Bison News
----------
-Changes in version 2.0a, 2005-05-22:
+Changes in version 2.1a:
-* Bison-generated C parsers now support the translation of diagnostics like
+* New warning: unused values
+ Typed right-hand side symbols whose value are not used are reported.
+ For instance
+
+ exp: exp "?" exp ":" exp { $$ = $1 + $3; }
+ | exp "+" exp
+ ;
+
+ will trigger a warning about $5 of the first rule, and $3 in the
+ second ($1 is copied to $$ by the default rule). To avoid this
+ warning, let Bison believe the value is used, e.g.
+
+ exp: exp "?" exp ":" exp { $$ = $1 + $3; $5; }
+ | exp "+" exp { $$ = $1; $3; }
+
+ This helps catching lost values and memory leaks: if a value is
+ ignored, its associated memory will never be reclaimed.
+
+* %destructor vs. YYABORT, YYACCEPT, and YYERROR.
+ Destructors are now called when user code invokes YYABORT, YYACCEPT,
+ and YYERROR, for all objects on the stack, other than objects
+ corresponding to the right-hand side of the current rule.
+
+* %expect, %expect-rr
+ Incorrect numbers of expected conflicts are now actual errors,
+ instead of warnings.
+
+* GLR, YACC parsers.
+ The %parse-params are available in the %destructor's (and the
+ experimental %printer's) as per the documentation.
+
+* Bison now warns if it finds a stray `$' 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. Thanks to Bruno
- Haible for this new feature.
+ 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.
-* When generating verbose diagnostics, Bison-generated C parsers no longer
+* 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,
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.
projects / bison.git / blobdiff