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