X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/1f77b2e095492ae95ae6ab33b3ad1f1bf5d758d8..db598939b859043015020a6f1b12d06968bb75e1:/NEWS?ds=inline diff --git a/NEWS b/NEWS index f6e6a8c6..d4f8a750 100644 --- a/NEWS +++ b/NEWS @@ -6,25 +6,68 @@ GNU Bison NEWS *** 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. ** Warnings +*** Enhancements of the -Werror option + + The -Werror=CATEGORY option is now recognized, and will treat specified + warnings as errors. The warnings need not have been explicitly activated + using the -W option, this is similar to what GCC 4.7 does. + + For example, given the following command line, Bison will treat both + warnings related to POSIX Yacc incompatibilities and S/R conflicts as + errors (and only those): + + $ bison -Werror=yacc,error=conflicts-sr input.y + + If no categories are specified, -Werror will make all active warnings into + errors. For example, the following line does the same the previous example: + + $ bison -Werror -Wnone -Wyacc -Wconflicts-sr input.y + + (By default -Wconflicts-sr,conflicts-rr,deprecated,other is enabled.) + + Note that the categories in this -Werror option may not be prefixed with + "no-". However, -Wno-error[=CATEGORY] is valid. + + Note that -y enables -Werror=yacc. Therefore it is now possible to require + Yacc-like behavior (e.g., always generate y.tab.c), but to report + incompatibilities as warnings: "-y -Wno-error=yacc". + +*** The display of warnings is now richer + + The option that controls a given warning is now displayed: + + foo.y:4.6: warning: type clash on default action: != [-Wother] + + In the case of warnings treated as errors, the prefix is changed from + "warning: " to "error: ", and the suffix is displayed, in a manner similar + to GCC, as [-Werror=CATEGORY]. + + For instance, where the previous version of Bison would report (and exit + with failure): + + bison: warnings being treated as errors + input.y:1.1: warning: stray ',' treated as white space + + it now reports: + + input.y:1.1: error: stray ',' treated as white space [-Werror=other] + *** Deprecated constructs The new 'deprecated' warning category flags obsolete constructs whose support will be discontinued. It is enabled by default. These warnings used to be reported as 'other' warnings. -*** Warning categories are now displayed - - For instance: - - foo.y:4.6: warning: type clash on default action: != [-Wother] - *** Useless semantic types Bison now warns about useless (uninhabited) semantic types. Since @@ -67,6 +110,52 @@ GNU Bison NEWS %printer {} token1 %destructor {} token2 +*** Conflicts + + The warnings and error messages about shift/reduce and reduce/reduce + conflicts have been normalized. For instance on the following foo.y file: + + %glr-parser + %% + exp: exp '+' exp | '0' | '0'; + + compare the previous version of bison: + + $ bison foo.y + foo.y: conflicts: 1 shift/reduce, 2 reduce/reduce + $ bison -Werror foo.y + bison: warnings being treated as errors + foo.y: conflicts: 1 shift/reduce, 2 reduce/reduce + + with the new behavior: + + $ bison foo.y + foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr] + foo.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr] + $ bison -Werror foo.y + foo.y: error: 1 shift/reduce conflict [-Werror=conflicts-sr] + foo.y: error: 2 reduce/reduce conflicts [-Werror=conflicts-rr] + + When %expect or %expect-rr is used, such as with bar.y: + + %expect 0 + %glr-parser + %% + exp: exp '+' exp | '0' | '0'; + + Former behavior: + + $ bison bar.y + bar.y: conflicts: 1 shift/reduce, 2 reduce/reduce + bar.y: expected 0 shift/reduce conflicts + bar.y: expected 0 reduce/reduce conflicts + + New one: + + $ bison bar.y + bar.y: error: shift/reduce conflicts: 1 found, 0 expected + bar.y: error: reduce/reduce conflicts: 2 found, 0 expected + ** Additional yylex/yyparse arguments The new directive %param declares additional arguments to both yylex and @@ -109,14 +198,14 @@ GNU Bison NEWS used by the scanner, or rejecting invalid combinations from a factory invoked by the user actions). -** Variable api.tokens.prefix +** Variable api.token.prefix - The variable api.tokens.prefix changes the way tokens are identified in + The variable api.token.prefix changes the way tokens are identified in the generated files. This is especially useful to avoid collisions with identifiers in the target language. For instance %token FILE for ERROR - %define api.tokens.prefix "TOK_" + %define api.token.prefix "TOK_" %% start: FILE for ERROR; @@ -125,11 +214,15 @@ GNU Bison NEWS use these prefixed token names, although the grammar itself still uses the short names (as in the sample rule given above). -** Variable api.namespace +** Renamed %define variables - The 'namespace' variable is renamed 'api.namespace'. Backward + 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 @@ -145,8 +238,197 @@ GNU Bison NEWS the programmer to prune possible parses based on the values of run-time expressions. -* Noteworthy changes in release ?.? (????