Updated: bison-20030307-1

Updated: bison-20030307-1

[Christopher Faylor]

I've made a new version of 'bison' available for download.  This updates
the package to the latest version available from CVS.  It seems to fix
the problem that some people have had with some .y files, most notably
the ones in the cygwin setup sources.

For a brief descripton of this package, see http://cygwin.com/packages/

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Then, run setup and answer all of the questions.  To select the
'bison' package, click on the 'Devel' category and then click on the
'skip' field next to 'bison' until 20030307-1 is displayed.

If you have questions or comments, please send them to the Cygwin
mailing list at: cygwin@cygwin.com .  I would appreciate it if you would
use this mailing list rather than emailing me directly.

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Christopher Faylor

Updated: bison-2.1-1

[Christopher Faylor]

I've made a new version of 'bison' available for download.  This updates
the package to the latest version available from ftp.gnu.org.  I've included
the relevant portions of the Bison NEWS file at the end of this message.

For a brief description of this package, see http://cygwin.com/packages/ .

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the bison package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

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cgf

Changes since bison-20030307-1:

Bison News
----------

Changes in version 2.1, 2005-09-16:

* Bison-generated parsers now support the translation of diagnostics like
  "syntax error" into languages other than English.  The default
  language is still English.  For details, please see the new
  Internationalization section of the Bison manual.  Software
  distributors should also see the new PACKAGING file.  Thanks to
  Bruno Haible for this new feature.

* Wording in the Bison-generated parsers has been changed slightly to
  simplify translation.  In particular, the message "memory exhausted"
  has replaced "parser stack overflow", as the old message was not
  always accurate for modern Bison-generated parsers.

* Destructors are now called when the parser aborts, for all symbols left
  behind on the stack.  Also, the start symbol is now destroyed after a
  successful parse.  In both cases, the behavior was formerly inconsistent.

* When generating verbose diagnostics, Bison-generated parsers no longer
  quote the literal strings associated with tokens.  For example, for
  a syntax error associated with '%token NUM "number"' they might
  print 'syntax error, unexpected number' instead of 'syntax error,
  unexpected "number"'.

Changes in version 2.0, 2004-12-25:

* Possibly-incompatible changes

  - Bison-generated parsers no longer default to using the alloca function
    (when available) to extend the parser stack, due to widespread
    problems in unchecked stack-overflow detection.  You can "#define
    YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read
    the manual to determine safe values for YYMAXDEPTH in that case.

  - Error token location.
    During error recovery, the location of the syntax error is updated
    to cover the whole sequence covered by the error token: it includes
    the shifted symbols thrown away during the first part of the error
    recovery, and the lookahead rejected during the second part.

  - Semicolon changes:
    . Stray semicolons are no longer allowed at the start of a grammar.
    . Semicolons are now required after in-grammar declarations.

  - Unescaped newlines are no longer allowed in character constants or
    string literals.  They were never portable, and GCC 3.4.0 has
    dropped support for them.  Better diagnostics are now generated if
    forget a closing quote.

  - NUL bytes are no longer allowed in Bison string literals, unfortunately.

* New features

  - GLR grammars now support locations.

  - New directive: %initial-action.
    This directive allows the user to run arbitrary code (including
    initializing @$) from yyparse before parsing starts.

  - A new directive "%expect-rr N" specifies the expected number of
    reduce/reduce conflicts in GLR parsers.

  - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
    This is a GNU extension.

  - The option `--report=lookahead' was changed to `--report=look-ahead'.
    The old spelling still works, but is not documented and will be
    removed.

  - Experimental %destructor support has been added to lalr1.cc.

  - New configure option --disable-yacc, to disable installation of the
    yacc command and -ly library introduced in 1.875 for POSIX conformance.

* Bug fixes

  - For now, %expect-count violations are now just warnings, not errors.
    This is for compatibility with Bison 1.75 and earlier (when there are
    reduce/reduce conflicts) and with Bison 1.30 and earlier (when there
    are too many or too few shift/reduce conflicts).  However, in future
    versions of Bison we plan to improve the %expect machinery so that
    these violations will become errors again.

  - Within Bison itself, numbers (e.g., goto numbers) are no longer
    arbitrarily limited to 16-bit counts.

  - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.

Updated: bison-2.3-1

[Christopher Faylor]

I've made a new version of 'bison' available for download.  This updates
the package to the latest version available from ftp.gnu.org.  I've included
the relevant portions of the Bison NEWS file at the end of this message.

For a brief description of this package, see http://cygwin.com/packages/ .

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the bison package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

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cgf

Bison News
----------

Changes in version 2.3, 2006-06-05:

* GLR grammars should now use `YYRECOVERING ()' instead of `YYRECOVERING',
  for compatibility with LALR(1) grammars.

* It is now documented that any definition of YYSTYPE or YYLTYPE should
  be to a type name that does not contain parentheses or brackets.

Changes in version 2.2, 2006-05-19:

* The distribution terms for all Bison-generated parsers now permit
  using the parsers in nonfree programs.  Previously, this permission
  was granted only for Bison-generated LALR(1) parsers in C.

* %name-prefix changes the namespace name in C++ outputs.

* The C++ parsers export their token_type.

* Bison now allows multiple %union declarations, and concatenates
  their contents together.

* New warning: unused values
  Right-hand side symbols whose values are not used are reported,
  if the symbols have destructors.  For instance:

     exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
	| exp "+" exp
	;

  will trigger a warning about $$ and $5 in the first rule, and $3 in
  the second ($1 is copied to $$ by the default rule).  This example
  most likely contains three errors, and could be rewritten as:

     exp: exp "?" exp ":" exp
	    { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
	| exp "+" exp
	    { $$ = $1 ? $1 : $3; if ($1) free ($3); }
	;

  However, if the original actions were really intended, memory leaks
  and all, the warnings can be suppressed by letting Bison believe the
  values are used, e.g.:

     exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
	| exp "+" exp         { $$ = $1; (void) $3; }
	;

  If there are mid-rule actions, the warning is issued if no action
  uses it.  The following triggers no warning: $1 and $3 are used.

     exp: exp { push ($1); } '+' exp { push ($3); sum (); };

  The warning is intended to help catching lost values and memory leaks.
  If a value is ignored, its associated memory typically is not reclaimed.

* %destructor vs. YYABORT, YYACCEPT, and YYERROR.
  Destructors are now called when user code invokes YYABORT, YYACCEPT,
  and YYERROR, for all objects on the stack, other than objects
  corresponding to the right-hand side of the current rule.

* %expect, %expect-rr
  Incorrect numbers of expected conflicts are now actual errors,
  instead of warnings.

* GLR, YACC parsers.
  The %parse-params are available in the destructors (and the
  experimental printers) as per the documentation.

* Bison now warns if it finds a stray `$' or `@' in an action.

* %require "VERSION"
  This specifies that the grammar file depends on features implemented
  in Bison version VERSION or higher.

* lalr1.cc: The token and value types are now class members.
  The tokens were defined as free form enums and cpp macros.  YYSTYPE
  was defined as a free form union.  They are now class members:
  tokens are enumerations of the `yy::parser::token' struct, and the
  semantic values have the `yy::parser::semantic_type' type.

  If you do not want or can update to this scheme, the directive
  `%define "global_tokens_and_yystype" "1"' triggers the global
  definition of tokens and YYSTYPE.  This change is suitable both
  for previous releases of Bison, and this one.

  If you wish to update, then make sure older version of Bison will
  fail using `%require "2.2"'.

* DJGPP support added.

Updated: make-3.81-1

[Christopher Faylor]

I've made a new version of 'make' available for download.  This updates
the package to the latest version available from fedora.redhat.com.
I've included the relevant portions of the NEWS file and the Fedora
ChangeLog at the end of this message.

