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
284 m.Pkgs = append(m.Pkgs, pkg)
288 m.Pkgs = []string{m.Pattern()}
290 case strings.Contains(m.Pattern(), "..."):
292 mg, err := rs.Graph(ctx)
294 // The module graph is (or may be) incomplete — perhaps we failed to
295 // load the requirements of some module. This is an error in matching
296 // the patterns to packages, because we may be missing some packages
297 // or we may erroneously match packages in the wrong versions of
298 // modules. However, for cases like 'go list -e', the error should not
299 // necessarily prevent us from loading the packages we could find.
300 m.Errs = append(m.Errs, err)
302 matchPackages(ctx, m, opts.Tags, includeStd, mg.BuildList())
304 case m.Pattern() == "all":
306 // The initial roots are the packages in the main module.
307 // loadFromRoots will expand that to "all".
309 matchPackages(ctx, m, opts.Tags, omitStd, []module.Version{Target})
311 // Starting with the packages in the main module,
312 // enumerate the full list of "all".
313 m.Pkgs = ld.computePatternAll()
316 case m.Pattern() == "std" || m.Pattern() == "cmd":
318 m.MatchPackages() // Locate the packages within GOROOT/src.
322 panic(fmt.Sprintf("internal error: modload missing case for pattern %s", m.Pattern()))
327 initialRS, _ := loadModFile(ctx) // Ignore needCommit — we're going to commit at the end regardless.
329 ld := loadFromRoots(ctx, loaderParams{
331 requirements: initialRS,
333 allPatternIsRoot: allPatternIsRoot,
335 listRoots: func(rs *Requirements) (roots []string) {
336 updateMatches(rs, nil)
337 for _, m := range matches {
338 roots = append(roots, m.Pkgs...)
344 // One last pass to finalize wildcards.
345 updateMatches(ld.requirements, ld)
347 // List errors in matching patterns (such as directory permission
348 // errors for wildcard patterns).
349 if !ld.SilencePackageErrors {
350 for _, match := range matches {
351 for _, err := range match.Errs {
352 ld.errorf("%v\n", err)
358 if !opts.SilenceUnmatchedWarnings {
359 search.WarnUnmatched(matches)
364 mg, _ := ld.requirements.Graph(ctx)
366 for _, m := range initialRS.rootModules {
368 if ld.requirements.depth == eager {
369 // m is unused if it was dropped from the module graph entirely. If it
370 // was only demoted from direct to indirect, it may still be in use via
371 // a transitive import.
372 unused = mg.Selected(m.Path) == "none"
374 // m is unused if it was dropped from the roots. If it is still present
375 // as a transitive dependency, that transitive dependency is not needed
376 // by any package or test in the main module.
377 _, ok := ld.requirements.rootSelected(m.Path)
381 fmt.Fprintf(os.Stderr, "unused %s\n", m.Path)
386 keep := keepSums(ctx, ld, ld.requirements, loadedZipSumsOnly)
387 if compatDepth := modDepthFromGoVersion(ld.TidyCompatibleVersion); compatDepth != ld.requirements.depth {
388 compatRS := newRequirements(compatDepth, ld.requirements.rootModules, ld.requirements.direct)
389 ld.checkTidyCompatibility(ctx, compatRS)
391 for m := range keepSums(ctx, ld, compatRS, loadedZipSumsOnly) {
397 modfetch.TrimGoSum(keep)
399 // commitRequirements below will also call WriteGoSum, but the "keep" map
400 // we have here could be strictly larger: commitRequirements only commits
401 // loaded.requirements, but here we may have also loaded (and want to
402 // preserve checksums for) additional entities from compatRS, which are
403 // only needed for compatibility with ld.TidyCompatibleVersion.
404 modfetch.WriteGoSum(keep)
408 // Success! Update go.mod and go.sum (if needed) and return the results.
410 commitRequirements(ctx, loaded.GoVersion, loaded.requirements)
412 for _, pkg := range ld.pkgs {
414 loadedPackages = append(loadedPackages, pkg.path)
417 sort.Strings(loadedPackages)
418 return matches, loadedPackages
421 // matchLocalDirs is like m.MatchDirs, but tries to avoid scanning directories
422 // outside of the standard library and active modules.
423 func matchLocalDirs(ctx context.Context, m *search.Match, rs *Requirements) {
425 panic(fmt.Sprintf("internal error: resolveLocalDirs on non-local pattern %s", m.Pattern()))
428 if i := strings.Index(m.Pattern(), "..."); i >= 0 {
429 // The pattern is local, but it is a wildcard. Its packages will
430 // only resolve to paths if they are inside of the standard
431 // library, the main module, or some dependency of the main
432 // module. Verify that before we walk the filesystem: a filesystem
433 // walk in a directory like /var or /etc can be very expensive!
434 dir := filepath.Dir(filepath.Clean(m.Pattern()[:i+3]))
436 if !filepath.IsAbs(dir) {
437 absDir = filepath.Join(base.Cwd(), dir)
439 if search.InDir(absDir, cfg.GOROOTsrc) == "" && search.InDir(absDir, ModRoot()) == "" && pathInModuleCache(ctx, absDir, rs) == "" {
441 m.AddError(fmt.Errorf("directory prefix %s outside available modules", base.ShortPath(absDir)))
449 // resolveLocalPackage resolves a filesystem path to a package path.
450 func resolveLocalPackage(ctx context.Context, dir string, rs *Requirements) (string, error) {
452 if filepath.IsAbs(dir) {
453 absDir = filepath.Clean(dir)
455 absDir = filepath.Join(base.Cwd(), dir)
458 bp, err := cfg.BuildContext.ImportDir(absDir, 0)
459 if err != nil && (bp == nil || len(bp.IgnoredGoFiles) == 0) {
460 // golang.org/issue/32917: We should resolve a relative path to a
461 // package path only if the relative path actually contains the code
464 // If the named directory does not exist or contains no Go files,
465 // the package does not exist.
466 // Other errors may affect package loading, but not resolution.
467 if _, err := fsys.Stat(absDir); err != nil {
468 if os.IsNotExist(err) {
469 // Canonicalize OS-specific errors to errDirectoryNotFound so that error
470 // messages will be easier for users to search for.
471 return "", &fs.PathError{Op: "stat", Path: absDir, Err: errDirectoryNotFound}
475 if _, noGo := err.(*build.NoGoError); noGo {
476 // A directory that does not contain any Go source files — even ignored
477 // ones! — is not a Go package, and we can't resolve it to a package
478 // path because that path could plausibly be provided by some other
481 // Any other error indicates that the package “exists” (at least in the
482 // sense that it cannot exist in any other module), but has some other
483 // problem (such as a syntax error).
488 if modRoot != "" && absDir == modRoot {
489 if absDir == cfg.GOROOTsrc {
490 return "", errPkgIsGorootSrc
492 return targetPrefix, nil
495 // Note: The checks for @ here are just to avoid misinterpreting
496 // the module cache directories (formerly GOPATH/src/mod/foo@v1.5.2/bar).
497 // It's not strictly necessary but helpful to keep the checks.
498 if modRoot != "" && strings.HasPrefix(absDir, modRoot+string(filepath.Separator)) && !strings.Contains(absDir[len(modRoot):], "@") {
499 suffix := filepath.ToSlash(absDir[len(modRoot):])
500 if strings.HasPrefix(suffix, "/vendor/") {
501 if cfg.BuildMod != "vendor" {
502 return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
506 pkg := strings.TrimPrefix(suffix, "/vendor/")
507 if _, ok := vendorPkgModule[pkg]; !ok {
508 return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
513 if targetPrefix == "" {
514 pkg := strings.TrimPrefix(suffix, "/")
515 if pkg == "builtin" {
516 // "builtin" is a pseudo-package with a real source file.
