* TODO: Add request from Nelson H. F. Beebe to be able to install

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index 176ce6f27df09ec78e2954172852b64eeade8674..3dca4fe0919a92abdabb0e1d706df9ea4c3ba71e 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,31 +1,58 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 2.1a:
+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
 
 * New warning: unused values

-  Typed right-hand side symbols whose value are not used are reported.
-  For instance:
+  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 "?" exp ":" exp { $1 ? $1 : $3; }

        | exp "+" exp
        ;
 
        | exp "+" exp
        ;
 

-  will trigger a warning about $5 of the first rule, and $3 in the
-  second ($1 is copied to $$ by the default rule).  This example
-  most likely contains two errors, and should be rewritten as:
+  will trigger a warning about $$ 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 { $$ = $1 ? $3 : $5; }
-       | exp "+" exp         { $$ = $1 + $3; }
+     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, the warnings
-  can be suppressed by letting Bison believe the values are used, e.g.:
+  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 { $$ = $1 ? $1 : $3; (void) $5; }
+     exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }

        | exp "+" exp         { $$ = $1; (void) $3; }
        ;
 
        | 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.
 
   The warning is intended to help catching lost values and memory leaks.
   If a value is ignored, its associated memory typically is not reclaimed.
 


@@ -39,14 +66,14 @@ Changes in version 2.1a:
   instead of warnings.
 
 * GLR, YACC parsers.
   instead of warnings.
 
 * GLR, YACC parsers.

-  The %parse-params are available in the %destructor's (and the
-  experimental %printer's) as per the documentation.
+  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"
 
 * Bison now warns if it finds a stray `$' or `@' in an action.
 
 * %require "VERSION"

-  To specify that the grammar file depends on features implemented in
-  Bison version VERSION or higher.
+  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
 
 * lalr1.cc: The token and value types are now class members.
   The tokens were defined as free form enums and cpp macros.  YYSTYPE


@@ -60,10 +87,10 @@ Changes in version 2.1a:
   for previous releases of Bison, and this one.
 
   If you wish to update, then make sure older version of Bison will
   for previous releases of Bison, and this one.
 
   If you wish to update, then make sure older version of Bison will

-  fail using `%require "2.1a"'.
+  fail using `%require "2.2"'.

 
 * DJGPP support added.
 
 * DJGPP support added.

-
+\f

 Changes in version 2.1, 2005-09-16:
 
 * The C++ lalr1.cc skeleton supports %lex-param.
 Changes in version 2.1, 2005-09-16:
 
 * The C++ lalr1.cc skeleton supports %lex-param.


@@ -89,7 +116,7 @@ Changes in version 2.1, 2005-09-16:
   a syntax error associated with '%token NUM "number"' they might
   print 'syntax error, unexpected number' instead of 'syntax error,
   unexpected "number"'.
   a syntax error associated with '%token NUM "number"' they might
   print 'syntax error, unexpected number' instead of 'syntax error,
   unexpected "number"'.

-
+\f

 Changes in version 2.0, 2004-12-25:
 
 * Possibly-incompatible changes
 Changes in version 2.0, 2004-12-25:
 
 * Possibly-incompatible changes


@@ -684,8 +711,8 @@ End:
 
 -----
 
 
 -----
 

-Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
-Free Software Foundation, Inc.
+Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
+2004, 2005, 2006 Free Software Foundation, Inc.

 
 This file is part of Bison, the GNU Compiler Compiler.
 
 
 This file is part of Bison, the GNU Compiler Compiler.