NEWS

   1 Bison News
   2 ----------
   3
   4 Changes in version 2.3+:
   5
   6 * Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
   7   `--yacc', or `%yacc'), Bison no longer generates #define statements for
   8   associating token numbers with token names.  Removing the #define statements
   9   helps to sanitize the global namespace during preprocessing, but POSIX Yacc
  10   requires them.  Bison still generates an enum for token names in all cases.
  11
  12 * Handling of prologue blocks is now more consistent but potentially backward
  13   incompatible.
  14
  15   As before, you declare prologue blocks in your grammar file with the
  16   `%{ ... %}' syntax.  To generate the pre-prologue, Bison concatenates all
  17   prologue blocks that you've declared before any %union.  If you've declared a
  18   %union, Bison concatenates all prologue blocks that you've declared after it
  19   to generate the post-prologue.  (The new %before-definitions and
  20   %after-definitions have a similar effect as %union on the prologues.  See
  21   below.)
  22
  23   Previous versions of Bison inserted the pre-prologue into both the header
  24   file and the code file in all cases except for LALR(1) parsers in C.  In the
  25   latter case, Bison inserted it only into the code file.  For parsers in C++,
  26   the point of insertion was before any token definitions (which associate
  27   token numbers with names).  For parsers in C, the point of insertion was
  28   after the token definitions.
  29
  30   Now, Bison never inserts the pre-prologue into the header file.  In the code
  31   file, it always inserts it before the token definitions.
  32
  33 * Bison now provides the %before-definitions and %after-definitions directives.
  34
  35   For example, in your grammar file:
  36
  37     %{
  38       /* A pre-prologue block.  For Yacc portability, Bison no longer puts this
  39        * in the header file.  In the code file, Bison inserts it before any
  40        * %before-definitions blocks.  */
  41     %}
  42     %before-definitions {
  43       /* Bison inserts this into both the header file and code file.  In both
  44        * files, the point of insertion is before any Bison-generated token,
  45        * semantic type, location type, and class definitions.  This is a good
  46        * place to define %union dependencies, for example.  */
  47     }
  48     %union {
  49       /* With previous versions of Bison, the first %union in your grammar file
  50        * separated the pre-prologue blocks from the post-prologue blocks.  Now,
  51        * the first %union, %before-definitions, or %after-definitions does
  52        * that.  */
  53     }
  54     %after-definitions {
  55       /* If you want something in the header file and in the code file and it
  56        * depends on any of the Bison-generated definitions in the header file,
  57        * put it here.  */
  58     }
  59     %{
  60       /* A post-prologue block.  If you want something in the code file but not
  61        * in the header file and it depends on Bison-generated definitions, put
  62        * it here.  In the code file, Bison inserts it after any
  63        * %after-definitions blocks.  */
  64     %}
  65
  66 * The option `--report=look-ahead' has been changed to `--report=lookahead'.
  67   The old spelling still works, but is not documented and may be removed
  68   in a future release.
  69
  70 Changes in version 2.3, 2006-06-05:
  71
  72 * GLR grammars should now use `YYRECOVERING ()' instead of `YYRECOVERING',
  73   for compatibility with LALR(1) grammars.
  74
  75 * It is now documented that any definition of YYSTYPE or YYLTYPE should
  76   be to a type name that does not contain parentheses or brackets.
  77
  78 Changes in version 2.2, 2006-05-19:
  79
  80 * The distribution terms for all Bison-generated parsers now permit
  81   using the parsers in nonfree programs.  Previously, this permission
  82   was granted only for Bison-generated LALR(1) parsers in C.
  83
  84 * %name-prefix changes the namespace name in C++ outputs.
  85
  86 * The C++ parsers export their token_type.
  87
  88 * Bison now allows multiple %union declarations, and concatenates
  89   their contents together.
