| 1 | Bison News |
| 2 | ---------- |
| 3 | |
| 4 | Changes in version 1.75f, 2002-12-28: |
| 5 | |
| 6 | * In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error |
| 7 | locations too. This fixes bugs in error-location computation. |
| 8 | |
| 9 | * Bison now uses a Yacc-style format for conflict reports, e.g., |
| 10 | "conflicts: 2 shift/reduce, 1 reduce/reduce". |
| 11 | |
| 12 | * Bison now warns if it detects conflicting outputs to the same file, |
| 13 | e.g., it generates a warning for "bison -d -o foo.h foo.y" since |
| 14 | that command outputs both code and header to foo.h. |
| 15 | |
| 16 | Changes in version 1.75e, 2002-12-24: |
| 17 | |
| 18 | * If the user does not define YYSTYPE as a macro, Bison now declares it |
| 19 | using typedef instead of defining it as a macro. POSIX requires this. |
| 20 | For consistency, YYLTYPE is also declared instead of defined. |
| 21 | |
| 22 | * %union directives can now have a tag before the `{', e.g., the |
| 23 | directive `%union foo {...}' now generates the C code |
| 24 | `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility. |
| 25 | The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc. |
| 26 | For consistency, YYLTYPE's struct tag is now `YYLTYPE' instead of `yyltype'. |
| 27 | |
| 28 | * `yystype' and `yyltype' are now obsolescent macros instead of being |
| 29 | typedefs or tags; they are no longer documented and will be |
| 30 | withdrawn in a future release. |
| 31 | |
| 32 | * References to the experimental %lex-param and %parse-param directives |
| 33 | have been temporarily removed from the manual, since we don't want |
| 34 | users to rely upon these features quite yet. |
| 35 | |
| 36 | Changes in version 1.75d, 2002-12-13: |
| 37 | |
| 38 | * Semicolons are once again optional at the end of grammar rules. |
| 39 | This reverts to the behavior of Bison 1.33 and earlier, and improves |
| 40 | compatibility with Yacc. |
| 41 | |
| 42 | * Type clashes now generate warnings, not errors. |
| 43 | |
| 44 | * Yacc command and library now available |
| 45 | The Bison distribution now installs a yacc command, as POSIX requires. |
| 46 | Also, Bison now installs a small library liby.a containing |
| 47 | implementations of Yacc-compatible yyerror and main functions. |
| 48 | This library is normally not useful, but POSIX requires it. |
| 49 | |
| 50 | * %lex-param, %parse-param |
| 51 | These now take just one operand, not two. |
| 52 | |
| 53 | * The documentation now emphasizes that yylex and yyerror must be |
| 54 | declared before use. C99 requires this. |
| 55 | |
| 56 | * The documentation license has been upgraded to version 1.2 |
| 57 | of the GNU Free Documentation License. |
| 58 | |
| 59 | Changes in version 1.75c, 2002-11-25: |
| 60 | |
| 61 | * "parse error" -> "syntax error" |
| 62 | Bison now uniformly uses the term "syntax error"; formerly, the code |
| 63 | and manual sometimes used the term "parse error" instead. POSIX |
| 64 | requires "syntax error" in diagnostics, and it was thought better to |
| 65 | be consistent. |
| 66 | |
| 67 | * "parsing stack overflow..." -> "parser stack overflow" |
| 68 | GLR parsers now report "parser stack overflow" as per the Bison manual. |
| 69 | |
| 70 | * GLR and inline |
| 71 | Users of Bison have to decide how they handle the portability of the |
| 72 | C keyword `inline'. |
| 73 | |
| 74 | Changes in version 1.75b, 2002-11-13: |
| 75 | |
| 76 | * %destructor |
| 77 | It is now possible to reclaim the memory associated to symbols |
| 78 | discarded during error recovery. This feature is still experimental. |
| 79 | |
| 80 | * Bison now parses C99 lexical constructs like UCNs and |
| 81 | backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires. |
| 82 | |
| 83 | * --no-line works properly. |
| 84 | |
