/* Deal with I/O statements & related stuff.
   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
   2009, 2010, 2011
   Free Software Foundation, Inc.
   Contributed by Andy Vaught

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 "flags.h"
#include "gfortran.h"
#include "match.h"
#include "parse.h"

gfc_st_label
format_asterisk = {0, NULL, NULL, -1, ST_LABEL_FORMAT, ST_LABEL_FORMAT, NULL,
		   0, {NULL, NULL}};

typedef struct
{
  const char *name, *spec, *value;
  bt type;
}
io_tag;

static const io_tag
	tag_file	= {"FILE", " file =", " %e", BT_CHARACTER },
	tag_status	= {"STATUS", " status =", " %e", BT_CHARACTER},
	tag_e_access	= {"ACCESS", " access =", " %e", BT_CHARACTER},
	tag_e_form	= {"FORM", " form =", " %e", BT_CHARACTER},
	tag_e_recl	= {"RECL", " recl =", " %e", BT_INTEGER},
	tag_e_blank	= {"BLANK", " blank =", " %e", BT_CHARACTER},
	tag_e_position	= {"POSITION", " position =", " %e", BT_CHARACTER},
	tag_e_action	= {"ACTION", " action =", " %e", BT_CHARACTER},
	tag_e_delim	= {"DELIM", " delim =", " %e", BT_CHARACTER},
	tag_e_pad	= {"PAD", " pad =", " %e", BT_CHARACTER},
	tag_e_decimal	= {"DECIMAL", " decimal =", " %e", BT_CHARACTER},
	tag_e_encoding	= {"ENCODING", " encoding =", " %e", BT_CHARACTER},
	tag_e_async	= {"ASYNCHRONOUS", " asynchronous =", " %e", BT_CHARACTER},
	tag_e_round	= {"ROUND", " round =", " %e", BT_CHARACTER},
	tag_e_sign	= {"SIGN", " sign =", " %e", BT_CHARACTER},
	tag_unit	= {"UNIT", " unit =", " %e", BT_INTEGER},
	tag_advance	= {"ADVANCE", " advance =", " %e", BT_CHARACTER},
	tag_rec		= {"REC", " rec =", " %e", BT_INTEGER},
	tag_spos	= {"POSITION", " pos =", " %e", BT_INTEGER},
	tag_format	= {"FORMAT", NULL, NULL, BT_CHARACTER},
	tag_iomsg	= {"IOMSG", " iomsg =", " %e", BT_CHARACTER},
	tag_iostat	= {"IOSTAT", " iostat =", " %v", BT_INTEGER},
	tag_size	= {"SIZE", " size =", " %v", BT_INTEGER},
	tag_exist	= {"EXIST", " exist =", " %v", BT_LOGICAL},
	tag_opened	= {"OPENED", " opened =", " %v", BT_LOGICAL},
	tag_named	= {"NAMED", " named =", " %v", BT_LOGICAL},
	tag_name	= {"NAME", " name =", " %v", BT_CHARACTER},
	tag_number	= {"NUMBER", " number =", " %v", BT_INTEGER},
	tag_s_access	= {"ACCESS", " access =", " %v", BT_CHARACTER},
	tag_sequential	= {"SEQUENTIAL", " sequential =", " %v", BT_CHARACTER},
	tag_direct	= {"DIRECT", " direct =", " %v", BT_CHARACTER},
	tag_s_form	= {"FORM", " form =", " %v", BT_CHARACTER},
	tag_formatted	= {"FORMATTED", " formatted =", " %v", BT_CHARACTER},
	tag_unformatted	= {"UNFORMATTED", " unformatted =", " %v", BT_CHARACTER},
	tag_s_recl	= {"RECL", " recl =", " %v", BT_INTEGER},
	tag_nextrec	= {"NEXTREC", " nextrec =", " %v", BT_INTEGER},
	tag_s_blank	= {"BLANK", " blank =", " %v", BT_CHARACTER},
	tag_s_position	= {"POSITION", " position =", " %v", BT_CHARACTER},
	tag_s_action	= {"ACTION", " action =", " %v", BT_CHARACTER},
	tag_read	= {"READ", " read =", " %v", BT_CHARACTER},
	tag_write	= {"WRITE", " write =", " %v", BT_CHARACTER},
	tag_readwrite	= {"READWRITE", " readwrite =", " %v", BT_CHARACTER},
	tag_s_delim	= {"DELIM", " delim =", " %v", BT_CHARACTER},
	tag_s_pad	= {"PAD", " pad =", " %v", BT_CHARACTER},
	tag_s_decimal	= {"DECIMAL", " decimal =", " %v", BT_CHARACTER},
	tag_s_encoding	= {"ENCODING", " encoding =", " %v", BT_CHARACTER},
	tag_s_async	= {"ASYNCHRONOUS", " asynchronous =", " %v", BT_CHARACTER},
	tag_s_round	= {"ROUND", " round =", " %v", BT_CHARACTER},
	tag_s_sign	= {"SIGN", " sign =", " %v", BT_CHARACTER},
	tag_iolength	= {"IOLENGTH", " iolength =", " %v", BT_INTEGER},
	tag_convert     = {"CONVERT", " convert =", " %e", BT_CHARACTER},
	tag_strm_out    = {"POS", " pos =", " %v", BT_INTEGER},
	tag_err		= {"ERR", " err =", " %l", BT_UNKNOWN},
	tag_end		= {"END", " end =", " %l", BT_UNKNOWN},
	tag_eor		= {"EOR", " eor =", " %l", BT_UNKNOWN},
	tag_id		= {"ID", " id =", " %v", BT_INTEGER},
	tag_pending	= {"PENDING", " pending =", " %v", BT_LOGICAL},
	tag_newunit	= {"NEWUNIT", " newunit =", " %v", BT_INTEGER};

static gfc_dt *current_dt;

#define RESOLVE_TAG(x, y) if (resolve_tag(x, y) == FAILURE) return FAILURE;


/**************** Fortran 95 FORMAT parser  *****************/

/* FORMAT tokens returned by format_lex().  */
typedef enum
{
  FMT_NONE, FMT_UNKNOWN, FMT_SIGNED_INT, FMT_ZERO, FMT_POSINT, FMT_PERIOD,
  FMT_COMMA, FMT_COLON, FMT_SLASH, FMT_DOLLAR, FMT_LPAREN,
  FMT_RPAREN, FMT_X, FMT_SIGN, FMT_BLANK, FMT_CHAR, FMT_P, FMT_IBOZ, FMT_F,
  FMT_E, FMT_EN, FMT_ES, FMT_G, FMT_L, FMT_A, FMT_D, FMT_H, FMT_END,
  FMT_ERROR, FMT_DC, FMT_DP, FMT_T, FMT_TR, FMT_TL, FMT_STAR, FMT_RC,
  FMT_RD, FMT_RN, FMT_RP, FMT_RU, FMT_RZ
}
format_token;

/* Local variables for checking format strings.  The saved_token is
   used to back up by a single format token during the parsing
   process.  */
static gfc_char_t *format_string;
static int format_string_pos;
static int format_length, use_last_char;
static char error_element;
static locus format_locus;

static format_token saved_token;

static enum
{ MODE_STRING, MODE_FORMAT, MODE_COPY }
mode;


/* Return the next character in the format string.  */

static char
next_char (gfc_instring in_string)
{
  static gfc_char_t c;

  if (use_last_char)
    {
      use_last_char = 0;
      return c;
    }

  format_length++;

  if (mode == MODE_STRING)
    c = *format_string++;
  else
    {
      c = gfc_next_char_literal (in_string);
      if (c == '\n')
	c = '\0';
    }

  if (gfc_option.flag_backslash && c == '\\')
    {
      locus old_locus = gfc_current_locus;

      if (gfc_match_special_char (&c) == MATCH_NO)
	gfc_current_locus = old_locus;

      if (!(gfc_option.allow_std & GFC_STD_GNU) && !inhibit_warnings)
	gfc_warning ("Extension: backslash character at %C");
    }

  if (mode == MODE_COPY)
    *format_string++ = c;

  if (mode != MODE_STRING)
    format_locus = gfc_current_locus;

  format_string_pos++;

  c = gfc_wide_toupper (c);
  return c;
}


/* Back up one character position.  Only works once.  */

static void
unget_char (void)
{
  use_last_char = 1;
}

/* Eat up the spaces and return a character.  */

static char
next_char_not_space (bool *error)
{
  char c;
  do
    {
      error_element = c = next_char (NONSTRING);
      if (c == '\t')
	{
	  if (gfc_option.allow_std & GFC_STD_GNU)
	    gfc_warning ("Extension: Tab character in format at %C");
	  else
	    {
	      gfc_error ("Extension: Tab character in format at %C");
	      *error = true;
	      return c;
	    }
	}
    }
  while (gfc_is_whitespace (c));
  return c;
}

static int value = 0;

/* Simple lexical analyzer for getting the next token in a FORMAT
   statement.  */

static format_token
format_lex (void)
{
  format_token token;
  char c, delim;
  int zflag;
  int negative_flag;
  bool error = false;

  if (saved_token != FMT_NONE)
    {
      token = saved_token;
      saved_token = FMT_NONE;
      return token;
    }

  c = next_char_not_space (&error);
  
  negative_flag = 0;
  switch (c)
    {
    case '-':
      negative_flag = 1;
    case '+':
      c = next_char_not_space (&error);
      if (!ISDIGIT (c))
	{
	  token = FMT_UNKNOWN;
	  break;
	}

      value = c - '0';

      do
	{
	  c = next_char_not_space (&error);
	  if (ISDIGIT (c))
	    value = 10 * value + c - '0';
	}
      while (ISDIGIT (c));

      unget_char ();

      if (negative_flag)
	value = -value;

      token = FMT_SIGNED_INT;
      break;

    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      zflag = (c == '0');

      value = c - '0';

      do
	{
	  c = next_char_not_space (&error);
	  if (ISDIGIT (c))
	    {
	      value = 10 * value + c - '0';
	      if (c != '0')
		zflag = 0;
	    }
	}
      while (ISDIGIT (c));

      unget_char ();
      token = zflag ? FMT_ZERO : FMT_POSINT;
      break;

    case '.':
      token = FMT_PERIOD;
      break;

    case ',':
      token = FMT_COMMA;
      break;

    case ':':
      token = FMT_COLON;
      break;

    case '/':
      token = FMT_SLASH;
      break;

    case '$':
      token = FMT_DOLLAR;
      break;

    case 'T':
      c = next_char_not_space (&error);
      switch (c)
	{
	case 'L':
	  token = FMT_TL;
	  break;
	case 'R':
	  token = FMT_TR;
	  break;
	default:
	  token = FMT_T;
	  unget_char ();
	}
      break;

    case '(':
      token = FMT_LPAREN;
      break;

    case ')':
      token = FMT_RPAREN;
      break;

    case 'X':
      token = FMT_X;
      break;

    case 'S':
      c = next_char_not_space (&error);
      if (c != 'P' && c != 'S')
	unget_char ();

      token = FMT_SIGN;
      break;

    case 'B':
      c = next_char_not_space (&error);
      if (c == 'N' || c == 'Z')
	token = FMT_BLANK;
      else
	{
	  unget_char ();
	  token = FMT_IBOZ;
	}

      break;

    case '\'':
    case '"':
      delim = c;

      value = 0;

      for (;;)
	{
	  c = next_char (INSTRING_WARN);
	  if (c == '\0')
	    {
	      token = FMT_END;
	      break;
	    }

	  if (c == delim)
	    {
	      c = next_char (INSTRING_NOWARN);

	      if (c == '\0')
		{
		  token = FMT_END;
		  break;
		}

	      if (c != delim)
		{
		  unget_char ();
		  token = FMT_CHAR;
		  break;
		}
	    }
	  value++;
	}
      break;

    case 'P':
      token = FMT_P;
      break;

    case 'I':
    case 'O':
    case 'Z':
      token = FMT_IBOZ;
      break;

    case 'F':
      token = FMT_F;
      break;

    case 'E':
      c = next_char_not_space (&error);
      if (c == 'N' )
	token = FMT_EN;
      else if (c == 'S')
        token = FMT_ES;
      else
	{
	  token = FMT_E;
	  unget_char ();
	}

      break;

    case 'G':
      token = FMT_G;
      break;

    case 'H':
      token = FMT_H;
      break;

    case 'L':
      token = FMT_L;
      break;

    case 'A':
      token = FMT_A;
      break;

    case 'D':
      c = next_char_not_space (&error);
      if (c == 'P')
	{
	  if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DP format "
	      "specifier not allowed at %C") == FAILURE)
	    return FMT_ERROR;
	  token = FMT_DP;
	}
      else if (c == 'C')
	{
	  if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DC format "
	      "specifier not allowed at %C") == FAILURE)
	    return FMT_ERROR;
	  token = FMT_DC;
	}
      else
	{
	  token = FMT_D;
	  unget_char ();
	}
      break;

    case 'R':
      c = next_char_not_space (&error);
      switch (c)
	{
	case 'C':
	  token = FMT_RC;
	  break;
	case 'D':
	  token = FMT_RD;
	  break;
	case 'N':
	  token = FMT_RN;
	  break;
	case 'P':
	  token = FMT_RP;
	  break;
	case 'U':
	  token = FMT_RU;
	  break;
	case 'Z':
	  token = FMT_RZ;
	  break;
	default:
	  token = FMT_UNKNOWN;
	  unget_char ();
	  break;
	}
      break;

    case '\0':
      token = FMT_END;
      break;

    case '*':
      token = FMT_STAR;
      break;

    default:
      token = FMT_UNKNOWN;
      break;
    }

  if (error)
    return FMT_ERROR;

  return token;
}


static const char *
token_to_string (format_token t)
{
  switch (t)
    {
      case FMT_D:
	return "D";
      case FMT_G:
	return "G";
      case FMT_E:
	return "E";
      case FMT_EN:
	return "EN";
      case FMT_ES:
	return "ES";
      default:
        return "";
    }
}

