Prefix compile-time typedef checks with __attribute__((unused))

runtime/platform/globals.h

 // 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.
 
 #ifndef PLATFORM_GLOBALS_H_
 #define PLATFORM_GLOBALS_H_
 
 // __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
 // enable platform independent printf format specifiers.
 #ifndef __STDC_FORMAT_MACROS
@@ skipping 155 matching lines @@
 // See: http://msdn.microsoft.com/en-us/library/z8y1yy88.aspx for an
 // explanation of some the cases when a function can never be inlined.
 #ifdef _MSC_VER
 #define DART_FORCE_INLINE __forceinline
 #elif __GNUC__
 #define DART_FORCE_INLINE inline __attribute__((always_inline))
 #else
 #error Automatic compiler detection failed.
 #endif
 
+// DART_UNUSED inidicates to the compiler that a variable/typedef is expected
+// to be unused and disables the related warning.
+#ifdef __GNUC__
+#define DART_UNUSED __attribute__((unused))
+#else
+#define DART_UNUSED
+#endif
+
 #if !defined(TARGET_ARCH_MIPS)
 #if !defined(TARGET_ARCH_ARM)
 #if !defined(TARGET_ARCH_X64)
 #if !defined(TARGET_ARCH_IA32)
 // No target architecture specified pick the one matching the host architecture.
 #if defined(HOST_ARCH_MIPS)
 #define TARGET_ARCH_MIPS 1
 #elif defined(HOST_ARCH_ARM)
 #define TARGET_ARCH_ARM 1
 #elif defined(HOST_ARCH_X64)
@@ skipping 199 matching lines @@
 // There is an additional use for bit_cast. Recent gccs will warn when
 // they see casts that may result in breakage due to the type-based
 // aliasing rule. If you have checked that there is no breakage you
 // can use bit_cast to cast one pointer type to another. This confuses
 // gcc enough that it can no longer see that you have cast one pointer
 // type to another thus avoiding the warning.
 template <class D, class S>
 inline D bit_cast(const S& source) {
   // Compile time assertion: sizeof(D) == sizeof(S). A compile error
   // here means your D and S have different sizes.
-  typedef char VerifySizesAreEqual[sizeof(D) == sizeof(S) ? 1 : -1];
+  DART_UNUSED typedef char VerifySizesAreEqual[sizeof(D) == sizeof(S) ? 1 : -1];
 
   D destination;
   // This use of memcpy is safe: source and destination cannot overlap.
   memcpy(&destination, &source, sizeof(destination));
   return destination;
 }
 
 
 // Similar to bit_cast, but allows copying from types of unrelated
 // sizes. This method was introduced to enable the strict aliasing
@@ skipping 47 matching lines @@
 // N.B.: As the GCC manual states, "[s]ince non-static C++ methods
 // have an implicit 'this' argument, the arguments of such methods
 // should be counted from two, not one."
 #define PRINTF_ATTRIBUTE(string_index, first_to_check) \
   __attribute__((__format__(__printf__, string_index, first_to_check)))
 #else
 #define PRINTF_ATTRIBUTE(string_index, first_to_check)
 #endif
 
 #endif  // PLATFORM_GLOBALS_H_