gcc/cppinit.c

   1 /* CPP Library.
   2    Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4    Contributed by Per Bothner, 1994-95.
   5    Based on CCCP program by Paul Rubin, June 1986
   6    Adapted to ANSI C, Richard Stallman, Jan 1987
   7
   8 This program is free software; you can redistribute it and/or modify it
   9 under the terms of the GNU General Public License as published by the
  10 Free Software Foundation; either version 2, or (at your option) any
  11 later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "cpplib.h"
  25 #include "cpphash.h"
  26 #include "mkdeps.h"
  27
  28 static void init_library (void);
  29 static void mark_named_operators (cpp_reader *);
  30 static void read_original_filename (cpp_reader *);
  31 static void read_original_directory (cpp_reader *);
  32 static void post_options (cpp_reader *);
  33
  34 /* If we have designated initializers (GCC >2.7) these tables can be
  35    initialized, constant data.  Otherwise, they have to be filled in at
  36    runtime.  */
  37 #if HAVE_DESIGNATED_INITIALIZERS
  38
  39 #define init_trigraph_map()  /* Nothing.  */
  40 #define TRIGRAPH_MAP \
  41 __extension__ const uchar _cpp_trigraph_map[UCHAR_MAX + 1] = {
  42
  43 #define END };
  44 #define s(p, v) [p] = v,
  45
  46 #else
  47
  48 #define TRIGRAPH_MAP uchar _cpp_trigraph_map[UCHAR_MAX + 1] = { 0 }; \
  49  static void init_trigraph_map (void) { \
  50  unsigned char *x = _cpp_trigraph_map;
  51
  52 #define END }
  53 #define s(p, v) x[p] = v;
  54
  55 #endif
  56
  57 TRIGRAPH_MAP
  58   s('=', '#')   s(')', ']')     s('!', '|')
  59   s('(', '[')   s('\'', '^')    s('>', '}')
  60   s('/', '\\')  s('<', '{')     s('-', '~')
  61 END
  62
  63 #undef s
  64 #undef END
  65 #undef TRIGRAPH_MAP
  66
  67 /* A set of booleans indicating what CPP features each source language
  68    requires.  */
  69 struct lang_flags
  70 {
  71   char c99;
  72   char cplusplus;
  73   char extended_numbers;
  74   char std;
  75   char cplusplus_comments;
  76   char digraphs;
  77 };
  78
  79 static const struct lang_flags lang_defaults[] =
  80 { /*              c99 c++ xnum std  //   digr  */
  81   /* GNUC89 */  { 0,  0,  1,   0,   1,   1     },
  82   /* GNUC99 */  { 1,  0,  1,   0,   1,   1     },
  83   /* STDC89 */  { 0,  0,  0,   1,   0,   0     },
  84   /* STDC94 */  { 0,  0,  0,   1,   0,   1     },
  85   /* STDC99 */  { 1,  0,  1,   1,   1,   1     },
  86   /* GNUCXX */  { 0,  1,  1,   0,   1,   1     },
  87   /* CXX98  */  { 0,  1,  1,   1,   1,   1     },
  88   /* ASM    */  { 0,  0,  1,   0,   1,   0     }
  89 };
  90
  91 /* Sets internal flags correctly for a given language.  */
  92 void
  93 cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
  94 {
  95   const struct lang_flags *l = &lang_defaults[(int) lang];
  96
  97   CPP_OPTION (pfile, lang) = lang;
  98
  99   CPP_OPTION (pfile, c99)                = l->c99;
 100   CPP_OPTION (pfile, cplusplus)          = l->cplusplus;
 101   CPP_OPTION (pfile, extended_numbers)   = l->extended_numbers;
 102   CPP_OPTION (pfile, std)                = l->std;
 103   CPP_OPTION (pfile, trigraphs)          = l->std;
 104   CPP_OPTION (pfile, cplusplus_comments) = l->cplusplus_comments;
 105   CPP_OPTION (pfile, digraphs)           = l->digraphs;
 106 }
 107
 108 /* Initialize library global state.  */
 109 static void
 110 init_library (void)
 111 {
 112   static int initialized = 0;
 113
 114   if (! initialized)
 115     {
 116       initialized = 1;
 117
 118       /* Set up the trigraph map.  This doesn't need to do anything if
 119          we were compiled with a compiler that supports C99 designated