/* Check a format statement.  The format string, either from a FORMAT
   statement or a constant in an I/O statement has already been parsed
   by itself, and we are checking it for validity.  The dual origin
   means that the warning message is a little less than great.  */

static gfc_try
check_format (bool is_input)
{
  const char *posint_required	  = _("Positive width required");
  const char *nonneg_required	  = _("Nonnegative width required");
  const char *unexpected_element  = _("Unexpected element '%c' in format string"
				      " at %L");
  const char *unexpected_end	  = _("Unexpected end of format string");
  const char *zero_width	  = _("Zero width in format descriptor");

  const char *error;
  format_token t, u;
  int level;
  int repeat;
  gfc_try rv;

  use_last_char = 0;
  saved_token = FMT_NONE;
  level = 0;
  repeat = 0;
  rv = SUCCESS;
  format_string_pos = 0;

  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
  if (t != FMT_LPAREN)
    {
      error = _("Missing leading left parenthesis");
      goto syntax;
    }

  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
  if (t == FMT_RPAREN)
    goto finished;		/* Empty format is legal */
  saved_token = t;

format_item:
  /* In this state, the next thing has to be a format item.  */
  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
format_item_1:
  switch (t)
    {
    case FMT_STAR:
      repeat = -1;
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t == FMT_LPAREN)
	{
	  level++;
	  goto format_item;
	}
      error = _("Left parenthesis required after '*'");
      goto syntax;

    case FMT_POSINT:
      repeat = value;
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t == FMT_LPAREN)
	{
	  level++;
	  goto format_item;
	}

      if (t == FMT_SLASH)
	goto optional_comma;

      goto data_desc;

    case FMT_LPAREN:
      level++;
      goto format_item;

    case FMT_SIGNED_INT:
    case FMT_ZERO:
      /* Signed integer can only precede a P format.  */
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_P)
	{
	  error = _("Expected P edit descriptor");
	  goto syntax;
	}

      goto data_desc;

    case FMT_P:
      /* P requires a prior number.  */
      error = _("P descriptor requires leading scale factor");
      goto syntax;

    case FMT_X:
      /* X requires a prior number if we're being pedantic.  */
      if (mode != MODE_FORMAT)
	format_locus.nextc += format_string_pos;
      if (gfc_notify_std (GFC_STD_GNU, "Extension: X descriptor "
			  "requires leading space count at %L", &format_locus)
	  == FAILURE)
	return FAILURE;
      goto between_desc;

    case FMT_SIGN:
    case FMT_BLANK:
    case FMT_DP:
    case FMT_DC:
    case FMT_RC:
    case FMT_RD:
    case FMT_RN:
    case FMT_RP:
    case FMT_RU:
    case FMT_RZ:
      goto between_desc;

    case FMT_CHAR:
      goto extension_optional_comma;

    case FMT_COLON:
    case FMT_SLASH:
      goto optional_comma;

    case FMT_DOLLAR:
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;

      if (gfc_notify_std (GFC_STD_GNU, "Extension: $ descriptor at %L",
	  &format_locus) == FAILURE)
	return FAILURE;
      if (t != FMT_RPAREN || level > 0)
	{
	  gfc_warning ("$ should be the last specifier in format at %L",
		       &format_locus);
	  goto optional_comma_1;
	}

      goto finished;

    case FMT_T:
    case FMT_TL:
    case FMT_TR:
    case FMT_IBOZ:
    case FMT_F:
    case FMT_E:
    case FMT_EN:
    case FMT_ES:
    case FMT_G:
    case FMT_L:
    case FMT_A:
    case FMT_D:
    case FMT_H:
      goto data_desc;

    case FMT_END:
      error = unexpected_end;
      goto syntax;

    default:
      error = unexpected_element;
      goto syntax;
    }

data_desc:
  /* In this state, t must currently be a data descriptor.
     Deal with things that can/must follow the descriptor.  */
  switch (t)
    {
    case FMT_SIGN:
    case FMT_BLANK:
    case FMT_DP:
    case FMT_DC:
    case FMT_X:
      break;

    case FMT_P:
      /* No comma after P allowed only for F, E, EN, ES, D, or G.
	 10.1.1 (1).  */
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (!(gfc_option.allow_std & GFC_STD_F2003) && t != FMT_COMMA
	  && t != FMT_F && t != FMT_E && t != FMT_EN && t != FMT_ES
	  && t != FMT_D && t != FMT_G && t != FMT_RPAREN && t != FMT_SLASH)
	{
	  error = _("Comma required after P descriptor");
	  goto syntax;
	}
      if (t != FMT_COMMA)
	{
	  if (t == FMT_POSINT)
	    {
	      t = format_lex ();
	      if (t == FMT_ERROR)
		goto fail;
	    }
          if (t != FMT_F && t != FMT_E && t != FMT_EN && t != FMT_ES && t != FMT_D
	      && t != FMT_G && t != FMT_RPAREN && t != FMT_SLASH)
	    {
	      error = _("Comma required after P descriptor");
	      goto syntax;
	    }
	}

      saved_token = t;
      goto optional_comma;

    case FMT_T:
    case FMT_TL:
    case FMT_TR:
      t = format_lex ();
      if (t != FMT_POSINT)
	{
	  error = _("Positive width required with T descriptor");
	  goto syntax;
	}
      break;

    case FMT_L:
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t == FMT_POSINT)
	break;

      switch (gfc_notification_std (GFC_STD_GNU))
	{
	  case WARNING:
	    if (mode != MODE_FORMAT)
	      format_locus.nextc += format_string_pos;
	    gfc_warning ("Extension: Missing positive width after L "
			 "descriptor at %L", &format_locus);
	    saved_token = t;
	    break;

	  case ERROR:
	    error = posint_required;
	    goto syntax;

	  case SILENT:
	    saved_token = t;
	    break;

	  default:
	    gcc_unreachable ();
	}
      break;

    case FMT_A:
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t == FMT_ZERO)
	{
	  error = zero_width;
	  goto syntax;
	}
      if (t != FMT_POSINT)
	saved_token = t;
      break;

    case FMT_D:
    case FMT_E:
    case FMT_G:
    case FMT_EN:
    case FMT_ES:
      u = format_lex ();
      if (t == FMT_G && u == FMT_ZERO)
	{
	  if (is_input)
	    {
	      error = zero_width;
	      goto syntax;
	    }
	  if (gfc_notify_std (GFC_STD_F2008, "Fortran 2008: 'G0' in "
			      "format at %L", &format_locus) == FAILURE)
	    return FAILURE;
	  u = format_lex ();
	  if (u != FMT_PERIOD)
	    {
	      saved_token = u;
	      break;
	    }
	  u = format_lex ();
	  if (u != FMT_POSINT)
	    {
	      error = posint_required;
	      goto syntax;
	    }
	  u = format_lex ();
	  if (u == FMT_E)
	    {
	      error = _("E specifier not allowed with g0 descriptor");
	      goto syntax;
	    }
	  saved_token = u;
	  break;
	}

      if (u != FMT_POSINT)
	{
	  format_locus.nextc += format_string_pos;
	  gfc_error ("Positive width required in format "
			 "specifier %s at %L", token_to_string (t),
			 &format_locus);
	  saved_token = u;
	  goto fail;
	}

      u = format_lex ();
      if (u == FMT_ERROR)
	goto fail;
      if (u != FMT_PERIOD)
	{
	  /* Warn if -std=legacy, otherwise error.  */
	  format_locus.nextc += format_string_pos;
	  if (gfc_option.warn_std != 0)
	    {
	      gfc_error ("Period required in format "
			     "specifier %s at %L", token_to_string (t),
			     &format_locus);
	      saved_token = u;
              goto fail;
	    }
	  else
	    gfc_warning ("Period required in format "
			 "specifier %s at %L", token_to_string (t),
			  &format_locus);
	  /* If we go to finished, we need to unwind this
	     before the next round.  */
	  format_locus.nextc -= format_string_pos;
	  saved_token = u;
	  break;
	}

      u = format_lex ();
      if (u == FMT_ERROR)
	goto fail;
      if (u != FMT_ZERO && u != FMT_POSINT)
	{
	  error = nonneg_required;
	  goto syntax;
	}

      if (t == FMT_D)
	break;

      /* Look for optional exponent.  */
      u = format_lex ();
      if (u == FMT_ERROR)
	goto fail;
      if (u != FMT_E)
	{
	  saved_token = u;
	}
      else
	{
	  u = format_lex ();
	  if (u == FMT_ERROR)
	    goto fail;
	  if (u != FMT_POSINT)
	    {
	      error = _("Positive exponent width required");
	      goto syntax;
	    }
	}

      break;

    case FMT_F:
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_ZERO && t != FMT_POSINT)
	{
	  error = nonneg_required;
	  goto syntax;
	}
      else if (is_input && t == FMT_ZERO)
	{
	  error = posint_required;
	  goto syntax;
	}

      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_PERIOD)
	{
	  /* Warn if -std=legacy, otherwise error.  */
	  if (gfc_option.warn_std != 0)
	    {
	      error = _("Period required in format specifier");
	      goto syntax;
	    }
	  if (mode != MODE_FORMAT)
	    format_locus.nextc += format_string_pos;
	  gfc_warning ("Period required in format specifier at %L",
		       &format_locus);
	  saved_token = t;
	  break;
	}

      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_ZERO && t != FMT_POSINT)
	{
	  error = nonneg_required;
	  goto syntax;
	}

      break;

    case FMT_H:
      if (!(gfc_option.allow_std & GFC_STD_GNU) && !inhibit_warnings)
	{
	  if (mode != MODE_FORMAT)
	    format_locus.nextc += format_string_pos;
	  gfc_warning ("The H format specifier at %L is"
		       " a Fortran 95 deleted feature", &format_locus);
	}
      if (mode == MODE_STRING)
	{
	  format_string += value;
	  format_length -= value;
          format_string_pos += repeat;
	}
      else
	{
	  while (repeat >0)
	   {
	     next_char (INSTRING_WARN);
	     repeat -- ;
	   }
	}
     break;

    case FMT_IBOZ:
      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_ZERO && t != FMT_POSINT)
	{
	  error = nonneg_required;
	  goto syntax;
	}
      else if (is_input && t == FMT_ZERO)
	{
	  error = posint_required;
	  goto syntax;
	}

      t = format_lex ();
      if (t == FMT_ERROR)
	goto fail;
      if (t != FMT_PERIOD)
	{
	  saved_token = t;
	}
      else
	{
	  t = format_lex ();
	  if (t == FMT_ERROR)
	    goto fail;
	  if (t != FMT_ZERO && t != FMT_POSINT)
	    {
	      error = nonneg_required;
	      goto syntax;
	    }
	}

      break;

    default:
      error = unexpected_element;
      goto syntax;
    }

between_desc:
  /* Between a descriptor and what comes next.  */
  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
  switch (t)
    {

    case FMT_COMMA:
      goto format_item;

    case FMT_RPAREN:
      level--;
      if (level < 0)
	goto finished;
      goto between_desc;

    case FMT_COLON:
    case FMT_SLASH:
      goto optional_comma;

    case FMT_END:
      error = unexpected_end;
      goto syntax;

    default:
      if (mode != MODE_FORMAT)
	format_locus.nextc += format_string_pos - 1;
      if (gfc_notify_std (GFC_STD_GNU, "Extension: Missing comma at %L",
	  &format_locus) == FAILURE)
	return FAILURE;
      /* If we do not actually return a failure, we need to unwind this
         before the next round.  */
      if (mode != MODE_FORMAT)
	format_locus.nextc -= format_string_pos;
      goto format_item_1;
    }

optional_comma:
  /* Optional comma is a weird between state where we've just finished
     reading a colon, slash, dollar or P descriptor.  */
  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
optional_comma_1:
  switch (t)
    {
    case FMT_COMMA:
      break;

    case FMT_RPAREN:
      level--;
      if (level < 0)
	goto finished;
      goto between_desc;

    default:
      /* Assume that we have another format item.  */
      saved_token = t;
      break;
    }

  goto format_item;

extension_optional_comma:
  /* As a GNU extension, permit a missing comma after a string literal.  */
  t = format_lex ();
  if (t == FMT_ERROR)
    goto fail;
  switch (t)
    {
    case FMT_COMMA:
      break;

    case FMT_RPAREN:
      level--;
      if (level < 0)
	goto finished;
      goto between_desc;

    case FMT_COLON:
    case FMT_SLASH:
      goto optional_comma;

    case FMT_END:
      error = unexpected_end;
      goto syntax;

    default:
      if (mode != MODE_FORMAT)
	format_locus.nextc += format_string_pos;
      if (gfc_notify_std (GFC_STD_GNU, "Extension: Missing comma at %L",
	  &format_locus) == FAILURE)
	return FAILURE;
      /* If we do not actually return a failure, we need to unwind this
         before the next round.  */
      if (mode != MODE_FORMAT)
	format_locus.nextc -= format_string_pos;
      saved_token = t;
      break;
    }

  goto format_item;
  
syntax:
  if (mode != MODE_FORMAT)
    format_locus.nextc += format_string_pos;
  if (error == unexpected_element)
    gfc_error (error, error_element, &format_locus);
  else
    gfc_error ("%s in format string at %L", error, &format_locus);
fail:
  rv = FAILURE;

finished:
  return rv;
}


/* Given an expression node that is a constant string, see if it looks
   like a format string.  */

static gfc_try
check_format_string (gfc_expr *e, bool is_input)
{
  gfc_try rv;
  int i;
  if (!e || e->ts.type != BT_CHARACTER || e->expr_type != EXPR_CONSTANT)
    return SUCCESS;

  mode = MODE_STRING;
  format_string = e->value.character.string;