-??-??) [?] +** The directive %expect-rr is now an error in non GLR mode + + It used to be an error only if used in non GLR mode, _and_ if there are + reduce/reduce conflicts. + +* 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). + +** Diagnostics are improved + +*** Changes in the format of error messages + + This used to be the format of many error reports: + + input.y:2.7-12: %type redeclaration for exp + input.y:1.7-12: previous declaration + + It is now: + + input.y:2.7-12: error: %type redeclaration for exp + input.y:1.7-12: previous declaration + +*** New format for error reports: carets + + Caret errors have been added to Bison: + 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) + + The %define variable api.location.type defines the name of the type to use + for locations. When defined, Bison no longer generates the position.hh + and location.hh files, nor does the parser will include them: the user is + then responsible to define her type. + + This can be used in programs with several parsers to factor their location + and position files: let one of them generate them, and the others just use + them. + + This feature was actually introduced, but not documented, in Bison 2.5, + under the name "location_type" (which is maintained for backward + compatibility). + + For consistency, lalr1.java's %define variables location_type and + 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 + now rectangular, the state number is clearly displayed, and the items are + numbered and left-justified. + + The reductions are now explicitly represented as transitions to other + diamond shaped nodes. + + These changes are present in both --graph output and xml2dot.xsl XSLT + processing, with minor (documented) differences. + +** %language is no longer an experimental feature. + + 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. + Rather than working around them in your own project, please consider + reporting them to us. + +** Bug fixes + + Warnings about uninitialized yylval and/or yylloc for push parsers with a + pure interface have been fixed for GCC 4.0 up to 4.8, and Clang 2.9 to + 3.2. + + Other issues in the test suite have been addressed. + + Nul characters are correctly displayed in error messages. + + When possible, yylloc is correctly initialized before calling yylex. It + is no longer necessary to initialize it in the %initial-action. + +* Noteworthy changes in release 2.6.4 (2012-10-23) [stable] + + Bison 2.6.3's --version was incorrect. This release fixes this issue. + +* Noteworthy changes in release 2.6.3 (2012-10-22) [stable] + +** Bug fixes + + Bugs and portability issues in the test suite have been fixed. + + Some errors in translations have been addressed, and --help now directs + users to the appropriate place to report them. + + Stray Info files shipped by accident are removed. + + Incorrect definitions of YY_, issued by yacc.c when no parser header is + generated, are removed. + + All the generated headers are self-contained. + +** Header guards (yacc.c, glr.c, glr.cc) + + In order to avoid collisions, the header guards are now + YY___INCLUDED, instead of merely _. + For instance the header generated from + + %define api.prefix "calc" + %defines "lib/parse.h" + + will use YY_CALC_LIB_PARSE_H_INCLUDED as guard. + +** Fix compiler warnings in the generated parser (yacc.c, glr.c) + + The compilation of pure parsers (%define api.pure) can trigger GCC + warnings such as: + + input.c: In function 'yyparse': + input.c:1503:12: warning: 'yylval' may be used uninitialized in this + function [-Wmaybe-uninitialized] + *++yyvsp = yylval; + ^ + + This is now fixed; pragmas to avoid these warnings are no longer needed. + + Warnings from clang ("equality comparison with extraneous parentheses" and + "function declared 'noreturn' should not return") have also been + addressed. * Noteworthy changes in release 2.6.2 (2012-08-03) [stable] @@ -204,7 +486,7 @@ GNU Bison NEWS * Noteworthy changes in release 2.6 (2012-07-19) [stable] -** Future changes: +** Future changes The next major release of Bison will drop support for the following deprecated features. Please report disagreements to bug-bison@gnu.org. @@ -466,6 +748,7 @@ 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): @@ -982,6 +1265,7 @@ 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 @@ -995,6 +1279,7 @@ 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: @@ -2006,7 +2291,7 @@ along with this program. If not, see . LocalWords: Automake TMPDIR LESSEQ ylwrap endif yydebug YYTOKEN YYLSP ival hh LocalWords: extern YYTOKENTYPE TOKENTYPE yytokentype tokentype STYPE lval pdf LocalWords: lang yyoutput dvi html ps POSIX lvalp llocp Wother nterm arg init - LocalWords: TOK + LocalWords: TOK calc yyo fval Wconflicts Local Variables: mode: outline