[Qemu-devel] [PATCH 2/8] add QEMU_BUILD_BUG_EXPR

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Glib's GLIB_STATIC_ASSERT_EXPR can't be used in an array initialisation
where as this rune can.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/qemu/compiler.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 157698b..b6ad32c 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -88,6 +88,11 @@
 #define QEMU_BUILD_BUG_ON(x) \
     typedef char glue(qemu_build_bug_on__,__LINE__)[(x)?-1:1] __attribute__((unused));
 
+/* Evaluates to 0 or fails; seems to work in an array initialisation unlike
+ * GLIB_STATIC_ASSERT_EXPR.  Fails on true.
+ */
+#define QEMU_BUILD_BUG_EXPR(x) (sizeof(int [(x)?-1:1])-sizeof(int [1]))
+
 #if defined __GNUC__
 # if !QEMU_GNUC_PREREQ(4, 4)
    /* gcc versions before 4.4.x don't support gnu_printf, so use printf. */
-- 
2.9.3