are brought inside
1183 // the graph-pruning horizon.
1184 // If that is not the case, there is a bug in the loading loop above.
1185 for _, m := range rs.rootModules {
1186 if v, ok := ld.requirements.rootSelected(m.Path); !ok || v != m.Version {
1187 ld.errorf("go: internal error: a requirement on %v is needed but was not added during package loading\n", m)
1192 ld.requirements = rs
1195 // Report errors, if any.
1196 for _, pkg := range ld.pkgs {
1201 // Add importer information to checksum errors.
1202 if sumErr := (*ImportMissingSumError)(nil); errors.As(pkg.err, &sumErr) {
1203 if importer := pkg.stack; importer != nil {
1204 sumErr.importer = importer.path
1205 sumErr.importerVersion = importer.mod.Version
1206 sumErr.importerIsTest = importer.testOf != nil
1210 if ld.SilencePackageErrors {
1213 if stdErr := (*ImportMissingError)(nil); errors.As(pkg.err, &stdErr) &&
1214 stdErr.isStd && ld.SilenceMissingStdImports {
1217 if ld.SilenceNoGoErrors && errors.Is(pkg.err, imports.ErrNoGo) {
1221 ld.errorf("%s: %v\n", pkg.stackText(), pkg.err)
1224 ld.checkMultiplePaths()
1228 // updateRequirements ensures that ld.requirements is consistent with the
1229 // information gained from ld.pkgs.
1233 // - Modules that provide packages directly imported from the main module are
1234 // marked as direct, and are promoted to explicit roots. If a needed root
1235 // cannot be promoted due to -mod=readonly or -mod=vendor, the importing
1236 // package is marked with an error.
1238 // - If ld scanned the "all" pattern independent of build constraints, it is
1239 // guaranteed to have seen every direct import. Module dependencies that did
1240 // not provide any directly-imported package are then marked as indirect.
1242 // - Root dependencies are updated to their selected versions.
1244 // The "changed" return value reports whether the update changed the selected
1245 // version of any module that either provided a loaded package or may now
1246 // provide a package that was previously unresolved.
1247 func (ld *loader) updateRequirements(ctx context.Context) (changed bool, err error) {
1248 rs := ld.requirements
1250 // direct contains the set of modules believed to provide packages directly
1251 // imported by the main module.
1252 var direct map[string]bool
1254 // If we didn't scan all of the imports from the main module, or didn't use
1255 // imports.AnyTags, then we didn't necessarily load every package that
1256 // contributes “direct” imports — so we can't safely mark existing direct
1257 // dependencies in ld.requirements as indirect-only. Propagate them as direct.
1258 loadedDirect := ld.allPatternIsRoot && reflect.DeepEqual(ld.Tags, imports.AnyTags())
1260 direct = make(map[string]bool)
1262 // TODO(bcmills): It seems like a shame to allocate and copy a map here when
1263 // it will only rarely actually vary from rs.direct. Measure this cost and
1264 // maybe avoid the copy.
1265 direct = make(map[string]bool, len(rs.direct))
1266 for mPath := range rs.direct {
1267 direct[mPath] = true
1271 for _, pkg := range ld.pkgs {
1272 if pkg.mod.Version != "" || !MainModules.Contains(pkg.mod.Path) {
1275 for _, dep := range pkg.imports {
1276 if !dep.fromExternalModule() {
1280 if inWorkspaceMode() {
1281 // In workspace mode / workspace pruning mode, the roots are the main modules
1282 // rather than the main module's direct dependencies. The check below on the selected
1283 // roots does not apply.
1284 if mg, err := rs.Graph(ctx); err != nil {
1286 } else if _, ok := mg.RequiredBy(dep.mod); !ok {
1287 // dep.mod is not an explicit dependency, but needs to be.
1288 // See comment on error returned below.
1289 pkg.err = &DirectImportFromImplicitDependencyError{
1290 ImporterPath: pkg.path,
1291 ImportedPath: dep.path,
1298 if pkg.err == nil && cfg.BuildMod != "mod" {
1299 if v, ok := rs.rootSelected(dep.mod.Path); !ok || v != dep.mod.Version {
1300 // dep.mod is not an explicit dependency, but needs to be.
1301 // Because we are not in "mod" mode, we will not be able to update it.
1302 // Instead, mark the importing package with an error.
1304 // TODO(#41688): The resulting error message fails to include the file
1305 // position of the import statement (because that information is not
1306 // tracked by the module loader). Figure out how to plumb the import
1307 // position through.
