NEWS

   1 Bison News
   2 ----------
   3
   4 Changes in version 2.3+:
   5
   6 * Locations columns and lines start at 1.
   7   In accordance with the GNU Coding Standards and Emacs.
   8
   9 * Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
  10   `--yacc', or `%yacc'), Bison no longer generates #define statements for
  11   associating token numbers with token names.  Removing the #define statements
  12   helps to sanitize the global namespace during preprocessing, but POSIX Yacc
  13   requires them.  Bison still generates an enum for token names in all cases.
  14
  15 * Handling of traditional Yacc prologue blocks is now more consistent but
  16   potentially incompatible with previous releases of Bison.
  17
  18   As before, you declare prologue blocks in your grammar file with the
  19   `%{ ... %}' syntax.  To generate the pre-prologue, Bison concatenates all
  20   prologue blocks that you've declared before the first %union.  To generate
  21   the post-prologue, Bison concatenates all prologue blocks that you've
  22   declared after the first %union.
  23
  24   Previous releases of Bison inserted the pre-prologue into both the header
  25   file and the code file in all cases except for LALR(1) parsers in C.  In the
  26   latter case, Bison inserted it only into the code file.  For parsers in C++,
  27   the point of insertion was before any token definitions (which associate
  28   token numbers with names).  For parsers in C, the point of insertion was
  29   after the token definitions.
  30
  31   Now, Bison never inserts the pre-prologue into the header file.  In the code
  32   file, it always inserts it before the token definitions.
  33
  34 * Bison now provides a more flexible alternative to the traditional Yacc
  35   prologue blocks: %before-header, %start-header, %end-header, and
  36   %after-header.
  37
  38   For example, the following declaration order in the grammar file reflects the
  39   order in which Bison will output these code blocks.  However, you are free to
  40   declare these code blocks in your grammar file in whatever order is most
  41   convenient for you:
  42
  43     %before-header {
  44       /* Bison treats this block like a pre-prologue block: it inserts it into
  45        * the code file before the contents of the header file.  It does *not*
  46        * insert it into the header file.  This is a good place to put
  47        * #include's that you want at the top of your code file.  A common
  48        * example is `#include "system.h"'.  */
  49     }
  50     %start-header {
  51       /* Bison inserts this block into both the header file and the code file.
  52        * In both files, the point of insertion is before any Bison-generated
  53        * token, semantic type, location type, and class definitions.  This is a
  54        * good place to define %union dependencies, for example.  */
  55     }
  56     %union {
  57       /* Unlike the traditional Yacc prologue blocks, the output order for the
  58        * new %*-header blocks is not affected by their declaration position
  59        * relative to any %union in the grammar file.  */
  60     }
  61     %end-header {
  62       /* Bison inserts this block into both the header file and the code file.
  63        * In both files, the point of insertion is after the Bison-generated
  64        * definitions.  This is a good place to declare or define public
  65        * functions or data structures that depend on the Bison-generated
  66        * definitions.  */
  67     }
  68     %after-header {
  69       /* Bison treats this block like a post-prologue block: it inserts it into
  70        * the code file after the contents of the header file.  It does *not*
  71        * insert it into the header file.  This is a good place to declare or
  72        * define internal functions or data structures that depend on the
  73        * Bison-generated definitions.  */
  74     }
  75
  76   If you have multiple occurrences of any one of the above declarations, Bison
  77   will concatenate the contents in declaration order.
  78
  79 * The option `--report=look-ahead' has been changed to `--report=lookahead'.
  80   The old spelling still works, but is not documented and may be removed
  81   in a future release.
  82
  83 Changes in version 2.3, 2006-06-05:
  84
  85 * GLR grammars should now use `YYRECOVERING ()' instead of `YYRECOVERING',
  86   for compatibility with LALR(1) grammars.
  87
  88 * It is now documented that any definition of YYSTYPE or YYLTYPE should
  89   be to a type name that does not contain parentheses or brackets.
  90
  91 Changes in version 2.2, 2006-05-19:
  92
  93 * The distribution terms for all Bison-generated parsers now permit
  94   using the parsers in nonfree programs.  Previously, this permission
  95   was granted only for Bison-generated LALR(1) parsers in C.
  96
  97 * %name-prefix changes the namespace name in C++ outputs.
  98
  99 * The C++ parsers export their token_type.
