* Noteworthy changes in release ?.? (????-??-??) [?]
+** Bug fixes
+
+*** Location of errors
+
+ In C++ parsers, out-of-bounds errors can happen when a rule with an empty
+ ride-hand side raises a syntax error. The behavior of the default parser
+ (yacc.c) in such a condition was undefined.
+
+ Now all the parsers match the behavior of glr.c: @$ is used as the
+ location of the error. This handles gracefully rules with and without
+ rhs.
+
+* Noteworthy changes in release 3.0.4 (2015-01-23) [stable]
+
+** Bug fixes
+
+*** C++ with Variants (lalr1.cc)
+
+ Fix a compiler warning when no %destructor use $$.
+
+*** Test suites
+
+ Several portability issues in tests were fixed.
+
+* Noteworthy changes in release 3.0.3 (2015-01-15) [stable]
+
+** Bug fixes
+
+*** C++ with Variants (lalr1.cc)
+
+ Problems with %destructor and '%define parse.assert' have been fixed.
+
+*** Named %union support (yacc.c, glr.c)
+
+ Bison 3.0 introduced a regression on named %union such as
+
+ %union foo { int ival; };
+
+ The possibility to use a name was introduced "for Yacc compatibility".
+ It is however not required by POSIX Yacc, and its usefulness is not clear.
+
+*** %define api.value.type union with %defines (yacc.c, glr.c)
+
+ The C parsers were broken when %defines was used together with "%define
+ api.value.type union".
+
+*** Redeclarations are reported in proper order
+
+ On
+
+ %token FOO "foo"
+ %printer {} "foo"
+ %printer {} FOO
+
+ bison used to report:
+
+ /tmp/foo.yy:2.10-11: error: %printer redeclaration for FOO
+ %printer {} "foo"
+ ^^
+ /tmp/foo.yy:3.10-11: previous declaration
+ %printer {} FOO
+ ^^
+
+ Now, the "previous" declaration is always the first one.
+
+
+** Documentation
+
+ Bison now installs various files in its docdir (which defaults to
+ '/usr/local/share/doc/bison'), including the three fully blown examples
+ extracted from the documentation:
+
+ - rpcalc
+ Reverse polish calculator, a simple introductory example.
+ - mfcalc
+ Multi-function Calc, a calculator with memory and functions and located
+ error messages.
+ - calc++
+ a calculator in C++ using variant support and token constructors.
+
+* Noteworthy changes in release 3.0.2 (2013-12-05) [stable]
+
+** Bug fixes
+
+*** Generated source files when errors are reported
+
+ When warnings are issued and -Werror is set, bison would still generate
+ the source files (*.c, *.h...). As a consequence, some runs of "make"
+ could fail the first time, but not the second (as the files were generated
+ anyway).
+
+ This is fixed: bison no longer generates this source files, but, of
+ course, still produces the various reports (*.output, *.xml, etc.).
+
+*** %empty is used in reports
+
+ Empty right-hand sides are denoted by '%empty' in all the reports (text,
+ dot, XML and formats derived from it).
+
+*** YYERROR and variants
+
+ When C++ variant support is enabled, an error triggered via YYERROR, but
+ not caught via error recovery, resulted in a double deletion.
+
+* Noteworthy changes in release 3.0.1 (2013-11-12) [stable]
+
+** Bug fixes
+
+*** Errors in caret diagnostics
+
+ On some platforms, some errors could result in endless diagnostics.
+
+*** Fixes of the -Werror option
+
+ Options such as "-Werror -Wno-error=foo" were still turning "foo"
+ diagnostics into errors instead of warnings. This is fixed.
+
+ Actually, for consistency with GCC, "-Wno-error=foo -Werror" now also
+ leaves "foo" diagnostics as warnings. Similarly, with "-Werror=foo
+ -Wno-error", "foo" diagnostics are now errors.
+
+*** GLR Predicates
+
+ As demonstrated in the documentation, one can now leave spaces between
+ "%?" and its "{".
+
+*** Installation
+
+ The yacc.1 man page is no longer installed if --disable-yacc was
+ specified.
+
+*** Fixes in the test suite
+
+ Bugs and portability issues.
+
+* Noteworthy changes in release 3.0 (2013-07-25) [stable]
+
+** WARNING: Future backward-incompatibilities!
