//  2. parse the nocallback and noescape directives.
func (f *File) ProcessCgoDirectives() {
	linesIn := strings.Split(f.Preamble, "\n")
	linesOut := make([]string, 0, len(linesIn))
	f.NoCallbacks = make(map[string]bool)
	f.NoEscapes = make(map[string]bool)
	for _, line := range linesIn {
		l := strings.TrimSpace(line)
		if len(l) < 5 || l[:4] != "#cgo" || !unicode.IsSpace(rune(l[4])) {