  90
  91 * New warning: unused values
  92   Right-hand side symbols whose values are not used are reported,
  93   if the symbols have destructors.  For instance:
  94
  95      exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
  96         | exp "+" exp
  97         ;
  98
  99   will trigger a warning about $$ and $5 in the first rule, and $3 in
 100   the second ($1 is copied to $$ by the default rule).  This example
 101   most likely contains three errors, and could be rewritten as:
 102
 103      exp: exp "?" exp ":" exp
 104             { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
 105         | exp "+" exp
 106             { $$ = $1 ? $1 : $3; if ($1) free ($3); }
 107         ;
 108
 109   However, if the original actions were really intended, memory leaks
 110   and all, the warnings can be suppressed by letting Bison believe the
 111   values are used, e.g.:
 112
 113      exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
 114         | exp "+" exp         { $$ = $1; (void) $3; }
 115         ;
 116
 117   If there are mid-rule actions, the warning is issued if no action
 118   uses it.  The following triggers no warning: $1 and $3 are used.
 119
 120      exp: exp { push ($1); } '+' exp { push ($3); sum (); };
 121
 122   The warning is intended to help catching lost values and memory leaks.
 123   If a value is ignored, its associated memory typically is not reclaimed.
 124
 125 * %destructor vs. YYABORT, YYACCEPT, and YYERROR.
 126   Destructors are now called when user code invokes YYABORT, YYACCEPT,
 127   and YYERROR, for all objects on the stack, other than objects
 128   corresponding to the right-hand side of the current rule.
 129
 130 * %expect, %expect-rr
 131   Incorrect numbers of expected conflicts are now actual errors,
 132   instead of warnings.
 133
 134 * GLR, YACC parsers.
 135   The %parse-params are available in the destructors (and the
 136   experimental printers) as per the documentation.
 137
 138 * Bison now warns if it finds a stray `$' or `@' in an action.
 139
 140 * %require "VERSION"
 141   This specifies that the grammar file depends on features implemented
 142   in Bison version VERSION or higher.
 143
 144 * lalr1.cc: The token and value types are now class members.
 145   The tokens were defined as free form enums and cpp macros.  YYSTYPE
 146   was defined as a free form union.  They are now class members:
 147   tokens are enumerations of the `yy::parser::token' struct, and the
 148   semantic values have the `yy::parser::semantic_type' type.
 149
 150   If you do not want or can update to this scheme, the directive
 151   `%define "global_tokens_and_yystype" "1"' triggers the global
 152   definition of tokens and YYSTYPE.  This change is suitable both
 153   for previous releases of Bison, and this one.
 154
 155   If you wish to update, then make sure older version of Bison will
 156   fail using `%require "2.2"'.
 157
 158 * DJGPP support added.
 159 \f
 160 Changes in version 2.1, 2005-09-16:
 161
 162 * The C++ lalr1.cc skeleton supports %lex-param.
 163
 164 * Bison-generated parsers now support the translation of diagnostics like
 165   "syntax error" into languages other than English.  The default
 166   language is still English.  For details, please see the new
 167   Internationalization section of the Bison manual.  Software
 168   distributors should also see the new PACKAGING file.  Thanks to
 169   Bruno Haible for this new feature.
 170
 171 * Wording in the Bison-generated parsers has been changed slightly to
 172   simplify translation.  In particular, the message "memory exhausted"
 173   has replaced "parser stack overflow", as the old message was not
 174   always accurate for modern Bison-generated parsers.
 175
 176 * Destructors are now called when the parser aborts, for all symbols left
 177   behind on the stack.  Also, the start symbol is now destroyed after a
 178   successful parse.  In both cases, the behavior was formerly inconsistent.
 179
 180 * When generating verbose diagnostics, Bison-generated parsers no longer
 181   quote the literal strings associated with tokens.  For example, for
 182   a syntax error associated with '%token NUM "number"' they might
 183   print 'syntax error, unexpected number' instead of 'syntax error,
 184   unexpected "number"'.
 185 \f
 186 Changes in version 2.0, 2004-12-25:
 187
 188 * Possibly-incompatible changes
 189
 190   - Bison-generated parsers no longer default to using the alloca function
 191     (when available) to extend the parser stack, due to widespread
 192     problems in unchecked stack-overflow detection.  You can "#define
 193     YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read
 194     the manual to determine safe values for YYMAXDEPTH in that case.
 195
 196   - Error token location.
 197     During error recovery, the location of the syntax error is updated
 198     to cover the whole sequence covered by the error token: it includes
 199     the shifted symbols thrown away during the first part of the error
 200     recovery, and the lookahead rejected during the second part.
