branch-1_4 warning cleanup

Found a couple of problems on both the branch and head using some compiler 
flags.  There are several places where we assign "" to a char*, so when I port 
this to head, I hope to fix things in head by adding const rather than the 
quicker hack used here.  However, I did verify that in those places, we never 
try to alter the contents of "", so fortunately we don't trigger a segfault for 
trying to modify a read-only string.

2006-10-26  Eric Blake  <[email protected]>

	Silence -Wwrite-strings -Wpointer-arith warnings.
	* src/builtin.c (define_user_macro): Allow NULL argument.
	(m4_builtin, m4_indir): Cast away const of "".
	* src/format.c (format): Likewise.
	* src/macro.c (collect_arguments): Likewise.
	(expand_macro): Avoid math on void*.
	* src/m4.c (main): Adjust caller.
	* src/output.c (freeze_diversions): Detect off_t overflow.

Index: src/builtin.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/builtin.c,v
retrieving revision 1.1.1.1.2.45
diff -u -r1.1.1.1.2.45 builtin.c
--- src/builtin.c	19 Oct 2006 23:13:05 -0000	1.1.1.1.2.45
+++ src/builtin.c	26 Oct 2006 21:09:28 -0000
@@ -237,7 +237,7 @@
     free (SYMBOL_TEXT (s));
 
   SYMBOL_TYPE (s) = TOKEN_TEXT;
-  SYMBOL_TEXT (s) = xstrdup (text);
+  SYMBOL_TEXT (s) = xstrdup (text ? text : "");
 }
 
 /*-----------------------------------------------.
@@ -738,7 +738,7 @@
 	  if (TOKEN_DATA_TYPE (argv[i]) != TOKEN_TEXT)
 	    {
 	      TOKEN_DATA_TYPE (argv[i]) = TOKEN_TEXT;
-	      TOKEN_DATA_TEXT (argv[i]) = "";
+	      TOKEN_DATA_TEXT (argv[i]) = (char *) "";
 	    }
       bp->func (obs, argc - 1, argv + 1);
     }
@@ -779,7 +779,7 @@
 	  if (TOKEN_DATA_TYPE (argv[i]) != TOKEN_TEXT)
 	    {
 	      TOKEN_DATA_TYPE (argv[i]) = TOKEN_TEXT;
-	      TOKEN_DATA_TEXT (argv[i]) = "";
+	      TOKEN_DATA_TEXT (argv[i]) = (char *) "";
 	    }
       call_macro (s, argc - 1, argv + 1, obs);
     }
Index: src/format.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/format.c,v
retrieving revision 1.1.1.1.2.5
diff -u -r1.1.1.1.2.5 format.c
--- src/format.c	22 Jul 2006 21:43:27 -0000	1.1.1.1.2.5
+++ src/format.c	26 Oct 2006 21:09:28 -0000
@@ -77,7 +77,7 @@
   char *str;			/* malloc'd buffer of formatted text */
   enum {INT, UINT, LONG, ULONG, DOUBLE, STR} datatype;
 
-  fmt = ARG_STR (argc, argv);
+  fmt = (char *) ARG_STR (argc, argv);
   for (;;)
     {
       while ((c = *fmt++) != '%')
Index: src/m4.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/m4.c,v
retrieving revision 1.1.1.1.2.34
diff -u -r1.1.1.1.2.34 m4.c
--- src/m4.c	13 Oct 2006 22:25:32 -0000	1.1.1.1.2.34
+++ src/m4.c	26 Oct 2006 21:09:28 -0000
@@ -462,9 +462,7 @@
 	{
 	case 'D':
 	  macro_value = strchr (defines->macro, '=');
-	  if (macro_value == NULL)
-	    macro_value = "";
-	  else
+	  if (macro_value)
 	    *macro_value++ = '\0';
 	  define_user_macro (defines->macro, macro_value, SYMBOL_INSERT);
 	  break;
Index: src/macro.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/macro.c,v
retrieving revision 1.1.1.1.2.14
diff -u -r1.1.1.1.2.14 macro.c
--- src/macro.c	11 Oct 2006 17:07:03 -0000	1.1.1.1.2.14
+++ src/macro.c	26 Oct 2006 21:09:28 -0000
@@ -247,7 +247,7 @@
 	  if (!groks_macro_args && TOKEN_DATA_TYPE (&td) == TOKEN_FUNC)
 	    {
 	      TOKEN_DATA_TYPE (&td) = TOKEN_TEXT;
-	      TOKEN_DATA_TEXT (&td) = "";
+	      TOKEN_DATA_TEXT (&td) = (char *) "";
 	    }
 	  tdp = (token_data *) obstack_copy (arguments, &td, sizeof td);
 	  obstack_ptr_grow (argptr, tdp);
@@ -351,7 +351,7 @@
 
   argc = ((obstack_object_size (&argv_stack) - argv_base)
 	  / sizeof (token_data *));
-  argv = (token_data **) (obstack_base (&argv_stack) + argv_base);
+  argv = (token_data **) ((char *) obstack_base (&argv_stack) + argv_base);
 
   loc_close_file = current_file;
   loc_close_line = current_line;
Index: src/output.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/output.c,v
retrieving revision 1.1.1.1.2.12
diff -u -r1.1.1.1.2.12 output.c
--- src/output.c	26 Oct 2006 04:45:31 -0000	1.1.1.1.2.12
+++ src/output.c	26 Oct 2006 21:09:28 -0000
@@ -379,7 +379,7 @@
 		    current_line, output_current_line);
 #endif
 
-	    /* Output a `#line NUM' synchronisation directive if needed.
+	    /* Output a `#line NUM' synchronization directive if needed.
 	       If output_current_line was previously given a negative
 	       value (invalidated), rather output `#line NUM "FILE"'.  */
 
@@ -585,7 +585,11 @@
 	      fflush (diversion->file);
 	      if (fstat (fileno (diversion->file), &file_stat) < 0)
 		M4ERROR ((EXIT_FAILURE, errno, "cannot stat diversion"));
-	      fprintf (file, "D%d,%d", divnum, (int) file_stat.st_size);
+	      if (file_stat.st_size < 0
+		  || file_stat.st_size != (unsigned long) file_stat.st_size)
+		M4ERROR ((EXIT_FAILURE, 0, "diversion too large"));
+	      fprintf (file, "D%d,%lu", divnum,
+		       (unsigned long int) file_stat.st_size);
 	    }
 	  else
 	    fprintf (file, "D%d,%d\n", divnum, diversion->used);