experiment with -Wimplicit-fallthrough

base/json/json_parser.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/json/json_parser.h"
 
 #include "base/float_util.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 387 matching lines @@
 
 void JSONParser::EatWhitespaceAndComments() {
   while (pos_ < end_pos_) {
     switch (*pos_) {
       case '\r':
       case '\n':
         index_last_line_ = index_;
         // Don't increment line_number_ twice for "\r\n".
         if (!(*pos_ == '\n' && pos_ > start_pos_ && *(pos_ - 1) == '\r'))
           ++line_number_;
-        // Fall through.
+        FALLTHROUGH_INTENDED;
       case ' ':
       case '\t':
         NextChar();
         break;
       case '/':
         if (!EatComment())
           return;
         break;
       default:
         return;
@@ skipping 537 matching lines @@
                                            const std::string& description) {
   if (line || column) {
     return StringPrintf("Line: %i, column: %i, %s",
         line, column, description.c_str());
   }
   return description;
 }
 
 }  // namespace internal
 }  // namespace base