 201
 202   - Semicolon changes:
 203     . Stray semicolons are no longer allowed at the start of a grammar.
 204     . Semicolons are now required after in-grammar declarations.
 205
 206   - Unescaped newlines are no longer allowed in character constants or
 207     string literals.  They were never portable, and GCC 3.4.0 has
 208     dropped support for them.  Better diagnostics are now generated if
 209     forget a closing quote.
 210
 211   - NUL bytes are no longer allowed in Bison string literals, unfortunately.
 212
 213 * New features
 214
 215   - GLR grammars now support locations.
 216
 217   - New directive: %initial-action.
 218     This directive allows the user to run arbitrary code (including
 219     initializing @$) from yyparse before parsing starts.
 220
 221   - A new directive "%expect-rr N" specifies the expected number of
 222     reduce/reduce conflicts in GLR parsers.
 223
 224   - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
 225     This is a GNU extension.
 226
 227   - The option `--report=lookahead' was changed to `--report=look-ahead'.
 228     [However, this was changed back after 2.3.]
 229
 230   - Experimental %destructor support has been added to lalr1.cc.
 231
 232   - New configure option --disable-yacc, to disable installation of the
 233     yacc command and -ly library introduced in 1.875 for POSIX conformance.
 234
 235 * Bug fixes
 236
 237   - For now, %expect-count violations are now just warnings, not errors.
 238     This is for compatibility with Bison 1.75 and earlier (when there are
 239     reduce/reduce conflicts) and with Bison 1.30 and earlier (when there
 240     are too many or too few shift/reduce conflicts).  However, in future
 241     versions of Bison we plan to improve the %expect machinery so that
 242     these violations will become errors again.
 243
 244   - Within Bison itself, numbers (e.g., goto numbers) are no longer
 245     arbitrarily limited to 16-bit counts.
 246
 247   - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.
 248 \f
 249 Changes in version 1.875, 2003-01-01:
 250
 251 * The documentation license has been upgraded to version 1.2
 252   of the GNU Free Documentation License.
 253
 254 * syntax error processing
 255
 256   - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
 257     locations too.  This fixes bugs in error-location computation.
 258
 259   - %destructor
 260     It is now possible to reclaim the memory associated to symbols
 261     discarded during error recovery.  This feature is still experimental.
 262
 263   - %error-verbose
 264     This new directive is preferred over YYERROR_VERBOSE.
 265
 266   - #defining yyerror to steal internal variables is discouraged.
 267     It is not guaranteed to work forever.
 268
 269 * POSIX conformance
 270
 271   - Semicolons are once again optional at the end of grammar rules.
 272     This reverts to the behavior of Bison 1.33 and earlier, and improves
 273     compatibility with Yacc.
 274
 275   - `parse error' -> `syntax error'
 276     Bison now uniformly uses the term `syntax error'; formerly, the code
 277     and manual sometimes used the term `parse error' instead.  POSIX
 278     requires `syntax error' in diagnostics, and it was thought better to
 279     be consistent.
 280
 281   - The documentation now emphasizes that yylex and yyerror must be
 282     declared before use.  C99 requires this.
 283
 284   - Bison now parses C99 lexical constructs like UCNs and
 285     backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
 286
 287   - File names are properly escaped in C output.  E.g., foo\bar.y is
 288     output as "foo\\bar.y".
 289
 290   - Yacc command and library now available
 291     The Bison distribution now installs a `yacc' command, as POSIX requires.
 292     Also, Bison now installs a small library liby.a containing
 293     implementations of Yacc-compatible yyerror and main functions.
 294     This library is normally not useful, but POSIX requires it.
 295
 296   - Type clashes now generate warnings, not errors.
 297
 298   - If the user does not define YYSTYPE as a macro, Bison now declares it
 299     using typedef instead of defining it as a macro.
 300     For consistency, YYLTYPE is also declared instead of defined.
 301
 302 * Other compatibility issues
 303
 304   - %union directives can now have a tag before the `{', e.g., the
 305     directive `%union foo {...}' now generates the C code
 306     `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
 307     The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
 308     For consistency, YYLTYPE's struct tag is now `YYLTYPE' not `yyltype'.
 309     This is for compatibility with both Yacc and Bison 1.35.
 310
 311   - `;' is output before the terminating `}' of an action, for
 312     compatibility with Bison 1.35.
