libcpp/init.c

   1 /* CPP Library.
   2    Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "cpplib.h"
  25 #include "internal.h"
  26 #include "mkdeps.h"
  27 #include "localedir.h"
  28
  29 static void init_library (void);
  30 static void mark_named_operators (cpp_reader *);
  31 static void read_original_filename (cpp_reader *);
  32 static void read_original_directory (cpp_reader *);
  33 static void post_options (cpp_reader *);
  34
  35 /* If we have designated initializers (GCC >2.7) these tables can be
  36    initialized, constant data.  Otherwise, they have to be filled in at
  37    runtime.  */
  38 #if HAVE_DESIGNATED_INITIALIZERS
  39
  40 #define init_trigraph_map()  /* Nothing.  */
  41 #define TRIGRAPH_MAP \
  42 __extension__ const uchar _cpp_trigraph_map[UCHAR_MAX + 1] = {
  43
  44 #define END };
  45 #define s(p, v) [p] = v,
  46
  47 #else
  48
  49 #define TRIGRAPH_MAP uchar _cpp_trigraph_map[UCHAR_MAX + 1] = { 0 }; \
  50  static void init_trigraph_map (void) { \
  51  unsigned char *x = _cpp_trigraph_map;
  52
  53 #define END }
  54 #define s(p, v) x[p] = v;
  55
  56 #endif
  57
  58 TRIGRAPH_MAP
  59   s('=', '#')   s(')', ']')     s('!', '|')
  60   s('(', '[')   s('\'', '^')    s('>', '}')
  61   s('/', '\\')  s('<', '{')     s('-', '~')
  62 END
  63
  64 #undef s
  65 #undef END
  66 #undef TRIGRAPH_MAP
  67
  68 /* A set of booleans indicating what CPP features each source language
  69    requires.  */
  70 struct lang_flags
  71 {
  72   char c99;
  73   char cplusplus;
  74   char extended_numbers;
  75   char extended_identifiers;
  76   char std;
  77   char cplusplus_comments;
  78   char digraphs;
  79   char uliterals;
  80 };
  81
  82 static const struct lang_flags lang_defaults[] =
  83 { /*              c99 c++ xnum xid std  //   digr ulit */
  84   /* GNUC89   */  { 0,  0,  1,   0,  0,   1,   1,   0 },
  85   /* GNUC99   */  { 1,  0,  1,   0,  0,   1,   1,   1 },
  86   /* STDC89   */  { 0,  0,  0,   0,  1,   0,   0,   0 },
  87   /* STDC94   */  { 0,  0,  0,   0,  1,   0,   1,   0 },
  88   /* STDC99   */  { 1,  0,  1,   0,  1,   1,   1,   0 },
  89   /* GNUCXX   */  { 0,  1,  1,   0,  0,   1,   1,   0 },
  90   /* CXX98    */  { 0,  1,  1,   0,  1,   1,   1,   0 },
  91   /* GNUCXX0X */  { 1,  1,  1,   0,  0,   1,   1,   1 },
  92   /* CXX0X    */  { 1,  1,  1,   0,  1,   1,   1,   1 },
  93   /* ASM      */  { 0,  0,  1,   0,  0,   1,   0,   0 }
  94   /* xid should be 1 for GNUC99, STDC99, GNUCXX, CXX98, GNUCXX0X, and
  95      CXX0X when no longer experimental (when all uses of identifiers
  96      in the compiler have been audited for correct handling of
  97      extended identifiers).  */
  98 };
  99
 100 /* Sets internal flags correctly for a given language.  */
 101 void
 102 cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
 103 {
 104   const struct lang_flags *l = &lang_defaults[(int) lang];
 105
 106   CPP_OPTION (pfile, lang) = lang;
 107
 108   CPP_OPTION (pfile, c99)                        = l->c99;
 109   CPP_OPTION (pfile, cplusplus)                  = l->cplusplus;
 110   CPP_OPTION (pfile, extended_numbers)           = l->extended_numbers;
 111   CPP_OPTION (pfile, extended_identifiers)       = l->extended_identifiers;
 112   CPP_OPTION (pfile, std)                        = l->std;