+
+ 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.
+
+** Backward incompatible changes
+
+*** Obsolete features
+
+ 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.
+
+ Missing semicolons at the end of actions are no longer added (as announced
+ in the release 2.5).
+
+*** Use of YACC='bison -y'
+
+ TL;DR: With Autoconf <= 2.69, pass -Wno-yacc to (AM_)YFLAGS if you use
+ Bison extensions.
+
+ Traditional Yacc generates 'y.tab.c' whatever the name of the input file.
+ Therefore Makefiles written for Yacc expect 'y.tab.c' (and possibly
+ 'y.tab.h' and 'y.outout') to be generated from 'foo.y'.
+
+ To this end, for ages, AC_PROG_YACC, Autoconf's macro to look for an
+ implementation of Yacc, was using Bison as 'bison -y'. While it does
+ ensure compatible output file names, it also enables warnings for
+ incompatibilities with POSIX Yacc. In other words, 'bison -y' triggers
+ warnings for Bison extensions.
+
+ Autoconf 2.70+ fixes this incompatibility by using YACC='bison -o y.tab.c'
+ (which also generates 'y.tab.h' and 'y.output' when needed).
+ Alternatively, disable Yacc warnings by passing '-Wno-yacc' to your Yacc
+ flags (YFLAGS, or AM_YFLAGS with Automake).
+
+** Bug fixes
+
+*** The epilogue is no longer affected by internal #defines (glr.c)
+
+ 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 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.
+
+*** Warnings about useless %pure-parser/%define api.pure are restored
+
+** Diagnostics reported by Bison
+
+ Most of these features were contributed by Théophile Ranquet and Victor
+ Santet.
+
+*** Carets
+
+ 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).
+
+ Some error messages that reproduced excerpts of the grammar are now using
+ the caret information only. For instance on:
+
+ %%
+ exp: 'a' | 'a';
+
+ Bison 2.7 reports:
+
+ in.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
+ in.y:2.12-14: warning: rule useless in parser due to conflicts: exp: 'a' [-Wother]
+
+ Now bison reports:
+
+ in.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
+ in.y:2.12-14: warning: rule useless in parser due to conflicts [-Wother]
+ exp: 'a' | 'a';
+ ^^^
+
+ and "bison -fno-caret" reports:
+
+ in.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
+ in.y:2.12-14: warning: rule useless in parser due to conflicts [-Wother]
+
+*** 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: <foo> != <bar> [-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.
+
+*** Useless semantic types
+
+ Bison now warns about useless (uninhabited) semantic types. Since
+ semantic types are not declared to Bison (they are defined in the opaque
+ %union structure), it is %printer/%destructor directives about useless
+ types that trigger the warning:
+
+ %token <type1> term
+ %type <type2> nterm
+ %printer {} <type1> <type3>
+ %destructor {} <type2> <type4>
+ %%
+ nterm: term { $$ = $1; };
+
+ 3.28-34: warning: type <type3> is used, but is not associated to any symbol
+ 4.28-34: warning: type <type4> is used, but is not associated to any symbol
+
+*** Undefined but unused symbols
+
+ Bison used to raise an error for undefined symbols that are not used in
+ the grammar. This is now only a warning.
+
+ %printer {} symbol1
+ %destructor {} symbol2
+ %type <type> symbol3
+ %%
+ exp: "a";
+
+*** Useless destructors or printers
+
+ Bison now warns about useless destructors or printers. In the following
+ example, the printer for <type1>, and the destructor for <type2> are
+ useless: all symbols of <type1> (token1) already have a printer, and all
+ symbols of type <type2> (token2) already have a destructor.
+
+ %token <type1> token1
+ <type2> token2
+ <type3> token3
+ <type4> token4
+ %printer {} token1 <type1> <type3>
+ %destructor {} token2 <type2> <type4>
+
+*** 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
+
+** Incompatibilities with POSIX Yacc
+
+ The 'yacc' category is no longer part of '-Wall', enable it explicitly
+ with '-Wyacc'.