| 85 | * %error-verbose |
| 86 | This new directive is preferred over YYERROR_VERBOSE. |
| 87 | |
| 88 | * %lex-param, %parse-param |
| 89 | These new directives are preferred over PARSE_PARAM and LEX_PARAM. |
| 90 | In addition, they provide a means for yyerror to remain pure, and |
| 91 | to access to the current location. |
| 92 | |
| 93 | #defining yyerror to steal internal variables is strongly |
| 94 | discouraged. It is not guaranteed to work for ever. |
| 95 | |
| 96 | * #line |
| 97 | Bison now recognizes #line in its input, and forwards them. |
| 98 | |
| 99 | * #line |
| 100 | File names are properly escaped. E.g. foo\bar.y give #line 123 "foo\\bar.y". |
| 101 | |
| 102 | Changes in version 1.75a, 2002-10-24: |
| 103 | |
| 104 | * Bison can no longer be built by a K&R C compiler; it requires C89 or |
| 105 | later to be built. This change originally took place a few versions |
| 106 | ago, but nobody noticed until we recently asked someone to try |
| 107 | building Bison with a K&R C compiler. |
| 108 | |
| 109 | Changes in version 1.75, 2002-10-14: |
| 110 | |
| 111 | * Bison should now work on 64-bit hosts. |
| 112 | |
| 113 | * Indonesian translation thanks to Tedi Heriyanto. |
| 114 | |
| 115 | * GLR parsers |
| 116 | Fix spurious parse errors. |
| 117 | |
| 118 | * Pure parsers |
| 119 | Some people redefine yyerror to steal yyparse' private variables. |
| 120 | Reenable this trick until an official feature replaces it. |
| 121 | |
| 122 | * Type Clashes |
| 123 | In agreement with POSIX and with other Yaccs, leaving a default |
| 124 | action is valid when $$ is untyped, and $1 typed: |
| 125 | |
| 126 | untyped: ... typed; |
| 127 | |
| 128 | but the converse remains an error: |
| 129 | |
| 130 | typed: ... untyped; |
| 131 | |
| 132 | * Values of mid-rule actions |
| 133 | The following code: |
| 134 | |
| 135 | foo: { ... } { $$ = $1; } ... |
| 136 | |
| 137 | was incorrectly rejected: $1 is defined in the second mid-rule |
| 138 | action, and is equal to the $$ of the first mid-rule action. |
| 139 | |
| 140 | Changes in version 1.50, 2002-10-04: |
| 141 | |
| 142 | * GLR parsing |
| 143 | The declaration |
| 144 | %glr-parser |
| 145 | causes Bison to produce a Generalized LR (GLR) parser, capable of handling |
| 146 | almost any context-free grammar, ambiguous or not. The new declarations |
| 147 | %dprec and %merge on grammar rules allow parse-time resolution of |
| 148 | ambiguities. Contributed by Paul Hilfinger. |
| 149 | |
| 150 | Unfortunately Bison 1.50 does not work properly on 64-bit hosts |
| 151 | like the Alpha, so please stick to 32-bit hosts for now. |
| 152 | |
| 153 | * Output Directory |
| 154 | When not in Yacc compatibility mode, when the output file was not |
| 155 | specified, running `bison foo/bar.y' created `foo/bar.c'. It |
| 156 | now creates `bar.c'. |
| 157 | |
| 158 | * Undefined token |
| 159 | The undefined token was systematically mapped to 2 which prevented |
| 160 | the use of 2 by the user. This is no longer the case. |
| 161 | |
| 162 | * Unknown token numbers |
| 163 | If yylex returned an out of range value, yyparse could die. This is |
| 164 | no longer the case. |
| 165 | |
| 166 | * Error token |
| 167 | According to POSIX, the error token must be 256. |
| 168 | Bison extends this requirement by making it a preference: *if* the |
| 169 | user specified that one of her tokens is numbered 256, then error |
| 170 | will be mapped onto another number. |
| 171 | |
| 172 | * Verbose error messages |
| 173 | They no longer report `..., expecting error or...' for states where |
| 174 | error recovery is possible. |
| 175 | |
| 176 | * End token |
| 177 | Defaults to `$end' instead of `$'. |
| 178 | |
| 179 | * Error recovery now conforms to documentation and to POSIX |
