Bison News
----------
-Changes in version 1.875f:
+Changes in version 2.1a:
-Changes in version 1.875e, 2004-12-10:
+* GLR, C++ LALR(1) parsers.
+ These parser skeletons are now distributed with the same special
+ license exception that the C LALR(1) parser skeleton has had since
+ Bison 1.24. Hence the FSF imposes no copyright restriction on the
+ output of Bison when it is generating such parsers.
-* New directive: %initial-action.
- This directive allows the user to run arbitrary code (including
- initializing @$) from yyparse before parsing starts.
+* %expect, %expect-rr
+ Incorrect numbers of expected conflicts are now actual errors,
+ instead of warnings.
-* The option `--report=lookahead' was changed to `--report=look-ahead'.
- The old spelling still works, but is not documented and will be
- removed.
+* GLR, YACC parsers.
+ The %parse-params are available in the %destructor's (and the
+ experimental %printer's) as per the documentation.
-* Error token location.
- During error recovery, the location of the syntax error is updated
- to cover the whole sequence covered by the error token: it includes
- the shifted symbols thrown away during the first part of the error
- recovery, and the lookahead rejected during the second part.
+* Bison now warns if it finds a stray `$' or `@' in an action.
-* Goto numbers are no longer arbitrarily limited to 16-bit counts.
+* %require "VERSION"
+ To specify that the grammar file depends on features implemented in
+ Bison version VERSION or higher.
-Changes in version 1.875d, 2004-05-21:
+* lalr1.cc: The token and value types are now class members.
+ The tokens where defined as free form enums and cpp macros. YYSTYPE
+ was defined as a free form union. Both are now class members:
+ tokens are enumerations of the `yy::parser::token' struct, and the
+ semantic values have the `yy::parser::semantic_type' type.
-* 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.
+ 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.
-* NUL bytes are no longer allowed in Bison string literals, unfortunately.
+ If you wish to update, then make sure older version of Bison will
+ fail using `%require "2.1a"'.
-* %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
- This is a GNU extension.
+* DJGPP support added.
-* A new directive "%expect-rr N" specifies the expected number of
- reduce/reduce conflicts in GLR parsers.
+Changes in version 2.1, 2005-09-16:
-* Experimental %destructor support has been added to lalr1.cc.
+* 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.
-Changes in version 1.875c, 2003-08-25:
+* 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.
- (Just bug fixes.)
+* 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.
-Changes in version 1.875b, 2003-06-17:
+* 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"'.
-* GLR grammars now support locations.
+Changes in version 2.0, 2004-12-25:
-* 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.
+* 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.
-Changes in version 1.875a, 2003-02-01:
+ - New directive: %initial-action.
+ This directive allows the user to run arbitrary code (including
+ initializing @$) from yyparse before parsing starts.
-* 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.
+ - A new directive "%expect-rr N" specifies the expected number of
+ reduce/reduce conflicts in GLR parsers.
-* New configure option --disable-yacc, to disable installation of the
- yacc command and -ly library introduced in 1.875 for POSIX conformance.
+ - %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:
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.
-----
-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.
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.
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