 313
 314   - Bison now uses a Yacc-style format for conflict reports, e.g.,
 315     `conflicts: 2 shift/reduce, 1 reduce/reduce'.
 316
 317   - `yystype' and `yyltype' are now obsolescent macros instead of being
 318     typedefs or tags; they are no longer documented and are planned to be
 319     withdrawn in a future release.
 320
 321 * GLR parser notes
 322
 323   - GLR and inline
 324     Users of Bison have to decide how they handle the portability of the
 325     C keyword `inline'.
 326
 327   - `parsing stack overflow...' -> `parser stack overflow'
 328     GLR parsers now report `parser stack overflow' as per the Bison manual.
 329
 330 * Bison now warns if it detects conflicting outputs to the same file,
 331   e.g., it generates a warning for `bison -d -o foo.h foo.y' since
 332   that command outputs both code and header to foo.h.
 333
 334 * #line in output files
 335   - --no-line works properly.
 336
 337 * Bison can no longer be built by a K&R C compiler; it requires C89 or
 338   later to be built.  This change originally took place a few versions
 339   ago, but nobody noticed until we recently asked someone to try
 340   building Bison with a K&R C compiler.
 341 \f
 342 Changes in version 1.75, 2002-10-14:
 343
 344 * Bison should now work on 64-bit hosts.
 345
 346 * Indonesian translation thanks to Tedi Heriyanto.
 347
 348 * GLR parsers
 349   Fix spurious parse errors.
 350
 351 * Pure parsers
 352   Some people redefine yyerror to steal yyparse' private variables.
 353   Reenable this trick until an official feature replaces it.
 354
 355 * Type Clashes
 356   In agreement with POSIX and with other Yaccs, leaving a default
 357   action is valid when $$ is untyped, and $1 typed:
 358
 359         untyped: ... typed;
 360
 361   but the converse remains an error:
 362
 363         typed: ... untyped;
 364
 365 * Values of mid-rule actions
 366   The following code:
 367
 368         foo: { ... } { $$ = $1; } ...
 369
 370   was incorrectly rejected: $1 is defined in the second mid-rule
 371   action, and is equal to the $$ of the first mid-rule action.
 372 \f
 373 Changes in version 1.50, 2002-10-04:
 374
 375 * GLR parsing
 376   The declaration
 377      %glr-parser
 378   causes Bison to produce a Generalized LR (GLR) parser, capable of handling
 379   almost any context-free grammar, ambiguous or not.  The new declarations
 380   %dprec and %merge on grammar rules allow parse-time resolution of
 381   ambiguities.  Contributed by Paul Hilfinger.
 382
 383   Unfortunately Bison 1.50 does not work properly on 64-bit hosts
 384   like the Alpha, so please stick to 32-bit hosts for now.
 385
 386 * Output Directory
 387   When not in Yacc compatibility mode, when the output file was not
 388   specified, running `bison foo/bar.y' created `foo/bar.c'.  It
 389   now creates `bar.c'.
 390
 391 * Undefined token
 392   The undefined token was systematically mapped to 2 which prevented
 393   the use of 2 by the user.  This is no longer the case.
 394
 395 * Unknown token numbers
 396   If yylex returned an out of range value, yyparse could die.  This is
 397   no longer the case.
 398
 399 * Error token
 400   According to POSIX, the error token must be 256.
 401   Bison extends this requirement by making it a preference: *if* the
 402   user specified that one of her tokens is numbered 256, then error
 403   will be mapped onto another number.
 404
 405 * Verbose error messages
 406   They no longer report `..., expecting error or...' for states where
 407   error recovery is possible.
 408
 409 * End token
 410   Defaults to `$end' instead of `$'.
 411
 412 * Error recovery now conforms to documentation and to POSIX
 413   When a Bison-generated parser encounters a syntax error, it now pops
 414   the stack until it finds a state that allows shifting the error
 415   token.  Formerly, it popped the stack until it found a state that
 416   allowed some non-error action other than a default reduction on the
 417   error token.  The new behavior has long been the documented behavior,
 418   and has long been required by POSIX.  For more details, please see
 419   Paul Eggert, "Reductions during Bison error handling" (2002-05-20)
 420   <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>.
