NEWS

   1 Bison News
   2 ----------
   3
   4 Changes in version 2.2, 2006-05-09:
   5
   6 * The distribution terms for all Bison-generated parsers now permit
   7   using the parsers in nonfree programs.  Previously, this permission
   8   was granted only for Bison-generated LALR(1) parsers in C.
   9
  10 * %name-prefix changes the namespace name in C++ outputs.
  11
  12 * The C++ parsers export their token_type.
  13
  14 * Bison now allows multiple %union declarations, and concatenates
  15   their contents together.
  16
  17 * New warning: unused values
  18   Right-hand side symbols whose values are not used are reported,
  19   if the symbols have destructors.  For instance:
  20
  21      exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
  22         | exp "+" exp
  23         ;
  24
  25   will trigger a warning about $$ and $5 in the first rule, and $3 in
  26   the second ($1 is copied to $$ by the default rule).  This example
  27   most likely contains three errors, and could be rewritten as:
  28
  29      exp: exp "?" exp ":" exp
  30             { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
  31         | exp "+" exp
  32             { $$ = $1 ? $1 : $3; if ($1) free ($3); }
  33         ;
  34
  35   However, if the original actions were really intended, memory leaks
  36   and all, the warnings can be suppressed by letting Bison believe the
  37   values are used, e.g.:
  38
  39      exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
  40         | exp "+" exp         { $$ = $1; (void) $3; }
  41         ;
  42
  43   If there are mid-rule actions, the warning is issued if no action
  44   uses it.  The following triggers no warning: $1 and $3 are used.
  45
  46      exp: exp { push ($1); } '+' exp { push ($3); sum (); };
  47
  48   The warning is intended to help catching lost values and memory leaks.
  49   If a value is ignored, its associated memory typically is not reclaimed.
  50
  51 * %destructor vs. YYABORT, YYACCEPT, and YYERROR.
  52   Destructors are now called when user code invokes YYABORT, YYACCEPT,
  53   and YYERROR, for all objects on the stack, other than objects
  54   corresponding to the right-hand side of the current rule.
  55
  56 * %expect, %expect-rr
  57   Incorrect numbers of expected conflicts are now actual errors,
  58   instead of warnings.
  59
  60 * GLR, YACC parsers.
  61   The %parse-params are available in the destructors (and the
  62   experimental printers) as per the documentation.
  63
  64 * Bison now warns if it finds a stray `$' or `@' in an action.
  65
  66 * %require "VERSION"
  67   This specifies that the grammar file depends on features implemented
  68   in Bison version VERSION or higher.
  69
  70 * lalr1.cc: The token and value types are now class members.
  71   The tokens were defined as free form enums and cpp macros.  YYSTYPE
  72   was defined as a free form union.  They are now class members:
  73   tokens are enumerations of the `yy::parser::token' struct, and the
  74   semantic values have the `yy::parser::semantic_type' type.
  75
  76   If you do not want or can update to this scheme, the directive
  77   `%define "global_tokens_and_yystype" "1"' triggers the global
  78   definition of tokens and YYSTYPE.  This change is suitable both
  79   for previous releases of Bison, and this one.
  80
  81   If you wish to update, then make sure older version of Bison will
  82   fail using `%require "2.1a"'.
  83
  84 * DJGPP support added.
  85 \f
  86 Changes in version 2.1, 2005-09-16:
  87
  88 * The C++ lalr1.cc skeleton supports %lex-param.
  89
  90 * Bison-generated parsers now support the translation of diagnostics like
  91   "syntax error" into languages other than English.  The default
  92   language is still English.  For details, please see the new
  93   Internationalization section of the Bison manual.  Software
  94   distributors should also see the new PACKAGING file.  Thanks to
  95   Bruno Haible for this new feature.
  96
  97 * Wording in the Bison-generated parsers has been changed slightly to
  98   simplify translation.  In particular, the message "memory exhausted"
  99   has replaced "parser stack overflow", as the old message was not
 100   always accurate for modern Bison-generated parsers.
 101
 102 * Destructors are now called when the parser aborts, for all symbols left
 103   behind on the stack.  Also, the start symbol is now destroyed after a
 104   successful parse.  In both cases, the behavior was formerly inconsistent.
 105
 106 * When generating verbose diagnostics, Bison-generated parsers no longer
 107   quote the literal strings associated with tokens.  For example, for
 108   a syntax error associated with '%token NUM "number"' they might
 109   print 'syntax error, unexpected number' instead of 'syntax error,
 110   unexpected "number"'.