+
+** Additional yylex/yyparse arguments
+
+ The new directive %param declares additional arguments to both yylex and
+ yyparse. The %lex-param, %parse-param, and %param directives support one
+ or more arguments. Instead of
+
+ %lex-param {arg1_type *arg1}
+ %lex-param {arg2_type *arg2}
+ %parse-param {arg1_type *arg1}
+ %parse-param {arg2_type *arg2}
+
+ one may now declare
+
+ %param {arg1_type *arg1} {arg2_type *arg2}
+
+** Types of values for %define variables
+
+ Bison used to make no difference between '%define foo bar' and '%define
+ foo "bar"'. The former is now called a 'keyword value', and the latter a
+ 'string value'. A third kind was added: 'code values', such as '%define
+ foo {bar}'.
+
+ Keyword variables are used for fixed value sets, e.g.,
+
+ %define lr.type lalr
+
+ Code variables are used for value in the target language, e.g.,
+
+ %define api.value.type {struct semantic_type}
+
+ String variables are used remaining cases, e.g. file names.
+
+** Variable api.token.prefix
+
+ 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.token.prefix {TOK_}
+ %%
+ start: FILE for ERROR;
+
+ will generate the definition of the symbols TOK_FILE, TOK_for, and
+ TOK_ERROR in the generated sources. In particular, the scanner must
+ use these prefixed token names, although the grammar itself still
+ uses the short names (as in the sample rule given above).
+
+** Variable api.value.type
+
+ This new %define variable supersedes the #define macro YYSTYPE. The use
+ of YYSTYPE is discouraged. In particular, #defining YYSTYPE *and* either
+ using %union or %defining api.value.type results in undefined behavior.
+
+ Either define api.value.type, or use "%union":
+
+ %union
+ {
+ int ival;
+ char *sval;
+ }
+ %token <ival> INT "integer"
+ %token <sval> STRING "string"
+ %printer { fprintf (yyo, "%d", $$); } <ival>
+ %destructor { free ($$); } <sval>
+
+ /* In yylex(). */
+ yylval.ival = 42; return INT;
+ yylval.sval = "42"; return STRING;
+
+ The %define variable api.value.type supports both keyword and code values.
+
+ The keyword value 'union' means that the user provides genuine types, not
+ union member names such as "ival" and "sval" above (WARNING: will fail if
+ -y/--yacc/%yacc is enabled).
+
+ %define api.value.type union
+ %token <int> INT "integer"
+ %token <char *> STRING "string"
+ %printer { fprintf (yyo, "%d", $$); } <int>
+ %destructor { free ($$); } <char *>
+
+ /* In yylex(). */
+ yylval.INT = 42; return INT;
+ yylval.STRING = "42"; return STRING;
+
+ The keyword value variant is somewhat equivalent, but for C++ special
+ provision is made to allow classes to be used (more about this below).
+
+ %define api.value.type variant
+ %token <int> INT "integer"
+ %token <std::string> STRING "string"
+
+ Code values (in braces) denote user defined types. This is where YYSTYPE
+ used to be used.
+
+ %code requires
+ {
+ struct my_value
+ {
+ enum
+ {
+ is_int, is_string
+ } kind;
+ union
+ {
+ int ival;
+ char *sval;
+ } u;
+ };
+ }
+ %define api.value.type {struct my_value}
+ %token <u.ival> INT "integer"
+ %token <u.sval> STRING "string"
+ %printer { fprintf (yyo, "%d", $$); } <u.ival>
+ %destructor { free ($$); } <u.sval>
+
+ /* In yylex(). */
+ yylval.u.ival = 42; return INT;
+ yylval.u.sval = "42"; return STRING;
+
+** Variable parse.error
+
+ This variable controls the verbosity of error messages. The use of the
+ %error-verbose directive is deprecated in favor of "%define parse.error
+ verbose".
+
+** 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
+
+** 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
+ in GLR parsers, rather than being deferred. The result is that they allow
+ the programmer to prune possible parses based on the values of run-time
+ expressions.
+
+** 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.
+
+** Tokens are numbered in their order of appearance
+
+ Contributed by Valentin Tolmer.
+
+ With '%token A B', A had a number less than the one of B. However,
+ precedence declarations used to generate a reversed order. This is now
+ fixed, and introducing tokens with any of %token, %left, %right,
+ %precedence, or %nonassoc yields the same result.
+
+ When mixing declarations of tokens with a litteral character (e.g., 'a')
+ or with an identifier (e.g., B) in a precedence declaration, Bison
+ numbered the litteral characters first. For example
+
+ %right A B 'c' 'd'
+
+ would lead to the tokens declared in this order: 'c' 'd' A B. Again, the
+ input order is now preserved.