For a brief description of this package, see http://cygwin.com/packages/ .

Note that the --win32 command line option and "MAKE_MODE" environment
variable are no longer supported in Cygwin's make.  If you need to use a
Makefile which contains MS-DOS path names, then please use a MinGW
version of make.

See: http://mingw.org/ for details on downloading a version of make
which understands MS-DOS path names.  Please! direct any questions about
the MinGW version of make to the appropriate MinGW mailing list.

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the make package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

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starting at the above URL.

cgf

===== Fedora ChangeLog:

* Tue May 23 2006 Petr Machata <pmachata@redhat.com> - 1:3.81-1
- memory patch and error reporting patch were ported to this version.

* Wed Mar 15 2006 Petr Machata <pmachata@redhat.com> 1:3.80-11
- Applied (five years old) patch from Jonathan Kamens to allow make to
  handle several pattern-specific variables (#52962).

  The patch was changed so that it forces make to process pattern
  specific variables in the same order as they appear in file.
  (Upstream make behaves this way, too.)  This is change from old make
  behavior, which processed the variables in reverse order.  In case
  you used only x=a assignments, this had the effect of using the
  first pattern specific variable that matched.  For x+=a this just
  doesn't work, and it produces absolutely nonintuitive results.

- (It would be great if make's target-specific variables were handled
  the same way as pattern-specific ones, just without the pattern
  component.  However current handling is documented and considered a
  feature.)

* Mon Jan 09 2006 Petr Machata <pmachata@redhat.com> 3.80-9
- Applied patch from H.J. Lu.  Somehow reduces make's enormous memory
  consumption. (#175376)

* Mon Aug 22 2005 Jakub Jelinek <jakub@redhat.com> 3.80-8
- make sure errno for error reporting is not lost accross _() calls
- report EOF on read pipe differently from read returning < 0 reporting

===== GNU Make NEWS file:

Version 3.81

* GNU make is ported to OS/2.

* GNU make is ported to MinGW.  The MinGW build is only supported by
  the build_w32.bat batch file; see the file README.W32 for more
  details.

* WARNING: Future backward-incompatibility!
  Up to and including this release, the '$?' variable does not contain
  any prerequisite that does not exist, even though that prerequisite
  might have caused the target to rebuild.  Starting with the _next_
  release of GNU make, '$?' will contain all prerequisites that caused
  the target to be considered out of date.  See this Savannah bug:
  http://savannah.gnu.org/bugs/index.php?func=detailitem&item_id=16051

* WARNING: Backward-incompatibility!
  GNU make now implements a generic "second expansion" feature on the
  prerequisites of both explicit and implicit (pattern) rules.  In order
  to enable this feature, the special target '.SECONDEXPANSION' must be
  defined before the first target which takes advantage of it.  If this
  feature is enabled then after all rules have been parsed the
  prerequisites are expanded again, this time with all the automatic
  variables in scope.  This means that in addition to using standard
  SysV $$@ in prerequisites lists, you can also use complex functions
  such as $$(notdir $$@) etc.  This behavior applies to implicit rules,
  as well, where the second expansion occurs when the rule is matched.
  However, this means that when '.SECONDEXPANSION' is enabled you must
  double-quote any "$" in your filenames; instead of "foo: boo$$bar" you
  now must write "foo: foo$$$$bar".  Note that the SysV $$@ etc. feature,
  which used to be available by default, is now ONLY available when the
  .SECONDEXPANSION target is defined.  If your makefiles take advantage
  of this SysV feature you will need to update them.

* WARNING: Backward-incompatibility!
  In order to comply with POSIX, the way in which GNU make processes
  backslash-newline sequences in command strings has changed.  If your
  makefiles use backslash-newline sequences inside of single-quoted
  strings in command scripts you will be impacted by this change.  See
  the GNU make manual subsection "Splitting Command Lines" (node
  "Splitting Lines"), in section "Command Syntax", chapter "Writing the
  Commands in Rules", for details.

* WARNING: Backward-incompatibility!
  Some previous versions of GNU make had a bug where "#" in a function
  invocation such as $(shell ...) was treated as a make comment.  A
  workaround was to escape these with backslashes.  This bug has been
  fixed: if your makefile uses "\#" in a function invocation the
  backslash is now preserved, so you'll need to remove it.

* New command-line option: -L (--check-symlink-times).  On systems that
  support symbolic links, if this option is given then GNU make will
  use the most recent modification time of any symbolic links that are
  used to resolve target files.  The default behavior remains as it
  always has: use the modification time of the actual target file only.

* The "else" conditional line can now be followed by any other valid
  conditional on the same line: this does not increase the depth of the
  conditional nesting, so only one "endif" is required to close the
  conditional.

* All pattern-specific variables that match a given target are now used
  (previously only the first match was used).

* Target-specific variables can be marked as exportable using the
  "export" keyword.

* In a recursive $(call ...) context, any extra arguments from the outer
  call are now masked in the context of the inner call.

* Implemented a solution for the "thundering herd" problem with "-j -l".
  This version of GNU make uses an algorithm suggested by Thomas Riedl
  <thomas.riedl@siemens.com> to track the number of jobs started in the
  last second and artificially adjust GNU make's view of the system's
  load average accordingly.

* New special variables available in this release:
   - .INCLUDE_DIRS: Expands to a list of directories that make searches
     for included makefiles.
   - .FEATURES: Contains a list of special features available in this
     version of GNU make.
   - .DEFAULT_GOAL: Set the name of the default goal make will
     use if no goals are provided on the command line.
   - MAKE_RESTARTS: If set, then this is the number of times this
     instance of make has been restarted (see "How Makefiles Are Remade"
     in the manual).
   - New automatic variable: $| (added in 3.80, actually): contains all
     the order-only prerequisites defined for the target.

* New functions available in this release:
   - $(lastword ...) returns the last word in the list.  This gives
     identical results as $(word $(words ...) ...), but is much faster.
   - $(abspath ...) returns the absolute path (all "." and ".."
     directories resolved, and any duplicate "/" characters removed) for
     each path provided.
   - $(realpath ...) returns the canonical pathname for each path
     provided.  The canonical pathname is the absolute pathname, with
     all symbolic links resolved as well.
   - $(info ...) prints its arguments to stdout.  No makefile name or
     line number info, etc. is printed.
   - $(flavor ...) returns the flavor of a variable.
   - $(or ...) provides a short-circuiting OR conditional: each argument
     is expanded.  The first true (non-empty) argument is returned; no
     further arguments are expanded.  Expands to empty if there are no
     true arguments.
   - $(and ...) provides a short-circuiting AND conditional: each
     argument is expanded.  The first false (empty) argument is
     returned; no further arguments are expanded.  Expands to the last
     argument if all arguments are true.

* Changes made for POSIX compatibility:
   - Only touch targets (under -t) if they have at least one command.
   - Setting the SHELL make variable does NOT change the value of the
     SHELL environment variable given to programs invoked by make.  As
     an enhancement to POSIX, if you export the make variable SHELL then
     it will be set in the environment, just as before.

* On MS Windows systems, explicitly setting SHELL to a pathname ending
  in "cmd" or "cmd.exe" (case-insensitive) will force GNU make to use
  the DOS command interpreter in batch mode even if a UNIX-like shell
  could be found on the system.

* On VMS there is now support for case-sensitive filesystems such as ODS5.
  See the readme.vms file for information.

* Parallel builds (-jN) no longer require a working Bourne shell on
  Windows platforms.  They work even with the stock Windows shells, such
  as cmd.exe and command.com.

* Updated to autoconf 2.59, automake 1.9.5, and gettext 0.14.1.  Users
  should not be impacted.

* New translations for Swedish, Chinese (simplified), Ukrainian,
  Belarusian, Finnish, Kinyarwandan, and Irish.  Many updated
  translations.

