Constify strings in tracepoint.c, lookup_cmd and the completers.

This is sort of a continuation of Keith's parse_exp_1 constification
patch.  It started out by undoing these bits:

  @@ -754,9 +754,12 @@ validate_actionline (char **line, struct
   	  tmp_p = p;
   	  for (loc = t->base.loc; loc; loc = loc->next)
   	    {
  -	      p = tmp_p;
  -	      exp = parse_exp_1 (&p, loc->address,
  +	      const char *q;
  +
  +	      q = tmp_p;
  +	      exp = parse_exp_1 (&q, loc->address,
   				 block_for_pc (loc->address), 1);
  +	      p = (char *) q;

and progressively making more things const upwards, fixing fallout,
rinse repeat, until GDB built again (--enable-targets=all).

That ended up constifying lookup_cmd/add_cmd and (lots of) friends,
and the completers.

I didn't try to constify the command hooks themselves, because I know
upfront there are commands that write to the command string argument,
and I think I managed to stop at a nice non-hacky split point already.

I think the only non-really-super-obvious changes are
tracepoint.c:validate_actionline, and tracepoint.c:trace_dump_actions.

The rest is just mostly about 'char *' => 'const char *', 'char **'=>
'const char **', and the occasional (e.g., deprecated_cmd_warning)
case of 'char **'=> 'const char *', where/when I noticed that nothing
actually cares about the pointer to pointer output.

Tested on x86_64 Fedora 17, native and gdbserver.

