X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=para.h;h=08eb0ee6c20ab1a7779cc3f10de2b5fca094f44b;hp=f095a6aa385d2f717048f1e25e15741a15632617;hb=e4db7671a91a7552c642acc979f0eb278f8d467f;hpb=1199398188c1a5ee0e8bc147400d8532bc874700

diff --git a/para.h b/para.h
index f095a6aa..08eb0ee6 100644
--- a/para.h
+++ b/para.h
@@ -180,8 +180,23 @@ _static_inline_ long int para_random(unsigned max)
 	typeof(y) _divisor = y; \
 	((x) + _divisor - 1) / _divisor; })
 
+/**
+ * Assert a build-time dependency, as an expression.
+ *
+ * \param cond The compile-time condition which must be true.
+ *
+ * Compilation will fail if the condition isn't true, or can't be evaluated by
+ * the compiler. This can be used in an expression: its value is "0".
+ *
+ * Taken from ccan.
+ */
+#define EXPR_BUILD_ASSERT(cond) (sizeof(char [1 - 2 * !(cond)]) - 1)
+
+/* &a[0] degrades to a pointer: a different type from an array */
+#define _array_size_chk(arr) EXPR_BUILD_ASSERT(\
+	!__builtin_types_compatible_p(typeof(arr), typeof(&(arr)[0])))
 /** Get the size of an array */
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + _array_size_chk(arr))
 
 /**
  * Wrapper for isspace.
@@ -206,6 +221,9 @@ _static_inline_ long int para_random(unsigned max)
 /** Used to avoid a shortcoming in vim's syntax highlighting. */
 #define EMBRACE(...) { __VA_ARGS__}
 
+/** A nice cup of STFU for Mr gcc. */
+#define do_nothing do {/* nothing */} while (0)
+
 /**
  * The sample formats supported by paraslash.
  *