 421
 422 * Traces
 423   Popped tokens and nonterminals are now reported.
 424
 425 * Larger grammars
 426   Larger grammars are now supported (larger token numbers, larger grammar
 427   size (= sum of the LHS and RHS lengths), larger LALR tables).
 428   Formerly, many of these numbers ran afoul of 16-bit limits;
 429   now these limits are 32 bits on most hosts.
 430
 431 * Explicit initial rule
 432   Bison used to play hacks with the initial rule, which the user does
 433   not write.  It is now explicit, and visible in the reports and
 434   graphs as rule 0.
 435
 436 * Useless rules
 437   Before, Bison reported the useless rules, but, although not used,
 438   included them in the parsers.  They are now actually removed.
 439
 440 * Useless rules, useless nonterminals
 441   They are now reported, as a warning, with their locations.
 442
 443 * Rules never reduced
 444   Rules that can never be reduced because of conflicts are now
 445   reported.
 446
 447 * Incorrect `Token not used'
 448   On a grammar such as
 449
 450            %token useless useful
 451            %%
 452            exp: '0' %prec useful;
 453
 454   where a token was used to set the precedence of the last rule,
 455   bison reported both `useful' and `useless' as useless tokens.
 456
 457 * Revert the C++ namespace changes introduced in 1.31
 458   as they caused too many portability hassles.
 459
 460 * Default locations
 461   By an accident of design, the default computation of @$ was
 462   performed after another default computation was performed: @$ = @1.
 463   The latter is now removed: YYLLOC_DEFAULT is fully responsible of
 464   the computation of @$.
 465
 466 * Token end-of-file
 467   The token end of file may be specified by the user, in which case,
 468   the user symbol is used in the reports, the graphs, and the verbose
 469   error messages instead of `$end', which remains being the default.
 470   For instance
 471      %token MYEOF 0
 472   or
 473      %token MYEOF 0 "end of file"
 474
 475 * Semantic parser
 476   This old option, which has been broken for ages, is removed.
 477
 478 * New translations
 479   Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
 480   Croatian, thanks to Denis Lackovic.
 481
 482 * Incorrect token definitions
 483   When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
 484
 485 * Token definitions as enums
 486   Tokens are output both as the traditional #define's, and, provided
 487   the compiler supports ANSI C or is a C++ compiler, as enums.
 488   This lets debuggers display names instead of integers.
 489
 490 * Reports
 491   In addition to --verbose, bison supports --report=THINGS, which
 492   produces additional information:
 493   - itemset
 494     complete the core item sets with their closure
 495   - lookahead [changed to `look-ahead' in 1.875e through 2.3, but changed back]
 496     explicitly associate lookahead tokens to items
 497   - solved
 498     describe shift/reduce conflicts solving.
 499     Bison used to systematically output this information on top of
 500     the report.  Solved conflicts are now attached to their states.
 501
 502 * Type clashes
 503   Previous versions don't complain when there is a type clash on
 504   the default action if the rule has a mid-rule action, such as in:
 505
 506       %type <foo> bar
 507       %%
 508       bar: '0' {} '0';
 509
 510   This is fixed.
 511
 512 * GNU M4 is now required when using Bison.
 513 \f
 514 Changes in version 1.35, 2002-03-25:
 515
 516 * C Skeleton
 517   Some projects use Bison's C parser with C++ compilers, and define
 518   YYSTYPE as a class.  The recent adjustment of C parsers for data
 519   alignment and 64 bit architectures made this impossible.
 520
 521   Because for the time being no real solution for C++ parser
 522   generation exists, kludges were implemented in the parser to
 523   maintain this use.  In the future, when Bison has C++ parsers, this
 524   kludge will be disabled.
 525
 526   This kludge also addresses some C++ problems when the stack was
 527   extended.
 528 \f
 529 Changes in version 1.34, 2002-03-12:
 530
 531 * File name clashes are detected
 532   $ bison foo.y -d -o foo.x
 533   fatal error: header and parser would both be named `foo.x'
 534
 535 * A missing `;' at the end of a rule triggers a warning
 536   In accordance with POSIX, and in agreement with other
 537   Yacc implementations, Bison will mandate this semicolon in the near
 538   future.  This eases the implementation of a Bison parser of Bison
 539   grammars by making this grammar LALR(1) instead of LR(2).  To
 540   facilitate the transition, this release introduces a warning.