 120          initializers.  */
 121       init_trigraph_map ();
 122     }
 123 }
 124
 125 /* Initialize a cpp_reader structure.  */
 126 cpp_reader *
 127 cpp_create_reader (enum c_lang lang, hash_table *table,
 128                    struct line_maps *line_table)
 129 {
 130   cpp_reader *pfile;
 131
 132   /* Initialize this instance of the library if it hasn't been already.  */
 133   init_library ();
 134
 135   pfile = xcalloc (1, sizeof (cpp_reader));
 136
 137   cpp_set_lang (pfile, lang);
 138   CPP_OPTION (pfile, warn_multichar) = 1;
 139   CPP_OPTION (pfile, discard_comments) = 1;
 140   CPP_OPTION (pfile, discard_comments_in_macro_exp) = 1;
 141   CPP_OPTION (pfile, show_column) = 1;
 142   CPP_OPTION (pfile, tabstop) = 8;
 143   CPP_OPTION (pfile, operator_names) = 1;
 144   CPP_OPTION (pfile, warn_trigraphs) = 2;
 145   CPP_OPTION (pfile, warn_endif_labels) = 1;
 146   CPP_OPTION (pfile, warn_deprecated) = 1;
 147   CPP_OPTION (pfile, warn_long_long) = !CPP_OPTION (pfile, c99);
 148   CPP_OPTION (pfile, dollars_in_ident) = 1;
 149   CPP_OPTION (pfile, warn_dollars) = 1;
 150   CPP_OPTION (pfile, warn_variadic_macros) = 1;
 151
 152   /* Default CPP arithmetic to something sensible for the host for the
 153      benefit of dumb users like fix-header.  */
 154   CPP_OPTION (pfile, precision) = CHAR_BIT * sizeof (long);
 155   CPP_OPTION (pfile, char_precision) = CHAR_BIT;
 156   CPP_OPTION (pfile, wchar_precision) = CHAR_BIT * sizeof (int);
 157   CPP_OPTION (pfile, int_precision) = CHAR_BIT * sizeof (int);
 158   CPP_OPTION (pfile, unsigned_char) = 0;
 159   CPP_OPTION (pfile, unsigned_wchar) = 1;
 160   CPP_OPTION (pfile, bytes_big_endian) = 1;  /* does not matter */
 161
 162   /* Default to no charset conversion.  */
 163   CPP_OPTION (pfile, narrow_charset) = _cpp_default_encoding ();
 164   CPP_OPTION (pfile, wide_charset) = 0;
 165
 166   /* Default the input character set to UTF-8.  */
 167   CPP_OPTION (pfile, input_charset) = _cpp_default_encoding ();
 168
 169   /* A fake empty "directory" used as the starting point for files
 170      looked up without a search path.  Name cannot be '/' because we
 171      don't want to prepend anything at all to filenames using it.  All
 172      other entries are correct zero-initialized.  */
 173   pfile->no_search_path.name = (char *) "";
 174
 175   /* Initialize the line map.  */
 176   pfile->line_table = line_table;
 177
 178   /* Initialize lexer state.  */
 179   pfile->state.save_comments = ! CPP_OPTION (pfile, discard_comments);
 180
 181   /* Set up static tokens.  */
 182   pfile->avoid_paste.type = CPP_PADDING;
 183   pfile->avoid_paste.val.source = NULL;
 184   pfile->eof.type = CPP_EOF;
 185   pfile->eof.flags = 0;
 186
 187   /* Create a token buffer for the lexer.  */
 188   _cpp_init_tokenrun (&pfile->base_run, 250);
 189   pfile->cur_run = &pfile->base_run;
 190   pfile->cur_token = pfile->base_run.base;
 191
 192   /* Initialize the base context.  */
 193   pfile->context = &pfile->base_context;
 194   pfile->base_context.macro = 0;
 195   pfile->base_context.prev = pfile->base_context.next = 0;
 196
 197   /* Aligned and unaligned storage.  */
 198   pfile->a_buff = _cpp_get_buff (pfile, 0);
 199   pfile->u_buff = _cpp_get_buff (pfile, 0);
 200
 201   /* The expression parser stack.  */
 202   _cpp_expand_op_stack (pfile);
 203
 204   /* Initialize the buffer obstack.  */
 205   _obstack_begin (&pfile->buffer_ob, 0, 0,
 206                   (void *(*) (long)) xmalloc,
 207                   (void (*) (void *)) free);
 208
 209   _cpp_init_files (pfile);
 210
 211   _cpp_init_hashtable (pfile, table);
 212
 213   return pfile;
 214 }
 215
