Use PrintF instead of fprintf.

src/flags.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 349 matching lines @@
       // lookup the flag
       Flag* flag = FindFlag(name);
       if (flag == NULL) {
         if (remove_flags) {
           // We don't recognize this flag but since we're removing
           // the flags we recognize we assume that the remaining flags
           // will be processed somewhere else so this flag might make
           // sense there.
           continue;
         } else {
-          fprintf(stderr, "Error: unrecognized flag %s\n"
-                  "Try --help for options\n", arg);
+          PrintF(stderr, "Error: unrecognized flag %s\n"
+                 "Try --help for options\n", arg);
           return_code = j;
           break;
         }
       }
 
       // if we still need a flag value, use the next argument if available
       if (flag->type() != Flag::TYPE_BOOL &&
           flag->type() != Flag::TYPE_ARGS &&
           value == NULL) {
         if (i < *argc) {
           value = argv[i++];
         } else {
-          fprintf(stderr, "Error: missing value for flag %s of type %s\n"
-                  "Try --help for options\n",
-                  arg, Type2String(flag->type()));
+          PrintF(stderr, "Error: missing value for flag %s of type %s\n"
+                 "Try --help for options\n",
+                 arg, Type2String(flag->type()));
           return_code = j;
           break;
         }
       }
 
       // set the flag
       char* endp = const_cast<char*>("");  // *endp is only read
       switch (flag->type()) {
         case Flag::TYPE_BOOL:
           *flag->bool_variable() = !is_bool;
@@ skipping 20 matching lines @@
           *flag->args_variable() = JSArguments::Create(js_argc, js_argv);
           i = *argc;  // Consume all arguments
           break;
         }
       }
 
       // handle errors
       if ((flag->type() == Flag::TYPE_BOOL && value != NULL) ||
           (flag->type() != Flag::TYPE_BOOL && is_bool) ||
           *endp != '\0') {
-        fprintf(stderr, "Error: illegal value for flag %s of type %s\n"
-                "Try --help for options\n",
-                arg, Type2String(flag->type()));
+        PrintF(stderr, "Error: illegal value for flag %s of type %s\n"
+               "Try --help for options\n",
+               arg, Type2String(flag->type()));
         return_code = j;
         break;
       }
 
       // remove the flag & value from the command
       if (remove_flags) {
         while (j < i) {
           argv[j++] = NULL;
         }
       }
@@ skipping 99 matching lines @@
 }
 
 
 void FlagList::EnforceFlagImplications() {
 #define FLAG_MODE_DEFINE_IMPLICATIONS
 #include "flag-definitions.h"
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 }
 
 } }  // namespace v8::internal