Updated: bison-2.4.2-1

Christopher Faylor cgf-use-the-mailinglist-please@cygwin.com
Sat Apr 10 15:44:00 GMT 2010

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
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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

** %code is now a permanent feature.

  A traditional Yacc prologue directive is written in the form:


  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:


  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.

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