Bison News
----------
-Changes in version 1.49a:
+Changes in version 1.75f, 2002-12-28:
-* Items overflow
- Bison no longer dumps core when there are too many items, it just
- dies.
+* In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
+ locations too. This fixes bugs in error-location computation.
+
+* Bison now uses a Yacc-style format for conflict reports, e.g.,
+ "conflicts: 2 shift/reduce, 1 reduce/reduce".
+
+* Bison now warns if it detects conflicting outputs to the same file,
+ e.g., it generates a warning for "bison -d -o foo.h foo.y" since
+ that command outputs both code and header to foo.h.
+
+Changes in version 1.75e, 2002-12-24:
+
+* If the user does not define YYSTYPE as a macro, Bison now declares it
+ using typedef instead of defining it as a macro. POSIX requires this.
+ For consistency, YYLTYPE is also declared instead of defined.
+
+* %union directives can now have a tag before the `{', e.g., the
+ directive `%union foo {...}' now generates the C code
+ `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
+ The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
+ For consistency, YYLTYPE's struct tag is now `YYLTYPE' instead of `yyltype'.
+
+* `yystype' and `yyltype' are now obsolescent macros instead of being
+ typedefs or tags; they are no longer documented and will be
+ withdrawn in a future release.
+
+* References to the experimental %lex-param and %parse-param directives
+ have been temporarily removed from the manual, since we don't want
+ users to rely upon these features quite yet.
+
+Changes in version 1.75d, 2002-12-13:
+
+* Semicolons are once again optional at the end of grammar rules.
+ This reverts to the behavior of Bison 1.33 and earlier, and improves
+ compatibility with Yacc.
+
+* Type clashes now generate warnings, not errors.
+
+* Yacc command and library now available
+ The Bison distribution now installs a yacc command, as POSIX requires.
+ Also, Bison now installs a small library liby.a containing
+ implementations of Yacc-compatible yyerror and main functions.
+ This library is normally not useful, but POSIX requires it.
+
+* %lex-param, %parse-param
+ These now take just one operand, not two.
+
+* The documentation now emphasizes that yylex and yyerror must be
+ declared before use. C99 requires this.
+
+* The documentation license has been upgraded to version 1.2
+ of the GNU Free Documentation License.
+
+Changes in version 1.75c, 2002-11-25:
+
+* "parse error" -> "syntax error"
+ Bison now uniformly uses the term "syntax error"; formerly, the code
+ and manual sometimes used the term "parse error" instead. POSIX
+ requires "syntax error" in diagnostics, and it was thought better to
+ be consistent.
+
+* "parsing stack overflow..." -> "parser stack overflow"
+ GLR parsers now report "parser stack overflow" as per the Bison manual.
+
+* GLR and inline
+ Users of Bison have to decide how they handle the portability of the
+ C keyword `inline'.
+
+Changes in version 1.75b, 2002-11-13:
+
+* %destructor
+ It is now possible to reclaim the memory associated to symbols
+ discarded during error recovery. This feature is still experimental.
+
+* Bison now parses C99 lexical constructs like UCNs and
+ backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
+
+* --no-line works properly.
+
+* %error-verbose
+ This new directive is preferred over YYERROR_VERBOSE.
+
+* %lex-param, %parse-param
+ These new directives are preferred over PARSE_PARAM and LEX_PARAM.
+ In addition, they provide a means for yyerror to remain pure, and
+ to access to the current location.
+
+ #defining yyerror to steal internal variables is strongly
+ discouraged. It is not guaranteed to work for ever.
+
+* #line
+ Bison now recognizes #line in its input, and forwards them.
+
+* #line
+ File names are properly escaped. E.g. foo\bar.y give #line 123 "foo\\bar.y".
+
+Changes in version 1.75a, 2002-10-24:
+
+* Bison can no longer be built by a K&R C compiler; it requires C89 or
+ later to be built. This change originally took place a few versions
+ ago, but nobody noticed until we recently asked someone to try
+ building Bison with a K&R C compiler.
+
+Changes in version 1.75, 2002-10-14:
+
+* Bison should now work on 64-bit hosts.
