// The zero Value corresponds to nil.
type Value struct {
	_ [0]func() // disallow ==
	// num holds the value for Kinds Int64, Uint64, Float64, Bool and Duration,
	// the string length for KindString, and nanoseconds since the epoch for KindTime.
	num uint64
	// If any is of type Kind, then the value is in num as described above.
	// If any is of type *time.Location, then the Kind is Time and time.Time value

	case *Slice, *Signature, *Map:
		return check.kindString(typ) + " can only be compared to nil"
	}
	// see if we can extract a more specific error
	var cause string
	comparable(typ, true, nil, func(format string, args ...interface{}) {
		cause = check.sprintf(format, args...)
	})
	return cause
}

// kindString returns the type kind as a string.
func (check *Checker) kindString(typ Type) string {
	switch under(typ).(type) {

	case *Slice, *Signature, *Map:
		return check.kindString(typ) + " can only be compared to nil"
	}
	// see if we can extract a more specific error
	var cause string
	comparable(typ, true, nil, func(format string, args ...interface{}) {
		cause = check.sprintf(format, args...)
	})
	return cause
}

// kindString returns the type kind as a string.
func (check *Checker) kindString(typ Type) string {
	switch under(typ).(type) {

		arg := list[i]
		if disallow != nil && disallow.FindString(arg) == arg {
			goto Bad
		}
		if allow != nil && allow.FindString(arg) == arg {
			continue Args
		}
		for _, re := range invalid {
			if re.FindString(arg) == arg { // must be complete match
				goto Bad
			}
		}
		for _, re := range valid {
			if re.FindString(arg) == arg { // must be complete match
				continue Args
			}
		}

	for _, featureText := range utilfeature.DefaultFeatureGate.KnownFeatures() {
		// we have to parse this from KnownFeatures, because usage of mutable FeatureGate is not allowed in unit tests
		feature := featureGateRegex.FindString(featureText)
		if strings.Contains(featureText, string(featuregate.Alpha)) && feature != "AllAlpha" {
			alphaFeatures.Insert(feature)
		}

	}

	for name, controller := range NewControllerDescriptors() {

	{"32M", 32 << 20},
}

func TestLongest(t *testing.T) {
	re, err := Compile(`a(|b)`)
	if err != nil {
		t.Fatal(err)
	}
	if g, w := re.FindString("ab"), "a"; g != w {
		t.Errorf("first match was %q, want %q", g, w)
	}
	re.Longest()
	if g, w := re.FindString("ab"), "ab"; g != w {
		t.Errorf("longest match was %q, want %q", g, w)
	}
}

// TestProgramTooLongForBacktrack tests that a regex which is too long

	b.StopTimer()
	re := MustCompile("a+b+")
	wantSubs := "aaabb"
	s := "acbb" + wantSubs + "dd"
	b.StartTimer()
	b.ReportAllocs()
	for i := 0; i < b.N; i++ {
		subs := re.FindString(s)
		if subs != wantSubs {
			b.Fatalf("FindString(%q) = %q; want %q", s, subs, wantSubs)
		}
	}
}

func BenchmarkFindSubmatch(b *testing.B) {
	b.StopTimer()
	re := MustCompile("a(a+b+)b")
	wantSubs := "aaabb"

// A return value of nil indicates no match.
func (re *Regexp) FindIndex(b []byte) (loc []int) {
	a := re.doExecute(nil, b, "", 0, 2, nil)
	if a == nil {
		return nil
	}
	return a[0:2]
}

// FindString returns a string holding the text of the leftmost match in s of the regular
// expression. If there is no match, the return value is an empty string,
// but it will also be empty if the regular expression successfully matches

		{"KindBool", Const, 21},
		{"KindDuration", Const, 21},
		{"KindFloat64", Const, 21},
		{"KindGroup", Const, 21},
		{"KindInt64", Const, 21},
		{"KindLogValuer", Const, 21},
		{"KindString", Const, 21},
		{"KindTime", Const, 21},
		{"KindUint64", Const, 21},
		{"Level", Type, 21},
		{"LevelDebug", Const, 21},
		{"LevelError", Const, 21},
		{"LevelInfo", Const, 21},

# Our build tools, post jammy, breaks old versions of docker.
# These old versions are surprisingly common, so build in a check here
define warning
Docker version is too old, please upgrade to a newer version.
endef
ifneq ($(findstring google,$(HOSTNAME)),)
warning+=Googlers: go/installdocker\#the-version-of-docker-thats-installed-is-old-eg-1126
endif
# The old docker issue manifests as not being able to run *any* binary. So we can test