[dev.inline] cmd/compile/internal/syntax: remove gcCompat uses in scanner

- make the scanner unconditionally gc compatible
- consistently use "invalid" instead "illegal" in errors

Reviewed in and cherry-picked from https://go-review.googlesource.com/#/c/33896/.

Change-Id: I4c4253e7392f3311b0d838bbe503576c9469b203
Reviewed-on: https://go-review.googlesource.com/34237
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/syntax/parser.go

@@ -53,7 +53,6 @@ func (p *parser) init(filename string, src io.Reader, errh ErrorHandler, pragh P
 				p.pragma |= pragh(p.pos_at(line, col), text)
 			}
 		},
-		gcCompat,
 	)
 
 	p.first = nil

src/cmd/compile/internal/syntax/scanner.go

@@ -21,9 +21,8 @@ import (
 
 type scanner struct {
 	source
-	pragh    func(line, col uint, msg string)
-	gcCompat bool // TODO(gri) remove this eventually (only here so we can build w/o parser)
-	nlsemi   bool // if set '\n' and EOF translate to ';'
+	pragh  func(line, col uint, msg string)
+	nlsemi bool // if set '\n' and EOF translate to ';'
 
 	// current token, valid after calling next()
 	line, col uint
@@ -34,10 +33,9 @@ type scanner struct {
 	prec      int      // valid if tok is _Operator, _AssignOp, or _IncOp
 }
 
-func (s *scanner) init(src io.Reader, errh, pragh func(line, col uint, msg string), gcCompat bool) {
+func (s *scanner) init(src io.Reader, errh, pragh func(line, col uint, msg string)) {
 	s.source.init(src, errh)
 	s.pragh = pragh
-	s.gcCompat = gcCompat
 	s.nlsemi = false
 }
 
@@ -67,7 +65,7 @@ redo:
 	// token start
 	s.line, s.col = s.source.line0, s.source.col0
 
-	if isLetter(c) || c >= utf8.RuneSelf && (unicode.IsLetter(c) || s.isCompatRune(c, true)) {
+	if isLetter(c) || c >= utf8.RuneSelf && s.isIdentRune(c, true) {
 		s.ident()
 		return
 	}
@@ -290,7 +288,7 @@ redo:
 
 	default:
 		s.tok = 0
-		s.error(fmt.Sprintf("illegal character %#U", c))
+		s.error(fmt.Sprintf("invalid character %#U", c))
 		goto redo
 	}
 
@@ -324,7 +322,7 @@ func (s *scanner) ident() {
 
 	// general case
 	if c >= utf8.RuneSelf {
-		for unicode.IsLetter(c) || c == '_' || unicode.IsDigit(c) || s.isCompatRune(c, false) {
+		for s.isIdentRune(c, false) {
 			c = s.getr()
 		}
 	}
@@ -346,14 +344,18 @@ func (s *scanner) ident() {
 	s.tok = _Name
 }
 
-func (s *scanner) isCompatRune(c rune, start bool) bool {
-	if !s.gcCompat || c < utf8.RuneSelf {
-		return false
-	}
-	if start && unicode.IsNumber(c) {
-		s.error(fmt.Sprintf("identifier cannot begin with digit %#U", c))
-	} else {
+func (s *scanner) isIdentRune(c rune, first bool) bool {
+	switch {
+	case unicode.IsLetter(c) || c == '_':
+		// ok
+	case unicode.IsDigit(c):
+		if first {
+			s.error(fmt.Sprintf("identifier cannot begin with digit %#U", c))
+		}
+	case c >= utf8.RuneSelf:
 		s.error(fmt.Sprintf("invalid identifier character %#U", c))
+	default:
+		return false
 	}
 	return true
 }
@@ -643,19 +645,11 @@ func (s *scanner) escape(quote rune) bool {
 			if c < 0 {
 				return true // complain in caller about EOF
 			}
-			if s.gcCompat {
-				name := "hex"
-				if base == 8 {
-					name = "octal"
-				}
-				s.error(fmt.Sprintf("non-%s character in escape sequence: %c", name, c))
-			} else {
-				if c != quote {
-					s.error(fmt.Sprintf("illegal character %#U in escape sequence", c))
-				} else {
-					s.error("escape sequence incomplete")
-				}
+			kind := "hex"
+			if base == 8 {
+				kind = "octal"
 			}
+			s.error(fmt.Sprintf("non-%s character in escape sequence: %c", kind, c))
 			s.ungetr()
 			return false
 		}

src/cmd/compile/internal/syntax/scanner_test.go

@@ -22,7 +22,7 @@ func TestScanner(t *testing.T) {
 	defer src.Close()
 
 	var s scanner
-	s.init(src, nil, nil, false)
+	s.init(src, nil, nil)
 	for {
 		s.next()
 		if s.tok == _EOF {
@@ -51,7 +51,7 @@ func TestTokens(t *testing.T) {
 
 	// scan source
 	var got scanner
-	got.init(&bytesReader{buf}, nil, nil, false)
+	got.init(&bytesReader{buf}, nil, nil)
 	got.next()
 	for i, want := range sampleTokens {
 		nlsemi := false
@@ -269,7 +269,7 @@ func TestScanErrors(t *testing.T) {
 
 		// token-level errors
 		{"x + ~y", "bitwise complement operator is ^", 1, 5},
-		{"foo$bar = 0", "illegal character U+0024 '$'", 1, 4},
+		{"foo$bar = 0", "invalid character U+0024 '$'", 1, 4},
 		{"const x = 0xyz", "malformed hex constant", 1, 13},
 		{"0123456789", "malformed octal constant", 1, 11},
 		{"0123456789. /* foobar", "comment not terminated", 1, 13},   // valid float constant
@@ -348,7 +348,7 @@ func TestScanErrors(t *testing.T) {
 				// TODO(gri) make this use position info
 				t.Errorf("%q: got unexpected %q at line = %d", test.src, msg, line)
 			}
-		}, nil, true)
+		}, nil)
 
 		for {
 			s.next()

test/fixedbugs/issue11610.go

@@ -9,7 +9,7 @@
 
 package a
 import""  // ERROR "import path is empty"
-var?      // ERROR "illegal character U\+003F '\?'"
+var?      // ERROR "invalid character U\+003F '\?'"
 
 var x int // ERROR "unexpected var"