 113   CPP_OPTION (pfile, trigraphs)                  = l->std;
 114   CPP_OPTION (pfile, cplusplus_comments)         = l->cplusplus_comments;
 115   CPP_OPTION (pfile, digraphs)                   = l->digraphs;
 116   CPP_OPTION (pfile, uliterals)                  = l->uliterals;
 117 }
 118
 119 /* Initialize library global state.  */
 120 static void
 121 init_library (void)
 122 {
 123   static int initialized = 0;
 124
 125   if (! initialized)
 126     {
 127       initialized = 1;
 128
 129       /* Set up the trigraph map.  This doesn't need to do anything if
 130          we were compiled with a compiler that supports C99 designated
 131          initializers.  */
 132       init_trigraph_map ();
 133
 134 #ifdef ENABLE_NLS
 135        (void) bindtextdomain (PACKAGE, LOCALEDIR);
 136 #endif
 137     }
 138 }
 139
 140 /* Initialize a cpp_reader structure.  */
 141 cpp_reader *
 142 cpp_create_reader (enum c_lang lang, hash_table *table,
 143                    struct line_maps *line_table)
 144 {
 145   cpp_reader *pfile;
 146
 147   /* Initialize this instance of the library if it hasn't been already.  */
 148   init_library ();
 149
 150   pfile = XCNEW (cpp_reader);
 151
 152   cpp_set_lang (pfile, lang);
 153   CPP_OPTION (pfile, warn_multichar) = 1;
 154   CPP_OPTION (pfile, discard_comments) = 1;
 155   CPP_OPTION (pfile, discard_comments_in_macro_exp) = 1;
 156   CPP_OPTION (pfile, show_column) = 1;
 157   CPP_OPTION (pfile, tabstop) = 8;
 158   CPP_OPTION (pfile, operator_names) = 1;
 159   CPP_OPTION (pfile, warn_trigraphs) = 2;
 160   CPP_OPTION (pfile, warn_endif_labels) = 1;
 161   CPP_OPTION (pfile, warn_deprecated) = 1;
 162   CPP_OPTION (pfile, warn_long_long) = !CPP_OPTION (pfile, c99);
 163   CPP_OPTION (pfile, dollars_in_ident) = 1;
 164   CPP_OPTION (pfile, warn_dollars) = 1;
 165   CPP_OPTION (pfile, warn_variadic_macros) = 1;
 166   CPP_OPTION (pfile, warn_normalize) = normalized_C;
 167
 168   /* Default CPP arithmetic to something sensible for the host for the
 169      benefit of dumb users like fix-header.  */
 170   CPP_OPTION (pfile, precision) = CHAR_BIT * sizeof (long);
 171   CPP_OPTION (pfile, char_precision) = CHAR_BIT;
 172   CPP_OPTION (pfile, wchar_precision) = CHAR_BIT * sizeof (int);
 173   CPP_OPTION (pfile, int_precision) = CHAR_BIT * sizeof (int);
 174   CPP_OPTION (pfile, unsigned_char) = 0;
 175   CPP_OPTION (pfile, unsigned_wchar) = 1;
 176   CPP_OPTION (pfile, bytes_big_endian) = 1;  /* does not matter */
 177
 178   /* Default to no charset conversion.  */
 179   CPP_OPTION (pfile, narrow_charset) = _cpp_default_encoding ();
 180   CPP_OPTION (pfile, wide_charset) = 0;
 181
 182   /* Default the input character set to UTF-8.  */
 183   CPP_OPTION (pfile, input_charset) = _cpp_default_encoding ();
 184
 185   /* A fake empty "directory" used as the starting point for files
 186      looked up without a search path.  Name cannot be '/' because we
 187      don't want to prepend anything at all to filenames using it.  All
 188      other entries are correct zero-initialized.  */
 189   pfile->no_search_path.name = (char *) "";
 190
 191   /* Initialize the line map.  */
 192   pfile->line_table = line_table;
 193
 194   /* Initialize lexer state.  */
 195   pfile->state.save_comments = ! CPP_OPTION (pfile, discard_comments);
