*** 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 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
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].
+ to GCC, as [-Werror=CATEGORY].
For instance, where the previous version of Bison would report (and exit
with failure):
used by the scanner, or rejecting invalid combinations from a
factory invoked by the user actions).
+*** 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 (yy::parser::semantic_type *yylval);
+
+ This is has been fixed: yylval, ynerrs, yychar, and yylloc are now valid
+ identifiers for user-provided variables.
+
+** 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
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
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).
+
+** 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 <sval> exp
+ ^^^^^^
+ input.y:1.7-12: previous declaration
+ %type <ival> 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
All the generated headers are self-contained.
-** 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': <t3> != <t2>
- foo.y:4.13-27: previous declaration
-
- It is now:
-
- foo.y:5.10-25: result type clash on merge function 'merge': <t3> != <t2>
- foo.y:4.13-27: previous declaration
-
** Header guards (yacc.c, glr.c, glr.cc)
In order to avoid collisions, the header guards are now
will use YY_CALC_LIB_PARSE_H_INCLUDED as guard.
-** 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 rethrowing the exception.
-
- This feature is somewhat experimental. User feedback would be
- appreciated.
-
** Fix compiler warnings in the generated parser (yacc.c, glr.c)
The compilation of pure parsers (%define api.pure) can trigger GCC
"function declared 'noreturn' should not return") have also been
addressed.
-** New %define variable: api.location.type (glr.cc, lalr1.cc)
-
- 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).
-
* 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.
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):
The current Java interface is experimental and may evolve. More user
feedback will help to stabilize it.
+ Contributed by Paolo Bonzini.
** %language
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:
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 calc yyo fval
+ LocalWords: TOK calc yyo fval Wconflicts
Local Variables:
mode: outline
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