  /* More elaborate measures are needed to show where a problem is within a
     format string that has been calculated, but that's probably not worth the
     effort.  */
  format_locus = e->where;
  rv = check_format (is_input);
  /* check for extraneous characters at the end of an otherwise valid format
     string, like '(A10,I3)F5'
     start at the end and move back to the last character processed,
     spaces are OK */
  if (rv == SUCCESS && e->value.character.length > format_string_pos)
    for (i=e->value.character.length-1;i>format_string_pos-1;i--)
      if (e->value.character.string[i] != ' ')
        {
          format_locus.nextc += format_length + 1; 
          gfc_warning ("Extraneous characters in format at %L", &format_locus); 
          break;
        }
  return rv;
}


/************ Fortran 95 I/O statement matchers *************/

/* Match a FORMAT statement.  This amounts to actually parsing the
   format descriptors in order to correctly locate the end of the
   format string.  */

match
gfc_match_format (void)
{
  gfc_expr *e;
  locus start;

  if (gfc_current_ns->proc_name
      && gfc_current_ns->proc_name->attr.flavor == FL_MODULE)
    {
      gfc_error ("Format statement in module main block at %C");
      return MATCH_ERROR;
    }

  if (gfc_statement_label == NULL)
    {
      gfc_error ("Missing format label at %C");
      return MATCH_ERROR;
    }
  gfc_gobble_whitespace ();

  mode = MODE_FORMAT;
  format_length = 0;

  start = gfc_current_locus;

  if (check_format (false) == FAILURE)
    return MATCH_ERROR;

  if (gfc_match_eos () != MATCH_YES)
    {
      gfc_syntax_error (ST_FORMAT);
      return MATCH_ERROR;
    }

  /* The label doesn't get created until after the statement is done
     being matched, so we have to leave the string for later.  */

  gfc_current_locus = start;	/* Back to the beginning */

  new_st.loc = start;
  new_st.op = EXEC_NOP;

  e = gfc_get_character_expr (gfc_default_character_kind, &start,
			      NULL, format_length);
  format_string = e->value.character.string;
  gfc_statement_label->format = e;

  mode = MODE_COPY;
  check_format (false);		/* Guaranteed to succeed */
  gfc_match_eos ();		/* Guaranteed to succeed */

  return MATCH_YES;
}


/* Match an expression I/O tag of some sort.  */

static match
match_etag (const io_tag *tag, gfc_expr **v)
{
  gfc_expr *result;
  match m;

  m = gfc_match (tag->spec);
  if (m != MATCH_YES)
    return m;

  m = gfc_match (tag->value, &result);
  if (m != MATCH_YES)
    {
      gfc_error ("Invalid value for %s specification at %C", tag->name);
      return MATCH_ERROR;
    }

  if (*v != NULL)
    {
      gfc_error ("Duplicate %s specification at %C", tag->name);
      gfc_free_expr (result);
      return MATCH_ERROR;
    }

  *v = result;
  return MATCH_YES;
}


/* Match a variable I/O tag of some sort.  */

static match
match_vtag (const io_tag *tag, gfc_expr **v)
{
  gfc_expr *result;
  match m;

  m = gfc_match (tag->spec);
  if (m != MATCH_YES)
    return m;

  m = gfc_match (tag->value, &result);
  if (m != MATCH_YES)
    {
      gfc_error ("Invalid value for %s specification at %C", tag->name);
      return MATCH_ERROR;
    }

  if (*v != NULL)
    {
      gfc_error ("Duplicate %s specification at %C", tag->name);
      gfc_free_expr (result);
      return MATCH_ERROR;
    }

  if (result->symtree->n.sym->attr.intent == INTENT_IN)
    {
      gfc_error ("Variable %s cannot be INTENT(IN) at %C", tag->name);
      gfc_free_expr (result);
      return MATCH_ERROR;
    }

  if (gfc_pure (NULL) && gfc_impure_variable (result->symtree->n.sym))
    {
      gfc_error ("Variable %s cannot be assigned in PURE procedure at %C",
		 tag->name);
      gfc_free_expr (result);
      return MATCH_ERROR;
    }

  if (gfc_implicit_pure (NULL) && gfc_impure_variable (result->symtree->n.sym))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  *v = result;
  return MATCH_YES;
}


/* Match I/O tags that cause variables to become redefined.  */

static match
match_out_tag (const io_tag *tag, gfc_expr **result)
{
  match m;

  m = match_vtag (tag, result);
  if (m == MATCH_YES)
    gfc_check_do_variable ((*result)->symtree);

  return m;
}


/* Match a label I/O tag.  */

static match
match_ltag (const io_tag *tag, gfc_st_label ** label)
{
  match m;
  gfc_st_label *old;

  old = *label;
  m = gfc_match (tag->spec);
  if (m != MATCH_YES)
    return m;

  m = gfc_match (tag->value, label);
  if (m != MATCH_YES)
    {
      gfc_error ("Invalid value for %s specification at %C", tag->name);
      return MATCH_ERROR;
    }

  if (old)
    {
      gfc_error ("Duplicate %s label specification at %C", tag->name);
      return MATCH_ERROR;
    }

  if (gfc_reference_st_label (*label, ST_LABEL_TARGET) == FAILURE)
    return MATCH_ERROR;

  return m;
}


/* Resolution of the FORMAT tag, to be called from resolve_tag.  */

static gfc_try
resolve_tag_format (const gfc_expr *e)
{
  if (e->expr_type == EXPR_CONSTANT
      && (e->ts.type != BT_CHARACTER
	  || e->ts.kind != gfc_default_character_kind))
    {
      gfc_error ("Constant expression in FORMAT tag at %L must be "
		 "of type default CHARACTER", &e->where);
      return FAILURE;
    }

  /* If e's rank is zero and e is not an element of an array, it should be
     of integer or character type.  The integer variable should be
     ASSIGNED.  */
  if (e->rank == 0
      && (e->expr_type != EXPR_VARIABLE
	  || e->symtree == NULL
	  || e->symtree->n.sym->as == NULL
	  || e->symtree->n.sym->as->rank == 0))
    {
      if (e->ts.type != BT_CHARACTER && e->ts.type != BT_INTEGER)
	{
	  gfc_error ("FORMAT tag at %L must be of type CHARACTER or INTEGER",
		     &e->where);
	  return FAILURE;
	}
      else if (e->ts.type == BT_INTEGER && e->expr_type == EXPR_VARIABLE)
	{
	  if (gfc_notify_std (GFC_STD_F95_DEL, "Deleted feature: ASSIGNED "
			      "variable in FORMAT tag at %L", &e->where)
	      == FAILURE)
	    return FAILURE;
	  if (e->symtree->n.sym->attr.assign != 1)
	    {
	      gfc_error ("Variable '%s' at %L has not been assigned a "
			 "format label", e->symtree->n.sym->name, &e->where);
	      return FAILURE;
	    }
	}
      else if (e->ts.type == BT_INTEGER)
	{
	  gfc_error ("Scalar '%s' in FORMAT tag at %L is not an ASSIGNED "
		     "variable", gfc_basic_typename (e->ts.type), &e->where);
	  return FAILURE;
	}

      return SUCCESS;
    }

  /* If rank is nonzero and type is not character, we allow it under GFC_STD_LEGACY.
     It may be assigned an Hollerith constant.  */
  if (e->ts.type != BT_CHARACTER)
    {
      if (gfc_notify_std (GFC_STD_LEGACY, "Extension: Non-character "
			  "in FORMAT tag at %L", &e->where) == FAILURE)
	return FAILURE;

      if (e->rank == 0 && e->symtree->n.sym->as->type == AS_ASSUMED_SHAPE)
	{
	  gfc_error ("Non-character assumed shape array element in FORMAT"
		     " tag at %L", &e->where);
	  return FAILURE;
	}

      if (e->rank == 0 && e->symtree->n.sym->as->type == AS_ASSUMED_SIZE)
	{
	  gfc_error ("Non-character assumed size array element in FORMAT"
		     " tag at %L", &e->where);
	  return FAILURE;
	}

      if (e->rank == 0 && e->symtree->n.sym->attr.pointer)
	{
	  gfc_error ("Non-character pointer array element in FORMAT tag at %L",
		     &e->where);
	  return FAILURE;
	}
    }

  return SUCCESS;
}


/* Do expression resolution and type-checking on an expression tag.  */

static gfc_try
resolve_tag (const io_tag *tag, gfc_expr *e)
{
  if (e == NULL)
    return SUCCESS;

  if (gfc_resolve_expr (e) == FAILURE)
    return FAILURE;

  if (tag == &tag_format)
    return resolve_tag_format (e);

  if (e->ts.type != tag->type)
    {
      gfc_error ("%s tag at %L must be of type %s", tag->name,
		 &e->where, gfc_basic_typename (tag->type));
      return FAILURE;
    }

  if (e->rank != 0)
    {
      gfc_error ("%s tag at %L must be scalar", tag->name, &e->where);
      return FAILURE;
    }

  if (tag == &tag_iomsg)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: IOMSG tag at %L",
			  &e->where) == FAILURE)
	return FAILURE;
    }

  if ((tag == &tag_iostat || tag == &tag_size || tag == &tag_iolength)
      && e->ts.kind != gfc_default_integer_kind)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 95 requires default "
			  "INTEGER in %s tag at %L", tag->name, &e->where)
	  == FAILURE)
	return FAILURE;
    }

  if (tag == &tag_exist && e->ts.kind != gfc_default_logical_kind)
    {
      if (gfc_notify_std (GFC_STD_F2008, "Fortran 2008: Nondefault LOGICAL "
			  "in %s tag at %L", tag->name, &e->where)
	  == FAILURE)
	return FAILURE;
    }

  if (tag == &tag_newunit)
    {
      if (gfc_notify_std (GFC_STD_F2008, "Fortran 2008: NEWUNIT specifier"
			  " at %L", &e->where) == FAILURE)
	return FAILURE;
    }

  /* NEWUNIT, IOSTAT, SIZE and IOMSG are variable definition contexts.  */
  if (tag == &tag_newunit || tag == &tag_iostat
      || tag == &tag_size || tag == &tag_iomsg)
    {
      char context[64];

      sprintf (context, _("%s tag"), tag->name);
      if (gfc_check_vardef_context (e, false, context) == FAILURE)
	return FAILURE;
    }
  
  if (tag == &tag_convert)
    {
      if (gfc_notify_std (GFC_STD_GNU, "Extension: CONVERT tag at %L",
			  &e->where) == FAILURE)
	return FAILURE;
    }

  return SUCCESS;
}


/* Match a single tag of an OPEN statement.  */

static match
match_open_element (gfc_open *open)
{
  match m;

  m = match_etag (&tag_e_async, &open->asynchronous);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_unit, &open->unit);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iomsg, &open->iomsg);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iostat, &open->iostat);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_file, &open->file);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_status, &open->status);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_access, &open->access);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_form, &open->form);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_recl, &open->recl);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_blank, &open->blank);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_position, &open->position);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_action, &open->action);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_delim, &open->delim);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_pad, &open->pad);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_decimal, &open->decimal);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_encoding, &open->encoding);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_round, &open->round);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_sign, &open->sign);
  if (m != MATCH_NO)
    return m;
  m = match_ltag (&tag_err, &open->err);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_convert, &open->convert);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_newunit, &open->newunit);
  if (m != MATCH_NO)
    return m;

  return MATCH_NO;
}


/* Free the gfc_open structure and all the expressions it contains.  */

void
gfc_free_open (gfc_open *open)
{
  if (open == NULL)
    return;

  gfc_free_expr (open->unit);
  gfc_free_expr (open->iomsg);
  gfc_free_expr (open->iostat);
  gfc_free_expr (open->file);
  gfc_free_expr (open->status);
  gfc_free_expr (open->access);
  gfc_free_expr (open->form);
  gfc_free_expr (open->recl);
  gfc_free_expr (open->blank);
  gfc_free_expr (open->position);
  gfc_free_expr (open->action);
  gfc_free_expr (open->delim);
  gfc_free_expr (open->pad);
  gfc_free_expr (open->decimal);
  gfc_free_expr (open->encoding);
  gfc_free_expr (open->round);
  gfc_free_expr (open->sign);
  gfc_free_expr (open->convert);
  gfc_free_expr (open->asynchronous);
  gfc_free_expr (open->newunit);
  gfc_free (open);
}