 196
 197   /* Set up static tokens.  */
 198   pfile->avoid_paste.type = CPP_PADDING;
 199   pfile->avoid_paste.val.source = NULL;
 200   pfile->eof.type = CPP_EOF;
 201   pfile->eof.flags = 0;
 202
 203   /* Create a token buffer for the lexer.  */
 204   _cpp_init_tokenrun (&pfile->base_run, 250);
 205   pfile->cur_run = &pfile->base_run;
 206   pfile->cur_token = pfile->base_run.base;
 207
 208   /* Initialize the base context.  */
 209   pfile->context = &pfile->base_context;
 210   pfile->base_context.macro = 0;
 211   pfile->base_context.prev = pfile->base_context.next = 0;
 212
 213   /* Aligned and unaligned storage.  */
 214   pfile->a_buff = _cpp_get_buff (pfile, 0);
 215   pfile->u_buff = _cpp_get_buff (pfile, 0);
 216
 217   /* The expression parser stack.  */
 218   _cpp_expand_op_stack (pfile);
 219
 220   /* Initialize the buffer obstack.  */
 221   _obstack_begin (&pfile->buffer_ob, 0, 0,
 222                   (void *(*) (long)) xmalloc,
 223                   (void (*) (void *)) free);
 224
 225   _cpp_init_files (pfile);
 226
 227   _cpp_init_hashtable (pfile, table);
 228
 229   return pfile;
 230 }
 231
 232 /* Set the line_table entry in PFILE.  This is called after reading a
 233    PCH file, as the old line_table will be incorrect.  */
 234 void
 235 cpp_set_line_map (cpp_reader *pfile, struct line_maps *line_table)
 236 {
 237   pfile->line_table = line_table;
 238 }
 239
 240 /* Free resources used by PFILE.  Accessing PFILE after this function
 241    returns leads to undefined behavior.  Returns the error count.  */
 242 void
 243 cpp_destroy (cpp_reader *pfile)
 244 {
 245   cpp_context *context, *contextn;
 246   tokenrun *run, *runn;
 247
 248   free (pfile->op_stack);
 249
 250   while (CPP_BUFFER (pfile) != NULL)
 251     _cpp_pop_buffer (pfile);
 252
 253   if (pfile->out.base)
 254     free (pfile->out.base);
 255
 256   if (pfile->macro_buffer)
 257     {
 258       free (pfile->macro_buffer);
 259       pfile->macro_buffer = NULL;
 260       pfile->macro_buffer_len = 0;
 261     }
 262
 263   if (pfile->deps)
 264     deps_free (pfile->deps);
 265   obstack_free (&pfile->buffer_ob, 0);
 266
 267   _cpp_destroy_hashtable (pfile);
 268   _cpp_cleanup_files (pfile);
 269   _cpp_destroy_iconv (pfile);
 270
 271   _cpp_free_buff (pfile->a_buff);
 272   _cpp_free_buff (pfile->u_buff);
 273   _cpp_free_buff (pfile->free_buffs);
 274
 275   for (run = &pfile->base_run; run; run = runn)
 276     {
 277       runn = run->next;
 278       free (run->base);
 279       if (run != &pfile->base_run)
 280         free (run);
 281     }
 282
 283   for (context = pfile->base_context.next; context; context = contextn)
 284     {
 285       contextn = context->next;
 286       free (context);
 287     }
 288
 289   free (pfile);
 290 }
 291
 292 /* This structure defines one built-in identifier.  A node will be
 293    entered in the hash table under the name NAME, with value VALUE.
 294
 295    There are two tables of these.  builtin_array holds all the
 296    "builtin" macros: these are handled by builtin_macro() in
 297    macro.c.  Builtin is somewhat of a misnomer -- the property of
 298    interest is that these macros require special code to compute their
 299    expansions.  The value is a "builtin_type" enumerator.
