etags: pacify gcc -Wstack-protector on Ubuntu 12.04 x86

* etags.c: Include <stdarg.h>.
(error): Declare as printf-style, as that's what it really is.
All uses changed.
(add_regex): Use single char rather than array-of-one char.

2 files changed, 27 insertions, 20 deletions

diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index cf7494cb5d5..fe00c29cff7 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,11 @@
+2012-05-10  Paul Eggert  <eggert@cs.ucla.edu>
+
+        etags: pacify gcc -Wstack-protector on Ubuntu 12.04 x86
+        * etags.c: Include <stdarg.h>.
+        (error): Declare as printf-style, as that's what it really is.
+        All uses changed.
+        (add_regex): Use single char rather than array-of-one char.
+
 2012-05-05  Jim Meyering  <meyering@redhat.com>
 
         * lib-src/pop.c (pop_stat, pop_list, pop_multi_first, pop_last):
diff --git a/lib-src/etags.c b/lib-src/etags.c
index c88473ad525..ccf97a8357f 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -158,6 +158,7 @@ char pot_etags_version[] = "@(#) pot revision number is 17.38.1.4";
 # endif
 #endif /* HAVE_UNISTD_H */
 
+#include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ -380,7 +381,7 @@ static void get_tag (char *, char **);
 static void analyse_regex (char *);
 static void free_regexps (void);
 static void regex_tag_multiline (void);
-static void error (const char *, const char *);
+static void error (const char *, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);
 static void suggest_asking_for_help (void) NO_RETURN;
 void fatal (const char *, const char *) NO_RETURN;
 static void pfatal (const char *) NO_RETURN;
@@ -1140,7 +1141,7 @@ main (int argc, char **argv)
       case 'o':
         if (tagfile)
           {
-            error ("-o option may only be given once.", (char *)NULL);
+            error ("-o option may only be given once.");
             suggest_asking_for_help ();
             /* NOTREACHED */
           }
@@ -1224,7 +1225,7 @@ main (int argc, char **argv)
 
   if (nincluded_files == 0 && file_count == 0)
     {
-      error ("no input files specified.", (char *)NULL);
+      error ("no input files specified.");
       suggest_asking_for_help ();
       /* NOTREACHED */
     }
@@ -1447,7 +1448,7 @@ get_language_from_langname (const char *name)
   language *lang;
 
   if (name == NULL)
-    error ("empty language name", (char *)NULL);
+    error ("empty language name");
   else
     {
       for (lang = lang_names; lang->name != NULL; lang++)
@@ -2233,7 +2234,7 @@ put_entries (register node *np)
         {
           /* Ctags mode */
           if (np->name == NULL)
-            error ("internal error: NULL name in ctags mode.", (char *)NULL);
+            error ("internal error: NULL name in ctags mode.");
 
           if (cxref_style)
             {
@@ -2773,7 +2774,7 @@ consider_token (register char *str, register int len, register int c, int *c_ext
      case dignorerest:
        return FALSE;
      default:
-       error ("internal error: definedef value.", (char *)NULL);
+       error ("internal error: definedef value.");
      }
 
    /*
@@ -3061,7 +3062,7 @@ make_C_tag (int isfun)
       make_tag (concat ("INVALID TOKEN:-->", token_name.buffer, ""),
                 token_name.len + 17, isfun, token.line,
                 token.offset+token.length+1, token.lineno, token.linepos);
-      error ("INVALID TOKEN", NULL);
+      error ("INVALID TOKEN");
     }
 
   token.valid = FALSE;
@@ -5706,7 +5707,7 @@ add_regex (char *regexp_pattern, language *lang)
 {
   static struct re_pattern_buffer zeropattern;
   char sep, *pat, *name, *modifiers;
-  char empty[] = "";
+  char empty = '\0';
   const char *err;
   struct re_pattern_buffer *patbuf;
   regexp *rp;
@@ -5719,7 +5720,7 @@ add_regex (char *regexp_pattern, language *lang)
 
   if (strlen (regexp_pattern) < 3)
     {
-      error ("null regexp", (char *)NULL);
+      error ("null regexp");
       return;
     }
   sep = regexp_pattern[0];
@@ -5738,7 +5739,7 @@ add_regex (char *regexp_pattern, language *lang)
   if (modifiers == NULL)        /* no terminating separator --> no name */
     {
       modifiers = name;
-      name = empty;
+      name = &empty;
     }
   else
     modifiers += 1;             /* skip separator */
@@ -5749,7 +5750,7 @@ add_regex (char *regexp_pattern, language *lang)
       {
       case 'N':
         if (modifiers == name)
-          error ("forcing explicit tag name but no name, ignoring", NULL);
+          error ("forcing explicit tag name but no name, ignoring");
         force_explicit_name = TRUE;
         break;
       case 'i':
@@ -5763,12 +5764,7 @@ add_regex (char *regexp_pattern, language *lang)
         need_filebuf = TRUE;
         break;
       default:
-        {
-          char wrongmod [2];
-          wrongmod[0] = modifiers[0];
-          wrongmod[1] = '\0';
-          error ("invalid regexp modifier `%s', ignoring", wrongmod);
-        }
+        error ("invalid regexp modifier `%c', ignoring", modifiers[0]);
         break;
       }
 
@@ -6423,13 +6419,16 @@ suggest_asking_for_help (void)
   exit (EXIT_FAILURE);
 }
 
-/* Print error message.  `s1' is printf control string, `s2' is arg for it. */
+/* Output a diagnostic with printf-style FORMAT and args.  */
 static void
-error (const char *s1, const char *s2)
+error (const char *format, ...)
 {
+  va_list ap;
+  va_start (ap, format);
   fprintf (stderr, "%s: ", progname);
-  fprintf (stderr, s1, s2);
+  vfprintf (stderr, format, ap);
   fprintf (stderr, "\n");
+  va_end (ap);
 }
 
 /* Return a newly-allocated string whose contents