/* Resolve everything in a gfc_open structure.  */

gfc_try
gfc_resolve_open (gfc_open *open)
{

  RESOLVE_TAG (&tag_unit, open->unit);
  RESOLVE_TAG (&tag_iomsg, open->iomsg);
  RESOLVE_TAG (&tag_iostat, open->iostat);
  RESOLVE_TAG (&tag_file, open->file);
  RESOLVE_TAG (&tag_status, open->status);
  RESOLVE_TAG (&tag_e_access, open->access);
  RESOLVE_TAG (&tag_e_form, open->form);
  RESOLVE_TAG (&tag_e_recl, open->recl);
  RESOLVE_TAG (&tag_e_blank, open->blank);
  RESOLVE_TAG (&tag_e_position, open->position);
  RESOLVE_TAG (&tag_e_action, open->action);
  RESOLVE_TAG (&tag_e_delim, open->delim);
  RESOLVE_TAG (&tag_e_pad, open->pad);
  RESOLVE_TAG (&tag_e_decimal, open->decimal);
  RESOLVE_TAG (&tag_e_encoding, open->encoding);
  RESOLVE_TAG (&tag_e_async, open->asynchronous);
  RESOLVE_TAG (&tag_e_round, open->round);
  RESOLVE_TAG (&tag_e_sign, open->sign);
  RESOLVE_TAG (&tag_convert, open->convert);
  RESOLVE_TAG (&tag_newunit, open->newunit);

  if (gfc_reference_st_label (open->err, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;

  return SUCCESS;
}


/* Check if a given value for a SPECIFIER is either in the list of values
   allowed in F95 or F2003, issuing an error message and returning a zero
   value if it is not allowed.  */

static int
compare_to_allowed_values (const char *specifier, const char *allowed[],
			   const char *allowed_f2003[], 
			   const char *allowed_gnu[], gfc_char_t *value,
			   const char *statement, bool warn)
{
  int i;
  unsigned int len;

  len = gfc_wide_strlen (value);
  if (len > 0)
  {
    for (len--; len > 0; len--)
      if (value[len] != ' ')
	break;
    len++;
  }

  for (i = 0; allowed[i]; i++)
    if (len == strlen (allowed[i])
	&& gfc_wide_strncasecmp (value, allowed[i], strlen (allowed[i])) == 0)
      return 1;

  for (i = 0; allowed_f2003 && allowed_f2003[i]; i++)
    if (len == strlen (allowed_f2003[i])
	&& gfc_wide_strncasecmp (value, allowed_f2003[i],
				 strlen (allowed_f2003[i])) == 0)
      {
	notification n = gfc_notification_std (GFC_STD_F2003);

	if (n == WARNING || (warn && n == ERROR))
	  {
	    gfc_warning ("Fortran 2003: %s specifier in %s statement at %C "
			 "has value '%s'", specifier, statement,
			 allowed_f2003[i]);
	    return 1;
	  }
	else
	  if (n == ERROR)
	    {
	      gfc_notify_std (GFC_STD_F2003, "Fortran 2003: %s specifier in "
			      "%s statement at %C has value '%s'", specifier,
			      statement, allowed_f2003[i]);
	      return 0;
	    }

	/* n == SILENT */
	return 1;
      }

  for (i = 0; allowed_gnu && allowed_gnu[i]; i++)
    if (len == strlen (allowed_gnu[i])
	&& gfc_wide_strncasecmp (value, allowed_gnu[i],
				 strlen (allowed_gnu[i])) == 0)
      {
	notification n = gfc_notification_std (GFC_STD_GNU);

	if (n == WARNING || (warn && n == ERROR))
	  {
	    gfc_warning ("Extension: %s specifier in %s statement at %C "
			 "has value '%s'", specifier, statement,
			 allowed_gnu[i]);
	    return 1;
	  }
	else
	  if (n == ERROR)
	    {
	      gfc_notify_std (GFC_STD_GNU, "Extension: %s specifier in "
			      "%s statement at %C has value '%s'", specifier,
			      statement, allowed_gnu[i]);
	      return 0;
	    }

	/* n == SILENT */
	return 1;
      }

  if (warn)
    {
      char *s = gfc_widechar_to_char (value, -1);
      gfc_warning ("%s specifier in %s statement at %C has invalid value '%s'",
		   specifier, statement, s);
      gfc_free (s);
      return 1;
    }
  else
    {
      char *s = gfc_widechar_to_char (value, -1);
      gfc_error ("%s specifier in %s statement at %C has invalid value '%s'",
		 specifier, statement, s);
      gfc_free (s);
      return 0;
    }
}


/* Match an OPEN statement.  */

match
gfc_match_open (void)
{
  gfc_open *open;
  match m;
  bool warn;

  m = gfc_match_char ('(');
  if (m == MATCH_NO)
    return m;

  open = XCNEW (gfc_open);

  m = match_open_element (open);

  if (m == MATCH_ERROR)
    goto cleanup;
  if (m == MATCH_NO)
    {
      m = gfc_match_expr (&open->unit);
      if (m == MATCH_ERROR)
	goto cleanup;
    }

  for (;;)
    {
      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;

      m = match_open_element (open);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  if (gfc_match_eos () == MATCH_NO)
    goto syntax;

  if (gfc_pure (NULL))
    {
      gfc_error ("OPEN statement not allowed in PURE procedure at %C");
      goto cleanup;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  warn = (open->err || open->iostat) ? true : false;

  /* Checks on NEWUNIT specifier.  */
  if (open->newunit)
    {
      if (open->unit)
	{
	  gfc_error ("UNIT specifier not allowed with NEWUNIT at %C");
	  goto cleanup;
	}

      if (!(open->file || (open->status
          && gfc_wide_strncasecmp (open->status->value.character.string,
				   "scratch", 7) == 0)))
	{
	  gfc_error ("NEWUNIT specifier must have FILE= "
		     "or STATUS='scratch' at %C");
	  goto cleanup;
	}
    }
  else if (!open->unit)
    {
      gfc_error ("OPEN statement at %C must have UNIT or NEWUNIT specified");
      goto cleanup;
    }

  /* Checks on the ACCESS specifier.  */
  if (open->access && open->access->expr_type == EXPR_CONSTANT)
    {
      static const char *access_f95[] = { "SEQUENTIAL", "DIRECT", NULL };
      static const char *access_f2003[] = { "STREAM", NULL };
      static const char *access_gnu[] = { "APPEND", NULL };

      if (!compare_to_allowed_values ("ACCESS", access_f95, access_f2003,
				      access_gnu,
				      open->access->value.character.string,
				      "OPEN", warn))
	goto cleanup;
    }

  /* Checks on the ACTION specifier.  */
  if (open->action && open->action->expr_type == EXPR_CONSTANT)
    {
      static const char *action[] = { "READ", "WRITE", "READWRITE", NULL };

      if (!compare_to_allowed_values ("ACTION", action, NULL, NULL,
				      open->action->value.character.string,
				      "OPEN", warn))
	goto cleanup;
    }

  /* Checks on the ASYNCHRONOUS specifier.  */
  if (open->asynchronous)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: ASYNCHRONOUS= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;

      if (open->asynchronous->expr_type == EXPR_CONSTANT)
	{
	  static const char * asynchronous[] = { "YES", "NO", NULL };

	  if (!compare_to_allowed_values ("ASYNCHRONOUS", asynchronous,
			NULL, NULL, open->asynchronous->value.character.string,
			"OPEN", warn))
	    goto cleanup;
	}
    }

  /* Checks on the BLANK specifier.  */
  if (open->blank)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: BLANK= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;

      if (open->blank->expr_type == EXPR_CONSTANT)
	{
	  static const char *blank[] = { "ZERO", "NULL", NULL };

	  if (!compare_to_allowed_values ("BLANK", blank, NULL, NULL,
					  open->blank->value.character.string,
					  "OPEN", warn))
	    goto cleanup;
	}
    }

  /* Checks on the DECIMAL specifier.  */
  if (open->decimal)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DECIMAL= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;

      if (open->decimal->expr_type == EXPR_CONSTANT)
	{
	  static const char * decimal[] = { "COMMA", "POINT", NULL };

	  if (!compare_to_allowed_values ("DECIMAL", decimal, NULL, NULL,
					  open->decimal->value.character.string,
					  "OPEN", warn))
	    goto cleanup;
	}
    }

  /* Checks on the DELIM specifier.  */
  if (open->delim)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DELIM= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;

      if (open->delim->expr_type == EXPR_CONSTANT)
	{
	  static const char *delim[] = { "APOSTROPHE", "QUOTE", "NONE", NULL };

	  if (!compare_to_allowed_values ("DELIM", delim, NULL, NULL,
					  open->delim->value.character.string,
					  "OPEN", warn))
	  goto cleanup;
	}
    }

  /* Checks on the ENCODING specifier.  */
  if (open->encoding)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: ENCODING= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;
    
      if (open->encoding->expr_type == EXPR_CONSTANT)
	{
	  static const char * encoding[] = { "DEFAULT", "UTF-8", NULL };

	  if (!compare_to_allowed_values ("ENCODING", encoding, NULL, NULL,
					  open->encoding->value.character.string,
					  "OPEN", warn))
	  goto cleanup;
	}
    }

  /* Checks on the FORM specifier.  */
  if (open->form && open->form->expr_type == EXPR_CONSTANT)
    {
      static const char *form[] = { "FORMATTED", "UNFORMATTED", NULL };

      if (!compare_to_allowed_values ("FORM", form, NULL, NULL,
				      open->form->value.character.string,
				      "OPEN", warn))
	goto cleanup;
    }

  /* Checks on the PAD specifier.  */
  if (open->pad && open->pad->expr_type == EXPR_CONSTANT)
    {
      static const char *pad[] = { "YES", "NO", NULL };

      if (!compare_to_allowed_values ("PAD", pad, NULL, NULL,
				      open->pad->value.character.string,
				      "OPEN", warn))
	goto cleanup;
    }

  /* Checks on the POSITION specifier.  */
  if (open->position && open->position->expr_type == EXPR_CONSTANT)
    {
      static const char *position[] = { "ASIS", "REWIND", "APPEND", NULL };

      if (!compare_to_allowed_values ("POSITION", position, NULL, NULL,
				      open->position->value.character.string,
				      "OPEN", warn))
	goto cleanup;
    }

  /* Checks on the ROUND specifier.  */
  if (open->round)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran F2003: ROUND= at %C "
	  "not allowed in Fortran 95") == FAILURE)
      goto cleanup;

      if (open->round->expr_type == EXPR_CONSTANT)
	{
	  static const char * round[] = { "UP", "DOWN", "ZERO", "NEAREST",
					  "COMPATIBLE", "PROCESSOR_DEFINED",
					   NULL };

	  if (!compare_to_allowed_values ("ROUND", round, NULL, NULL,
					  open->round->value.character.string,
					  "OPEN", warn))
	  goto cleanup;
	}
    }

  /* Checks on the SIGN specifier.  */
  if (open->sign) 
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: SIGN= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	goto cleanup;

      if (open->sign->expr_type == EXPR_CONSTANT)
	{
	  static const char * sign[] = { "PLUS", "SUPPRESS", "PROCESSOR_DEFINED",
					  NULL };

	  if (!compare_to_allowed_values ("SIGN", sign, NULL, NULL,
					  open->sign->value.character.string,
					  "OPEN", warn))
	  goto cleanup;
	}
    }

#define warn_or_error(...) \
{ \
  if (warn) \
    gfc_warning (__VA_ARGS__); \
  else \
    { \
      gfc_error (__VA_ARGS__); \
      goto cleanup; \
    } \
}

  /* Checks on the RECL specifier.  */
  if (open->recl && open->recl->expr_type == EXPR_CONSTANT
      && open->recl->ts.type == BT_INTEGER
      && mpz_sgn (open->recl->value.integer) != 1)
    {
      warn_or_error ("RECL in OPEN statement at %C must be positive");
    }

  /* Checks on the STATUS specifier.  */
  if (open->status && open->status->expr_type == EXPR_CONSTANT)
    {
      static const char *status[] = { "OLD", "NEW", "SCRATCH",
	"REPLACE", "UNKNOWN", NULL };

      if (!compare_to_allowed_values ("STATUS", status, NULL, NULL,
				      open->status->value.character.string,
				      "OPEN", warn))
	goto cleanup;

      /* F2003, 9.4.5: If the STATUS= specifier has the value NEW or REPLACE,
	 the FILE= specifier shall appear.  */
      if (open->file == NULL
	  && (gfc_wide_strncasecmp (open->status->value.character.string,
				    "replace", 7) == 0
	      || gfc_wide_strncasecmp (open->status->value.character.string,
				       "new", 3) == 0))
	{
	  char *s = gfc_widechar_to_char (open->status->value.character.string,
					  -1);
	  warn_or_error ("The STATUS specified in OPEN statement at %C is "
			 "'%s' and no FILE specifier is present", s);
	  gfc_free (s);
	}

      /* F2003, 9.4.5: If the STATUS= specifier has the value SCRATCH,
	 the FILE= specifier shall not appear.  */
      if (gfc_wide_strncasecmp (open->status->value.character.string,
				"scratch", 7) == 0 && open->file)
	{
	  warn_or_error ("The STATUS specified in OPEN statement at %C "
			 "cannot have the value SCRATCH if a FILE specifier "
			 "is present");
	}
    }

  /* Things that are not allowed for unformatted I/O.  */
  if (open->form && open->form->expr_type == EXPR_CONSTANT
      && (open->delim || open->decimal || open->encoding || open->round
	  || open->sign || open->pad || open->blank)
      && gfc_wide_strncasecmp (open->form->value.character.string,
			       "unformatted", 11) == 0)
    {
      const char *spec = (open->delim ? "DELIM "
				      : (open->pad ? "PAD " : open->blank
							    ? "BLANK " : ""));

      warn_or_error ("%s specifier at %C not allowed in OPEN statement for "
		     "unformatted I/O", spec);
    }

  if (open->recl && open->access && open->access->expr_type == EXPR_CONSTANT
      && gfc_wide_strncasecmp (open->access->value.character.string,
			       "stream", 6) == 0)
    {
      warn_or_error ("RECL specifier not allowed in OPEN statement at %C for "
		     "stream I/O");
    }

  if (open->position
      && open->access && open->access->expr_type == EXPR_CONSTANT
      && !(gfc_wide_strncasecmp (open->access->value.character.string,
				 "sequential", 10) == 0
	   || gfc_wide_strncasecmp (open->access->value.character.string,
				    "stream", 6) == 0
	   || gfc_wide_strncasecmp (open->access->value.character.string,
				    "append", 6) == 0))
    {
      warn_or_error ("POSITION specifier in OPEN statement at %C only allowed "
		     "for stream or sequential ACCESS");
    }

#undef warn_or_error

  new_st.op = EXEC_OPEN;
  new_st.ext.open = open;
  return MATCH_YES;

syntax:
  gfc_syntax_error (ST_OPEN);

cleanup:
  gfc_free_open (open);
  return MATCH_ERROR;
}


/* Free a gfc_close structure an all its expressions.  */

void
gfc_free_close (gfc_close *close)
{
  if (close == NULL)
    return;

  gfc_free_expr (close->unit);
  gfc_free_expr (close->iomsg);
  gfc_free_expr (close->iostat);
  gfc_free_expr (close->status);
  gfc_free (close);
}


