go/scanner: clear all fields after Scanner reuse

We were missing s.nlPos = token.NoPos in Init, but while we are here
let's make it less likely to hit this it in future.

Change-Id: Ief4c0ba2cf97bc556d901eabc8e172406a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/738680
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

diff --git a/src/go/scanner/scanner.go b/src/go/scanner/scanner.go
index 07d987c88f9bab3bf9b3514d829345aff39402bf..f8610640c055482e703a3b1dc9dbd326dd9994d6 100644 (file)
--- a/src/go/scanner/scanner.go
+++ b/src/go/scanner/scanner.go
@@ -144,18 +144,18 @@ func (s *Scanner) Init(file *token.File, src []byte, err ErrorHandler, mode Mode
        if file.Size() != len(src) {
                panic(fmt.Sprintf("file size (%d) does not match src len (%d)", file.Size(), len(src)))
        }
-       s.file = file
-       s.dir, _ = filepath.Split(file.Name())
-       s.src = src
-       s.err = err
-       s.mode = mode
-
-       s.ch = ' '
-       s.offset = 0
-       s.rdOffset = 0
-       s.lineOffset = 0
-       s.insertSemi = false
-       s.ErrorCount = 0
+
+       dir, _ := filepath.Split(file.Name())
+
+       *s = Scanner{
+               file: file,
+               dir:  dir,
+               src:  src,
+               err:  err,
+               mode: mode,
+
+               ch: ' ',
+       }
 
        s.next()
        if s.ch == bom {

diff --git a/src/go/scanner/scanner_test.go b/src/go/scanner/scanner_test.go
index 98036bea4e0969cd2ffac57487bd0144b8257a7c..ae2cc633923d5b6f23f536f6dbc5411aa164339c 100644 (file)
--- a/src/go/scanner/scanner_test.go
+++ b/src/go/scanner/scanner_test.go
@@ -1153,3 +1153,29 @@ func TestNumbers(t *testing.T) {
                }
        }
 }
+
+func TestScanReuseSemiInNewlineComment(t *testing.T) {
+       fset := token.NewFileSet()
+
+       const src = "identifier /*a\nb*/ + other"
+       var s Scanner
+       s.Init(fset.AddFile("test.go", -1, len(src)), []byte(src), func(pos token.Position, msg string) {
+               t.Fatal(msg)
+       }, ScanComments)
+
+       s.Scan() // IDENT(identifier)
+
+       _, tok, _ := s.Scan() // COMMENT(/*a\nb*/)
+       if tok != token.COMMENT {
+               t.Fatalf("tok = %v; want = token.SEMICOLON", tok)
+       }
+
+       s.Init(fset.AddFile("test.go", -1, len(src)), []byte(src), func(pos token.Position, msg string) {
+               t.Fatal(msg)
+       }, ScanComments)
+
+       _, tok, _ = s.Scan()
+       if tok != token.IDENT {
+               t.Fatalf("tok = %v; want = token.IDENT", tok)
+       }
+}