* vm_core.h: use __has_attribute() instead of __clang__major__ because

clang says "Note that marketing version numbers should not be used
  to check for language features, as different vendors use different
  numbering schemes. Instead, use the Feature Checking Macros."
  http://clang.llvm.org/docs/LanguageExtensions.html

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43116 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Wed Oct  2 15:39:13 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* vm_core.h: use __has_attribute() instead of __clang__major__ because
+	  clang says "Note that marketing version numbers should not be used
+	  to check for language features, as different vendors use different
+	  numbering schemes. Instead, use the Feature Checking Macros."
+	  http://clang.llvm.org/docs/LanguageExtensions.html
+
 Wed Oct  2 14:19:57 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (rb_io_close_write): detach tied IO for writing before closing

vm_core.h

@@ -109,7 +109,11 @@
 #define UNLIKELY(x) (x)
 #endif /* __GNUC__ >= 3 */
 
-#if (defined(__clang__) && __clang_major__ >= 4)
+#ifndef __has_attribute
+# define __has_attribute(x) 0
+#endif
+
+#if __has_attribute(unused)
 #define UNINITIALIZED_VAR(x) x __attribute__((unused))
 #elif defined(__GNUC__) && __GNUC__ >= 3
 #define UNINITIALIZED_VAR(x) x = x