 300
 301    operator_array holds the C++ named operators.  These are keywords
 302    which act as aliases for punctuators.  In C++, they cannot be
 303    altered through #define, and #if recognizes them as operators.  In
 304    C, these are not entered into the hash table at all (but see
 305    <iso646.h>).  The value is a token-type enumerator.  */
 306 struct builtin
 307 {
 308   const uchar *name;
 309   unsigned short len;
 310   unsigned short value;
 311 };
 312
 313 #define B(n, t)    { DSC(n), t }
 314 static const struct builtin builtin_array[] =
 315 {
 316   B("__TIMESTAMP__",     BT_TIMESTAMP),
 317   B("__TIME__",          BT_TIME),
 318   B("__DATE__",          BT_DATE),
 319   B("__FILE__",          BT_FILE),
 320   B("__BASE_FILE__",     BT_BASE_FILE),
 321   B("__LINE__",          BT_SPECLINE),
 322   B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL),
 323   B("__COUNTER__",       BT_COUNTER),
 324   /* Keep builtins not used for -traditional-cpp at the end, and
 325      update init_builtins() if any more are added.  */
 326   B("_Pragma",           BT_PRAGMA),
 327   B("__STDC__",          BT_STDC),
 328 };
 329
 330 static const struct builtin operator_array[] =
 331 {
 332   B("and",      CPP_AND_AND),
 333   B("and_eq",   CPP_AND_EQ),
 334   B("bitand",   CPP_AND),
 335   B("bitor",    CPP_OR),
 336   B("compl",    CPP_COMPL),
 337   B("not",      CPP_NOT),
 338   B("not_eq",   CPP_NOT_EQ),
 339   B("or",       CPP_OR_OR),
 340   B("or_eq",    CPP_OR_EQ),
 341   B("xor",      CPP_XOR),
 342   B("xor_eq",   CPP_XOR_EQ)
 343 };
 344 #undef B
 345
 346 /* Mark the C++ named operators in the hash table.  */
 347 static void
 348 mark_named_operators (cpp_reader *pfile)
 349 {
 350   const struct builtin *b;
 351
 352   for (b = operator_array;
 353        b < (operator_array + ARRAY_SIZE (operator_array));
 354        b++)
 355     {
 356       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 357       hp->flags |= NODE_OPERATOR;
 358       hp->is_directive = 0;
 359       hp->directive_index = b->value;
 360     }
 361 }
 362
 363 void
 364 cpp_init_special_builtins (cpp_reader *pfile)
 365 {
 366   const struct builtin *b;
 367   size_t n = ARRAY_SIZE (builtin_array);
 368
 369   if (CPP_OPTION (pfile, traditional))
 370     n -= 2;
 371   else if (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 372            || CPP_OPTION (pfile, std))
 373     n--;
 374
 375   for (b = builtin_array; b < builtin_array + n; b++)
 376     {
 377       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 378       hp->type = NT_MACRO;
 379       hp->flags |= NODE_BUILTIN | NODE_WARN;
 380       hp->value.builtin = (enum builtin_type) b->value;
 381     }
 382 }
 383
 384 /* Read the builtins table above and enter them, and language-specific
 385    macros, into the hash table.  HOSTED is true if this is a hosted
 386    environment.  */
 387 void
 388 cpp_init_builtins (cpp_reader *pfile, int hosted)
 389 {
 390   cpp_init_special_builtins (pfile);
 391
 392   if (!CPP_OPTION (pfile, traditional)
 393       && (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 394           || CPP_OPTION (pfile, std)))
 395     _cpp_define_builtin (pfile, "__STDC__ 1");
 396
 397   if (CPP_OPTION (pfile, cplusplus))
 398     _cpp_define_builtin (pfile, "__cplusplus 1");
 399   else if (CPP_OPTION (pfile, lang) == CLK_ASM)
 400     _cpp_define_builtin (pfile, "__ASSEMBLER__ 1");
 401   else if (CPP_OPTION (pfile, lang) == CLK_STDC94)
 402     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199409L");
 403   else if (CPP_OPTION (pfile, c99))
 404     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199901L");
 405
 406   if (hosted)
 407     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 1");
 408   else
 409     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 0");
 410
 411   if (CPP_OPTION (pfile, objc))
 412     _cpp_define_builtin (pfile, "__OBJC__ 1");
 413 }
 414