 111 \f
 112 Changes in version 2.0, 2004-12-25:
 113
 114 * Possibly-incompatible changes
 115
 116   - Bison-generated parsers no longer default to using the alloca function
 117     (when available) to extend the parser stack, due to widespread
 118     problems in unchecked stack-overflow detection.  You can "#define
 119     YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read
 120     the manual to determine safe values for YYMAXDEPTH in that case.
 121
 122   - Error token location.
 123     During error recovery, the location of the syntax error is updated
 124     to cover the whole sequence covered by the error token: it includes
 125     the shifted symbols thrown away during the first part of the error
 126     recovery, and the lookahead rejected during the second part.
 127
 128   - Semicolon changes:
 129     . Stray semicolons are no longer allowed at the start of a grammar.
 130     . Semicolons are now required after in-grammar declarations.
 131
 132   - Unescaped newlines are no longer allowed in character constants or
 133     string literals.  They were never portable, and GCC 3.4.0 has
 134     dropped support for them.  Better diagnostics are now generated if
 135     forget a closing quote.
 136
 137   - NUL bytes are no longer allowed in Bison string literals, unfortunately.
 138
 139 * New features
 140
 141   - GLR grammars now support locations.
 142
 143   - New directive: %initial-action.
 144     This directive allows the user to run arbitrary code (including
 145     initializing @$) from yyparse before parsing starts.
 146
 147   - A new directive "%expect-rr N" specifies the expected number of
 148     reduce/reduce conflicts in GLR parsers.
 149
 150   - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
 151     This is a GNU extension.
 152
 153   - The option `--report=lookahead' was changed to `--report=look-ahead'.
 154     The old spelling still works, but is not documented and will be
 155     removed.
 156
 157   - Experimental %destructor support has been added to lalr1.cc.
 158
 159   - New configure option --disable-yacc, to disable installation of the
 160     yacc command and -ly library introduced in 1.875 for POSIX conformance.
 161
 162 * Bug fixes
 163
 164   - For now, %expect-count violations are now just warnings, not errors.
 165     This is for compatibility with Bison 1.75 and earlier (when there are
 166     reduce/reduce conflicts) and with Bison 1.30 and earlier (when there
 167     are too many or too few shift/reduce conflicts).  However, in future
 168     versions of Bison we plan to improve the %expect machinery so that
 169     these violations will become errors again.
 170
 171   - Within Bison itself, numbers (e.g., goto numbers) are no longer
 172     arbitrarily limited to 16-bit counts.
 173
 174   - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.
 175 \f
 176 Changes in version 1.875, 2003-01-01:
 177
 178 * The documentation license has been upgraded to version 1.2
 179   of the GNU Free Documentation License.
 180
 181 * syntax error processing
 182
 183   - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
 184     locations too.  This fixes bugs in error-location computation.
 185
 186   - %destructor
 187     It is now possible to reclaim the memory associated to symbols
 188     discarded during error recovery.  This feature is still experimental.
 189
 190   - %error-verbose
 191     This new directive is preferred over YYERROR_VERBOSE.
 192
 193   - #defining yyerror to steal internal variables is discouraged.
 194     It is not guaranteed to work forever.
 195
 196 * POSIX conformance
 197
 198   - Semicolons are once again optional at the end of grammar rules.
 199     This reverts to the behavior of Bison 1.33 and earlier, and improves
 200     compatibility with Yacc.
 201
 202   - `parse error' -> `syntax error'
 203     Bison now uniformly uses the term `syntax error'; formerly, the code
 204     and manual sometimes used the term `parse error' instead.  POSIX
 205     requires `syntax error' in diagnostics, and it was thought better to
 206     be consistent.
 207
 208   - The documentation now emphasizes that yylex and yyerror must be
 209     declared before use.  C99 requires this.
 210
 211   - Bison now parses C99 lexical constructs like UCNs and
 212     backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
 213
 214   - File names are properly escaped in C output.  E.g., foo\bar.y is
 215     output as "foo\\bar.y".
 216
 217   - Yacc command and library now available
 218     The Bison distribution now installs a `yacc' command, as POSIX requires.
 219     Also, Bison now installs a small library liby.a containing
 220     implementations of Yacc-compatible yyerror and main functions.
