[RFC] eal: use _Static_assert() for RTE_BUILD_BUG_ON

[Stephen Hemminger]

The method of doing sizeof a bad array element was an interesting
hack but it has a couple of problems. First, it won't work if
VLA checking is enabled. It doesn't enforce that the expression
is constant.

Replace that with the _Static_assert builtin available in
Gcc, Clang, and MSVC.

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
---
 lib/eal/include/rte_common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index c1ba32d00e47..2c63206223b8 100644
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -495,7 +495,7 @@ rte_is_aligned(const void * const __rte_restrict ptr, const unsigned int align)
 /**
  * Triggers an error at compilation time if the condition is true.
  */
-#define RTE_BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#define RTE_BUILD_BUG_ON(e) _Static_assert(!(e),  #e)
 
 /*********** Cache line related macros ********/
 
-- 
2.39.2