X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fcfg%2Fcompiler.h;h=e8a76ab1af9e3fddb5af5bf8a753ab00fb670315;hb=493d98f6f007571506feb2d6b4250b63e2edc7e1;hp=907b23e6d1749cf496a675937e580898d1ee0f73;hpb=a3f9ca9d86b7f8da31204746cc32e13c2dbe5ed0;p=bertos.git

diff --git a/bertos/cfg/compiler.h b/bertos/cfg/compiler.h
index 907b23e6..e8a76ab1 100644
--- a/bertos/cfg/compiler.h
+++ b/bertos/cfg/compiler.h
@@ -531,7 +531,22 @@ typedef unsigned char sigmask_t; /**< Type for signal masks. */
 	 *
 	 * \note This macro is non-standard, but implements a very common idiom
 	 */
-	#define countof(a)  (sizeof(a) / sizeof(*(a)))
+	#if defined(__GNUC__) && !defined(__cplusplus)
+		/*
+		 * Perform a compile time type checking: countof() can only
+		 * work with static arrays, so throw a compile time error if a
+		 * pointer is passed as argument.
+		 *
+		 * NOTE: the construct __builtin_types_compatible_p() is only
+		 * available for C.
+		 */
+		#define countof(a) (sizeof(a) / sizeof(*(a)) + \
+			sizeof(typeof(int[1 - 2 * \
+				!!__builtin_types_compatible_p(typeof(a), \
+						typeof(&a[0]))])) * 0)
+	#else
+		#define countof(a)  (sizeof(a) / sizeof(*(a)))
+	#endif
 #endif
 #ifndef alignof
 	/**