head -dV option

Index: src/debug.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/debug.c,v
retrieving revision 1.1.1.1.2.8
diff -u -p -r1.1.1.1.2.8 debug.c
--- src/debug.c	18 Aug 2006 23:11:36 -0000	1.1.1.1.2.8
+++ src/debug.c	23 Aug 2006 00:45:06 -0000
@@ -219,8 +219,10 @@ debug_message_prefix (void)
     if (debug_level & DEBUG_TRACE_FILE)
       fprintf (debug, "%s:", current_file);
     if (debug_level & DEBUG_TRACE_LINE)
-      fprintf (debug, "%d:", current_line);
+      fprintf (debug, "%d: ", current_line);
   }
+  else
+    putc (' ', debug);
 }
 
 /* The rest of this file contains the functions for macro tracing output.
Index: src/input.c
===================================================================
RCS file: /sources/m4/m4/src/Attic/input.c,v
retrieving revision 1.1.1.1.2.20
diff -u -p -r1.1.1.1.2.20 input.c
--- src/input.c	18 Aug 2006 16:28:22 -0000	1.1.1.1.2.20
+++ src/input.c	23 Aug 2006 00:45:06 -0000
@@ -311,8 +311,13 @@ pop_input (void)
 
     case INPUT_FILE:
       if (debug_level & DEBUG_TRACE_INPUT)
-	DEBUG_MESSAGE2 ("input reverted to %s, line %d",
-			isp->u.u_f.name, isp->u.u_f.lineno);
+	{
+	  if (isp->u.u_f.lineno)
+	    DEBUG_MESSAGE2 ("input reverted to %s, line %d",
+			    isp->u.u_f.name, isp->u.u_f.lineno);
+	  else
+	    DEBUG_MESSAGE ("input exhausted");
+	}
 
       if (ferror (isp->u.u_f.file))
 	{

Index: doc/m4.texinfo
===================================================================
RCS file: /sources/m4/m4/doc/m4.texinfo,v
retrieving revision 1.31
diff -u -p -r1.31 m4.texinfo
--- doc/m4.texinfo	22 Aug 2006 13:44:22 -0000	1.31
+++ doc/m4.texinfo	23 Aug 2006 03:35:47 -0000
@@ -623,7 +623,10 @@ scripts.
 Set the debug-level according to the flags @var{FLAGS}.  The debug-level
 controls the format and amount of information presented by the debugging
 functions.  @xref{Debug Levels}, for more details on the format and
-meaning of @var{FLAGS}.  If omitted, @var{FLAGS} defaults to @samp{aeq}.
+meaning of @var{FLAGS}.  If omitted, @var{FLAGS} defaults to
+@samp{aeq}.  When the option is presented multiple times, if later
+@var{FLAGS} starts with @samp{-} or @samp{+}, they are cumulative,
+otherwise the later flags override all earlier occurrences.
 
 @item -l @var{NUM}
 @itemx --arglength=@var{NUM}
@@ -4006,15 +4009,15 @@ If you need to toggle sync lines on and 
 to insure that they are off or on, you may do so using
 @code{syncoutput}.
 
-@code{syncoutput(1)}, @code{syncoutput(on)}, and @code{syncoutput(yes)}
-causes @code{m4} to emit sync lines of the form: @code{#line <number>
-["<filename>"]}.
+If @var{truth} matches the extended regular expression
+@samp{^[1yY]|^([oO][nN])}, it causes @code{m4} to emit sync lines of the
+form: @code{#line <number> ["<file>"]}.
 
-@code{syncoutput(0)}, @code{syncoutput(off)}, and @code{syncoutput(no)}
-turn them off.
+If @var{truth} is empty, or matches the extended regular expression
+@samp{^[0nN]|^([oO][fF])}, it causes @code{m4} to turn sync lines off.
 
-All other arguments are ignored as is @code{syncoutput} without
-parenthesis.
+All other arguments are ignored and issue a warning.  The macro
+@code{syncoutput} is only recognized with arguments.
 @end deffn
 
 @node Frozen files
Index: m4/debug.c
===================================================================
RCS file: /sources/m4/m4/m4/debug.c,v
retrieving revision 1.22
diff -u -p -r1.22 debug.c
--- m4/debug.c	22 Aug 2006 22:36:28 -0000	1.22
+++ m4/debug.c	23 Aug 2006 03:35:47 -0000
@@ -29,14 +29,17 @@ static void set_debug_file (m4 *, FILE *
 /* Function to decode the debugging flags OPTS.  Used by main while
    processing option -d, and by the builtin debugmode ().  */
 int
-m4_debug_decode (m4 *context, const char *opts)
+m4_debug_decode (m4 *context, int previous, const char *opts)
 {
   int level;
+  char mode = '\0';
 
   if (opts == NULL || *opts == '\0')
     level = M4_DEBUG_TRACE_DEFAULT;
   else
     {
+      if (*opts == '-' || *opts == '+')
+	mode = *opts++;
       for (level = 0; *opts; opts++)
 	{
 	  switch (*opts)
@@ -97,6 +100,26 @@ m4_debug_decode (m4 *context, const char
   obstack_free (&context->trace_messages,
 		obstack_finish (&context->trace_messages));
 
