}

// readVendorList reads the list of vendored modules from vendor/modules.txt.
func readVendorList(vendorDir string) {
	vendorOnce.Do(func() {
		vendorList = nil
		vendorPkgModule = make(map[string]module.Version)
		vendorVersion = make(map[string]string)
		vendorMeta = make(map[module.Version]vendorMetadata)
		vendorFile := filepath.Join(vendorDir, "modules.txt")
		data, err := os.ReadFile(vendorFile)
		if err != nil {

					dirs = append(dirs, dir)
					roots = append(roots, modRoot)
				}
			}
		}

		if HasModRoot() {
			vendorDir := VendorDir()
			dir, inVendorDir, _ := dirInModule(path, "", vendorDir, false)
			if inVendorDir {
				readVendorList(vendorDir)
				// If vendorPkgModule does not contain an entry for path then it's probably either because

			if modRoot := MainModules.ModRoot(mod); modRoot != "" {
				walkPkgs(modRoot, MainModules.PathPrefix(mod), pruneGoMod|pruneVendor)
			}
		}
		if HasModRoot() {
			walkPkgs(VendorDir(), "", pruneVendor)
		}
		return
	}

	for _, mod := range modules {
		if gover.IsToolchain(mod.Path) || !treeCanMatch(mod.Path) {
			continue
		}

		var (
			root, modPrefix string

				goVersion = index.goVersion
			}
		}
		vendorDir := ""
		if workFilePath != "" {
			vendorDir = filepath.Join(filepath.Dir(workFilePath), "vendor")
		} else {
			if len(modRoots) != 1 {
				panic(fmt.Errorf("outside workspace mode, but have %v modRoots", modRoots))
			}
			vendorDir = filepath.Join(modRoots[0], "vendor")
		}
		if fi, err := fsys.Stat(vendorDir); err == nil && fi.IsDir() {
			if goVersion != "" {

	var vdir string
	switch {
	case filepath.IsAbs(vendorO):
		vdir = vendorO
	case vendorO != "":
		vdir = filepath.Join(base.Cwd(), vendorO)
	default:
		vdir = filepath.Join(modload.VendorDir())
	}
	if err := os.RemoveAll(vdir); err != nil {
		base.Fatal(err)
	}

	modpkgs := make(map[module.Version][]string)
	for _, pkg := range pkgs {
		m := modload.PackageModule(pkg)

	}
	if gover.IsToolchain(m.Path) {
		return rawGoModSummary(m)
	}

	if cfg.BuildMod == "vendor" {
		summary := &modFileSummary{
			module: module.Version{Path: m.Path},
		}

		readVendorList(VendorDir())
		if vendorVersion[m.Path] != m.Version {
			// This module is not vendored, so packages cannot be loaded from it and
			// it cannot be relevant to the build.
			return summary, nil
		}

			if pkg, found := strings.CutPrefix(suffix, "vendor/"); found {
				if cfg.BuildMod != "vendor" {
					return "", fmt.Errorf("without -mod=vendor, directory %s has no package path", absDir)
				}

				readVendorList(VendorDir())
				if _, ok := vendorPkgModule[pkg]; !ok {
					return "", fmt.Errorf("directory %s is not a package listed in vendor/modules.txt", absDir)
				}
				return pkg, nil
			}

					toPath = "GOPATH"
				}
			} else if m.Dir == "" {
				// The module is in the vendor directory. Replace the entire vendor
				// directory path, because the module's Dir is not filled in.
				from = modload.VendorDir()
				toPath = "vendor"
			} else {
				from = m.Dir
				toPath = m.Path
				if m.Version != "" {
					toPath += "@" + m.Version
				}
			}