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 we implement lazy loading, we will record the modules providing packages
44 // in "all" even when we are only loading individual packages, so we set the
45 // pkgInAll flag regardless of the whether the "all" pattern is a root.
46 // (This is necessary to maintain the “import invariant” described in
47 // https://golang.org/design/36460-lazy-module-loading.)
49 // Because "go mod vendor" prunes out the tests of vendored packages, the
50 // behavior of the "all" pattern with -mod=vendor in Go 1.11–1.15 is the same
51 // as the "all" pattern (regardless of the -mod flag) in 1.16+.
52 // The loader uses the GoVersion parameter to determine whether the "all"
53 // pattern should close over tests (as in Go 1.11–1.15) or stop at only those
54 // packages transitively imported by the packages and tests in the main module
55 // ("all" in Go 1.16+ and "go mod vendor" in Go 1.11+).
57 // Note that it is possible for a loaded package NOT to be in "all" even when we
58 // are loading the "all" pattern. For example, packages that are transitive
59 // dependencies of other roots named on the command line must be loaded, but are
60 // not in "all". (The mod_notall test illustrates this behavior.)
61 // Similarly, if the LoadTests flag is set but the "all" pattern does not close
62 // over test dependencies, then when we load the test of a package that is in
63 // "all" but outside the main module, the dependencies of that test will not
64 // necessarily themselves be in "all". (That configuration does not arise in Go
65 // 1.11–1.15, but it will be possible in Go 1.16+.)
67 // Loading proceeds from the roots, using a parallel work-queue with a limit on
68 // the amount of active work (to avoid saturating disks, CPU cores, and/or
69 // network connections). Each package is added to the queue the first time it is
70 // imported by another package. When we have finished identifying the imports of
71 // a package, we add the test for that package if it is needed. A test may be
73 // - the package matches a root pattern and tests of the roots were requested, or
74 // - the package is in the main module and the "all" pattern is requested
75 // (because the "all" pattern includes the dependencies of tests in the main
77 // - the package is in "all" and the definition of "all" we are using includes
78 // dependencies of tests (as is the case in Go ≤1.15).
80 // After all available packages have been loaded, we examine the results to
81 // identify any requested or imported packages that are still missing, and if
82 // so, which modules we could add to the module graph in order to make the
83 // missing packages available. We add those to the module graph and iterate,
84 // until either all packages resolve successfully or we cannot identify any
85 // module that would resolve any remaining missing package.
87 // If the main module is “tidy” (that is, if "go mod tidy" is a no-op for it)
88 // and all requested packages are in "all", then loading completes in a single
90 // TODO(bcmills): We should also be able to load in a single iteration if the
91 // requested packages all come from modules that are themselves tidy, regardless
92 // of whether those packages are in "all". Today, that requires two iterations
93 // if those packages are not found in existing dependencies of the main module.
113 "cmd/go/internal/base"
114 "cmd/go/internal/cfg"
115 "cmd/go/internal/fsys"
116 "cmd/go/internal/imports"
117 "cmd/go/internal/modfetch"
118 "cmd/go/internal/mvs"
119 "cmd/go/internal/par"
120 "cmd/go/internal/search"
121 "cmd/go/internal/str"
123 "golang.org/x/mod/module"
124 "golang.org/x/mod/semver"
127 // loaded is the most recently-used package loader.
128 // It holds details about individual packages.
130 // This variable should only be accessed directly in top-level exported
131 // functions. All other functions that require or produce a *loader should pass
132 // or return it as an explicit parameter.
135 // PackageOpts control the behavior of the LoadPackages function.
136 type PackageOpts struct {
137 // GoVersion is the Go version to which the go.mod file should be updated
138 // after packages have been loaded.
140 // An empty GoVersion means to use the Go version already specified in the
141 // main module's go.mod file, or the latest Go version if there is no main
145 // Tags are the build tags in effect (as interpreted by the
146 // cmd/go/internal/imports package).
147 // If nil, treated as equivalent to imports.Tags().
150 // Tidy, if true, requests that the build list and go.sum file be reduced to
151 // the minimial dependencies needed to reproducibly reload the requested
155 // TidyCompatibleVersion is the oldest Go version that must be able to
156 // reproducibly reload the requested packages.
158 // If empty, the compatible version is the Go version immediately prior to the
159 // 'go' version listed in the go.mod file.
160 TidyCompatibleVersion string
162 // VendorModulesInGOROOTSrc indicates that if we are within a module in
163 // GOROOT/src, packages in the module's vendor directory should be resolved as
164 // actual module dependencies (instead of standard-library packages).
165 VendorModulesInGOROOTSrc bool
167 // ResolveMissingImports indicates that we should attempt to add module
168 // dependencies as needed to resolve imports of packages that are not found.
170 // For commands that support the -mod flag, resolving imports may still fail
171 // if the flag is set to "readonly" (the default) or "vendor".
172 ResolveMissingImports bool
174 // AssumeRootsImported indicates that the transitive dependencies of the root
175 // packages should be treated as if those roots will be imported by the main
177 AssumeRootsImported bool
179 // AllowPackage, if non-nil, is called after identifying the module providing
180 // each package. If AllowPackage returns a non-nil error, that error is set
181 // for the package, and the imports and test of that package will not be
184 // AllowPackage may be invoked concurrently by multiple goroutines,
185 // and may be invoked multiple times for a given package path.
186 AllowPackage func(ctx context.Context, path string, mod module.Version) error
188 // LoadTests loads the test dependencies of each package matching a requested
189 // pattern. If ResolveMissingImports is also true, test dependencies will be
190 // resolved if missing.
193 // UseVendorAll causes the "all" package pattern to be interpreted as if
194 // running "go mod vendor" (or building with "-mod=vendor").
196 // This is a no-op for modules that declare 'go 1.16' or higher, for which this
197 // is the default (and only) interpretation of the "all" pattern in module mode.
200 // AllowErrors indicates that LoadPackages should not terminate the process if
204 // SilencePackageErrors indicates that LoadPackages should not print errors
205 // that occur while matching or loading packages, and should not terminate the
206 // process if such an error occurs.
208 // Errors encountered in the module graph will still be reported.
210 // The caller may retrieve the silenced package errors using the Lookup
211 // function, and matching errors are still populated in the Errs field of the
212 // associated search.Match.)
213 SilencePackageErrors bool
215 // SilenceMissingStdImports indicates that LoadPackages should not print
216 // errors or terminate the process if an imported package is missing, and the
217 // import path looks like it might be in the standard library (perhaps in a
219 SilenceMissingStdImports bool
221 // SilenceNoGoErrors indicates that LoadPackages should not print
222 // imports.ErrNoGo errors.
223 // This allows the caller to invoke LoadPackages (and report other errors)
224 // without knowing whether the requested packages exist for the given tags.
226 // Note that if a requested package does not exist *at all*, it will fail
227 // during module resolution and the error will not be suppressed.
228 SilenceNoGoErrors bool
230 // SilenceUnmatchedWarnings suppresses the warnings normally emitted for
231 // patterns that did not match any packages.
232 SilenceUnmatchedWarnings bool
235 // LoadPackages identifies the set of packages matching the given patterns and
236 // loads the packages in the import graph rooted at that set.
237 func LoadPackages(ctx context.Context, opts PackageOpts, patterns ...string) (matches []*search.Match, loadedPackages []string) {
238 if opts.Tags == nil {
239 opts.Tags = imports.Tags()
242 patterns = search.CleanPatterns(patterns)
243 matches = make([]*search.Match, 0, len(patterns))
244 allPatternIsRoot := false
245 for _, pattern := range patterns {
246 matches = append(matches, search.NewMatch(pattern))
247 if pattern == "all" {
248 allPatternIsRoot = true
252 updateMatches := func(rs *Requirements, ld *loader) {
253 for _, m := range matches {
256 // Evaluate list of file system directories on first iteration.
258 matchLocalDirs(ctx, m, rs)
261 // Make a copy of the directory list and translate to import paths.
262 // Note that whether a directory corresponds to an import path
263 // changes as the build list is updated, and a directory can change
264 // from not being in the build list to being in it and back as
265 // the exact version of a particular module increases during
266 // the loader iterations.
268 for _, dir := range m.Dirs {
269 pkg, err := resolveLocalPackage(ctx, dir, rs)
271 if !m.IsLiteral() && (err == errPkgIsBuiltin || err == errPkgIsGorootSrc) {
272 continue // Don't include "builtin" or GOROOT/src in wildcard patterns.
275 // If we're outside of a module, ensure that the failure mode
286 m.Pkgs = append(m.Pkgs, pkg)
290 m.Pkgs = []string{m.Pattern()}
292 case strings.Contains(m.Pattern(), "..."):
294 mg, err := rs.Graph(ctx)
296 // The module graph is (or may be) incomplete — perhaps we failed to
297 // load the requirements of some module. This is an error in matching
298 // the patterns to packages, because we may be missing some packages
299 // or we may erroneously match packages in the wrong versions of
300 // modules. However, for cases like 'go list -e', the error should not
301 // necessarily prevent us from loading the packages we could find.