A complete list of bugs fixed in this version is available here:

  http://savannah.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=103

Updated: make-3.81-2

[Christopher Faylor]

I've made a new version of 'make' available for download.  This is
just a simple package refresh to change the dll dependency to
cygintl-8.dll as requested in this message:

http://cygwin.com/ml/cygwin/2008-02/msg00225.html

Note that the --win32 command line option and "MAKE_MODE" environment
variable are no longer supported in Cygwin's make.  If you need to use a
Makefile which contains MS-DOS path names, then please use a MinGW
version of make.

See: http://mingw.org/ for details on downloading a version of make
which understands MS-DOS path names.  Please! direct any questions about
the MinGW version of make to the appropriate MinGW mailing list.

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the make package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

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starting at the above URL.

cgf

Updated: bison-2.4.1-1

[Christopher Faylor]

I've made a new version of 'bison' available for download.  This updates
the package to the latest version available from ftp.gnu.org.  I've included
the relevant portions of the Bison NEWS file at the end of this message.

For a brief description of this package, see http://cygwin.com/packages/ .

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the bison package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

If you want to unsubscribe from the cygwin-announce mailing list, look
at the "List-Unsubscribe: " tag in the email header of this message.
Send email to the address specified there.  It will be in the format:

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If you need more information on unsubscribing, start reading here:

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Please read *all* of the information on unsubscribing that is available
starting at the above URL.

cgf

Bison News
----------

* Changes in version 2.4.1 (2008-12-11):

** In the GLR defines file, unexpanded M4 macros in the yylval and yylloc
   declarations have been fixed.

** Temporary hack for adding a semicolon to the user action.

  Bison used to prepend a trailing semicolon at the end of the user
  action for reductions.  This allowed actions such as

    exp: exp "+" exp { $$ = $1 + $3 };

  instead of

    exp: exp "+" exp { $$ = $1 + $3; };

  Some grammars still depend on this `feature'.  Bison 2.4.1 restores
  the previous behavior in the case of C output (specifically, when
  neither %language or %skeleton or equivalent command-line options
  are used) to leave more time for grammars depending on the old
  behavior to be adjusted.  Future releases of Bison will disable this
  feature.

** A few minor improvements to the Bison manual.

* Changes in version 2.4 (2008-11-02):

** %language is an experimental feature.

  We first introduced this feature in test release 2.3b as a cleaner
  alternative to %skeleton.  Since then, we have discussed the possibility of
  modifying its effect on Bison's output file names.  Thus, in this release,
  we consider %language to be an experimental feature that will likely evolve
  in future releases.

** Forward compatibility with GNU M4 has been improved.

** Several bugs in the C++ skeleton and the experimental Java skeleton have been
  fixed.

* Changes in version 2.3b (2008-05-27):

** The quotes around NAME that used to be required in the following directive
  are now deprecated:

    %define NAME "VALUE"

** The directive `%pure-parser' is now deprecated in favor of:

    %define api.pure

  which has the same effect except that Bison is more careful to warn about
  unreasonable usage in the latter case.

** Push Parsing

  Bison can now generate an LALR(1) parser in C with a push interface.  That
  is, instead of invoking `yyparse', which pulls tokens from `yylex', you can
  push one token at a time to the parser using `yypush_parse', which will
  return to the caller after processing each token.  By default, the push
  interface is disabled.  Either of the following directives will enable it:

    %define api.push_pull "push" // Just push; does not require yylex.
    %define api.push_pull "both" // Push and pull; requires yylex.

  See the new section `A Push Parser' in the Bison manual for details.

  The current push parsing interface is experimental and may evolve.  More user
  feedback will help to stabilize it.

** The -g and --graph options now output graphs in Graphviz DOT format,
  not VCG format.  Like --graph, -g now also takes an optional FILE argument
  and thus cannot be bundled with other short options.

** Java

  Bison can now generate an LALR(1) parser in Java.  The skeleton is
  `data/lalr1.java'.  Consider using the new %language directive instead of
  %skeleton to select it.

  See the new section `Java Parsers' in the Bison manual for details.

  The current Java interface is experimental and may evolve.  More user
  feedback will help to stabilize it.

** %language

  This new directive specifies the programming language of the generated
  parser, which can be C (the default), C++, or Java.  Besides the skeleton
  that Bison uses, the directive affects the names of the generated files if
  the grammar file's name ends in ".y".

** XML Automaton Report

  Bison can now generate an XML report of the LALR(1) automaton using the new
  `--xml' option.  The current XML schema is experimental and may evolve.  More
  user feedback will help to stabilize it.

** The grammar file may now specify the name of the parser header file using
  %defines.  For example:

    %defines "parser.h"

** When reporting useless rules, useless nonterminals, and unused terminals,
  Bison now employs the terms "useless in grammar" instead of "useless",
  "useless in parser" instead of "never reduced", and "unused in grammar"
  instead of "unused".

** Unreachable State Removal

  Previously, Bison sometimes generated parser tables containing unreachable
  states.  A state can become unreachable during conflict resolution if Bison
  disables a shift action leading to it from a predecessor state.  Bison now:

    1. Removes unreachable states.

    2. Does not report any conflicts that appeared in unreachable states.
       WARNING: As a result, you may need to update %expect and %expect-rr
       directives in existing grammar files.

    3. For any rule used only in such states, Bison now reports the rule as
       "useless in parser due to conflicts".

  This feature can be disabled with the following directive:

    %define lr.keep_unreachable_states

  See the %define entry in the `Bison Declaration Summary' in the Bison manual
  for further discussion.

** Lookahead Set Correction in the `.output' Report

  When instructed to generate a `.output' file including lookahead sets
  (using `--report=lookahead', for example), Bison now prints each reduction's
  lookahead set only next to the associated state's one item that (1) is
  associated with the same rule as the reduction and (2) has its dot at the end
  of its RHS.  Previously, Bison also erroneously printed the lookahead set
  next to all of the state's other items associated with the same rule.  This
  bug affected only the `.output' file and not the generated parser source
  code.

** --report-file=FILE is a new option to override the default `.output' file
  name.

** The `=' that used to be required in the following directives is now
  deprecated:

    %file-prefix "parser"
    %name-prefix "c_"
    %output "parser.c"

** An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}'

  Bison 2.3a provided a new set of directives as a more flexible alternative to
  the traditional Yacc prologue blocks.  Those have now been consolidated into
  a single %code directive with an optional qualifier field, which identifies
  the purpose of the code and thus the location(s) where Bison should generate
  it:

    1. `%code          {CODE}' replaces `%after-header  {CODE}'
    2. `%code requires {CODE}' replaces `%start-header  {CODE}'
    3. `%code provides {CODE}' replaces `%end-header    {CODE}'
    4. `%code top      {CODE}' replaces `%before-header {CODE}'

  See the %code entries in section `Bison Declaration Summary' in the Bison
  manual for a summary of the new functionality.  See the new section `Prologue
  Alternatives' for a detailed discussion including the advantages of %code
  over the traditional Yacc prologues.

  The prologue alternatives are experimental.  More user feedback will help to
  determine whether they should become permanent features.

** Revised warning: unset or unused mid-rule values

  Since Bison 2.2, Bison has warned about mid-rule values that are set but not
  used within any of the actions of the parent rule.  For example, Bison warns
  about unused $2 in:

    exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; };

  Now, Bison also warns about mid-rule values that are used but not set.  For
  example, Bison warns about unset $$ in the mid-rule action in:

    exp: '1' { $1 = 1; } '+' exp { $$ = $2 + $4; };

  However, Bison now disables both of these warnings by default since they
  sometimes prove to be false alarms in existing grammars employing the Yacc
  constructs $0 or $-N (where N is some positive integer).