517 // It's not included in "std", so it shouldn't resolve from "."
518 // within module "std" either.
519 return "", errPkgIsBuiltin
524 pkg := targetPrefix + suffix
525 if _, ok, err := dirInModule(pkg, targetPrefix, modRoot, true); err != nil {
528 return "", &PackageNotInModuleError{Mod: Target, Pattern: pkg}
533 if sub := search.InDir(absDir, cfg.GOROOTsrc); sub != "" && sub != "." && !strings.Contains(sub, "@") {
534 pkg := filepath.ToSlash(sub)
535 if pkg == "builtin" {
536 return "", errPkgIsBuiltin
541 pkg := pathInModuleCache(ctx, absDir, rs)
543 return "", fmt.Errorf("directory %s outside available modules", base.ShortPath(absDir))
549 errDirectoryNotFound = errors.New("directory not found")
550 errPkgIsGorootSrc = errors.New("GOROOT/src is not an importable package")
551 errPkgIsBuiltin = errors.New(`"builtin" is a pseudo-package, not an importable package`)
554 // pathInModuleCache returns the import path of the directory dir,
555 // if dir is in the module cache copy of a module in our build list.
556 func pathInModuleCache(ctx context.Context, dir string, rs *Requirements) string {
557 tryMod := func(m module.Version) (string, bool) {
560 if repl := Replacement(m); repl.Path != "" && repl.Version == "" {
562 if !filepath.IsAbs(root) {
563 root = filepath.Join(ModRoot(), root)
565 } else if repl.Path != "" {
566 root, err = modfetch.DownloadDir(repl)
568 root, err = modfetch.DownloadDir(m)
574 sub := search.InDir(dir, root)
578 sub = filepath.ToSlash(sub)
579 if strings.Contains(sub, "/vendor/") || strings.HasPrefix(sub, "vendor/") || strings.Contains(sub, "@") {
583 return path.Join(m.Path, filepath.ToSlash(sub)), true
586 if rs.depth == lazy {
587 for _, m := range rs.rootModules {
588 if v, _ := rs.rootSelected(m.Path); v != m.Version {
589 continue // m is a root, but we have a higher root for the same path.
591 if importPath, ok := tryMod(m); ok {
592 // checkMultiplePaths ensures that a module can be used for at most one
593 // requirement, so this must be it.
599 // None of the roots contained dir, or we're in eager mode and want to load
600 // the full module graph more aggressively. Either way, check the full graph
601 // to see if the directory is a non-root dependency.
603 // If the roots are not consistent with the full module graph, the selected
604 // versions of root modules may differ from what we already checked above.
605 // Re-check those paths too.
607 mg, _ := rs.Graph(ctx)
608 var importPath string
609 for _, m := range mg.BuildList() {
611 importPath, found = tryMod(m)
619 // ImportFromFiles adds modules to the build list as needed
620 // to satisfy the imports in the named Go source files.
622 // Errors in missing dependencies are silenced.
624 // TODO(bcmills): Silencing errors seems off. Take a closer look at this and
625 // figure out what the error-reporting actually ought to be.
626 func ImportFromFiles(ctx context.Context, gofiles []string) {
627 rs := LoadModFile(ctx)
629 tags := imports.Tags()
630 imports, testImports, err := imports.ScanFiles(gofiles, tags)
632 base.Fatalf("go: %v", err)
635 loaded = loadFromRoots(ctx, loaderParams{
636 PackageOpts: PackageOpts{
638 ResolveMissingImports: true,
639 SilencePackageErrors: true,
642 listRoots: func(*Requirements) (roots []string) {
643 roots = append(roots, imports...)
644 roots = append(roots, testImports...)
648 commitRequirements(ctx, loaded.GoVersion, loaded.requirements)
651 // DirImportPath returns the effective import path for dir,
652 // provided it is within the main module, or else returns ".".
653 func DirImportPath(ctx context.Context, dir string) string {
657 LoadModFile(ctx) // Sets targetPrefix.
659 if !filepath.IsAbs(dir) {
660 dir = filepath.Join(base.Cwd(), dir)
662 dir = filepath.Clean(dir)
668 if strings.HasPrefix(dir, modRoot+string(filepath.Separator)) {
669 suffix := filepath.ToSlash(dir[len(modRoot):])
670 if strings.HasPrefix(suffix, "/vendor/") {
671 return strings.TrimPrefix(suffix, "/vendor/")
673 return targetPrefix + suffix
678 // ImportMap returns the actual package import path
679 // for an import path found in source code.
680 // If the given import path does not appear in the source code
681 // for the packages that have been loaded, ImportMap returns the empty string.
682 func ImportMap(path string) string {
683 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
690 // PackageDir returns the directory containing the source code
691 // for the package named by the import path.
692 func PackageDir(path string) string {
693 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
700 // PackageModule returns the module providing the package named by the import path.
701 func PackageModule(path string) module.Version {
702 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
704 return module.Version{}
709 // Lookup returns the source directory, import path, and any loading error for
710 // the package at path as imported from the package in parentDir.
711 // Lookup requires that one of the Load functions in this package has already
713 func Lookup(parentPath string, parentIsStd bool, path string) (dir, realPath string, err error) {
715 panic("Lookup called with empty package path")
719 path = loaded.stdVendor(parentPath, path)
721 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
723 // The loader should have found all the relevant paths.
724 // There are a few exceptions, though:
725 // - during go list without -test, the p.Resolve calls to process p.TestImports and p.XTestImports
726 // end up here to canonicalize the import paths.
727 // - during any load, non-loaded packages like "unsafe" end up here.
728 // - during any load, build-injected dependencies like "runtime/cgo" end up here.
729 // - because we ignore appengine/* in the module loader,
730 // the dependencies of any actual appengine/* library end up here.
731 dir := findStandardImportPath(path)
733 return dir, path, nil
735 return "", "", errMissing
737 return pkg.dir, pkg.path, pkg.err
740 // A loader manages the process of loading information about
741 // the required packages for a particular build,
742 // checking that the packages are available in the module set,
743 // and updating the module set if needed.
747 // allClosesOverTests indicates whether the "all" pattern includes
748 // dependencies of tests outside the main module (as in Go 1.11–1.15).
749 // (Otherwise — as in Go 1.16+ — the "all" pattern includes only the packages
750 // transitively *imported by* the packages and tests in the main module.)
751 allClosesOverTests bool
755 // reset on each iteration
757 pkgCache *par.Cache // package path (string) → *loadPkg
758 pkgs []*loadPkg // transitive closure of loaded packages and tests; populated in buildStacks
761 // loaderParams configure the packages loaded by, and the properties reported
762 // by, a loader instance.
763 type loaderParams struct {
765 requirements *Requirements
767 allPatternIsRoot bool // Is the "all" pattern an additional root?
769 listRoots func(rs *Requirements) []string
772 func (ld *loader) reset() {
774 case <-ld.work.Idle():
776 panic("loader.reset when not idle")
780 ld.pkgCache = new(par.Cache)
784 // errorf reports an error via either os.Stderr or base.Errorf,
785 // according to whether ld.AllowErrors is set.