302 m.Errs = append(m.Errs, err)
304 matchPackages(ctx, m, opts.Tags, includeStd, mg.BuildList())
306 case m.Pattern() == "all":
308 // The initial roots are the packages in the main module.
309 // loadFromRoots will expand that to "all".
311 matchPackages(ctx, m, opts.Tags, omitStd, MainModules.Versions())
313 // Starting with the packages in the main module,
314 // enumerate the full list of "all".
315 m.Pkgs = ld.computePatternAll()
318 case m.Pattern() == "std" || m.Pattern() == "cmd":
320 m.MatchPackages() // Locate the packages within GOROOT/src.
324 panic(fmt.Sprintf("internal error: modload missing case for pattern %s", m.Pattern()))
329 initialRS, _ := loadModFile(ctx) // Ignore needCommit — we're going to commit at the end regardless.
331 ld := loadFromRoots(ctx, loaderParams{
333 requirements: initialRS,
335 allPatternIsRoot: allPatternIsRoot,
337 listRoots: func(rs *Requirements) (roots []string) {
338 updateMatches(rs, nil)
339 for _, m := range matches {
340 roots = append(roots, m.Pkgs...)
346 // One last pass to finalize wildcards.
347 updateMatches(ld.requirements, ld)
349 // List errors in matching patterns (such as directory permission
350 // errors for wildcard patterns).
351 if !ld.SilencePackageErrors {
352 for _, match := range matches {
353 for _, err := range match.Errs {
354 ld.errorf("%v\n", err)
360 if !opts.SilenceUnmatchedWarnings {
361 search.WarnUnmatched(matches)
366 mg, _ := ld.requirements.Graph(ctx)
368 for _, m := range initialRS.rootModules {
370 if ld.requirements.depth == eager {
371 // m is unused if it was dropped from the module graph entirely. If it
372 // was only demoted from direct to indirect, it may still be in use via
373 // a transitive import.
374 unused = mg.Selected(m.Path) == "none"
376 // m is unused if it was dropped from the roots. If it is still present
377 // as a transitive dependency, that transitive dependency is not needed
378 // by any package or test in the main module.
379 _, ok := ld.requirements.rootSelected(m.Path)
383 fmt.Fprintf(os.Stderr, "unused %s\n", m.Path)
388 keep := keepSums(ctx, ld, ld.requirements, loadedZipSumsOnly)
389 if compatDepth := modDepthFromGoVersion(ld.TidyCompatibleVersion); compatDepth != ld.requirements.depth {
390 compatRS := newRequirements(compatDepth, ld.requirements.rootModules, ld.requirements.direct)
391 ld.checkTidyCompatibility(ctx, compatRS)
393 for m := range keepSums(ctx, ld, compatRS, loadedZipSumsOnly) {
399 modfetch.TrimGoSum(keep)
401 // commitRequirements below will also call WriteGoSum, but the "keep" map
402 // we have here could be strictly larger: commitRequirements only commits
403 // loaded.requirements, but here we may have also loaded (and want to
404 // preserve checksums for) additional entities from compatRS, which are
405 // only needed for compatibility with ld.TidyCompatibleVersion.
406 if err := modfetch.WriteGoSum(keep, mustHaveCompleteRequirements()); err != nil {
407 base.Fatalf("go: %v", err)
412 // Success! Update go.mod and go.sum (if needed) and return the results.
414 commitRequirements(ctx, loaded.GoVersion, loaded.requirements)
416 for _, pkg := range ld.pkgs {
418 loadedPackages = append(loadedPackages, pkg.path)
421 sort.Strings(loadedPackages)
422 return matches, loadedPackages
425 // matchLocalDirs is like m.MatchDirs, but tries to avoid scanning directories
426 // outside of the standard library and active modules.
427 func matchLocalDirs(ctx context.Context, m *search.Match, rs *Requirements) {
429 panic(fmt.Sprintf("internal error: resolveLocalDirs on non-local pattern %s", m.Pattern()))
432 if i := strings.Index(m.Pattern(), "..."); i >= 0 {
433 // The pattern is local, but it is a wildcard. Its packages will
434 // only resolve to paths if they are inside of the standard
435 // library, the main module, or some dependency of the main
436 // module. Verify that before we walk the filesystem: a filesystem
437 // walk in a directory like /var or /etc can be very expensive!
438 dir := filepath.Dir(filepath.Clean(m.Pattern()[:i+3]))
440 if !filepath.IsAbs(dir) {
441 absDir = filepath.Join(base.Cwd(), dir)
443 if search.InDir(absDir, cfg.GOROOTsrc) == "" && search.InDir(absDir, ModRoot()) == "" && pathInModuleCache(ctx, absDir, rs) == "" {
445 m.AddError(fmt.Errorf("directory prefix %s outside available modules", base.ShortPath(absDir)))
450 m.MatchDirs(modRoots)
453 // resolveLocalPackage resolves a filesystem path to a package path.
454 func resolveLocalPackage(ctx context.Context, dir string, rs *Requirements) (string, error) {
456 if filepath.IsAbs(dir) {
457 absDir = filepath.Clean(dir)
459 absDir = filepath.Join(base.Cwd(), dir)
462 bp, err := cfg.BuildContext.ImportDir(absDir, 0)
463 if err != nil && (bp == nil || len(bp.IgnoredGoFiles) == 0) {
464 // golang.org/issue/32917: We should resolve a relative path to a
465 // package path only if the relative path actually contains the code
468 // If the named directory does not exist or contains no Go files,
469 // the package does not exist.
470 // Other errors may affect package loading, but not resolution.
471 if _, err := fsys.Stat(absDir); err != nil {
472 if os.IsNotExist(err) {
473 // Canonicalize OS-specific errors to errDirectoryNotFound so that error
474 // messages will be easier for users to search for.
475 return "", &fs.PathError{Op: "stat", Path: absDir, Err: errDirectoryNotFound}
479 if _, noGo := err.(*build.NoGoError); noGo {
480 // A directory that does not contain any Go source files — even ignored
481 // ones! — is not a Go package, and we can't resolve it to a package
482 // path because that path could plausibly be provided by some other
485 // Any other error indicates that the package “exists” (at least in the
486 // sense that it cannot exist in any other module), but has some other
487 // problem (such as a syntax error).
492 for _, mod := range MainModules.Versions() {
493 modRoot := MainModules.ModRoot(mod)
494 if modRoot != "" && absDir == modRoot {
495 if absDir == cfg.GOROOTsrc {
496 return "", errPkgIsGorootSrc
498 return MainModules.PathPrefix(mod), nil
502 // Note: The checks for @ here are just to avoid misinterpreting
503 // the module cache directories (formerly GOPATH/src/mod/foo@v1.5.2/bar).
504 // It's not strictly necessary but helpful to keep the checks.
505 var pkgNotFoundErr error
506 pkgNotFoundLongestPrefix := ""
507 for _, mainModule := range MainModules.Versions() {
508 modRoot := MainModules.ModRoot(mainModule)
509 if modRoot != "" && strings.HasPrefix(absDir, modRoot+string(filepath.Separator)) && !strings.Contains(absDir[len(modRoot):], "@") {
510 suffix := filepath.ToSlash(absDir[len(modRoot):])
511 if strings.HasPrefix(suffix, "/vendor/") {
512 if cfg.BuildMod != "vendor" {
513 return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
517 pkg := strings.TrimPrefix(suffix, "/vendor/")
518 if _, ok := vendorPkgModule[pkg]; !ok {
519 return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
524 mainModulePrefix := MainModules.PathPrefix(mainModule)
525 if mainModulePrefix == "" {
526 pkg := strings.TrimPrefix(suffix, "/")
527 if pkg == "builtin" {
528 // "builtin" is a pseudo-package with a real source file.
529 // It's not included in "std", so it shouldn't resolve from "."
530 // within module "std" either.