 100
 101 * Bison now allows multiple %union declarations, and concatenates
 102   their contents together.
 103
 104 * New warning: unused values
 105   Right-hand side symbols whose values are not used are reported,
 106   if the symbols have destructors.  For instance:
 107
 108      exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
 109         | exp "+" exp
 110         ;
 111
 112   will trigger a warning about $$ and $5 in the first rule, and $3 in
 113   the second ($1 is copied to $$ by the default rule).  This example
 114   most likely contains three errors, and could be rewritten as:
 115
 116      exp: exp "?" exp ":" exp
 117             { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
 118         | exp "+" exp
 119             { $$ = $1 ? $1 : $3; if ($1) free ($3); }
 120         ;
 121
 122   However, if the original actions were really intended, memory leaks
 123   and all, the warnings can be suppressed by letting Bison believe the
 124   values are used, e.g.:
 125
 126      exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
 127         | exp "+" exp         { $$ = $1; (void) $3; }
 128         ;
 129
 130   If there are mid-rule actions, the warning is issued if no action
 131   uses it.  The following triggers no warning: $1 and $3 are used.
 132
 133      exp: exp { push ($1); } '+' exp { push ($3); sum (); };
 134
 135   The warning is intended to help catching lost values and memory leaks.
 136   If a value is ignored, its associated memory typically is not reclaimed.
 137
 138 * %destructor vs. YYABORT, YYACCEPT, and YYERROR.
 139   Destructors are now called when user code invokes YYABORT, YYACCEPT,
 140   and YYERROR, for all objects on the stack, other than objects
 141   corresponding to the right-hand side of the current rule.
 142
 143 * %expect, %expect-rr
 144   Incorrect numbers of expected conflicts are now actual errors,
 145   instead of warnings.
 146
 147 * GLR, YACC parsers.
 148   The %parse-params are available in the destructors (and the
 149   experimental printers) as per the documentation.
 150
 151 * Bison now warns if it finds a stray `$' or `@' in an action.
 152
 153 * %require "VERSION"
 154   This specifies that the grammar file depends on features implemented
 155   in Bison version VERSION or higher.
 156
 157 * lalr1.cc: The token and value types are now class members.
 158   The tokens were defined as free form enums and cpp macros.  YYSTYPE
 159   was defined as a free form union.  They are now class members:
 160   tokens are enumerations of the `yy::parser::token' struct, and the
 161   semantic values have the `yy::parser::semantic_type' type.
 162
 163   If you do not want or can update to this scheme, the directive
 164   `%define "global_tokens_and_yystype" "1"' triggers the global
 165   definition of tokens and YYSTYPE.  This change is suitable both
 166   for previous releases of Bison, and this one.
 167
 168   If you wish to update, then make sure older version of Bison will
 169   fail using `%require "2.2"'.
 170
 171 * DJGPP support added.
 172 \f
 173 Changes in version 2.1, 2005-09-16:
 174
 175 * The C++ lalr1.cc skeleton supports %lex-param.
 176
 177 * Bison-generated parsers now support the translation of diagnostics like
 178   "syntax error" into languages other than English.  The default
 179   language is still English.  For details, please see the new
 180   Internationalization section of the Bison manual.  Software
 181   distributors should also see the new PACKAGING file.  Thanks to
 182   Bruno Haible for this new feature.
 183
 184 * Wording in the Bison-generated parsers has been changed slightly to
 185   simplify translation.  In particular, the message "memory exhausted"
 186   has replaced "parser stack overflow", as the old message was not
 187   always accurate for modern Bison-generated parsers.
 188
 189 * Destructors are now called when the parser aborts, for all symbols left
 190   behind on the stack.  Also, the start symbol is now destroyed after a
 191   successful parse.  In both cases, the behavior was formerly inconsistent.
 192
 193 * When generating verbose diagnostics, Bison-generated parsers no longer
 194   quote the literal strings associated with tokens.  For example, for
 195   a syntax error associated with '%token NUM "number"' they might
 196   print 'syntax error, unexpected number' instead of 'syntax error,
 197   unexpected "number"'.
 198 \f
 199 Changes in version 2.0, 2004-12-25:
 200
 201 * Possibly-incompatible changes
 202
 203   - Bison-generated parsers no longer default to using the alloca function
 204     (when available) to extend the parser stack, due to widespread
 205     problems in unchecked stack-overflow detection.  You can "#define
 206     YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read
 207     the manual to determine safe values for YYMAXDEPTH in that case.