gdb/
2013-03-13  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (struct add_partial_datum) <text, text0, word>: Make
	fields const.
	(ada_make_symbol_completion_list): Make "text0" parameter const.
	* ax-gdb.c (agent_eval_command_one): Make "exp" parameter const.
	* breakpoint.c (condition_completer): Make "text" and "word"
	parameters const.  Adjust.
	(check_tracepoint_command): Adjust to validate_actionline
	prototype change.
	(catch_syscall_completer): Make "text" and "word" parameters
	const.
	* cli/cli-cmds.c (show_user): Make "comname" local const.
	(valid_command_p): Make "command" parameter const.
	(alias_command): Make "alias_prefix" and "command_prefix" locals
	const.
	* cli/cli-decode.c (add_cmd): Make "name" parameter const.
	(add_alias_cmd): Make "name" and "oldname" parameters const.
	Adjust.  No longer make copy of OLDNAME.
	(add_prefix_cmd, add_abbrev_prefix_cmd, add_set_or_show_cmd)
	(add_setshow_cmd_full, add_setshow_enum_cmd)
	(add_setshow_auto_boolean_cmd, add_setshow_boolean_cmd)
	(add_setshow_filename_cmd, add_setshow_string_cmd)
	(add_setshow_string_noescape_cmd)
	(add_setshow_optional_filename_cmd, add_setshow_integer_cmd)
	(add_setshow_uinteger_cmd, add_setshow_zinteger_cmd)
	(add_setshow_zuinteger_unlimited_cmd, add_setshow_zuinteger_cmd)
	(delete_cmd, add_info, add_info_alias, add_com, add_com_alias):
	Make "name" parameter const.
	(help_cmd): Rename "command" parameter to "arg".  New const local
	"command".
	(find_cmd): Make "command" parameter const.
	(lookup_cmd_1): Make "text" parameter pointer to const.  Adjust to
	deprecated_cmd_warning prototype change.
	(undef_cmd_error): Make "cmdtype" parameter const.
	(lookup_cmd): Make "line" parameter const.
	(deprecated_cmd_warning): Change type of "text" parameter to
	pointer to const char, from pointer to pointer to char.  Adjust.
	(lookup_cmd_composition): Make "text" parameter const.
	(complete_on_cmdlist, complete_on_enum): Make "text" and "word"
	parameters const.
	* cli/cli-decode.h (struct cmd_list_element) <name>: Make field
	const.
	* cli/cli-script.c (validate_comname): Make "tem" local const.
	(define_command): New const local "tem_c".  Use it in calls to
	lookup_cmd.
	(document_command): Make "tem" and "comfull" locals const.
	(show_user_1): Make "prefix" and "name" parameters const.
	* cli-script.h (show_user_1): Make "prefix" and "name" parameters
	const.
	* command.h (add_cmd, add_alias_cmd, add_prefix_cmd)
	(add_abbrev_prefix_cmd, completer_ftype, lookup_cmd, lookup_cmd_1)
	(deprecated_cmd_warning, lookup_cmd_composition, add_com)
	(add_com_alias, add_info, add_info_alias, complete_on_cmdlist)
	(complete_on_enum, add_setshow_enum_cmd)
	(add_setshow_auto_boolean_cmd, add_setshow_boolean_cmd)
	(add_setshow_filename_cmd, add_setshow_string_cmd)
	(add_setshow_string_noescape_cmd)
	(add_setshow_optional_filename_cmd, add_setshow_integer_cmd)
	(add_setshow_uinteger_cmd, add_setshow_zinteger_cmd)
	(add_setshow_zuinteger_cmd, add_setshow_zuinteger_unlimited_cmd):
	Change prototypes, constifying strings.
	* completer.c (noop_completer, filename_completer): Make "text"
	and "prefix" parameters const.
	(location_completer, expression_completer)
	(complete_line_internal): Make "text" and "prefix" parameters
	const and adjust.
	(command_completer, signal_completer): Make "text" and "prefix"
	parameters const.
	* completer.h (noop_completer, filename_completer)
	(expression_completer, location_completer, command_completer)
	(signal_completer): Change prototypes.
	* corefile.c (complete_set_gnutarget): Make "text" and "word"
	parameters const.
	* cp-abi.c (cp_abi_completer): Likewise.
	* expression.h (parse_expression_for_completion): Change
	prototype.
	* f-lang.c (f_make_symbol_completion_list): Make "text" and "word"
	parameters const.
	* infcmd.c (_initialize_infcmd): Make "cmd_name" local const.
	* infrun.c (handle_completer): Make "text" and "word" parameters
	const.
	* interps.c (interpreter_completer): Make "text" and "word"
	parameters const.
	* language.h (struct language_defn)
	<la_make_symbol_completion_list>: Make "text" and "word"
	parameters const.
	* parse.c (parse_exp_1): Move const hack to parse_exp_in_context.
	(parse_exp_in_context): Rename to ...
	(parse_exp_in_context_1): ... this.
	(parse_exp_in_context): Reimplement, with const hack from
	parse_exp_1.
	(parse_expression_for_completion): Make "string" parameter const.
	* printcmd.c (decode_format): Make "string_ptr" parameter pointer
	to pointer to const char.  Adjust.
	(print_command_1): Make "exp" parameter const.
	(output_command): Rename to ...
	(output_command_const): ... this.  Make "exp" parameter const.
	(output_command): Reimplement.
	(x_command): Adjust.
	(display_command): Rename "exp" parameter to "arg".  New "exp"
	local, const version of "arg".
	* python/py-auto-load.c (gdbpy_initialize_auto_load): Make
	"cmd_name" local const.
	* python/py-cmd.c (cmdpy_destroyer): Cast const away in xfree
	call.
	(cmdpy_completer): Make "text" and "word" parameters const.
	(gdbpy_parse_command_name): Make "prefix_text2" local const.
	* python/py-param.c (add_setshow_generic): Make "tmp_name" local
	const.
	* remote.c (_initialize_remote): Make "cmd_name" local const.
	* symtab.c (language_search_unquoted_string): Make "text" and "p"
	parameters const.  Adjust.
	(completion_list_add_fields): Make "sym_text", "text" and "word"
	parameters const.
	(struct add_name_data) <sym_text, text, word>: Make fields const.
	(default_make_symbol_completion_list_break_on): Make "text" and
	"word" parameters const.  Adjust locals.
	(default_make_symbol_completion_list)
	(make_symbol_completion_list, make_symbol_completion_type)
	(make_symbol_completion_list_fn): Make "text" and "word"
	parameters const.
	(make_file_symbol_completion_list): Make "text", "word" and
	"srcfile" parameters const.  Adjust locals.
	(add_filename_to_list): Make "text" and "word" parameters const.
	(struct add_partial_filename_data) <text, word>: Make fields
	const.
	(make_source_files_completion_list): Make "text" and "word"
	parameters const.
	* symtab.h (default_make_symbol_completion_list_break_on)
	(default_make_symbol_completion_list, make_symbol_completion_list)
	(make_symbol_completion_type enum type_code)
	(make_symbol_completion_list_fn make_file_symbol_completion_list)
	(make_source_files_completion_list): Change prototype.
	* top.c (execute_command): Adjust to pass pointer to pointer to
	const char to lookup_cmd, and to deprecated_cmd_warning prototype
	change.
	(set_verbose): Make "cmdname" local const.
	* tracepoint.c (decode_agent_options): Make "exp" parameter const,
	and adjust.
	(validate_actionline): Make "line" parameter a pointer to const
	char, and adjust.
	(encode_actions_1): Make "action_exp" local const, and adjust.
	(encode_actions): Adjust.
	(replace_comma): Delete.
	(trace_dump_actions): Make "action_exp" and "next_comma" locals
	const, and adjust.  Don't frob the action string while splitting
	it at commas.  Instead, make a copy of each split substring in
	turn.
	(trace_dump_command): Adjust to validate_actionline prototype
	change.
	* tracepoint.h (decode_agent_options, decode_agent_options)
	(encode_actions, validate_actionline): Change prototypes.
	* valprint.h (output_command): Delete declaration.
	(output_command_const): Declare.
	* value.c (function_destroyer): Cast const away in xfree call.

