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1Bison News
2----------
3
4Changes 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* Traces
30 Popped tokens and nonterminals are now reported.
31
32* Large grammars
33 Large grammars are now supported (large token numbers, large grammar
34 size (= sum of the LHS and RHS lengths), large LALR tables).
35
36* Explicit initial rule
37 Bison used to play hacks with the initial rule, which the user does
38 not write. It is now explicit, and visible in the reports and
39 graphs as rule 0.
40
41* Useless rules
42 Before, Bison reported the useless rules, but, although not used,
43 included them in the parsers. They are now actually removed.
44
45* Incorrect `Token not used'
46 On a grammar such as
47
48 %token useless useful
49 %%
50 exp: '0' %prec useful;
51
52 where a token was used to set the precedence of the last rule,
53 bison reported both `useful' and `useless' as useless tokens.
54
55* Revert the C++ namespace changes introduced in 1.31
56 as they caused too many portability hassles.
57
58* Default locations
59 By an accident of design, the default computation of @$ was
60 performed after another default computation was performed: @$ = @1.
61 The latter is now removed: YYLLOC_DEFAULT is fully responsible of
62 the computation of @$.
63
64* Token end-of-file
65 The token end of file may be specified by the user, in which case,
66 the user symbol is used in the reports, the graphs, and the verbose
67 error messages instead of `$', which remains being the defaults.
68 For instance
69 %token YYEOF 0
70 or
71 %token YYEOF 0 "end of file"
72
73* Semantic parser
74 This old option, which has been broken for ages, is removed.
75
76* New translation
77 Croatian, thanks to Denis Lackovic.
78
79* Incorrect token definitions
80 When fed with `%token 'a' "A"', Bison used to output `#define 'a' 65'.
81
82* Token definitions as enums
83 Tokens are output both as the traditional #define's, and, provided
84 the compiler supports ANSI C or is a C++ compiler, as enums.
85 This helps debuggers producing symbols instead of values.
86
87* Reports
88 In addition to --verbose, bison supports --report=THINGS, which
89 produces additional information:
90 - itemset
91 complete the core item sets with their closure
92 - lookahead
93 explicitly associate lookaheads to items
94 - solved
95 describe shift/reduce conflicts solving.
96 Bison used to systematically output this information on top of
97 the report. Solved conflicts are now attached to their states.
98
99\f
100Changes in version 1.35, 2002-03-25:
101
102* C Skeleton
103 Some projects use Bison's C parser with C++ compilers, and define
104 YYSTYPE as a class. The recent adjustment of C parsers for data
105 alignment and 64 bit architectures made this impossible.
106
107 Because for the time being no real solution for C++ parser
108 generation exists, kludges were implemented in the parser to
109 maintain this use. In the future, when Bison has C++ parsers, this
110 kludge will be disabled.
111
112 This kludge also addresses some C++ problems when the stack was
113 extended.
114
115\f
116Changes in version 1.34, 2002-03-12:
117
118* File name clashes are detected
119 $ bison foo.y -d -o foo.x
120 fatal error: header and parser would both be named `foo.x'
121
122* A missing `;' at the end of a rule triggers a warning
123 In accordance with POSIX, and in agreement with other
124 Yacc implementations, Bison will mandate this semicolon in the near
125 future. This eases the implementation of a Bison parser of Bison
126 grammars by making this grammar LALR(1) instead of LR(2). To
127 facilitate the transition, this release introduces a warning.
128
129* Revert the C++ namespace changes introduced in 1.31, as they caused too
130 many portability hassles.
131
132* DJGPP support added.
133
134* Fix test suite portability problems.
135\f
136Changes in version 1.33, 2002-02-07:
137
138* Fix C++ issues
139 Groff could not be compiled for the definition of size_t was lacking
140 under some conditions.
141
142* Catch invalid @n
143 As is done with $n.
144\f
145Changes in version 1.32, 2002-01-23:
146
147* Fix Yacc output file names
148
149* Portability fixes
150
151* Italian, Dutch translations
152\f
153Changes in version 1.31, 2002-01-14:
154
155* Many Bug Fixes
156
157* GNU Gettext and %expect
158 GNU Gettext asserts 10 s/r conflicts, but there are 7. Now that
159 Bison dies on incorrect %expectations, we fear there will be
160 too many bug reports for Gettext, so _for the time being_, %expect
161 does not trigger an error when the input file is named `plural.y'.
162
163* Use of alloca in parsers
164 If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
165 malloc exclusively. Since 1.29, but was not NEWS'ed.
166
167 alloca is used only when compiled with GCC, to avoid portability
168 problems as on AIX.
169
170* When the generated parser lacks debugging code, YYDEBUG is now 0
171 (as POSIX requires) instead of being undefined.
172
173* User Actions
174 Bison has always permitted actions such as { $$ = $1 }: it adds the
175 ending semicolon. Now if in Yacc compatibility mode, the semicolon
176 is no longer output: one has to write { $$ = $1; }.
177
178* Better C++ compliance
179 The output parsers try to respect C++ namespaces.
180 [This turned out to be a failed experiment, and it was reverted later.]