 208
 209   - Error token location.
 210     During error recovery, the location of the syntax error is updated
 211     to cover the whole sequence covered by the error token: it includes
 212     the shifted symbols thrown away during the first part of the error
 213     recovery, and the lookahead rejected during the second part.
 214
 215   - Semicolon changes:
 216     . Stray semicolons are no longer allowed at the start of a grammar.
 217     . Semicolons are now required after in-grammar declarations.
 218
 219   - Unescaped newlines are no longer allowed in character constants or
 220     string literals.  They were never portable, and GCC 3.4.0 has
 221     dropped support for them.  Better diagnostics are now generated if
 222     forget a closing quote.
 223
 224   - NUL bytes are no longer allowed in Bison string literals, unfortunately.
 225
 226 * New features
 227
 228   - GLR grammars now support locations.
 229
 230   - New directive: %initial-action.
 231     This directive allows the user to run arbitrary code (including
 232     initializing @$) from yyparse before parsing starts.
 233
 234   - A new directive "%expect-rr N" specifies the expected number of
 235     reduce/reduce conflicts in GLR parsers.
 236
 237   - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
 238     This is a GNU extension.
 239
 240   - The option `--report=lookahead' was changed to `--report=look-ahead'.
 241     [However, this was changed back after 2.3.]
 242
 243   - Experimental %destructor support has been added to lalr1.cc.
 244
 245   - New configure option --disable-yacc, to disable installation of the
 246     yacc command and -ly library introduced in 1.875 for POSIX conformance.
 247
 248 * Bug fixes
 249
 250   - For now, %expect-count violations are now just warnings, not errors.
 251     This is for compatibility with Bison 1.75 and earlier (when there are
 252     reduce/reduce conflicts) and with Bison 1.30 and earlier (when there
 253     are too many or too few shift/reduce conflicts).  However, in future
 254     versions of Bison we plan to improve the %expect machinery so that
 255     these violations will become errors again.
 256
 257   - Within Bison itself, numbers (e.g., goto numbers) are no longer
 258     arbitrarily limited to 16-bit counts.
 259
 260   - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.
 261 \f
 262 Changes in version 1.875, 2003-01-01:
 263
 264 * The documentation license has been upgraded to version 1.2
 265   of the GNU Free Documentation License.
 266
 267 * syntax error processing
 268
 269   - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
 270     locations too.  This fixes bugs in error-location computation.
 271
 272   - %destructor
 273     It is now possible to reclaim the memory associated to symbols
 274     discarded during error recovery.  This feature is still experimental.
 275
 276   - %error-verbose
 277     This new directive is preferred over YYERROR_VERBOSE.
 278
 279   - #defining yyerror to steal internal variables is discouraged.
 280     It is not guaranteed to work forever.
 281
 282 * POSIX conformance
 283
 284   - Semicolons are once again optional at the end of grammar rules.
 285     This reverts to the behavior of Bison 1.33 and earlier, and improves
 286     compatibility with Yacc.
 287
 288   - `parse error' -> `syntax error'
 289     Bison now uniformly uses the term `syntax error'; formerly, the code
 290     and manual sometimes used the term `parse error' instead.  POSIX
 291     requires `syntax error' in diagnostics, and it was thought better to
 292     be consistent.
 293
 294   - The documentation now emphasizes that yylex and yyerror must be
 295     declared before use.  C99 requires this.
 296
 297   - Bison now parses C99 lexical constructs like UCNs and
 298     backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
 299
 300   - File names are properly escaped in C output.  E.g., foo\bar.y is
 301     output as "foo\\bar.y".
 302
 303   - Yacc command and library now available
 304     The Bison distribution now installs a `yacc' command, as POSIX requires.
 305     Also, Bison now installs a small library liby.a containing
 306     implementations of Yacc-compatible yyerror and main functions.
 307     This library is normally not useful, but POSIX requires it.
 308
 309   - Type clashes now generate warnings, not errors.
 310
 311   - If the user does not define YYSTYPE as a macro, Bison now declares it
 312     using typedef instead of defining it as a macro.