+  switch (mode)
+    {
+    case '\0':
+      /* Replace old level.  */
+      break;
+
+    case '-':
+      /* Subtract flags.  */
+      level = previous & ~level;
+      break;
+
+    case '+':
+      /* Add flags.  */
+      level |= previous;
+      break;
+
+    default:
+      assert (!"INTERNAL ERROR: impossible mode from flags");
+    }
+
   return level;
 }
 
@@ -179,4 +202,5 @@ m4_debug_message_prefix (m4 *context)
       if (m4_is_debug_bit (context, M4_DEBUG_TRACE_LINE))
 	fprintf (debug_file, "%d:", m4_get_current_line (context));
     }
+  putc (' ', debug_file);
 }
Index: m4/input.c
===================================================================
RCS file: /sources/m4/m4/m4/input.c,v
retrieving revision 1.43
diff -u -p -r1.43 input.c
--- m4/input.c	16 Aug 2006 12:23:04 -0000	1.43
+++ m4/input.c	23 Aug 2006 03:35:48 -0000
@@ -223,8 +223,13 @@ static void
 file_clean (m4 *context)
 {
   if (m4_is_debug_bit (context, M4_DEBUG_TRACE_INPUT))
-    M4_DEBUG_MESSAGE2 (context, _("input reverted to %s, line %d"),
-		       isp->u.u_f.name, isp->u.u_f.lineno);
+    {
+      if (isp->u.u_f.lineno)
+	M4_DEBUG_MESSAGE2 (context, _("input reverted to %s, line %d"),
+			   isp->u.u_f.name, isp->u.u_f.lineno);
+      else
+	M4_DEBUG_MESSAGE (context, _("input exhausted"));
+    }
 
   fclose (isp->u.u_f.file);
   m4_set_current_file (context, isp->u.u_f.name);
Index: m4/m4module.h
===================================================================
RCS file: /sources/m4/m4/m4/m4module.h,v
retrieving revision 1.77
diff -u -p -r1.77 m4module.h
--- m4/m4module.h	9 Aug 2006 21:33:24 -0000	1.77
+++ m4/m4module.h	23 Aug 2006 03:35:48 -0000
@@ -268,7 +268,7 @@ enum {
   M4_DEBUG_TRACE_CALLID		= (1 << 9),
 
   /* V: very verbose --  print everything */
-  M4_DEBUG_TRACE_VERBOSE	= (~0)
+  M4_DEBUG_TRACE_VERBOSE	= ((1 << 10) - 1)
 };
 
 /* default flags -- equiv: aeq */
@@ -277,7 +277,7 @@ enum {
 
 #define m4_is_debug_bit(C,B)	(BIT_TEST (m4_get_debug_level_opt (C), (B)))
 
-extern int	m4_debug_decode		(m4 *, const char *);
+extern int	m4_debug_decode		(m4 *, int, const char *);
 extern bool	m4_debug_set_output	(m4 *, const char *);
 extern void	m4_debug_message_prefix (m4 *);
 
Index: modules/gnu.c
===================================================================
RCS file: /sources/m4/m4/modules/gnu.c,v
retrieving revision 1.49
diff -u -p -r1.49 gnu.c
--- modules/gnu.c	21 Aug 2006 12:46:24 -0000	1.49
+++ modules/gnu.c	23 Aug 2006 03:35:48 -0000
@@ -410,43 +410,17 @@ M4BUILTIN_HANDLER (debugmode)
 {
   int debug_level = m4_get_debug_level_opt (context);
   int new_debug_level;
-  int change_flag;
 
   if (argc == 1)
     m4_set_debug_level_opt (context, 0);
   else
     {
-      if (M4ARG (1)[0] == '+' || M4ARG (1)[0] == '-')
-	{
-	  change_flag = M4ARG (1)[0];
-	  new_debug_level = m4_debug_decode (context, M4ARG (1) + 1);
-	}
-      else
-	{
-	  change_flag = 0;
-	  new_debug_level = m4_debug_decode (context, M4ARG (1));
-	}
-
+      new_debug_level = m4_debug_decode (context, debug_level, M4ARG (1));
       if (new_debug_level < 0)
 	m4_error (context, 0, 0, _("%s: bad debug flags: `%s'"),
 		  M4ARG (0), M4ARG (1));
       else
-	{
-	  switch (change_flag)
-	    {
-	    case 0:
-	      m4_set_debug_level_opt (context, new_debug_level);
-	      break;
-
-	    case '+':
-	      m4_set_debug_level_opt (context, debug_level | new_debug_level);
-	      break;
-
-	    case '-':
-	      m4_set_debug_level_opt (context, debug_level & ~new_debug_level);
-	      break;
-	    }
-	}
+	m4_set_debug_level_opt (context, new_debug_level);
     }
 }
 
@@ -610,11 +584,11 @@ M4BUILTIN_HANDLER (regexp)
       if (resyntax < 0)
 	return;
     }
-  /*
-    else
-      regexp(VICTIM, REGEXP)  */
+  else
+    /* regexp(VICTIM, REGEXP)  */
+    replace = NULL;
 
