There are theoretical concerns that some compilers might not trigger
build failures on attempts to define an array of size (x ? -1 : 1) where
x is a variable and make it a variable sized array instead. Let rewrite
using a struct with a negative bit field size instead as there are no
dynamic bit field sizes. This is similar to what Linux does.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
#define typeof_field(type, field) typeof(((type *)0)->field)
#define type_check(t1,t2) ((t1*)0 - (t2*)0)
+#define QEMU_BUILD_BUG_ON_STRUCT(x) \
+ struct { \
+ int:(x) ? -1 : 1; \
+ }
+
#ifdef __COUNTER__
-#define QEMU_BUILD_BUG_ON(x) \
- typedef char glue(qemu_build_bug_on__, __COUNTER__)[(x) ? -1 : 1] \
- __attribute__((unused))
+#define QEMU_BUILD_BUG_ON(x) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
+ glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
#else
#define QEMU_BUILD_BUG_ON(x)
#endif