786 func (ld *loader) errorf(format string, args ...interface{}) {
788 fmt.Fprintf(os.Stderr, format, args...)
790 base.Errorf(format, args...)
794 // A loadPkg records information about a single loaded package.
795 type loadPkg struct {
796 // Populated at construction time:
797 path string // import path
800 // Populated at construction time and updated by (*loader).applyPkgFlags:
801 flags atomicLoadPkgFlags
803 // Populated by (*loader).load:
804 mod module.Version // module providing package
805 dir string // directory containing source code
806 err error // error loading package
807 imports []*loadPkg // packages imported by this one
808 testImports []string // test-only imports, saved for use by pkg.test.
811 // Populated by (*loader).pkgTest:
815 // Populated by postprocessing in (*loader).buildStacks:
816 stack *loadPkg // package importing this one in minimal import stack for this pkg
819 // loadPkgFlags is a set of flags tracking metadata about a package.
820 type loadPkgFlags int8
823 // pkgInAll indicates that the package is in the "all" package pattern,
824 // regardless of whether we are loading the "all" package pattern.
826 // When the pkgInAll flag and pkgImportsLoaded flags are both set, the caller
827 // who set the last of those flags must propagate the pkgInAll marking to all
828 // of the imports of the marked package.
830 // A test is marked with pkgInAll if that test would promote the packages it
831 // imports to be in "all" (such as when the test is itself within the main
832 // module, or when ld.allClosesOverTests is true).
833 pkgInAll loadPkgFlags = 1 << iota
835 // pkgIsRoot indicates that the package matches one of the root package
836 // patterns requested by the caller.
838 // If LoadTests is set, then when pkgIsRoot and pkgImportsLoaded are both set,
839 // the caller who set the last of those flags must populate a test for the
840 // package (in the pkg.test field).
842 // If the "all" pattern is included as a root, then non-test packages in "all"
843 // are also roots (and must be marked pkgIsRoot).
846 // pkgFromRoot indicates that the package is in the transitive closure of
847 // imports starting at the roots. (Note that every package marked as pkgIsRoot
848 // is also trivially marked pkgFromRoot.)
851 // pkgImportsLoaded indicates that the imports and testImports fields of a
852 // loadPkg have been populated.
856 // has reports whether all of the flags in cond are set in f.
857 func (f loadPkgFlags) has(cond loadPkgFlags) bool {
858 return f&cond == cond
861 // An atomicLoadPkgFlags stores a loadPkgFlags for which individual flags can be
863 type atomicLoadPkgFlags struct {
867 // update sets the given flags in af (in addition to any flags already set).
869 // update returns the previous flag state so that the caller may determine which
870 // flags were newly-set.
871 func (af *atomicLoadPkgFlags) update(flags loadPkgFlags) (old loadPkgFlags) {
873 old := atomic.LoadInt32(&af.bits)
874 new := old | int32(flags)
875 if new == old || atomic.CompareAndSwapInt32(&af.bits, old, new) {
876 return loadPkgFlags(old)
881 // has reports whether all of the flags in cond are set in af.
882 func (af *atomicLoadPkgFlags) has(cond loadPkgFlags) bool {
883 return loadPkgFlags(atomic.LoadInt32(&af.bits))&cond == cond
886 // isTest reports whether pkg is a test of another package.
887 func (pkg *loadPkg) isTest() bool {
888 return pkg.testOf != nil
891 // fromExternalModule reports whether pkg was loaded from a module other than
893 func (pkg *loadPkg) fromExternalModule() bool {
894 if pkg.mod.Path == "" {
895 return false // loaded from the standard library, not a module
897 if pkg.mod.Path == Target.Path {
898 return false // loaded from the main module.
903 var errMissing = errors.New("cannot find package")
905 // loadFromRoots attempts to load the build graph needed to process a set of
906 // root packages and their dependencies.
908 // The set of root packages is returned by the params.listRoots function, and
909 // expanded to the full set of packages by tracing imports (and possibly tests)
911 func loadFromRoots(ctx context.Context, params loaderParams) *loader {
913 loaderParams: params,
914 work: par.NewQueue(runtime.GOMAXPROCS(0)),
917 if ld.GoVersion == "" {
918 ld.GoVersion = modFileGoVersion()
920 if ld.Tidy && semver.Compare("v"+ld.GoVersion, "v"+LatestGoVersion()) > 0 {
921 ld.errorf("go mod tidy: go.mod file indicates go %s, but maximum supported version is %s\n", ld.GoVersion, LatestGoVersion())
927 if ld.TidyCompatibleVersion == "" {
928 ld.TidyCompatibleVersion = priorGoVersion(ld.GoVersion)
929 } else if semver.Compare("v"+ld.TidyCompatibleVersion, "v"+ld.GoVersion) > 0 {
930 // Each version of the Go toolchain knows how to interpret go.mod and
931 // go.sum files produced by all previous versions, so a compatibility
932 // version higher than the go.mod version adds nothing.
933 ld.TidyCompatibleVersion = ld.GoVersion
937 if semver.Compare("v"+ld.GoVersion, narrowAllVersionV) < 0 && !ld.UseVendorAll {
938 // The module's go version explicitly predates the change in "all" for lazy
939 // loading, so continue to use the older interpretation.
940 ld.allClosesOverTests = true
944 ld.requirements, err = convertDepth(ctx, ld.requirements, modDepthFromGoVersion(ld.GoVersion))
946 ld.errorf("go: %v\n", err)
949 if ld.requirements.depth == eager {
951 ld.requirements, _, err = expandGraph(ctx, ld.requirements)
953 ld.errorf("go: %v\n", err)
960 // Load the root packages and their imports.
961 // Note: the returned roots can change on each iteration,
962 // since the expansion of package patterns depends on the
963 // build list we're using.
964 rootPkgs := ld.listRoots(ld.requirements)
966 if ld.requirements.depth == lazy && cfg.BuildMod == "mod" {
967 // Before we start loading transitive imports of packages, locate all of
968 // the root packages and promote their containing modules to root modules
969 // dependencies. If their go.mod files are tidy (the common case) and the
970 // set of root packages does not change then we can select the correct
971 // versions of all transitive imports on the first try and complete
972 // loading in a single iteration.
973 changedBuildList := ld.preloadRootModules(ctx, rootPkgs)
974 if changedBuildList {
975 // The build list has changed, so the set of root packages may have also
976 // changed. Start over to pick up the changes. (Preloading roots is much
977 // cheaper than loading the full import graph, so we would rather pay
978 // for an extra iteration of preloading than potentially end up
979 // discarding the result of a full iteration of loading.)
984 inRoots := map[*loadPkg]bool{}
985 for _, path := range rootPkgs {
986 root := ld.pkg(ctx, path, pkgIsRoot)
988 ld.roots = append(ld.roots, root)
993 // ld.pkg adds imported packages to the work queue and calls applyPkgFlags,
994 // which adds tests (and test dependencies) as needed.
996 // When all of the work in the queue has completed, we'll know that the
997 // transitive closure of dependencies has been loaded.
1002 changed, err := ld.updateRequirements(ctx)
1004 ld.errorf("go: %v\n", err)
1008 // Don't resolve missing imports until the module graph have stabilized.
1009 // If the roots are still changing, they may turn out to specify a
1010 // requirement on the missing package(s), and we would rather use a
1011 // version specified by a new root than add a new dependency on an
1012 // unrelated version.
