all: clean up old Go hacks

We are not maintaining pre-Go 1.24 code anymore,
and certainly not pre-Go 1.16 or pre-Go 1.9 code.

Change-Id: Idd3a1fd476f8eb34b8fbb6352addb5955e6b5893
Reviewed-on: https://go-review.googlesource.com/c/text/+/738582
Auto-Submit: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>

Author: rsc

internal/export/idna/idna.go

@@ -857,3 +857,24 @@ func ascii(s string) bool {
 	}
 	return true
 }
+
+// appendMapping appends the mapping for the respective rune. isMapped must be
+// true. A mapping is a categorization of a rune as defined in UTS #46.
+func (c info) appendMapping(b []byte, s string) []byte {
+	index := int(c >> indexShift)
+	if c&xorBit == 0 {
+		p := index
+		return append(b, mappings[mappingIndex[p]:mappingIndex[p+1]]...)
+	}
+	b = append(b, s...)
+	if c&inlineXOR == inlineXOR {
+		// TODO: support and handle two-byte inline masks
+		b[len(b)-1] ^= byte(index)
+	} else {
+		for p := len(b) - int(xorData[index]); p < len(b); p++ {
+			index++
+			b[p] ^= xorData[index]
+		}
+	}
+	return b
+}

internal/export/idna/trie13.0.0.go

@@ -333,7 +333,7 @@ func String(name string) Message {
 //
 // The name passed to a Var must be unique within message sequence.
 func Var(name string, msg ...Message) Message {
-	return &catmsg.Var{Name: name, Message: firstInSequence(msg)}
+	return &catmsg.Var{Name: name, Message: catmsg.FirstOf(msg)}
 }
 
 // Context returns a Context for formatting messages.

message/catalog/catalog.go

@@ -205,7 +205,7 @@ func initCatalog(t *testing.T, tc testCase) Catalog {
 		case Message:
 			msg = x
 		case []Message:
-			msg = firstInSequence(x)
+			msg = catmsg.FirstOf(x)
 		}
 		data, _ := catmsg.Compile(language.MustParse(e.tag), nil, msg)
 		m[e.tag].(dictionary)[e.key] = data

message/catalog/catalog_test.go

@@ -12,6 +12,10 @@ import (
 	"golang.org/x/text/language"
 )
 
+// A Message holds a collection of translations for the same phrase that may
+// vary based on the values of substitution arguments.
+type Message = catmsg.Message
+
 // TODO:
 // Dictionary returns a Dictionary that returns the first Message, using the
 // given language tag, that matches:
@@ -38,7 +42,7 @@ func (b *Builder) lookup(tag language.Tag, key string) (data string, ok bool) {
 }
 
 func (c *Builder) set(tag language.Tag, key string, s *store, msg ...Message) error {
-	data, err := catmsg.Compile(tag, &dict{&c.macros, tag}, firstInSequence(msg))
+	data, err := catmsg.Compile(tag, &dict{&c.macros, tag}, catmsg.FirstOf(msg))
 
 	s.mutex.Lock()
 	defer s.mutex.Unlock()

message/catalog/dict.go

@@ -25,9 +25,6 @@ import (
 
 var genFiles = flag.Bool("gen", false, "generate output files instead of comparing")
 
-// setHelper is testing.T.Helper on Go 1.9+, overridden by go19_test.go.
-var setHelper = func(t *testing.T) {}
-
 func TestFullCycle(t *testing.T) {
 	if runtime.GOOS == "android" {
 		t.Skip("cannot load outside packages on android")
@@ -75,7 +72,7 @@ func TestFullCycle(t *testing.T) {
 		}
 		t.Run(f.Name(), func(t *testing.T) {
 			chk := func(t *testing.T, err error) {
-				setHelper(t)
+				t.Helper()
 				if err != nil {
 					t.Fatal(err)
 				}

message/catalog/go19.go

@@ -334,3 +334,7 @@ func (t *Transformer) advanceString(s string) (n int, ok bool) {
 	}
 	return n, true
 }
+
+func (t *Transformer) isFinal() bool {
+	return t.state == ruleLTRFinal || t.state == ruleRTLFinal || t.state == ruleInitial
+}