+
+* Indonesian translation thanks to Tedi Heriyanto.
+
+* GLR parsers
+ Fix spurious parse errors.
+
+* Pure parsers
+ Some people redefine yyerror to steal yyparse' private variables.
+ Reenable this trick until an official feature replaces it.
+
+* Type Clashes
+ In agreement with POSIX and with other Yaccs, leaving a default
+ action is valid when $$ is untyped, and $1 typed:
+
+ untyped: ... typed;
+
+ but the converse remains an error:
+
+ typed: ... untyped;
+
+* Values of mid-rule actions
+ The following code:
+
+ foo: { ... } { $$ = $1; } ...
+
+ was incorrectly rejected: $1 is defined in the second mid-rule
+ action, and is equal to the $$ of the first mid-rule action.
+
+Changes in version 1.50, 2002-10-04:
+
+* GLR parsing
+ The declaration
+ %glr-parser
+ causes Bison to produce a Generalized LR (GLR) parser, capable of handling
+ almost any context-free grammar, ambiguous or not. The new declarations
+ %dprec and %merge on grammar rules allow parse-time resolution of
+ ambiguities. Contributed by Paul Hilfinger.
+
+ Unfortunately Bison 1.50 does not work properly on 64-bit hosts
+ like the Alpha, so please stick to 32-bit hosts for now.
+
+* Output Directory
+ When not in Yacc compatibility mode, when the output file was not
+ specified, running `bison foo/bar.y' created `foo/bar.c'. It
+ now creates `bar.c'.
+
+* Undefined token
+ The undefined token was systematically mapped to 2 which prevented
+ the use of 2 by the user. This is no longer the case.
+
+* Unknown token numbers
+ If yylex returned an out of range value, yyparse could die. This is
+ no longer the case.
+
+* Error token
+ According to POSIX, the error token must be 256.
+ Bison extends this requirement by making it a preference: *if* the
+ user specified that one of her tokens is numbered 256, then error
+ will be mapped onto another number.
+
+* Verbose error messages
+ They no longer report `..., expecting error or...' for states where
+ error recovery is possible.
+
+* End token
+ Defaults to `$end' instead of `$'.
+
+* Error recovery now conforms to documentation and to POSIX
+ When a Bison-generated parser encounters a syntax error, it now pops
+ the stack until it finds a state that allows shifting the error
+ token. Formerly, it popped the stack until it found a state that
+ allowed some non-error action other than a default reduction on the
+ error token. The new behavior has long been the documented behavior,
+ and has long been required by POSIX. For more details, please see
+ <http://mail.gnu.org/pipermail/bug-bison/2002-May/001452.html>.
+
+* Traces
+ Popped tokens and nonterminals are now reported.
+
+* Larger grammars
+ Larger grammars are now supported (larger token numbers, larger grammar
+ size (= sum of the LHS and RHS lengths), larger LALR tables).
+ Formerly, many of these numbers ran afoul of 16-bit limits;
+ now these limits are 32 bits on most hosts.
+
+* Explicit initial rule
+ Bison used to play hacks with the initial rule, which the user does
+ not write. It is now explicit, and visible in the reports and
+ graphs as rule 0.
+
+* Useless rules
+ Before, Bison reported the useless rules, but, although not used,
+ included them in the parsers. They are now actually removed.
+
+* Useless rules, useless nonterminals
+ They are now reported, as a warning, with their locations.
+
+* Rules never reduced
+ Rules that can never be reduced because of conflicts are now
+ reported.
+
+* Incorrect `Token not used'
+ On a grammar such as
+
+ %token useless useful
+ %%
+ exp: '0' %prec useful;
+
+ where a token was used to set the precedence of the last rule,
+ bison reported both `useful' and `useless' as useless tokens.
+
+* Revert the C++ namespace changes introduced in 1.31
+ as they caused too many portability hassles.
+
+* Default locations
+ By an accident of design, the default computation of @$ was
+ performed after another default computation was performed: @$ = @1.
+ The latter is now removed: YYLLOC_DEFAULT is fully responsible of
+ the computation of @$.