1308 pkg.err = &DirectImportFromImplicitDependencyError{
1309 ImporterPath: pkg.path,
1310 ImportedPath: dep.path,
1313 // cfg.BuildMod does not allow us to change dep.mod to be a direct
1314 // dependency, so don't mark it as such.
1319 // dep is a package directly imported by a package or test in the main
1320 // module and loaded from some other module (not the standard library).
1321 // Mark its module as a direct dependency.
1322 direct[dep.mod.Path] = true
1326 var addRoots []module.Version
1328 // When we are tidying a module with a pruned dependency graph, we may need
1329 // to add roots to preserve the versions of indirect, test-only dependencies
1330 // that are upgraded above or otherwise missing from the go.mod files of
1331 // direct dependencies. (For example, the direct dependency might be a very
1332 // stable codebase that predates modules and thus lacks a go.mod file, or
1333 // the author of the direct dependency may have forgotten to commit a change
1334 // to the go.mod file, or may have made an erroneous hand-edit that causes
1335 // it to be untidy.)
1337 // Promoting an indirect dependency to a root adds the next layer of its
1338 // dependencies to the module graph, which may increase the selected
1339 // versions of other modules from which we have already loaded packages.
1340 // So after we promote an indirect dependency to a root, we need to reload
1341 // packages, which means another iteration of loading.
1343 // As an extra wrinkle, the upgrades due to promoting a root can cause
1344 // previously-resolved packages to become unresolved. For example, the
1345 // module providing an unstable package might be upgraded to a version
1346 // that no longer contains that package. If we then resolve the missing
1347 // package, we might add yet another root that upgrades away some other
1348 // dependency. (The tests in mod_tidy_convergence*.txt illustrate some
1349 // particularly worrisome cases.)
1351 // To ensure that this process of promoting, adding, and upgrading roots
1352 // eventually terminates, during iteration we only ever add modules to the
1353 // root set — we only remove irrelevant roots at the very end of
1354 // iteration, after we have already added every root that we plan to need
1355 // in the (eventual) tidy root set.
1357 // Since we do not remove any roots during iteration, even if they no
1358 // longer provide any imported packages, the selected versions of the
1359 // roots can only increase and the set of roots can only expand. The set
1360 // of extant root paths is finite and the set of versions of each path is
1361 // finite, so the iteration *must* reach a stable fixed-point.
1362 tidy, err := tidyRoots(ctx, rs, ld.pkgs)
1366 addRoots = tidy.rootModules
1369 rs, err = updateRoots(ctx, direct, rs, ld.pkgs, addRoots, ld.AssumeRootsImported)
1371 // We don't actually know what even the root requirements are supposed to be,
1372 // so we can't proceed with loading. Return the error to the caller
1376 if rs != ld.requirements && !reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1377 // The roots of the module graph have changed in some way (not just the
1378 // "direct" markings). Check whether the changes affected any of the loaded
1380 mg, err := rs.Graph(ctx)
1384 for _, pkg := range ld.pkgs {
1385 if pkg.fromExternalModule() && mg.Selected(pkg.mod.Path) != pkg.mod.Version {
1390 // Promoting a module to a root may resolve an import that was
1391 // previously missing (by pulling in a previously-prune dependency that
1392 // provides it) or ambiguous (by promoting exactly one of the
1393 // alternatives to a root and ignoring the second-level alternatives) or
1394 // otherwise errored out (by upgrading from a version that cannot be
1395 // fetched to one that can be).
1397 // Instead of enumerating all of the possible errors, we'll just check
1398 // whether importFromModules returns nil for the package.
1399 // False-positives are ok: if we have a false-positive here, we'll do an
1400 // extra iteration of package loading this time, but we'll still
1401 // converge when the root set stops changing.
1403 // In some sense, we can think of this as ‘upgraded the module providing
1404 // pkg.path from "none" to a version higher than "none"’.
1405 if _, _, _, _, err = importFromModules(ctx, pkg.path, rs, nil); err == nil {
1413 ld.requirements = rs
1417 // resolveMissingImports returns a set of modules that could be added as
1418 // dependencies in order to resolve missing packages from pkgs.
1420 // The newly-resolved packages are added to the addedModuleFor map, and
1421 // resolveMissingImports returns a map from each new module version to
1422 // the first missing package that module would resolve.
1423 func (ld *loader) resolveMissingImports(ctx context.Context) (modAddedBy map[module.Version]*loadPkg) {
1424 type pkgMod struct {
1428 var pkgMods []pkgMod
1429 for _, pkg := range ld.pkgs {
1434 // If we are missing a test, we are also missing its non-test version, and
1435 // we should only add the missing import once.
1438 if !errors.As(pkg.err, new(*ImportMissingError)) {
1439 // Leave other errors for Import or load.Packages to report.