1016 if !ld.ResolveMissingImports || (!HasModRoot() && !allowMissingModuleImports) {
1017 // We've loaded as much as we can without resolving missing imports.
1021 modAddedBy := ld.resolveMissingImports(ctx)
1022 if len(modAddedBy) == 0 {
1023 // The roots are stable, and we've resolved all of the missing packages
1028 toAdd := make([]module.Version, 0, len(modAddedBy))
1029 for m, _ := range modAddedBy {
1030 toAdd = append(toAdd, m)
1032 module.Sort(toAdd) // to make errors deterministic
1034 // We ran updateRequirements before resolving missing imports and it didn't
1035 // make any changes, so we know that the requirement graph is already
1036 // consistent with ld.pkgs: we don't need to pass ld.pkgs to updateRoots
1037 // again. (That would waste time looking for changes that we have already
1039 var noPkgs []*loadPkg
1040 // We also know that we're going to call updateRequirements again next
1041 // iteration so we don't need to also update it here. (That would waste time
1042 // computing a "direct" map that we'll have to recompute later anyway.)
1043 direct := ld.requirements.direct
1044 rs, err := updateRoots(ctx, direct, ld.requirements, noPkgs, toAdd, ld.AssumeRootsImported)
1046 // If an error was found in a newly added module, report the package
1047 // import stack instead of the module requirement stack. Packages
1048 // are more descriptive.
1049 if err, ok := err.(*mvs.BuildListError); ok {
1050 if pkg := modAddedBy[err.Module()]; pkg != nil {
1051 ld.errorf("go: %s: %v\n", pkg.stackText(), err.Err)
1055 ld.errorf("go: %v\n", err)
1058 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1059 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1060 // set of modules to add to the graph, but adding those modules had no
1061 // effect — either they were already in the graph, or updateRoots did not
1062 // add them as requested.
1063 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1065 ld.requirements = rs
1067 base.ExitIfErrors() // TODO(bcmills): Is this actually needed?
1069 // Tidy the build list, if applicable, before we report errors.
1070 // (The process of tidying may remove errors from irrelevant dependencies.)
1072 rs, err := tidyRoots(ctx, ld.requirements, ld.pkgs)
1074 ld.errorf("go: %v\n", err)
1077 if ld.requirements.depth == lazy {
1078 // We continuously add tidy roots to ld.requirements during loading, so at
1079 // this point the tidy roots should be a subset of the roots of
1080 // ld.requirements, ensuring that no new dependencies are brought inside
1081 // the lazy-loading horizon.
1082 // If that is not the case, there is a bug in the loading loop above.
1083 for _, m := range rs.rootModules {
1084 if v, ok := ld.requirements.rootSelected(m.Path); !ok || v != m.Version {
1085 ld.errorf("go mod tidy: internal error: a requirement on %v is needed but was not added during package loading\n", m)
1090 ld.requirements = rs
1093 // Report errors, if any.
1094 for _, pkg := range ld.pkgs {
1099 // Add importer information to checksum errors.
1100 if sumErr := (*ImportMissingSumError)(nil); errors.As(pkg.err, &sumErr) {
1101 if importer := pkg.stack; importer != nil {
1102 sumErr.importer = importer.path
1103 sumErr.importerVersion = importer.mod.Version
1104 sumErr.importerIsTest = importer.testOf != nil
1108 if ld.SilencePackageErrors {
1111 if stdErr := (*ImportMissingError)(nil); errors.As(pkg.err, &stdErr) &&
1112 stdErr.isStd && ld.SilenceMissingStdImports {
1115 if ld.SilenceNoGoErrors && errors.Is(pkg.err, imports.ErrNoGo) {
1119 ld.errorf("%s: %v\n", pkg.stackText(), pkg.err)
1122 ld.checkMultiplePaths()
1126 // updateRequirements ensures that ld.requirements is consistent with the
1127 // information gained from ld.pkgs and includes the modules in add as roots at
1128 // at least the given versions.
1132 // - Modules that provide packages directly imported from the main module are
1133 // marked as direct, and are promoted to explicit roots. If a needed root
1134 // cannot be promoted due to -mod=readonly or -mod=vendor, the importing
1135 // package is marked with an error.
1137 // - If ld scanned the "all" pattern independent of build constraints, it is
1138 // guaranteed to have seen every direct import. Module dependencies that did
1139 // not provide any directly-imported package are then marked as indirect.
1141 // - Root dependencies are updated to their selected versions.
1143 // The "changed" return value reports whether the update changed the selected
1144 // version of any module that either provided a loaded package or may now
1145 // provide a package that was previously unresolved.
1146 func (ld *loader) updateRequirements(ctx context.Context) (changed bool, err error) {
1147 rs := ld.requirements
1149 // direct contains the set of modules believed to provide packages directly
1150 // imported by the main module.
1151 var direct map[string]bool
1153 // If we didn't scan all of the imports from the main module, or didn't use
1154 // imports.AnyTags, then we didn't necessarily load every package that
1155 // contributes “direct” imports — so we can't safely mark existing direct
1156 // dependencies in ld.requirements as indirect-only. Propagate them as direct.
1157 loadedDirect := ld.allPatternIsRoot && reflect.DeepEqual(ld.Tags, imports.AnyTags())
1159 direct = make(map[string]bool)
1161 // TODO(bcmills): It seems like a shame to allocate and copy a map here when
1162 // it will only rarely actually vary from rs.direct. Measure this cost and
1163 // maybe avoid the copy.
1164 direct = make(map[string]bool, len(rs.direct))
1165 for mPath := range rs.direct {
1166 direct[mPath] = true
1170 for _, pkg := range ld.pkgs {
1171 if pkg.mod != Target {
1174 for _, dep := range pkg.imports {
1175 if !dep.fromExternalModule() {
1179 if pkg.err == nil && cfg.BuildMod != "mod" {
1180 if v, ok := rs.rootSelected(dep.mod.Path); !ok || v != dep.mod.Version {
1181 // dep.mod is not an explicit dependency, but needs to be.
1182 // Because we are not in "mod" mode, we will not be able to update it.
1183 // Instead, mark the importing package with an error.
1185 // TODO(#41688): The resulting error message fails to include the file
1186 // position of the import statement (because that information is not
1187 // tracked by the module loader). Figure out how to plumb the import
1188 // position through.
1189 pkg.err = &DirectImportFromImplicitDependencyError{
1190 ImporterPath: pkg.path,
1191 ImportedPath: dep.path,
1194 // cfg.BuildMod does not allow us to change dep.mod to be a direct
1195 // dependency, so don't mark it as such.
1200 // dep is a package directly imported by a package or test in the main
1201 // module and loaded from some other module (not the standard library).
1202 // Mark its module as a direct dependency.
1203 direct[dep.mod.Path] = true
1207 var addRoots []module.Version
1209 // When we are tidying a lazy module, we may need to add roots to preserve
1210 // the versions of indirect, test-only dependencies that are upgraded
1211 // above or otherwise missing from the go.mod files of direct
1212 // dependencies. (For example, the direct dependency might be a very
1213 // stable codebase that predates modules and thus lacks a go.mod file, or
1214 // the author of the direct dependency may have forgotten to commit a
1215 // change to the go.mod file, or may have made an erroneous hand-edit that
1216 // causes it to be untidy.)
1218 // Promoting an indirect dependency to a root adds the next layer of its
1219 // dependencies to the module graph, which may increase the selected
1220 // versions of other modules from which we have already loaded packages.