 216 /* Free resources used by PFILE.  Accessing PFILE after this function
 217    returns leads to undefined behavior.  Returns the error count.  */
 218 void
 219 cpp_destroy (cpp_reader *pfile)
 220 {
 221   cpp_context *context, *contextn;
 222   tokenrun *run, *runn;
 223
 224   free (pfile->op_stack);
 225
 226   while (CPP_BUFFER (pfile) != NULL)
 227     _cpp_pop_buffer (pfile);
 228
 229   if (pfile->out.base)
 230     free (pfile->out.base);
 231
 232   if (pfile->macro_buffer)
 233     {
 234       free (pfile->macro_buffer);
 235       pfile->macro_buffer = NULL;
 236       pfile->macro_buffer_len = 0;
 237     }
 238
 239   if (pfile->deps)
 240     deps_free (pfile->deps);
 241   obstack_free (&pfile->buffer_ob, 0);
 242
 243   _cpp_destroy_hashtable (pfile);
 244   _cpp_cleanup_files (pfile);
 245   _cpp_destroy_iconv (pfile);
 246
 247   _cpp_free_buff (pfile->a_buff);
 248   _cpp_free_buff (pfile->u_buff);
 249   _cpp_free_buff (pfile->free_buffs);
 250
 251   for (run = &pfile->base_run; run; run = runn)
 252     {
 253       runn = run->next;
 254       free (run->base);
 255       if (run != &pfile->base_run)
 256         free (run);
 257     }
 258
 259   for (context = pfile->base_context.next; context; context = contextn)
 260     {
 261       contextn = context->next;
 262       free (context);
 263     }
 264
 265   free (pfile);
 266 }
 267
 268 /* This structure defines one built-in identifier.  A node will be
 269    entered in the hash table under the name NAME, with value VALUE.
 270
 271    There are two tables of these.  builtin_array holds all the
 272    "builtin" macros: these are handled by builtin_macro() in
 273    cppmacro.c.  Builtin is somewhat of a misnomer -- the property of
 274    interest is that these macros require special code to compute their
 275    expansions.  The value is a "builtin_type" enumerator.
 276
 277    operator_array holds the C++ named operators.  These are keywords
 278    which act as aliases for punctuators.  In C++, they cannot be
 279    altered through #define, and #if recognizes them as operators.  In
 280    C, these are not entered into the hash table at all (but see
 281    <iso646.h>).  The value is a token-type enumerator.  */
 282 struct builtin
 283 {
 284   const uchar *name;
 285   unsigned short len;
 286   unsigned short value;
 287 };
 288
 289 #define B(n, t)    { DSC(n), t }
 290 static const struct builtin builtin_array[] =
 291 {
 292   B("__TIME__",          BT_TIME),
 293   B("__DATE__",          BT_DATE),
 294   B("__FILE__",          BT_FILE),
 295   B("__BASE_FILE__",     BT_BASE_FILE),
 296   B("__LINE__",          BT_SPECLINE),
 297   B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL),
 298   /* Keep builtins not used for -traditional-cpp at the end, and
 299      update init_builtins() if any more are added.  */
 300   B("_Pragma",           BT_PRAGMA),
 301   B("__STDC__",          BT_STDC),
 302 };
 303
 304 static const struct builtin operator_array[] =
 305 {
 306   B("and",      CPP_AND_AND),
 307   B("and_eq",   CPP_AND_EQ),
 308   B("bitand",   CPP_AND),
 309   B("bitor",    CPP_OR),
 310   B("compl",    CPP_COMPL),
 311   B("not",      CPP_NOT),
 312   B("not_eq",   CPP_NOT_EQ),
 313   B("or",       CPP_OR_OR),
 314   B("or_eq",    CPP_OR_EQ),
 315   B("xor",      CPP_XOR),
 316   B("xor_eq",   CPP_XOR_EQ)
 317 };
 318 #undef B
 319
 320 /* Mark the C++ named operators in the hash table.  */
 321 static void
 322 mark_named_operators (cpp_reader *pfile)
 323 {
 324   const struct builtin *b;
 325
 326   for (b = operator_array;
 327        b < (operator_array + ARRAY_SIZE (operator_array));
 328        b++)
 329     {