1444 var mod module.Version
1445 ld.work.Add(func() {
1447 mod, err = queryImport(ctx, pkg.path, ld.requirements)
1449 var ime *ImportMissingError
1450 if errors.As(err, &ime) {
1451 for curstack := pkg.stack; curstack != nil; curstack = curstack.stack {
1452 if MainModules.Contains(curstack.mod.Path) {
1453 ime.ImportingMainModule = curstack.mod
1458 // pkg.err was already non-nil, so we can reasonably attribute the error
1459 // for pkg to either the original error or the one returned by
1460 // queryImport. The existing error indicates only that we couldn't find
1461 // the package, whereas the query error also explains why we didn't fix
1462 // the problem — so we prefer the latter.
1466 // err is nil, but we intentionally leave pkg.err non-nil and pkg.mod
1467 // unset: we still haven't satisfied other invariants of a
1468 // successfully-loaded package, such as scanning and loading the imports
1469 // of that package. If we succeed in resolving the new dependency graph,
1470 // the caller can reload pkg and update the error at that point.
1472 // Even then, the package might not be loaded from the version we've
1473 // identified here. The module may be upgraded by some other dependency,
1474 // or by a transitive dependency of mod itself, or — less likely — the
1475 // package may be rejected by an AllowPackage hook or rendered ambiguous
1476 // by some other newly-added or newly-upgraded dependency.
1479 pkgMods = append(pkgMods, pkgMod{pkg: pkg, mod: &mod})
1483 modAddedBy = map[module.Version]*loadPkg{}
1484 for _, pm := range pkgMods {
1485 pkg, mod := pm.pkg, *pm.mod
1490 fmt.Fprintf(os.Stderr, "go: found %s in %s %s\n", pkg.path, mod.Path, mod.Version)
1491 if modAddedBy[mod] == nil {
1492 modAddedBy[mod] = pkg
1499 // pkg locates the *loadPkg for path, creating and queuing it for loading if
1500 // needed, and updates its state to reflect the given flags.
1502 // The imports of the returned *loadPkg will be loaded asynchronously in the
1503 // ld.work queue, and its test (if requested) will also be populated once
1504 // imports have been resolved. When ld.work goes idle, all transitive imports of
1505 // the requested package (and its test, if requested) will have been loaded.
1506 func (ld *loader) pkg(ctx context.Context, path string, flags loadPkgFlags) *loadPkg {
1507 if flags.has(pkgImportsLoaded) {
1508 panic("internal error: (*loader).pkg called with pkgImportsLoaded flag set")
1511 pkg := ld.pkgCache.Do(path, func() any {
1515 ld.applyPkgFlags(ctx, pkg, flags)
1517 ld.work.Add(func() { ld.load(ctx, pkg) })
1521 ld.applyPkgFlags(ctx, pkg, flags)
1525 // applyPkgFlags updates pkg.flags to set the given flags and propagate the
1526 // (transitive) effects of those flags, possibly loading or enqueueing further
1527 // packages as a result.
1528 func (ld *loader) applyPkgFlags(ctx context.Context, pkg *loadPkg, flags loadPkgFlags) {
1533 if flags.has(pkgInAll) && ld.allPatternIsRoot && !pkg.isTest() {
1534 // This package matches a root pattern by virtue of being in "all".
1537 if flags.has(pkgIsRoot) {
1538 flags |= pkgFromRoot
1541 old := pkg.flags.update(flags)
1543 if new == old || !new.has(pkgImportsLoaded) {
1544 // We either didn't change the state of pkg, or we don't know anything about
1545 // its dependencies yet. Either way, we can't usefully load its test or
1546 // update its dependencies.
1551 // Check whether we should add (or update the flags for) a test for pkg.
1552 // ld.pkgTest is idempotent and extra invocations are inexpensive,
1553 // so it's ok if we call it more than is strictly necessary.
1556 case ld.allPatternIsRoot && MainModules.Contains(pkg.mod.Path):
1557 // We are loading the "all" pattern, which includes packages imported by
1558 // tests in the main module. This package is in the main module, so we
1559 // need to identify the imports of its test even if LoadTests is not set.
1561 // (We will filter out the extra tests explicitly in computePatternAll.)
1564 case ld.allPatternIsRoot && ld.allClosesOverTests && new.has(pkgInAll):
1565 // This variant of the "all" pattern includes imports of tests of every
1566 // package that is itself in "all", and pkg is in "all", so its test is
1567 // also in "all" (as above).
1570 case ld.LoadTests && new.has(pkgIsRoot):
1571 // LoadTest explicitly requests tests of “the root packages”.