| 180 | When a Bison-generated parser encounters a syntax error, it now pops |
| 181 | the stack until it finds a state that allows shifting the error |
| 182 | token. Formerly, it popped the stack until it found a state that |
| 183 | allowed some non-error action other than a default reduction on the |
| 184 | error token. The new behavior has long been the documented behavior, |
| 185 | and has long been required by POSIX. For more details, please see |
| 186 | <http://mail.gnu.org/pipermail/bug-bison/2002-May/001452.html>. |
| 187 | |
| 188 | * Traces |
| 189 | Popped tokens and nonterminals are now reported. |
| 190 | |
| 191 | * Larger grammars |
| 192 | Larger grammars are now supported (larger token numbers, larger grammar |
| 193 | size (= sum of the LHS and RHS lengths), larger LALR tables). |
| 194 | Formerly, many of these numbers ran afoul of 16-bit limits; |
| 195 | now these limits are 32 bits on most hosts. |
| 196 | |
| 197 | * Explicit initial rule |
| 198 | Bison used to play hacks with the initial rule, which the user does |
| 199 | not write. It is now explicit, and visible in the reports and |
| 200 | graphs as rule 0. |
| 201 | |
| 202 | * Useless rules |
| 203 | Before, Bison reported the useless rules, but, although not used, |
| 204 | included them in the parsers. They are now actually removed. |
| 205 | |
| 206 | * Useless rules, useless nonterminals |
| 207 | They are now reported, as a warning, with their locations. |
| 208 | |
| 209 | * Rules never reduced |
| 210 | Rules that can never be reduced because of conflicts are now |
| 211 | reported. |
| 212 | |
| 213 | * Incorrect `Token not used' |
| 214 | On a grammar such as |
| 215 | |
| 216 | %token useless useful |
| 217 | %% |
| 218 | exp: '0' %prec useful; |
| 219 | |
| 220 | where a token was used to set the precedence of the last rule, |
| 221 | bison reported both `useful' and `useless' as useless tokens. |
| 222 | |
| 223 | * Revert the C++ namespace changes introduced in 1.31 |
| 224 | as they caused too many portability hassles. |
| 225 | |
| 226 | * Default locations |
| 227 | By an accident of design, the default computation of @$ was |
| 228 | performed after another default computation was performed: @$ = @1. |
| 229 | The latter is now removed: YYLLOC_DEFAULT is fully responsible of |
| 230 | the computation of @$. |
| 231 | |
| 232 | * Token end-of-file |
| 233 | The token end of file may be specified by the user, in which case, |
| 234 | the user symbol is used in the reports, the graphs, and the verbose |
| 235 | error messages instead of `$end', which remains being the default. |
| 236 | For instance |
| 237 | %token MYEOF 0 |
| 238 | or |
| 239 | %token MYEOF 0 "end of file" |
| 240 | |
| 241 | * Semantic parser |
| 242 | This old option, which has been broken for ages, is removed. |
| 243 | |
| 244 | * New translations |
| 245 | Brazilian Portuguese, thanks to Alexandre Folle de Menezes. |
| 246 | Croatian, thanks to Denis Lackovic. |
| 247 | |
| 248 | * Incorrect token definitions |
| 249 | When given `%token 'a' "A"', Bison used to output `#define 'a' 65'. |
| 250 | |
| 251 | * Token definitions as enums |
| 252 | Tokens are output both as the traditional #define's, and, provided |
| 253 | the compiler supports ANSI C or is a C++ compiler, as enums. |
| 254 | This lets debuggers display names instead of integers. |
| 255 | |
| 256 | * Reports |
| 257 | In addition to --verbose, bison supports --report=THINGS, which |
| 258 | produces additional information: |
| 259 | - itemset |
| 260 | complete the core item sets with their closure |
| 261 | - lookahead |
| 262 | explicitly associate lookaheads to items |
| 263 | - solved |
| 264 | describe shift/reduce conflicts solving. |
| 265 | Bison used to systematically output this information on top of |
