vm_core.h: suppress warnings

* vm_core.h (UNINITIALIZED_VAR): suppress warnings by clang 4.2.
  [ruby-core:51742] [Bug #7756]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39855 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/vm_core.h b/vm_core.h
index 5cce489e21..576ba8e0d9 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -115,7 +115,9 @@
 #define UNLIKELY(x) (x)
 #endif /* __GNUC__ >= 3 */
 
-#if __GNUC__ >= 3
+#if (defined(__clang__) && (__clang_major__ == 4 && __clang_minor__ == 2))
+#define UNINITIALIZED_VAR(x) x __attribute__((unused))
+#elif defined(__GNUC__) && __GNUC__ >= 3
 #define UNINITIALIZED_VAR(x) x = x
 #else
 #define UNINITIALIZED_VAR(x) x