errors = append(errors, re)
				continue
			}

			if _, frag, ok := bytes.Cut(line, []byte("ERROR HERE: ")); ok {
				re, err := regexp.Compile(fmt.Sprintf(":%d:.*%s", i+1, frag))
				if err != nil {
					t.Errorf("Invalid regexp after `ERROR HERE: `: %#q", frag)
					continue
				}
				errors = append(errors, re)
			}

			if _, frag, ok := bytes.Cut(line, []byte("ERROR MESSAGE: ")); ok {

func crawl(url string, sourceURL string) {
	if strings.Contains(url, "/devel/release") {
		return
	}
	mu.Lock()
	defer mu.Unlock()
	if u, frag, ok := strings.Cut(url, "#"); ok {
		url = u
		if frag != "" {
			uf := urlFrag{url, frag}
			neededFrags[uf] = append(neededFrags[uf], sourceURL)
		}
	}
	if crawled[url] {
		return
	}
	crawled[url] = true

	wg.Add(1)
	go func() {

import (
	"testing"
)

func TestURLNormalizer(t *testing.T) {
	tests := []struct {
		url, want string
	}{
		{"", ""},
		{
			"http://example.com:80/foo/bar?q=foo%20&bar=x+y#frag",
			"http://example.com:80/foo/bar?q=foo%20&bar=x+y#frag",
		},
		{" ", "%20"},
		{"%7c", "%7c"},
		{"%7C", "%7C"},
		{"%2", "%252"},
		{"%", "%25"},
		{"%z", "%25z"},
		{"/foo|bar/%5c\u1234", "/foo%7cbar/%5c%e1%88%b4"},
	}

// set is already open.
func isLocked(err error) bool {
	s := err.Error()

	for _, frag := range lockedErrStrings {
		if strings.Contains(s, frag) {
			return true
		}
	}

	return false
}

func openFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
	// Plan 9 uses a mode bit instead of explicit lock/unlock syscalls.
	//

	// ^ in "^http://auth/path?k=v#frag".
	urlPartNone urlPart = iota
	// urlPartPreQuery occurs in the scheme, authority, or path; between the
	// ^s in "h^ttp://auth/path^?k=v#frag".
	urlPartPreQuery
	// urlPartQueryOrFrag occurs in the query portion between the ^s in
	// "http://auth/path?^k=v#frag^".
	urlPartQueryOrFrag

	var frag []byte
	// Use ReadSlice to look for delim, accumulating full buffers.
	for {
		var e error
		frag, e = b.ReadSlice(delim)
		if e == nil { // got final fragment
			break
		}
		if e != ErrBufferFull { // unexpected error
			err = e
			break
		}

		// Make a copy of the buffer.
		buf := bytes.Clone(frag)
		fullBuffers = append(fullBuffers, buf)

	args := make([]string, 0, len(rawArgs))
	for i, frags := range rawArgs {
		isRegexp := false
		for _, j := range regexpArgs {
			if i == j {
				isRegexp = true
				break
			}
		}

		var b strings.Builder
		for _, frag := range frags {
			if frag.quoted {
				b.WriteString(frag.s)
			} else {
				b.WriteString(s.ExpandEnv(frag.s, isRegexp))
			}
		}
		args = append(args, b.String())

		return
	}
	defer d.Close()
	list2 = nil
	for {
		n := 1
		if len(list2) > 0 {
			n = 2
		}
		frag, err := d.ReadDir(n)
		if len(frag) > n {
			t.errorf("%s: third Open: ReadDir(%d) after %d: %d entries (too many)", dir, n, len(list2), len(frag))
			return
		}
		list2 = append(list2, frag...)
		if err == io.EOF {
			break
		}
		if err != nil {

	{"http:opaque?x=y#zzz", "https:/foo?a=b#frag", "https:/foo?a=b#frag"},
	{"http:opaque?x=y#zzz", "https:foo:bar", "https:foo:bar"},
	{"http:opaque?x=y#zzz", "https:bar/baz?a=b#frag", "https:bar/baz?a=b#frag"},
	{"http:opaque?x=y#zzz", "https://user@host:1234?a=b#frag", "https://user@host:1234?a=b#frag"},
	{"http:opaque?x=y#zzz", "?a=b#frag", "http:opaque?a=b#frag"},
}

func TestResolveReference(t *testing.T) {

// error, due to parsing ambiguities.
func Parse(rawURL string) (*URL, error) {
	// Cut off #frag
	u, frag, _ := strings.Cut(rawURL, "#")
	url, err := parse(u, false)
	if err != nil {
		return nil, &Error{"parse", u, err}
	}
	if frag == "" {
		return url, nil
	}
	if err = url.setFragment(frag); err != nil {
		return nil, &Error{"parse", rawURL, err}
	}
	return url, nil
}