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[bison.git] / NEWS

diff --git a/NEWS b/NEWS
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--- a/NEWS
+++ b/NEWS
@@ -1,32 +1,554 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 1.23:
+Changes in version 1.875a:

 
 

-The user can define YYPARSE_PARAM as the name of an argument to be passed
-   into yyparse.  The argument should have type void *.
-   It should actually point to an object.
-   Grammar actions can access the variable by casting it
-   to the proper pointer type.
+* New configure option --disable-yacc, to disable installation of the
+  yacc command and -ly library introduced in 1.875 for POSIX conformance.
+\f
+Changes in version 1.875, 2003-01-01:

 
 

-Error in printing reductions fixed.
+* The documentation license has been upgraded to version 1.2
+  of the GNU Free Documentation License.

 
 

-Line numbers in output file corrected.
+* syntax error processing
+
+  - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
+    locations too.  This fixes bugs in error-location computation.
+
+  - %destructor
+    It is now possible to reclaim the memory associated to symbols
+    discarded during error recovery.  This feature is still experimental.
+
+  - %error-verbose
+    This new directive is preferred over YYERROR_VERBOSE.
+
+  - #defining yyerror to steal internal variables is discouraged.
+    It is not guaranteed to work forever.
+
+* POSIX conformance
+
+  - 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.
+
+  - `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.
+
+  - The documentation now emphasizes that yylex and yyerror must be
+    declared before use.  C99 requires this.
+
+  - Bison now parses C99 lexical constructs like UCNs and
+    backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
+
+  - File names are properly escaped in C output.  E.g., foo\bar.y is
+    output as "foo\\bar.y".
+
+  - 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.
+
+  - Type clashes now generate warnings, not errors.
+
+  - If the user does not define YYSTYPE as a macro, Bison now declares it
+    using typedef instead of defining it as a macro.
+    For consistency, YYLTYPE is also declared instead of defined.
+
+* Other compatibility issues
+
+  - %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' not `yyltype'.
+    This is for compatibility with both Yacc and Bison 1.35.
+
+  - `;' is output before the terminating `}' of an action, for
+    compatibility with Bison 1.35.
+
+  - Bison now uses a Yacc-style format for conflict reports, e.g.,
+    `conflicts: 2 shift/reduce, 1 reduce/reduce'.
+
+  - `yystype' and `yyltype' are now obsolescent macros instead of being
+    typedefs or tags; they are no longer documented and are planned to be
+    withdrawn in a future release.

 
 

-Configuration and compilation problems fixed.
+* GLR parser notes
+
+  - GLR and inline
+    Users of Bison have to decide how they handle the portability of the
+    C keyword `inline'.
+
+  - `parsing stack overflow...' -> `parser stack overflow'
+    GLR parsers now report `parser stack overflow' as per the Bison manual.
+
+* 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.
+
+* #line in output files
+  - --no-line works properly.
+
+* 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.

 \f
 \f

-Changes in version 1.22:
+Changes in version 1.75, 2002-10-14:

 
 

---help option added.
+* 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:

 
 

-Configuration and compilation problems fixed.
+       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.

 \f
 \f

-Changes in version 1.21:
+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 @$.
+
+* Token end-of-file
+  The token end of file may be specified by the user, in which case,
+  the user symbol is used in the reports, the graphs, and the verbose
+  error messages instead of `$end', which remains being the default.
+  For instance
+     %token MYEOF 0
+  or
+     %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

 
 