1221 // So after we promote an indirect dependency to a root, we need to reload
1222 // packages, which means another iteration of loading.
1224 // As an extra wrinkle, the upgrades due to promoting a root can cause
1225 // previously-resolved packages to become unresolved. For example, the
1226 // module providing an unstable package might be upgraded to a version
1227 // that no longer contains that package. If we then resolve the missing
1228 // package, we might add yet another root that upgrades away some other
1229 // dependency. (The tests in mod_tidy_convergence*.txt illustrate some
1230 // particularly worrisome cases.)
1232 // To ensure that this process of promoting, adding, and upgrading roots
1233 // eventually terminates, during iteration we only ever add modules to the
1234 // root set — we only remove irrelevant roots at the very end of
1235 // iteration, after we have already added every root that we plan to need
1236 // in the (eventual) tidy root set.
1238 // Since we do not remove any roots during iteration, even if they no
1239 // longer provide any imported packages, the selected versions of the
1240 // roots can only increase and the set of roots can only expand. The set
1241 // of extant root paths is finite and the set of versions of each path is
1242 // finite, so the iteration *must* reach a stable fixed-point.
1243 tidy, err := tidyRoots(ctx, rs, ld.pkgs)
1247 addRoots = tidy.rootModules
1250 rs, err = updateRoots(ctx, direct, rs, ld.pkgs, addRoots, ld.AssumeRootsImported)
1252 // We don't actually know what even the root requirements are supposed to be,
1253 // so we can't proceed with loading. Return the error to the caller
1257 if rs != ld.requirements && !reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1258 // The roots of the module graph have changed in some way (not just the
1259 // "direct" markings). Check whether the changes affected any of the loaded
1261 mg, err := rs.Graph(ctx)
1265 for _, pkg := range ld.pkgs {
1266 if pkg.fromExternalModule() && mg.Selected(pkg.mod.Path) != pkg.mod.Version {
1271 // Promoting a module to a root may resolve an import that was
1272 // previously missing (by pulling in a previously-prune dependency that
1273 // provides it) or ambiguous (by promoting exactly one of the
1274 // alternatives to a root and ignoring the second-level alternatives) or
1275 // otherwise errored out (by upgrading from a version that cannot be
1276 // fetched to one that can be).
1278 // Instead of enumerating all of the possible errors, we'll just check
1279 // whether importFromModules returns nil for the package.
1280 // False-positives are ok: if we have a false-positive here, we'll do an
1281 // extra iteration of package loading this time, but we'll still
1282 // converge when the root set stops changing.
1284 // In some sense, we can think of this as ‘upgraded the module providing
1285 // pkg.path from "none" to a version higher than "none"’.
1286 if _, _, err = importFromModules(ctx, pkg.path, rs, nil); err == nil {
1294 ld.requirements = rs
1298 // resolveMissingImports returns a set of modules that could be added as
1299 // dependencies in order to resolve missing packages from pkgs.
1301 // The newly-resolved packages are added to the addedModuleFor map, and
1302 // resolveMissingImports returns a map from each new module version to
1303 // the first missing package that module would resolve.
1304 func (ld *loader) resolveMissingImports(ctx context.Context) (modAddedBy map[module.Version]*loadPkg) {
1305 type pkgMod struct {
1309 var pkgMods []pkgMod
1310 for _, pkg := range ld.pkgs {
1315 // If we are missing a test, we are also missing its non-test version, and
1316 // we should only add the missing import once.
1319 if !errors.As(pkg.err, new(*ImportMissingError)) {
1320 // Leave other errors for Import or load.Packages to report.
1325 var mod module.Version
1326 ld.work.Add(func() {
1328 mod, err = queryImport(ctx, pkg.path, ld.requirements)
1330 // pkg.err was already non-nil, so we can reasonably attribute the error
1331 // for pkg to either the original error or the one returned by
1332 // queryImport. The existing error indicates only that we couldn't find
1333 // the package, whereas the query error also explains why we didn't fix
1334 // the problem — so we prefer the latter.
1338 // err is nil, but we intentionally leave pkg.err non-nil and pkg.mod
1339 // unset: we still haven't satisfied other invariants of a
1340 // successfully-loaded package, such as scanning and loading the imports
1341 // of that package. If we succeed in resolving the new dependency graph,
1342 // the caller can reload pkg and update the error at that point.
1344 // Even then, the package might not be loaded from the version we've
1345 // identified here. The module may be upgraded by some other dependency,
1346 // or by a transitive dependency of mod itself, or — less likely — the
1347 // package may be rejected by an AllowPackage hook or rendered ambiguous
1348 // by some other newly-added or newly-upgraded dependency.
1351 pkgMods = append(pkgMods, pkgMod{pkg: pkg, mod: &mod})
1355 modAddedBy = map[module.Version]*loadPkg{}
1356 for _, pm := range pkgMods {
1357 pkg, mod := pm.pkg, *pm.mod
1362 fmt.Fprintf(os.Stderr, "go: found %s in %s %s\n", pkg.path, mod.Path, mod.Version)
1363 if modAddedBy[mod] == nil {
1364 modAddedBy[mod] = pkg
1371 // pkg locates the *loadPkg for path, creating and queuing it for loading if
1372 // needed, and updates its state to reflect the given flags.
1374 // The imports of the returned *loadPkg will be loaded asynchronously in the
1375 // ld.work queue, and its test (if requested) will also be populated once
1376 // imports have been resolved. When ld.work goes idle, all transitive imports of
1377 // the requested package (and its test, if requested) will have been loaded.
1378 func (ld *loader) pkg(ctx context.Context, path string, flags loadPkgFlags) *loadPkg {
1379 if flags.has(pkgImportsLoaded) {
1380 panic("internal error: (*loader).pkg called with pkgImportsLoaded flag set")
1383 pkg := ld.pkgCache.Do(path, func() interface{} {
1387 ld.applyPkgFlags(ctx, pkg, flags)
1389 ld.work.Add(func() { ld.load(ctx, pkg) })
1393 ld.applyPkgFlags(ctx, pkg, flags)
1397 // applyPkgFlags updates pkg.flags to set the given flags and propagate the
1398 // (transitive) effects of those flags, possibly loading or enqueueing further
1399 // packages as a result.
1400 func (ld *loader) applyPkgFlags(ctx context.Context, pkg *loadPkg, flags loadPkgFlags) {
1405 if flags.has(pkgInAll) && ld.allPatternIsRoot && !pkg.isTest() {
1406 // This package matches a root pattern by virtue of being in "all".
1409 if flags.has(pkgIsRoot) {
1410 flags |= pkgFromRoot
1413 old := pkg.flags.update(flags)
1415 if new == old || !new.has(pkgImportsLoaded) {
1416 // We either didn't change the state of pkg, or we don't know anything about
1417 // its dependencies yet. Either way, we can't usefully load its test or
1418 // update its dependencies.
1423 // Check whether we should add (or update the flags for) a test for pkg.
1424 // ld.pkgTest is idempotent and extra invocations are inexpensive,
1425 // so it's ok if we call it more than is strictly necessary.
1428 case ld.allPatternIsRoot && pkg.mod == Target:
1429 // We are loading the "all" pattern, which includes packages imported by
1430 // tests in the main module. This package is in the main module, so we
1431 // need to identify the imports of its test even if LoadTests is not set.
1433 // (We will filter out the extra tests explicitly in computePatternAll.)