 221     This library is normally not useful, but POSIX requires it.
 222
 223   - Type clashes now generate warnings, not errors.
 224
 225   - If the user does not define YYSTYPE as a macro, Bison now declares it
 226     using typedef instead of defining it as a macro.
 227     For consistency, YYLTYPE is also declared instead of defined.
 228
 229 * Other compatibility issues
 230
 231   - %union directives can now have a tag before the `{', e.g., the
 232     directive `%union foo {...}' now generates the C code
 233     `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
 234     The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
 235     For consistency, YYLTYPE's struct tag is now `YYLTYPE' not `yyltype'.
 236     This is for compatibility with both Yacc and Bison 1.35.
 237
 238   - `;' is output before the terminating `}' of an action, for
 239     compatibility with Bison 1.35.
 240
 241   - Bison now uses a Yacc-style format for conflict reports, e.g.,
 242     `conflicts: 2 shift/reduce, 1 reduce/reduce'.
 243
 244   - `yystype' and `yyltype' are now obsolescent macros instead of being
 245     typedefs or tags; they are no longer documented and are planned to be
 246     withdrawn in a future release.
 247
 248 * GLR parser notes
 249
 250   - GLR and inline
 251     Users of Bison have to decide how they handle the portability of the
 252     C keyword `inline'.
 253
 254   - `parsing stack overflow...' -> `parser stack overflow'
 255     GLR parsers now report `parser stack overflow' as per the Bison manual.
 256
 257 * Bison now warns if it detects conflicting outputs to the same file,
 258   e.g., it generates a warning for `bison -d -o foo.h foo.y' since
 259   that command outputs both code and header to foo.h.
 260
 261 * #line in output files
 262   - --no-line works properly.
 263
 264 * Bison can no longer be built by a K&R C compiler; it requires C89 or
 265   later to be built.  This change originally took place a few versions
 266   ago, but nobody noticed until we recently asked someone to try
 267   building Bison with a K&R C compiler.
 268 \f
 269 Changes in version 1.75, 2002-10-14:
 270
 271 * Bison should now work on 64-bit hosts.
 272
 273 * Indonesian translation thanks to Tedi Heriyanto.
 274
 275 * GLR parsers
 276   Fix spurious parse errors.
 277
 278 * Pure parsers
 279   Some people redefine yyerror to steal yyparse' private variables.
 280   Reenable this trick until an official feature replaces it.
 281
 282 * Type Clashes
 283   In agreement with POSIX and with other Yaccs, leaving a default
 284   action is valid when $$ is untyped, and $1 typed:
 285
 286         untyped: ... typed;
 287
 288   but the converse remains an error:
 289
 290         typed: ... untyped;
 291
 292 * Values of mid-rule actions
 293   The following code:
 294
 295         foo: { ... } { $$ = $1; } ...
 296
 297   was incorrectly rejected: $1 is defined in the second mid-rule
 298   action, and is equal to the $$ of the first mid-rule action.
 299 \f
 300 Changes in version 1.50, 2002-10-04:
 301
 302 * GLR parsing
 303   The declaration
 304      %glr-parser
 305   causes Bison to produce a Generalized LR (GLR) parser, capable of handling
 306   almost any context-free grammar, ambiguous or not.  The new declarations
 307   %dprec and %merge on grammar rules allow parse-time resolution of
 308   ambiguities.  Contributed by Paul Hilfinger.
 309
 310   Unfortunately Bison 1.50 does not work properly on 64-bit hosts
 311   like the Alpha, so please stick to 32-bit hosts for now.
 312
 313 * Output Directory
 314   When not in Yacc compatibility mode, when the output file was not
 315   specified, running `bison foo/bar.y' created `foo/bar.c'.  It
 316   now creates `bar.c'.
 317
 318 * Undefined token
 319   The undefined token was systematically mapped to 2 which prevented
 320   the use of 2 by the user.  This is no longer the case.
 321
 322 * Unknown token numbers
 323   If yylex returned an out of range value, yyparse could die.  This is
 324   no longer the case.
 325
 326 * Error token
 327   According to POSIX, the error token must be 256.
 328   Bison extends this requirement by making it a preference: *if* the
 329   user specified that one of her tokens is numbered 256, then error
 330   will be mapped onto another number.
 331
 332 * Verbose error messages
 333   They no longer report `..., expecting error or...' for states where
 334   error recovery is possible.