 330       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 331       hp->flags |= NODE_OPERATOR;
 332       hp->is_directive = 0;
 333       hp->directive_index = b->value;
 334     }
 335 }
 336
 337 /* Read the builtins table above and enter them, and language-specific
 338    macros, into the hash table.  HOSTED is true if this is a hosted
 339    environment.  */
 340 void
 341 cpp_init_builtins (cpp_reader *pfile, int hosted)
 342 {
 343   const struct builtin *b;
 344   size_t n = ARRAY_SIZE (builtin_array);
 345
 346   if (CPP_OPTION (pfile, traditional))
 347     n -= 2;
 348
 349   for(b = builtin_array; b < builtin_array + n; b++)
 350     {
 351       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 352       hp->type = NT_MACRO;
 353       hp->flags |= NODE_BUILTIN | NODE_WARN;
 354       hp->value.builtin = b->value;
 355     }
 356
 357   if (CPP_OPTION (pfile, cplusplus))
 358     _cpp_define_builtin (pfile, "__cplusplus 1");
 359   else if (CPP_OPTION (pfile, lang) == CLK_ASM)
 360     _cpp_define_builtin (pfile, "__ASSEMBLER__ 1");
 361   else if (CPP_OPTION (pfile, lang) == CLK_STDC94)
 362     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199409L");
 363   else if (CPP_OPTION (pfile, c99))
 364     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199901L");
 365
 366   if (hosted)
 367     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 1");
 368   else
 369     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 0");
 370
 371   if (CPP_OPTION (pfile, objc))
 372     _cpp_define_builtin (pfile, "__OBJC__ 1");
 373 }
 374
 375 /* Sanity-checks are dependent on command-line options, so it is
 376    called as a subroutine of cpp_read_main_file ().  */
 377 #if ENABLE_CHECKING
 378 static void sanity_checks (cpp_reader *);
 379 static void sanity_checks (cpp_reader *pfile)
 380 {
 381   cppchar_t test = 0;
 382   size_t max_precision = 2 * CHAR_BIT * sizeof (cpp_num_part);
 383
 384   /* Sanity checks for assumptions about CPP arithmetic and target
 385      type precisions made by cpplib.  */
 386   test--;
 387   if (test < 1)
 388     cpp_error (pfile, CPP_DL_ICE, "cppchar_t must be an unsigned type");
 389
 390   if (CPP_OPTION (pfile, precision) > max_precision)
 391     cpp_error (pfile, CPP_DL_ICE,
 392                "preprocessor arithmetic has maximum precision of %lu bits;"
 393                " target requires %lu bits",
 394                (unsigned long) max_precision,
 395                (unsigned long) CPP_OPTION (pfile, precision));
 396
 397   if (CPP_OPTION (pfile, precision) < CPP_OPTION (pfile, int_precision))
 398     cpp_error (pfile, CPP_DL_ICE,
 399                "CPP arithmetic must be at least as precise as a target int");
 400
 401   if (CPP_OPTION (pfile, char_precision) < 8)
 402     cpp_error (pfile, CPP_DL_ICE, "target char is less than 8 bits wide");
 403
 404   if (CPP_OPTION (pfile, wchar_precision) < CPP_OPTION (pfile, char_precision))
 405     cpp_error (pfile, CPP_DL_ICE,
 406                "target wchar_t is narrower than target char");
 407
 408   if (CPP_OPTION (pfile, int_precision) < CPP_OPTION (pfile, char_precision))
 409     cpp_error (pfile, CPP_DL_ICE,
 410                "target int is narrower than target char");
 411
 412   /* This is assumed in eval_token() and could be fixed if necessary.  */
 413   if (sizeof (cppchar_t) > sizeof (cpp_num_part))
 414     cpp_error (pfile, CPP_DL_ICE,
 415                "CPP half-integer narrower than CPP character");
 416
 417   if (CPP_OPTION (pfile, wchar_precision) > BITS_PER_CPPCHAR_T)
 418     cpp_error (pfile, CPP_DL_ICE,
 419                "CPP on this host cannot handle wide character constants over"
