X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/72f000b088367bd18a20b3e063bc1ab6a3e0bc15..27622431dcbe1369cebac305a6d76ccd94ef8317:/NEWS?ds=sidebyside diff --git a/NEWS b/NEWS index fd5efa4c..e982759c 100644 --- a/NEWS +++ b/NEWS @@ -1,13 +1,104 @@ Bison News ---------- -Changes in version 2.0a, ????-??-??: +Changes in version 2.1a: -* Bison-generated C parsers use the _ macro to translate strings from - English to the user's language, e.g., _("syntax error"). By default, - _ is defined to be a no-op macro so the strings are not translated. +* Bison now allows multiple %union declarations, and concatenates + their contents together. -* When generating verbose diagnostics, Bison-generated C parsers no longer +* New warning: unused values + Typed right-hand side symbols whose value are not used are reported. + For instance: + + exp: exp "?" exp ":" exp { $1 ? $1 : $3; } + | exp "+" exp + ; + + 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: + + exp: exp "?" exp ":" exp { $$ = $1 ? $3 : $5; } + | exp "+" exp { $$ = $1 + $3; } + ; + + However, if the original actions were really intended, the warnings + can be suppressed by letting Bison believe the values are used, e.g.: + + exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); } + | exp "+" exp { $$ = $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 (); }; + + Mid-rule actions that use $$ cause the corresponding value to be + set, therefore the following action must use it. The following rule + triggers a warning about $2. + + exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; }; + + The warning is intended to help catching lost values and memory leaks. + If a value is ignored, its associated memory typically is not reclaimed. + +* %destructor vs. YYABORT, YYACCEPT, and YYERROR. + Destructors are now called when user code invokes YYABORT, YYACCEPT, + and YYERROR, for all objects on the stack, other than objects + corresponding to the right-hand side of the current rule. + +* %expect, %expect-rr + Incorrect numbers of expected conflicts are now actual errors, + instead of warnings. + +* GLR, YACC parsers. + The %parse-params are available in the %destructor's (and the + experimental %printer's) as per the documentation. + +* Bison now warns if it finds a stray `$' 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. 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, @@ -411,6 +502,8 @@ Changes in version 1.31, 2002-01-14: 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. @@ -605,8 +698,8 @@ 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. @@ -622,5 +715,5 @@ 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 -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.