 313     For consistency, YYLTYPE is also declared instead of defined.
 314
 315 * Other compatibility issues
 316
 317   - %union directives can now have a tag before the `{', e.g., the
 318     directive `%union foo {...}' now generates the C code
 319     `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
 320     The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
 321     For consistency, YYLTYPE's struct tag is now `YYLTYPE' not `yyltype'.
 322     This is for compatibility with both Yacc and Bison 1.35.
 323
 324   - `;' is output before the terminating `}' of an action, for
 325     compatibility with Bison 1.35.
 326
 327   - Bison now uses a Yacc-style format for conflict reports, e.g.,
 328     `conflicts: 2 shift/reduce, 1 reduce/reduce'.
 329
 330   - `yystype' and `yyltype' are now obsolescent macros instead of being
 331     typedefs or tags; they are no longer documented and are planned to be
 332     withdrawn in a future release.
 333
 334 * GLR parser notes
 335
 336   - GLR and inline
 337     Users of Bison have to decide how they handle the portability of the
 338     C keyword `inline'.
 339
 340   - `parsing stack overflow...' -> `parser stack overflow'
 341     GLR parsers now report `parser stack overflow' as per the Bison manual.
 342
 343 * Bison now warns if it detects conflicting outputs to the same file,
 344   e.g., it generates a warning for `bison -d -o foo.h foo.y' since
 345   that command outputs both code and header to foo.h.
 346
 347 * #line in output files
 348   - --no-line works properly.
 349
 350 * Bison can no longer be built by a K&R C compiler; it requires C89 or
 351   later to be built.  This change originally took place a few versions
 352   ago, but nobody noticed until we recently asked someone to try
 353   building Bison with a K&R C compiler.
 354 \f
 355 Changes in version 1.75, 2002-10-14:
 356
 357 * Bison should now work on 64-bit hosts.
 358
 359 * Indonesian translation thanks to Tedi Heriyanto.
 360
 361 * GLR parsers
 362   Fix spurious parse errors.
 363
 364 * Pure parsers
 365   Some people redefine yyerror to steal yyparse' private variables.
 366   Reenable this trick until an official feature replaces it.
 367
 368 * Type Clashes
 369   In agreement with POSIX and with other Yaccs, leaving a default
 370   action is valid when $$ is untyped, and $1 typed:
 371
 372         untyped: ... typed;
 373
 374   but the converse remains an error:
 375
 376         typed: ... untyped;
 377
 378 * Values of mid-rule actions
 379   The following code:
 380
 381         foo: { ... } { $$ = $1; } ...
 382
 383   was incorrectly rejected: $1 is defined in the second mid-rule
 384   action, and is equal to the $$ of the first mid-rule action.
 385 \f
 386 Changes in version 1.50, 2002-10-04:
 387
 388 * GLR parsing
 389   The declaration
 390      %glr-parser
 391   causes Bison to produce a Generalized LR (GLR) parser, capable of handling
 392   almost any context-free grammar, ambiguous or not.  The new declarations
 393   %dprec and %merge on grammar rules allow parse-time resolution of
 394   ambiguities.  Contributed by Paul Hilfinger.
 395
 396   Unfortunately Bison 1.50 does not work properly on 64-bit hosts
 397   like the Alpha, so please stick to 32-bit hosts for now.
 398
 399 * Output Directory
 400   When not in Yacc compatibility mode, when the output file was not
 401   specified, running `bison foo/bar.y' created `foo/bar.c'.  It
 402   now creates `bar.c'.
 403
 404 * Undefined token
 405   The undefined token was systematically mapped to 2 which prevented
 406   the use of 2 by the user.  This is no longer the case.
 407
 408 * Unknown token numbers
 409   If yylex returned an out of range value, yyparse could die.  This is
 410   no longer the case.
 411
 412 * Error token
 413   According to POSIX, the error token must be 256.
 414   Bison extends this requirement by making it a preference: *if* the
 415   user specified that one of her tokens is numbered 256, then error
 416   will be mapped onto another number.
 417
 418 * Verbose error messages
 419   They no longer report `..., expecting error or...' for states where
 420   error recovery is possible.