/* Match elements of a CLOSE statement.  */

static match
match_close_element (gfc_close *close)
{
  match m;

  m = match_etag (&tag_unit, &close->unit);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_status, &close->status);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iomsg, &close->iomsg);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iostat, &close->iostat);
  if (m != MATCH_NO)
    return m;
  m = match_ltag (&tag_err, &close->err);
  if (m != MATCH_NO)
    return m;

  return MATCH_NO;
}


/* Match a CLOSE statement.  */

match
gfc_match_close (void)
{
  gfc_close *close;
  match m;
  bool warn;

  m = gfc_match_char ('(');
  if (m == MATCH_NO)
    return m;

  close = XCNEW (gfc_close);

  m = match_close_element (close);

  if (m == MATCH_ERROR)
    goto cleanup;
  if (m == MATCH_NO)
    {
      m = gfc_match_expr (&close->unit);
      if (m == MATCH_NO)
	goto syntax;
      if (m == MATCH_ERROR)
	goto cleanup;
    }

  for (;;)
    {
      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;

      m = match_close_element (close);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  if (gfc_match_eos () == MATCH_NO)
    goto syntax;

  if (gfc_pure (NULL))
    {
      gfc_error ("CLOSE statement not allowed in PURE procedure at %C");
      goto cleanup;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  warn = (close->iostat || close->err) ? true : false;

  /* Checks on the STATUS specifier.  */
  if (close->status && close->status->expr_type == EXPR_CONSTANT)
    {
      static const char *status[] = { "KEEP", "DELETE", NULL };

      if (!compare_to_allowed_values ("STATUS", status, NULL, NULL,
				      close->status->value.character.string,
				      "CLOSE", warn))
	goto cleanup;
    }

  new_st.op = EXEC_CLOSE;
  new_st.ext.close = close;
  return MATCH_YES;

syntax:
  gfc_syntax_error (ST_CLOSE);

cleanup:
  gfc_free_close (close);
  return MATCH_ERROR;
}


/* Resolve everything in a gfc_close structure.  */

gfc_try
gfc_resolve_close (gfc_close *close)
{
  RESOLVE_TAG (&tag_unit, close->unit);
  RESOLVE_TAG (&tag_iomsg, close->iomsg);
  RESOLVE_TAG (&tag_iostat, close->iostat);
  RESOLVE_TAG (&tag_status, close->status);

  if (gfc_reference_st_label (close->err, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;

  if (close->unit->expr_type == EXPR_CONSTANT
      && close->unit->ts.type == BT_INTEGER
      && mpz_sgn (close->unit->value.integer) < 0)
    {
      gfc_error ("UNIT number in CLOSE statement at %L must be non-negative",
		 &close->unit->where);
    }

  return SUCCESS;
}


/* Free a gfc_filepos structure.  */

void
gfc_free_filepos (gfc_filepos *fp)
{
  gfc_free_expr (fp->unit);
  gfc_free_expr (fp->iomsg);
  gfc_free_expr (fp->iostat);
  gfc_free (fp);
}


/* Match elements of a REWIND, BACKSPACE, ENDFILE, or FLUSH statement.  */

static match
match_file_element (gfc_filepos *fp)
{
  match m;

  m = match_etag (&tag_unit, &fp->unit);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iomsg, &fp->iomsg);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iostat, &fp->iostat);
  if (m != MATCH_NO)
    return m;
  m = match_ltag (&tag_err, &fp->err);
  if (m != MATCH_NO)
    return m;

  return MATCH_NO;
}


/* Match the second half of the file-positioning statements, REWIND,
   BACKSPACE, ENDFILE, or the FLUSH statement.  */

static match
match_filepos (gfc_statement st, gfc_exec_op op)
{
  gfc_filepos *fp;
  match m;

  fp = XCNEW (gfc_filepos);

  if (gfc_match_char ('(') == MATCH_NO)
    {
      m = gfc_match_expr (&fp->unit);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;

      goto done;
    }

  m = match_file_element (fp);
  if (m == MATCH_ERROR)
    goto done;
  if (m == MATCH_NO)
    {
      m = gfc_match_expr (&fp->unit);
      if (m == MATCH_ERROR)
	goto done;
      if (m == MATCH_NO)
	goto syntax;
    }

  for (;;)
    {
      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;

      m = match_file_element (fp);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

done:
  if (gfc_match_eos () != MATCH_YES)
    goto syntax;

  if (gfc_pure (NULL))
    {
      gfc_error ("%s statement not allowed in PURE procedure at %C",
		 gfc_ascii_statement (st));

      goto cleanup;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  new_st.op = op;
  new_st.ext.filepos = fp;
  return MATCH_YES;

syntax:
  gfc_syntax_error (st);

cleanup:
  gfc_free_filepos (fp);
  return MATCH_ERROR;
}


gfc_try
gfc_resolve_filepos (gfc_filepos *fp)
{
  RESOLVE_TAG (&tag_unit, fp->unit);
  RESOLVE_TAG (&tag_iostat, fp->iostat);
  RESOLVE_TAG (&tag_iomsg, fp->iomsg);
  if (gfc_reference_st_label (fp->err, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;

  if (fp->unit->expr_type == EXPR_CONSTANT
      && fp->unit->ts.type == BT_INTEGER
      && mpz_sgn (fp->unit->value.integer) < 0)
    {
      gfc_error ("UNIT number in statement at %L must be non-negative",
		 &fp->unit->where);
    }

  return SUCCESS;
}


/* Match the file positioning statements: ENDFILE, BACKSPACE, REWIND,
   and the FLUSH statement.  */

match
gfc_match_endfile (void)
{
  return match_filepos (ST_END_FILE, EXEC_ENDFILE);
}

match
gfc_match_backspace (void)
{
  return match_filepos (ST_BACKSPACE, EXEC_BACKSPACE);
}

match
gfc_match_rewind (void)
{
  return match_filepos (ST_REWIND, EXEC_REWIND);
}

match
gfc_match_flush (void)
{
  if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: FLUSH statement at %C")
      == FAILURE)
    return MATCH_ERROR;

  return match_filepos (ST_FLUSH, EXEC_FLUSH);
}

/******************** Data Transfer Statements *********************/

/* Return a default unit number.  */

static gfc_expr *
default_unit (io_kind k)
{
  int unit;

  if (k == M_READ)
    unit = 5;
  else
    unit = 6;

  return gfc_get_int_expr (gfc_default_integer_kind, NULL, unit);
}


/* Match a unit specification for a data transfer statement.  */

static match
match_dt_unit (io_kind k, gfc_dt *dt)
{
  gfc_expr *e;

  if (gfc_match_char ('*') == MATCH_YES)
    {
      if (dt->io_unit != NULL)
	goto conflict;

      dt->io_unit = default_unit (k);
      return MATCH_YES;
    }

  if (gfc_match_expr (&e) == MATCH_YES)
    {
      if (dt->io_unit != NULL)
	{
	  gfc_free_expr (e);
	  goto conflict;
	}

      dt->io_unit = e;
      return MATCH_YES;
    }

  return MATCH_NO;

conflict:
  gfc_error ("Duplicate UNIT specification at %C");
  return MATCH_ERROR;
}


/* Match a format specification.  */

static match
match_dt_format (gfc_dt *dt)
{
  locus where;
  gfc_expr *e;
  gfc_st_label *label;
  match m;

  where = gfc_current_locus;

  if (gfc_match_char ('*') == MATCH_YES)
    {
      if (dt->format_expr != NULL || dt->format_label != NULL)
	goto conflict;

      dt->format_label = &format_asterisk;
      return MATCH_YES;
    }

  if ((m = gfc_match_st_label (&label)) == MATCH_YES)
    {
      if (dt->format_expr != NULL || dt->format_label != NULL)
	{
	  gfc_free_st_label (label);
	  goto conflict;
	}

      if (gfc_reference_st_label (label, ST_LABEL_FORMAT) == FAILURE)
	return MATCH_ERROR;

      dt->format_label = label;
      return MATCH_YES;
    }
  else if (m == MATCH_ERROR)
    /* The label was zero or too large.  Emit the correct diagnosis.  */
    return MATCH_ERROR;

  if (gfc_match_expr (&e) == MATCH_YES)
    {
      if (dt->format_expr != NULL || dt->format_label != NULL)
	{
	  gfc_free_expr (e);
	  goto conflict;
	}
      dt->format_expr = e;
      return MATCH_YES;
    }

  gfc_current_locus = where;	/* The only case where we have to restore */

  return MATCH_NO;

conflict:
  gfc_error ("Duplicate format specification at %C");
  return MATCH_ERROR;
}


/* Traverse a namelist that is part of a READ statement to make sure
   that none of the variables in the namelist are INTENT(IN).  Returns
   nonzero if we find such a variable.  */

static int
check_namelist (gfc_symbol *sym)
{
  gfc_namelist *p;

  for (p = sym->namelist; p; p = p->next)
    if (p->sym->attr.intent == INTENT_IN)
      {
	gfc_error ("Symbol '%s' in namelist '%s' is INTENT(IN) at %C",
		   p->sym->name, sym->name);
	return 1;
      }

  return 0;
}


/* Match a single data transfer element.  */

static match
match_dt_element (io_kind k, gfc_dt *dt)
{
  char name[GFC_MAX_SYMBOL_LEN + 1];
  gfc_symbol *sym;
  match m;

  if (gfc_match (" unit =") == MATCH_YES)
    {
      m = match_dt_unit (k, dt);
      if (m != MATCH_NO)
	return m;
    }

  if (gfc_match (" fmt =") == MATCH_YES)
    {
      m = match_dt_format (dt);
      if (m != MATCH_NO)
	return m;
    }

  if (gfc_match (" nml = %n", name) == MATCH_YES)
    {
      if (dt->namelist != NULL)
	{
	  gfc_error ("Duplicate NML specification at %C");
	  return MATCH_ERROR;
	}

      if (gfc_find_symbol (name, NULL, 1, &sym))
	return MATCH_ERROR;

      if (sym == NULL || sym->attr.flavor != FL_NAMELIST)
	{
	  gfc_error ("Symbol '%s' at %C must be a NAMELIST group name",
		     sym != NULL ? sym->name : name);
	  return MATCH_ERROR;
	}

      dt->namelist = sym;
      if (k == M_READ && check_namelist (sym))
	return MATCH_ERROR;

      return MATCH_YES;
    }

  m = match_etag (&tag_e_async, &dt->asynchronous);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_blank, &dt->blank);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_delim, &dt->delim);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_pad, &dt->pad);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_sign, &dt->sign);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_round, &dt->round);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_id, &dt->id);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_e_decimal, &dt->decimal);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_rec, &dt->rec);
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_spos, &dt->pos);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iomsg, &dt->iomsg);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_iostat, &dt->iostat);
  if (m != MATCH_NO)
    return m;
  m = match_ltag (&tag_err, &dt->err);
  if (m == MATCH_YES)
    dt->err_where = gfc_current_locus;
  if (m != MATCH_NO)
    return m;
  m = match_etag (&tag_advance, &dt->advance);
  if (m != MATCH_NO)
    return m;
  m = match_out_tag (&tag_size, &dt->size);
  if (m != MATCH_NO)
    return m;

  m = match_ltag (&tag_end, &dt->end);
  if (m == MATCH_YES)
    {
      if (k == M_WRITE)
       {
	 gfc_error ("END tag at %C not allowed in output statement");
	 return MATCH_ERROR;
       }
      dt->end_where = gfc_current_locus;
    }
  if (m != MATCH_NO)
    return m;

  m = match_ltag (&tag_eor, &dt->eor);
  if (m == MATCH_YES)
    dt->eor_where = gfc_current_locus;
  if (m != MATCH_NO)
    return m;

  return MATCH_NO;
}


/* Free a data transfer structure and everything below it.  */

void
gfc_free_dt (gfc_dt *dt)
{
  if (dt == NULL)
    return;

  gfc_free_expr (dt->io_unit);
  gfc_free_expr (dt->format_expr);
  gfc_free_expr (dt->rec);
  gfc_free_expr (dt->advance);
  gfc_free_expr (dt->iomsg);
  gfc_free_expr (dt->iostat);
  gfc_free_expr (dt->size);
  gfc_free_expr (dt->pad);
  gfc_free_expr (dt->delim);
  gfc_free_expr (dt->sign);
  gfc_free_expr (dt->round);
  gfc_free_expr (dt->blank);
  gfc_free_expr (dt->decimal);
  gfc_free_expr (dt->pos);
  gfc_free_expr (dt->dt_io_kind);
  /* dt->extra_comma is a link to dt_io_kind if it is set.  */
  gfc_free (dt);
}


/* Resolve everything in a gfc_dt structure.  */

gfc_try
gfc_resolve_dt (gfc_dt *dt, locus *loc)
{
  gfc_expr *e;
  io_kind k;

  /* This is set in any case.  */
  gcc_assert (dt->dt_io_kind);
  k = dt->dt_io_kind->value.iokind;