 335
 336 * End token
 337   Defaults to `$end' instead of `$'.
 338
 339 * Error recovery now conforms to documentation and to POSIX
 340   When a Bison-generated parser encounters a syntax error, it now pops
 341   the stack until it finds a state that allows shifting the error
 342   token.  Formerly, it popped the stack until it found a state that
 343   allowed some non-error action other than a default reduction on the
 344   error token.  The new behavior has long been the documented behavior,
 345   and has long been required by POSIX.  For more details, please see
 346   Paul Eggert, "Reductions during Bison error handling" (2002-05-20)
 347   <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>.
 348
 349 * Traces
 350   Popped tokens and nonterminals are now reported.
 351
 352 * Larger grammars
 353   Larger grammars are now supported (larger token numbers, larger grammar
 354   size (= sum of the LHS and RHS lengths), larger LALR tables).
 355   Formerly, many of these numbers ran afoul of 16-bit limits;
 356   now these limits are 32 bits on most hosts.
 357
 358 * Explicit initial rule
 359   Bison used to play hacks with the initial rule, which the user does
 360   not write.  It is now explicit, and visible in the reports and
 361   graphs as rule 0.
 362
 363 * Useless rules
 364   Before, Bison reported the useless rules, but, although not used,
 365   included them in the parsers.  They are now actually removed.
 366
 367 * Useless rules, useless nonterminals
 368   They are now reported, as a warning, with their locations.
 369
 370 * Rules never reduced
 371   Rules that can never be reduced because of conflicts are now
 372   reported.
 373
 374 * Incorrect `Token not used'
 375   On a grammar such as
 376
 377            %token useless useful
 378            %%
 379            exp: '0' %prec useful;
 380
 381   where a token was used to set the precedence of the last rule,
 382   bison reported both `useful' and `useless' as useless tokens.
 383
 384 * Revert the C++ namespace changes introduced in 1.31
 385   as they caused too many portability hassles.
 386
 387 * Default locations
 388   By an accident of design, the default computation of @$ was
 389   performed after another default computation was performed: @$ = @1.
 390   The latter is now removed: YYLLOC_DEFAULT is fully responsible of
 391   the computation of @$.
 392
 393 * Token end-of-file
 394   The token end of file may be specified by the user, in which case,
 395   the user symbol is used in the reports, the graphs, and the verbose
 396   error messages instead of `$end', which remains being the default.
 397   For instance
 398      %token MYEOF 0
 399   or
 400      %token MYEOF 0 "end of file"
 401
 402 * Semantic parser
 403   This old option, which has been broken for ages, is removed.
 404
 405 * New translations
 406   Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
 407   Croatian, thanks to Denis Lackovic.
 408
 409 * Incorrect token definitions
 410   When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
 411
 412 * Token definitions as enums
 413   Tokens are output both as the traditional #define's, and, provided
 414   the compiler supports ANSI C or is a C++ compiler, as enums.
 415   This lets debuggers display names instead of integers.
 416
 417 * Reports
 418   In addition to --verbose, bison supports --report=THINGS, which
 419   produces additional information:
 420   - itemset
 421     complete the core item sets with their closure
 422   - lookahead [changed to `look-ahead' in 1.875e and later]
 423     explicitly associate look-ahead tokens to items
 424   - solved
 425     describe shift/reduce conflicts solving.
 426     Bison used to systematically output this information on top of
 427     the report.  Solved conflicts are now attached to their states.
 428
 429 * Type clashes
 430   Previous versions don't complain when there is a type clash on
 431   the default action if the rule has a mid-rule action, such as in:
 432
 433       %type <foo> bar
 434       %%
 435       bar: '0' {} '0';
 436
 437   This is fixed.
 438
 439 * GNU M4 is now required when using Bison.
 440 \f
 441 Changes in version 1.35, 2002-03-25:
 442
 443 * C Skeleton
 444   Some projects use Bison's C parser with C++ compilers, and define
 445   YYSTYPE as a class.  The recent adjustment of C parsers for data
 446   alignment and 64 bit architectures made this impossible.
 447
 448   Because for the time being no real solution for C++ parser
 449   generation exists, kludges were implemented in the parser to
 450   maintain this use.  In the future, when Bison has C++ parsers, this
 451   kludge will be disabled.
 452
 453   This kludge also addresses some C++ problems when the stack was
 454   extended.
