[PATCH 2/2] Use static_assert for STATIC_ASSERT for C++11 onwards

[David Malcolm]

C++11 has a
  static_assert (COND, MESSAGE)
which gives more readable error messages for STATIC_ASSERT than our
current implementation.

This patch makes us use it if __cplusplus >= 201103L

There's also a provisional static_assert (COND) in C++1z, but presumably
we should wait until that one is fully standardized before using it.

Bootstrapped&regrtested on x86_64-pc-linux-gnu (in conjunction
with the previous patch)

OK for trunk?

gcc/ChangeLog:
        * system.h (STATIC_ASSERT): Use static_assert if building
        with C++11 onwards.
---
 gcc/system.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/system.h b/gcc/system.h
index 78a7da6..8a17197 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -752,9 +752,14 @@ extern void fancy_abort (const char *, int, const char *) 
ATTRIBUTE_NORETURN;
 #define STATIC_CONSTANT_P(X) (false && (X))
 #endif
 
-/* Until we can use C++11's static_assert.  */
+/* static_assert (COND, MESSAGE) is available in C++11 onwards.  */
+#if __cplusplus >= 201103L
+#define STATIC_ASSERT(X) \
+  static_assert ((X), #X)
+#else
 #define STATIC_ASSERT(X) \
   typedef int assertion1[(X) ? 1 : -1] ATTRIBUTE_UNUSED
+#endif
 
 /* Provide a fake boolean type.  We make no attempt to use the
    C99 _Bool, as it may not be available in the bootstrap compiler,
-- 
1.8.5.3