 420                " %lu bits, but the target requires %lu bits",
 421                (unsigned long) BITS_PER_CPPCHAR_T,
 422                (unsigned long) CPP_OPTION (pfile, wchar_precision));
 423 }
 424 #else
 425 # define sanity_checks(PFILE)
 426 #endif
 427
 428 /* Add a dependency target.  Can be called any number of times before
 429    cpp_read_main_file().  If no targets have been added before
 430    cpp_read_main_file(), then the default target is used.  */
 431 void
 432 cpp_add_dependency_target (cpp_reader *pfile, const char *target, int quote)
 433 {
 434   if (!pfile->deps)
 435     pfile->deps = deps_init ();
 436
 437   deps_add_target (pfile->deps, target, quote);
 438 }
 439
 440 /* This is called after options have been parsed, and partially
 441    processed.  */
 442 void
 443 cpp_post_options (cpp_reader *pfile)
 444 {
 445   sanity_checks (pfile);
 446
 447   post_options (pfile);
 448
 449   /* Mark named operators before handling command line macros.  */
 450   if (CPP_OPTION (pfile, cplusplus) && CPP_OPTION (pfile, operator_names))
 451     mark_named_operators (pfile);
 452 }
 453
 454 /* Setup for processing input from the file named FNAME, or stdin if
 455    it is the empty string.  Return the original filename
 456    on success (e.g. foo.i->foo.c), or NULL on failure.  */
 457 const char *
 458 cpp_read_main_file (cpp_reader *pfile, const char *fname)
 459 {
 460   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE)
 461     {
 462       if (!pfile->deps)
 463         pfile->deps = deps_init ();
 464
 465       /* Set the default target (if there is none already).  */
 466       deps_add_default_target (pfile->deps, fname);
 467     }
 468
 469   pfile->main_file
 470     = _cpp_find_file (pfile, fname, &pfile->no_search_path, false);
 471   if (_cpp_find_failed (pfile->main_file))
 472     return NULL;
 473
 474   _cpp_stack_file (pfile, pfile->main_file, false);
 475
 476   /* For foo.i, read the original filename foo.c now, for the benefit
 477      of the front ends.  */
 478   if (CPP_OPTION (pfile, preprocessed))
 479     {
 480       read_original_filename (pfile);
 481       fname = pfile->line_table->maps[pfile->line_table->used-1].to_file;
 482     }
 483   return fname;
 484 }
 485
 486 /* For preprocessed files, if the first tokens are of the form # NUM.
 487    handle the directive so we know the original file name.  This will
 488    generate file_change callbacks, which the front ends must handle
 489    appropriately given their state of initialization.  */
 490 static void
 491 read_original_filename (cpp_reader *pfile)
 492 {
 493   const cpp_token *token, *token1;
 494
 495   /* Lex ahead; if the first tokens are of the form # NUM, then
 496      process the directive, otherwise back up.  */
 497   token = _cpp_lex_direct (pfile);
 498   if (token->type == CPP_HASH)
 499     {
 500       token1 = _cpp_lex_direct (pfile);
 501       _cpp_backup_tokens (pfile, 1);
 502
 503       /* If it's a #line directive, handle it.  */
 504       if (token1->type == CPP_NUMBER)
 505         {
 506           _cpp_handle_directive (pfile, token->flags & PREV_WHITE);
 507           read_original_directory (pfile);
 508           return;
 509         }
 510     }
 511
 512   /* Backup as if nothing happened.  */
 513   _cpp_backup_tokens (pfile, 1);
 514 }
 515
 516 /* For preprocessed files, if the tokens following the first filename
 517    line is of the form # <line> "/path/name//", handle the
 518    directive so we know the original current directory.  */
 519 static void
 520 read_original_directory (cpp_reader *pfile)
 521 {
 522   const cpp_token *hash, *token;
