NEWS

   1 Bison News
   2 ----------
   3
   4 Changes in version 1.49b:
   5
   6 * Undefined token
   7   The undefined token was systematically mapped to 2 which prevented
   8   the use of 2 from the user.  This is no longer the case.
   9
  10 * Unknown token numbers
  11   If yylex returned a code out of range, yyparse could die.  This is
  12   no longer the case.
  13
  14 * Error token
  15   According to POSIX, the error token should be numbered as 256.
  16   Bison extends this requirement by making it a preference: *if* the
  17   user specified that one of her tokens is numbered 256, then error
  18   will be mapped onto another number.
  19
  20 * Error recovery now conforms to documentation and to POSIX
  21   When a Bison-generated parser encounters a syntax error, it now pops
  22   the stack until it finds a state that allows shifting the error
  23   token.  Formerly, it popped the stack until it found a state that
  24   allowed some non-error action other than a default reduction on the
  25   error token.  The new behavior has long been the documented behavior,
  26   and has long been required by POSIX.  For more details, please see
  27   <http://mail.gnu.org/pipermail/bug-bison/2002-May/001452.html>.
  28
  29 * Large grammars
  30   Large grammars are now supported (large token numbers, large grammar
  31   size (= sum of the LHS and RHS lengths), large LALR tables).
  32
  33 * Explicit initial rule
  34   Bison used to play hacks with the initial rule, which the user does
  35   not write.  It is now explicit, and visible in the reports and
  36   graphs as rule 0.
  37
  38 * Useless rules
  39   Before, Bison reported the useless rules, but, although not used,
  40   included them in the parsers.  They are now actually removed.
  41
  42 * Incorrect `Token not used'
  43   On a grammar such as
  44
  45            %token useless useful
  46            %%
  47            exp: '0' %prec useful;
  48
  49   where a token was used to set the precedence of the last rule,
  50   bison reported both `useful' and `useless' as useless tokens.
  51
  52 * Revert the C++ namespace changes introduced in 1.31
  53   as they caused too many portability hassles.
  54
  55 * Default locations
  56   By an accident of design, the default computation of @$ was
  57   performed after another default computation was performed: @$ = @1.
  58   The latter is now removed: YYLLOC_DEFAULT is fully responsible of
  59   the computation of @$.
  60
  61 * Token end-of-file
  62   The token end of file may be specified by the user, in which case,
  63   the user symbol is used in the reports, the graphs, and the verbose
  64   error messages instead of `$', which remains being the defaults.
  65   For instance
  66      %token YYEOF 0
  67   or
  68      %token YYEOF 0 "end of file"
  69
  70 * Semantic parser
  71   This old option, which has been broken for ages, is removed.
  72
  73 * New translations
  74   Croatian, thanks to Denis Lackovic.
  75
  76 * Incorrect token definitions
  77   When fed with `%token 'a' "A"', Bison used to output `#define 'a' 65'.
  78
  79 * Token definitions as enums
  80   Tokens are output both as the traditional #define's, and, provided
  81   the compiler supports ANSI C or is a C++ compiler, as enums.
  82   This helps debuggers producing symbols instead of values.
  83
  84 \f
  85 Changes in version 1.35, 2002-03-25:
  86
  87 * C Skeleton
  88   Some projects use Bison's C parser with C++ compilers, and define
  89   YYSTYPE as a class.  The recent adjustment of C parsers for data
  90   alignment and 64 bit architectures made this impossible.
  91
  92   Because for the time being no real solution for C++ parser
  93   generation exists, kludges were implemented in the parser to
  94   maintain this use.  In the future, when Bison has C++ parsers, this
  95   kludge will be disabled.
  96
  97   This kludge also addresses some C++ problems when the stack was
  98   extended.
