code review 4572049: go/scanner: partially revert CL4538096 now that we have...

src/pkg/go/scanner/scanner.go

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Package scanner implements a scanner for Go source text. Takes a []byte as
 // source which can then be tokenized through repeated calls to the Scan
 // function. Typical use:
 //
 //      var s Scanner
 //      fset := token.NewFileSet()  // position information is relative to fset
 //      file := fset.AddFile(filename, fset.Base(), len(src))  // register file
 //      s.Init(file, src, nil /* no error handler */, 0)
 //      for {
 //              pos, tok, lit := s.Scan()
 //              if tok == token.EOF {
 //                      break
 //              }
 //              // do something here with pos, tok, and lit
 //      }
 //
 package scanner
 
 import (
         "bytes"
+        "fmt"
         "go/token"
         "path/filepath"
         "strconv"
         "unicode"
         "utf8"
 )
 
 
 // A Scanner holds the scanner's internal state while processing
 // a given text.  It can be allocated as part of another data
@@ skipping 632 matching lines @@
                         if S.ch == '^' {
                                 S.next()
                                 tok = S.switch2(token.AND_NOT, token.AND_NOT_ASSIGN)
                         } else {
                                 tok = S.switch3(token.AND, token.AND_ASSIGN, '&', token.LAND)
                         }
                 case '|':
                         tok = S.switch3(token.OR, token.OR_ASSIGN, '|', token.LOR)
                 default:
                         if S.mode&AllowIllegalChars == 0 {
-                                S.error(offs, "illegal character "+strconv.QuoteRune(ch))
+                                S.error(offs, fmt.Sprintf("illegal character %#U", ch))
                         }
                         insertSemi = S.insertSemi // preserve insertSemi info
                 }
         }
 
         if S.mode&InsertSemis != 0 {
                 S.insertSemi = insertSemi
         }
 
         // TODO(gri): The scanner API should change such that the literal string
         //            is only valid if an actual literal was scanned. This will
         //            permit a more efficient implementation.
         return S.file.Pos(offs), tok, string(S.src[offs:S.offset])
 }