531 return "", errPkgIsBuiltin
536 pkg := mainModulePrefix + suffix
537 if _, ok, err := dirInModule(pkg, mainModulePrefix, modRoot, true); err != nil {
540 // This main module could contain the directory but doesn't. Other main
541 // modules might contain the directory, so wait till we finish the loop
542 // to see if another main module contains directory. But if not,
544 if len(mainModulePrefix) > len(pkgNotFoundLongestPrefix) {
545 pkgNotFoundLongestPrefix = mainModulePrefix
546 pkgNotFoundErr = &PackageNotInModuleError{Mod: mainModule, Pattern: pkg}
554 if pkgNotFoundErr != nil {
555 return "", pkgNotFoundErr
558 if sub := search.InDir(absDir, cfg.GOROOTsrc); sub != "" && sub != "." && !strings.Contains(sub, "@") {
559 pkg := filepath.ToSlash(sub)
560 if pkg == "builtin" {
561 return "", errPkgIsBuiltin
566 pkg := pathInModuleCache(ctx, absDir, rs)
568 return "", fmt.Errorf("directory %s outside available modules", base.ShortPath(absDir))
574 errDirectoryNotFound = errors.New("directory not found")
575 errPkgIsGorootSrc = errors.New("GOROOT/src is not an importable package")
576 errPkgIsBuiltin = errors.New(`"builtin" is a pseudo-package, not an importable package`)
579 // pathInModuleCache returns the import path of the directory dir,
580 // if dir is in the module cache copy of a module in our build list.
581 func pathInModuleCache(ctx context.Context, dir string, rs *Requirements) string {
582 tryMod := func(m module.Version) (string, bool) {
585 if repl := Replacement(m); repl.Path != "" && repl.Version == "" {
587 if !filepath.IsAbs(root) {
588 root = filepath.Join(ModRoot(), root)
590 } else if repl.Path != "" {
591 root, err = modfetch.DownloadDir(repl)
593 root, err = modfetch.DownloadDir(m)
599 sub := search.InDir(dir, root)
603 sub = filepath.ToSlash(sub)
604 if strings.Contains(sub, "/vendor/") || strings.HasPrefix(sub, "vendor/") || strings.Contains(sub, "@") {
608 return path.Join(m.Path, filepath.ToSlash(sub)), true
611 if rs.depth == lazy {
612 for _, m := range rs.rootModules {
613 if v, _ := rs.rootSelected(m.Path); v != m.Version {
614 continue // m is a root, but we have a higher root for the same path.
616 if importPath, ok := tryMod(m); ok {
617 // checkMultiplePaths ensures that a module can be used for at most one
618 // requirement, so this must be it.
624 // None of the roots contained dir, or we're in eager mode and want to load
625 // the full module graph more aggressively. Either way, check the full graph
626 // to see if the directory is a non-root dependency.
628 // If the roots are not consistent with the full module graph, the selected
629 // versions of root modules may differ from what we already checked above.
630 // Re-check those paths too.
632 mg, _ := rs.Graph(ctx)
633 var importPath string
634 for _, m := range mg.BuildList() {
636 importPath, found = tryMod(m)
644 // ImportFromFiles adds modules to the build list as needed
645 // to satisfy the imports in the named Go source files.
647 // Errors in missing dependencies are silenced.
649 // TODO(bcmills): Silencing errors seems off. Take a closer look at this and
650 // figure out what the error-reporting actually ought to be.
651 func ImportFromFiles(ctx context.Context, gofiles []string) {
652 rs := LoadModFile(ctx)
654 tags := imports.Tags()
655 imports, testImports, err := imports.ScanFiles(gofiles, tags)
657 base.Fatalf("go: %v", err)
660 loaded = loadFromRoots(ctx, loaderParams{
661 PackageOpts: PackageOpts{
663 ResolveMissingImports: true,
664 SilencePackageErrors: true,
667 listRoots: func(*Requirements) (roots []string) {
668 roots = append(roots, imports...)
669 roots = append(roots, testImports...)
673 commitRequirements(ctx, loaded.GoVersion, loaded.requirements)
676 // DirImportPath returns the effective import path for dir,
677 // provided it is within a main module, or else returns ".".
678 func (mms *MainModuleSet) DirImportPath(ctx context.Context, dir string) (path string, m module.Version) {
680 return ".", module.Version{}
682 LoadModFile(ctx) // Sets targetPrefix.
684 if !filepath.IsAbs(dir) {
685 dir = filepath.Join(base.Cwd(), dir)
687 dir = filepath.Clean(dir)
690 var longestPrefix string
691 var longestPrefixPath string
692 var longestPrefixVersion module.Version
693 for _, v := range mms.Versions() {
694 modRoot := mms.ModRoot(v)
696 return mms.PathPrefix(v), v
698 if strings.HasPrefix(dir, modRoot+string(filepath.Separator)) {
699 pathPrefix := MainModules.PathPrefix(v)
700 if pathPrefix > longestPrefix {
701 longestPrefix = pathPrefix
702 longestPrefixVersion = v
703 suffix := filepath.ToSlash(dir[len(modRoot):])
704 if strings.HasPrefix(suffix, "/vendor/") {
705 longestPrefixPath = strings.TrimPrefix(suffix, "/vendor/")
707 longestPrefixPath = mms.PathPrefix(v) + suffix
711 if len(longestPrefix) > 0 {
712 return longestPrefixPath, longestPrefixVersion
715 return ".", module.Version{}
718 // TargetPackages returns the list of packages in the target (top-level) module
719 // matching pattern, which may be relative to the working directory, under all
720 // build tag settings.
721 func TargetPackages(ctx context.Context, pattern string) *search.Match {
722 // TargetPackages is relative to the main module, so ensure that the main
723 // module is a thing that can contain packages.
724 LoadModFile(ctx) // Sets Target.
725 ModRoot() // Emits an error if Target cannot contain packages.
727 m := search.NewMatch(pattern)
728 matchPackages(ctx, m, imports.AnyTags(), omitStd, MainModules.Versions())
732 // ImportMap returns the actual package import path
733 // for an import path found in source code.
734 // If the given import path does not appear in the source code
735 // for the packages that have been loaded, ImportMap returns the empty string.
736 func ImportMap(path string) string {
737 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
744 // PackageDir returns the directory containing the source code
745 // for the package named by the import path.
746 func PackageDir(path string) string {
747 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
754 // PackageModule returns the module providing the package named by the import path.
755 func PackageModule(path string) module.Version {
756 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
758 return module.Version{}
763 // PackageImports returns the imports for the package named by the import path.
764 // Test imports will be returned as well if tests were loaded for the package
765 // (i.e., if "all" was loaded or if LoadTests was set and the path was matched
766 // by a command line argument). PackageImports will return nil for
767 // unknown package paths.
768 func PackageImports(path string) (imports, testImports []string) {
769 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
773 imports = make([]string, len(pkg.imports))
774 for i, p := range pkg.imports {
778 testImports = make([]string, len(pkg.test.imports))
779 for i, p := range pkg.test.imports {
780 testImports[i] = p.path
783 return imports, testImports
786 // Lookup returns the source directory, import path, and any loading error for
787 // the package at path as imported from the package in parentDir.
788 // Lookup requires that one of the Load functions in this package has already
790 func Lookup(parentPath string, parentIsStd bool, path string) (dir, realPath string, err error) {
792 panic("Lookup called with empty package path")
796 path = loaded.stdVendor(parentPath, path)
798 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
800 // The loader should have found all the relevant paths.
801 // There are a few exceptions, though:
802 // - during go list without -test, the p.Resolve calls to process p.TestImports and p.XTestImports
803 // end up here to canonicalize the import paths.
804 // - during any load, non-loaded packages like "unsafe" end up here.
805 // - during any load, build-injected dependencies like "runtime/cgo" end up here.
806 // - because we ignore appengine/* in the module loader,
807 // the dependencies of any actual appengine/* library end up here.
808 dir := findStandardImportPath(path)
810 return dir, path, nil
812 return "", "", errMissing
814 return pkg.dir, pkg.path, pkg.err
817 // A loader manages the process of loading information about
818 // the required packages for a particular build,
819 // checking that the packages are available in the module set,
820 // and updating the module set if needed.
824 // allClosesOverTests indicates whether the "all" pattern includes
825 // dependencies of tests outside the main module (as in Go 1.11–1.15).
826 // (Otherwise — as in Go 1.16+ — the "all" pattern includes only the packages
827 // transitively *imported by* the packages and tests in the main module.)
828 allClosesOverTests bool
832 // reset on each iteration
834 pkgCache *par.Cache // package path (string) → *loadPkg
835 pkgs []*loadPkg // transitive closure of loaded packages and tests; populated in buildStacks
838 // loaderParams configure the packages loaded by, and the properties reported
839 // by, a loader instance.
840 type loaderParams struct {
842 requirements *Requirements
844 allPatternIsRoot bool // Is the "all" pattern an additional root?
846 listRoots func(rs *Requirements) []string
849 func (ld *loader) reset() {
851 case <-ld.work.Idle():
853 panic("loader.reset when not idle")
857 ld.pkgCache = new(par.Cache)
861 // errorf reports an error via either os.Stderr or base.Errorf,
862 // according to whether ld.AllowErrors is set.
863 func (ld *loader) errorf(format string, args ...interface{}) {
865 fmt.Fprintf(os.Stderr, format, args...)
867 base.Errorf(format, args...)
871 // A loadPkg records information about a single loaded package.