 415 /* Sanity-checks are dependent on command-line options, so it is
 416    called as a subroutine of cpp_read_main_file ().  */
 417 #if ENABLE_CHECKING
 418 static void sanity_checks (cpp_reader *);
 419 static void sanity_checks (cpp_reader *pfile)
 420 {
 421   cppchar_t test = 0;
 422   size_t max_precision = 2 * CHAR_BIT * sizeof (cpp_num_part);
 423
 424   /* Sanity checks for assumptions about CPP arithmetic and target
 425      type precisions made by cpplib.  */
 426   test--;
 427   if (test < 1)
 428     cpp_error (pfile, CPP_DL_ICE, "cppchar_t must be an unsigned type");
 429
 430   if (CPP_OPTION (pfile, precision) > max_precision)
 431     cpp_error (pfile, CPP_DL_ICE,
 432                "preprocessor arithmetic has maximum precision of %lu bits;"
 433                " target requires %lu bits",
 434                (unsigned long) max_precision,
 435                (unsigned long) CPP_OPTION (pfile, precision));
 436
 437   if (CPP_OPTION (pfile, precision) < CPP_OPTION (pfile, int_precision))
 438     cpp_error (pfile, CPP_DL_ICE,
 439                "CPP arithmetic must be at least as precise as a target int");
 440
 441   if (CPP_OPTION (pfile, char_precision) < 8)
 442     cpp_error (pfile, CPP_DL_ICE, "target char is less than 8 bits wide");
 443
 444   if (CPP_OPTION (pfile, wchar_precision) < CPP_OPTION (pfile, char_precision))
 445     cpp_error (pfile, CPP_DL_ICE,
 446                "target wchar_t is narrower than target char");
 447
 448   if (CPP_OPTION (pfile, int_precision) < CPP_OPTION (pfile, char_precision))
 449     cpp_error (pfile, CPP_DL_ICE,
 450                "target int is narrower than target char");
 451
 452   /* This is assumed in eval_token() and could be fixed if necessary.  */
 453   if (sizeof (cppchar_t) > sizeof (cpp_num_part))
 454     cpp_error (pfile, CPP_DL_ICE,
 455                "CPP half-integer narrower than CPP character");
 456
 457   if (CPP_OPTION (pfile, wchar_precision) > BITS_PER_CPPCHAR_T)
 458     cpp_error (pfile, CPP_DL_ICE,
 459                "CPP on this host cannot handle wide character constants over"
 460                " %lu bits, but the target requires %lu bits",
 461                (unsigned long) BITS_PER_CPPCHAR_T,
 462                (unsigned long) CPP_OPTION (pfile, wchar_precision));
 463 }
 464 #else
 465 # define sanity_checks(PFILE)
 466 #endif
 467
 468 /* This is called after options have been parsed, and partially
 469    processed.  */
 470 void
 471 cpp_post_options (cpp_reader *pfile)
 472 {
 473   sanity_checks (pfile);
 474
 475   post_options (pfile);
 476
 477   /* Mark named operators before handling command line macros.  */
 478   if (CPP_OPTION (pfile, cplusplus) && CPP_OPTION (pfile, operator_names))
 479     mark_named_operators (pfile);
 480 }
 481
 482 /* Setup for processing input from the file named FNAME, or stdin if
 483    it is the empty string.  Return the original filename
 484    on success (e.g. foo.i->foo.c), or NULL on failure.  */
 485 const char *
 486 cpp_read_main_file (cpp_reader *pfile, const char *fname)
 487 {
 488   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE)
 489     {
 490       if (!pfile->deps)
 491         pfile->deps = deps_init ();
 492
 493       /* Set the default target (if there is none already).  */
 494       deps_add_default_target (pfile->deps, fname);
 495     }
 496
 497   pfile->main_file
 498     = _cpp_find_file (pfile, fname, &pfile->no_search_path, false, 0);
 499   if (_cpp_find_failed (pfile->main_file))
 500     return NULL;
 501
 502   _cpp_stack_file (pfile, pfile->main_file, false);
 503
 504   /* For foo.i, read the original filename foo.c now, for the benefit
 505      of the front ends.  */
 506   if (CPP_OPTION (pfile, preprocessed))
 507     {
 508       read_original_filename (pfile);
 509       fname = pfile->line_table->maps[pfile->line_table->used-1].to_file;
 510     }
 511   return fname;
 512 }
 513
 514 /* For preprocessed files, if the first tokens are of the form # NUM.