1576 var testFlags loadPkgFlags
1577 if MainModules.Contains(pkg.mod.Path) || (ld.allClosesOverTests && new.has(pkgInAll)) {
1578 // Tests of packages in the main module are in "all", in the sense that
1579 // they cause the packages they import to also be in "all". So are tests
1580 // of packages in "all" if "all" closes over test dependencies.
1581 testFlags |= pkgInAll
1583 ld.pkgTest(ctx, pkg, testFlags)
1587 if new.has(pkgInAll) && !old.has(pkgInAll|pkgImportsLoaded) {
1588 // We have just marked pkg with pkgInAll, or we have just loaded its
1589 // imports, or both. Now is the time to propagate pkgInAll to the imports.
1590 for _, dep := range pkg.imports {
1591 ld.applyPkgFlags(ctx, dep, pkgInAll)
1595 if new.has(pkgFromRoot) && !old.has(pkgFromRoot|pkgImportsLoaded) {
1596 for _, dep := range pkg.imports {
1597 ld.applyPkgFlags(ctx, dep, pkgFromRoot)
1602 // preloadRootModules loads the module requirements needed to identify the
1603 // selected version of each module providing a package in rootPkgs,
1604 // adding new root modules to the module graph if needed.
1605 func (ld *loader) preloadRootModules(ctx context.Context, rootPkgs []string) (changedBuildList bool) {
1606 needc := make(chan map[module.Version]bool, 1)
1607 needc <- map[module.Version]bool{}
1608 for _, path := range rootPkgs {
1610 ld.work.Add(func() {
1611 // First, try to identify the module containing the package using only roots.
1613 // If the main module is tidy and the package is in "all" — or if we're
1614 // lucky — we can identify all of its imports without actually loading the
1615 // full module graph.
1616 m, _, _, _, err := importFromModules(ctx, path, ld.requirements, nil)
1618 var missing *ImportMissingError
1619 if errors.As(err, &missing) && ld.ResolveMissingImports {
1620 // This package isn't provided by any selected module.
1621 // If we can find it, it will be a new root dependency.
1622 m, err = queryImport(ctx, path, ld.requirements)
1625 // We couldn't identify the root module containing this package.
1626 // Leave it unresolved; we will report it during loading.
1631 // The package is in std or cmd. We don't need to change the root set.
1635 v, ok := ld.requirements.rootSelected(m.Path)
1636 if !ok || v != m.Version {
1637 // We found the requested package in m, but m is not a root, so
1638 // loadModGraph will not load its requirements. We need to promote the
1639 // module to a root to ensure that any other packages this package
1640 // imports are resolved from correct dependency versions.
1642 // (This is the “argument invariant” from
1643 // https://golang.org/design/36460-lazy-module-loading.)
1654 return false // No roots to add.
1657 toAdd := make([]module.Version, 0, len(need))
1658 for m := range need {
1659 toAdd = append(toAdd, m)
1663 rs, err := updateRoots(ctx, ld.requirements.direct, ld.requirements, nil, toAdd, ld.AssumeRootsImported)
1665 // We are missing some root dependency, and for some reason we can't load
1666 // enough of the module dependency graph to add the missing root. Package
1667 // loading is doomed to fail, so fail quickly.
1668 ld.errorf("go: %v\n", err)
1672 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1673 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1674 // set of modules to add to the graph, but adding those modules had no
1675 // effect — either they were already in the graph, or updateRoots did not
1676 // add them as requested.
1677 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1680 ld.requirements = rs
1684 // load loads an individual package.
1685 func (ld *loader) load(ctx context.Context, pkg *loadPkg) {
1687 if ld.requirements.pruning == unpruned {
1689 mg, err = ld.requirements.Graph(ctx)
1691 // We already checked the error from Graph in loadFromRoots and/or
1692 // updateRequirements, so we ignored the error on purpose and we should
1693 // keep trying to push past it.
1695 // However, because mg may be incomplete (and thus may select inaccurate
1696 // versions), we shouldn't use it to load packages. Instead, we pass a nil
1697 // *ModuleGraph, which will cause mg to first try loading from only the
1698 // main module and root dependencies.
1704 pkg.mod, modroot, pkg.dir, pkg.altMods, pkg.err = importFromModules(ctx, pkg.path, ld.requirements, mg)
1708 if MainModules.Contains(pkg.mod.Path) {
1709 // Go ahead and mark pkg as in "all". This provides the invariant that a
1710 // package that is *only* imported by other packages in "all" is always
1711 // marked as such before loading its imports.
