Proper reporting of illegal characters in source code

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"
 #include "vm/symbols.h"
 #include "vm/thread.h"
 #include "vm/token.h"
+#include "vm/unicode.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, disable_privacy, false, "Disable library privacy.");
 DEFINE_FLAG(bool, print_tokens, false, "Print scanned tokens.");
 
 void Scanner::InitKeywordTable() {
   ObjectStore* object_store = Isolate::Current()->object_store();
   keyword_symbol_table_ = object_store->keyword_symbols();
   if (keyword_symbol_table_.IsNull()) {
@@ skipping 851 matching lines @@
         ScanLibraryTag();
         break;
 
       default:
         if (IsIdentStartChar(c0_)) {
           ScanIdent();
         } else if (IsDecimalDigit(c0_)) {
           ScanNumber(false);
         } else {
           char msg[128];
+          char utf8_char[5];
+          int len = Utf8::Encode(c0_, utf8_char);
+          utf8_char[len] = '\0';
           OS::SNPrint(msg, sizeof(msg),
-                      "unexpected character: %c  (%02x)\n", c0_, c0_);
+                      "unexpected character: '%s' (U+%04X)\n", utf8_char, c0_);
           ErrorMsg(msg);
           ReadChar();
         }
     }
   } while (current_token_.kind == Token::kWHITESP);
   current_token_.length = lookahead_pos_ - token_start_;
 }
 
 
 void Scanner::ScanAll(GrowableTokenStream* token_stream) {
@@ skipping 85 matching lines @@
               "%c%#"Px"", kPrivateKeySeparator, key_value);
   const String& result = String::Handle(String::New(private_key, Heap::kOld));
   return result.raw();
 }
 
 
 void Scanner::InitOnce() {
 }
 
 }  // namespace dart