X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/c6b1772473d0a26faa22464df98718d0d0ae2e2e..f0f95a50ee91374ac42b13f201aa42c2038fcada:/NEWS diff --git a/NEWS b/NEWS index c8cab5e0..c94af176 100644 --- a/NEWS +++ b/NEWS @@ -2,16 +2,60 @@ GNU Bison NEWS * Noteworthy changes in release ?.? (????-??-??) [?] +** Future changes + + Bison will stop adding a semicolon at the end of the actions: + + foo.y:2.22: warning: a ';' might be needed at the end of action code + exp: "num" { $$ = $1 } + ^ + foo.y:2.22: future versions of Bison will not add the ';' + + Like other GNU packages, Bison will start using some of the C99 features + for its own code, especially the definition of variables after statements. + The generated C parsers still aim at C90. + ** Incompatible changes *** Obsolete features - Support for YYFAIL is removed (deprecated in Bison 2.4.2). - Support for yystype and yyltype (instead of YYSTYPE and YYLTYPE) - is removed (deprecated in Bison 1.875). - Support for YYPARSE_PARAM is removed (deprecated in Bison 1.875). + Support for YYFAIL is removed (deprecated in Bison 2.4.2): use YYERROR. + + Support for yystype and yyltype is removed (deprecated in Bison 1.875): + use YYSTYPE and YYLTYPE. + + Support for YYLEX_PARAM and YYPARSE_PARAM is removed (deprecated in Bison + 1.875): use %lex-param, %parse-param, or %param. + +** Bug fixes + +*** The epilogue is no longer affected by internal #defines + + The glr.c skeleton uses defines such as #define yylval (yystackp->yyval) in + generated code. These weren't properly undefined before the inclusion of + the user epilogue, so functions such as the following were butchered by the + preprocessor expansion: + + int yylex (YYSTYPE *yylval); + + This is has been fixed: yylval, yynerrs, yychar, and yylloc are now valid + identifiers for user-provided variables. + +*** stdio.h is no longer needed when locations are enabled (yacc.c) + + Changes in Bison 2.7 introduced a dependency on FILE and fprintf when + locations are enabled. This is fixed. + +** Diagnostics reported by Bison + + Most of these features were contributed by Théophile Ranquet and Victor + Santet. + +*** Carets -** Warnings + Version 2.7 introduced caret errors, for a prettier output. These are now + activated by default. The old format can still be used by invoking Bison + with -fno-caret (or -fnone). *** Enhancements of the -Werror option @@ -170,6 +214,8 @@ GNU Bison NEWS ** Java skeleton improvements + Contributed by Paolo Bonzini. + The constants for token names were moved to the Lexer interface. Also, it is possible to add code to the parser's constructors using "%code init" and "%define init_throws". @@ -195,6 +241,16 @@ GNU Bison NEWS used by the scanner, or rejecting invalid combinations from a factory invoked by the user actions). +** Renamed %define variables + + The following variables have been renamed for consistency. Backward + compatibility is ensured, but upgrading is recommended. + + lr.default-reductions -> lr.default-reduction + lr.keep-unreachable-states -> lr.keep-unreachable-state + namespace -> api.namespace + stype -> api.value.type + ** Variable api.token.prefix The variable api.token.prefix changes the way tokens are identified in @@ -211,15 +267,6 @@ GNU Bison NEWS use these prefixed token names, although the grammar itself still uses the short names (as in the sample rule given above). -** Renamed %define variables - - The following variables have been renamed for consistency. Backward - compatibility is ensured, but upgrading is recommended. - - lr.default-reductions -> lr.default-reduction - lr.keep-unreachable-states -> lr.keep-unreachable-state - namespace -> api.namespace - ** Variable parse.error This variable controls the verbosity of error messages. The use of the @@ -228,6 +275,8 @@ GNU Bison NEWS ** Semantic predicates + Contributed by Paul Hilfinger. + The new, experimental, semantic-predicate feature allows actions of the form "%?{ BOOLEAN-EXPRESSION }", which cause syntax errors (as for YYERROR) if the expression evaluates to 0, and are evaluated immediately @@ -240,28 +289,70 @@ GNU Bison NEWS It used to be an error only if used in non GLR mode, _and_ if there are reduce/reduce conflicts. -* Noteworthy changes in release ?.? (????-??