  RESOLVE_TAG (&tag_format, dt->format_expr);
  RESOLVE_TAG (&tag_rec, dt->rec);
  RESOLVE_TAG (&tag_spos, dt->pos);
  RESOLVE_TAG (&tag_advance, dt->advance);
  RESOLVE_TAG (&tag_id, dt->id);
  RESOLVE_TAG (&tag_iomsg, dt->iomsg);
  RESOLVE_TAG (&tag_iostat, dt->iostat);
  RESOLVE_TAG (&tag_size, dt->size);
  RESOLVE_TAG (&tag_e_pad, dt->pad);
  RESOLVE_TAG (&tag_e_delim, dt->delim);
  RESOLVE_TAG (&tag_e_sign, dt->sign);
  RESOLVE_TAG (&tag_e_round, dt->round);
  RESOLVE_TAG (&tag_e_blank, dt->blank);
  RESOLVE_TAG (&tag_e_decimal, dt->decimal);
  RESOLVE_TAG (&tag_e_async, dt->asynchronous);

  e = dt->io_unit;
  if (e == NULL)
    {
      gfc_error ("UNIT not specified at %L", loc);
      return FAILURE;
    }

  if (gfc_resolve_expr (e) == SUCCESS
      && (e->ts.type != BT_INTEGER
	  && (e->ts.type != BT_CHARACTER || e->expr_type != EXPR_VARIABLE)))
    {
      /* If there is no extra comma signifying the "format" form of the IO
	 statement, then this must be an error.  */
      if (!dt->extra_comma)
	{
	  gfc_error ("UNIT specification at %L must be an INTEGER expression "
		     "or a CHARACTER variable", &e->where);
	  return FAILURE;
	}
      else
	{
	  /* At this point, we have an extra comma.  If io_unit has arrived as
	     type character, we assume its really the "format" form of the I/O
	     statement.  We set the io_unit to the default unit and format to
	     the character expression.  See F95 Standard section 9.4.  */
	  if (e->ts.type == BT_CHARACTER && (k == M_READ || k == M_PRINT))
	    {
	      dt->format_expr = dt->io_unit;
	      dt->io_unit = default_unit (k);

	      /* Nullify this pointer now so that a warning/error is not
		 triggered below for the "Extension".  */
	      dt->extra_comma = NULL;
	    }

	  if (k == M_WRITE)
	    {
	      gfc_error ("Invalid form of WRITE statement at %L, UNIT required",
			 &dt->extra_comma->where);
	      return FAILURE;
	    }
	}
    }

  if (e->ts.type == BT_CHARACTER)
    {
      if (gfc_has_vector_index (e))
	{
	  gfc_error ("Internal unit with vector subscript at %L", &e->where);
	  return FAILURE;
	}

      /* If we are writing, make sure the internal unit can be changed.  */
      gcc_assert (k != M_PRINT);
      if (k == M_WRITE
	  && gfc_check_vardef_context (e, false, _("internal unit in WRITE"))
	       == FAILURE)
	return FAILURE;
    }

  if (e->rank && e->ts.type != BT_CHARACTER)
    {
      gfc_error ("External IO UNIT cannot be an array at %L", &e->where);
      return FAILURE;
    }

  if (e->expr_type == EXPR_CONSTANT && e->ts.type == BT_INTEGER
      && mpz_sgn (e->value.integer) < 0)
    {
      gfc_error ("UNIT number in statement at %L must be non-negative",
		 &e->where);
      return FAILURE;
    }

  /* If we are reading and have a namelist, check that all namelist symbols
     can appear in a variable definition context.  */
  if (k == M_READ && dt->namelist)
    {
      gfc_namelist* n;
      for (n = dt->namelist->namelist; n; n = n->next)
	{
	  gfc_expr* e;
	  gfc_try t;

	  e = gfc_get_variable_expr (gfc_find_sym_in_symtree (n->sym));
	  t = gfc_check_vardef_context (e, false, NULL);
	  gfc_free_expr (e);

	  if (t == FAILURE)
	    {
	      gfc_error ("NAMELIST '%s' in READ statement at %L contains"
			 " the symbol '%s' which may not appear in a"
			 " variable definition context",
			 dt->namelist->name, loc, n->sym->name);
	      return FAILURE;
	    }
	}
    }

  if (dt->extra_comma
      && gfc_notify_std (GFC_STD_GNU, "Extension: Comma before i/o "
			 "item list at %L", &dt->extra_comma->where) == FAILURE)
    return FAILURE;

  if (dt->err)
    {
      if (gfc_reference_st_label (dt->err, ST_LABEL_TARGET) == FAILURE)
	return FAILURE;
      if (dt->err->defined == ST_LABEL_UNKNOWN)
	{
	  gfc_error ("ERR tag label %d at %L not defined",
		      dt->err->value, &dt->err_where);
	  return FAILURE;
	}
    }

  if (dt->end)
    {
      if (gfc_reference_st_label (dt->end, ST_LABEL_TARGET) == FAILURE)
	return FAILURE;
      if (dt->end->defined == ST_LABEL_UNKNOWN)
	{
	  gfc_error ("END tag label %d at %L not defined",
		      dt->end->value, &dt->end_where);
	  return FAILURE;
	}
    }

  if (dt->eor)
    {
      if (gfc_reference_st_label (dt->eor, ST_LABEL_TARGET) == FAILURE)
	return FAILURE;
      if (dt->eor->defined == ST_LABEL_UNKNOWN)
	{
	  gfc_error ("EOR tag label %d at %L not defined",
		      dt->eor->value, &dt->eor_where);
	  return FAILURE;
	}
    }

  /* Check the format label actually exists.  */
  if (dt->format_label && dt->format_label != &format_asterisk
      && dt->format_label->defined == ST_LABEL_UNKNOWN)
    {
      gfc_error ("FORMAT label %d at %L not defined", dt->format_label->value,
		 &dt->format_label->where);
      return FAILURE;
    }

  return SUCCESS;
}


/* Given an io_kind, return its name.  */

static const char *
io_kind_name (io_kind k)
{
  const char *name;

  switch (k)
    {
    case M_READ:
      name = "READ";
      break;
    case M_WRITE:
      name = "WRITE";
      break;
    case M_PRINT:
      name = "PRINT";
      break;
    case M_INQUIRE:
      name = "INQUIRE";
      break;
    default:
      gfc_internal_error ("io_kind_name(): bad I/O-kind");
    }

  return name;
}


/* Match an IO iteration statement of the form:

   ( [<IO element> ,] <IO element>, I = <expr>, <expr> [, <expr> ] )

   which is equivalent to a single IO element.  This function is
   mutually recursive with match_io_element().  */

static match match_io_element (io_kind, gfc_code **);

static match
match_io_iterator (io_kind k, gfc_code **result)
{
  gfc_code *head, *tail, *new_code;
  gfc_iterator *iter;
  locus old_loc;
  match m;
  int n;

  iter = NULL;
  head = NULL;
  old_loc = gfc_current_locus;

  if (gfc_match_char ('(') != MATCH_YES)
    return MATCH_NO;

  m = match_io_element (k, &head);
  tail = head;

  if (m != MATCH_YES || gfc_match_char (',') != MATCH_YES)
    {
      m = MATCH_NO;
      goto cleanup;
    }

  /* Can't be anything but an IO iterator.  Build a list.  */
  iter = gfc_get_iterator ();

  for (n = 1;; n++)
    {
      m = gfc_match_iterator (iter, 0);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_YES)
	{
	  gfc_check_do_variable (iter->var->symtree);
	  break;
	}

      m = match_io_element (k, &new_code);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	{
	  if (n > 2)
	    goto syntax;
	  goto cleanup;
	}

      tail = gfc_append_code (tail, new_code);

      if (gfc_match_char (',') != MATCH_YES)
	{
	  if (n > 2)
	    goto syntax;
	  m = MATCH_NO;
	  goto cleanup;
	}
    }

  if (gfc_match_char (')') != MATCH_YES)
    goto syntax;

  new_code = gfc_get_code ();
  new_code->op = EXEC_DO;
  new_code->ext.iterator = iter;

  new_code->block = gfc_get_code ();
  new_code->block->op = EXEC_DO;
  new_code->block->next = head;

  *result = new_code;
  return MATCH_YES;

syntax:
  gfc_error ("Syntax error in I/O iterator at %C");
  m = MATCH_ERROR;

cleanup:
  gfc_free_iterator (iter, 1);
  gfc_free_statements (head);
  gfc_current_locus = old_loc;
  return m;
}


/* Match a single element of an IO list, which is either a single
   expression or an IO Iterator.  */

static match
match_io_element (io_kind k, gfc_code **cpp)
{
  gfc_expr *expr;
  gfc_code *cp;
  match m;

  expr = NULL;

  m = match_io_iterator (k, cpp);
  if (m == MATCH_YES)
    return MATCH_YES;

  if (k == M_READ)
    {
      m = gfc_match_variable (&expr, 0);
      if (m == MATCH_NO)
	gfc_error ("Expected variable in READ statement at %C");
    }
  else
    {
      m = gfc_match_expr (&expr);
      if (m == MATCH_NO)
	gfc_error ("Expected expression in %s statement at %C",
		   io_kind_name (k));
    }

  if (m == MATCH_YES && k == M_READ && gfc_check_do_variable (expr->symtree))
    m = MATCH_ERROR;

  if (m != MATCH_YES)
    {
      gfc_free_expr (expr);
      return MATCH_ERROR;
    }

  cp = gfc_get_code ();
  cp->op = EXEC_TRANSFER;
  cp->expr1 = expr;
  if (k != M_INQUIRE)
    cp->ext.dt = current_dt;

  *cpp = cp;
  return MATCH_YES;
}


/* Match an I/O list, building gfc_code structures as we go.  */

static match
match_io_list (io_kind k, gfc_code **head_p)
{
  gfc_code *head, *tail, *new_code;
  match m;

  *head_p = head = tail = NULL;
  if (gfc_match_eos () == MATCH_YES)
    return MATCH_YES;

  for (;;)
    {
      m = match_io_element (k, &new_code);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;

      tail = gfc_append_code (tail, new_code);
      if (head == NULL)
	head = new_code;

      if (gfc_match_eos () == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;
    }

  *head_p = head;
  return MATCH_YES;

syntax:
  gfc_error ("Syntax error in %s statement at %C", io_kind_name (k));

cleanup:
  gfc_free_statements (head);
  return MATCH_ERROR;
}


/* Attach the data transfer end node.  */

static void
terminate_io (gfc_code *io_code)
{
  gfc_code *c;

  if (io_code == NULL)
    io_code = new_st.block;

  c = gfc_get_code ();
  c->op = EXEC_DT_END;

  /* Point to structure that is already there */
  c->ext.dt = new_st.ext.dt;
  gfc_append_code (io_code, c);
}


/* Check the constraints for a data transfer statement.  The majority of the
   constraints appearing in 9.4 of the standard appear here.  Some are handled
   in resolve_tag and others in gfc_resolve_dt.  */

static match
check_io_constraints (io_kind k, gfc_dt *dt, gfc_code *io_code,
		      locus *spec_end)
{
#define io_constraint(condition,msg,arg)\
if (condition) \
  {\
    gfc_error(msg,arg);\
    m = MATCH_ERROR;\
  }

  match m;
  gfc_expr *expr;
  gfc_symbol *sym = NULL;
  bool warn, unformatted;

  warn = (dt->err || dt->iostat) ? true : false;
  unformatted = dt->format_expr == NULL && dt->format_label == NULL
		&& dt->namelist == NULL;

  m = MATCH_YES;

  expr = dt->io_unit;
  if (expr && expr->expr_type == EXPR_VARIABLE
      && expr->ts.type == BT_CHARACTER)
    {
      sym = expr->symtree->n.sym;

      io_constraint (k == M_WRITE && sym->attr.intent == INTENT_IN,
		     "Internal file at %L must not be INTENT(IN)",
		     &expr->where);

      io_constraint (gfc_has_vector_index (dt->io_unit),
		     "Internal file incompatible with vector subscript at %L",
		     &expr->where);

      io_constraint (dt->rec != NULL,
		     "REC tag at %L is incompatible with internal file",
		     &dt->rec->where);
    
      io_constraint (dt->pos != NULL,
		     "POS tag at %L is incompatible with internal file",
		     &dt->pos->where);

      io_constraint (unformatted,
		     "Unformatted I/O not allowed with internal unit at %L",
		     &dt->io_unit->where);

      io_constraint (dt->asynchronous != NULL,
		     "ASYNCHRONOUS tag at %L not allowed with internal file",
		     &dt->asynchronous->where);

      if (dt->namelist != NULL)
	{
	  if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: Internal file "
			      "at %L with namelist", &expr->where)
	      == FAILURE)
	    m = MATCH_ERROR;
	}

      io_constraint (dt->advance != NULL,
		     "ADVANCE tag at %L is incompatible with internal file",
		     &dt->advance->where);
    }

  if (expr && expr->ts.type != BT_CHARACTER)
    {

      io_constraint (gfc_pure (NULL) && (k == M_READ || k == M_WRITE),
		     "IO UNIT in %s statement at %C must be "
		     "an internal file in a PURE procedure",
		     io_kind_name (k));

      if (gfc_implicit_pure (NULL) && (k == M_READ || k == M_WRITE))
	gfc_current_ns->proc_name->attr.implicit_pure = 0;