 455 \f
 456 Changes in version 1.34, 2002-03-12:
 457
 458 * File name clashes are detected
 459   $ bison foo.y -d -o foo.x
 460   fatal error: header and parser would both be named `foo.x'
 461
 462 * A missing `;' at the end of a rule triggers a warning
 463   In accordance with POSIX, and in agreement with other
 464   Yacc implementations, Bison will mandate this semicolon in the near
 465   future.  This eases the implementation of a Bison parser of Bison
 466   grammars by making this grammar LALR(1) instead of LR(2).  To
 467   facilitate the transition, this release introduces a warning.
 468
 469 * Revert the C++ namespace changes introduced in 1.31, as they caused too
 470   many portability hassles.
 471
 472 * DJGPP support added.
 473
 474 * Fix test suite portability problems.
 475 \f
 476 Changes in version 1.33, 2002-02-07:
 477
 478 * Fix C++ issues
 479   Groff could not be compiled for the definition of size_t was lacking
 480   under some conditions.
 481
 482 * Catch invalid @n
 483   As is done with $n.
 484 \f
 485 Changes in version 1.32, 2002-01-23:
 486
 487 * Fix Yacc output file names
 488
 489 * Portability fixes
 490
 491 * Italian, Dutch translations
 492 \f
 493 Changes in version 1.31, 2002-01-14:
 494
 495 * Many Bug Fixes
 496
 497 * GNU Gettext and %expect
 498   GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
 499   Bison dies on incorrect %expectations, we fear there will be
 500   too many bug reports for Gettext, so _for the time being_, %expect
 501   does not trigger an error when the input file is named `plural.y'.
 502
 503 * Use of alloca in parsers
 504   If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
 505   malloc exclusively.  Since 1.29, but was not NEWS'ed.
 506
 507   alloca is used only when compiled with GCC, to avoid portability
 508   problems as on AIX.
 509
 510 * yyparse now returns 2 if memory is exhausted; formerly it dumped core.
 511
 512 * When the generated parser lacks debugging code, YYDEBUG is now 0
 513   (as POSIX requires) instead of being undefined.
 514
 515 * User Actions
 516   Bison has always permitted actions such as { $$ = $1 }: it adds the
 517   ending semicolon.  Now if in Yacc compatibility mode, the semicolon
 518   is no longer output: one has to write { $$ = $1; }.
 519
 520 * Better C++ compliance
 521   The output parsers try to respect C++ namespaces.
 522   [This turned out to be a failed experiment, and it was reverted later.]
 523
 524 * Reduced Grammars
 525   Fixed bugs when reporting useless nonterminals.
 526
 527 * 64 bit hosts
 528   The parsers work properly on 64 bit hosts.
 529
 530 * Error messages
 531   Some calls to strerror resulted in scrambled or missing error messages.
 532
 533 * %expect
 534   When the number of shift/reduce conflicts is correct, don't issue
 535   any warning.
 536
 537 * The verbose report includes the rule line numbers.
 538
 539 * Rule line numbers are fixed in traces.
 540
 541 * Swedish translation
 542
 543 * Parse errors
 544   Verbose parse error messages from the parsers are better looking.
 545   Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
 546      Now: parse error: unexpected '/', expecting "number" or '-' or '('
 547
 548 * Fixed parser memory leaks.
 549   When the generated parser was using malloc to extend its stacks, the
 550   previous allocations were not freed.
 551
 552 * Fixed verbose output file.
 553   Some newlines were missing.
 554   Some conflicts in state descriptions were missing.
 555
 556 * Fixed conflict report.
 557   Option -v was needed to get the result.
 558
 559 * %expect
 560   Was not used.
 561   Mismatches are errors, not warnings.
 562
 563 * Fixed incorrect processing of some invalid input.
 564
 565 * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
 566
 567 * Fixed some typos in the documentation.
 568
 569 * %token MY_EOF 0 is supported.
 570   Before, MY_EOF was silently renumbered as 257.
 571
 572 * doc/refcard.tex is updated.
 573
 574 * %output, %file-prefix, %name-prefix.
 575   New.
 576
 577 * --output
 578   New, aliasing `--output-file'.
 579 \f
 580 Changes in version 1.30, 2001-10-26:
 581
 582 * `--defines' and `--graph' have now an optional argument which is the
 583   output file name. `-d' and `-g' do not change; they do not take any
 584   argument.
 585
 586 * `%source_extension' and `%header_extension' are removed, failed
 587   experiment.