1436 case ld.allPatternIsRoot && ld.allClosesOverTests && new.has(pkgInAll):
1437 // This variant of the "all" pattern includes imports of tests of every
1438 // package that is itself in "all", and pkg is in "all", so its test is
1439 // also in "all" (as above).
1442 case ld.LoadTests && new.has(pkgIsRoot):
1443 // LoadTest explicitly requests tests of “the root packages”.
1448 var testFlags loadPkgFlags
1449 if pkg.mod == Target || (ld.allClosesOverTests && new.has(pkgInAll)) {
1450 // Tests of packages in the main module are in "all", in the sense that
1451 // they cause the packages they import to also be in "all". So are tests
1452 // of packages in "all" if "all" closes over test dependencies.
1453 testFlags |= pkgInAll
1455 ld.pkgTest(ctx, pkg, testFlags)
1459 if new.has(pkgInAll) && !old.has(pkgInAll|pkgImportsLoaded) {
1460 // We have just marked pkg with pkgInAll, or we have just loaded its
1461 // imports, or both. Now is the time to propagate pkgInAll to the imports.
1462 for _, dep := range pkg.imports {
1463 ld.applyPkgFlags(ctx, dep, pkgInAll)
1467 if new.has(pkgFromRoot) && !old.has(pkgFromRoot|pkgImportsLoaded) {
1468 for _, dep := range pkg.imports {
1469 ld.applyPkgFlags(ctx, dep, pkgFromRoot)
1474 // preloadRootModules loads the module requirements needed to identify the
1475 // selected version of each module providing a package in rootPkgs,
1476 // adding new root modules to the module graph if needed.
1477 func (ld *loader) preloadRootModules(ctx context.Context, rootPkgs []string) (changedBuildList bool) {
1478 needc := make(chan map[module.Version]bool, 1)
1479 needc <- map[module.Version]bool{}
1480 for _, path := range rootPkgs {
1482 ld.work.Add(func() {
1483 // First, try to identify the module containing the package using only roots.
1485 // If the main module is tidy and the package is in "all" — or if we're
1486 // lucky — we can identify all of its imports without actually loading the
1487 // full module graph.
1488 m, _, err := importFromModules(ctx, path, ld.requirements, nil)
1490 var missing *ImportMissingError
1491 if errors.As(err, &missing) && ld.ResolveMissingImports {
1492 // This package isn't provided by any selected module.
1493 // If we can find it, it will be a new root dependency.
1494 m, err = queryImport(ctx, path, ld.requirements)
1497 // We couldn't identify the root module containing this package.
1498 // Leave it unresolved; we will report it during loading.
1503 // The package is in std or cmd. We don't need to change the root set.
1507 v, ok := ld.requirements.rootSelected(m.Path)
1508 if !ok || v != m.Version {
1509 // We found the requested package in m, but m is not a root, so
1510 // loadModGraph will not load its requirements. We need to promote the
1511 // module to a root to ensure that any other packages this package
1512 // imports are resolved from correct dependency versions.
1514 // (This is the “argument invariant” from the lazy loading design.)
1525 return false // No roots to add.
1528 toAdd := make([]module.Version, 0, len(need))
1529 for m := range need {
1530 toAdd = append(toAdd, m)
1534 rs, err := updateRoots(ctx, ld.requirements.direct, ld.requirements, nil, toAdd, ld.AssumeRootsImported)
1536 // We are missing some root dependency, and for some reason we can't load
1537 // enough of the module dependency graph to add the missing root. Package
1538 // loading is doomed to fail, so fail quickly.
1539 ld.errorf("go: %v\n", err)
1543 if reflect.DeepEqual(rs.rootModules, ld.requirements.rootModules) {
1544 // Something is deeply wrong. resolveMissingImports gave us a non-empty
1545 // set of modules to add to the graph, but adding those modules had no
1546 // effect — either they were already in the graph, or updateRoots did not
1547 // add them as requested.
1548 panic(fmt.Sprintf("internal error: adding %v to module graph had no effect on root requirements (%v)", toAdd, rs.rootModules))
1551 ld.requirements = rs
1555 // load loads an individual package.
1556 func (ld *loader) load(ctx context.Context, pkg *loadPkg) {
1557 if strings.Contains(pkg.path, "@") {
1558 // Leave for error during load.
1561 if build.IsLocalImport(pkg.path) || filepath.IsAbs(pkg.path) {
1562 // Leave for error during load.
1563 // (Module mode does not allow local imports.)
1567 if search.IsMetaPackage(pkg.path) {
1568 pkg.err = &invalidImportError{
1569 importPath: pkg.path,
1570 err: fmt.Errorf("%q is not an importable package; see 'go help packages'", pkg.path),
1576 if ld.requirements.depth == eager {
1578 mg, err = ld.requirements.Graph(ctx)
1580 // We already checked the error from Graph in loadFromRoots and/or
1581 // updateRequirements, so we ignored the error on purpose and we should
1582 // keep trying to push past it.
1584 // However, because mg may be incomplete (and thus may select inaccurate
1585 // versions), we shouldn't use it to load packages. Instead, we pass a nil
1586 // *ModuleGraph, which will cause mg to first try loading from only the
1587 // main module and root dependencies.
1592 pkg.mod, pkg.dir, pkg.err = importFromModules(ctx, pkg.path, ld.requirements, mg)
1596 if pkg.mod == Target {
1597 // Go ahead and mark pkg as in "all". This provides the invariant that a
1598 // package that is *only* imported by other packages in "all" is always
1599 // marked as such before loading its imports.
1601 // We don't actually rely on that invariant at the moment, but it may
1602 // improve efficiency somewhat and makes the behavior a bit easier to reason
1603 // about (by reducing churn on the flag bits of dependencies), and costs
1604 // essentially nothing (these atomic flag ops are essentially free compared
1605 // to scanning source code for imports).
1606 ld.applyPkgFlags(ctx, pkg, pkgInAll)
1608 if ld.AllowPackage != nil {
1609 if err := ld.AllowPackage(ctx, pkg.path, pkg.mod); err != nil {
1614 pkg.inStd = (search.IsStandardImportPath(pkg.path) && search.InDir(pkg.dir, cfg.GOROOTsrc) != "")
1616 var imports, testImports []string
1618 if cfg.BuildContext.Compiler == "gccgo" && pkg.inStd {
1619 // We can't scan standard packages for gccgo.
1622 imports, testImports, err = scanDir(pkg.dir, ld.Tags)
1629 pkg.imports = make([]*loadPkg, 0, len(imports))
1630 var importFlags loadPkgFlags
1631 if pkg.flags.has(pkgInAll) {
1632 importFlags = pkgInAll
1634 for _, path := range imports {
1636 // Imports from packages in "std" and "cmd" should resolve using
1637 // GOROOT/src/vendor even when "std" is not the main module.
1638 path = ld.stdVendor(pkg.path, path)
1640 pkg.imports = append(pkg.imports, ld.pkg(ctx, path, importFlags))
1642 pkg.testImports = testImports
1644 ld.applyPkgFlags(ctx, pkg, pkgImportsLoaded)
1647 // pkgTest locates the test of pkg, creating it if needed, and updates its state
1648 // to reflect the given flags.
1650 // pkgTest requires that the imports of pkg have already been loaded (flagged
1651 // with pkgImportsLoaded).
