explicitly ignore a place where clang warns but gcc doesn't
diff --git a/aos/linux_code/ipc_lib/queue.cc b/aos/linux_code/ipc_lib/queue.cc
index 148deed..3cdb74c 100644
--- a/aos/linux_code/ipc_lib/queue.cc
+++ b/aos/linux_code/ipc_lib/queue.cc
@@ -86,6 +86,11 @@
// Padding to make the total size 8 bytes if we have 4-byte pointers or bump
// it to 16 if a pointer is 8 bytes by itself.
#if __SIZEOF_POINTER__ == 8
+#ifdef __clang__
+ // Clang is smart enough to realize this is unused, but GCC doesn't like the
+ // attribute here...
+ __attribute__((unused))
+#endif
char padding[4];
#elif __SIZEOF_POINTER__ == 4
// No padding needed to get 8 byte total size.