872 type loadPkg struct {
873 // Populated at construction time:
874 path string // import path
877 // Populated at construction time and updated by (*loader).applyPkgFlags:
878 flags atomicLoadPkgFlags
880 // Populated by (*loader).load:
881 mod module.Version // module providing package
882 dir string // directory containing source code
883 err error // error loading package
884 imports []*loadPkg // packages imported by this one
885 testImports []string // test-only imports, saved for use by pkg.test.
888 // Populated by (*loader).pkgTest:
892 // Populated by postprocessing in (*loader).buildStacks:
893 stack *loadPkg // package importing this one in minimal import stack for this pkg
896 // loadPkgFlags is a set of flags tracking metadata about a package.
897 type loadPkgFlags int8
900 // pkgInAll indicates that the package is in the "all" package pattern,
901 // regardless of whether we are loading the "all" package pattern.
903 // When the pkgInAll flag and pkgImportsLoaded flags are both set, the caller
904 // who set the last of those flags must propagate the pkgInAll marking to all
905 // of the imports of the marked package.
907 // A test is marked with pkgInAll if that test would promote the packages it
908 // imports to be in "all" (such as when the test is itself within the main
909 // module, or when ld.allClosesOverTests is true).
910 pkgInAll loadPkgFlags = 1 << iota
912 // pkgIsRoot indicates that the package matches one of the root package
913 // patterns requested by the caller.
915 // If LoadTests is set, then when pkgIsRoot and pkgImportsLoaded are both set,
916 // the caller who set the last of those flags must populate a test for the
917 // package (in the pkg.test field).
919 // If the "all" pattern is included as a root, then non-test packages in "all"
920 // are also roots (and must be marked pkgIsRoot).
923 // pkgFromRoot indicates that the package is in the transitive closure of
924 // imports starting at the roots. (Note that every package marked as pkgIsRoot
925 // is also trivially marked pkgFromRoot.)
928 // pkgImportsLoaded indicates that the imports and testImports fields of a
929 // loadPkg have been populated.
933 // has reports whether all of the flags in cond are set in f.
934 func (f loadPkgFlags) has(cond loadPkgFlags) bool {
935 return f&cond == cond
938 // An atomicLoadPkgFlags stores a loadPkgFlags for which individual flags can be
940 type atomicLoadPkgFlags struct {
944 // update sets the given flags in af (in addition to any flags already set).
946 // update returns the previous flag state so that the caller may determine which
947 // flags were newly-set.
948 func (af *atomicLoadPkgFlags) update(flags loadPkgFlags) (old loadPkgFlags) {
950 old := atomic.LoadInt32(&af.bits)
951 new := old | int32(flags)
952 if new == old || atomic.CompareAndSwapInt32(&af.bits, old, new) {
953 return loadPkgFlags(old)
958 // has reports whether all of the flags in cond are set in af.
959 func (af *atomicLoadPkgFlags) has(cond loadPkgFlags) bool {
960 return loadPkgFlags(atomic.LoadInt32(&af.bits))&cond == cond
963 // isTest reports whether pkg is a test of another package.
964 func (pkg *loadPkg) isTest() bool {
965 return pkg.testOf != nil
968 // fromExternalModule reports whether pkg was loaded from a module other than
970 func (pkg *loadPkg) fromExternalModule() bool {
971 if pkg.mod.Path == "" {
972 return false // loaded from the standard library, not a module
974 return !MainModules.Contains(pkg.mod.Path)
977 var errMissing = errors.New("cannot find package")
979 // loadFromRoots attempts to load the build graph needed to process a set of
980 // root packages and their dependencies.
982 // The set of root packages is returned by the params.listRoots function, and
983 // expanded to the full set of packages by tracing imports (and possibly tests)
985 func loadFromRoots(ctx context.Context, params loaderParams) *loader {
987 loaderParams: params,
988 work: par.NewQueue(runtime.GOMAXPROCS(0)),
991 if ld.GoVersion == "" {
992 ld.GoVersion = modFileGoVersion()
994 if ld.Tidy && semver.Compare("v"+ld.GoVersion, "v"+LatestGoVersion()) > 0 {
995 ld.errorf("go mod tidy: go.mod file indicates go %s, but maximum supported version is %s\n", ld.GoVersion, LatestGoVersion())
1001 if ld.TidyCompatibleVersion == "" {
1002 ld.TidyCompatibleVersion = priorGoVersion(ld.GoVersion)
1003 } else if semver.Compare("v"+ld.TidyCompatibleVersion, "v"+ld.GoVersion) > 0 {
1004 // Each version of the Go toolchain knows how to interpret go.mod and
1005 // go.sum files produced by all previous versions, so a compatibility
1006 // version higher than the go.mod version adds nothing.
1007 ld.TidyCompatibleVersion = ld.GoVersion
1011 if semver.Compare("v"+ld.GoVersion, narrowAllVersionV) < 0 && !ld.UseVendorAll {
1012 // The module's go version explicitly predates the change in "all" for lazy
1013 // loading, so continue to use the older interpretation.
1014 ld.allClosesOverTests = true
1018 ld.requirements, err = convertDepth(ctx, ld.requirements, modDepthFromGoVersion(ld.GoVersion))
1020 ld.errorf("go: %v\n", err)
1023 if ld.requirements.depth == eager {
1025 ld.requirements, _, err = expandGraph(ctx, ld.requirements)
1027 ld.errorf("go: %v\n", err)
1034 // Load the root packages and their imports.
1035 // Note: the returned roots can change on each iteration,
1036 // since the expansion of package patterns depends on the
1037 // build list we're using.
1038 rootPkgs := ld.listRoots(ld.requirements)
1040 if ld.requirements.depth == lazy && cfg.BuildMod == "mod" {
1041 // Before we start loading transitive imports of packages, locate all of
1042 // the root packages and promote their containing modules to root modules
1043 // dependencies. If their go.mod files are tidy (the common case) and the
1044 // set of root packages does not change then we can select the correct
1045 // versions of all transitive imports on the first try and complete
1046 // loading in a single iteration.
1047 changedBuildList := ld.preloadRootModules(ctx, rootPkgs)
1048 if changedBuildList {
1049 // The build list has changed, so the set of root packages may have also
1050 // changed. Start over to pick up the changes. (Preloading roots is much
1051 // cheaper than loading the full import graph, so we would rather pay
1052 // for an extra iteration of preloading than potentially end up
1053 // discarding the result of a full iteration of loading.)
1058 inRoots := map[*loadPkg]bool{}
1059 for _, path := range rootPkgs {
1060 root := ld.pkg(ctx, path, pkgIsRoot)
1062 ld.roots = append(ld.roots, root)
1063 inRoots[root] = true
1067 // ld.pkg adds imported packages to the work queue and calls applyPkgFlags,
1068 // which adds tests (and test dependencies) as needed.
1070 // When all of the work in the queue has completed, we'll know that the
1071 // transitive closure of dependencies has been loaded.
1076 changed, err := ld.updateRequirements(ctx)
1078 ld.errorf("go: %v\n", err)
1082 // Don't resolve missing imports until the module graph have stabilized.
1083 // If the roots are still changing, they may turn out to specify a
1084 // requirement on the missing package(s), and we would rather use a
1085 // version specified by a new root than add a new dependency on an
1086 // unrelated version.
1090 if !ld.ResolveMissingImports || (!HasModRoot() && !allowMissingModuleImports) {
1091 // We've loaded as much as we can without resolving missing imports.
1095 modAddedBy := ld.resolveMissingImports(ctx)
1096 if len(modAddedBy) == 0 {
1097 // The roots are stable, and we've resolved all of the missing packages
1102 toAdd := make([]module.Version, 0, len(modAddedBy))
1103 for m, _ := range modAddedBy {
1104 toAdd = append(toAdd, m)
1106 module.Sort(toAdd) // to make errors deterministic
1108 // We ran updateRequirements before resolving missing imports and it didn't
1109 // make any changes, so we know that the requirement graph is already
1110 // consistent with ld.pkgs: we don't need to pass ld.pkgs to updateRoots
1111 // again. (That would waste time looking for changes that we have already
1113 var noPkgs []*loadPkg
1114 // We also know that we're going to call updateRequirements again next
1115 // iteration so we don't need to also update it here. (That would waste time
1116 // computing a "direct" map that we'll have to recompute later anyway.)
1117 direct := ld.requirements.direct
1118 rs, err := updateRoots(ctx, direct, ld.requirements, noPkgs, toAdd, ld.AssumeRootsImported)
1120 // If an error was found in a newly added module, report the package
1121 // import stack instead of the module requirement stack. Packages
1122 // are more descriptive.
1123 if err, ok := err.(*mvs.BuildListError); ok {
1124 if pkg := modAddedBy[err.Module()]; pkg != nil {
1125 ld.errorf("go: %s: %v\n", pkg.stackText(), err.Err)
1129 ld.errorf("go: %v\n", err)
1132 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1133 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1134 // set of modules to add to the graph, but adding those modules had no
1135 // effect — either they were already in the graph, or updateRoots did not
1136 // add them as requested.
