(decl_attributes): Allow format attributes on old style

(non-prototype) function declarations.

From-SVN: r6463

gcc/c-common.c

 /* Subroutines shared by all languages that are variants of C.
-   Copyright (C) 1992, 1993 Free Software Foundation, Inc.
+   Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -345,9 +345,12 @@ decl_attributes (decl, attributes)
 	    continue;
 	  }
 
-	/* Verify that the format_num argument is actually a string, in case
-	   the format attribute is in error.  */
+	/* If a parameter list is specified, verify that the format_num
+	   argument is actually a string, in case the format attribute
+	   is in error.  */
 	argument = TYPE_ARG_TYPES (TREE_TYPE (decl));
+	if (argument)
+	  {
 	    for (arg_num = 1; ; ++arg_num)
 	      {
 		if (argument == 0 || arg_num == format_num)
@@ -375,6 +378,7 @@ decl_attributes (decl, attributes)
 		    continue;
 		  }
 	      }
+	  }
 
 	record_function_format (DECL_NAME (decl), DECL_ASSEMBLER_NAME (decl),
 				is_scan, format_num, first_arg_num);