_ref; \
})
+#if defined __clang__
+# if __has_warning("-Wunused-but-set-variable")
+# define BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE \
+ _Pragma("GCC diagnostic ignored \"-Wunused-but-set-variable\"")
+# endif
+#endif
+
+#if !defined BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE
+# define BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE
+#endif
+
#endif