Index: sys/sys/fcntl.h
===================================================================
--- sys/sys/fcntl.h
+++ sys/sys/fcntl.h
@@ -207,35 +207,56 @@
  * Constants used for fcntl(2)
  */
 
+#define	__fcntl_type_attr(type)	__datatype_type_tag(fcntl, type)
+
 /* command values */
-#define	F_DUPFD		0		/* duplicate file descriptor */
-#define	F_GETFD		1		/* get file descriptor flags */
-#define	F_SETFD		2		/* set file descriptor flags */
-#define	F_GETFL		3		/* get file status flags */
-#define	F_SETFL		4		/* set file status flags */
+static const int __F_DUPFD __fcntl_type_attr(int) = 0;
+#define	F_DUPFD __F_DUPFD		/* duplicate file descriptor */
+static const int __F_GETFD __fcntl_type_attr(void) = 1;
+#define	F_GETFD __F_GETFD		/* get file descriptor flags */
+static const int __F_SETFD __fcntl_type_attr(int) = 2;
+#define	F_SETFD __F_SETFD		/* set file descriptor flags */
+static const int __F_GETFL __fcntl_type_attr(void) = 3;
+#define	F_GETFL __F_GETFL		/* get file status flags */
+static const int __F_SETFL __fcntl_type_attr(int) = 4;
+#define	F_SETFL __F_SETFL		/* set file status flags */
 #if __XSI_VISIBLE || __POSIX_VISIBLE >= 200112
-#define	F_GETOWN	5		/* get SIGIO/SIGURG proc/pgrp */
-#define	F_SETOWN	6		/* set SIGIO/SIGURG proc/pgrp */
+static const int __F_GETOWN __fcntl_type_attr(pid_t) = 5;
+#define	F_GETOWN __F_GETOWN		/* get SIGIO/SIGURG proc/pgrp */
+static const int __F_SETOWN __fcntl_type_attr(pid_t) = 6;
+#define	F_SETOWN __F_SETOWN		/* set SIGIO/SIGURG proc/pgrp */
 #endif
 #if __BSD_VISIBLE
-#define	F_OGETLK	7		/* get record locking information */
-#define	F_OSETLK	8		/* set record locking information */
-#define	F_OSETLKW	9		/* F_SETLK; wait if blocked */
-#define	F_DUP2FD	10		/* duplicate file descriptor to arg */
+static const int __F_OGETLK __fcntl_type_attr(int) = 7;
+#define	F_OGETLK __F_OGETLK		/* get record locking information */
+static const int __F_OSETLK __fcntl_type_attr(int) = 8;
+#define	F_OSETLK __F_OSETLK		/* set record locking information */
+static const int __F_OSETLKW __fcntl_type_attr(int) = 9;
+#define	F_OSETLKW __F_OSETLKW		/* F_SETLK; wait if blocked */
+static const int __F_DUP2FD __fcntl_type_attr(int) = 10;
+#define	F_DUP2FD __F_DUP2FD		/* duplicate file descriptor to arg */
 #endif
-#define	F_GETLK		11		/* get record locking information */
-#define	F_SETLK		12		/* set record locking information */
-#define	F_SETLKW	13		/* F_SETLK; wait if blocked */
+static const int __F_GETLK __fcntl_type_attr(__intptr_t) = 11;
+#define	F_GETLK __F_GETLK		/* get record locking information */
+static const int __F_SETLK __fcntl_type_attr(__intptr_t) = 12;
+#define	F_SETLK __F_SETLK		/* set record locking information */
+static const int __F_SETLKW __fcntl_type_attr(__intptr_t) = 13;
+#define	F_SETLKW __F_SETLKW		/* F_SETLK; wait if blocked */
 #if __BSD_VISIBLE
-#define	F_SETLK_REMOTE	14		/* debugging support for remote locks */
-#define	F_READAHEAD	15		/* read ahead */
-#define	F_RDAHEAD	16		/* Darwin compatible read ahead */
+static const int __F_SETLK_REMOTE __fcntl_type_attr(__intptr_t) = 14;
+#define	F_SETLK_REMOTE __F_SETLK_REMOTE	/* debugging support for remote locks */
+static const int __F_READAHEAD __fcntl_type_attr(int) = 15;
+#define	F_READAHEAD __F_READAHEAD	/* read ahead */
+static const int __F_RDAHEAD __fcntl_type_attr(int) = 16;
+#define	F_RDAHEAD __F_RDAHEAD		/* Darwin compatible read ahead */
 #endif
 #if __POSIX_VISIBLE >= 200809
-#define	F_DUPFD_CLOEXEC	17		/* Like F_DUPFD, but FD_CLOEXEC is set */
+static const int __F_DUPFD_CLOEXEC __fcntl_type_attr(int) = 17;
+#define	F_DUPFD_CLOEXEC __F_DUPFD_CLOEXEC /* Like F_DUPFD, but FD_CLOEXEC is set */
 #endif
 #if __BSD_VISIBLE
-#define	F_DUP2FD_CLOEXEC 18		/* Like F_DUP2FD, but FD_CLOEXEC is set */
+static const int __F_DUP2FD_CLOEXEC __fcntl_type_attr(int) = 18;
+#define	F_DUP2FD_CLOEXEC __F_DUP2FD_CLOEXEC /* Like F_DUP2FD, but FD_CLOEXEC is set */
 #endif
 
 /* file descriptor flags (F_GETFD, F_SETFD) */
@@ -308,7 +329,7 @@
 __BEGIN_DECLS
 int	open(const char *, int, ...);
 int	creat(const char *, mode_t);
-int	fcntl(int, int, ...);
+int	fcntl(int, int, ...) __arg_type_tag(fcntl, 3, 2);
 #if __BSD_VISIBLE
 int	flock(int, int);
 #endif