-  buf = m4_regexp_compile (context, me, M4ARG (2), resyntax, argc == 3);
+  buf = m4_regexp_compile (context, me, M4ARG (2), resyntax, replace == NULL);
   if (!buf)
     return;
 
@@ -628,7 +602,7 @@ M4BUILTIN_HANDLER (regexp)
       return;
     }
 
-  if ((argc == 3) || (replace == NULL))
+  if (replace == NULL)
     m4_shipout_int (obs, startpos);
   else if (startpos >= 0)
     substitute (context, obs, me, M4ARG (1), replace, buf);
@@ -666,7 +640,7 @@ M4BUILTIN_HANDLER (renamesyms)
       replace = M4ARG (2);
 
       resyntax = m4_get_regexp_syntax_opt (context);
-      if (argc == 4)
+      if (argc >= 4)
 	{
 	  resyntax = m4_resyntax_encode_safe (context, me, M4ARG (3));
 	  if (resyntax < 0)
@@ -746,15 +720,22 @@ M4BUILTIN_HANDLER (symbols)
  **/
 M4BUILTIN_HANDLER (syncoutput)
 {
-  if (m4_is_symbol_value_text (argv[1]))
-    {
-      if (   M4ARG (1)[0] == '0'
-	  || M4ARG (1)[0] == 'n'
-	  || (M4ARG (1)[0] == 'o' && M4ARG (1)[1] == 'f'))
-	m4_set_sync_output_opt (context, false);
-      else if (   M4ARG (1)[0] == '1'
-	       || M4ARG (1)[0] == 'y'
-	       || (M4ARG (1)[0] == 'o' && M4ARG (1)[1] == 'n'))
-	m4_set_sync_output_opt (context, true);
-    }
+  const char *arg = M4ARG (1);
+
+  if (arg[0] == '\0'
+      || arg[0] == '0'
+      || arg[0] == 'n'
+      || arg[0] == 'N'
+      || ((arg[0] == 'o' || arg[0] == 'O')
+	  && (arg[1] == 'f' || arg[1] == 'F')))
+    m4_set_sync_output_opt (context, false);
+  else if (arg[0] == '1'
+	   || arg[0] == 'y'
+	   || arg[0] == 'Y'
+	   || ((arg[0] == 'o' || arg[0] == 'O')
+	       && (arg[1] == 'n' || arg[1] == 'N')))
+    m4_set_sync_output_opt (context, true);
+  else
+    m4_warn (context, 0, _("Warning: %s: unknown directive `%s'"),
+	     M4ARG (0), arg);
 }
Index: src/main.c
===================================================================
RCS file: /sources/m4/m4/src/main.c,v
retrieving revision 1.75
diff -u -p -r1.75 main.c
--- src/main.c	22 Aug 2006 16:16:48 -0000	1.75
+++ src/main.c	23 Aug 2006 03:35:48 -0000
@@ -345,7 +345,11 @@ main (int argc, char *const *argv, char 
 	break;
 
       case 'd':
-	m4_set_debug_level_opt (context, m4_debug_decode (context, optarg));
+	{
+	  int old = m4_get_debug_level_opt (context);
+	  m4_set_debug_level_opt (context, m4_debug_decode (context, old,
+							    optarg));
+	}
 	if (m4_get_debug_level_opt (context) < 0)
 	  {
 	    error (0, 0, _("bad debug flags: `%s'"), optarg);
Index: tests/options.at
===================================================================
RCS file: /sources/m4/m4/tests/options.at,v
retrieving revision 1.3
diff -u -p -r1.3 options.at
--- tests/options.at	22 Aug 2006 16:16:48 -0000	1.3
+++ tests/options.at	23 Aug 2006 03:35:48 -0000
@@ -73,3 +73,43 @@ OVERRIDE=It is changed.
 ]])
 
 AT_CLEANUP
+
+
+## ----------- ##
+## debug-flags ##
+## ----------- ##
+
+AT_SETUP([debug-flags])
+
+AT_DATA([[in]],
+[[divnum
+len(`abc')
+]])
+
+dnl AT_CHECK_M4 starts life with -d.  Make sure it looks like -daeq.
+AT_CHECK_M4([-tlen in], 0, [[0
+3
+]], [[m4trace: -1- len(`abc') -> `3'
+]])
+
+dnl Test all flags.
+AT_CHECK_M4([-dV in], 0, [[0
+3
+]], [[m4debug: input read from in
+m4trace:in:1: -1- id 1: divnum ...
+m4trace:in:1: -1- id 1: divnum -> ???
+m4trace:in:1: -1- id 1: divnum -> `0'
+m4trace:in:2: -1- id 2: len ...
+m4trace:in:2: -1- id 2: len(`abc') -> ???
+m4trace:in:2: -1- id 2: len(...) -> `3'
+m4debug:in:3: input exhausted
+]])
+
+dnl Test addition and subtraction of flags.
+AT_CHECK_M4([-d-e -d+xt in], 0, [[0
+3
+]], [[m4trace: -1- id 1: divnum
+m4trace: -1- id 2: len(`abc')
+]])
+
+AT_CLEANUP