hist   []Dir    // History of reported Dirs.
	offset int      // Counter for Next.
}

var dirs Dirs

// dirsInit starts the scanning of package directories in GOROOT and GOPATH. Any
// extra paths passed to it are included in the channel.
func dirsInit(extra ...Dir) {
	if buildCtx.GOROOT == "" {
		stdout, err := exec.Command("go", "env", "GOROOT").Output()
		if err != nil {

	buildCtx.GOPATH = ""
	testGOPATH = true // force GOPATH mode; module test is in cmd/go/testdata/script/mod_doc.txt

	// Set GOROOT in case runtime.GOROOT is wrong (for example, if the test was
	// built with -trimpath). dirsInit would identify it using 'go env GOROOT',
	// but we can't be sure that the 'go' in $PATH is the right one either.
	buildCtx.GOROOT = testenv.GOROOT(nil)
	build.Default.GOROOT = testenv.GOROOT(nil)

	fmt.Fprintf(os.Stderr, "\tgo help doc\n\n")
	fmt.Fprintf(os.Stderr, "Flags:\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("doc: ")
	telemetry.Start()
	dirsInit()
	err := do(os.Stdout, flag.CommandLine, os.Args[1:])
	if err != nil {
		log.Fatal(err)
	}
}

// do is the workhorse, broken out of main to make testing easier.