From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Wed, 9 Aug 2017 21:55:17 +0000 (-0700)
Subject: Explicitly handle gcc in FOLLY_MAYBE_UNUSED
X-Git-Tag: v2017.08.14.00~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=eb8f3c3c266b76adc3b6ad52c042a2de0e75b9e8;p=folly.git

Explicitly handle gcc in FOLLY_MAYBE_UNUSED

Summary:
[Folly] Explicitly handle gcc in `FOLLY_MAYBE_UNUSED`.

Fixes build break from {D5562220}.

Reviewed By: Orvid

Differential Revision: D5594288

fbshipit-source-id: 5aa2dcb6133d53a0eb20d34b67c8e4407dd2b7ca
---

diff --git a/folly/CppAttributes.h b/folly/CppAttributes.h
index f435212d..7a13f615 100644
--- a/folly/CppAttributes.h
+++ b/folly/CppAttributes.h
@@ -22,6 +22,12 @@
 
 #pragma once
 
+#ifndef __has_attribute
+#define FOLLY_HAS_ATTRIBUTE(x) 0
+#else
+#define FOLLY_HAS_ATTRIBUTE(x) __has_attribute(x)
+#endif
+
 #ifndef __has_cpp_attribute
 #define FOLLY_HAS_CPP_ATTRIBUTE(x) 0
 #else
@@ -65,7 +71,9 @@
  *    #endif
  *  }
  */
-#if FOLLY_HAS_CPP_ATTRIBUTE(__unused__)
+#if FOLLY_HAS_CPP_ATTRIBUTE(maybe_unused)
+#define FOLLY_MAYBE_UNUSED [[maybe_unused]]
+#elif FOLLY_HAS_ATTRIBUTE(__unused__) || __GNUC__
 #define FOLLY_MAYBE_UNUSED __attribute__((__unused__))
 #else
 #define FOLLY_MAYBE_UNUSED