1137 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1139 ld.requirements = rs
1141 base.ExitIfErrors() // TODO(bcmills): Is this actually needed?
1143 // Tidy the build list, if applicable, before we report errors.
1144 // (The process of tidying may remove errors from irrelevant dependencies.)
1146 rs, err := tidyRoots(ctx, ld.requirements, ld.pkgs)
1148 ld.errorf("go: %v\n", err)
1151 if ld.requirements.depth == lazy {
1152 // We continuously add tidy roots to ld.requirements during loading, so at
1153 // this point the tidy roots should be a subset of the roots of
1154 // ld.requirements, ensuring that no new dependencies are brought inside
1155 // the lazy-loading horizon.
1156 // If that is not the case, there is a bug in the loading loop above.
1157 for _, m := range rs.rootModules {
1158 if v, ok := ld.requirements.rootSelected(m.Path); !ok || v != m.Version {
1159 ld.errorf("go mod tidy: internal error: a requirement on %v is needed but was not added during package loading\n", m)
1164 ld.requirements = rs
1167 // Report errors, if any.
1168 for _, pkg := range ld.pkgs {
1173 // Add importer information to checksum errors.
1174 if sumErr := (*ImportMissingSumError)(nil); errors.As(pkg.err, &sumErr) {
1175 if importer := pkg.stack; importer != nil {
1176 sumErr.importer = importer.path
1177 sumErr.importerVersion = importer.mod.Version
1178 sumErr.importerIsTest = importer.testOf != nil
1182 if ld.SilencePackageErrors {
1185 if stdErr := (*ImportMissingError)(nil); errors.As(pkg.err, &stdErr) &&
1186 stdErr.isStd && ld.SilenceMissingStdImports {
1189 if ld.SilenceNoGoErrors && errors.Is(pkg.err, imports.ErrNoGo) {
1193 ld.errorf("%s: %v\n", pkg.stackText(), pkg.err)
1196 ld.checkMultiplePaths()
1200 // updateRequirements ensures that ld.requirements is consistent with the
1201 // information gained from ld.pkgs and includes the modules in add as roots at
1202 // at least the given versions.
1206 // - Modules that provide packages directly imported from the main module are
1207 // marked as direct, and are promoted to explicit roots. If a needed root
1208 // cannot be promoted due to -mod=readonly or -mod=vendor, the importing
1209 // package is marked with an error.
1211 // - If ld scanned the "all" pattern independent of build constraints, it is
1212 // guaranteed to have seen every direct import. Module dependencies that did
1213 // not provide any directly-imported package are then marked as indirect.
1215 // - Root dependencies are updated to their selected versions.
1217 // The "changed" return value reports whether the update changed the selected
1218 // version of any module that either provided a loaded package or may now
1219 // provide a package that was previously unresolved.
1220 func (ld *loader) updateRequirements(ctx context.Context) (changed bool, err error) {
1221 rs := ld.requirements
1223 // direct contains the set of modules believed to provide packages directly
1224 // imported by the main module.
1225 var direct map[string]bool
1227 // If we didn't scan all of the imports from the main module, or didn't use
1228 // imports.AnyTags, then we didn't necessarily load every package that
1229 // contributes “direct” imports — so we can't safely mark existing direct
1230 // dependencies in ld.requirements as indirect-only. Propagate them as direct.
1231 loadedDirect := ld.allPatternIsRoot && reflect.DeepEqual(ld.Tags, imports.AnyTags())
1233 direct = make(map[string]bool)
1235 // TODO(bcmills): It seems like a shame to allocate and copy a map here when
1236 // it will only rarely actually vary from rs.direct. Measure this cost and
1237 // maybe avoid the copy.
1238 direct = make(map[string]bool, len(rs.direct))
1239 for mPath := range rs.direct {
1240 direct[mPath] = true
1244 for _, pkg := range ld.pkgs {
1245 if pkg.mod.Version != "" || !MainModules.Contains(pkg.mod.Path) {
1248 for _, dep := range pkg.imports {
1249 if !dep.fromExternalModule() {
1253 if pkg.err == nil && cfg.BuildMod != "mod" {
1254 if v, ok := rs.rootSelected(dep.mod.Path); !ok || v != dep.mod.Version {
1255 // dep.mod is not an explicit dependency, but needs to be.
1256 // Because we are not in "mod" mode, we will not be able to update it.
1257 // Instead, mark the importing package with an error.
1259 // TODO(#41688): The resulting error message fails to include the file
1260 // position of the import statement (because that information is not
1261 // tracked by the module loader). Figure out how to plumb the import
1262 // position through.
1263 pkg.err = &DirectImportFromImplicitDependencyError{
1264 ImporterPath: pkg.path,
1265 ImportedPath: dep.path,
1268 // cfg.BuildMod does not allow us to change dep.mod to be a direct
1269 // dependency, so don't mark it as such.
1274 // dep is a package directly imported by a package or test in the main
1275 // module and loaded from some other module (not the standard library).
1276 // Mark its module as a direct dependency.
1277 direct[dep.mod.Path] = true
1281 var addRoots []module.Version
1283 // When we are tidying a lazy module, we may need to add roots to preserve
1284 // the versions of indirect, test-only dependencies that are upgraded
1285 // above or otherwise missing from the go.mod files of direct
1286 // dependencies. (For example, the direct dependency might be a very
1287 // stable codebase that predates modules and thus lacks a go.mod file, or
1288 // the author of the direct dependency may have forgotten to commit a
1289 // change to the go.mod file, or may have made an erroneous hand-edit that
1290 // causes it to be untidy.)
1292 // Promoting an indirect dependency to a root adds the next layer of its
1293 // dependencies to the module graph, which may increase the selected
1294 // versions of other modules from which we have already loaded packages.
1295 // So after we promote an indirect dependency to a root, we need to reload
1296 // packages, which means another iteration of loading.
1298 // As an extra wrinkle, the upgrades due to promoting a root can cause
1299 // previously-resolved packages to become unresolved. For example, the
1300 // module providing an unstable package might be upgraded to a version
1301 // that no longer contains that package. If we then resolve the missing
1302 // package, we might add yet another root that upgrades away some other
1303 // dependency. (The tests in mod_tidy_convergence*.txt illustrate some
1304 // particularly worrisome cases.)
1306 // To ensure that this process of promoting, adding, and upgrading roots
1307 // eventually terminates, during iteration we only ever add modules to the
1308 // root set — we only remove irrelevant roots at the very end of
1309 // iteration, after we have already added every root that we plan to need
1310 // in the (eventual) tidy root set.
1312 // Since we do not remove any roots during iteration, even if they no
1313 // longer provide any imported packages, the selected versions of the
1314 // roots can only increase and the set of roots can only expand. The set
1315 // of extant root paths is finite and the set of versions of each path is
1316 // finite, so the iteration *must* reach a stable fixed-point.
1317 tidy, err := tidyRoots(ctx, rs, ld.pkgs)
1321 addRoots = tidy.rootModules
1324 rs, err = updateRoots(ctx, direct, rs, ld.pkgs, addRoots, ld.AssumeRootsImported)
1326 // We don't actually know what even the root requirements are supposed to be,
1327 // so we can't proceed with loading. Return the error to the caller
1331 if rs != ld.requirements && !reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1332 // The roots of the module graph have changed in some way (not just the
1333 // "direct" markings). Check whether the changes affected any of the loaded
1335 mg, err := rs.Graph(ctx)
1339 for _, pkg := range ld.pkgs {
1340 if pkg.fromExternalModule() && mg.Selected(pkg.mod.Path) != pkg.mod.Version {
1345 // Promoting a module to a root may resolve an import that was
1346 // previously missing (by pulling in a previously-prune dependency that
1347 // provides it) or ambiguous (by promoting exactly one of the
1348 // alternatives to a root and ignoring the second-level alternatives) or
1349 // otherwise errored out (by upgrading from a version that cannot be
1350 // fetched to one that can be).
1352 // Instead of enumerating all of the possible errors, we'll just check
1353 // whether importFromModules returns nil for the package.
1354 // False-positives are ok: if we have a false-positive here, we'll do an
1355 // extra iteration of package loading this time, but we'll still
1356 // converge when the root set stops changing.
1358 // In some sense, we can think of this as ‘upgraded the module providing
1359 // pkg.path from "none" to a version higher than "none"’.
1360 if _, _, err = importFromModules(ctx, pkg.path, rs, nil); err == nil {
1368 ld.requirements = rs
1372 // resolveMissingImports returns a set of modules that could be added as
1373 // dependencies in order to resolve missing packages from pkgs.
