accessed -> addressed (fix typo in changelog entry)

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index f223eb97e6c1de336058d0ba0d697374caecb7bc..784efeb7f389625a742ff18f44e00e102683c24a 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,65 +1,169 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 1.875e, 2004-12-10:
+Changes in version 2.1a:

 
 

-* New directive: %initial-action.
-  This directive allows the user to run arbitrary code (including
-  initializing @$) from yyparse before parsing starts.
+* New warning: unused values
+  Typed right-hand side symbols whose value are not used are reported.
+  For instance:

 
 

-* The option `--report=lookahead' was changed to `--report=look-ahead'.
-  The old spelling still works, but is not documented and will be
-  removed.
+     exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
+       | exp "+" exp
+       ;

 
 

-* 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.
+  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 should be rewritten as:

 
 

-* Goto numbers are no longer arbitrarily limited to 16-bit counts.
+     exp: exp "?" exp ":" exp { $$ = $1 ? $3 : $5; }
+       | exp "+" exp         { $$ = $1 + $3; }
+       ;

 
 

-Changes in version 1.875d, 2004-05-21:
+  However, if the original actions were really intended, the warnings
+  can be suppressed by letting Bison believe the values are used, e.g.:

 
 

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

 
 

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

 
 

-* %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
-  This is a GNU extension.
+     exp: exp { push ($1); } '+' exp { push ($3); sum (); };

 
 

-* A new directive "%expect-rr N" specifies the expected number of
-  reduce/reduce conflicts in GLR parsers.
+  Mid-rule actions that use $$ cause the corresponding value to be
+  set, therefore the following action must use it.  The following rule
+  triggers a warning about $2.

 
 

-* Experimental %destructor support has been added to lalr1.cc.
+     exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; };

 
 

-Changes in version 1.875c, 2003-08-25:
+  The warning is intended to help catching lost values and memory leaks.
+  If a value is ignored, its associated memory typically is not reclaimed.

 
 

-  (Just bug fixes.)
+* %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.

 
 

-Changes in version 1.875b, 2003-06-17:
+* %expect, %expect-rr
+  Incorrect numbers of expected conflicts are now actual errors,
+  instead of warnings.

 
 

-* GLR grammars now support locations.
+* GLR, YACC parsers.
+  The %parse-params are available in the %destructor's (and the
+  experimental %printer's) as per the documentation.

 
 

-* Semicolon changes:
-  - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.
-  - Stray semicolons are no longer allowed at the start of a grammar.
-  - Semicolons are now required after in-grammar declarations.
+* 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.
+
+* 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 "2.1a"'.
+
+* DJGPP support added.
+
+Changes in version 2.1, 2005-09-16:
+
+* The C++ lalr1.cc skeleton supports %lex-param.
+
+* 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.

 
 

-Changes in version 1.875a, 2003-02-01:
+  - 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.

 
 

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

 
 

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

 \f
 Changes in version 1.875, 2003-01-01:
 
 \f
 Changes in version 1.875, 2003-01-01:
 


@@ -395,6 +499,8 @@ Changes in version 1.31, 2002-01-14:
   alloca is used only when compiled with GCC, to avoid portability
   problems as on AIX.
 
   alloca is used only when compiled with GCC, to avoid portability
   problems as on AIX.
 

+* yyparse now returns 2 if memory is exhausted; formerly it dumped core.
+

 * When the generated parser lacks debugging code, YYDEBUG is now 0
   (as POSIX requires) instead of being undefined.
 
 * When the generated parser lacks debugging code, YYDEBUG is now 0
   (as POSIX requires) instead of being undefined.
 


@@ -589,7 +695,7 @@ End:
 
 -----
 
 
 -----
 

-Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
+Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.
 Free Software Foundation, Inc.
 
 This file is part of Bison, the GNU Compiler Compiler.


@@ -606,5 +712,5 @@ 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
 
 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.
+the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+Boston, MA 02110-1301, USA.