| 266 | the report. Solved conflicts are now attached to their states. |
| 267 | |
| 268 | * Type clashes |
| 269 | Previous versions don't complain when there is a type clash on |
| 270 | the default action if the rule has a mid-rule action, such as in: |
| 271 | |
| 272 | %type <foo> bar |
| 273 | %% |
| 274 | bar: '0' {} '0'; |
| 275 | |
| 276 | This is fixed. |
| 277 | |
| 278 | * GNU M4 is now required when using Bison. |
| 279 | \f |
| 280 | Changes in version 1.35, 2002-03-25: |
| 281 | |
| 282 | * C Skeleton |
| 283 | Some projects use Bison's C parser with C++ compilers, and define |
| 284 | YYSTYPE as a class. The recent adjustment of C parsers for data |
| 285 | alignment and 64 bit architectures made this impossible. |
| 286 | |
| 287 | Because for the time being no real solution for C++ parser |
| 288 | generation exists, kludges were implemented in the parser to |
| 289 | maintain this use. In the future, when Bison has C++ parsers, this |
| 290 | kludge will be disabled. |
| 291 | |
| 292 | This kludge also addresses some C++ problems when the stack was |
| 293 | extended. |
| 294 | \f |
| 295 | Changes in version 1.34, 2002-03-12: |
| 296 | |
| 297 | * File name clashes are detected |
| 298 | $ bison foo.y -d -o foo.x |
| 299 | fatal error: header and parser would both be named `foo.x' |
| 300 | |
| 301 | * A missing `;' at the end of a rule triggers a warning |
| 302 | In accordance with POSIX, and in agreement with other |
| 303 | Yacc implementations, Bison will mandate this semicolon in the near |
| 304 | future. This eases the implementation of a Bison parser of Bison |
| 305 | grammars by making this grammar LALR(1) instead of LR(2). To |
| 306 | facilitate the transition, this release introduces a warning. |
| 307 | |
| 308 | * Revert the C++ namespace changes introduced in 1.31, as they caused too |
| 309 | many portability hassles. |
| 310 | |
| 311 | * DJGPP support added. |
| 312 | |
| 313 | * Fix test suite portability problems. |
| 314 | \f |
| 315 | Changes in version 1.33, 2002-02-07: |
| 316 | |
| 317 | * Fix C++ issues |
| 318 | Groff could not be compiled for the definition of size_t was lacking |
| 319 | under some conditions. |
| 320 | |
| 321 | * Catch invalid @n |
| 322 | As is done with $n. |
| 323 | \f |
| 324 | Changes in version 1.32, 2002-01-23: |
| 325 | |
| 326 | * Fix Yacc output file names |
| 327 | |
| 328 | * Portability fixes |
| 329 | |
| 330 | * Italian, Dutch translations |
| 331 | \f |
| 332 | Changes in version 1.31, 2002-01-14: |
| 333 | |
| 334 | * Many Bug Fixes |
| 335 | |
| 336 | * GNU Gettext and %expect |
| 337 | GNU Gettext asserts 10 s/r conflicts, but there are 7. Now that |
| 338 | Bison dies on incorrect %expectations, we fear there will be |
| 339 | too many bug reports for Gettext, so _for the time being_, %expect |
| 340 | does not trigger an error when the input file is named `plural.y'. |
| 341 | |
| 342 | * Use of alloca in parsers |
| 343 | If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use |
| 344 | malloc exclusively. Since 1.29, but was not NEWS'ed. |
| 345 | |
| 346 | alloca is used only when compiled with GCC, to avoid portability |
| 347 | problems as on AIX. |
| 348 | |
| 349 | * When the generated parser lacks debugging code, YYDEBUG is now 0 |
| 350 | (as POSIX requires) instead of being undefined. |
| 351 | |
| 352 | * User Actions |
| 353 | Bison has always permitted actions such as { $$ = $1 }: it adds the |
| 354 | ending semicolon. Now if in Yacc compatibility mode, the semicolon |
| 355 | is no longer output: one has to write { $$ = $1; }. |
| 356 | |
| 357 | * Better C++ compliance |
| 358 | The output parsers try to respect C++ namespaces. |
| 359 | [This turned out to be a failed experiment, and it was reverted later.] |
| 360 | |
| 361 | * Reduced Grammars |
