Add helper macro - BOOST_ATTRIBUTE_UNUSED - to suppress unused type/variable warnings.

test/helper_macro_test.cpp

@@ -0,0 +1,60 @@
+//  Use, modification and distribution are subject to the  
+//  Boost Software License, Version 1.0. (See accompanying file  
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 
+
+#include <boost/config.hpp>
+
+int test_fallthrough(int n) 
+{ 
+   switch (n) 
+   { 
+   case 0: 
+      n++; 
+      BOOST_FALLTHROUGH; 
+   case 1: 
+      n++; 
+      break; 
+   } 
+   return n; 
+}
+
+int test_unreachable(int i)
+{
+   if(BOOST_LIKELY(i)) return i;
+
+   throw i;
+   BOOST_UNREACHABLE_RETURN(0);
+}
+
+BOOST_FORCEINLINE int always_inline(int i){ return ++i; }
+BOOST_NOINLINE int never_inline(int i){ return ++i; }
+
+BOOST_NORETURN void always_throw()
+{
+   throw 0;
+}
+
+
+#define test_fallthrough(x) foobar(x)
+
+
+int main()
+{
+   typedef int unused_type BOOST_ATTRIBUTE_UNUSED;
+   try
+   {
+      int result = test_fallthrough BOOST_PREVENT_MACRO_SUBSTITUTION(0);
+      BOOST_STATIC_CONSTANT(bool, value = 0);
+      result += test_unreachable(1);
+      result += always_inline(2);
+      result += never_inline(3);
+      if(BOOST_UNLIKELY(!result))
+         always_throw();
+   }
+   catch(int)
+   {
+      return 1;
+   }
+   return 0;
+}
+