 515    handle the directive so we know the original file name.  This will
 516    generate file_change callbacks, which the front ends must handle
 517    appropriately given their state of initialization.  */
 518 static void
 519 read_original_filename (cpp_reader *pfile)
 520 {
 521   const cpp_token *token, *token1;
 522
 523   /* Lex ahead; if the first tokens are of the form # NUM, then
 524      process the directive, otherwise back up.  */
 525   token = _cpp_lex_direct (pfile);
 526   if (token->type == CPP_HASH)
 527     {
 528       pfile->state.in_directive = 1;
 529       token1 = _cpp_lex_direct (pfile);
 530       _cpp_backup_tokens (pfile, 1);
 531       pfile->state.in_directive = 0;
 532
 533       /* If it's a #line directive, handle it.  */
 534       if (token1->type == CPP_NUMBER)
 535         {
 536           _cpp_handle_directive (pfile, token->flags & PREV_WHITE);
 537           read_original_directory (pfile);
 538           return;
 539         }
 540     }
 541
 542   /* Backup as if nothing happened.  */
 543   _cpp_backup_tokens (pfile, 1);
 544 }
 545
 546 /* For preprocessed files, if the tokens following the first filename
 547    line is of the form # <line> "/path/name//", handle the
 548    directive so we know the original current directory.  */
 549 static void
 550 read_original_directory (cpp_reader *pfile)
 551 {
 552   const cpp_token *hash, *token;
 553
 554   /* Lex ahead; if the first tokens are of the form # NUM, then
 555      process the directive, otherwise back up.  */
 556   hash = _cpp_lex_direct (pfile);
 557   if (hash->type != CPP_HASH)
 558     {
 559       _cpp_backup_tokens (pfile, 1);
 560       return;
 561     }
 562
 563   token = _cpp_lex_direct (pfile);
 564
 565   if (token->type != CPP_NUMBER)
 566     {
 567       _cpp_backup_tokens (pfile, 2);
 568       return;
 569     }
 570
 571   token = _cpp_lex_direct (pfile);
 572
 573   if (token->type != CPP_STRING
 574       || ! (token->val.str.len >= 5
 575             && token->val.str.text[token->val.str.len-2] == '/'
 576             && token->val.str.text[token->val.str.len-3] == '/'))
 577     {
 578       _cpp_backup_tokens (pfile, 3);
 579       return;
 580     }
 581
 582   if (pfile->cb.dir_change)
 583     {
 584       char *debugdir = (char *) alloca (token->val.str.len - 3);
 585
 586       memcpy (debugdir, (const char *) token->val.str.text + 1,
 587               token->val.str.len - 4);
 588       debugdir[token->val.str.len - 4] = '\0';
 589
 590       pfile->cb.dir_change (pfile, debugdir);
 591     }
 592 }
 593
 594 /* This is called at the end of preprocessing.  It pops the last
 595    buffer and writes dependency output, and returns the number of
 596    errors.
 597
 598    Maybe it should also reset state, such that you could call
 599    cpp_start_read with a new filename to restart processing.  */
 600 int
 601 cpp_finish (cpp_reader *pfile, FILE *deps_stream)
 602 {
 603   /* Warn about unused macros before popping the final buffer.  */
 604   if (CPP_OPTION (pfile, warn_unused_macros))
 605     cpp_forall_identifiers (pfile, _cpp_warn_if_unused_macro, NULL);
 606
 607   /* lex.c leaves the final buffer on the stack.  This it so that
 608      it returns an unending stream of CPP_EOFs to the client.  If we
 609      popped the buffer, we'd dereference a NULL buffer pointer and
 610      segfault.  It's nice to allow the client to do worry-free excess
 611      cpp_get_token calls.  */
 612   while (pfile->buffer)
 613     _cpp_pop_buffer (pfile);
 614
 615   /* Don't write the deps file if there are errors.  */
 616   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE
 617       && deps_stream && pfile->errors == 0)
 618     {
 619       deps_write (pfile->deps, deps_stream, 72);
 620
 621       if (CPP_OPTION (pfile, deps.phony_targets))
 622         deps_phony_targets (pfile->deps, deps_stream);
 623     }
 624
 625   /* Report on headers that could use multiple include guards.  */
 626   if (CPP_OPTION (pfile, print_include_names))
 627     _cpp_report_missing_guards (pfile);
 628
 629   return pfile->errors;
 630 }
 631
 632 static void
 633 post_options (cpp_reader *pfile)
 634 {
 635   /* -Wtraditional is not useful in C++ mode.  */
 636   if (CPP_OPTION (pfile, cplusplus))
 637     CPP_OPTION (pfile, warn_traditional) = 0;
 638
 639   /* Permanently disable macro expansion if we are rescanning
 640      preprocessed text.  Read preprocesed source in ISO mode.  */
 641   if (CPP_OPTION (pfile, preprocessed))
 642     {
 643       if (!CPP_OPTION (pfile, directives_only))
 644         pfile->state.prevent_expansion = 1;
 645       CPP_OPTION (pfile, traditional) = 0;
 646     }
 647
 648   if (CPP_OPTION (pfile, warn_trigraphs) == 2)
 649     CPP_OPTION (pfile, warn_trigraphs) = !CPP_OPTION (pfile, trigraphs);
 650
 651   if (CPP_OPTION (pfile, traditional))
 652     {
 653       CPP_OPTION (pfile, cplusplus_comments) = 0;
 654
 655       /* Traditional CPP does not accurately track column information.  */
 656       CPP_OPTION (pfile, show_column) = 0;
 657       CPP_OPTION (pfile, trigraphs) = 0;
 658       CPP_OPTION (pfile, warn_trigraphs) = 0;
 659     }
 660 }