| 362 | Fixed bugs when reporting useless nonterminals. |
| 363 | |
| 364 | * 64 bit hosts |
| 365 | The parsers work properly on 64 bit hosts. |
| 366 | |
| 367 | * Error messages |
| 368 | Some calls to strerror resulted in scrambled or missing error messages. |
| 369 | |
| 370 | * %expect |
| 371 | When the number of shift/reduce conflicts is correct, don't issue |
| 372 | any warning. |
| 373 | |
| 374 | * The verbose report includes the rule line numbers. |
| 375 | |
| 376 | * Rule line numbers are fixed in traces. |
| 377 | |
| 378 | * Swedish translation |
| 379 | |
| 380 | * Parse errors |
| 381 | Verbose parse error messages from the parsers are better looking. |
| 382 | Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'('' |
| 383 | Now: parse error: unexpected '/', expecting "number" or '-' or '(' |
| 384 | |
| 385 | * Fixed parser memory leaks. |
| 386 | When the generated parser was using malloc to extend its stacks, the |
| 387 | previous allocations were not freed. |
| 388 | |
| 389 | * Fixed verbose output file. |
| 390 | Some newlines were missing. |
| 391 | Some conflicts in state descriptions were missing. |
| 392 | |
| 393 | * Fixed conflict report. |
| 394 | Option -v was needed to get the result. |
| 395 | |
| 396 | * %expect |
| 397 | Was not used. |
| 398 | Mismatches are errors, not warnings. |
| 399 | |
| 400 | * Fixed incorrect processing of some invalid input. |
| 401 | |
| 402 | * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H. |
| 403 | |
| 404 | * Fixed some typos in the documentation. |
| 405 | |
| 406 | * %token MY_EOF 0 is supported. |
| 407 | Before, MY_EOF was silently renumbered as 257. |
| 408 | |
| 409 | * doc/refcard.tex is updated. |
| 410 | |
| 411 | * %output, %file-prefix, %name-prefix. |
| 412 | New. |
| 413 | |
| 414 | * --output |
| 415 | New, aliasing `--output-file'. |
| 416 | \f |
| 417 | Changes in version 1.30, 2001-10-26: |
| 418 | |
| 419 | * `--defines' and `--graph' have now an optional argument which is the |
| 420 | output file name. `-d' and `-g' do not change; they do not take any |
| 421 | argument. |
| 422 | |
| 423 | * `%source_extension' and `%header_extension' are removed, failed |
| 424 | experiment. |
| 425 | |
| 426 | * Portability fixes. |
| 427 | \f |
| 428 | Changes in version 1.29, 2001-09-07: |
| 429 | |
| 430 | * The output file does not define const, as this caused problems when used |
| 431 | with common autoconfiguration schemes. If you still use ancient compilers |
| 432 | that lack const, compile with the equivalent of the C compiler option |
| 433 | `-Dconst='. autoconf's AC_C_CONST macro provides one way to do this. |
| 434 | |
| 435 | * Added `-g' and `--graph'. |
| 436 | |
| 437 | * The Bison manual is now distributed under the terms of the GNU FDL. |
| 438 | |
| 439 | * The input and the output files has automatically a similar extension. |
| 440 | |
| 441 | * Russian translation added. |
| 442 | |
| 443 | * NLS support updated; should hopefully be less troublesome. |
| 444 | |
| 445 | * Added the old Bison reference card. |
| 446 | |
| 447 | * Added `--locations' and `%locations'. |
| 448 | |
| 449 | * Added `-S' and `--skeleton'. |
| 450 | |
| 451 | * `%raw', `-r', `--raw' is disabled. |
| 452 | |
| 453 | * Special characters are escaped when output. This solves the problems |
| 454 | of the #line lines with path names including backslashes. |
| 455 | |
| 456 | * New directives. |
| 457 | `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose', |
| 458 | `%debug', `%source_extension' and `%header_extension'. |
| 459 | |
| 460 | * @$ |
| 461 | Automatic location tracking. |
| 462 | \f |
| 463 | Changes in version 1.28, 1999-07-06: |
| 464 | |
| 465 | * Should compile better now with K&R compilers. |
| 466 | |
| 467 | * Added NLS. |
