printf("%s", NULL) in make(1)

[Theo Buehler]

Found a bunch of these in my /var/log/messages:

Oct  2 18:30:58 idefix make: vfprintf %s NULL in "Applying :%c to "%s" "
Oct  2 18:30:58 idefix make: vfprintf %s NULL in "Result is "%s" "

To reproduce, issue 'make -n -d v' in a simple port, e.g. sysutils/cpuid

Index: usr.bin/make/varmodifiers.c
===================================================================
RCS file: /var/cvs/src/usr.bin/make/varmodifiers.c,v
retrieving revision 1.43
diff -u -p -r1.43 varmodifiers.c
--- usr.bin/make/varmodifiers.c 15 Nov 2015 06:19:22 -0000      1.43
+++ usr.bin/make/varmodifiers.c 2 Oct 2016 16:32:07 -0000
@@ -1453,7 +1453,8 @@ VarModifiers_Apply(char *str, const stru
 
                tstr++;
                if (DEBUG(VAR))
-                       printf("Applying :%c to \"%s\"\n", *tstr, str);
+                       printf("Applying :%c to \"%s\"\n", *tstr, str ? str :
+                           "(null)");
 
                mod = choose_mod[(unsigned char)*tstr];
                arg = NULL;
@@ -1502,7 +1503,7 @@ VarModifiers_Apply(char *str, const stru
                        break;
                }
                if (DEBUG(VAR))
-                       printf("Result is \"%s\"\n", str);
+                       printf("Result is \"%s\"\n", str ? str : "(null)");
        }
        if (*tstr == '\0')
                Parse_Error(PARSE_FATAL, "Unclosed variable specification");