-??) [?] +* Noteworthy changes in release 2.7 (2012-12-12) [stable] + +** Bug fixes + + Warnings about uninitialized yylloc in yyparse have been fixed. + + Restored C90 compliance (yet no report was ever made). -** Changes in the format of error messages +** Diagnostics are improved + +*** Changes in the format of error messages This used to be the format of many error reports: - foo.y:5.10-24: result type clash on merge function 'merge': != - foo.y:4.13-27: previous declaration + input.y:2.7-12: %type redeclaration for exp + input.y:1.7-12: previous declaration It is now: - foo.y:5.10-25: result type clash on merge function 'merge': != - foo.y:4.13-27: previous declaration + input.y:2.7-12: error: %type redeclaration for exp + input.y:1.7-12: previous declaration -** Exception safety (lalr1.cc) +*** New format for error reports: carets - The parse function now catches exceptions, uses the %destructors to - release memory (the lookahead symbol and the symbols pushed on the stack) - before re-throwing the exception. + Caret errors have been added to Bison: - This feature is somewhat experimental. User feedback would be - appreciated. + input.y:2.7-12: error: %type redeclaration for exp + %type exp + ^^^^^^ + input.y:1.7-12: previous declaration + %type exp + ^^^^^^ + + or + + input.y:3.20-23: error: ambiguous reference: '$exp' + exp: exp '+' exp { $exp = $1 + $3; }; + ^^^^ + input.y:3.1-3: refers to: $exp at $$ + exp: exp '+' exp { $exp = $1 + $3; }; + ^^^ + input.y:3.6-8: refers to: $exp at $1 + exp: exp '+' exp { $exp = $1 + $3; }; + ^^^ + input.y:3.14-16: refers to: $exp at $3 + exp: exp '+' exp { $exp = $1 + $3; }; + ^^^ + + The default behaviour for now is still not to display these unless + explictly asked with -fcaret (or -fall). However, in a later release, it + will be made the default behavior (but may still be deactivated with + -fno-caret). + +** New value for %define variable: api.pure full + + The %define variable api.pure requests a pure (reentrant) parser. However, + for historical reasons, using it in a location-tracking Yacc parser + resulted in a yyerror function that did not take a location as a + parameter. With this new value, the user may request a better pure parser, + where yyerror does take a location as a parameter (in location-tracking + parsers). + + The use of "%define api.pure true" is deprecated in favor of this new + "%define api.pure full". ** New %define variable: api.location.type (glr.cc, lalr1.cc, lalr1.java) @@ -282,6 +373,15 @@ GNU Bison NEWS position_type are deprecated in favor of api.location.type and api.position.type. +** Exception safety (lalr1.cc) + + The parse function now catches exceptions, uses the %destructors to + release memory (the lookahead symbol and the symbols pushed on the stack) + before re-throwing the exception. + + This feature is somewhat experimental. User feedback would be + appreciated. + ** Graph improvements in DOT and XSLT The graphical presentation of the states is more readable: their shape is @@ -294,19 +394,21 @@ GNU Bison NEWS These changes are present in both --graph output and xml2dot.xsl XSLT processing, with minor (documented) differences. - Two nodes were added to the documentation: Xml and Graphviz. - -* Noteworthy changes in release ?.? (????-??-??) [?] - -** Bug fixes +** %language is no longer an experimental feature. - Warnings about uninitialized yylloc in yyparse have been fixed. + The introduction of this feature, in 2.4, was four years ago. The + --language option and the %language directive are no longer experimental. ** Documentation The sections about shift/reduce and reduce/reduce conflicts resolution have been fixed and extended. + Although introduced more than four years ago, XML and Graphviz reports + were not properly documented. + + The translation of mid-rule actions is now described. + * Noteworthy changes in release 2.6.5 (2012-11-07) [stable] We consider compiler warnings about Bison generated parsers to be bugs. @@ -692,6 +794,7 @@ GNU Bison NEWS These features are experimental in this version. More user feedback will help to stabilize them. + Contributed by Alex Rozenman. ** IELR(1) and canonical LR(1): @@ -1208,6 +1311,7 @@ GNU Bison NEWS The current Java interface is experimental and may evolve. More user feedback will help to stabilize it. + Contributed by Paolo Bonzini. ** %language @@ -1221,6 +1325,7 @@ GNU Bison NEWS Bison can now generate an XML report of the LALR(1) automaton using the new "--xml" option. The current XML schema is experimental and may evolve. More user feedback will help to stabilize it. + Contributed by Wojciech Polak. ** The grammar file may now specify the name of the parser header file using %defines. For example: @@ -2197,7 +2302,7 @@ Output file does not redefine const for C++. ----- -Copyright (C) 1995-2012 Free Software Foundation, Inc. +Copyright (C) 1995-2013 Free Software Foundation, Inc. This file is part of Bison, the GNU Parser Generator.