1 files changed, 57 insertions, 65 deletions

diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index 513dccc..4db93ca 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -610,8 +610,8 @@ teval_pseudocommand (char *args, int from_tty)
 
 /* Parse any collection options, such as /s for strings.  */
 
-char *
-decode_agent_options (char *exp)
+const char *
+decode_agent_options (const char *exp)
 {
   struct value_print_options opts;
 
@@ -643,7 +643,7 @@ decode_agent_options (char *exp)
   else
     error (_("Undefined collection format \"%c\"."), *exp);
 
-  exp = skip_spaces (exp);
+  exp = skip_spaces_const (exp);
 
   return exp;
 }
@@ -700,21 +700,22 @@ report_agent_reqs_errors (struct agent_expr *aexpr)
 
 /* worker function */
 void
-validate_actionline (char **line, struct breakpoint *b)
+validate_actionline (const char *line, struct breakpoint *b)
 {
   struct cmd_list_element *c;
   struct expression *exp = NULL;
   struct cleanup *old_chain = NULL;
-  char *p, *tmp_p;
+  const char *tmp_p;
+  const char *p;
   struct bp_location *loc;
   struct agent_expr *aexpr;
   struct tracepoint *t = (struct tracepoint *) b;
 
   /* If EOF is typed, *line is NULL.  */
-  if (*line == NULL)
+  if (line == NULL)
     return;
 
-  p = skip_spaces (*line);
+  p = skip_spaces_const (line);
 
   /* Symbol lookup etc.  */
   if (*p == '\0')	/* empty line: just prompt for another line.  */
@@ -736,7 +737,7 @@ validate_actionline (char **line, struct breakpoint *b)
       do
 	{			/* Repeat over a comma-separated list.  */
 	  QUIT;			/* Allow user to bail out with ^C.  */
-	  p = skip_spaces (p);
+	  p = skip_spaces_const (p);
 
 	  if (*p == '$')	/* Look for special pseudo-symbols.  */
 	    {
@@ -754,12 +755,9 @@ validate_actionline (char **line, struct breakpoint *b)
 	  tmp_p = p;
 	  for (loc = t->base.loc; loc; loc = loc->next)
 	    {
-	      const char *q;
-
-	      q = tmp_p;
-	      exp = parse_exp_1 (&q, loc->address,
+	      p = tmp_p;
+	      exp = parse_exp_1 (&p, loc->address,
 				 block_for_pc (loc->address), 1);
-	      p = (char *) q;
 	      old_chain = make_cleanup (free_current_contents, &exp);
 
 	      if (exp->elts[0].opcode == OP_VAR_VALUE)
@@ -804,18 +802,16 @@ validate_actionline (char **line, struct breakpoint *b)
       do
 	{			/* Repeat over a comma-separated list.  */
 	  QUIT;			/* Allow user to bail out with ^C.  */
-	  p = skip_spaces (p);
+	  p = skip_spaces_const (p);
 
 	  tmp_p = p;
 	  for (loc = t->base.loc; loc; loc = loc->next)
 	    {
-	      const char *q;
+	      p = tmp_p;
 
-	      q = tmp_p;
 	      /* Only expressions are allowed for this action.  */
-	      exp = parse_exp_1 (&q, loc->address,
+	      exp = parse_exp_1 (&p, loc->address,
 				 block_for_pc (loc->address), 1);
-	      p = (char *) q;
 	      old_chain = make_cleanup (free_current_contents, &exp);
 