 541
 542 * Revert the C++ namespace changes introduced in 1.31, as they caused too
 543   many portability hassles.
 544
 545 * DJGPP support added.
 546
 547 * Fix test suite portability problems.
 548 \f
 549 Changes in version 1.33, 2002-02-07:
 550
 551 * Fix C++ issues
 552   Groff could not be compiled for the definition of size_t was lacking
 553   under some conditions.
 554
 555 * Catch invalid @n
 556   As is done with $n.
 557 \f
 558 Changes in version 1.32, 2002-01-23:
 559
 560 * Fix Yacc output file names
 561
 562 * Portability fixes
 563
 564 * Italian, Dutch translations
 565 \f
 566 Changes in version 1.31, 2002-01-14:
 567
 568 * Many Bug Fixes
 569
 570 * GNU Gettext and %expect
 571   GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
 572   Bison dies on incorrect %expectations, we fear there will be
 573   too many bug reports for Gettext, so _for the time being_, %expect
 574   does not trigger an error when the input file is named `plural.y'.
 575
 576 * Use of alloca in parsers
 577   If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
 578   malloc exclusively.  Since 1.29, but was not NEWS'ed.
 579
 580   alloca is used only when compiled with GCC, to avoid portability
 581   problems as on AIX.
 582
 583 * yyparse now returns 2 if memory is exhausted; formerly it dumped core.
 584
 585 * When the generated parser lacks debugging code, YYDEBUG is now 0
 586   (as POSIX requires) instead of being undefined.
 587
 588 * User Actions
 589   Bison has always permitted actions such as { $$ = $1 }: it adds the
 590   ending semicolon.  Now if in Yacc compatibility mode, the semicolon
 591   is no longer output: one has to write { $$ = $1; }.
 592
 593 * Better C++ compliance
 594   The output parsers try to respect C++ namespaces.
 595   [This turned out to be a failed experiment, and it was reverted later.]
 596
 597 * Reduced Grammars
 598   Fixed bugs when reporting useless nonterminals.
 599
 600 * 64 bit hosts
 601   The parsers work properly on 64 bit hosts.
 602
 603 * Error messages
 604   Some calls to strerror resulted in scrambled or missing error messages.
 605
 606 * %expect
 607   When the number of shift/reduce conflicts is correct, don't issue
 608   any warning.
 609
 610 * The verbose report includes the rule line numbers.
 611
 612 * Rule line numbers are fixed in traces.
 613
 614 * Swedish translation
 615
 616 * Parse errors
 617   Verbose parse error messages from the parsers are better looking.
 618   Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
 619      Now: parse error: unexpected '/', expecting "number" or '-' or '('
 620
 621 * Fixed parser memory leaks.
 622   When the generated parser was using malloc to extend its stacks, the
 623   previous allocations were not freed.
 624
 625 * Fixed verbose output file.
 626   Some newlines were missing.
 627   Some conflicts in state descriptions were missing.
 628
 629 * Fixed conflict report.
 630   Option -v was needed to get the result.
 631
 632 * %expect
 633   Was not used.
 634   Mismatches are errors, not warnings.
 635
 636 * Fixed incorrect processing of some invalid input.
 637
 638 * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
 639
 640 * Fixed some typos in the documentation.
 641
 642 * %token MY_EOF 0 is supported.
 643   Before, MY_EOF was silently renumbered as 257.
 644
 645 * doc/refcard.tex is updated.
 646
 647 * %output, %file-prefix, %name-prefix.
 648   New.
 649
 650 * --output
 651   New, aliasing `--output-file'.
 652 \f
 653 Changes in version 1.30, 2001-10-26:
 654
 655 * `--defines' and `--graph' have now an optional argument which is the
 656   output file name. `-d' and `-g' do not change; they do not take any
 657   argument.
 658
 659 * `%source_extension' and `%header_extension' are removed, failed
 660   experiment.
 661
 662 * Portability fixes.