| 468 | |
| 469 | * Fixed a problem with escaping the double quote character. |
| 470 | |
| 471 | * There is now a FAQ. |
| 472 | \f |
| 473 | Changes in version 1.27: |
| 474 | |
| 475 | * The make rule which prevented bison.simple from being created on |
| 476 | some systems has been fixed. |
| 477 | \f |
| 478 | Changes in version 1.26: |
| 479 | |
| 480 | * Bison now uses automake. |
| 481 | |
| 482 | * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>. |
| 483 | |
| 484 | * Token numbers now start at 257 as previously documented, not 258. |
| 485 | |
| 486 | * Bison honors the TMPDIR environment variable. |
| 487 | |
| 488 | * A couple of buffer overruns have been fixed. |
| 489 | |
| 490 | * Problems when closing files should now be reported. |
| 491 | |
| 492 | * Generated parsers should now work even on operating systems which do |
| 493 | not provide alloca(). |
| 494 | \f |
| 495 | Changes in version 1.25, 1995-10-16: |
| 496 | |
| 497 | * Errors in the input grammar are not fatal; Bison keeps reading |
| 498 | the grammar file, and reports all the errors found in it. |
| 499 | |
| 500 | * Tokens can now be specified as multiple-character strings: for |
| 501 | example, you could use "<=" for a token which looks like <=, instead |
| 502 | of chosing a name like LESSEQ. |
| 503 | |
| 504 | * The %token_table declaration says to write a table of tokens (names |
| 505 | and numbers) into the parser file. The yylex function can use this |
| 506 | table to recognize multiple-character string tokens, or for other |
| 507 | purposes. |
| 508 | |
| 509 | * The %no_lines declaration says not to generate any #line preprocessor |
| 510 | directives in the parser file. |
| 511 | |
| 512 | * The %raw declaration says to use internal Bison token numbers, not |
| 513 | Yacc-compatible token numbers, when token names are defined as macros. |
| 514 | |
| 515 | * The --no-parser option produces the parser tables without including |
| 516 | the parser engine; a project can now use its own parser engine. |
| 517 | The actions go into a separate file called NAME.act, in the form of |
| 518 | a switch statement body. |
| 519 | \f |
| 520 | Changes in version 1.23: |
| 521 | |
| 522 | The user can define YYPARSE_PARAM as the name of an argument to be |
| 523 | passed into yyparse. The argument should have type void *. It should |
| 524 | actually point to an object. Grammar actions can access the variable |
| 525 | by casting it to the proper pointer type. |
| 526 | |
| 527 | Line numbers in output file corrected. |
| 528 | \f |
| 529 | Changes in version 1.22: |
| 530 | |
| 531 | --help option added. |
| 532 | \f |
| 533 | Changes in version 1.20: |
| 534 | |
| 535 | Output file does not redefine const for C++. |
| 536 | |
| 537 | Local Variables: |
| 538 | mode: outline |
| 539 | End: |
| 540 | |
| 541 | ----- |
| 542 | |
| 543 | Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free |
| 544 | Software Foundation, Inc. |
| 545 | |
| 546 | This file is part of Bison, the GNU Compiler Compiler. |
| 547 | |
| 548 | Bison is free software; you can redistribute it and/or modify |
| 549 | it under the terms of the GNU General Public License as published by |
| 550 | the Free Software Foundation; either version 2, or (at your option) |
| 551 | any later version. |
| 552 | |
| 553 | Bison is distributed in the hope that it will be useful, |
| 554 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 555 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 556 | GNU General Public License for more details. |
| 557 | |
| 558 | You should have received a copy of the GNU General Public License |
| 559 | along with autoconf; see the file COPYING. If not, write to |
| 560 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 561 | Boston, MA 02111-1307, USA. |