Index: sys/sys/cdefs.h
===================================================================
RCS file: /cvsroot/src/sys/sys/cdefs.h,v
retrieving revision 1.156
diff -u -p -r1.156 cdefs.h
--- sys/sys/cdefs.h	16 Jan 2021 23:51:51 -0000	1.156
+++ sys/sys/cdefs.h	22 Apr 2021 19:40:08 -0000
@@ -114,6 +114,14 @@
 #define	__const		const		/* define reserved names to standard */
 #define	__signed	signed
 #define	__volatile	volatile
+
+#define	__CONCAT3(a,b,c)		a ## b ## c
+#define	__CONCAT4(a,b,c,d)		a ## b ## c ## d
+#define	__CONCAT5(a,b,c,d,e)		a ## b ## c ## d ## e
+#define	__CONCAT6(a,b,c,d,e,f)		a ## b ## c ## d ## e ## f
+#define	__CONCAT7(a,b,c,d,e,f,g)	a ## b ## c ## d ## e ## f ## g
+#define	__CONCAT8(a,b,c,d,e,f,g,h)	a ## b ## c ## d ## e ## f ## g ## h
+
 #if defined(__cplusplus) || defined(__PCC__)
 #define	__inline	inline		/* convert to C++/C99 keyword */
 #else
@@ -127,6 +135,13 @@
 #define	__CONCAT(x,y)	x/**/y
 #define	__STRING(x)	"x"
 
+#define	__CONCAT3(a,b,c)		a/**/b/**/c
+#define	__CONCAT4(a,b,c,d)		a/**/b/**/c/**/d
+#define	__CONCAT5(a,b,c,d,e)		a/**/b/**/c/**/d/**/e
+#define	__CONCAT6(a,b,c,d,e,f)		a/**/b/**/c/**/d/**/e/**/f
+#define	__CONCAT7(a,b,c,d,e,f,g)	a/**/b/**/c/**/d/**/e/**/f/**/g
+#define	__CONCAT8(a,b,c,d,e,f,g,h)	a/**/b/**/c/**/d/**/e/**/f/**/g/**/h
+
 #ifndef __GNUC__
 #define	__const				/* delete pseudo-ANSI C keywords */
 #define	__inline