  To enable these warnings, specify the option `--warnings=midrule-values' or
  `-W', which is a synonym for `--warnings=all'.

** Default %destructor or %printer with `<*>' or `<>'

  Bison now recognizes two separate kinds of default %destructor's and
  %printer's:

    1. Place `<*>' in a %destructor/%printer symbol list to define a default
       %destructor/%printer for all grammar symbols for which you have formally
       declared semantic type tags.

    2. Place `<>' in a %destructor/%printer symbol list to define a default
       %destructor/%printer for all grammar symbols without declared semantic
       type tags.

  Bison no longer supports the `%symbol-default' notation from Bison 2.3a.
  `<*>' and `<>' combined achieve the same effect with one exception: Bison no
  longer applies any %destructor to a mid-rule value if that mid-rule value is
  not actually ever referenced using either $$ or $n in a semantic action.

  The default %destructor's and %printer's are experimental.  More user
  feedback will help to determine whether they should become permanent
  features.

  See the section `Freeing Discarded Symbols' in the Bison manual for further
  details.

** %left, %right, and %nonassoc can now declare token numbers.  This is required
  by POSIX.  However, see the end of section `Operator Precedence' in the Bison
  manual for a caveat concerning the treatment of literal strings.

** The nonfunctional --no-parser, -n, and %no-parser options have been
  completely removed from Bison.

* Changes in version 2.3a, 2006-09-13:

** Instead of %union, you can define and use your own union type
  YYSTYPE if your grammar contains at least one <type> tag.
  Your YYSTYPE need not be a macro; it can be a typedef.
  This change is for compatibility with other Yacc implementations,
  and is required by POSIX.

** Locations columns and lines start at 1.
  In accordance with the GNU Coding Standards and Emacs.

** You may now declare per-type and default %destructor's and %printer's:

  For example:

    %union { char *string; }
    %token <string> STRING1
    %token <string> STRING2
    %type  <string> string1
    %type  <string> string2
    %union { char character; }
    %token <character> CHR
    %type  <character> chr
    %destructor { free ($$); } %symbol-default
    %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1
    %destructor { } <character>

  guarantees that, when the parser discards any user-defined symbol that has a
  semantic type tag other than `<character>', it passes its semantic value to
  `free'.  However, when the parser discards a `STRING1' or a `string1', it
  also prints its line number to `stdout'.  It performs only the second
  `%destructor' in this case, so it invokes `free' only once.

  [Although we failed to mention this here in the 2.3a release, the default
  %destructor's and %printer's were experimental, and they were rewritten in
  future versions.]

** Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
  `--yacc', or `%yacc'), Bison no longer generates #define statements for
  associating token numbers with token names.  Removing the #define statements
  helps to sanitize the global namespace during preprocessing, but POSIX Yacc
  requires them.  Bison still generates an enum for token names in all cases.

** Handling of traditional Yacc prologue blocks is now more consistent but
  potentially incompatible with previous releases of Bison.

  As before, you declare prologue blocks in your grammar file with the
  `%{ ... %}' syntax.  To generate the pre-prologue, Bison concatenates all
  prologue blocks that you've declared before the first %union.  To generate
  the post-prologue, Bison concatenates all prologue blocks that you've
  declared after the first %union.

  Previous releases of Bison inserted the pre-prologue into both the header
  file and the code file in all cases except for LALR(1) parsers in C.  In the
  latter case, Bison inserted it only into the code file.  For parsers in C++,
  the point of insertion was before any token definitions (which associate
  token numbers with names).  For parsers in C, the point of insertion was
  after the token definitions.

  Now, Bison never inserts the pre-prologue into the header file.  In the code
  file, it always inserts it before the token definitions.

** Bison now provides a more flexible alternative to the traditional Yacc
  prologue blocks: %before-header, %start-header, %end-header, and
  %after-header.

  For example, the following declaration order in the grammar file reflects the
  order in which Bison will output these code blocks.  However, you are free to
  declare these code blocks in your grammar file in whatever order is most
  convenient for you:

    %before-header {
      /* Bison treats this block like a pre-prologue block: it inserts it into
       * the code file before the contents of the header file.  It does *not*
       * insert it into the header file.  This is a good place to put
       * #include's that you want at the top of your code file.  A common
       * example is `#include "system.h"'.  */
    }
    %start-header {
      /* Bison inserts this block into both the header file and the code file.
       * In both files, the point of insertion is before any Bison-generated
       * token, semantic type, location type, and class definitions.  This is a
       * good place to define %union dependencies, for example.  */
    }
    %union {
      /* Unlike the traditional Yacc prologue blocks, the output order for the
       * new %*-header blocks is not affected by their declaration position
       * relative to any %union in the grammar file.  */
    }
    %end-header {
      /* Bison inserts this block into both the header file and the code file.
       * In both files, the point of insertion is after the Bison-generated
       * definitions.  This is a good place to declare or define public
       * functions or data structures that depend on the Bison-generated
       * definitions.  */
    }
    %after-header {
      /* Bison treats this block like a post-prologue block: it inserts it into
       * the code file after the contents of the header file.  It does *not*
       * insert it into the header file.  This is a good place to declare or
       * define internal functions or data structures that depend on the
       * Bison-generated definitions.  */
    }

  If you have multiple occurrences of any one of the above declarations, Bison
  will concatenate the contents in declaration order.

  [Although we failed to mention this here in the 2.3a release, the prologue
  alternatives were experimental, and they were rewritten in future versions.]

** The option `--report=look-ahead' has been changed to `--report=lookahead'.
  The old spelling still works, but is not documented and may be removed
  in a future release.

Updated: bison-2.4.2-1

[Christopher Faylor]

I've made a new version of 'bison' available for download.  This updates
the package to the latest version available from ftp.gnu.org.  I've included
the relevant portions of the Bison NEWS file at the end of this message.

For a brief description of this package, see http://cygwin.com/packages/ .

To update your installation, click on the "Install Cygwin now" link on
the http://cygwin.com/ web page.  This downloads setup.exe to your
system.  Run setup.exe to install or update the bison package.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

              *** CYGWIN-ANNOUNCE UNSUBSCRIBE INFO ***

If you want to unsubscribe from the cygwin-announce mailing list, look
at the "List-Unsubscribe: " tag in the email header of this message.
Send email to the address specified there.  It will be in the format:

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Please read *all* of the information on unsubscribing that is available
starting at the above URL.

Bison News
----------

* Changes in version 2.4.2 (2010-03-20):

** Some portability problems that resulted in failures and livelocks
   in the test suite on some versions of at least Solaris, AIX, HP-UX,
   RHEL4, and Tru64 have been addressed.  As a result, fatal Bison
   errors should no longer cause M4 to report a broken pipe on the
   affected platforms.

** `%prec IDENTIFIER' requires IDENTIFIER to be defined separately.

  POSIX specifies that an error be reported for any identifier that does
  not appear on the LHS of a grammar rule and that is not defined by
  %token, %left, %right, or %nonassoc.  Bison 2.3b and later lost this
  error report for the case when an identifier appears only after a
  %prec directive.  It is now restored.  However, for backward
  compatibility with recent Bison releases, it is only a warning for
  now.  In Bison 2.5 and later, it will return to being an error.

** Detection of GNU M4 1.4.6 or newer during configure is improved.

** Warnings from gcc's -Wundef option about undefined YYENABLE_NLS,
   YYLTYPE_IS_TRIVIAL, and __STRICT_ANSI__ in C/C++ parsers are now
   avoided.

** %code is now a permanent feature.

  A traditional Yacc prologue directive is written in the form:

    %{CODE%}

  To provide a more flexible alternative, Bison 2.3b introduced the
  %code directive with the following forms for C/C++:

    %code          {CODE}
    %code requires {CODE}
    %code provides {CODE}
    %code top      {CODE}

  These forms are now considered permanent features of Bison.  See the
  %code entries in the section "Bison Declaration Summary" in the Bison
  manual for a summary of their functionality.  See the section
  "Prologue Alternatives" for a detailed discussion including the
  advantages of %code over the traditional Yacc prologue directive.

