misc: Fix compiler warnings about the static_assert macro with gcc 4.8
The modified macro is still working on a gcc 4.7 and gcc 4.8 after the
removal of the typedef and addition of the unused attribute.
include/osmocom/core/msgb.h: In function ‘msgb_alloc_headroom’:
include/osmocom/core/utils.h:40:51: warning: typedef ‘dummyheadroom_bigger’ locally defined but not used [-Wunused-local-typedefs]
#define osmo_static_assert(exp, name) typedef int dummy##name [(exp) ? 1 : -1];
^
include/osmocom/core/msgb.h:386:2: note: in expansion of macro ‘osmo_static_assert’
osmo_static_assert(size > headroom, headroom_bigger);
^
diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h
index f8e6fc9..c8efce2 100644
--- a/include/osmocom/core/utils.h
+++ b/include/osmocom/core/utils.h
@@ -37,7 +37,7 @@
char *osmo_hexdump_nospc(const unsigned char *buf, int len);
char *osmo_osmo_hexdump_nospc(const unsigned char *buf, int len) __attribute__((__deprecated__));
-#define osmo_static_assert(exp, name) typedef int dummy##name [(exp) ? 1 : -1];
+#define osmo_static_assert(exp, name) int dummy##name [(exp) ? 1 : -1] __attribute__((__unused__));
void osmo_str2lower(char *out, const char *in);
void osmo_str2upper(char *out, const char *in);