1713 // We don't actually rely on that invariant at the moment, but it may
1714 // improve efficiency somewhat and makes the behavior a bit easier to reason
1715 // about (by reducing churn on the flag bits of dependencies), and costs
1716 // essentially nothing (these atomic flag ops are essentially free compared
1717 // to scanning source code for imports).
1718 ld.applyPkgFlags(ctx, pkg, pkgInAll)
1720 if ld.AllowPackage != nil {
1721 if err := ld.AllowPackage(ctx, pkg.path, pkg.mod); err != nil {
1726 pkg.inStd = (search.IsStandardImportPath(pkg.path) && search.InDir(pkg.dir, cfg.GOROOTsrc) != "")
1728 var imports, testImports []string
1730 if cfg.BuildContext.Compiler == "gccgo" && pkg.inStd {
1731 // We can't scan standard packages for gccgo.
1734 imports, testImports, err = scanDir(modroot, pkg.dir, ld.Tags)
1741 pkg.imports = make([]*loadPkg, 0, len(imports))
1742 var importFlags loadPkgFlags
1743 if pkg.flags.has(pkgInAll) {
1744 importFlags = pkgInAll
1746 for _, path := range imports {
1748 // Imports from packages in "std" and "cmd" should resolve using
1749 // GOROOT/src/vendor even when "std" is not the main module.
1750 path = ld.stdVendor(pkg.path, path)
1752 pkg.imports = append(pkg.imports, ld.pkg(ctx, path, importFlags))
1754 pkg.testImports = testImports
1756 ld.applyPkgFlags(ctx, pkg, pkgImportsLoaded)
1759 // pkgTest locates the test of pkg, creating it if needed, and updates its state
1760 // to reflect the given flags.
1762 // pkgTest requires that the imports of pkg have already been loaded (flagged
1763 // with pkgImportsLoaded).
1764 func (ld *loader) pkgTest(ctx context.Context, pkg *loadPkg, testFlags loadPkgFlags) *loadPkg {
1766 panic("pkgTest called on a test package")
1769 createdTest := false
1770 pkg.testOnce.Do(func() {
1771 pkg.test = &loadPkg{
1779 ld.applyPkgFlags(ctx, pkg.test, testFlags)
1785 test.imports = make([]*loadPkg, 0, len(pkg.testImports))
1786 var importFlags loadPkgFlags
1787 if test.flags.has(pkgInAll) {
1788 importFlags = pkgInAll
1790 for _, path := range pkg.testImports {
1792 path = ld.stdVendor(test.path, path)
1794 test.imports = append(test.imports, ld.pkg(ctx, path, importFlags))
1796 pkg.testImports = nil
1797 ld.applyPkgFlags(ctx, test, pkgImportsLoaded)
1799 ld.applyPkgFlags(ctx, test, testFlags)
1805 // stdVendor returns the canonical import path for the package with the given
1806 // path when imported from the standard-library package at parentPath.
1807 func (ld *loader) stdVendor(parentPath, path string) string {
1808 if search.IsStandardImportPath(path) {
1812 if str.HasPathPrefix(parentPath, "cmd") {
1813 if !ld.VendorModulesInGOROOTSrc || !MainModules.Contains("cmd") {
1814 vendorPath := pathpkg.Join("cmd", "vendor", path)
1816 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1820 } else if !ld.VendorModulesInGOROOTSrc || !MainModules.Contains("std") || str.HasPathPrefix(parentPath, "vendor") {
1821 // If we are outside of the 'std' module, resolve imports from within 'std'
1822 // to the vendor directory.
1824 // Do the same for importers beginning with the prefix 'vendor/' even if we
1825 // are *inside* of the 'std' module: the 'vendor/' packages that resolve
1826 // globally from GOROOT/src/vendor (and are listed as part of 'go list std')
1827 // are distinct from the real module dependencies, and cannot import
1828 // internal packages from the real module.
1830 // (Note that although the 'vendor/' packages match the 'std' *package*
1831 // pattern, they are not part of the std *module*, and do not affect
1832 // 'go mod tidy' and similar module commands when working within std.)
1833 vendorPath := pathpkg.Join("vendor", path)
1834 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1839 // Not vendored: resolve from modules.
1843 // computePatternAll returns the list of packages matching pattern "all",
1844 // starting with a list of the import paths for the packages in the main module.
1845 func (ld *loader) computePatternAll() (all []string) {
1846 for _, pkg := range ld.pkgs {
1847 if pkg.flags.has(pkgInAll) && !pkg.isTest() {
1848 all = append(all, pkg.path)
1855 // checkMultiplePaths verifies that a given module path is used as itself
1856 // or as a replacement for another module, but not both at the same time.
1858 // (See https://golang.org/issue/26607 and https://golang.org/issue/34650.)