 663 \f
 664 Changes in version 1.29, 2001-09-07:
 665
 666 * The output file does not define const, as this caused problems when used
 667   with common autoconfiguration schemes.  If you still use ancient compilers
 668   that lack const, compile with the equivalent of the C compiler option
 669   `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
 670
 671 * Added `-g' and `--graph'.
 672
 673 * The Bison manual is now distributed under the terms of the GNU FDL.
 674
 675 * The input and the output files has automatically a similar extension.
 676
 677 * Russian translation added.
 678
 679 * NLS support updated; should hopefully be less troublesome.
 680
 681 * Added the old Bison reference card.
 682
 683 * Added `--locations' and `%locations'.
 684
 685 * Added `-S' and `--skeleton'.
 686
 687 * `%raw', `-r', `--raw' is disabled.
 688
 689 * Special characters are escaped when output.  This solves the problems
 690   of the #line lines with path names including backslashes.
 691
 692 * New directives.
 693   `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
 694   `%debug', `%source_extension' and `%header_extension'.
 695
 696 * @$
 697   Automatic location tracking.
 698 \f
 699 Changes in version 1.28, 1999-07-06:
 700
 701 * Should compile better now with K&R compilers.
 702
 703 * Added NLS.
 704
 705 * Fixed a problem with escaping the double quote character.
 706
 707 * There is now a FAQ.
 708 \f
 709 Changes in version 1.27:
 710
 711 * The make rule which prevented bison.simple from being created on
 712   some systems has been fixed.
 713 \f
 714 Changes in version 1.26:
 715
 716 * Bison now uses automake.
 717
 718 * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
 719
 720 * Token numbers now start at 257 as previously documented, not 258.
 721
 722 * Bison honors the TMPDIR environment variable.
 723
 724 * A couple of buffer overruns have been fixed.
 725
 726 * Problems when closing files should now be reported.
 727
 728 * Generated parsers should now work even on operating systems which do
 729   not provide alloca().
 730 \f
 731 Changes in version 1.25, 1995-10-16:
 732
 733 * Errors in the input grammar are not fatal; Bison keeps reading
 734 the grammar file, and reports all the errors found in it.
 735
 736 * Tokens can now be specified as multiple-character strings: for
 737 example, you could use "<=" for a token which looks like <=, instead
 738 of chosing a name like LESSEQ.
 739
 740 * The %token_table declaration says to write a table of tokens (names
 741 and numbers) into the parser file.  The yylex function can use this
 742 table to recognize multiple-character string tokens, or for other
 743 purposes.
 744
 745 * The %no_lines declaration says not to generate any #line preprocessor
 746 directives in the parser file.
 747
 748 * The %raw declaration says to use internal Bison token numbers, not
 749 Yacc-compatible token numbers, when token names are defined as macros.
 750
 751 * The --no-parser option produces the parser tables without including
 752 the parser engine; a project can now use its own parser engine.
 753 The actions go into a separate file called NAME.act, in the form of
 754 a switch statement body.
 755 \f
 756 Changes in version 1.23:
 757
 758 The user can define YYPARSE_PARAM as the name of an argument to be
 759 passed into yyparse.  The argument should have type void *.  It should
 760 actually point to an object.  Grammar actions can access the variable
 761 by casting it to the proper pointer type.
 762
 763 Line numbers in output file corrected.
 764 \f
 765 Changes in version 1.22:
 766
 767 --help option added.
 768 \f
 769 Changes in version 1.20:
 770
 771 Output file does not redefine const for C++.
 772
 773 Local Variables:
 774 mode: outline
 775 End:
 776
 777 -----
 778
 779 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
 780 2004, 2005, 2006 Free Software Foundation, Inc.
 781
 782 This file is part of Bison, the GNU Compiler Compiler.
 783
 784 Bison is free software; you can redistribute it and/or modify
 785 it under the terms of the GNU General Public License as published by
 786 the Free Software Foundation; either version 2, or (at your option)
 787 any later version.
 788
 789 Bison is distributed in the hope that it will be useful,
 790 but WITHOUT ANY WARRANTY; without even the implied warranty of
 791 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 792 GNU General Public License for more details.
 793
 794 You should have received a copy of the GNU General Public License
 795 along with autoconf; see the file COPYING.  If not, write to
 796 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 797 Boston, MA 02110-1301, USA.