 421
 422 * End token
 423   Defaults to `$end' instead of `$'.
 424
 425 * Error recovery now conforms to documentation and to POSIX
 426   When a Bison-generated parser encounters a syntax error, it now pops
 427   the stack until it finds a state that allows shifting the error
 428   token.  Formerly, it popped the stack until it found a state that
 429   allowed some non-error action other than a default reduction on the
 430   error token.  The new behavior has long been the documented behavior,
 431   and has long been required by POSIX.  For more details, please see
 432   Paul Eggert, "Reductions during Bison error handling" (2002-05-20)
 433   <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>.
 434
 435 * Traces
 436   Popped tokens and nonterminals are now reported.
 437
 438 * Larger grammars
 439   Larger grammars are now supported (larger token numbers, larger grammar
 440   size (= sum of the LHS and RHS lengths), larger LALR tables).
 441   Formerly, many of these numbers ran afoul of 16-bit limits;
 442   now these limits are 32 bits on most hosts.
 443
 444 * Explicit initial rule
 445   Bison used to play hacks with the initial rule, which the user does
 446   not write.  It is now explicit, and visible in the reports and
 447   graphs as rule 0.
 448
 449 * Useless rules
 450   Before, Bison reported the useless rules, but, although not used,
 451   included them in the parsers.  They are now actually removed.
 452
 453 * Useless rules, useless nonterminals
 454   They are now reported, as a warning, with their locations.
 455
 456 * Rules never reduced
 457   Rules that can never be reduced because of conflicts are now
 458   reported.
 459
 460 * Incorrect `Token not used'
 461   On a grammar such as
 462
 463            %token useless useful
 464            %%
 465            exp: '0' %prec useful;
 466
 467   where a token was used to set the precedence of the last rule,
 468   bison reported both `useful' and `useless' as useless tokens.
 469
 470 * Revert the C++ namespace changes introduced in 1.31
 471   as they caused too many portability hassles.
 472
 473 * Default locations
 474   By an accident of design, the default computation of @$ was
 475   performed after another default computation was performed: @$ = @1.
 476   The latter is now removed: YYLLOC_DEFAULT is fully responsible of
 477   the computation of @$.
 478
 479 * Token end-of-file
 480   The token end of file may be specified by the user, in which case,
 481   the user symbol is used in the reports, the graphs, and the verbose
 482   error messages instead of `$end', which remains being the default.
 483   For instance
 484      %token MYEOF 0
 485   or
 486      %token MYEOF 0 "end of file"
 487
 488 * Semantic parser
 489   This old option, which has been broken for ages, is removed.
 490
 491 * New translations
 492   Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
 493   Croatian, thanks to Denis Lackovic.
 494
 495 * Incorrect token definitions
 496   When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
 497
 498 * Token definitions as enums
 499   Tokens are output both as the traditional #define's, and, provided
 500   the compiler supports ANSI C or is a C++ compiler, as enums.
 501   This lets debuggers display names instead of integers.
 502
 503 * Reports
 504   In addition to --verbose, bison supports --report=THINGS, which
 505   produces additional information:
 506   - itemset
 507     complete the core item sets with their closure
 508   - lookahead [changed to `look-ahead' in 1.875e through 2.3, but changed back]
 509     explicitly associate lookahead tokens to items
 510   - solved
 511     describe shift/reduce conflicts solving.
 512     Bison used to systematically output this information on top of
 513     the report.  Solved conflicts are now attached to their states.
 514
 515 * Type clashes
 516   Previous versions don't complain when there is a type clash on
 517   the default action if the rule has a mid-rule action, such as in:
 518
 519       %type <foo> bar
 520       %%
 521       bar: '0' {} '0';
 522
 523   This is fixed.
 524
 525 * GNU M4 is now required when using Bison.
 526 \f
 527 Changes in version 1.35, 2002-03-25:
 528
 529 * C Skeleton
 530   Some projects use Bison's C parser with C++ compilers, and define
 531   YYSTYPE as a class.  The recent adjustment of C parsers for data
 532   alignment and 64 bit architectures made this impossible.
 533
 534   Because for the time being no real solution for C++ parser
 535   generation exists, kludges were implemented in the parser to
 536   maintain this use.  In the future, when Bison has C++ parsers, this
 537   kludge will be disabled.
 538
 539   This kludge also addresses some C++ problems when the stack was
 540   extended.
