*** 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 explictly activated
- using the -W option, this is similar to what gcc 4.7 does.
+ 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 incompatiblities and S/R conflicts as
+ warnings related to POSIX Yacc incompatibilities and S/R conflicts as
errors (and only those):
$ bison -Werror=yacc,error=conflicts-sr input.y
Yacc-like behavior (e.g., always generate y.tab.c), but to report
incompatibilities as warnings: "-y -Wno-error=yacc".
-*** Warning categories are now displayed and prefix changes
+*** The display of warnings is now richer
- For instance:
+ The option that controls a given warning is now displayed:
- foo.y:4.6: warning: type clash on default action: <foo> != <bar> [-Wother]
+ foo.y:4.6: warning: type clash on default action: <foo> != <bar> [-Wother]
- In the case of warnings treated as errors, the suffix is displayed, in a
- manner similar to gcc, as [-Werror=CATEGORY]. Also, the prefix is changed
- from "warning: " to "error: ".
+ 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, considering the above change, an output for -Werror=other
- would have been:
+ 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 [-Wother]
+ input.y:1.1: warning: stray ',' treated as white space
- But it is actually:
+ it now reports:
- bison: warnings being treated as errors
input.y:1.1: error: stray ',' treated as white space [-Werror=other]
*** Deprecated constructs
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;
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
* Noteworthy changes in release ?.? (????-??-??) [?]
-** Bug fixes
+** %language is no longer an experimental feature.
- Bugs in the test suite 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.
- Some errors in translations have been addressed, and --help now directs
- users to the appropriate place to report them.
+** New value for %define variable: api.pure full
- Stray Info files shipped by accident are removed.
+ The %define variable api.pure requests a pure (reentrant) parser. However,
+ for historical reasons, using it in a location-tracking Yacc parser resulted
+ in an 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).
- Incorrect definitions of YY_, issued by yacc.c when no parser header is
- generated, are removed.
+ The use of "%define api.pure true" is deprecated in favor of this new
+ "%define api.pure full".
-** Changes in the format of errors and exceptions output
+** Changes in the format of error messages
This used to be the format of many error reports:
foo.y:5.10-25: result type clash on merge function 'merge': <t3> != <t2>
foo.y:4.13-27: previous declaration
+** 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.
+
+** 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.
+
+** 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.
+
+ Two nodes were added to the documentation: Xml and Graphviz.
+
+* Noteworthy changes in release ?.? (????-??-??) [?]
+
+** Bug fixes
+
+ Warnings about uninitialized yylloc in yyparse have been fixed.
+
+** Documentation
+
+ The sections about shift/reduce and reduce/reduce conflicts resolution
+ have been fixed and extended.
+
+* 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_<PREFIX>_<FILE>_INCLUDED, instead of merely <PREFIX>_<FILE>.
+ 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]
** Bug fixes
* 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.
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
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