  99
 100 \f
 101 Changes in version 1.34, 2002-03-12:
 102
 103 * File name clashes are detected
 104   $ bison foo.y -d -o foo.x
 105   fatal error: header and parser would both be named `foo.x'
 106
 107 * A missing `;' at the end of a rule triggers a warning
 108   In accordance with POSIX, and in agreement with other
 109   Yacc implementations, Bison will mandate this semicolon in the near
 110   future.  This eases the implementation of a Bison parser of Bison
 111   grammars by making this grammar LALR(1) instead of LR(2).  To
 112   facilitate the transition, this release introduces a warning.
 113
 114 * Revert the C++ namespace changes introduced in 1.31, as they caused too
 115   many portability hassles.
 116
 117 * DJGPP support added.
 118
 119 * Fix test suite portability problems.
 120 \f
 121 Changes in version 1.33, 2002-02-07:
 122
 123 * Fix C++ issues
 124   Groff could not be compiled for the definition of size_t was lacking
 125   under some conditions.
 126
 127 * Catch invalid @n
 128   As is done with $n.
 129 \f
 130 Changes in version 1.32, 2002-01-23:
 131
 132 * Fix Yacc output file names
 133
 134 * Portability fixes
 135
 136 * Italian, Dutch translations
 137 \f
 138 Changes in version 1.31, 2002-01-14:
 139
 140 * Many Bug Fixes
 141
 142 * GNU Gettext and %expect
 143   GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
 144   Bison dies on incorrect %expectations, we fear there will be
 145   too many bug reports for Gettext, so _for the time being_, %expect
 146   does not trigger an error when the input file is named `plural.y'.
 147
 148 * Use of alloca in parsers
 149   If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
 150   malloc exclusively.  Since 1.29, but was not NEWS'ed.
 151
 152   alloca is used only when compiled with GCC, to avoid portability
 153   problems as on AIX.
 154
 155 * When the generated parser lacks debugging code, YYDEBUG is now 0
 156   (as POSIX requires) instead of being undefined.
 157
 158 * User Actions
 159   Bison has always permitted actions such as { $$ = $1 }: it adds the
 160   ending semicolon.  Now if in Yacc compatibility mode, the semicolon
 161   is no longer output: one has to write { $$ = $1; }.
 162
 163 * Better C++ compliance
 164   The output parsers try to respect C++ namespaces.
 165   [This turned out to be a failed experiment, and it was reverted later.]
 166
 167 * Reduced Grammars
 168   Fixed bugs when reporting useless nonterminals.
 169
 170 * 64 bit hosts
 171   The parsers work properly on 64 bit hosts.
 172
 173 * Error messages
 174   Some calls to strerror resulted in scrambled or missing error messages.
 175
 176 * %expect
 177   When the number of shift/reduce conflicts is correct, don't issue
 178   any warning.
 179
 180 * The verbose report includes the rule line numbers.
 181
 182 * Rule line numbers are fixed in traces.
 183
 184 * Swedish translation
 185
 186 * Parse errors
 187   Verbose parse error messages from the parsers are better looking.
 188   Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
 189      Now: parse error: unexpected '/', expecting "number" or '-' or '('
 190
 191 * Fixed parser memory leaks.
 192   When the generated parser was using malloc to extend its stacks, the
 193   previous allocations were not freed.
 194
 195 * Fixed verbose output file.
 196   Some newlines were missing.
 197   Some conflicts in state descriptions were missing.
 198
 199 * Fixed conflict report.
 200   Option -v was needed to get the result.
 201
 202 * %expect
 203   Was not used.
 204   Mismatches are errors, not warnings.
 205
 206 * Fixed incorrect processing of some invalid input.
 207
 208 * Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
 209
 210 * Fixed some typos in the documentation.
 211
 212 * %token MY_EOF 0 is supported.
 213   Before, MY_EOF was silently renumbered as 257.
 214
 215 * doc/refcard.tex is updated.
 216
 217 * %output, %file-prefix, %name-prefix.
 218   New.
 219
 220 * --output
 221   New, aliasing `--output-file'.
 222 \f
 223 Changes in version 1.30, 2001-10-26:
 224
 225 * `--defines' and `--graph' have now an optionnal argument which is the
 226   output file name. `-d' and `-g' do not change, they do not take any
 227   argument.
