// during -fix).  Even so, we need to make sure the version is a valid token.
func allowedVersionArg(arg string) bool {
	return !modfile.MustQuote(arg)
}

// parsePathVersionOptional parses path[@version], using adj to
// describe any errors.
func parsePathVersionOptional(adj, arg string, allowDirPath bool) (path, version string, err error) {
	before, after, found := strings.Cut(arg, "@")
	if !found {
		path = arg
	} else {

	path = arg
	if err := module.CheckImportPath(path); err != nil {
		base.Fatalf("go: -%s=%s: invalid path: %v", flag, arg, err)
	}
	return path
}

// parsePathVersionOptional parses path[@version], using adj to
// describe any errors.
func parsePathVersionOptional(adj, arg string, allowDirPath bool) (path, version string, err error) {
	if allowDirPath && modfile.IsDirectoryPath(arg) {
		return arg, "", nil
	}