1375 // The newly-resolved packages are added to the addedModuleFor map, and
1376 // resolveMissingImports returns a map from each new module version to
1377 // the first missing package that module would resolve.
1378 func (ld *loader) resolveMissingImports(ctx context.Context) (modAddedBy map[module.Version]*loadPkg) {
1379 type pkgMod struct {
1383 var pkgMods []pkgMod
1384 for _, pkg := range ld.pkgs {
1389 // If we are missing a test, we are also missing its non-test version, and
1390 // we should only add the missing import once.
1393 if !errors.As(pkg.err, new(*ImportMissingError)) {
1394 // Leave other errors for Import or load.Packages to report.
1399 var mod module.Version
1400 ld.work.Add(func() {
1402 mod, err = queryImport(ctx, pkg.path, ld.requirements)
1404 // pkg.err was already non-nil, so we can reasonably attribute the error
1405 // for pkg to either the original error or the one returned by
1406 // queryImport. The existing error indicates only that we couldn't find
1407 // the package, whereas the query error also explains why we didn't fix
1408 // the problem — so we prefer the latter.
1412 // err is nil, but we intentionally leave pkg.err non-nil and pkg.mod
1413 // unset: we still haven't satisfied other invariants of a
1414 // successfully-loaded package, such as scanning and loading the imports
1415 // of that package. If we succeed in resolving the new dependency graph,
1416 // the caller can reload pkg and update the error at that point.
1418 // Even then, the package might not be loaded from the version we've
1419 // identified here. The module may be upgraded by some other dependency,
1420 // or by a transitive dependency of mod itself, or — less likely — the
1421 // package may be rejected by an AllowPackage hook or rendered ambiguous
1422 // by some other newly-added or newly-upgraded dependency.
1425 pkgMods = append(pkgMods, pkgMod{pkg: pkg, mod: &mod})
1429 modAddedBy = map[module.Version]*loadPkg{}
1430 for _, pm := range pkgMods {
1431 pkg, mod := pm.pkg, *pm.mod
1436 fmt.Fprintf(os.Stderr, "go: found %s in %s %s\n", pkg.path, mod.Path, mod.Version)
1437 if modAddedBy[mod] == nil {
1438 modAddedBy[mod] = pkg
1445 // pkg locates the *loadPkg for path, creating and queuing it for loading if
1446 // needed, and updates its state to reflect the given flags.
1448 // The imports of the returned *loadPkg will be loaded asynchronously in the
1449 // ld.work queue, and its test (if requested) will also be populated once
1450 // imports have been resolved. When ld.work goes idle, all transitive imports of
1451 // the requested package (and its test, if requested) will have been loaded.
1452 func (ld *loader) pkg(ctx context.Context, path string, flags loadPkgFlags) *loadPkg {
1453 if flags.has(pkgImportsLoaded) {
1454 panic("internal error: (*loader).pkg called with pkgImportsLoaded flag set")
1457 pkg := ld.pkgCache.Do(path, func() interface{} {
1461 ld.applyPkgFlags(ctx, pkg, flags)
1463 ld.work.Add(func() { ld.load(ctx, pkg) })
1467 ld.applyPkgFlags(ctx, pkg, flags)
1471 // applyPkgFlags updates pkg.flags to set the given flags and propagate the
1472 // (transitive) effects of those flags, possibly loading or enqueueing further
1473 // packages as a result.
1474 func (ld *loader) applyPkgFlags(ctx context.Context, pkg *loadPkg, flags loadPkgFlags) {
1479 if flags.has(pkgInAll) && ld.allPatternIsRoot && !pkg.isTest() {
1480 // This package matches a root pattern by virtue of being in "all".
1483 if flags.has(pkgIsRoot) {
1484 flags |= pkgFromRoot
1487 old := pkg.flags.update(flags)
1489 if new == old || !new.has(pkgImportsLoaded) {
1490 // We either didn't change the state of pkg, or we don't know anything about
1491 // its dependencies yet. Either way, we can't usefully load its test or
1492 // update its dependencies.
1497 // Check whether we should add (or update the flags for) a test for pkg.
1498 // ld.pkgTest is idempotent and extra invocations are inexpensive,
1499 // so it's ok if we call it more than is strictly necessary.
1502 case ld.allPatternIsRoot && MainModules.Contains(pkg.mod.Path):
1503 // We are loading the "all" pattern, which includes packages imported by
1504 // tests in the main module. This package is in the main module, so we
1505 // need to identify the imports of its test even if LoadTests is not set.
1507 // (We will filter out the extra tests explicitly in computePatternAll.)
1510 case ld.allPatternIsRoot && ld.allClosesOverTests && new.has(pkgInAll):
1511 // This variant of the "all" pattern includes imports of tests of every
1512 // package that is itself in "all", and pkg is in "all", so its test is
1513 // also in "all" (as above).
1516 case ld.LoadTests && new.has(pkgIsRoot):
1517 // LoadTest explicitly requests tests of “the root packages”.
1522 var testFlags loadPkgFlags
1523 if MainModules.Contains(pkg.mod.Path) || (ld.allClosesOverTests && new.has(pkgInAll)) {
1524 // Tests of packages in the main module are in "all", in the sense that
1525 // they cause the packages they import to also be in "all". So are tests
1526 // of packages in "all" if "all" closes over test dependencies.
1527 testFlags |= pkgInAll
1529 ld.pkgTest(ctx, pkg, testFlags)
1533 if new.has(pkgInAll) && !old.has(pkgInAll|pkgImportsLoaded) {
1534 // We have just marked pkg with pkgInAll, or we have just loaded its
1535 // imports, or both. Now is the time to propagate pkgInAll to the imports.
1536 for _, dep := range pkg.imports {
1537 ld.applyPkgFlags(ctx, dep, pkgInAll)
1541 if new.has(pkgFromRoot) && !old.has(pkgFromRoot|pkgImportsLoaded) {
1542 for _, dep := range pkg.imports {
1543 ld.applyPkgFlags(ctx, dep, pkgFromRoot)
1548 // preloadRootModules loads the module requirements needed to identify the
1549 // selected version of each module providing a package in rootPkgs,
1550 // adding new root modules to the module graph if needed.
1551 func (ld *loader) preloadRootModules(ctx context.Context, rootPkgs []string) (changedBuildList bool) {
1552 needc := make(chan map[module.Version]bool, 1)
1553 needc <- map[module.Version]bool{}
1554 for _, path := range rootPkgs {
1556 ld.work.Add(func() {
1557 // First, try to identify the module containing the package using only roots.
1559 // If the main module is tidy and the package is in "all" — or if we're
1560 // lucky — we can identify all of its imports without actually loading the
1561 // full module graph.
1562 m, _, err := importFromModules(ctx, path, ld.requirements, nil)
1564 var missing *ImportMissingError
1565 if errors.As(err, &missing) && ld.ResolveMissingImports {
1566 // This package isn't provided by any selected module.
1567 // If we can find it, it will be a new root dependency.
1568 m, err = queryImport(ctx, path, ld.requirements)
1571 // We couldn't identify the root module containing this package.
1572 // Leave it unresolved; we will report it during loading.
1577 // The package is in std or cmd. We don't need to change the root set.
1581 v, ok := ld.requirements.rootSelected(m.Path)
1582 if !ok || v != m.Version {
1583 // We found the requested package in m, but m is not a root, so
1584 // loadModGraph will not load its requirements. We need to promote the
1585 // module to a root to ensure that any other packages this package
1586 // imports are resolved from correct dependency versions.
1588 // (This is the “argument invariant” from the lazy loading design.)
1599 return false // No roots to add.
1602 toAdd := make([]module.Version, 0, len(need))
1603 for m := range need {
1604 toAdd = append(toAdd, m)
1608 rs, err := updateRoots(ctx, ld.requirements.direct, ld.requirements, nil, toAdd, ld.AssumeRootsImported)
1610 // We are missing some root dependency, and for some reason we can't load
1611 // enough of the module dependency graph to add the missing root. Package
1612 // loading is doomed to fail, so fail quickly.
1613 ld.errorf("go: %v\n", err)
1617 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1618 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1619 // set of modules to add to the graph, but adding those modules had no
1620 // effect — either they were already in the graph, or updateRoots did not
1621 // add them as requested.
1622 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1625 ld.requirements = rs
1629 // load loads an individual package.
1630 func (ld *loader) load(ctx context.Context, pkg *loadPkg) {
1631 if strings.Contains(pkg.path, "@") {
1632 // Leave for error during load.
1635 if build.IsLocalImport(pkg.path) || filepath.IsAbs(pkg.path) {
1636 // Leave for error during load.
1637 // (Module mode does not allow local imports.)