1652 func (ld *loader) pkgTest(ctx context.Context, pkg *loadPkg, testFlags loadPkgFlags) *loadPkg {
1654 panic("pkgTest called on a test package")
1657 createdTest := false
1658 pkg.testOnce.Do(func() {
1659 pkg.test = &loadPkg{
1667 ld.applyPkgFlags(ctx, pkg.test, testFlags)
1673 test.imports = make([]*loadPkg, 0, len(pkg.testImports))
1674 var importFlags loadPkgFlags
1675 if test.flags.has(pkgInAll) {
1676 importFlags = pkgInAll
1678 for _, path := range pkg.testImports {
1680 path = ld.stdVendor(test.path, path)
1682 test.imports = append(test.imports, ld.pkg(ctx, path, importFlags))
1684 pkg.testImports = nil
1685 ld.applyPkgFlags(ctx, test, pkgImportsLoaded)
1687 ld.applyPkgFlags(ctx, test, testFlags)
1693 // stdVendor returns the canonical import path for the package with the given
1694 // path when imported from the standard-library package at parentPath.
1695 func (ld *loader) stdVendor(parentPath, path string) string {
1696 if search.IsStandardImportPath(path) {
1700 if str.HasPathPrefix(parentPath, "cmd") {
1701 if !ld.VendorModulesInGOROOTSrc || Target.Path != "cmd" {
1702 vendorPath := pathpkg.Join("cmd", "vendor", path)
1703 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1707 } else if !ld.VendorModulesInGOROOTSrc || Target.Path != "std" || str.HasPathPrefix(parentPath, "vendor") {
1708 // If we are outside of the 'std' module, resolve imports from within 'std'
1709 // to the vendor directory.
1711 // Do the same for importers beginning with the prefix 'vendor/' even if we
1712 // are *inside* of the 'std' module: the 'vendor/' packages that resolve
1713 // globally from GOROOT/src/vendor (and are listed as part of 'go list std')
1714 // are distinct from the real module dependencies, and cannot import
1715 // internal packages from the real module.
1717 // (Note that although the 'vendor/' packages match the 'std' *package*
1718 // pattern, they are not part of the std *module*, and do not affect
1719 // 'go mod tidy' and similar module commands when working within std.)
1720 vendorPath := pathpkg.Join("vendor", path)
1721 if _, err := os.Stat(filepath.Join(cfg.GOROOTsrc, filepath.FromSlash(vendorPath))); err == nil {
1726 // Not vendored: resolve from modules.
1730 // computePatternAll returns the list of packages matching pattern "all",
1731 // starting with a list of the import paths for the packages in the main module.
1732 func (ld *loader) computePatternAll() (all []string) {
1733 for _, pkg := range ld.pkgs {
1734 if pkg.flags.has(pkgInAll) && !pkg.isTest() {
1735 all = append(all, pkg.path)
1742 // checkMultiplePaths verifies that a given module path is used as itself
1743 // or as a replacement for another module, but not both at the same time.
1745 // (See https://golang.org/issue/26607 and https://golang.org/issue/34650.)
1746 func (ld *loader) checkMultiplePaths() {
1747 mods := ld.requirements.rootModules
1748 if cached := ld.requirements.graph.Load(); cached != nil {
1749 if mg := cached.(cachedGraph).mg; mg != nil {
1750 mods = mg.BuildList()
1754 firstPath := map[module.Version]string{}
1755 for _, mod := range mods {
1756 src := resolveReplacement(mod)
1757 if prev, ok := firstPath[src]; !ok {
1758 firstPath[src] = mod.Path
1759 } else if prev != mod.Path {
1760 ld.errorf("go: %s@%s used for two different module paths (%s and %s)\n", src.Path, src.Version, prev, mod.Path)
1765 // checkTidyCompatibility emits an error if any package would be loaded from a
1766 // different module under rs than under ld.requirements.
1767 func (ld *loader) checkTidyCompatibility(ctx context.Context, rs *Requirements) {
1768 suggestUpgrade := false
1769 suggestEFlag := false
1770 suggestFixes := func() {
1772 // The user is explicitly ignoring these errors, so don't bother them with
1777 // We print directly to os.Stderr because this information is advice about
1778 // how to fix errors, not actually an error itself.
1779 // (The actual errors should have been logged already.)
1781 fmt.Fprintln(os.Stderr)
1784 if ld.GoVersion != modFileGoVersion() {
1785 goFlag = " -go=" + ld.GoVersion
1789 if ld.TidyCompatibleVersion != priorGoVersion(ld.GoVersion) {
1790 compatFlag = " -compat=" + ld.TidyCompatibleVersion
1796 eDesc = ", leaving some packages unresolved"
1799 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)
1800 } else if suggestEFlag {
1801 // If some packages are missing but no package is upgraded, then we
1802 // shouldn't suggest upgrading to the Go 1.16 versions explicitly — that
1803 // wouldn't actually fix anything for Go 1.16 users, and *would* break
1804 // something for Go 1.17 users.
1805 fmt.Fprintf(os.Stderr, "To proceed despite packages unresolved in go %s:\n\tgo mod tidy -e%s%s\n", ld.TidyCompatibleVersion, goFlag, compatFlag)
1808 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)
1810 // TODO(#46141): Populate the linked wiki page.
1811 fmt.Fprintf(os.Stderr, "For other options, see:\n\thttps://golang.org/doc/modules/pruning\n")
1814 mg, err := rs.Graph(ctx)
1816 ld.errorf("go mod tidy: error loading go %s module graph: %v\n", ld.TidyCompatibleVersion, err)
1821 // Re-resolve packages in parallel.
1823 // We re-resolve each package — rather than just checking versions — to ensure
1824 // that we have fetched module source code (and, importantly, checksums for
1825 // that source code) for all modules that are necessary to ensure that imports
1826 // are unambiguous. That also produces clearer diagnostics, since we can say
1827 // exactly what happened to the package if it became ambiguous or disappeared
1830 // We re-resolve the packages in parallel because this process involves disk
1831 // I/O to check for package sources, and because the process of checking for
1832 // ambiguous imports may require us to download additional modules that are
1833 // otherwise pruned out in Go 1.17 — we don't want to block progress on other
1834 // packages while we wait for a single new download.
1835 type mismatch struct {
1839 mismatchMu := make(chan map[*loadPkg]mismatch, 1)
1840 mismatchMu <- map[*loadPkg]mismatch{}
1841 for _, pkg := range ld.pkgs {
1842 if pkg.mod.Path == "" && pkg.err == nil {
1843 // This package is from the standard library (which does not vary based on
1844 // the module graph).
1849 ld.work.Add(func() {
1850 mod, _, err := importFromModules(ctx, pkg.path, rs, mg)
1852 mismatches := <-mismatchMu
1853 mismatches[pkg] = mismatch{mod: mod, err: err}
1854 mismatchMu <- mismatches
1860 mismatches := <-mismatchMu
1861 if len(mismatches) == 0 {
1862 // Since we're running as part of 'go mod tidy', the roots of the module
1863 // graph should contain only modules that are relevant to some package in
1864 // the package graph. We checked every package in the package graph and
1865 // didn't find any mismatches, so that must mean that all of the roots of
1866 // the module graph are also consistent.
1868 // If we're wrong, Go 1.16 in -mod=readonly mode will error out with
1869 // "updates to go.mod needed", which would be very confusing. So instead,
1870 // we'll double-check that our reasoning above actually holds — if it
1871 // doesn't, we'll emit an internal error and hopefully the user will report
1873 for _, m := range ld.requirements.rootModules {
1874 if v := mg.Selected(m.Path); v != m.Version {
1875 fmt.Fprintln(os.Stderr)
1876 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)
1882 // Iterate over the packages (instead of the mismatches map) to emit errors in
1883 // deterministic order.