  Bison's Java feature as a whole including its current usage of %code
  is still considered experimental.

** YYFAIL is deprecated and will eventually be removed.

  YYFAIL has existed for many years as an undocumented feature of
  deterministic parsers in C generated by Bison.  Previously, it was
  documented for Bison's experimental Java parsers.  YYFAIL is no longer
  documented for Java parsers and is formally deprecated in both cases.
  Users are strongly encouraged to migrate to YYERROR, which is
  specified by POSIX.

  Like YYERROR, you can invoke YYFAIL from a semantic action in order to
  induce a syntax error.  The most obvious difference from YYERROR is
  that YYFAIL will automatically invoke yyerror to report the syntax
  error so that you don't have to.  However, there are several other
  subtle differences between YYERROR and YYFAIL, and YYFAIL suffers from
  inherent flaws when %error-verbose or `#define YYERROR_VERBOSE' is
  used.  For a more detailed discussion, see:

    http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html

  The upcoming Bison 2.5 will remove YYFAIL from Java parsers, but
  deterministic parsers in C will continue to implement it.  However,
  because YYFAIL is already flawed, it seems futile to try to make new
  Bison features compatible with it.  Thus, during parser generation,
  Bison 2.5 will produce a warning whenever it discovers YYFAIL in a
  rule action.  In a later release, YYFAIL will be disabled for
  %error-verbose and `#define YYERROR_VERBOSE'.  Eventually, YYFAIL will
  be removed altogether.

  There exists at least one case where Bison 2.5's YYFAIL warning will
  be a false positive.  Some projects add phony uses of YYFAIL and other
  Bison-defined macros for the sole purpose of suppressing C
  preprocessor warnings (from GCC cpp's -Wunused-macros, for example).
  To avoid Bison's future warning, such YYFAIL uses can be moved to the
  epilogue (that is, after the second `%%') in the Bison input file.  In
  this release (2.4.2), Bison already generates its own code to suppress
  C preprocessor warnings for YYFAIL, so projects can remove their own
  phony uses of YYFAIL if compatibility with Bison releases prior to
  2.4.2 is not necessary.

** Internationalization.

  Fix a regression introduced in Bison 2.4: Under some circumstances,
  message translations were not installed although supported by the
  host system.

Updated: bison-2.7-1

[Christopher Faylor]

A new version of 'bison' is available for download.  This updates the
package to the latest version available from ftp.gnu.org.  Relevant
portions of the Bison NEWS file are at the end of this message.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

			==========

GNU Bison NEWS

* Noteworthy changes in release 2.7 (2012-12-12) [stable]

** Bug fixes

  Warnings about uninitialized yylloc in yyparse have been fixed.

  Restored C90 compliance (yet no report was ever made).

** Diagnostics are improved

*** Changes in the format of error messages

  This used to be the format of many error reports:

    input.y:2.7-12: %type redeclaration for exp
    input.y:1.7-12: previous declaration

  It is now:

    input.y:2.7-12: error: %type redeclaration for exp
    input.y:1.7-12:     previous declaration

*** New format for error reports: carets

  Caret errors have been added to Bison:

    input.y:2.7-12: error: %type redeclaration for exp
     %type <sval> exp
           ^^^^^^
    input.y:1.7-12:     previous declaration
     %type <ival> exp
           ^^^^^^

  or

    input.y:3.20-23: error: ambiguous reference: '$exp'
     exp: exp '+' exp { $exp = $1 + $3; };
                        ^^^^
    input.y:3.1-3:       refers to: $exp at $$
     exp: exp '+' exp { $exp = $1 + $3; };
     ^^^
    input.y:3.6-8:       refers to: $exp at $1
     exp: exp '+' exp { $exp = $1 + $3; };
          ^^^
    input.y:3.14-16:     refers to: $exp at $3
     exp: exp '+' exp { $exp = $1 + $3; };
                  ^^^

  The default behaviour for now is still not to display these unless
  explictly asked with -fcaret (or -fall). However, in a later release, it
  will be made the default behavior (but may still be deactivated with
  -fno-caret).

** New value for %define variable: api.pure full

  The %define variable api.pure requests a pure (reentrant) parser. However,
  for historical reasons, using it in a location-tracking Yacc parser
  resulted in a yyerror function that did not take a location as a
  parameter. With this new value, the user may request a better pure parser,
  where yyerror does take a location as a parameter (in location-tracking
  parsers).

  The use of "%define api.pure true" is deprecated in favor of this new
  "%define api.pure full".

** New %define variable: api.location.type (glr.cc, lalr1.cc, lalr1.java)

  The %define variable api.location.type defines the name of the type to use
  for locations.  When defined, Bison no longer generates the position.hh
  and location.hh files, nor does the parser will include them: the user is
  then responsible to define her type.

  This can be used in programs with several parsers to factor their location
  and position files: let one of them generate them, and the others just use
  them.

  This feature was actually introduced, but not documented, in Bison 2.5,
  under the name "location_type" (which is maintained for backward
  compatibility).

  For consistency, lalr1.java's %define variables location_type and
  position_type are deprecated in favor of api.location.type and
  api.position.type.

** Exception safety (lalr1.cc)

  The parse function now catches exceptions, uses the %destructors to
  release memory (the lookahead symbol and the symbols pushed on the stack)
  before re-throwing the exception.

  This feature is somewhat experimental.  User feedback would be
  appreciated.

** Graph improvements in DOT and XSLT

  The graphical presentation of the states is more readable: their shape is
  now rectangular, the state number is clearly displayed, and the items are
  numbered and left-justified.

  The reductions are now explicitly represented as transitions to other
  diamond shaped nodes.

  These changes are present in both --graph output and xml2dot.xsl XSLT
  processing, with minor (documented) differences.

** %language is no longer an experimental feature.

  The introduction of this feature, in 2.4, was four years ago. The
  --language option and the %language directive are no longer experimental.

** Documentation

  The sections about shift/reduce and reduce/reduce conflicts resolution
  have been fixed and extended.

  Although introduced more than four years ago, XML and Graphviz reports
  were not properly documented.

  The translation of mid-rule actions is now described.

* Noteworthy changes in release 2.6.5 (2012-11-07) [stable]

  We consider compiler warnings about Bison generated parsers to be bugs.
  Rather than working around them in your own project, please consider
  reporting them to us.

** Bug fixes

  Warnings about uninitialized yylval and/or yylloc for push parsers with a
  pure interface have been fixed for GCC 4.0 up to 4.8, and Clang 2.9 to
  3.2.

  Other issues in the test suite have been addressed.

  Nul characters are correctly displayed in error messages.

  When possible, yylloc is correctly initialized before calling yylex.  It
  is no longer necessary to initialize it in the %initial-action.

* Noteworthy changes in release 2.6.4 (2012-10-23) [stable]

  Bison 2.6.3's --version was incorrect.  This release fixes this issue.

* Noteworthy changes in release 2.6.3 (2012-10-22) [stable]

** Bug fixes

  Bugs and portability issues in the test suite have been fixed.

  Some errors in translations have been addressed, and --help now directs
  users to the appropriate place to report them.

  Stray Info files shipped by accident are removed.

  Incorrect definitions of YY_, issued by yacc.c when no parser header is
  generated, are removed.

  All the generated headers are self-contained.

** Header guards (yacc.c, glr.c, glr.cc)

  In order to avoid collisions, the header guards are now
  YY_<PREFIX>_<FILE>_INCLUDED, instead of merely <PREFIX>_<FILE>.
  For instance the header generated from

    %define api.prefix "calc"
    %defines "lib/parse.h"

  will use YY_CALC_LIB_PARSE_H_INCLUDED as guard.

