From: Olivier Houchard <ohouchard@haproxy.com>
Date: Wed, 24 Jan 2018 17:17:06 +0000 (+0100)
Subject: MINOR: compiler: introduce offsetoff().
X-Git-Tag: v1.9-dev1~452
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=928fbfa;p=thirdparty%2Fhaproxy.git

MINOR: compiler: introduce offsetoff().

Add a offsetof() macro, if it is no there already.
---

diff --git a/include/common/compiler.h b/include/common/compiler.h
index a13aad5c62..125c473997 100644
--- a/include/common/compiler.h
+++ b/include/common/compiler.h
@@ -107,5 +107,23 @@
 #endif
 #endif
 
+#ifndef __GNUC_PREREQ__
+#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
+#define __GNUC_PREREQ__(ma, mi) \
+        (__GNUC__ > (ma) || __GNUC__ == (ma) && __GNUC_MINOR__ >= (mi))
+#else
+#define __GNUC_PREREQ__(ma, mi) 0
+#endif
+#endif
+
+#ifndef offsetof
+#if __GNUC_PREREQ__(4, 1)
+#define offsetof(type, field)  __builtin_offsetof(type, field)
+#else
+#define offsetof(type, field) \
+        ((__size_t)(__uintptr_t)((const volatile void *)&((type *)0)->field))
+#endif
+#endif
+
 
 #endif /* _COMMON_COMPILER_H */