 541 \f
 542 Changes in version 1.34, 2002-03-12:
 543
 544 * File name clashes are detected
 545   $ bison foo.y -d -o foo.x
 546   fatal error: header and parser would both be named `foo.x'
 547
 548 * A missing `;' at the end of a rule triggers a warning
 549   In accordance with POSIX, and in agreement with other
 550   Yacc implementations, Bison will mandate this semicolon in the near
 551   future.  This eases the implementation of a Bison parser of Bison
 552   grammars by making this grammar LALR(1) instead of LR(2).  To
 553   facilitate the transition, this release introduces a warning.
 554
 555 * Revert the C++ namespace changes introduced in 1.31, as they caused too
 556   many portability hassles.
 557
 558 * DJGPP support added.
 559
 560 * Fix test suite portability problems.
 561 \f
 562 Changes in version 1.33, 2002-02-07:
 563
 564 * Fix C++ issues
 565   Groff could not be compiled for the definition of size_t was lacking
 566   under some conditions.
 567
 568 * Catch invalid @n
 569   As is done with $n.
 570 \f
 571 Changes in version 1.32, 2002-01-23:
 572
 573 * Fix Yacc output file names
 574
 575 * Portability fixes
 576
 577 * Italian, Dutch translations
 578 \f
 579 Changes in version 1.31, 2002-01-14:
 580
 581 * Many Bug Fixes
 582
 583 * GNU Gettext and %expect
 584   GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
 585   Bison dies on incorrect %expectations, we fear there will be
 586   too many bug reports for Gettext, so _for the time being_, %expect
 587   does not trigger an error when the input file is named `plural.y'.
 588
 589 * Use of alloca in parsers
 590   If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
 591   malloc exclusively.  Since 1.29, but was not NEWS'ed.
 592
 593   alloca is used only when compiled with GCC, to avoid portability
 594   problems as on AIX.
 595
 596 * yyparse now returns 2 if memory is exhausted; formerly it dumped core.
 597
 598 * When the generated parser lacks debugging code, YYDEBUG is now 0
 599   (as POSIX requires) instead of being undefined.
 600
 601 * User Actions
 602   Bison has always permitted actions such as { $$ = $1 }: it adds the
 603   ending semicolon.  Now if in Yacc compatibility mode, the semicolon
 604   is no longer output: one has to write { $$ = $1; }.
 605
 606 * Better C++ compliance
 607   The output parsers try to respect C++ namespaces.
 608   [This turned out to be a failed experiment, and it was reverted later.]
 609
 610 * Reduced Grammars
 611   Fixed bugs when reporting useless nonterminals.
 612
 613 * 64 bit hosts
 614   The parsers work properly on 64 bit hosts.
 615
 616 * Error messages
 617   Some calls to strerror resulted in scrambled or missing error messages.
 618
 619 * %expect
 620   When the number of shift/reduce conflicts is correct, don't issue
 621   any warning.
 622
 623 * The verbose report includes the rule line numbers.
 624
 625 * Rule line numbers are fixed in traces.
 626
 627 * Swedish translation
 628
 629 * Parse errors
 630   Verbose parse error messages from the parsers are better looking.
 631   Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
 632      Now: parse error: unexpected '/', expecting "number" or '-' or '('
 633
 634 * Fixed parser memory leaks.
 635   When the generated parser was using malloc to extend its stacks, the
 636   previous allocations were not freed.
 637
 638 * Fixed verbose output file.
 639   Some newlines were missing.
 640   Some conflicts in state descriptions were missing.
 641
 642 * Fixed conflict report.
 643   Option -v was needed to get the result.
 644
 645 * %expect
 646   Was not used.
 647   Mismatches are errors, not warnings.
 648
 649 * Fixed incorrect processing of some invalid input.
 650
 651 * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
 652
 653 * Fixed some typos in the documentation.
 654
 655 * %token MY_EOF 0 is supported.
 656   Before, MY_EOF was silently renumbered as 257.
 657
 658 * doc/refcard.tex is updated.
 659
 660 * %output, %file-prefix, %name-prefix.
 661   New.
 662
 663 * --output
 664   New, aliasing `--output-file'.
 665 \f
 666 Changes in version 1.30, 2001-10-26:
 667
 668 * `--defines' and `--graph' have now an optional argument which is the
 669   output file name. `-d' and `-g' do not change; they do not take any
 670   argument.
 671
 672 * `%source_extension' and `%header_extension' are removed, failed
 673   experiment.
 674
 675 * Portability fixes.