 523
 524   /* Lex ahead; if the first tokens are of the form # NUM, then
 525      process the directive, otherwise back up.  */
 526   hash = _cpp_lex_direct (pfile);
 527   if (hash->type != CPP_HASH)
 528     {
 529       _cpp_backup_tokens (pfile, 1);
 530       return;
 531     }
 532
 533   token = _cpp_lex_direct (pfile);
 534
 535   if (token->type != CPP_NUMBER)
 536     {
 537       _cpp_backup_tokens (pfile, 2);
 538       return;
 539     }
 540
 541   token = _cpp_lex_direct (pfile);
 542
 543   if (token->type != CPP_STRING
 544       || ! (token->val.str.len >= 5
 545             && token->val.str.text[token->val.str.len-2] == '/'
 546             && token->val.str.text[token->val.str.len-3] == '/'))
 547     {
 548       _cpp_backup_tokens (pfile, 3);
 549       return;
 550     }
 551
 552   if (pfile->cb.dir_change)
 553     {
 554       char *debugdir = alloca (token->val.str.len - 3);
 555
 556       memcpy (debugdir, (const char *) token->val.str.text + 1,
 557               token->val.str.len - 4);
 558       debugdir[token->val.str.len - 4] = '\0';
 559
 560       pfile->cb.dir_change (pfile, debugdir);
 561     }
 562 }
 563
 564 /* This is called at the end of preprocessing.  It pops the last
 565    buffer and writes dependency output, and returns the number of
 566    errors.
 567
 568    Maybe it should also reset state, such that you could call
 569    cpp_start_read with a new filename to restart processing.  */
 570 int
 571 cpp_finish (cpp_reader *pfile, FILE *deps_stream)
 572 {
 573   /* Warn about unused macros before popping the final buffer.  */
 574   if (CPP_OPTION (pfile, warn_unused_macros))
 575     cpp_forall_identifiers (pfile, _cpp_warn_if_unused_macro, NULL);
 576
 577   /* cpplex.c leaves the final buffer on the stack.  This it so that
 578      it returns an unending stream of CPP_EOFs to the client.  If we
 579      popped the buffer, we'd dereference a NULL buffer pointer and
 580      segfault.  It's nice to allow the client to do worry-free excess
 581      cpp_get_token calls.  */
 582   while (pfile->buffer)
 583     _cpp_pop_buffer (pfile);
 584
 585   /* Don't write the deps file if there are errors.  */
 586   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE
 587       && deps_stream && pfile->errors == 0)
 588     {
 589       deps_write (pfile->deps, deps_stream, 72);
 590
 591       if (CPP_OPTION (pfile, deps.phony_targets))
 592         deps_phony_targets (pfile->deps, deps_stream);
 593     }
 594
 595   /* Report on headers that could use multiple include guards.  */
 596   if (CPP_OPTION (pfile, print_include_names))
 597     _cpp_report_missing_guards (pfile);
 598
 599   return pfile->errors;
 600 }
 601
 602 static void
 603 post_options (cpp_reader *pfile)
 604 {
 605   /* -Wtraditional is not useful in C++ mode.  */
 606   if (CPP_OPTION (pfile, cplusplus))
 607     CPP_OPTION (pfile, warn_traditional) = 0;
 608
 609   /* Permanently disable macro expansion if we are rescanning
 610      preprocessed text.  Read preprocesed source in ISO mode.  */
 611   if (CPP_OPTION (pfile, preprocessed))
 612     {
 613       pfile->state.prevent_expansion = 1;
 614       CPP_OPTION (pfile, traditional) = 0;
 615     }
 616
 617   if (CPP_OPTION (pfile, warn_trigraphs) == 2)
 618     CPP_OPTION (pfile, warn_trigraphs) = !CPP_OPTION (pfile, trigraphs);
 619
 620   if (CPP_OPTION (pfile, traditional))
 621     {
 622       /* Traditional CPP does not accurately track column information.  */
 623       CPP_OPTION (pfile, show_column) = 0;
 624       CPP_OPTION (pfile, trigraphs) = 0;
 625       CPP_OPTION (pfile, warn_trigraphs) = 0;
 626     }
 627 }