Add attributions so printf like functions can have their arguments checked.

runtime/vm/os.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_OS_H_
 #define VM_OS_H_
 
 #include "vm/globals.h"
 
 // Forward declarations.
@@ skipping 44 matching lines @@
   // Returns the stack size limit.
   static uword GetStackSizeLimit();
 
   // Returns number of available processor cores.
   static int NumberOfAvailableProcessors();
 
   // Sleep the currently executing thread for millis ms.
   static void Sleep(int64_t millis);
 
   // Print formatted output to stdout/stderr for debugging.
-  static void Print(const char* format, ...);
-  static void PrintErr(const char* format, ...);
+  static void Print(const char* format, ...) PRINTF_ATTRIBUTE(1, 2);
+  static void PrintErr(const char* format, ...) PRINTF_ATTRIBUTE(1, 2);
   static void VFPrint(FILE* stream, const char* format, va_list args);
   // Print formatted output info a buffer.
   //
   // Does not write more than size characters (including the trailing '\0').
   //
   // Returns the number of characters (excluding the trailing '\0')
   // that would been written if the buffer had been big enough.  If
   // the return value is greater or equal than the given size then the
   // output has been truncated.  The return value is never negative.
   //
   // The buffer will always be terminated by a '\0', unless the buffer
   // is of size 0.  The buffer might be NULL if the size is 0.
   //
   // This specification conforms to C99 standard which is implemented
   // by glibc 2.1+ with one exception: the C99 standard allows a
   // negative return value.  We will terminate the vm rather than let
   // that occur.
-  static int SNPrint(char* str, size_t size, const char* format, ...);
+  static int SNPrint(char* str, size_t size, const char* format, ...)
+      PRINTF_ATTRIBUTE(3, 4);
   static int VSNPrint(char* str, size_t size,
                       const char* format,
                       va_list args);
 
   // Converts a C string which represents a valid dart integer into a 64 bit
   // value.
   // Returns false if it is unable to convert the string to a 64 bit value,
   // the failure could be because of underflow/overflow or invalid characters.
   // On success the function returns true and 'value' contains the converted
   // value.
   static bool StringToInt64(const char* str, int64_t* value);
 
   // Initialize the OS class.
   static void InitOnce();
 
   // Shut down the OS class.
   static void Shutdown();
 
   static void Abort();
 
   static void Exit(int code);
 };
 
 }  // namespace dart
 
 #endif  // VM_OS_H_