 676 \f
 677 Changes in version 1.29, 2001-09-07:
 678
 679 * The output file does not define const, as this caused problems when used
 680   with common autoconfiguration schemes.  If you still use ancient compilers
 681   that lack const, compile with the equivalent of the C compiler option
 682   `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
 683
 684 * Added `-g' and `--graph'.
 685
 686 * The Bison manual is now distributed under the terms of the GNU FDL.
 687
 688 * The input and the output files has automatically a similar extension.
 689
 690 * Russian translation added.
 691
 692 * NLS support updated; should hopefully be less troublesome.
 693
 694 * Added the old Bison reference card.
 695
 696 * Added `--locations' and `%locations'.
 697
 698 * Added `-S' and `--skeleton'.
 699
 700 * `%raw', `-r', `--raw' is disabled.
 701
 702 * Special characters are escaped when output.  This solves the problems
 703   of the #line lines with path names including backslashes.
 704
 705 * New directives.
 706   `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
 707   `%debug', `%source_extension' and `%header_extension'.
 708
 709 * @$
 710   Automatic location tracking.
 711 \f
 712 Changes in version 1.28, 1999-07-06:
 713
 714 * Should compile better now with K&R compilers.
 715
 716 * Added NLS.
 717
 718 * Fixed a problem with escaping the double quote character.
 719
 720 * There is now a FAQ.
 721 \f
 722 Changes in version 1.27:
 723
 724 * The make rule which prevented bison.simple from being created on
 725   some systems has been fixed.
 726 \f
 727 Changes in version 1.26:
 728
 729 * Bison now uses automake.
 730
 731 * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
 732
 733 * Token numbers now start at 257 as previously documented, not 258.
 734
 735 * Bison honors the TMPDIR environment variable.
 736
 737 * A couple of buffer overruns have been fixed.
 738
 739 * Problems when closing files should now be reported.
 740
 741 * Generated parsers should now work even on operating systems which do
 742   not provide alloca().
 743 \f
 744 Changes in version 1.25, 1995-10-16:
 745
 746 * Errors in the input grammar are not fatal; Bison keeps reading
 747 the grammar file, and reports all the errors found in it.
 748
 749 * Tokens can now be specified as multiple-character strings: for
 750 example, you could use "<=" for a token which looks like <=, instead
 751 of chosing a name like LESSEQ.
 752
 753 * The %token_table declaration says to write a table of tokens (names
 754 and numbers) into the parser file.  The yylex function can use this
 755 table to recognize multiple-character string tokens, or for other
 756 purposes.
 757
 758 * The %no_lines declaration says not to generate any #line preprocessor
 759 directives in the parser file.
 760
 761 * The %raw declaration says to use internal Bison token numbers, not
 762 Yacc-compatible token numbers, when token names are defined as macros.
 763
 764 * The --no-parser option produces the parser tables without including
 765 the parser engine; a project can now use its own parser engine.
 766 The actions go into a separate file called NAME.act, in the form of
 767 a switch statement body.
 768 \f
 769 Changes in version 1.23:
 770
 771 The user can define YYPARSE_PARAM as the name of an argument to be
 772 passed into yyparse.  The argument should have type void *.  It should
 773 actually point to an object.  Grammar actions can access the variable
 774 by casting it to the proper pointer type.
 775
 776 Line numbers in output file corrected.
 777 \f
 778 Changes in version 1.22:
 779
 780 --help option added.
 781 \f
 782 Changes in version 1.20:
 783
 784 Output file does not redefine const for C++.
 785
 786 Local Variables:
 787 mode: outline
 788 End:
 789
 790 -----
 791
 792 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
 793 2004, 2005, 2006 Free Software Foundation, Inc.
 794
 795 This file is part of Bison, the GNU Compiler Compiler.
 796
 797 Bison is free software; you can redistribute it and/or modify
 798 it under the terms of the GNU General Public License as published by
 799 the Free Software Foundation; either version 2, or (at your option)
 800 any later version.
 801
 802 Bison is distributed in the hope that it will be useful,
 803 but WITHOUT ANY WARRANTY; without even the implied warranty of
 804 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 805 GNU General Public License for more details.
 806
 807 You should have received a copy of the GNU General Public License
 808 along with autoconf; see the file COPYING.  If not, write to
 809 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 810 Boston, MA 02110-1301, USA.