** Fix compiler warnings in the generated parser (yacc.c, glr.c)

  The compilation of pure parsers (%define api.pure) can trigger GCC
  warnings such as:

    input.c: In function 'yyparse':
    input.c:1503:12: warning: 'yylval' may be used uninitialized in this
                              function [-Wmaybe-uninitialized]
       *++yyvsp = yylval;
                ^

  This is now fixed; pragmas to avoid these warnings are no longer needed.

  Warnings from clang ("equality comparison with extraneous parentheses" and
  "function declared 'noreturn' should not return") have also been
  addressed.

* Noteworthy changes in release 2.6.2 (2012-08-03) [stable]

** Bug fixes

  Buffer overruns, complaints from Flex, and portability issues in the test
  suite have been fixed.

** Spaces in %lex- and %parse-param (lalr1.cc, glr.cc)

  Trailing end-of-lines in %parse-param or %lex-param would result in
  invalid C++.  This is fixed.

** Spurious spaces and end-of-lines

  The generated files no longer end (nor start) with empty lines.

* Noteworthy changes in release 2.6.1 (2012-07-30) [stable]

  Bison no longer executes user-specified M4 code when processing a grammar.

** Future Changes

  In addition to the removal of the features announced in Bison 2.6, the
  next major release will remove the "Temporary hack for adding a semicolon
  to the user action", as announced in the release 2.5.  Instead of:

    exp: exp "+" exp { $$ = $1 + $3 };

  write:

    exp: exp "+" exp { $$ = $1 + $3; };

** Bug fixes

*** Type names are now properly escaped.

*** glr.cc: set_debug_level and debug_level work as expected.

*** Stray @ or $ in actions

  While Bison used to warn about stray $ or @ in action rules, it did not
  for other actions such as printers, destructors, or initial actions.  It
  now does.

** Type names in actions

  For consistency with rule actions, it is now possible to qualify $$ by a
  type-name in destructors, printers, and initial actions.  For instance:

    %printer { fprintf (yyo, "(%d, %f)", $<ival>$, $<fval>$); } <*> <>;

  will display two values for each typed and untyped symbol (provided
  that YYSTYPE has both "ival" and "fval" fields).

* Noteworthy changes in release 2.6 (2012-07-19) [stable]

** Future Changes

  The next major release of Bison will drop support for the following
  deprecated features.  Please report disagreements to bug-bison@gnu.org.

*** K&R C parsers

  Support for generating parsers in K&R C will be removed.  Parsers
  generated for C support ISO C90, and are tested with ISO C99 and ISO C11
  compilers.

*** Features deprecated since Bison 1.875

  The definitions of yystype and yyltype will be removed; use YYSTYPE and
  YYLTYPE.

  YYPARSE_PARAM and YYLEX_PARAM, deprecated in favor of %parse-param and
  %lex-param, will no longer be supported.

  Support for the preprocessor symbol YYERROR_VERBOSE will be removed, use
  %error-verbose.

*** The generated header will be included (yacc.c)

  Instead of duplicating the content of the generated header (definition of
  YYSTYPE, yyparse declaration etc.), the generated parser will include it,
  as is already the case for GLR or C++ parsers.  This change is deferred
  because existing versions of ylwrap (e.g., Automake 1.12.1) do not support
  it.

** Generated Parser Headers

*** Guards (yacc.c, glr.c, glr.cc)

  The generated headers are now guarded, as is already the case for C++
  parsers (lalr1.cc).  For instance, with --defines=foo.h:

    #ifndef YY_FOO_H
    # define YY_FOO_H
    ...
    #endif /* !YY_FOO_H  */

*** New declarations (yacc.c, glr.c)

  The generated header now declares yydebug and yyparse.  Both honor
  --name-prefix=bar_, and yield

    int bar_parse (void);

  rather than

    #define yyparse bar_parse
    int yyparse (void);

  in order to facilitate the inclusion of several parser headers inside a
  single compilation unit.

*** Exported symbols in C++

  The symbols YYTOKEN_TABLE and YYERROR_VERBOSE, which were defined in the
  header, are removed, as they prevent the possibility of including several
  generated headers from a single compilation unit.

*** YYLSP_NEEDED

  For the same reasons, the undocumented and unused macro YYLSP_NEEDED is no
  longer defined.

** New %define variable: api.prefix

  Now that the generated headers are more complete and properly protected
  against multiple inclusions, constant names, such as YYSTYPE are a
  problem.  While yyparse and others are properly renamed by %name-prefix,
  YYSTYPE, YYDEBUG and others have never been affected by it.  Because it
  would introduce backward compatibility issues in projects not expecting
  YYSTYPE to be renamed, instead of changing the behavior of %name-prefix,
  it is deprecated in favor of a new %define variable: api.prefix.

  The following examples compares both:

    %name-prefix "bar_"               | %define api.prefix "bar_"
    %token <ival> FOO                   %token <ival> FOO
    %union { int ival; }                %union { int ival; }
    %%                                  %%
    exp: 'a';                           exp: 'a';

  bison generates:

    #ifndef BAR_FOO_H                   #ifndef BAR_FOO_H
    # define BAR_FOO_H                  # define BAR_FOO_H

    /* Enabling traces.  */             /* Enabling traces.  */
    # ifndef YYDEBUG                  | # ifndef BAR_DEBUG
                                      > #  if defined YYDEBUG
                                      > #   if YYDEBUG
                                      > #    define BAR_DEBUG 1
                                      > #   else
                                      > #    define BAR_DEBUG 0
                                      > #   endif
                                      > #  else
    #  define YYDEBUG 0               | #   define BAR_DEBUG 0
                                      > #  endif
    # endif                           | # endif

    # if YYDEBUG                      | # if BAR_DEBUG
    extern int bar_debug;               extern int bar_debug;
    # endif                             # endif

    /* Tokens.  */                      /* Tokens.  */
    # ifndef YYTOKENTYPE              | # ifndef BAR_TOKENTYPE
    #  define YYTOKENTYPE             | #  define BAR_TOKENTYPE
       enum yytokentype {             |    enum bar_tokentype {
         FOO = 258                           FOO = 258
       };                                  };
    # endif                             # endif

    #if ! defined YYSTYPE \           | #if ! defined BAR_STYPE \
     && ! defined YYSTYPE_IS_DECLARED |  && ! defined BAR_STYPE_IS_DECLARED
    typedef union YYSTYPE             | typedef union BAR_STYPE
    {                                   {
     int ival;                           int ival;
    } YYSTYPE;                        | } BAR_STYPE;
    # define YYSTYPE_IS_DECLARED 1    | # define BAR_STYPE_IS_DECLARED 1
    #endif                              #endif

    extern YYSTYPE bar_lval;          | extern BAR_STYPE bar_lval;

    int bar_parse (void);               int bar_parse (void);

    #endif /* !BAR_FOO_H  */            #endif /* !BAR_FOO_H  */

* Noteworthy changes in release 2.5.1 (2012-06-05) [stable]

** Future changes:

  The next major release will drop support for generating parsers in K&R C.

** yacc.c: YYBACKUP works as expected.

** glr.c improvements:

*** Location support is eliminated when not requested:

  GLR parsers used to include location-related code even when locations were
  not requested, and therefore not even usable.

*** __attribute__ is preserved:

  __attribute__ is no longer disabled when __STRICT_ANSI__ is defined (i.e.,
  when -std is passed to GCC).

** lalr1.java: several fixes:

  The Java parser no longer throws ArrayIndexOutOfBoundsException if the
  first token leads to a syntax error.  Some minor clean ups.

** Changes for C++:

*** C++11 compatibility:

  C and C++ parsers use "nullptr" instead of "0" when __cplusplus is 201103L
  or higher.