1641 if search.IsMetaPackage(pkg.path) {
1642 pkg.err = &invalidImportError{
1643 importPath: pkg.path,
1644 err: fmt.Errorf("%q is not an importable package; see 'go help packages'", pkg.path),
1650 if ld.requirements.depth == eager {
1652 mg, err = ld.requirements.Graph(ctx)
1654 // We already checked the error from Graph in loadFromRoots and/or
1655 // updateRequirements, so we ignored the error on purpose and we should
1656 // keep trying to push past it.
1658 // However, because mg may be incomplete (and thus may select inaccurate
1659 // versions), we shouldn't use it to load packages. Instead, we pass a nil
1660 // *ModuleGraph, which will cause mg to first try loading from only the
1661 // main module and root dependencies.
1666 pkg.mod, pkg.dir, pkg.err = importFromModules(ctx, pkg.path, ld.requirements, mg)
1670 if MainModules.Contains(pkg.mod.Path) {
1671 // Go ahead and mark pkg as in "all". This provides the invariant that a
1672 // package that is *only* imported by other packages in "all" is always
1673 // marked as such before loading its imports.
1675 // We don't actually rely on that invariant at the moment, but it may
1676 // improve efficiency somewhat and makes the behavior a bit easier to reason
1677 // about (by reducing churn on the flag bits of dependencies), and costs
1678 // essentially nothing (these atomic flag ops are essentially free compared
1679 // to scanning source code for imports).
1680 ld.applyPkgFlags(ctx, pkg, pkgInAll)
1682 if ld.AllowPackage != nil {
1683 if err := ld.AllowPackage(ctx, pkg.path, pkg.mod); err != nil {
1688 pkg.inStd = (search.IsStandardImportPath(pkg.path) && search.InDir(pkg.dir, cfg.GOROOTsrc) != "")
1690 var imports, testImports []string
1692 if cfg.BuildContext.Compiler == "gccgo" && pkg.inStd {
1693 // We can't scan standard packages for gccgo.
1696 imports, testImports, err = scanDir(pkg.dir, ld.Tags)
1703 pkg.imports = make([]*loadPkg, 0, len(imports))
1704 var importFlags loadPkgFlags
1705 if pkg.flags.has(pkgInAll) {
1706 importFlags = pkgInAll
1708 for _, path := range imports {
1710 // Imports from packages in "std" and "cmd" should resolve using
1711 // GOROOT/src/vendor even when "std" is not the main module.
1712 path = ld.stdVendor(pkg.path, path)
1714 pkg.imports = append(pkg.imports, ld.pkg(ctx, path, importFlags))
1716 pkg.testImports = testImports
1718 ld.applyPkgFlags(ctx, pkg, pkgImportsLoaded)
1721 // pkgTest locates the test of pkg, creating it if needed, and updates its state
1722 // to reflect the given flags.
1724 // pkgTest requires that the imports of pkg have already been loaded (flagged
1725 // with pkgImportsLoaded).
1726 func (ld *loader) pkgTest(ctx context.Context, pkg *loadPkg, testFlags loadPkgFlags) *loadPkg {
1728 panic("pkgTest called on a test package")
1731 createdTest := false
1732 pkg.testOnce.Do(func() {
1733 pkg.test = &loadPkg{
1741 ld.applyPkgFlags(ctx, pkg.test, testFlags)
1747 test.imports = make([]*loadPkg, 0, len(pkg.testImports))
1748 var importFlags loadPkgFlags
1749 if test.flags.has(pkgInAll) {
1750 importFlags = pkgInAll
1752 for _, path := range pkg.testImports {
1754 path = ld.stdVendor(test.path, path)
1756 test.imports = append(test.imports, ld.pkg(ctx, path, importFlags))
1758 pkg.testImports = nil
1759 ld.applyPkgFlags(ctx, test, pkgImportsLoaded)
1761 ld.applyPkgFlags(ctx, test, testFlags)
1767 // stdVendor returns the canonical import path for the package with the given
1768 // path when imported from the standard-library package at parentPath.
1769 func (ld *loader) stdVendor(parentPath, path string) string {
1770 if search.IsStandardImportPath(path) {
1774 if str.HasPathPrefix(parentPath, "cmd") {
1775 if !ld.VendorModulesInGOROOTSrc || !MainModules.Contains("cmd") {
1776 vendorPath := pathpkg.Join("cmd", "vendor", path)
1778 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1782 } else if !ld.VendorModulesInGOROOTSrc || !MainModules.Contains("std") || str.HasPathPrefix(parentPath, "vendor") {
1783 // If we are outside of the 'std' module, resolve imports from within 'std'
1784 // to the vendor directory.
1786 // Do the same for importers beginning with the prefix 'vendor/' even if we
1787 // are *inside* of the 'std' module: the 'vendor/' packages that resolve
1788 // globally from GOROOT/src/vendor (and are listed as part of 'go list std')
1789 // are distinct from the real module dependencies, and cannot import
1790 // internal packages from the real module.
1792 // (Note that although the 'vendor/' packages match the 'std' *package*
1793 // pattern, they are not part of the std *module*, and do not affect
1794 // 'go mod tidy' and similar module commands when working within std.)
1795 vendorPath := pathpkg.Join("vendor", path)
1796 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1801 // Not vendored: resolve from modules.
1805 // computePatternAll returns the list of packages matching pattern "all",
1806 // starting with a list of the import paths for the packages in the main module.
1807 func (ld *loader) computePatternAll() (all []string) {
1808 for _, pkg := range ld.pkgs {
1809 if pkg.flags.has(pkgInAll) && !pkg.isTest() {
1810 all = append(all, pkg.path)
1817 // checkMultiplePaths verifies that a given module path is used as itself
1818 // or as a replacement for another module, but not both at the same time.
1820 // (See https://golang.org/issue/26607 and https://golang.org/issue/34650.)
1821 func (ld *loader) checkMultiplePaths() {
1822 mods := ld.requirements.rootModules
1823 if cached := ld.requirements.graph.Load(); cached != nil {
1824 if mg := cached.(cachedGraph).mg; mg != nil {
1825 mods = mg.BuildList()
1829 firstPath := map[module.Version]string{}
1830 for _, mod := range mods {
1831 src := resolveReplacement(mod)
1832 if prev, ok := firstPath[src]; !ok {
1833 firstPath[src] = mod.Path
1834 } else if prev != mod.Path {
1835 ld.errorf("go: %s@%s used for two different module paths (%s and %s)\n", src.Path, src.Version, prev, mod.Path)
1840 // checkTidyCompatibility emits an error if any package would be loaded from a
1841 // different module under rs than under ld.requirements.
1842 func (ld *loader) checkTidyCompatibility(ctx context.Context, rs *Requirements) {
1843 suggestUpgrade := false
1844 suggestEFlag := false
1845 suggestFixes := func() {
1847 // The user is explicitly ignoring these errors, so don't bother them with
1852 // We print directly to os.Stderr because this information is advice about
1853 // how to fix errors, not actually an error itself.
1854 // (The actual errors should have been logged already.)
1856 fmt.Fprintln(os.Stderr)
1859 if ld.GoVersion != modFileGoVersion() {
1860 goFlag = " -go=" + ld.GoVersion
1864 if ld.TidyCompatibleVersion != priorGoVersion(ld.GoVersion) {
1865 compatFlag = " -compat=" + ld.TidyCompatibleVersion
1871 eDesc = ", leaving some packages unresolved"
1874 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)
1875 } else if suggestEFlag {
1876 // If some packages are missing but no package is upgraded, then we
1877 // shouldn't suggest upgrading to the Go 1.16 versions explicitly — that
1878 // wouldn't actually fix anything for Go 1.16 users, and *would* break
1879 // something for Go 1.17 users.
1880 fmt.Fprintf(os.Stderr, "To proceed despite packages unresolved in go %s:\n\tgo mod tidy -e%s%s\n", ld.TidyCompatibleVersion, goFlag, compatFlag)
1883 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)
1885 // TODO(#46141): Populate the linked wiki page.
1886 fmt.Fprintf(os.Stderr, "For other options, see:\n\thttps://golang.org/wiki/PruningModules\n")
1889 mg, err := rs.Graph(ctx)
1891 ld.errorf("go mod tidy: error loading go %s module graph: %v\n", ld.TidyCompatibleVersion, err)
1896 // Re-resolve packages in parallel.
1898 // We re-resolve each package — rather than just checking versions — to ensure
1899 // that we have fetched module source code (and, importantly, checksums for
1900 // that source code) for all modules that are necessary to ensure that imports
1901 // are unambiguous. That also produces clearer diagnostics, since we can say
1902 // exactly what happened to the package if it became ambiguous or disappeared
1905 // We re-resolve the packages in parallel because this process involves disk
1906 // I/O to check for package sources, and because the process of checking for
1907 // ambiguous imports may require us to download additional modules that are
1908 // otherwise pruned out in Go 1.17 — we don't want to block progress on other
1909 // packages while we wait for a single new download.
