X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fcfg%2Fcompiler.h;h=843af838c502621f473713c8dff6a945357b28e6;hb=03b9fa23fa8d7c7a49f817cd2108ab47b3afe7ec;hp=907b23e6d1749cf496a675937e580898d1ee0f73;hpb=a3f9ca9d86b7f8da31204746cc32e13c2dbe5ed0;p=bertos.git

diff --git a/bertos/cfg/compiler.h b/bertos/cfg/compiler.h
index 907b23e6..843af838 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)) +		\
+				STATIC_ASSERT_EXPR(			\
+					!__builtin_types_compatible_p(	\
+						typeof(a), typeof(&a[0]))))
+	#else
+		#define countof(a)  (sizeof(a) / sizeof(*(a)))
+	#endif
 #endif
 #ifndef alignof
 	/**
@@ -565,6 +580,13 @@ typedef unsigned char sigmask_t; /**< Type for signal masks. */
 #define STATIC_ASSERT(condition)  \
 	UNUSED_VAR(extern char, STATIC_ASSERTION_FAILED__[(condition) ? 1 : -1])
 
+/**
+ * Issue a compilation error if \a __cond is false (this can be used inside an
+ * expression).
+ */
+#define STATIC_ASSERT_EXPR(__cond) \
+	(sizeof(struct { int STATIC_ASSERTION_FAILED__:!!(__cond); }) * 0)
+
 #ifndef ASSERT_TYPE_EQUAL
 	/** Ensure two variables have the same type. */
 	#define ASSERT_TYPE_EQUAL(var1, var2)  \