*** Header guards

  The header files such as "parser.hh", "location.hh", etc. used a constant
  name for preprocessor guards, for instance:

    #ifndef BISON_LOCATION_HH
    # define BISON_LOCATION_HH
    ...
    #endif // !BISON_LOCATION_HH

  The inclusion guard is now computed from "PREFIX/FILE-NAME", where lower
  case characters are converted to upper case, and series of
  non-alphanumerical characters are converted to an underscore.

  With "bison -o lang++/parser.cc", "location.hh" would now include:

    #ifndef YY_LANG_LOCATION_HH
    # define YY_LANG_LOCATION_HH
    ...
    #endif // !YY_LANG_LOCATION_HH

*** C++ locations:

  The position and location constructors (and their initialize methods)
  accept new arguments for line and column.  Several issues in the
  documentation were fixed.

** liby is no longer asking for "rpl_fprintf" on some platforms.

** Changes in the manual:

*** %printer is documented

  The "%printer" directive, supported since at least Bison 1.50, is finally
  documented.  The "mfcalc" example is extended to demonstrate it.

  For consistency with the C skeletons, the C++ parsers now also support
  "yyoutput" (as an alias to "debug_stream ()").

*** Several improvements have been made:

  The layout for grammar excerpts was changed to a more compact scheme.
  Named references are motivated.  The description of the automaton
  description file (*.output) is updated to the current format.  Incorrect
  index entries were fixed.  Some other errors were fixed.

** Building bison:

*** Conflicting prototypes with recent/modified Flex.

  Fixed build problems with the current, unreleased, version of Flex, and
  some modified versions of 2.5.35, which have modified function prototypes.

*** Warnings during the build procedure have been eliminated.

*** Several portability problems in the test suite have been fixed:

  This includes warnings with some compilers, unexpected behavior of tools
  such as diff, warning messages from the test suite itself, etc.

*** The install-pdf target works properly:

  Running "make install-pdf" (or -dvi, -html, -info, and -ps) no longer
  halts in the middle of its course.

* Changes in version 2.5 (2011-05-14):

** Grammar symbol names can now contain non-initial dashes:

  Consistently with directives (such as %error-verbose) and with
  %define variables (e.g. push-pull), grammar symbol names may contain
  dashes in any position except the beginning.  This is a GNU
  extension over POSIX Yacc.  Thus, use of this extension is reported
  by -Wyacc and rejected in Yacc mode (--yacc).

** Named references:

  Historically, Yacc and Bison have supported positional references
  ($n, $$) to allow access to symbol values from inside of semantic
  actions code.

  Starting from this version, Bison can also accept named references.
  When no ambiguity is possible, original symbol names may be used
  as named references:

    if_stmt : "if" cond_expr "then" then_stmt ';'
    { $if_stmt = mk_if_stmt($cond_expr, $then_stmt); }

  In the more common case, explicit names may be declared:

    stmt[res] : "if" expr[cond] "then" stmt[then] "else" stmt[else] ';'
    { $res = mk_if_stmt($cond, $then, $else); }

  Location information is also accessible using @name syntax.  When
  accessing symbol names containing dots or dashes, explicit bracketing
  ($[sym.1]) must be used.

  These features are experimental in this version.  More user feedback
  will help to stabilize them.

** IELR(1) and canonical LR(1):

  IELR(1) is a minimal LR(1) parser table generation algorithm.  That
  is, given any context-free grammar, IELR(1) generates parser tables
  with the full language-recognition power of canonical LR(1) but with
  nearly the same number of parser states as LALR(1).  This reduction
  in parser states is often an order of magnitude.  More importantly,
  because canonical LR(1)'s extra parser states may contain duplicate
  conflicts in the case of non-LR(1) grammars, the number of conflicts
  for IELR(1) is often an order of magnitude less as well.  This can
  significantly reduce the complexity of developing of a grammar.

  Bison can now generate IELR(1) and canonical LR(1) parser tables in
  place of its traditional LALR(1) parser tables, which remain the
  default.  You can specify the type of parser tables in the grammar
  file with these directives:

    %define lr.type lalr
    %define lr.type ielr
    %define lr.type canonical-lr

  The default-reduction optimization in the parser tables can also be
  adjusted using "%define lr.default-reductions".  For details on both
  of these features, see the new section "Tuning LR" in the Bison
  manual.

  These features are experimental.  More user feedback will help to
  stabilize them.

** LAC (Lookahead Correction) for syntax error handling:

  Canonical LR, IELR, and LALR can suffer from a couple of problems
  upon encountering a syntax error.  First, the parser might perform
  additional parser stack reductions before discovering the syntax
  error.  Such reductions can perform user semantic actions that are
  unexpected because they are based on an invalid token, and they
  cause error recovery to begin in a different syntactic context than
  the one in which the invalid token was encountered.  Second, when
  verbose error messages are enabled (with %error-verbose or the
  obsolete "#define YYERROR_VERBOSE"), the expected token list in the
  syntax error message can both contain invalid tokens and omit valid
  tokens.

  The culprits for the above problems are %nonassoc, default
  reductions in inconsistent states, and parser state merging.  Thus,
  IELR and LALR suffer the most.  Canonical LR can suffer only if
  %nonassoc is used or if default reductions are enabled for
  inconsistent states.

  LAC is a new mechanism within the parsing algorithm that solves
  these problems for canonical LR, IELR, and LALR without sacrificing
  %nonassoc, default reductions, or state merging.  When LAC is in
  use, canonical LR and IELR behave almost exactly the same for both
  syntactically acceptable and syntactically unacceptable input.
  While LALR still does not support the full language-recognition
  power of canonical LR and IELR, LAC at least enables LALR's syntax
  error handling to correctly reflect LALR's language-recognition
  power.

  Currently, LAC is only supported for deterministic parsers in C.
  You can enable LAC with the following directive:

    %define parse.lac full

  See the new section "LAC" in the Bison manual for additional
  details including a few caveats.

  LAC is an experimental feature.  More user feedback will help to
  stabilize it.

** %define improvements:

*** Can now be invoked via the command line:

  Each of these command-line options

    -D NAME[=VALUE]
    --define=NAME[=VALUE]

    -F NAME[=VALUE]
    --force-define=NAME[=VALUE]

  is equivalent to this grammar file declaration

    %define NAME ["VALUE"]

  except that the manner in which Bison processes multiple definitions
  for the same NAME differs.  Most importantly, -F and --force-define
  quietly override %define, but -D and --define do not.  For further
  details, see the section "Bison Options" in the Bison manual.

*** Variables renamed:

  The following %define variables

    api.push_pull
    lr.keep_unreachable_states

  have been renamed to

    api.push-pull
    lr.keep-unreachable-states

  The old names are now deprecated but will be maintained indefinitely
  for backward compatibility.

*** Values no longer need to be quoted in the grammar file:

  If a %define value is an identifier, it no longer needs to be placed
  within quotations marks.  For example,

    %define api.push-pull "push"

  can be rewritten as

    %define api.push-pull push

*** Unrecognized variables are now errors not warnings.

*** Multiple invocations for any variable is now an error not a warning.

** Unrecognized %code qualifiers are now errors not warnings.

** Character literals not of length one:

  Previously, Bison quietly converted all character literals to length
  one.  For example, without warning, Bison interpreted the operators in
  the following grammar to be the same token:

    exp: exp '++'
       | exp '+' exp
       ;

  Bison now warns when a character literal is not of length one.  In
  some future release, Bison will start reporting an error instead.

** Destructor calls fixed for lookaheads altered in semantic actions:

  Previously for deterministic parsers in C, if a user semantic action
  altered yychar, the parser in some cases used the old yychar value to
  determine which destructor to call for the lookahead upon a syntax
  error or upon parser return.  This bug has been fixed.