    }

  if (k != M_READ)
    {
      io_constraint (dt->end, "END tag not allowed with output at %L",
		     &dt->end_where);

      io_constraint (dt->eor, "EOR tag not allowed with output at %L",
		     &dt->eor_where);

      io_constraint (dt->blank, "BLANK= specifier not allowed with output at %L",
		     &dt->blank->where);

      io_constraint (dt->pad, "PAD= specifier not allowed with output at %L",
		     &dt->pad->where);

      io_constraint (dt->size, "SIZE= specifier not allowed with output at %L",
		     &dt->size->where);
    }
  else
    {
      io_constraint (dt->size && dt->advance == NULL,
		     "SIZE tag at %L requires an ADVANCE tag",
		     &dt->size->where);

      io_constraint (dt->eor && dt->advance == NULL,
		     "EOR tag at %L requires an ADVANCE tag",
		     &dt->eor_where);
    }

  if (dt->asynchronous) 
    {
      static const char * asynchronous[] = { "YES", "NO", NULL };

      if (gfc_reduce_init_expr (dt->asynchronous) != SUCCESS)
	{
	  gfc_error ("ASYNCHRONOUS= specifier at %L must be an initialization "
		     "expression", &dt->asynchronous->where);
	  return MATCH_ERROR;
	}

      if (!compare_to_allowed_values
		("ASYNCHRONOUS", asynchronous, NULL, NULL,
		 dt->asynchronous->value.character.string,
		 io_kind_name (k), warn))
	return MATCH_ERROR;
    }

  if (dt->id)
    {
      bool not_yes
	= !dt->asynchronous
	  || gfc_wide_strlen (dt->asynchronous->value.character.string) != 3
	  || gfc_wide_strncasecmp (dt->asynchronous->value.character.string,
				   "yes", 3) != 0;
      io_constraint (not_yes,
		     "ID= specifier at %L must be with ASYNCHRONOUS='yes' "
		     "specifier", &dt->id->where);
    }

  if (dt->decimal)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DECIMAL= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;

      if (dt->decimal->expr_type == EXPR_CONSTANT)
	{
	  static const char * decimal[] = { "COMMA", "POINT", NULL };

	  if (!compare_to_allowed_values ("DECIMAL", decimal, NULL, NULL,
					  dt->decimal->value.character.string,
					  io_kind_name (k), warn))
	    return MATCH_ERROR;

	  io_constraint (unformatted,
			 "the DECIMAL= specifier at %L must be with an "
			 "explicit format expression", &dt->decimal->where);
	}
    }
  
  if (dt->blank)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: BLANK= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;

      if (dt->blank->expr_type == EXPR_CONSTANT)
	{
	  static const char * blank[] = { "NULL", "ZERO", NULL };

	  if (!compare_to_allowed_values ("BLANK", blank, NULL, NULL,
					  dt->blank->value.character.string,
					  io_kind_name (k), warn))
	    return MATCH_ERROR;

	  io_constraint (unformatted,
			 "the BLANK= specifier at %L must be with an "
			 "explicit format expression", &dt->blank->where);
	}
    }

  if (dt->pad)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: PAD= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;

      if (dt->pad->expr_type == EXPR_CONSTANT)
	{
	  static const char * pad[] = { "YES", "NO", NULL };

	  if (!compare_to_allowed_values ("PAD", pad, NULL, NULL,
					  dt->pad->value.character.string,
					  io_kind_name (k), warn))
	    return MATCH_ERROR;

	  io_constraint (unformatted,
			 "the PAD= specifier at %L must be with an "
			 "explicit format expression", &dt->pad->where);
	}
    }

  if (dt->round)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: ROUND= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;

      if (dt->round->expr_type == EXPR_CONSTANT)
	{
	  static const char * round[] = { "UP", "DOWN", "ZERO", "NEAREST",
					  "COMPATIBLE", "PROCESSOR_DEFINED",
					  NULL };

	  if (!compare_to_allowed_values ("ROUND", round, NULL, NULL,
					  dt->round->value.character.string,
					  io_kind_name (k), warn))
	    return MATCH_ERROR;
	}
    }
  
  if (dt->sign)
    {
      /* When implemented, change the following to use gfc_notify_std F2003.
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: SIGN= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;  */
      if (dt->sign->expr_type == EXPR_CONSTANT)
	{
	  static const char * sign[] = { "PLUS", "SUPPRESS", "PROCESSOR_DEFINED",
					 NULL };

	  if (!compare_to_allowed_values ("SIGN", sign, NULL, NULL,
				      dt->sign->value.character.string,
				      io_kind_name (k), warn))
	    return MATCH_ERROR;

	  io_constraint (unformatted,
			 "SIGN= specifier at %L must be with an "
			 "explicit format expression", &dt->sign->where);

	  io_constraint (k == M_READ,
			 "SIGN= specifier at %L not allowed in a "
			 "READ statement", &dt->sign->where);
	}
    }

  if (dt->delim)
    {
      if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: DELIM= at %C "
	  "not allowed in Fortran 95") == FAILURE)
	return MATCH_ERROR;

      if (dt->delim->expr_type == EXPR_CONSTANT)
	{
	  static const char *delim[] = { "APOSTROPHE", "QUOTE", "NONE", NULL };

	  if (!compare_to_allowed_values ("DELIM", delim, NULL, NULL,
					  dt->delim->value.character.string,
					  io_kind_name (k), warn))
	    return MATCH_ERROR;

	  io_constraint (k == M_READ,
			 "DELIM= specifier at %L not allowed in a "
			 "READ statement", &dt->delim->where);
      
	  io_constraint (dt->format_label != &format_asterisk
			 && dt->namelist == NULL,
			 "DELIM= specifier at %L must have FMT=*",
			 &dt->delim->where);

	  io_constraint (unformatted && dt->namelist == NULL,
			 "DELIM= specifier at %L must be with FMT=* or "
			 "NML= specifier ", &dt->delim->where);
	}
    }
  
  if (dt->namelist)
    {
      io_constraint (io_code && dt->namelist,
		     "NAMELIST cannot be followed by IO-list at %L",
		     &io_code->loc);

      io_constraint (dt->format_expr,
		     "IO spec-list cannot contain both NAMELIST group name "
		     "and format specification at %L",
		     &dt->format_expr->where);

      io_constraint (dt->format_label,
		     "IO spec-list cannot contain both NAMELIST group name "
		     "and format label at %L", spec_end);

      io_constraint (dt->rec,
		     "NAMELIST IO is not allowed with a REC= specifier "
		     "at %L", &dt->rec->where);

      io_constraint (dt->advance,
		     "NAMELIST IO is not allowed with a ADVANCE= specifier "
		     "at %L", &dt->advance->where);
    }

  if (dt->rec)
    {
      io_constraint (dt->end,
		     "An END tag is not allowed with a "
		     "REC= specifier at %L", &dt->end_where);

      io_constraint (dt->format_label == &format_asterisk,
		     "FMT=* is not allowed with a REC= specifier "
		     "at %L", spec_end);

      io_constraint (dt->pos,
		     "POS= is not allowed with REC= specifier "
		     "at %L", &dt->pos->where);
    }

  if (dt->advance)
    {
      int not_yes, not_no;
      expr = dt->advance;

      io_constraint (dt->format_label == &format_asterisk,
		     "List directed format(*) is not allowed with a "
		     "ADVANCE= specifier at %L.", &expr->where);

      io_constraint (unformatted,
		     "the ADVANCE= specifier at %L must appear with an "
		     "explicit format expression", &expr->where);

      if (expr->expr_type == EXPR_CONSTANT && expr->ts.type == BT_CHARACTER)
	{
	  const gfc_char_t *advance = expr->value.character.string;
	  not_no = gfc_wide_strlen (advance) != 2
		   || gfc_wide_strncasecmp (advance, "no", 2) != 0;
	  not_yes = gfc_wide_strlen (advance) != 3
		    || gfc_wide_strncasecmp (advance, "yes", 3) != 0;
	}
      else
	{
	  not_no = 0;
	  not_yes = 0;
	}

      io_constraint (not_no && not_yes,
		     "ADVANCE= specifier at %L must have value = "
		     "YES or NO.", &expr->where);

      io_constraint (dt->size && not_no && k == M_READ,
		     "SIZE tag at %L requires an ADVANCE = 'NO'",
		     &dt->size->where);

      io_constraint (dt->eor && not_no && k == M_READ,
		     "EOR tag at %L requires an ADVANCE = 'NO'",
		     &dt->eor_where);      
    }

  expr = dt->format_expr;
  if (gfc_simplify_expr (expr, 0) == FAILURE
      || check_format_string (expr, k == M_READ) == FAILURE)
    return MATCH_ERROR;

  return m;
}
#undef io_constraint


/* Match a READ, WRITE or PRINT statement.  */

static match
match_io (io_kind k)
{
  char name[GFC_MAX_SYMBOL_LEN + 1];
  gfc_code *io_code;
  gfc_symbol *sym;
  int comma_flag;
  locus where;
  locus spec_end;
  gfc_dt *dt;
  match m;

  where = gfc_current_locus;
  comma_flag = 0;
  current_dt = dt = XCNEW (gfc_dt);
  m = gfc_match_char ('(');
  if (m == MATCH_NO)
    {
      where = gfc_current_locus;
      if (k == M_WRITE)
	goto syntax;
      else if (k == M_PRINT)
	{
	  /* Treat the non-standard case of PRINT namelist.  */
	  if ((gfc_current_form == FORM_FIXED || gfc_peek_ascii_char () == ' ')
	      && gfc_match_name (name) == MATCH_YES)
	    {
	      gfc_find_symbol (name, NULL, 1, &sym);
	      if (sym && sym->attr.flavor == FL_NAMELIST)
		{
		  if (gfc_notify_std (GFC_STD_GNU, "PRINT namelist at "
				      "%C is an extension") == FAILURE)
		    {
		      m = MATCH_ERROR;
		      goto cleanup;
		    }

		  dt->io_unit = default_unit (k);
		  dt->namelist = sym;
		  goto get_io_list;
		}
	      else
		gfc_current_locus = where;
	    }
	}

      if (gfc_current_form == FORM_FREE)
	{
	  char c = gfc_peek_ascii_char ();
	  if (c != ' ' && c != '*' && c != '\'' && c != '"')
	    {
	      m = MATCH_NO;
	      goto cleanup;
	    }
	}

      m = match_dt_format (dt);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;

      comma_flag = 1;
      dt->io_unit = default_unit (k);
      goto get_io_list;
    }
  else
    {
      /* Before issuing an error for a malformed 'print (1,*)' type of
	 error, check for a default-char-expr of the form ('(I0)').  */
      if (k == M_PRINT && m == MATCH_YES)
	{
	  /* Reset current locus to get the initial '(' in an expression.  */
	  gfc_current_locus = where;
	  dt->format_expr = NULL;
	  m = match_dt_format (dt);

	  if (m == MATCH_ERROR)
	    goto cleanup;
	  if (m == MATCH_NO || dt->format_expr == NULL)
	    goto syntax;

	  comma_flag = 1;
	  dt->io_unit = default_unit (k);
	  goto get_io_list;
	}
    }

  /* Match a control list */
  if (match_dt_element (k, dt) == MATCH_YES)
    goto next;
  if (match_dt_unit (k, dt) != MATCH_YES)
    goto loop;

  if (gfc_match_char (')') == MATCH_YES)
    goto get_io_list;
  if (gfc_match_char (',') != MATCH_YES)
    goto syntax;

  m = match_dt_element (k, dt);
  if (m == MATCH_YES)
    goto next;
  if (m == MATCH_ERROR)
    goto cleanup;

  m = match_dt_format (dt);
  if (m == MATCH_YES)
    goto next;
  if (m == MATCH_ERROR)
    goto cleanup;

  where = gfc_current_locus;

  m = gfc_match_name (name);
  if (m == MATCH_YES)
    {
      gfc_find_symbol (name, NULL, 1, &sym);
      if (sym && sym->attr.flavor == FL_NAMELIST)
	{
	  dt->namelist = sym;
	  if (k == M_READ && check_namelist (sym))
	    {
	      m = MATCH_ERROR;
	      goto cleanup;
	    }
	  goto next;
	}
    }

  gfc_current_locus = where;

  goto loop;			/* No matches, try regular elements */

next:
  if (gfc_match_char (')') == MATCH_YES)
    goto get_io_list;
  if (gfc_match_char (',') != MATCH_YES)
    goto syntax;

loop:
  for (;;)
    {
      m = match_dt_element (k, dt);
      if (m == MATCH_NO)
	goto syntax;
      if (m == MATCH_ERROR)
	goto cleanup;

      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;
    }

get_io_list:

  /* Used in check_io_constraints, where no locus is available.  */
  spec_end = gfc_current_locus;

  /* Save the IO kind for later use.  */
  dt->dt_io_kind = gfc_get_iokind_expr (&gfc_current_locus, k);

  /* Optional leading comma (non-standard).  We use a gfc_expr structure here
     to save the locus.  This is used later when resolving transfer statements
     that might have a format expression without unit number.  */
  if (!comma_flag && gfc_match_char (',') == MATCH_YES)
    dt->extra_comma = dt->dt_io_kind;

  io_code = NULL;
  if (gfc_match_eos () != MATCH_YES)
    {
      if (comma_flag && gfc_match_char (',') != MATCH_YES)
	{
	  gfc_error ("Expected comma in I/O list at %C");
	  m = MATCH_ERROR;
	  goto cleanup;
	}

      m = match_io_list (k, &io_code);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  /* A full IO statement has been matched.  Check the constraints.  spec_end is
     supplied for cases where no locus is supplied.  */
  m = check_io_constraints (k, dt, io_code, &spec_end);

  if (m == MATCH_ERROR)
    goto cleanup;

  new_st.op = (k == M_READ) ? EXEC_READ : EXEC_WRITE;
  new_st.ext.dt = dt;
  new_st.block = gfc_get_code ();
  new_st.block->op = new_st.op;
  new_st.block->next = io_code;

  terminate_io (io_code);

  return MATCH_YES;

syntax:
  gfc_error ("Syntax error in %s statement at %C", io_kind_name (k));
  m = MATCH_ERROR;

cleanup:
  gfc_free_dt (dt);
  return m;
}


match
gfc_match_read (void)
{
  return match_io (M_READ);
}


match
gfc_match_write (void)
{
  return match_io (M_WRITE);
}


match
gfc_match_print (void)
{
  match m;

  m = match_io (M_PRINT);
  if (m != MATCH_YES)
    return m;

  if (gfc_pure (NULL))
    {
      gfc_error ("PRINT statement at %C not allowed within PURE procedure");
      return MATCH_ERROR;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  return MATCH_YES;
}


