Turn on WARNS=2.

Use __FBSDID().

usr.bin/cmp/Makefile

@@ -3,5 +3,6 @@
 
 PROG=	cmp
 SRCS=	cmp.c misc.c regular.c special.c
+WARNS?=	2
 
 .include <bsd.prog.mk>

usr.bin/cmp/cmp.c

@@ -29,20 +29,21 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
- *
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char copyright[] =
 "@(#) Copyright (c) 1987, 1990, 1993, 1994\n\
 	The Regents of the University of California.  All rights reserved.\n";
-#endif /* not lint */
+#endif
 
 #ifndef lint
 static const char sccsid[] = "@(#)cmp.c	8.3 (Berkeley) 4/2/94";
-#endif /* not lint */
+#endif
 
 #include <sys/types.h>
 #include <sys/stat.h>

usr.bin/cmp/misc.c

@@ -29,14 +29,15 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
- *
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char sccsid[] = "@(#)misc.c	8.3 (Berkeley) 4/2/94";
-#endif /* not lint */
+#endif
 
 #include <sys/types.h>
 

usr.bin/cmp/regular.c

@@ -29,14 +29,15 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
- *
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char sccsid[] = "@(#)regular.c	8.3 (Berkeley) 4/2/94";
-#endif /* not lint */
+#endif
 
 #include <sys/param.h>
 #include <sys/mman.h>

usr.bin/cmp/special.c

@@ -29,14 +29,15 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
- * $FreeBSD$
- *
  */
 
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
 #ifndef lint
 static const char sccsid[] = "@(#)special.c	8.3 (Berkeley) 4/2/94";
-#endif /* not lint */
+#endif
 
 #include <sys/types.h>