1884 for _, pkg := range ld.pkgs {
1885 mismatch, ok := mismatches[pkg]
1891 // We already did (or will) report an error for the package itself,
1892 // so don't report a duplicate (and more vebose) error for its test.
1893 if _, ok := mismatches[pkg.testOf]; !ok {
1894 base.Fatalf("go: internal error: mismatch recorded for test %s, but not its non-test package", pkg.path)
1900 case mismatch.err != nil:
1901 // pkg resolved successfully, but errors out using the requirements in rs.
1903 // This could occur because the import is provided by a single lazy root
1904 // (and is thus unambiguous in lazy mode) and also one or more
1905 // transitive dependencies (and is ambiguous in eager mode).
1907 // It could also occur because some transitive dependency upgrades the
1908 // module that previously provided the package to a version that no
1909 // longer does, or to a version for which the module source code (but
1910 // not the go.mod file in isolation) has a checksum error.
1911 if missing := (*ImportMissingError)(nil); errors.As(mismatch.err, &missing) {
1912 selected := module.Version{
1914 Version: mg.Selected(pkg.mod.Path),
1916 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)
1918 if ambiguous := (*AmbiguousImportError)(nil); errors.As(mismatch.err, &ambiguous) {
1919 // TODO: Is this check needed?
1921 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)
1926 // Even if we press ahead with the '-e' flag, the older version will
1927 // error out in readonly mode if it thinks the go.mod file contains
1928 // any *explicit* dependency that is not at its selected version,
1929 // even if that dependency is not relevant to any package being loaded.
1931 // We check for that condition here. If all of the roots are consistent
1932 // the '-e' flag suffices, but otherwise we need to suggest an upgrade.
1933 if !suggestUpgrade {
1934 for _, m := range ld.requirements.rootModules {
1935 if v := mg.Selected(m.Path); v != m.Version {
1936 suggestUpgrade = true
1942 case pkg.err != nil:
1943 // pkg had an error in lazy mode (presumably suppressed with the -e flag),
1944 // but not in eager mode.
1946 // This is possible, if, say, the import is unresolved in lazy mode
1947 // (because the "latest" version of each candidate module either is
1948 // unavailable or does not contain the package), but is resolved in
1949 // eager mode due to a newer-than-latest dependency that is normally
1950 // runed out of the module graph.
1952 // This could also occur if the source code for the module providing the
1953 // package in lazy mode has a checksum error, but eager mode upgrades
1954 // that module to a version with a correct checksum.
1956 // pkg.err should have already been logged elsewhere — along with a
1957 // stack trace — so log only the import path and non-error info here.
1958 suggestUpgrade = true
1959 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)
1961 case pkg.mod != mismatch.mod:
1962 // The package is loaded successfully by both Go versions, but from a
1963 // different module in each. This could lead to subtle (and perhaps even
1964 // unnoticed!) variations in behavior between builds with different
1966 suggestUpgrade = true
1967 ld.errorf("%s loaded from %v,\n\tbut go %s would select %v\n", pkg.stackText(), pkg.mod, ld.TidyCompatibleVersion, mismatch.mod.Version)
1970 base.Fatalf("go: internal error: mismatch recorded for package %s, but no differences found", pkg.path)
1978 // scanDir is like imports.ScanDir but elides known magic imports from the list,
1979 // so that we do not go looking for packages that don't really exist.
1981 // The standard magic import is "C", for cgo.
1983 // The only other known magic imports are appengine and appengine/*.
1984 // These are so old that they predate "go get" and did not use URL-like paths.
1985 // Most code today now uses google.golang.org/appengine instead,
1986 // but not all code has been so updated. When we mostly ignore build tags
1987 // during "go vendor", we look into "// +build appengine" files and
1988 // may see these legacy imports. We drop them so that the module
1989 // search does not look for modules to try to satisfy them.
1990 func scanDir(dir string, tags map[string]bool) (imports_, testImports []string, err error) {
1991 imports_, testImports, err = imports.ScanDir(dir, tags)
1993 filter := func(x []string) []string {
1995 for _, pkg := range x {
1996 if pkg != "C" && pkg != "appengine" && !strings.HasPrefix(pkg, "appengine/") &&
1997 pkg != "appengine_internal" && !strings.HasPrefix(pkg, "appengine_internal/") {
2005 return filter(imports_), filter(testImports), err
2008 // buildStacks computes minimal import stacks for each package,
2009 // for use in error messages. When it completes, packages that
2010 // are part of the original root set have pkg.stack == nil,
2011 // and other packages have pkg.stack pointing at the next
2012 // package up the import stack in their minimal chain.
2013 // As a side effect, buildStacks also constructs ld.pkgs,
2014 // the list of all packages loaded.
2015 func (ld *loader) buildStacks() {
2016 if len(ld.pkgs) > 0 {
2017 panic("buildStacks")
2019 for _, pkg := range ld.roots {
2020 pkg.stack = pkg // sentinel to avoid processing in next loop
2021 ld.pkgs = append(ld.pkgs, pkg)
2023 for i := 0; i < len(ld.pkgs); i++ { // not range: appending to ld.pkgs in loop
2025 for _, next := range pkg.imports {
2026 if next.stack == nil {
2028 ld.pkgs = append(ld.pkgs, next)
2031 if next := pkg.test; next != nil && next.stack == nil {
2033 ld.pkgs = append(ld.pkgs, next)
2036 for _, pkg := range ld.roots {
2041 // stackText builds the import stack text to use when
2042 // reporting an error in pkg. It has the general form
2047 // other2.test imports
2050 func (pkg *loadPkg) stackText() string {
2051 var stack []*loadPkg
2052 for p := pkg; p != nil; p = p.stack {
2053 stack = append(stack, p)
2056 var buf bytes.Buffer
2057 for i := len(stack) - 1; i >= 0; i-- {
2059 fmt.Fprint(&buf, p.path)
2060 if p.testOf != nil {
2061 fmt.Fprint(&buf, ".test")
2064 if stack[i-1].testOf == p {
2065 fmt.Fprint(&buf, " tested by\n\t")
2067 fmt.Fprint(&buf, " imports\n\t")
2074 // why returns the text to use in "go mod why" output about the given package.
2075 // It is less ornate than the stackText but contains the same information.
2076 func (pkg *loadPkg) why() string {
2077 var buf strings.Builder
2078 var stack []*loadPkg
2079 for p := pkg; p != nil; p = p.stack {
2080 stack = append(stack, p)
2083 for i := len(stack) - 1; i >= 0; i-- {
2085 if p.testOf != nil {
2086 fmt.Fprintf(&buf, "%s.test\n", p.testOf.path)
2088 fmt.Fprintf(&buf, "%s\n", p.path)
2094 // Why returns the "go mod why" output stanza for the given package,
2095 // without the leading # comment.
2096 // The package graph must have been loaded already, usually by LoadPackages.
2097 // If there is no reason for the package to be in the current build,
2098 // Why returns an empty string.
2099 func Why(path string) string {
2100 pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
2107 // WhyDepth returns the number of steps in the Why listing.
2108 // If there is no reason for the package to be in the current build,
2109 // WhyDepth returns 0.
2110 func WhyDepth(path string) int {
2112 pkg, _ := loaded.pkgCache.Get(path).(*loadPkg)
2113 for p := pkg; p != nil; p = p.stack {