181
182* Reduced Grammars
183 Fixed bugs when reporting useless nonterminals.
184
185* 64 bit hosts
186 The parsers work properly on 64 bit hosts.
187
188* Error messages
189 Some calls to strerror resulted in scrambled or missing error messages.
190
191* %expect
192 When the number of shift/reduce conflicts is correct, don't issue
193 any warning.
194
195* The verbose report includes the rule line numbers.
196
197* Rule line numbers are fixed in traces.
198
199* Swedish translation
200
201* Parse errors
202 Verbose parse error messages from the parsers are better looking.
203 Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
204 Now: parse error: unexpected '/', expecting "number" or '-' or '('
205
206* Fixed parser memory leaks.
207 When the generated parser was using malloc to extend its stacks, the
208 previous allocations were not freed.
209
210* Fixed verbose output file.
211 Some newlines were missing.
212 Some conflicts in state descriptions were missing.
213
214* Fixed conflict report.
215 Option -v was needed to get the result.
216
217* %expect
218 Was not used.
219 Mismatches are errors, not warnings.
220
221* Fixed incorrect processing of some invalid input.
222
223* Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
224
225* Fixed some typos in the documentation.
226
227* %token MY_EOF 0 is supported.
228 Before, MY_EOF was silently renumbered as 257.
229
230* doc/refcard.tex is updated.
231
232* %output, %file-prefix, %name-prefix.
233 New.
234
235* --output
236 New, aliasing `--output-file'.
237\f
238Changes in version 1.30, 2001-10-26:
239
240* `--defines' and `--graph' have now an optionnal argument which is the
241 output file name. `-d' and `-g' do not change, they do not take any
242 argument.
243
244* `%source_extension' and `%header_extension' are removed, failed
245 experiment.
246
247* Portability fixes.
248\f
249Changes in version 1.29, 2001-09-07:
250
251* The output file does not define const, as this caused problems when used
252 with common autoconfiguration schemes. If you still use ancient compilers
253 that lack const, compile with the equivalent of the C compiler option
254 `-Dconst='. autoconf's AC_C_CONST macro provides one way to do this.
255
256* Added `-g' and `--graph'.
257
258* The Bison manual is now distributed under the terms of the GNU FDL.
259
260* The input and the output files has automatically a similar extension.
261
262* Russian translation added.
263
264* NLS support updated; should hopefully be less troublesome.
265
266* Added the old Bison reference card.
267
268* Added `--locations' and `%locations'.
269
270* Added `-S' and `--skeleton'.
271
272* `%raw', `-r', `--raw' is disabled.
273
274* Special characters are escaped when output. This solves the problems
275 of the #line lines with path names including backslashes.
276
277* New directives.
278 `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
279 `%debug', `%source_extension' and `%header_extension'.
280
281* @$
282 Automatic location tracking.
283\f
284Changes in version 1.28, 1999-07-06:
285
286* Should compile better now with K&R compilers.
287
288* Added NLS.
289
290* Fixed a problem with escaping the double quote character.
291
292* There is now a FAQ.
293\f
294Changes in version 1.27:
295
296* The make rule which prevented bison.simple from being created on
297 some systems has been fixed.
298\f
299Changes in version 1.26:
300
301* Bison now uses automake.
302
303* New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
304
305* Token numbers now start at 257 as previously documented, not 258.
306
307* Bison honors the TMPDIR environment variable.
308
309* A couple of buffer overruns have been fixed.
310
311* Problems when closing files should now be reported.
312
313* Generated parsers should now work even on operating systems which do
314 not provide alloca().
315\f
316Changes in version 1.25, 1995-10-16:
317
318* Errors in the input grammar are not fatal; Bison keeps reading
319the grammar file, and reports all the errors found in it.
320
321* Tokens can now be specified as multiple-character strings: for
322example, you could use "<=" for a token which looks like <=, instead
323of chosing a name like LESSEQ.
324
325* The %token_table declaration says to write a table of tokens (names
326and numbers) into the parser file. The yylex function can use this
327table to recognize multiple-character string tokens, or for other
328purposes.
329
330* The %no_lines declaration says not to generate any #line preprocessor
331directives in the parser file.
332
333* The %raw declaration says to use internal Bison token numbers, not
334Yacc-compatible token numbers, when token names are defined as macros.
335
336* The --no-parser option produces the parser tables without including
337the parser engine; a project can now use its own parser engine.
338The actions go into a separate file called NAME.act, in the form of
339a switch statement body.
340\f
341Changes in version 1.23:
342
343The user can define YYPARSE_PARAM as the name of an argument to be
344passed into yyparse. The argument should have type void *. It should
345actually point to an object. Grammar actions can access the variable
346by casting it to the proper pointer type.
347
348Line numbers in output file corrected.
349\f
350Changes in version 1.22:
351
352--help option added.
353\f
354Changes in version 1.20:
355
356Output file does not redefine const for C++.
357
358Local Variables:
359mode: outline
360End:
361
362-----
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