Bison 1.49c

[Akim Demaille]

GNU Bison 1.49c, which is our 1.50 candidate, is released!

Because the changes within Bison were ambitious, and because some
people already need some of the new features to release their own
package, this release is made although there is still work in
progress.  Nevertheless, there is no known problem with the LALR
parsers: you can safely replace your old Bison copy with this release.

The most significant changes between Bison 1.35 and 1.50 are:

1. most, if not all, the limitations on the size are dropped,

2. a GLR parser output is available, which makes it possible to parse
   any context free grammar, included ambiguous grammars.  This typically
   allows to parses ``naturally'' contrived grammars such as C++'s.
   This is contributed by Paul Hilfinger.

3. the machinery was revamped to ease the creation of new parser types.

Work in progress include:

1. a C++ LALR parser
2. a Java LALR parser
3. means to free semantic value included during error recovery
4. YYPRINT replacement

and many other things.

You may find GNU Bison at the following location:

  ftp://alpha.gnu.org/gnu/bison/bison-1.49c.tar.gz   (944K)
  ftp://alpha.gnu.org/gnu/bison/bison-1.49c.tar.bz2  (754K)

And here are xdelta-style diffs

  ftp://alpha.gnu.org/gnu/bison/bison-1.49b-1.49c.xdelta   (69K)

Here are the MD5 and SHA1 signatures for the compressed tar files:

e2c75c13ffe11ca209b65ccbb130fb1e  bison-1.49c.tar.gz
f2f76c86e8f226702734f721a2cc7b96  bison-1.49c.tar.bz2
b00b8973e25433b35d672798f9ca9705d8f863f0  bison-1.49c.tar.gz
0d774bc00a506194de9337f2c5da1e4accc4ff28  bison-1.49c.tar.bz2

Special thanks to Paul Eggert, Robert Anisko, and Hans Aberg.

NEWS:
Changes in version 1.49c:

* 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.

* Output Directory
  When not in Yacc compatibility mode, when the output file was not
  specified, runnning `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 from the user.  This is no longer the case.

* Unknown token numbers
  If yylex returned a code out of range, yyparse could die.  This is
  no longer the case.

* Error token
  According to POSIX, the error token should be numbered as 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 state 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 `$end', which remains being the default.
  For instance
     %token YYEOF 0
  or
     %token YYEOF 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 fed with `%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 helps debuggers producing symbols instead of values.

* 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.


ChangeLog entries:

**********************************************************************
ChangeLog       27 Sep 2002 14:40:23 -0000      1.839
**********************************************************************
2002-09-27  Akim Demaille  <address@hidden>

        Version 1.49c.

2002-09-27  Akim Demaille  <address@hidden>

        * configure.ac (AM_INIT_AUTOMAKE): We _need_ 1.7.
        (Because of AC_LIBSOURCE).

2002-09-27  Akim Demaille  <address@hidden>

        Playing with Autoscan.

        * configure.ac: Remove the old LIBOBJ tweaks.
        (AC_REPLACE_FUNCS): Add strrchr and strtol.
        * lib/strrchr.c: New.
        * lib/strtol.c: New, from the Coreutils 4.5.1.

2002-09-27  Akim Demaille  <address@hidden>

        Playing with Autoscan.

        * m4/prereq.m4 (jm_PREREQ_ARGMATCH, jm_FUNC_ARGMATCH): New.
        * lib/Makefile.am (libbison_a_SOURCES): No longer include
        argmatch.c and argmatch.h, since they are AC_LIBSOURCE'd.
        * lib/strcasecmp.c, lib/strncasecmp.c, lib/memcmp.c: New, from the
        Coreutils 4.5.1.

2002-09-24  Akim Demaille  <address@hidden>

        * doc/bison.texinfo (Stack Overflow): xref to Recursion.
        (Frequently Asked Questions, Parser Stack Overflow): New.

2002-09-13  Akim Demaille  <address@hidden>

        Playing with autoscan.

        * src/reader.c (get_merge_function): Use xstrdup, not strdup.
        * src/files.c (skeleton_find): Remove, unused.
        * m4/memcmp.m4: New, from the Coreutils 4.5.1.
        * m4/prereq.m4 (jm_PREREQ_QUOTEARG): Run jm_FUNC_MEMCMP.

2002-09-13  Akim Demaille  <address@hidden>

        * configure.ac (AM_INIT_AUTOMAKE): Require Automake 1.6.3.
        * Makefile.am (AUTOMAKE_OPTIONS): Don't.

2002-09-13  Akim Demaille  <address@hidden>

        * configure.ac: Require 2.54.
        s/jm_FUNC_MALLOC/AC_FUNC_MALLOC/.
        s/jm_FUNC_REALLOC/AC_FUNC_REALLOC/.
        * m4/c-bs-a.m4, m4/malloc.m4, m4/mbstate_t.m4, m4/realloc.m4:
        Remove, provided by Autoconf macros.

2002-09-12  Akim Demaille  <address@hidden>

        * m4/prereq.m4: Update, from Coreutils 4.5.1.

2002-09-12  Akim Demaille  <address@hidden>

        * m4/prereq.m4: Update, from Fileutils 4.1.5.
        * configure.ac (jm_PREREQ_TEMPNAME): Invoke it.
        Reported by Martin Mokrejs.

2002-09-10  Akim Demaille  <address@hidden>

        * src/parse-gram.y: Associate a human readable string to each
        token type.
        * tests/regression.at (Invalid inputs): Adjust.

2002-09-10  Gary V. Vaughan  <address@hidden>

        * tests/Makefile.am ($(srcdir)/package.m4): Bison now ships
        with an Autoconf-2.5x style configure.ac.

2002-09-06  Paul Eggert  <address@hidden>

        * doc/bison.texinfo (Conditions): Make explicit that the GPL
        exception applies only to yacc.c.  This is a modification of a
        patch originally suggested by Akim Demaille.

2002-09-06  Akim Demaille  <address@hidden>

        * data/c.m4 (b4_copyright): Move the GPL exception comment from
        here to...
        * data/yacc.c: here.

        * data/lalr1.cc (struct yyltype): Don't define it, since we use
        LocationType.
        (b4_ltype): Default to yy::Location from location.hh.

2002-09-04  Jim Meyering  <address@hidden>

        * data/yacc.c: Guard the declaration of yytoknum also with
        `#ifdef YYPRINT', so it is declared only when used.

2002-09-04  Akim Demaille  <address@hidden>

        * configure.in: Rename as...
        * configure.ac: this.
        Bump to 1.49c.

2002-09-04  Akim Demaille  <address@hidden>

        * src/assoc.c, src/closure.c, src/gram.c, src/injections.c,
        * src/lalr.c, src/LR0.c, src/relation.c, src/tables.c: Don't
        translate maintainer only messages.