-Configuration and compilation problems fixed.
+* Italian, Dutch translations
+\f
+Changes in version 1.31, 2002-01-14:
+
+* Many Bug Fixes
+
+* GNU Gettext and %expect
+  GNU Gettext asserts 10 s/r conflicts, but there are 7.  Now that
+  Bison dies on incorrect %expectations, we fear there will be
+  too many bug reports for Gettext, so _for the time being_, %expect
+  does not trigger an error when the input file is named `plural.y'.
+
+* Use of alloca in parsers
+  If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
+  malloc exclusively.  Since 1.29, but was not NEWS'ed.
+
+  alloca is used only when compiled with GCC, to avoid portability
+  problems as on AIX.
+
+* When the generated parser lacks debugging code, YYDEBUG is now 0
+  (as POSIX requires) instead of being undefined.
+
+* User Actions
+  Bison has always permitted actions such as { $$ = $1 }: it adds the
+  ending semicolon.  Now if in Yacc compatibility mode, the semicolon
+  is no longer output: one has to write { $$ = $1; }.
+
+* 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.
+
+* 64 bit hosts
+  The parsers work properly on 64 bit hosts.
+
+* Error messages
+  Some calls to strerror resulted in scrambled or missing error messages.
+
+* %expect
+  When the number of shift/reduce conflicts is correct, don't issue
+  any warning.
+
+* The verbose report includes the rule line numbers.
+
+* Rule line numbers are fixed in traces.
+
+* Swedish translation
+
+* Parse errors
+  Verbose parse error messages from the parsers are better looking.
+  Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
+     Now: parse error: unexpected '/', expecting "number" or '-' or '('
+
+* Fixed parser memory leaks.
+  When the generated parser was using malloc to extend its stacks, the
+  previous allocations were not freed.
+
+* Fixed verbose output file.
+  Some newlines were missing.
+  Some conflicts in state descriptions were missing.
+
+* Fixed conflict report.
+  Option -v was needed to get the result.
+
+* %expect
+  Was not used.
+  Mismatches are errors, not warnings.
+
+* Fixed incorrect processing of some invalid input.
+
+* Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
+
+* Fixed some typos in the documentation.
+
+* %token MY_EOF 0 is supported.
+  Before, MY_EOF was silently renumbered as 257.
+
+* doc/refcard.tex is updated.
+
+* %output, %file-prefix, %name-prefix.
+  New.
+
+* --output
+  New, aliasing `--output-file'.
+\f
+Changes in version 1.30, 2001-10-26:
+
+* `--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
+  experiment.
+
+* Portability fixes.
+\f
+Changes in version 1.29, 2001-09-07:
+
+* The output file does not define const, as this caused problems when used
+  with common autoconfiguration schemes.  If you still use ancient compilers
+  that lack const, compile with the equivalent of the C compiler option
+  `-Dconst='.  autoconf's AC_C_CONST macro provides one way to do this.
+
+* Added `-g' and `--graph'.
+
+* The Bison manual is now distributed under the terms of the GNU FDL.
+
+* The input and the output files has automatically a similar extension.
+
+* Russian translation added.
+
+* NLS support updated; should hopefully be less troublesome.
+
+* Added the old Bison reference card.
+
+* Added `--locations' and `%locations'.
+
+* Added `-S' and `--skeleton'.
+
+* `%raw', `-r', `--raw' is disabled.
+
+* Special characters are escaped when output.  This solves the problems
+  of the #line lines with path names including backslashes.
+
+* New directives.
+  `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
+  `%debug', `%source_extension' and `%header_extension'.
+
+* @$
+  Automatic location tracking.
+\f
+Changes in version 1.28, 1999-07-06:
+
+* Should compile better now with K&R compilers.
+
+* Added NLS.
+
+* Fixed a problem with escaping the double quote character.
+
+* There is now a FAQ.
+\f
+Changes in version 1.27:
+
+* The make rule which prevented bison.simple from being created on
+  some systems has been fixed.
+\f
+Changes in version 1.26:
+
+* Bison now uses automake.
+
+* New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
+
+* Token numbers now start at 257 as previously documented, not 258.
+
+* Bison honors the TMPDIR environment variable.
+
+* A couple of buffer overruns have been fixed.
+
+* Problems when closing files should now be reported.
+
+* Generated parsers should now work even on operating systems which do
+  not provide alloca().
+\f
+Changes in version 1.25, 1995-10-16:
+
+* Errors in the input grammar are not fatal; Bison keeps reading
+the grammar file, and reports all the errors found in it.
+
+* Tokens can now be specified as multiple-character strings: for
+example, you could use "<=" for a token which looks like <=, instead
+of chosing a name like LESSEQ.
+
+* The %token_table declaration says to write a table of tokens (names
+and numbers) into the parser file.  The yylex function can use this
+table to recognize multiple-character string tokens, or for other
+purposes.
+
+* The %no_lines declaration says not to generate any #line preprocessor
+directives in the parser file.
+
+* The %raw declaration says to use internal Bison token numbers, not
+Yacc-compatible token numbers, when token names are defined as macros.
+
+* The --no-parser option produces the parser tables without including
+the parser engine; a project can now use its own parser engine.
+The actions go into a separate file called NAME.act, in the form of
+a switch statement body.
+\f
+Changes in version 1.23:
+
+The user can define YYPARSE_PARAM as the name of an argument to be
+passed into yyparse.  The argument should have type void *.  It should
+actually point to an object.  Grammar actions can access the variable
+by casting it to the proper pointer type.
+
+Line numbers in output file corrected.
+\f
+Changes in version 1.22:
+
+--help option added.

 \f
 Changes in version 1.20:
 
 Output file does not redefine const for C++.
 
 \f
 Changes in version 1.20:
 
 Output file does not redefine const for C++.
 

-Configuration and compilation problems fixed.
+Local Variables:
+mode: outline
+End:
+
+-----
+
+Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
+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.