experiment with -Wimplicit-fallthrough

base/third_party/icu/icu_utf.cc

 /*
 ******************************************************************************
 *
 *   Copyright (C) 1999-2006, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 ******************************************************************************
 *   file name:  utf_impl.c
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 1999sep13
 *   created by: Markus W. Scherer
 *
 *   This file provides implementation functions for macros in the utfXX.h
 *   that would otherwise be too long as macros.
 */
 
+#include "base/compiler_specific.h"
 #include "base/third_party/icu/icu_utf.h"
 
 namespace base_icu {
 
 /**
  * UTF8_ERROR_VALUE_1 and UTF8_ERROR_VALUE_2 are special error values for UTF-8,
  * which need 1 or 2 bytes in UTF-8:
  * \code
  * U+0015 = NAK = Negative Acknowledge, C0 control character
  * U+009f = highest C1 control character
@@ skipping 122 matching lines @@
         case 3:
             trail=s[(i)++];
             (c)=((c)<<6)|(trail&0x3f);
             if(c<0x110) {
                 illegal|=(trail&0xc0)^0x80;
             } else {
                 /* code point>0x10ffff, outside Unicode */
                 illegal=1;
                 break;
             }
+            FALLTHROUGH_INTENDED;
         case 2:
             trail=s[(i)++];
             (c)=((c)<<6)|(trail&0x3f);
             illegal|=(trail&0xc0)^0x80;
+            FALLTHROUGH_INTENDED;
         case 1:
             trail=s[(i)++];
             (c)=((c)<<6)|(trail&0x3f);
             illegal|=(trail&0xc0)^0x80;
             break;
         case 0:
             if(strict>=0) {
                 return CBUTF8_ERROR_VALUE_1;
             } else {
                 return CBU_SENTINEL;
@@ skipping 43 matching lines @@
             c=utf8_errorValue[i-i0];
         } else {
             c=CBU_SENTINEL;
         }
     }
     *pi=i;
     return c;
 }
 
 }  // namespace base_icu