1859 func (ld *loader) checkMultiplePaths() {
1860 mods := ld.requirements.rootModules
1861 if cached := ld.requirements.graph.Load(); cached != nil {
1862 if mg := cached.(cachedGraph).mg; mg != nil {
1863 mods = mg.BuildList()
1867 firstPath := map[module.Version]string{}
1868 for _, mod := range mods {
1869 src := resolveReplacement(mod)
1870 if prev, ok := firstPath[src]; !ok {
1871 firstPath[src] = mod.Path
1872 } else if prev != mod.Path {
1873 ld.errorf("go: %s@%s used for two different module paths (%s and %s)\n", src.Path, src.Version, prev, mod.Path)
1878 // checkTidyCompatibility emits an error if any package would be loaded from a
1879 // different module under rs than under ld.requirements.
1880 func (ld *loader) checkTidyCompatibility(ctx context.Context, rs *Requirements) {
1881 suggestUpgrade := false
1882 suggestEFlag := false
1883 suggestFixes := func() {
1885 // The user is explicitly ignoring these errors, so don't bother them with
1890 // We print directly to os.Stderr because this information is advice about
1891 // how to fix errors, not actually an error itself.
1892 // (The actual errors should have been logged already.)
1894 fmt.Fprintln(os.Stderr)
1897 if ld.GoVersion != MainModules.GoVersion() {
1898 goFlag = " -go=" + ld.GoVersion
1902 if ld.TidyCompatibleVersion != priorGoVersion(ld.GoVersion) {
1903 compatFlag = " -compat=" + ld.TidyCompatibleVersion
1909 eDesc = ", leaving some packages unresolved"
1912 fmt.Fprintf(os.Stderr, "To upgrade to the versions selected by go %s%s:\n\tgo mod tidy%s -go=%s && go mod tidy%s -go=%s%s\n", ld.TidyCompatibleVersion, eDesc, eFlag, ld.TidyCompatibleVersion, eFlag, ld.GoVersion, compatFlag)
1913 } else if suggestEFlag {
1914 // If some packages are missing but no package is upgraded, then we
1915 // shouldn't suggest upgrading to the Go 1.16 versions explicitly — that
1916 // wouldn't actually fix anything for Go 1.16 users, and *would* break
1917 // something for Go 1.17 users.
1918 fmt.Fprintf(os.Stderr, "To proceed despite packages unresolved in go %s:\n\tgo mod tidy -e%s%s\n", ld.TidyCompatibleVersion, goFlag, compatFlag)
1921 fmt.Fprintf(os.Stderr, "If reproducibility with go %s is not needed:\n\tgo mod tidy%s -compat=%s\n", ld.TidyCompatibleVersion, goFlag, ld.GoVersion)
1923 // TODO(#46141): Populate the linked wiki page.
1924 fmt.Fprintf(os.Stderr, "For other options, see:\n\thttps://golang.org/doc/modules/pruning\n")
1927 mg, err := rs.Graph(ctx)
1929 ld.errorf("go: error loading go %s module graph: %v\n", ld.TidyCompatibleVersion, err)
1934 // Re-resolve packages in parallel.
1936 // We re-resolve each package — rather than just checking versions — to ensure
1937 // that we have fetched module source code (and, importantly, checksums for
1938 // that source code) for all modules that are necessary to ensure that imports
1939 // are unambiguous. That also produces clearer diagnostics, since we can say
1940 // exactly what happened to the package if it became ambiguous or disappeared
1943 // We re-resolve the packages in parallel because this process involves disk
1944 // I/O to check for package sources, and because the process of checking for
1945 // ambiguous imports may require us to download additional modules that are
1946 // otherwise pruned out in Go 1.17 — we don't want to block progress on other
1947 // packages while we wait for a single new download.
1948 type mismatch struct {
1952 mismatchMu := make(chan map[*loadPkg]mismatch, 1)
1953 mismatchMu <- map[*loadPkg]mismatch{}
1954 for _, pkg := range ld.pkgs {
1955 if pkg.mod.Path == "" && pkg.err == nil {
1956 // This package is from the standard library (which does not vary based on
1957 // the module graph).
1962 ld.work.Add(func() {
1963 mod, _, _, _, err := importFromModules(ctx, pkg.path, rs, mg)
1965 mismatches := <-mismatchMu
1966 mismatches[pkg] = mismatch{mod: mod, err: err}
1967 mismatchMu <- mismatches
1973 mismatches := <-mismatchMu
1974 if len(mismatches) == 0 {
1975 // Since we're running as part of 'go mod tidy', the roots of the module
1976 // graph should contain only modules that are relevant to some package in
1977 // the package graph. We checked every package in the package graph and
1978 // didn't find any mismatches, so that must mean that all of the roots of
1979 // the module graph are also consistent.