 228
 229 * `%source_extension' and `%header_extension' are removed, failed
 230   experiment.
 231
 232 * Portability fixes.
 233 \f
 234 Changes in version 1.29, 2001-09-07:
 235
 236 * The output file does not define const, as this caused problems when used
 237   with common autoconfiguration schemes.  If you still use ancient compilers
 238   that lack const, compile with the equivalent of the C compiler option
 239   `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
 240
 241 * Added `-g' and `--graph'.
 242
 243 * The Bison manual is now distributed under the terms of the GNU FDL.
 244
 245 * The input and the output files has automatically a similar extension.
 246
 247 * Russian translation added.
 248
 249 * NLS support updated; should hopefully be less troublesome.
 250
 251 * Added the old Bison reference card.
 252
 253 * Added `--locations' and `%locations'.
 254
 255 * Added `-S' and `--skeleton'.
 256
 257 * `%raw', `-r', `--raw' is disabled.
 258
 259 * Special characters are escaped when output.  This solves the problems
 260   of the #line lines with path names including backslashes.
 261
 262 * New directives.
 263   `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
 264   `%debug', `%source_extension' and `%header_extension'.
 265
 266 * @$
 267   Automatic location tracking.
 268 \f
 269 Changes in version 1.28, 1999-07-06:
 270
 271 * Should compile better now with K&R compilers.
 272
 273 * Added NLS.
 274
 275 * Fixed a problem with escaping the double quote character.
 276
 277 * There is now a FAQ.
 278 \f
 279 Changes in version 1.27:
 280
 281 * The make rule which prevented bison.simple from being created on
 282   some systems has been fixed.
 283 \f
 284 Changes in version 1.26:
 285
 286 * Bison now uses automake.
 287
 288 * New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
 289
 290 * Token numbers now start at 257 as previously documented, not 258.
 291
 292 * Bison honors the TMPDIR environment variable.
 293
 294 * A couple of buffer overruns have been fixed.
 295
 296 * Problems when closing files should now be reported.
 297
 298 * Generated parsers should now work even on operating systems which do
 299   not provide alloca().
 300 \f
 301 Changes in version 1.25, 1995-10-16:
 302
 303 * Errors in the input grammar are not fatal; Bison keeps reading
 304 the grammar file, and reports all the errors found in it.
 305
 306 * Tokens can now be specified as multiple-character strings: for
 307 example, you could use "<=" for a token which looks like <=, instead
 308 of chosing a name like LESSEQ.
 309
 310 * The %token_table declaration says to write a table of tokens (names
 311 and numbers) into the parser file.  The yylex function can use this
 312 table to recognize multiple-character string tokens, or for other
 313 purposes.
 314
 315 * The %no_lines declaration says not to generate any #line preprocessor
 316 directives in the parser file.
 317
 318 * The %raw declaration says to use internal Bison token numbers, not
 319 Yacc-compatible token numbers, when token names are defined as macros.
 320
 321 * The --no-parser option produces the parser tables without including
 322 the parser engine; a project can now use its own parser engine.
 323 The actions go into a separate file called NAME.act, in the form of
 324 a switch statement body.
 325 \f
 326 Changes in version 1.23:
 327
 328 The user can define YYPARSE_PARAM as the name of an argument to be
 329 passed into yyparse.  The argument should have type void *.  It should
 330 actually point to an object.  Grammar actions can access the variable
 331 by casting it to the proper pointer type.
 332
 333 Line numbers in output file corrected.
 334 \f
 335 Changes in version 1.22:
 336
 337 --help option added.
 338 \f
 339 Changes in version 1.20:
 340
 341 Output file does not redefine const for C++.
 342
 343 Local Variables:
 344 mode: outline
 345 End:
 346
 347 -----
 348
 349 Copyright (C) 2001, 2002 Free Software Foundation, Inc.
 350
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