From: Martin Willi <martin@revosec.ch>
Date: Fri, 4 Jul 2014 12:35:27 +0000 (+0200)
Subject: utils: Add some initial build time assertion macros
X-Git-Tag: 5.2.1dr1~100
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb6be261974788d971226d7508bcbc49af86e96e;p=thirdparty%2Fstrongswan.git

utils: Add some initial build time assertion macros

These are useful to assert constants during build time. We evaluate the
expression to 0 when valid, so we can safely use the evaluated value.
---

diff --git a/src/libstrongswan/utils/utils.h b/src/libstrongswan/utils/utils.h
index 1b822dd610..cb60c6e3e2 100644
--- a/src/libstrongswan/utils/utils.h
+++ b/src/libstrongswan/utils/utils.h
@@ -59,6 +59,20 @@
  */
 #define BUF_LEN 512
 
+/**
+ * Build assertion macro for integer expressions, evaluates to 0
+ */
+#define BUILD_ASSERT(x) (sizeof(char[(x) ? 0 : -1]))
+
+/**
+ * Build time check to assert a is an array, evaluates to 0
+ *
+ * The address of an array element has a pointer type, which is not compatible
+ * to the array type.
+ */
+#define BUILD_ASSERT_ARRAY(a) \
+		BUILD_ASSERT(!__builtin_types_compatible_p(typeof(a), typeof(&(a)[0])))
+
 /**
  * General purpose boolean type.
  */