/* Free a gfc_inquire structure.  */

void
gfc_free_inquire (gfc_inquire *inquire)
{

  if (inquire == NULL)
    return;

  gfc_free_expr (inquire->unit);
  gfc_free_expr (inquire->file);
  gfc_free_expr (inquire->iomsg);
  gfc_free_expr (inquire->iostat);
  gfc_free_expr (inquire->exist);
  gfc_free_expr (inquire->opened);
  gfc_free_expr (inquire->number);
  gfc_free_expr (inquire->named);
  gfc_free_expr (inquire->name);
  gfc_free_expr (inquire->access);
  gfc_free_expr (inquire->sequential);
  gfc_free_expr (inquire->direct);
  gfc_free_expr (inquire->form);
  gfc_free_expr (inquire->formatted);
  gfc_free_expr (inquire->unformatted);
  gfc_free_expr (inquire->recl);
  gfc_free_expr (inquire->nextrec);
  gfc_free_expr (inquire->blank);
  gfc_free_expr (inquire->position);
  gfc_free_expr (inquire->action);
  gfc_free_expr (inquire->read);
  gfc_free_expr (inquire->write);
  gfc_free_expr (inquire->readwrite);
  gfc_free_expr (inquire->delim);
  gfc_free_expr (inquire->encoding);
  gfc_free_expr (inquire->pad);
  gfc_free_expr (inquire->iolength);
  gfc_free_expr (inquire->convert);
  gfc_free_expr (inquire->strm_pos);
  gfc_free_expr (inquire->asynchronous);
  gfc_free_expr (inquire->decimal);
  gfc_free_expr (inquire->pending);
  gfc_free_expr (inquire->id);
  gfc_free_expr (inquire->sign);
  gfc_free_expr (inquire->size);
  gfc_free_expr (inquire->round);
  gfc_free (inquire);
}


/* Match an element of an INQUIRE statement.  */

#define RETM   if (m != MATCH_NO) return m;

static match
match_inquire_element (gfc_inquire *inquire)
{
  match m;

  m = match_etag (&tag_unit, &inquire->unit);
  RETM m = match_etag (&tag_file, &inquire->file);
  RETM m = match_ltag (&tag_err, &inquire->err);
  RETM m = match_out_tag (&tag_iomsg, &inquire->iomsg);
  RETM m = match_out_tag (&tag_iostat, &inquire->iostat);
  RETM m = match_vtag (&tag_exist, &inquire->exist);
  RETM m = match_vtag (&tag_opened, &inquire->opened);
  RETM m = match_vtag (&tag_named, &inquire->named);
  RETM m = match_vtag (&tag_name, &inquire->name);
  RETM m = match_out_tag (&tag_number, &inquire->number);
  RETM m = match_vtag (&tag_s_access, &inquire->access);
  RETM m = match_vtag (&tag_sequential, &inquire->sequential);
  RETM m = match_vtag (&tag_direct, &inquire->direct);
  RETM m = match_vtag (&tag_s_form, &inquire->form);
  RETM m = match_vtag (&tag_formatted, &inquire->formatted);
  RETM m = match_vtag (&tag_unformatted, &inquire->unformatted);
  RETM m = match_out_tag (&tag_s_recl, &inquire->recl);
  RETM m = match_out_tag (&tag_nextrec, &inquire->nextrec);
  RETM m = match_vtag (&tag_s_blank, &inquire->blank);
  RETM m = match_vtag (&tag_s_position, &inquire->position);
  RETM m = match_vtag (&tag_s_action, &inquire->action);
  RETM m = match_vtag (&tag_read, &inquire->read);
  RETM m = match_vtag (&tag_write, &inquire->write);
  RETM m = match_vtag (&tag_readwrite, &inquire->readwrite);
  RETM m = match_vtag (&tag_s_async, &inquire->asynchronous);
  RETM m = match_vtag (&tag_s_delim, &inquire->delim);
  RETM m = match_vtag (&tag_s_decimal, &inquire->decimal);
  RETM m = match_vtag (&tag_size, &inquire->size);
  RETM m = match_vtag (&tag_s_encoding, &inquire->encoding);
  RETM m = match_vtag (&tag_s_round, &inquire->round);
  RETM m = match_vtag (&tag_s_sign, &inquire->sign);
  RETM m = match_vtag (&tag_s_pad, &inquire->pad);
  RETM m = match_vtag (&tag_iolength, &inquire->iolength);
  RETM m = match_vtag (&tag_convert, &inquire->convert);
  RETM m = match_out_tag (&tag_strm_out, &inquire->strm_pos);
  RETM m = match_vtag (&tag_pending, &inquire->pending);
  RETM m = match_vtag (&tag_id, &inquire->id);
  RETM return MATCH_NO;
}

#undef RETM


match
gfc_match_inquire (void)
{
  gfc_inquire *inquire;
  gfc_code *code;
  match m;
  locus loc;

  m = gfc_match_char ('(');
  if (m == MATCH_NO)
    return m;

  inquire = XCNEW (gfc_inquire);

  loc = gfc_current_locus;

  m = match_inquire_element (inquire);
  if (m == MATCH_ERROR)
    goto cleanup;
  if (m == MATCH_NO)
    {
      m = gfc_match_expr (&inquire->unit);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  /* See if we have the IOLENGTH form of the inquire statement.  */
  if (inquire->iolength != NULL)
    {
      if (gfc_match_char (')') != MATCH_YES)
	goto syntax;

      m = match_io_list (M_INQUIRE, &code);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;

      new_st.op = EXEC_IOLENGTH;
      new_st.expr1 = inquire->iolength;
      new_st.ext.inquire = inquire;

      if (gfc_pure (NULL))
	{
	  gfc_free_statements (code);
	  gfc_error ("INQUIRE statement not allowed in PURE procedure at %C");
	  return MATCH_ERROR;
	}

      if (gfc_implicit_pure (NULL))
	gfc_current_ns->proc_name->attr.implicit_pure = 0;

      new_st.block = gfc_get_code ();
      new_st.block->op = EXEC_IOLENGTH;
      terminate_io (code);
      new_st.block->next = code;
      return MATCH_YES;
    }

  /* At this point, we have the non-IOLENGTH inquire statement.  */
  for (;;)
    {
      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;

      m = match_inquire_element (inquire);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;

      if (inquire->iolength != NULL)
	{
	  gfc_error ("IOLENGTH tag invalid in INQUIRE statement at %C");
	  goto cleanup;
	}
    }

  if (gfc_match_eos () != MATCH_YES)
    goto syntax;

  if (inquire->unit != NULL && inquire->file != NULL)
    {
      gfc_error ("INQUIRE statement at %L cannot contain both FILE and "
		 "UNIT specifiers", &loc);
      goto cleanup;
    }

  if (inquire->unit == NULL && inquire->file == NULL)
    {
      gfc_error ("INQUIRE statement at %L requires either FILE or "
		 "UNIT specifier", &loc);
      goto cleanup;
    }

  if (gfc_pure (NULL))
    {
      gfc_error ("INQUIRE statement not allowed in PURE procedure at %C");
      goto cleanup;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;
  
  if (inquire->id != NULL && inquire->pending == NULL)
    {
      gfc_error ("INQUIRE statement at %L requires a PENDING= specifier with "
		 "the ID= specifier", &loc);
      goto cleanup;
    }

  new_st.op = EXEC_INQUIRE;
  new_st.ext.inquire = inquire;
  return MATCH_YES;

syntax:
  gfc_syntax_error (ST_INQUIRE);

cleanup:
  gfc_free_inquire (inquire);
  return MATCH_ERROR;
}


/* Resolve everything in a gfc_inquire structure.  */

gfc_try
gfc_resolve_inquire (gfc_inquire *inquire)
{
  RESOLVE_TAG (&tag_unit, inquire->unit);
  RESOLVE_TAG (&tag_file, inquire->file);
  RESOLVE_TAG (&tag_id, inquire->id);

  /* For INQUIRE, all tags except FILE, ID and UNIT are variable definition
     contexts.  Thus, use an extended RESOLVE_TAG macro for that.  */
#define INQUIRE_RESOLVE_TAG(tag, expr) \
  RESOLVE_TAG (tag, expr); \
  if (expr) \
    { \
      char context[64]; \
      sprintf (context, _("%s tag with INQUIRE"), (tag)->name); \
      if (gfc_check_vardef_context ((expr), false, context) == FAILURE) \
	return FAILURE; \
    }
  INQUIRE_RESOLVE_TAG (&tag_iomsg, inquire->iomsg);
  INQUIRE_RESOLVE_TAG (&tag_iostat, inquire->iostat);
  INQUIRE_RESOLVE_TAG (&tag_exist, inquire->exist);
  INQUIRE_RESOLVE_TAG (&tag_opened, inquire->opened);
  INQUIRE_RESOLVE_TAG (&tag_number, inquire->number);
  INQUIRE_RESOLVE_TAG (&tag_named, inquire->named);
  INQUIRE_RESOLVE_TAG (&tag_name, inquire->name);
  INQUIRE_RESOLVE_TAG (&tag_s_access, inquire->access);
  INQUIRE_RESOLVE_TAG (&tag_sequential, inquire->sequential);
  INQUIRE_RESOLVE_TAG (&tag_direct, inquire->direct);
  INQUIRE_RESOLVE_TAG (&tag_s_form, inquire->form);
  INQUIRE_RESOLVE_TAG (&tag_formatted, inquire->formatted);
  INQUIRE_RESOLVE_TAG (&tag_unformatted, inquire->unformatted);
  INQUIRE_RESOLVE_TAG (&tag_s_recl, inquire->recl);
  INQUIRE_RESOLVE_TAG (&tag_nextrec, inquire->nextrec);
  INQUIRE_RESOLVE_TAG (&tag_s_blank, inquire->blank);
  INQUIRE_RESOLVE_TAG (&tag_s_position, inquire->position);
  INQUIRE_RESOLVE_TAG (&tag_s_action, inquire->action);
  INQUIRE_RESOLVE_TAG (&tag_read, inquire->read);
  INQUIRE_RESOLVE_TAG (&tag_write, inquire->write);
  INQUIRE_RESOLVE_TAG (&tag_readwrite, inquire->readwrite);
  INQUIRE_RESOLVE_TAG (&tag_s_delim, inquire->delim);
  INQUIRE_RESOLVE_TAG (&tag_s_pad, inquire->pad);
  INQUIRE_RESOLVE_TAG (&tag_s_encoding, inquire->encoding);
  INQUIRE_RESOLVE_TAG (&tag_s_round, inquire->round);
  INQUIRE_RESOLVE_TAG (&tag_iolength, inquire->iolength);
  INQUIRE_RESOLVE_TAG (&tag_convert, inquire->convert);
  INQUIRE_RESOLVE_TAG (&tag_strm_out, inquire->strm_pos);
  INQUIRE_RESOLVE_TAG (&tag_s_async, inquire->asynchronous);
  INQUIRE_RESOLVE_TAG (&tag_s_sign, inquire->sign);
  INQUIRE_RESOLVE_TAG (&tag_s_round, inquire->round);
  INQUIRE_RESOLVE_TAG (&tag_pending, inquire->pending);
  INQUIRE_RESOLVE_TAG (&tag_size, inquire->size);
#undef INQUIRE_RESOLVE_TAG

  if (gfc_reference_st_label (inquire->err, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;

  return SUCCESS;
}


void
gfc_free_wait (gfc_wait *wait)
{
  if (wait == NULL)
    return;

  gfc_free_expr (wait->unit);
  gfc_free_expr (wait->iostat);
  gfc_free_expr (wait->iomsg);
  gfc_free_expr (wait->id);
}


gfc_try
gfc_resolve_wait (gfc_wait *wait)
{
  RESOLVE_TAG (&tag_unit, wait->unit);
  RESOLVE_TAG (&tag_iomsg, wait->iomsg);
  RESOLVE_TAG (&tag_iostat, wait->iostat);
  RESOLVE_TAG (&tag_id, wait->id);

  if (gfc_reference_st_label (wait->err, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;
  
  if (gfc_reference_st_label (wait->end, ST_LABEL_TARGET) == FAILURE)
    return FAILURE;

  return SUCCESS;
}

/* Match an element of a WAIT statement.  */

#define RETM   if (m != MATCH_NO) return m;

static match
match_wait_element (gfc_wait *wait)
{
  match m;

  m = match_etag (&tag_unit, &wait->unit);
  RETM m = match_ltag (&tag_err, &wait->err);
  RETM m = match_ltag (&tag_end, &wait->eor);
  RETM m = match_ltag (&tag_eor, &wait->end);
  RETM m = match_out_tag (&tag_iomsg, &wait->iomsg);
  RETM m = match_out_tag (&tag_iostat, &wait->iostat);
  RETM m = match_etag (&tag_id, &wait->id);
  RETM return MATCH_NO;
}

#undef RETM


match
gfc_match_wait (void)
{
  gfc_wait *wait;
  match m;

  m = gfc_match_char ('(');
  if (m == MATCH_NO)
    return m;

  wait = XCNEW (gfc_wait);

  m = match_wait_element (wait);
  if (m == MATCH_ERROR)
    goto cleanup;
  if (m == MATCH_NO)
    {
      m = gfc_match_expr (&wait->unit);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  for (;;)
    {
      if (gfc_match_char (')') == MATCH_YES)
	break;
      if (gfc_match_char (',') != MATCH_YES)
	goto syntax;

      m = match_wait_element (wait);
      if (m == MATCH_ERROR)
	goto cleanup;
      if (m == MATCH_NO)
	goto syntax;
    }

  if (gfc_notify_std (GFC_STD_F2003, "Fortran 2003: WAIT at %C "
	  "not allowed in Fortran 95") == FAILURE)
    goto cleanup;

  if (gfc_pure (NULL))
    {
      gfc_error ("WAIT statement not allowed in PURE procedure at %C");
      goto cleanup;
    }

  if (gfc_implicit_pure (NULL))
    gfc_current_ns->proc_name->attr.implicit_pure = 0;

  new_st.op = EXEC_WAIT;
  new_st.ext.wait = wait;

  return MATCH_YES;

syntax:
  gfc_syntax_error (ST_WAIT);

cleanup:
  gfc_free_wait (wait);
  return MATCH_ERROR;
}