+
+ These changes were made so that one can remove useless precedence and
+ associativity declarations (i.e., map %nonassoc, %left or %right to
+ %precedence, or to %token) and get exactly the same output.
+
+** Useless precedence and associativity
+
+ Contributed by Valentin Tolmer.
+
+ When developing and maintaining a grammar, useless associativity and
+ precedence directives are common. They can be a nuisance: new ambiguities
+ arising are sometimes masked because their conflicts are resolved due to
+ the extra precedence or associativity information. Furthermore, it can
+ hinder the comprehension of a new grammar: one will wonder about the role
+ of a precedence, where in fact it is useless. The following changes aim
+ at detecting and reporting these extra directives.
+
+*** Precedence warning category
+
+ A new category of warning, -Wprecedence, was introduced. It flags the
+ useless precedence and associativity directives.
+
+*** Useless associativity
+
+ Bison now warns about symbols with a declared associativity that is never
+ used to resolve conflicts. In that case, using %precedence is sufficient;
+ the parsing tables will remain unchanged. Solving these warnings may raise
+ useless precedence warnings, as the symbols no longer have associativity.
+ For example:
+
+ %left '+'
+ %left '*'
+ %%
+ exp:
+ "number"
+ | exp '+' "number"
+ | exp '*' exp
+ ;
+
+ will produce a
+
+ warning: useless associativity for '+', use %precedence [-Wprecedence]
+ %left '+'
+ ^^^
+
+*** Useless precedence
+
+ Bison now warns about symbols with a declared precedence and no declared
+ associativity (i.e., declared with %precedence), and whose precedence is
+ never used. In that case, the symbol can be safely declared with %token
+ instead, without modifying the parsing tables. For example:
+
+ %precedence '='
+ %%
+ exp: "var" '=' "number";
+
+ will produce a
+
+ warning: useless precedence for '=' [-Wprecedence]
+ %precedence '='
+ ^^^
+
+*** Useless precedence and associativity
+
+ In case of both useless precedence and associativity, the issue is flagged
+ as follows:
+
+ %nonassoc '='
+ %%
+ exp: "var" '=' "number";
+
+ The warning is:
+
+ warning: useless precedence and associativity for '=' [-Wprecedence]
+ %nonassoc '='
+ ^^^
+
+** Empty rules
+
+ With help from Joel E. Denny and Gabriel Rassoul.
+
+ Empty rules (i.e., with an empty right-hand side) can now be explicitly
+ marked by the new %empty directive. Using %empty on a non-empty rule is
+ an error. The new -Wempty-rule warning reports empty rules without
+ %empty. On the following grammar:
+
+ %%
+ s: a b c;
+ a: ;
+ b: %empty;
+ c: 'a' %empty;
+
+ bison reports:
+
+ 3.4-5: warning: empty rule without %empty [-Wempty-rule]
+ a: {}
+ ^^
+ 5.8-13: error: %empty on non-empty rule
+ c: 'a' %empty {};
+ ^^^^^^
+
+** Java skeleton improvements
+
+ 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".
+ Contributed by Paolo Bonzini.
+
+ The Java skeleton now supports push parsing.
+ Contributed by Dennis Heimbigner.
+
+** C++ skeletons improvements
+
+*** The parser header is no longer mandatory (lalr1.cc, glr.cc)
+
+ Using %defines is now optional. Without it, the needed support classes
+ are defined in the generated parser, instead of additional files (such as
+ location.hh, position.hh and stack.hh).
+
+*** Locations are no longer mandatory (lalr1.cc, glr.cc)
+
+ Both lalr1.cc and glr.cc no longer require %location.
+
+*** syntax_error exception (lalr1.cc)
+
+ The C++ parser features a syntax_error exception, which can be
+ thrown from the scanner or from user rules to raise syntax errors.
+ This facilitates reporting errors caught in sub-functions (e.g.,
+ rejecting too large integral literals from a conversion function
+ used by the scanner, or rejecting invalid combinations from a
+ factory invoked by the user actions).
+
+*** %define api.value.type variant
+
+ This is based on a submission from Michiel De Wilde. With help
+ from Théophile Ranquet.