1981 // If we're wrong, Go 1.16 in -mod=readonly mode will error out with
1982 // "updates to go.mod needed", which would be very confusing. So instead,
1983 // we'll double-check that our reasoning above actually holds — if it
1984 // doesn't, we'll emit an internal error and hopefully the user will report
1986 for _, m := range ld.requirements.rootModules {
1987 if v := mg.Selected(m.Path); v != m.Version {
1988 fmt.Fprintln(os.Stderr)
1989 base.Fatalf("go: internal error: failed to diagnose selected-version mismatch for module %s: go %s selects %s, but go %s selects %s\n\tPlease report this at https://golang.org/issue.", m.Path, ld.GoVersion, m.Version, ld.TidyCompatibleVersion, v)
1995 // Iterate over the packages (instead of the mismatches map) to emit errors in
1996 // deterministic order.
1997 for _, pkg := range ld.pkgs {
1998 mismatch, ok := mismatches[pkg]
2004 // We already did (or will) report an error for the package itself,
2005 // so don't report a duplicate (and more vebose) error for its test.
2006 if _, ok := mismatches[pkg.testOf]; !ok {
2007 base.Fatalf("go: internal error: mismatch recorded for test %s, but not its non-test package", pkg.path)
2013 case mismatch.err != nil:
2014 // pkg resolved successfully, but errors out using the requirements in rs.
2016 // This could occur because the import is provided by a single root (and
2017 // is thus unambiguous in a main module with a pruned module graph) and
2018 // also one or more transitive dependencies (and is ambiguous with an
2021 // It could also occur because some transitive dependency upgrades the
2022 // module that previously provided the package to a version that no
2023 // longer does, or to a version for which the module source code (but
2024 // not the go.mod file in isolation) has a checksum error.
2025 if missing := (*ImportMissingError)(nil); errors.As(mismatch.err, &missing) {
2026 selected := module.Version{
2028 Version: mg.Selected(pkg.mod.Path),
2030 ld.errorf("%s loaded from %v,\n\tbut go %s would fail to locate it in %s\n", pkg.stackText(), pkg.mod, ld.TidyCompatibleVersion, selected)
2032 if ambiguous := (*AmbiguousImportError)(nil); errors.As(mismatch.err, &ambiguous) {
2033 // TODO: Is this check needed?
2035 ld.errorf("%s loaded from %v,\n\tbut go %s would fail to locate it:\n\t%v\n", pkg.stackText(), pkg.mod, ld.TidyCompatibleVersion, mismatch.err)
2040 // Even if we press ahead with the '-e' flag, the older version will
2041 // error out in readonly mode if it thinks the go.mod file contains
2042 // any *explicit* dependency that is not at its selected version,
2043 // even if that dependency is not relevant to any package being loaded.
2045 // We check for that condition here. If all of the roots are consistent
2046 // the '-e' flag suffices, but otherwise we need to suggest an upgrade.
2047 if !suggestUpgrade {
2048 for _, m := range ld.requirements.rootModules {
2049 if v := mg.Selected(m.Path); v != m.Version {
2050 suggestUpgrade = true
2056 case pkg.err != nil:
2057 // pkg had an error in with a pruned module graph (presumably suppressed
2058 // with the -e flag), but the error went away using an unpruned graph.
2060 // This is possible, if, say, the import is unresolved in the pruned graph
2061 // (because the "latest" version of each candidate module either is
2062 // unavailable or does not contain the package), but is resolved in the
2063 // unpruned graph due to a newer-than-latest dependency that is normally
2066 // This could also occur if the source code for the module providing the
2067 // package in the pruned graph has a checksum error, but the unpruned
2068 // graph upgrades that module to a version with a correct checksum.
2070 // pkg.err should have already been logged elsewhere — along with a
2071 // stack trace — so log only the import path and non-error info here.
2072 suggestUpgrade = true
2073 ld.errorf("%s failed to load from any module,\n\tbut go %s would load it from %v\n", pkg.path, ld.TidyCompatibleVersion, mismatch.mod)
2075 case pkg.mod != mismatch.mod:
2076 // The package is loaded successfully by both Go versions, but from a
2077 // different module in each. This could lead to subtle (and perhaps even
2078 // unnoticed!) variations in behavior between builds with different
2080 suggestUpgrade = true
2081 ld.errorf("%s loaded from %v,\n\tbut go %s would select %v\n", pkg.stackText(), pkg.mod, ld.TidyCompatibleVersion, mismatch.mod.Version)
2084 base.Fatalf("go: internal error: mismatch recorded for package %s, but no differences found", pkg.path)
2092 // scanDir is like imports.ScanDir but elides known magic imports from the list,
2093 // so that we do not go looking for packages that don't really exist.