1910 type mismatch struct {
1914 mismatchMu := make(chan map[*loadPkg]mismatch, 1)
1915 mismatchMu <- map[*loadPkg]mismatch{}
1916 for _, pkg := range ld.pkgs {
1917 if pkg.mod.Path == "" && pkg.err == nil {
1918 // This package is from the standard library (which does not vary based on
1919 // the module graph).
1924 ld.work.Add(func() {
1925 mod, _, err := importFromModules(ctx, pkg.path, rs, mg)
1927 mismatches := <-mismatchMu
1928 mismatches[pkg] = mismatch{mod: mod, err: err}
1929 mismatchMu <- mismatches
1935 mismatches := <-mismatchMu
1936 if len(mismatches) == 0 {
1937 // Since we're running as part of 'go mod tidy', the roots of the module
1938 // graph should contain only modules that are relevant to some package in
1939 // the package graph. We checked every package in the package graph and
1940 // didn't find any mismatches, so that must mean that all of the roots of
1941 // the module graph are also consistent.
1943 // If we're wrong, Go 1.16 in -mod=readonly mode will error out with
1944 // "updates to go.mod needed", which would be very confusing. So instead,
1945 // we'll double-check that our reasoning above actually holds — if it
1946 // doesn't, we'll emit an internal error and hopefully the user will report
1948 for _, m := range ld.requirements.rootModules {
1949 if v := mg.Selected(m.Path); v != m.Version {
1950 fmt.Fprintln(os.Stderr)
1951 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)
1957 // Iterate over the packages (instead of the mismatches map) to emit errors in
1958 // deterministic order.
1959 for _, pkg := range ld.pkgs {
1960 mismatch, ok := mismatches[pkg]
1966 // We already did (or will) report an error for the package itself,
1967 // so don't report a duplicate (and more vebose) error for its test.
1968 if _, ok := mismatches[pkg.testOf]; !ok {
1969 base.Fatalf("go: internal error: mismatch recorded for test %s, but not its non-test package", pkg.path)
1975 case mismatch.err != nil:
1976 // pkg resolved successfully, but errors out using the requirements in rs.
1978 // This could occur because the import is provided by a single lazy root
1979 // (and is thus unambiguous in lazy mode) and also one or more
1980 // transitive dependencies (and is ambiguous in eager mode).
1982 // It could also occur because some transitive dependency upgrades the
1983 // module that previously provided the package to a version that no
1984 // longer does, or to a version for which the module source code (but
1985 // not the go.mod file in isolation) has a checksum error.
1986 if missing := (*ImportMissingError)(nil); errors.As(mismatch.err, &missing) {
1987 selected := module.Version{
1989 Version: mg.Selected(pkg.mod.Path),
1991 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)
1993 if ambiguous := (*AmbiguousImportError)(nil); errors.As(mismatch.err, &ambiguous) {
1994 // TODO: Is this check needed?
1996 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)
2001 // Even if we press ahead with the '-e' flag, the older version will
2002 // error out in readonly mode if it thinks the go.mod file contains
2003 // any *explicit* dependency that is not at its selected version,
2004 // even if that dependency is not relevant to any package being loaded.
2006 // We check for that condition here. If all of the roots are consistent
2007 // the '-e' flag suffices, but otherwise we need to suggest an upgrade.
2008 if !suggestUpgrade {
2009 for _, m := range ld.requirements.rootModules {
2010 if v := mg.Selected(m.Path); v != m.Version {
2011 suggestUpgrade = true
2017 case pkg.err != nil:
2018 // pkg had an error in lazy mode (presumably suppressed with the -e flag),
2019 // but not in eager mode.
2021 // This is possible, if, say, the import is unresolved in lazy mode
2022 // (because the "latest" version of each candidate module either is
2023 // unavailable or does not contain the package), but is resolved in
2024 // eager mode due to a newer-than-latest dependency that is normally
2025 // runed out of the module graph.
2027 // This could also occur if the source code for the module providing the
2028 // package in lazy mode has a checksum error, but eager mode upgrades
2029 // that module to a version with a correct checksum.
2031 // pkg.err should have already been logged elsewhere — along with a
2032 // stack trace — so log only the import path and non-error info here.
2033 suggestUpgrade = true
2034 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)
2036 case pkg.mod != mismatch.mod:
2037 // The package is loaded successfully by both Go versions, but from a
2038 // different module in each. This could lead to subtle (and perhaps even
2039 // unnoticed!) variations in behavior between builds with different
2041 suggestUpgrade = true
2042 ld.errorf("%s loaded from %v,\n\tbut go %s would select %v\n", pkg.stackText(), pkg.mod, ld.TidyCompatibleVersion, mismatch.mod.Version)
2045 base.Fatalf("go: internal error: mismatch recorded for package %s, but no differences found", pkg.path)
2053 // scanDir is like imports.ScanDir but elides known magic imports from the list,
2054 // so that we do not go looking for packages that don't really exist.
2056 // The standard magic import is "C", for cgo.
2058 // The only other known magic imports are appengine and appengine/*.
2059 // These are so old that they predate "go get" and did not use URL-like paths.
2060 // Most code today now uses google.golang.org/appengine instead,
2061 // but not all code has been so updated. When we mostly ignore build tags
2062 // during "go vendor", we look into "// +build appengine" files and
2063 // may see these legacy imports. We drop them so that the module
2064 // search does not look for modules to try to satisfy them.
2065 func scanDir(dir string, tags map[string]bool) (imports_, testImports []string, err error) {
2066 imports_, testImports, err = imports.ScanDir(dir, tags)
2068 filter := func(x []string) []string {
2070 for _, pkg := range x {
2071 if pkg != "C" && pkg != "appengine" && !strings.HasPrefix(pkg, "appengine/") &&
2072 pkg != "appengine_internal" && !strings.HasPrefix(pkg, "appengine_internal/") {
2080 return filter(imports_), filter(testImports), err
2083 // buildStacks computes minimal import stacks for each package,
2084 // for use in error messages. When it completes, packages that
2085 // are part of the original root set have pkg.stack == nil,
2086 // and other packages have pkg.stack pointing at the next
2087 // package up the import stack in their minimal chain.
2088 // As a side effect, buildStacks also constructs ld.pkgs,
2089 // the list of all packages loaded.
2090 func (ld *loader) buildStacks() {
2091 if len(ld.pkgs) > 0 {
2092 panic("buildStacks")
2094 for _, pkg := range ld.roots {
2095 pkg.stack = pkg // sentinel to avoid processing in next loop
2096 ld.pkgs = append(ld.pkgs, pkg)
2098 for i := 0; i < len(ld.pkgs); i++ { // not range: appending to ld.pkgs in loop
2100 for _, next := range pkg.imports {
2101 if next.stack == nil {
2103 ld.pkgs = append(ld.pkgs, next)
2106 if next := pkg.test; next != nil && next.stack == nil {
2108 ld.pkgs = append(ld.pkgs, next)
2111 for _, pkg := range ld.roots {
2116 // stackText builds the import stack text to use when
2117 // reporting an error in pkg. It has the general form
2122 // other2.test imports
2125 func (pkg *loadPkg) stackText() string {
2126 var stack []*loadPkg
2127 for p := pkg; p != nil; p = p.stack {
2128 stack = append(stack, p)
2131 var buf bytes.Buffer
2132 for i := len(stack) - 1; i >= 0; i-- {
2134 fmt.Fprint(&buf, p.path)
2135 if p.testOf != nil {
2136 fmt.Fprint(&buf, ".test")
2139 if stack[i-1].testOf == p {
2140 fmt.Fprint(&buf, " tested by\n\t")
2142 fmt.Fprint(&buf, " imports\n\t")
2149 // why returns the text to use in "go mod why" output about the given package.
2150 // It is less ornate than the stackText but contains the same information.
2151 func (pkg *loadPkg) why() string {
2152 var buf strings.Builder
2153 var stack []*loadPkg
2154 for p := pkg; p != nil; p = p.stack {
2155 stack = append(stack, p)
2158 for i := len(stack) - 1; i >= 0; i-- {
2160 if p.testOf != nil {
2161 fmt.Fprintf(&buf, "%s.test\n", p.testOf.path)
2163 fmt.Fprintf(&buf, "%s\n", p.path)
2169 // Why returns the "go mod why" output stanza for the given package,
2170 // without the leading # comment.
2171 // The package graph must have been loaded already, usually by LoadPackages.
2172 // If there is no reason for the package to be in the current build,
2173 // Why returns an empty string.
2174 func Why(path string) string {
2175 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
2182 // WhyDepth returns the number of steps in the Why listing.
2183 // If there is no reason for the package to be in the current build,
2184 // WhyDepth returns 0.
2185 func WhyDepth(path string) int {
2187 pkg, _ := loaded.pkgCache.Get(path).(*loadPkg)
2188 for p := pkg; p != nil; p = p.stack {