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