#https://lkml.org/lkml/2019/10/15/1009
--- src/vboxguest/include/iprt/cdefs.h	2019-11-29 10:10:18.917022165 +0100
+++ src/vboxguest/include/iprt/cdefs.h	2019-11-29 10:11:57.197016557 +0100
@@ -1166,14 +1166,15 @@
  * Tell the compiler that we're falling through to the next case in a switch.
  * @sa RT_FALL_THRU  */
 #if RT_GNUC_PREREQ(7, 0)
-# define RT_FALL_THROUGH()      __attribute__((__fallthrough__))
+# define FALL_THROUGH      __attribute__((__fallthrough__))
 #else
 # define RT_FALL_THROUGH()      (void)0
 #endif
 /** @def RT_FALL_THRU
  * Tell the compiler that we're falling thru to the next case in a switch.
  * @sa RT_FALL_THROUGH */
-#define RT_FALL_THRU()          RT_FALL_THROUGH()
+#define RT_FALL_THRU()          FALL_THROUGH
+#define RT_FALL_THROUGH()       FALL_THROUGH
 
 
 /** @def RT_IPRT_FORMAT_ATTR
--- src/vboxsf/include/iprt/cdefs.h	2019-11-29 10:20:57.644985720 +0100
+++ src/vboxsf/include/iprt/cdefs.h	2019-11-29 10:20:46.002986384 +0100
@@ -1166,14 +1166,15 @@
  * Tell the compiler that we're falling through to the next case in a switch.
  * @sa RT_FALL_THRU  */
 #if RT_GNUC_PREREQ(7, 0)
-# define RT_FALL_THROUGH()      __attribute__((fallthrough))
+# define FALL_THROUGH      __attribute__((__fallthrough__))
 #else
 # define RT_FALL_THROUGH()      (void)0
 #endif
 /** @def RT_FALL_THRU
  * Tell the compiler that we're falling thru to the next case in a switch.
  * @sa RT_FALL_THROUGH */
-#define RT_FALL_THRU()          RT_FALL_THROUGH()
+#define RT_FALL_THRU()          FALL_THROUGH
+#define RT_FALL_THROUGH()       FALL_THROUGH
 
 
 /** @def RT_IPRT_FORMAT_ATTR