func main()

in scripts/genmod/main.go [46:110]
60 lines of code
17 McCabe index (conditional complexity)

func main() {
	flag.Parse()
	if flag.NArg() != 1 {
		flag.Usage()
		os.Exit(2)
	}

	// Locate and parse all go.mod files.
	root, err := filepath.Abs(flag.Arg(0))
	if err != nil {
		log.Fatal(err)
	}
	if resolved, err := os.Readlink(root); err == nil {
		root = resolved
	}

	paths := strings.Split(*excludedPaths, ",")

	modules := make(map[string]*GoMod) // by module path
	if err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		for _, p := range paths {
			dir := strings.TrimPrefix(path, root+"/")
			if dir == p {
				fmt.Fprintf(os.Stderr, "skipping %s\n", dir)
				return filepath.SkipDir
			}
		}
		if !info.IsDir() {
			if info.Name() == "go.mod" {
				gomod, err := readGoMod(path)
				if err != nil {
					return err
				}
				modules[gomod.Module.Path] = gomod
			}
			return nil
		}
		if name := info.Name(); name != root && strings.HasPrefix(name, ".") {
			return filepath.SkipDir
		}
		return nil
	}); err != nil {
		log.Fatal(err)
	}

	seen := make(map[string]bool)
	var modulePaths []string
	for path := range modules {
		toposort(path, modules, seen, &modulePaths)
	}
	for _, modpath := range modulePaths {
		gomod := modules[modpath]
		absdir, err := filepath.Abs(gomod.dir)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Fprintf(os.Stderr, "# updating %s\n", gomod.Module.Path)
		if err := updateModule(absdir, gomod, modules); err != nil {
			log.Fatal(err)
		}
	}
}