 	      /* We have something to evaluate, make sure that the expr to
@@ -838,20 +834,20 @@ validate_actionline (char **line, struct breakpoint *b)
 
   else if (cmd_cfunc_eq (c, while_stepping_pseudocommand))
     {
-      char *steparg;		/* In case warning is necessary.  */
-
-      p = skip_spaces (p);
-      steparg = p;
+      char *endp;
 
-      if (*p == '\0' || (t->step_count = strtol (p, &p, 0)) == 0)
-	error (_("while-stepping step count `%s' is malformed."), *line);
+      p = skip_spaces_const (p);
+      t->step_count = strtol (p, &endp, 0);
+      if (endp == p || t->step_count == 0)
+	error (_("while-stepping step count `%s' is malformed."), line);
+      p = endp;
     }
 
   else if (cmd_cfunc_eq (c, end_actions_pseudocommand))
     ;
 
   else
-    error (_("`%s' is not a supported tracepoint action."), *line);
+    error (_("`%s' is not a supported tracepoint action."), line);
 }
 
 enum {
@@ -1375,7 +1371,7 @@ encode_actions_1 (struct command_line *action,
 		  struct collection_list *collect,
 		  struct collection_list *stepping_list)
 {
-  char *action_exp;
+  const char *action_exp;
   struct expression *exp = NULL;
   int i;
   struct value *tempval;
@@ -1386,7 +1382,7 @@ encode_actions_1 (struct command_line *action,
     {
       QUIT;			/* Allow user to bail out with ^C.  */
       action_exp = action->line;
-      action_exp = skip_spaces (action_exp);
+      action_exp = skip_spaces_const (action_exp);
 
       cmd = lookup_cmd (&action_exp, cmdlist, "", -1, 1);
       if (cmd == 0)
@@ -1401,7 +1397,7 @@ encode_actions_1 (struct command_line *action,
 	  do
 	    {			/* Repeat over a comma-separated list.  */
 	      QUIT;		/* Allow user to bail out with ^C.  */
-	      action_exp = skip_spaces (action_exp);
+	      action_exp = skip_spaces_const (action_exp);
 
 	      if (0 == strncasecmp ("$reg", action_exp, 4))
 		{
@@ -1476,12 +1472,9 @@ encode_actions_1 (struct command_line *action,
 		  unsigned long addr;
 		  struct cleanup *old_chain = NULL;
 		  struct cleanup *old_chain1 = NULL;
-		  const char *q;
 
-		  q = action_exp;
-		  exp = parse_exp_1 (&q, tloc->address,
+		  exp = parse_exp_1 (&action_exp, tloc->address,
 				     block_for_pc (tloc->address), 1);
-		  action_exp = (char *) q;
 		  old_chain = make_cleanup (free_current_contents, &exp);
 
 		  switch (exp->elts[0].opcode)
@@ -1565,17 +1558,14 @@ encode_actions_1 (struct command_line *action,
 	  do
 	    {			/* Repeat over a comma-separated list.  */
 	      QUIT;		/* Allow user to bail out with ^C.  */
-	      action_exp = skip_spaces (action_exp);
+	      action_exp = skip_spaces_const (action_exp);
 
 		{
 		  struct cleanup *old_chain = NULL;
 		  struct cleanup *old_chain1 = NULL;
-		  const char *q;
 
-		  q = action_exp;
-		  exp = parse_exp_1 (&q, tloc->address,
+		  exp = parse_exp_1 (&action_exp, tloc->address,
 				     block_for_pc (tloc->address), 1);
-		  action_exp = (char *) q;
 		  old_chain = make_cleanup (free_current_contents, &exp);
 
 		  aexpr = gen_eval_for_expr (tloc->address, exp);
@@ -1643,18 +1633,15 @@ encode_actions (struct breakpoint *t, struct bp_location *tloc,
      the fly, and don't cache it.  */
   if (*default_collect)
     {
-      char *line;
-
       default_collect_line =  xstrprintf ("collect %s", default_collect);
       make_cleanup (xfree, default_collect_line);
 
-      line = default_collect_line;
-      validate_actionline (&line, t);
+      validate_actionline (default_collect_line, t);
 
       default_collect_action = xmalloc (sizeof (struct command_line));
       make_cleanup (xfree, default_collect_action);
       default_collect_action->next = actions;
-      default_collect_action->line = line;
+      default_collect_action->line = default_collect_line;
       actions = default_collect_action;
     }
   encode_actions_1 (actions, t, tloc, frame_reg, frame_offset,
@@ -2800,15 +2787,6 @@ scope_info (char *args, int from_tty)
 		     save_args);
 }
 