 588
 589 * Portability fixes.
 590 \f
 591 Changes in version 1.29, 2001-09-07:
 592
 593 * The output file does not define const, as this caused problems when used
 594   with common autoconfiguration schemes.  If you still use ancient compilers
 595   that lack const, compile with the equivalent of the C compiler option
 596   `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
 597
 598 * Added `-g' and `--graph'.
 599
 600 * The Bison manual is now distributed under the terms of the GNU FDL.
 601
 602 * The input and the output files has automatically a similar extension.
 603
 604 * Russian translation added.
 605
 606 * NLS support updated; should hopefully be less troublesome.
 607
 608 * Added the old Bison reference card.
 609
 610 * Added `--locations' and `%locations'.
 611
 612 * Added `-S' and `--skeleton'.
 613
 614 * `%raw', `-r', `--raw' is disabled.
 615
 616 * Special characters are escaped when output.  This solves the problems
 617   of the #line lines with path names including backslashes.
 618
 619 * New directives.
 620   `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
 621   `%debug', `%source_extension' and `%header_extension'.
 622
 623 * @$
 624   Automatic location tracking.
 625 \f
 626 Changes in version 1.28, 1999-07-06:
 627
 628 * Should compile better now with K&R compilers.
 629
 630 * Added NLS.
 631
 632 * Fixed a problem with escaping the double quote character.
 633
 634 * There is now a FAQ.
 635 \f
 636 Changes in version 1.27:
 637
 638 * The make rule which prevented bison.simple from being created on
 639   some systems has been fixed.
 640 \f
 641 Changes in version 1.26:
 642
 643 * Bison now uses automake.
 644
 645 * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
 646
 647 * Token numbers now start at 257 as previously documented, not 258.
 648
 649 * Bison honors the TMPDIR environment variable.
 650
 651 * A couple of buffer overruns have been fixed.
 652
 653 * Problems when closing files should now be reported.
 654
 655 * Generated parsers should now work even on operating systems which do
 656   not provide alloca().
 657 \f
 658 Changes in version 1.25, 1995-10-16:
 659
 660 * Errors in the input grammar are not fatal; Bison keeps reading
 661 the grammar file, and reports all the errors found in it.
 662
 663 * Tokens can now be specified as multiple-character strings: for
 664 example, you could use "<=" for a token which looks like <=, instead
 665 of chosing a name like LESSEQ.
 666
 667 * The %token_table declaration says to write a table of tokens (names
 668 and numbers) into the parser file.  The yylex function can use this
 669 table to recognize multiple-character string tokens, or for other
 670 purposes.
 671
 672 * The %no_lines declaration says not to generate any #line preprocessor
 673 directives in the parser file.
 674
 675 * The %raw declaration says to use internal Bison token numbers, not
 676 Yacc-compatible token numbers, when token names are defined as macros.
 677
 678 * The --no-parser option produces the parser tables without including
 679 the parser engine; a project can now use its own parser engine.
 680 The actions go into a separate file called NAME.act, in the form of
 681 a switch statement body.
 682 \f
 683 Changes in version 1.23:
 684
 685 The user can define YYPARSE_PARAM as the name of an argument to be
 686 passed into yyparse.  The argument should have type void *.  It should
 687 actually point to an object.  Grammar actions can access the variable
 688 by casting it to the proper pointer type.
 689
 690 Line numbers in output file corrected.
 691 \f
 692 Changes in version 1.22:
 693
 694 --help option added.
 695 \f
 696 Changes in version 1.20:
 697
 698 Output file does not redefine const for C++.
 699
 700 Local Variables:
 701 mode: outline
 702 End:
 703
 704 -----
 705
 706 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
 707 2004, 2005, 2006 Free Software Foundation, Inc.
 708
 709 This file is part of Bison, the GNU Compiler Compiler.
 710
 711 Bison is free software; you can redistribute it and/or modify
 712 it under the terms of the GNU General Public License as published by
 713 the Free Software Foundation; either version 2, or (at your option)
 714 any later version.
 715
 716 Bison is distributed in the hope that it will be useful,
 717 but WITHOUT ANY WARRANTY; without even the implied warranty of
 718 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 719 GNU General Public License for more details.
 720
 721 You should have received a copy of the GNU General Public License
 722 along with autoconf; see the file COPYING.  If not, write to
 723 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 724 Boston, MA 02110-1301, USA.