** C++ parsers use YYRHSLOC:

  Similarly to the C parsers, the C++ parsers now define the YYRHSLOC
  macro and use it in the default YYLLOC_DEFAULT.  You are encouraged
  to use it.  If, for instance, your location structure has "first"
  and "last" members, instead of

    # define YYLLOC_DEFAULT(Current, Rhs, N)                             \
      do                                                                 \
        if (N)                                                           \
          {                                                              \
            (Current).first = (Rhs)[1].location.first;                   \
            (Current).last  = (Rhs)[N].location.last;                    \
          }                                                              \
        else                                                             \
          {                                                              \
            (Current).first = (Current).last = (Rhs)[0].location.last;   \
          }                                                              \
      while (false)

  use:

    # define YYLLOC_DEFAULT(Current, Rhs, N)                             \
      do                                                                 \
        if (N)                                                           \
          {                                                              \
            (Current).first = YYRHSLOC (Rhs, 1).first;                   \
            (Current).last  = YYRHSLOC (Rhs, N).last;                    \
          }                                                              \
        else                                                             \
          {                                                              \
            (Current).first = (Current).last = YYRHSLOC (Rhs, 0).last;   \
          }                                                              \
      while (false)

** YYLLOC_DEFAULT in C++:

  The default implementation of YYLLOC_DEFAULT used to be issued in
  the header file.  It is now output in the implementation file, after
  the user %code sections so that its #ifndef guard does not try to
  override the user's YYLLOC_DEFAULT if provided.

** YYFAIL now produces warnings and Java parsers no longer implement it:

  YYFAIL has existed for many years as an undocumented feature of
  deterministic parsers in C generated by Bison.  More recently, it was
  a documented feature of Bison's experimental Java parsers.  As
  promised in Bison 2.4.2's NEWS entry, any appearance of YYFAIL in a
  semantic action now produces a deprecation warning, and Java parsers
  no longer implement YYFAIL at all.  For further details, including a
  discussion of how to suppress C preprocessor warnings about YYFAIL
  being unused, see the Bison 2.4.2 NEWS entry.

** Temporary hack for adding a semicolon to the user action:

  Previously, Bison appended a semicolon to every user action for
  reductions when the output language defaulted to C (specifically, when
  neither %yacc, %language, %skeleton, or equivalent command-line
  options were specified).  This allowed actions such as

    exp: exp "+" exp { $$ = $1 + $3 };

  instead of

    exp: exp "+" exp { $$ = $1 + $3; };

  As a first step in removing this misfeature, Bison now issues a
  warning when it appends a semicolon.  Moreover, in cases where Bison
  cannot easily determine whether a semicolon is needed (for example, an
  action ending with a cpp directive or a braced compound initializer),
  it no longer appends one.  Thus, the C compiler might now complain
  about a missing semicolon where it did not before.  Future releases of
  Bison will cease to append semicolons entirely.

** Verbose syntax error message fixes:

  When %error-verbose or the obsolete "#define YYERROR_VERBOSE" is
  specified, syntax error messages produced by the generated parser
  include the unexpected token as well as a list of expected tokens.
  The effect of %nonassoc on these verbose messages has been corrected
  in two ways, but a more complete fix requires LAC, described above:

*** When %nonassoc is used, there can exist parser states that accept no
    tokens, and so the parser does not always require a lookahead token
    in order to detect a syntax error.  Because no unexpected token or
    expected tokens can then be reported, the verbose syntax error
    message described above is suppressed, and the parser instead
    reports the simpler message, "syntax error".  Previously, this
    suppression was sometimes erroneously triggered by %nonassoc when a
    lookahead was actually required.  Now verbose messages are
    suppressed only when all previous lookaheads have already been
    shifted or discarded.

*** Previously, the list of expected tokens erroneously included tokens
    that would actually induce a syntax error because conflicts for them
    were resolved with %nonassoc in the current parser state.  Such
    tokens are now properly omitted from the list.

*** Expected token lists are still often wrong due to state merging
    (from LALR or IELR) and default reductions, which can both add
    invalid tokens and subtract valid tokens.  Canonical LR almost
    completely fixes this problem by eliminating state merging and
    default reductions.  However, there is one minor problem left even
    when using canonical LR and even after the fixes above.  That is,
    if the resolution of a conflict with %nonassoc appears in a later
    parser state than the one at which some syntax error is
    discovered, the conflicted token is still erroneously included in
    the expected token list.  Bison's new LAC implementation,
    described above, eliminates this problem and the need for
    canonical LR.  However, LAC is still experimental and is disabled
    by default.

** Java skeleton fixes:

*** A location handling bug has been fixed.

*** The top element of each of the value stack and location stack is now
    cleared when popped so that it can be garbage collected.

*** Parser traces now print the top element of the stack.

** -W/--warnings fixes:

*** Bison now properly recognizes the "no-" versions of categories:

  For example, given the following command line, Bison now enables all
  warnings except warnings for incompatibilities with POSIX Yacc:

    bison -Wall,no-yacc gram.y

*** Bison now treats S/R and R/R conflicts like other warnings:

  Previously, conflict reports were independent of Bison's normal
  warning system.  Now, Bison recognizes the warning categories
  "conflicts-sr" and "conflicts-rr".  This change has important
  consequences for the -W and --warnings command-line options.  For
  example:

    bison -Wno-conflicts-sr gram.y  # S/R conflicts not reported
    bison -Wno-conflicts-rr gram.y  # R/R conflicts not reported
    bison -Wnone            gram.y  # no conflicts are reported
    bison -Werror           gram.y  # any conflict is an error

  However, as before, if the %expect or %expect-rr directive is
  specified, an unexpected number of conflicts is an error, and an
  expected number of conflicts is not reported, so -W and --warning
  then have no effect on the conflict report.

*** The "none" category no longer disables a preceding "error":

  For example, for the following command line, Bison now reports
  errors instead of warnings for incompatibilities with POSIX Yacc:

    bison -Werror,none,yacc gram.y

*** The "none" category now disables all Bison warnings:

  Previously, the "none" category disabled only Bison warnings for
  which there existed a specific -W/--warning category.  However,
  given the following command line, Bison is now guaranteed to
  suppress all warnings:

    bison -Wnone gram.y

** Precedence directives can now assign token number 0:

  Since Bison 2.3b, which restored the ability of precedence
  directives to assign token numbers, doing so for token number 0 has
  produced an assertion failure.  For example:

    %left END 0

  This bug has been fixed.

* Changes in version 2.4.3 (2010-08-05):

** Bison now obeys -Werror and --warnings=error for warnings about
   grammar rules that are useless in the parser due to conflicts.

** Problems with spawning M4 on at least FreeBSD 8 and FreeBSD 9 have
   been fixed.

** Failures in the test suite for GCC 4.5 have been fixed.

** Failures in the test suite for some versions of Sun Studio C++ have
   been fixed.

** Contrary to Bison 2.4.2's NEWS entry, it has been decided that
   warnings about undefined %prec identifiers will not be converted to
   errors in Bison 2.5.  They will remain warnings, which should be
   sufficient for POSIX while avoiding backward compatibility issues.

** Minor documentation fixes.

Updated: bison-2.7.1-1

[Christopher Faylor]

A new version of 'bison' is available for download.  This updates the
package to the latest version available from ftp.gnu.org.  Relevant
portions of the Bison NEWS file are at the end of this message.

If you have questions or comments, please send them to the Cygwin
mailing list.  I would appreciate it if you would use the mailing list
rather than emailing me directly.

			      =====

GNU Bison NEWS

* Noteworthy changes in release 2.7.1 (2013-04-15) [stable]

** Bug fixes

*** Fix compiler attribute portability (yacc.c)

  With locations enabled, __attribute__ was used unprotected.