+
+ In this mode, complex C++ objects can be used as semantic values. For
+ instance:
+
+ %token <::std::string> TEXT;
+ %token <int> NUMBER;
+ %token SEMICOLON ";"
+ %type <::std::string> item;
+ %type <::std::list<std::string>> list;
+ %%
+ result:
+ list { std::cout << $1 << std::endl; }
+ ;
+
+ list:
+ %empty { /* Generates an empty string list. */ }
+ | list item ";" { std::swap ($$, $1); $$.push_back ($2); }
+ ;
+
+ item:
+ TEXT { std::swap ($$, $1); }
+ | NUMBER { $$ = string_cast ($1); }
+ ;
+
+*** %define api.token.constructor
+
+ When variants are enabled, Bison can generate functions to build the
+ tokens. This guarantees that the token type (e.g., NUMBER) is consistent
+ with the semantic value (e.g., int):
+
+ parser::symbol_type yylex ()
+ {
+ parser::location_type loc = ...;
+ ...
+ return parser::make_TEXT ("Hello, world!", loc);
+ ...
+ return parser::make_NUMBER (42, loc);
+ ...
+ return parser::make_SEMICOLON (loc);
+ ...
+ }
+
+*** C++ locations
+
+ There are operator- and operator-= for 'location'. Negative line/column
+ increments can no longer underflow the resulting value.
+
+* Noteworthy changes in release 2.7.1 (2013-04-15) [stable]
+
+** Bug fixes
+
+*** Fix compiler attribute portability (yacc.c)
+
+ With locations enabled, __attribute__ was used unprotected.
+
+*** Fix some compiler warnings (lalr1.cc)
+
+* Noteworthy changes in release 2.7 (2012-12-12) [stable]
+
+** Bug fixes
+
+ Warnings about uninitialized yylloc in yyparse have been fixed.
+
+ Restored C90 compliance (yet no report was ever made).
+
+** Diagnostics are improved
+
+ Contributed by Théophile Ranquet.
+
+*** Changes in the format of error messages
+
+ This used to be the format of many error reports:
+
+ input.y:2.7-12: %type redeclaration for exp
+ input.y:1.7-12: previous declaration
+
+ It is now:
+
+ input.y:2.7-12: error: %type redeclaration for exp
+ input.y:1.7-12: previous declaration
+
+*** New format for error reports: carets
+
+ Caret errors have been added to Bison:
+
+ input.y:2.7-12: error: %type redeclaration for exp
+ %type <sval> exp
+ ^^^^^^
+ input.y:1.7-12: previous declaration
+ %type <ival> exp
+ ^^^^^^
+
+ or
+
+ input.y:3.20-23: error: ambiguous reference: '$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 behavior for now is still not to display these unless
+ explicitly 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
+
+ Contributed by Théophile Ranquet.
+
+ 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.
Other issues in the test suite have been addressed.
+ Null 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 (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):
These features are experimental. More user feedback will help to
stabilize them.
-** LAC (Lookahead Correction) for syntax error handling:
+** LAC (Lookahead Correction) for syntax error handling
+
+ Contributed by Joel E. Denny.
Canonical LR, IELR, and LALR can suffer from a couple of problems
upon encountering a syntax error. First, the parser might perform
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:
-----
-Copyright (C) 1995-2012 Free Software Foundation, Inc.
+Copyright (C) 1995-2015 Free Software Foundation, Inc.
This file is part of Bison, the GNU Parser Generator.
LocalWords: namespaces strerror const autoconfiguration Dconst Autoconf's FDL
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 calc yyo fval
+ LocalWords: lang yyoutput dvi html ps POSIX lvalp llocp Wother nterm arg init
+ LocalWords: TOK calc yyo fval Wconflicts parsers yystackp yyval yynerrs
+ LocalWords: Théophile Ranquet Santet fno fnone stype associativity Tolmer
+ LocalWords: Wprecedence Rassoul Wempty Paolo Bonzini parser's Michiel loc
+ LocalWords: redeclaration sval fcaret reentrant XSLT xsl Wmaybe yyvsp Tedi
+ LocalWords: pragmas noreturn untyped Rozenman unexpanded Wojciech Polak
+ LocalWords: Alexandre MERCHANTABILITY yytype
Local Variables:
mode: outline
projects / bison.git / blobdiff