Eliminate unary plus with hex literals

runtime/vm/scanner.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/scanner.h"
 
 #include "platform/assert.h"
 #include "vm/flags.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
@@ skipping 613 matching lines @@
     }
     switch (c0_) {
       case '\0':
         current_token_.kind = Token::kEOS;
         break;
 
       case '+':  // +  ++  +=
         ReadChar();
         current_token_.kind =
             IsNumberStart(c0_) ? Token::kTIGHTADD : Token::kADD;
-        if (c0_ == '+') {
+        // Unary + is not allowed for hexadecimal integers, so treat the
+        // + as a binary operator.
+        if ((c0_ == '0') &&
+            ((LookaheadChar(1) == 'x') || (LookaheadChar(1) == 'X'))) {
+          current_token_.kind = Token::kADD;
+        } else if (c0_ == '+') {
           Recognize(Token::kINCR);
         } else if (c0_ == '=') {
           Recognize(Token::kASSIGN_ADD);
         }
         break;
 
       case '-':  // -  --  -=
         Recognize(Token::kSUB);
         if (c0_ == '-') {
           Recognize(Token::kDECR);
@@ skipping 275 matching lines @@
               "%c%"PRIxPTR, kPrivateKeySeparator, key_value);
   const String& result = String::Handle(String::New(private_key));
   return result.raw();
 }
 
 
 void Scanner::InitOnce() {
 }
 
 }  // namespace dart