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/* Command line option handling.

   Copyright (C) 2006, 2007, 2008 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "intl.h"

#include "coretypes.h"

#include "opts.h"

/* Perform a binary search to find which option the command-line INPUT

   matches.  Returns its index in the option array, and N_OPTS

   (cl_options_count) on failure.

   This routine is quite subtle.  A normal binary search is not good

   enough because some options can be suffixed with an argument, and

   multiple sub-matches can occur, e.g. input of "-pedantic" matching

   the initial substring of "-pedantic-errors".

   A more complicated example is -gstabs.  It should match "-g" with

   an argument of "stabs".  Suppose, however, that the number and list

   of switches are such that the binary search tests "-gen-decls"

   before having tested "-g".  This doesn't match, and as "-gen-decls"

   is less than "-gstabs", it will become the lower bound of the

   binary search range, and "-g" will never be seen.  To resolve this

   issue, 'optc-gen.awk' makes "-gen-decls" point, via the back_chain member,

   to "-g" so that failed searches that end between "-gen-decls" and

   the lexicographically subsequent switch know to go back and see if

   "-g" causes a match (which it does in this example).

   This search is done in such a way that the longest match for the

   front end in question wins.  If there is no match for the current

   front end, the longest match for a different front end is returned

   (or N_OPTS if none) and the caller emits an error message.  */

size_t

find_opt (const char *input, int lang_mask)

{

  size_t mn, mx, md, opt_len;

  size_t match_wrong_lang;

  int comp;

  mn = 0;

  mx = cl_options_count;

  /* Find mn such this lexicographical inequality holds:

     cl_options[mn] <= input < cl_options[mn + 1].  */

  while (mx - mn > 1)

    {

      md = (mn + mx) / 2;

      opt_len = cl_options[md].opt_len;

      comp = strncmp (input, cl_options[md].opt_text + 1, opt_len);

      if (comp < 0)

        mx = md;

      else

        mn = md;

    }

  /* This is the switch that is the best match but for a different

     front end, or cl_options_count if there is no match at all.  */

  match_wrong_lang = cl_options_count;

  /* Backtrace the chain of possible matches, returning the longest

     one, if any, that fits best.  With current GCC switches, this

     loop executes at most twice.  */

  do

    {

      const struct cl_option *opt = &cl_options[mn];

      /* Is the input either an exact match or a prefix that takes a

         joined argument?  */

      if (!strncmp (input, opt->opt_text + 1, opt->opt_len)

          && (input[opt->opt_len] == '\0' || (opt->flags & CL_JOINED)))

        {

          /* If language is OK, return it.  */

          if (opt->flags & lang_mask)

            return mn;

          /* If we haven't remembered a prior match, remember this

             one.  Any prior match is necessarily better.  */

          if (match_wrong_lang == cl_options_count)

            match_wrong_lang = mn;

        }

      /* Try the next possibility.  This is cl_options_count if there

         are no more.  */

      mn = opt->back_chain;

    }

  while (mn != cl_options_count);

  /* Return the best wrong match, or cl_options_count if none.  */

  return match_wrong_lang;

}

/* Return true if NEXT_OPT_IDX cancels OPT_IDX.  Return false if the

   next one is the same as ORIG_NEXT_OPT_IDX.  */

static bool

cancel_option (int opt_idx, int next_opt_idx, int orig_next_opt_idx)

{

  /* An option can be canceled by the same option or an option with

     Negative.  */

  if (cl_options [next_opt_idx].neg_index == opt_idx)

    return true;

  if (cl_options [next_opt_idx].neg_index != orig_next_opt_idx)

    return cancel_option (opt_idx, cl_options [next_opt_idx].neg_index,

                          orig_next_opt_idx);

  return false;

}

/* Filter out options canceled by the ones after them.  */

void

prune_options (int *argcp, char ***argvp)

{

  int argc = *argcp;

  int *options = XNEWVEC (int, argc);

  /* We will only return this replacement argv if we remove at least

     one argument, so it does not need to be size (argc + 1) to

     make room for the terminating NULL because we will always have

     freed up at least one slot when we end up using it at all.  */

  char **argv = XNEWVEC (char *, argc);

  int i, arg_count, need_prune = 0;

  const struct cl_option *option;

  size_t opt_index;

  /* Scan all arguments.  */

  for (i = 1; i < argc; i++)

    {

      int value = 1;

      const char *opt = (*argvp) [i];

      opt_index = find_opt (opt + 1, -1);

      if (opt_index == cl_options_count

          && (opt[1] == 'W' || opt[1] == 'f' || opt[1] == 'm')

          && opt[2] == 'n' && opt[3] == 'o' && opt[4] == '-')

        {

          char *dup;

          /* Drop the "no-" from negative switches.  */

          size_t len = strlen (opt) - 3;

          dup = XNEWVEC (char, len + 1);

          dup[0] = '-';

          dup[1] = opt[1];

          memcpy (dup + 2, opt + 5, len - 2 + 1);

          opt = dup;

          value = 0;

          opt_index = find_opt (opt + 1, -1);

          free (dup);

        }

      if (opt_index == cl_options_count)

        {

cont:

          options [i] = 0;

          continue;

        }

      option = &cl_options[opt_index];

      if (option->neg_index < 0)

        goto cont;

      /* Skip joined switches.  */

      if ((option->flags & CL_JOINED))

        goto cont;

      /* Reject negative form of switches that don't take negatives as

         unrecognized.  */

      if (!value && (option->flags & CL_REJECT_NEGATIVE))

        goto cont;

      options [i] = (int) opt_index;

      need_prune |= options [i];

    }

  if (!need_prune)

    goto done;

  /* Remove arguments which are negated by others after them.  */

  argv [0] = (*argvp) [0];

  arg_count = 1;

  for (i = 1; i < argc; i++)

    {

      int j, opt_idx;

      opt_idx = options [i];

      if (opt_idx)

        {

          int next_opt_idx;

          for (j = i + 1; j < argc; j++)

            {

              next_opt_idx = options [j];

              if (next_opt_idx

                  && cancel_option (opt_idx, next_opt_idx,

                                    next_opt_idx))

                break;

            }

        }

      else

        goto keep;

      if (j == argc)

        {

keep:

          argv [arg_count] = (*argvp) [i];

          arg_count++;

        }

    }

  if (arg_count != argc)

    {

      *argcp = arg_count;

      *argvp = argv;

      /* Add NULL-termination.  Guaranteed not to overflow because

         arg_count here can only be less than argc.  */

      argv[arg_count] = 0;

    }

  else

    {

done:

      free (argv);

    }

  free (options);

}