// pieces supplied behind-the-scenes by package runtime.
	extFiles := len(p.CgoFiles) + len(p.CFiles) + len(p.CXXFiles) + len(p.MFiles) + len(p.FFiles) + len(p.SFiles) + len(p.SysoFiles) + len(p.SwigFiles) + len(p.SwigCXXFiles)
	if p.Standard {
		switch p.ImportPath {
		case "bytes", "internal/poll", "net", "os":
			fallthrough
		case "runtime/metrics", "runtime/pprof", "runtime/trace":
			fallthrough

		return &p.FFiles
	case ".s", ".S", ".sx":
		return &p.SFiles
	case ".swig":
		return &p.SwigFiles
	case ".swigcxx":
		return &p.SwigCXXFiles
	case ".syso":
		return &p.SysoFiles
	}
	return nil
}

var errNoModules = errors.New("not using modules")

func findImportComment(data []byte) (s string, line int) {
	// expect keyword package
	word, data := parseWord(data)

        SFiles            []string   // .s source files
        SwigFiles         []string   // .swig files
        SwigCXXFiles      []string   // .swigcxx files
        SysoFiles         []string   // .syso object files to add to archive
        TestGoFiles       []string   // _test.go files in package
        XTestGoFiles      []string   // _test.go files outside package

        // Embedded files