2095 // The standard magic import is "C", for cgo.
2097 // The only other known magic imports are appengine and appengine/*.
2098 // These are so old that they predate "go get" and did not use URL-like paths.
2099 // Most code today now uses google.golang.org/appengine instead,
2100 // but not all code has been so updated. When we mostly ignore build tags
2101 // during "go vendor", we look into "// +build appengine" files and
2102 // may see these legacy imports. We drop them so that the module
2103 // search does not look for modules to try to satisfy them.
2104 func scanDir(modroot string, dir string, tags map[string]bool) (imports_, testImports []string, err error) {
2105 if ip, mierr := modindex.GetPackage(modroot, dir); mierr == nil {
2106 imports_, testImports, err = ip.ScanDir(tags)
2108 } else if !errors.Is(mierr, modindex.ErrNotIndexed) {
2109 return nil, nil, mierr
2112 imports_, testImports, err = imports.ScanDir(dir, tags)
2115 filter := func(x []string) []string {
2117 for _, pkg := range x {
2118 if pkg != "C" && pkg != "appengine" && !strings.HasPrefix(pkg, "appengine/") &&
2119 pkg != "appengine_internal" && !strings.HasPrefix(pkg, "appengine_internal/") {
2127 return filter(imports_), filter(testImports), err
2130 // buildStacks computes minimal import stacks for each package,
2131 // for use in error messages. When it completes, packages that
2132 // are part of the original root set have pkg.stack == nil,
2133 // and other packages have pkg.stack pointing at the next
2134 // package up the import stack in their minimal chain.
2135 // As a side effect, buildStacks also constructs ld.pkgs,
2136 // the list of all packages loaded.
2137 func (ld *loader) buildStacks() {
2138 if len(ld.pkgs) > 0 {
2139 panic("buildStacks")
2141 for _, pkg := range ld.roots {
2142 pkg.stack = pkg // sentinel to avoid processing in next loop
2143 ld.pkgs = append(ld.pkgs, pkg)
2145 for i := 0; i < len(ld.pkgs); i++ { // not range: appending to ld.pkgs in loop
2147 for _, next := range pkg.imports {
2148 if next.stack == nil {
2150 ld.pkgs = append(ld.pkgs, next)
2153 if next := pkg.test; next != nil && next.stack == nil {
2155 ld.pkgs = append(ld.pkgs, next)
2158 for _, pkg := range ld.roots {
2163 // stackText builds the import stack text to use when
2164 // reporting an error in pkg. It has the general form
2169 // other2.test imports
2171 func (pkg *loadPkg) stackText() string {
2172 var stack []*loadPkg
2173 for p := pkg; p != nil; p = p.stack {
2174 stack = append(stack, p)
2177 var buf bytes.Buffer
2178 for i := len(stack) - 1; i >= 0; i-- {
2180 fmt.Fprint(&buf, p.path)
2181 if p.testOf != nil {
2182 fmt.Fprint(&buf, ".test")
2185 if stack[i-1].testOf == p {
2186 fmt.Fprint(&buf, " tested by\n\t")
2188 fmt.Fprint(&buf, " imports\n\t")
2195 // why returns the text to use in "go mod why" output about the given package.
2196 // It is less ornate than the stackText but contains the same information.
2197 func (pkg *loadPkg) why() string {
2198 var buf strings.Builder
2199 var stack []*loadPkg
2200 for p := pkg; p != nil; p = p.stack {
2201 stack = append(stack, p)
2204 for i := len(stack) - 1; i >= 0; i-- {
2206 if p.testOf != nil {
2207 fmt.Fprintf(&buf, "%s.test\n", p.testOf.path)
2209 fmt.Fprintf(&buf, "%s\n", p.path)
2215 // Why returns the "go mod why" output stanza for the given package,
2216 // without the leading # comment.
2217 // The package graph must have been loaded already, usually by LoadPackages.
2218 // If there is no reason for the package to be in the current build,
2219 // Why returns an empty string.
2220 func Why(path string) string {
2221 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
2228 // WhyDepth returns the number of steps in the Why listing.
2229 // If there is no reason for the package to be in the current build,
2230 // WhyDepth returns 0.
2231 func WhyDepth(path string) int {
2233 pkg, _ := loaded.pkgCache.Get(path).(*loadPkg)
2234 for p := pkg; p != nil; p = p.stack {