all: replace magic 0x80 with named constant utf8.RuneSelf

Change-Id: Id1c2e8e9d60588de866e8b6ca59cc83dd28f848f
Reviewed-on: https://go-review.googlesource.com/21756
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/bufio/bufio.go

@@ -266,7 +266,7 @@ func (b *Reader) ReadRune() (r rune, size int, err error) {
 		return 0, 0, b.readErr()
 	}
 	r, size = rune(b.buf[b.r]), 1
-	if r >= 0x80 {
+	if r >= utf8.RuneSelf {
 		r, size = utf8.DecodeRune(b.buf[b.r:b.w])
 	}
 	b.r += size

src/cmd/compile/internal/gc/fmt.go

@@ -337,7 +337,7 @@ func Vconv(v Val, flag FmtFlag) string {
 
 	case CTRUNE:
 		x := v.U.(*Mpint).Int64()
-		if ' ' <= x && x < 0x80 && x != '\\' && x != '\'' {
+		if ' ' <= x && x < utf8.RuneSelf && x != '\\' && x != '\'' {
 			return fmt.Sprintf("'%c'", int(x))
 		}
 		if 0 <= x && x < 1<<16 {

src/encoding/asn1/asn1.go

@@ -393,7 +393,7 @@ func isPrintable(b byte) bool {
 // byte slice and returns it.
 func parseIA5String(bytes []byte) (ret string, err error) {
 	for _, b := range bytes {
-		if b >= 0x80 {
+		if b >= utf8.RuneSelf {
 			err = SyntaxError{"IA5String contains invalid character"}
 			return
 		}

src/go/build/build.go

@@ -1266,7 +1266,7 @@ func safeCgoName(s string, spaces bool) bool {
 		safe = safe[len(safeSpaces):]
 	}
 	for i := 0; i < len(s); i++ {
-		if c := s[i]; c < 0x80 && bytes.IndexByte(safe, c) < 0 {
+		if c := s[i]; c < utf8.RuneSelf && bytes.IndexByte(safe, c) < 0 {
 			return false
 		}
 	}

src/go/build/read.go

@@ -8,6 +8,7 @@ import (
 	"bufio"
 	"errors"
 	"io"
+	"unicode/utf8"
 )
 
 type importReader struct {
@@ -20,7 +21,7 @@ type importReader struct {
 }
 
 func isIdent(c byte) bool {
-	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '_' || c >= 0x80
+	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '_' || c >= utf8.RuneSelf
 }
 
 var (

src/go/scanner/scanner.go

@@ -64,7 +64,7 @@ func (s *Scanner) next() {
 		switch {
 		case r == 0:
 			s.error(s.offset, "illegal character NUL")
-		case r >= 0x80:
+		case r >= utf8.RuneSelf:
 			// not ASCII
 			r, w = utf8.DecodeRune(s.src[s.rdOffset:])
 			if r == utf8.RuneError && w == 1 {
@@ -255,11 +255,11 @@ func (s *Scanner) findLineEnd() bool {
 }
 
 func isLetter(ch rune) bool {
-	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 0x80 && unicode.IsLetter(ch)
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
 }
 
 func isDigit(ch rune) bool {
-	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
+	return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
 }
 
 func (s *Scanner) scanIdentifier() string {

src/html/template/css.go

@@ -243,7 +243,7 @@ func cssValueFilter(args ...interface{}) string {
 				return filterFailsafe
 			}
 		default:
-			if c < 0x80 && isCSSNmchar(rune(c)) {
+			if c < utf8.RuneSelf && isCSSNmchar(rune(c)) {
 				id = append(id, c)
 			}
 		}

src/net/http/cookiejar/punycode.go

@@ -37,7 +37,7 @@ func encode(prefix, s string) (string, error) {
 	delta, n, bias := int32(0), initialN, initialBias
 	b, remaining := int32(0), int32(0)
 	for _, r := range s {
-		if r < 0x80 {
+		if r < utf8.RuneSelf {
 			b++
 			output = append(output, byte(r))
 		} else {