* Token end-of-file
The token end of file may be specified by the user, in which case,
the user symbol is used in the reports, the graphs, and the verbose
- error messages instead of `$', which remains being the defaults.
+ error messages instead of `$end', which remains being the default.
For instance
- %token YYEOF 0
+ %token MYEOF 0
or
- %token YYEOF 0 "end of file"
+ %token MYEOF 0 "end of file"
+
+* Semantic parser
+ This old option, which has been broken for ages, is removed.
+
+* New translations
+ Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
+ Croatian, thanks to Denis Lackovic.
+
+* Incorrect token definitions
+ When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
+
+* Token definitions as enums
+ Tokens are output both as the traditional #define's, and, provided
+ the compiler supports ANSI C or is a C++ compiler, as enums.
+ This lets debuggers display names instead of integers.
+
+* Reports
+ In addition to --verbose, bison supports --report=THINGS, which
+ produces additional information:
+ - itemset
+ complete the core item sets with their closure
+ - lookahead
+ explicitly associate lookaheads to items
+ - solved
+ describe shift/reduce conflicts solving.
+ Bison used to systematically output this information on top of
+ the report. Solved conflicts are now attached to their states.
+
+* Type clashes
+ Previous versions don't complain when there is a type clash on
+ the default action if the rule has a mid-rule action, such as in:
+
+ %type <foo> bar
+ %%
+ bar: '0' {} '0';
+
+ This is fixed.
+
+* GNU M4 is now required when using Bison.
+\f
+Changes in version 1.35, 2002-03-25:
+
+* C Skeleton
+ Some projects use Bison's C parser with C++ compilers, and define
+ YYSTYPE as a class. The recent adjustment of C parsers for data
+ alignment and 64 bit architectures made this impossible.
+
+ Because for the time being no real solution for C++ parser
+ generation exists, kludges were implemented in the parser to
+ maintain this use. In the future, when Bison has C++ parsers, this
+ kludge will be disabled.
+
+ This kludge also addresses some C++ problems when the stack was
+ extended.
+\f
+Changes in version 1.34, 2002-03-12:
+
+* File name clashes are detected
+ $ bison foo.y -d -o foo.x
+ fatal error: header and parser would both be named `foo.x'
+
+* A missing `;' at the end of a rule triggers a warning
+ In accordance with POSIX, and in agreement with other
+ Yacc implementations, Bison will mandate this semicolon in the near
+ future. This eases the implementation of a Bison parser of Bison
+ grammars by making this grammar LALR(1) instead of LR(2). To
+ facilitate the transition, this release introduces a warning.
+
+* Revert the C++ namespace changes introduced in 1.31, as they caused too
+ many portability hassles.
+
+* DJGPP support added.
+
+* Fix test suite portability problems.
+\f
+Changes in version 1.33, 2002-02-07:
+
+* Fix C++ issues
+ Groff could not be compiled for the definition of size_t was lacking
+ under some conditions.
+
+* Catch invalid @n
+ As is done with $n.
+\f
+Changes in version 1.32, 2002-01-23:
+
+* Fix Yacc output file names
+
+* Portability fixes
+
+* Italian, Dutch translations
\f
Changes in version 1.31, 2002-01-14:
* Better C++ compliance
The output parsers try to respect C++ namespaces.
+ [This turned out to be a failed experiment, and it was reverted later.]
* Reduced Grammars
Fixed bugs when reporting useless nonterminals.
* --output
New, aliasing `--output-file'.
\f
-Changes in version 1.30:
+Changes in version 1.30, 2001-10-26:
-* `--defines' and `--graph' have now an optionnal argument which is the
- output file name. `-d' and `-g' do not change, they do not take any
+* `--defines' and `--graph' have now an optional argument which is the
+ output file name. `-d' and `-g' do not change; they do not take any
argument.
* `%source_extension' and `%header_extension' are removed, failed
Local Variables:
mode: outline
End:
+
+-----
+
+Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free
+Software Foundation, Inc.
+
+This file is part of Bison, the GNU Compiler Compiler.
+
+Bison is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+Bison is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with autoconf; see the file COPYING. If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.
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