-/* worker function (cleanup) */
-static void
-replace_comma (void *data)
-{
-  char *comma = data;
-  *comma = ',';
-}
-
-
 /* Helper for trace_dump_command.  Dump the action list starting at
    ACTION.  STEPPING_ACTIONS is true if we're iterating over the
    actions of the body of a while-stepping action.  STEPPING_FRAME is
@@ -2820,7 +2798,7 @@ trace_dump_actions (struct command_line *action,
 		    int stepping_actions, int stepping_frame,
 		    int from_tty)
 {
-  char *action_exp, *next_comma;
+  const char *action_exp, *next_comma;
 
   for (; action != NULL; action = action->next)
     {
@@ -2828,7 +2806,7 @@ trace_dump_actions (struct command_line *action,
 
       QUIT;			/* Allow user to bail out with ^C.  */
       action_exp = action->line;
-      action_exp = skip_spaces (action_exp);
+      action_exp = skip_spaces_const (action_exp);
 
       /* The collection actions to be done while stepping are
          bracketed by the commands "while-stepping" and "end".  */
@@ -2858,6 +2836,10 @@ trace_dump_actions (struct command_line *action,
 	     STEPPING_ACTIONS should be equal.  */
 	  if (stepping_frame == stepping_actions)
 	    {
+	      char *cmd = NULL;
+	      struct cleanup *old_chain
+		= make_cleanup (free_current_contents, &cmd);
+
 	      if (*action_exp == '/')
 		action_exp = decode_agent_options (action_exp);
 
@@ -2866,7 +2848,7 @@ trace_dump_actions (struct command_line *action,
 		  QUIT;		/* Allow user to bail out with ^C.  */
 		  if (*action_exp == ',')
 		    action_exp++;
-		  action_exp = skip_spaces (action_exp);
+		  action_exp = skip_spaces_const (action_exp);
 
 		  next_comma = strchr (action_exp, ',');
 
@@ -2880,20 +2862,31 @@ trace_dump_actions (struct command_line *action,
 		    args_info (NULL, from_tty);
 		  else
 		    {		/* variable */
-		      if (next_comma)
+		      if (next_comma != NULL)
 			{
-			  make_cleanup (replace_comma, next_comma);
-			  *next_comma = '\0';
+			  size_t len = next_comma - action_exp;
+
+			  cmd = xrealloc (cmd, len + 1);
+			  memcpy (cmd, action_exp, len);
+			  cmd[len] = 0;
+			}
+		      else
+			{
+			  size_t len = strlen (action_exp);
+
+			  cmd = xrealloc (cmd, len + 1);
+			  memcpy (cmd, action_exp, len + 1);
 			}
-		      printf_filtered ("%s = ", action_exp);
-		      output_command (action_exp, from_tty);
+
+		      printf_filtered ("%s = ", cmd);
+		      output_command_const (cmd, from_tty);
 		      printf_filtered ("\n");
 		    }
-		  if (next_comma)
-		    *next_comma = ',';
 		  action_exp = next_comma;
 		}
 	      while (action_exp && *action_exp == ',');
+
+	      do_cleanups (old_chain);
 	    }
 	}
     }
@@ -2908,7 +2901,7 @@ trace_dump_command (char *args, int from_tty)
   struct tracepoint *t;
   int stepping_frame = 0;
   struct bp_location *loc;
-  char *line, *default_collect_line = NULL;
+  char *default_collect_line = NULL;
   struct command_line *actions, *default_collect_action = NULL;
   struct cleanup *old_chain = NULL;
 
@@ -2952,12 +2945,11 @@ trace_dump_command (char *args, int from_tty)
     {
       default_collect_line = xstrprintf ("collect %s", default_collect);
       old_chain = make_cleanup (xfree, default_collect_line);
-      line = default_collect_line;
-      validate_actionline (&line, &t->base);
+      validate_actionline (default_collect_line, &t->base);
       default_collect_action = xmalloc (sizeof (struct command_line));
       make_cleanup (xfree, default_collect_action);
       default_collect_action->next = actions;
-      default_collect_action->line = line;
+      default_collect_action->line = default_collect_line;
       actions = default_collect_action;
     }