+ 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".
+
+** C++ skeleton improvements
+
+ 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).
+
+** Variable api.tokens.prefix
+
+ The variable api.tokens.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_"
+ %%
+ 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.namespace
+
+ The "namespace" variable is renamed "api.namespace". Backward
+ compatibility is ensured, but upgrading is recommended.
+
+** Variable parse.error
+
+ The variable error controls the verbosity of error messages. The
+ use of the %error-verbose directive is deprecated in favor of
+ %define parse.error "verbose".
+
+** Semantic predicates
+
+ 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
+ runtime expressions.
+
+* Noteworthy changes in release ?.? (????-??-??) [?]
+
+** Future changes:
+
+ The next major release will drop support for generating parsers in K&R C,
+ and remove the definition of yystype (removal announced since Bison
+ 1.875).
+
+** The generated header is included (yacc.c)
+
+ Instead of duplicating the content of the generated header (definition of
+ YYSTYPE, yyltype etc.), the generated parser now includes it, as was
+ already the case for GLR or C++ parsers.
+
+** Headers (yacc.c, glr.c, glr.cc)
+
+*** Guards
+
+ The generated headers are now guarded, as is already the case for C++
+ parsers (lalr1.cc). For intance, with --defines=foo.h:
+
+ #ifndef YY_FOO_H
+ # define YY_FOO_H
+ ...
+ #endif /* !YY_FOO_H */
+
+*** New declarations
+
+ The generated header now declares yydebug and yyparse. Both honor
+ --name-prefix=bar_, and yield
+
+ int bar_parse (void);
+
+ rather than
+
+ #define yyparse bar_parse
+ int yyparse (void);
+
+ in order to facilitate the inclusion of several parser headers inside a
+ single compilation unit.
+
+* Noteworthy changes in release 2.5.1 (2012-06-05) [stable]
+
+** Future changes:
+
+ The next major release will drop support for generating parsers in K&R C.
+
+** yacc.c: YYBACKUP works as expected.
+
+** glr.c improvements:
+
+*** Location support is eliminated when not requested:
+
+ GLR parsers used to include location-related code even when locations were
+ not requested, and therefore not even usable.
+
+*** __attribute__ is preserved:
+
+ __attribute__ is no longer disabled when __STRICT_ANSI__ is defined (i.e.,
+ when -std is passed to GCC).
+
+** lalr1.java: several fixes:
+
+ The Java parser no longer throws ArrayIndexOutOfBoundsException if the
+ first token leads to a syntax error. Some minor clean ups.
+
+** Changes for C++:
+
+*** C++11 compatibility:
+
+ C and C++ parsers use "nullptr" instead of "0" when __cplusplus is 201103L
+ or higher.
+
+*** Header guards
+
+ The header files such as "parser.hh", "location.hh", etc. used a constant
+ name for preprocessor guards, for instance:
+
+ #ifndef BISON_LOCATION_HH
+ # define BISON_LOCATION_HH
+ ...
+ #endif // !BISON_LOCATION_HH
+
+ The inclusion guard is now computed from "PREFIX/FILE-NAME", where lower
+ case characters are converted to upper case, and series of
+ non-alphanumerical characters are converted to an underscore.
+
+ With "bison -o lang++/parser.cc", "location.hh" would now include:
+
+ #ifndef YY_LANG_LOCATION_HH
+ # define YY_LANG_LOCATION_HH
+ ...
+ #endif // !YY_LANG_LOCATION_HH
+
+*** C++ locations:
+
+ The position and location constructors (and their initialize methods)
+ accept new arguments for line and column. Several issues in the
+ documentation were fixed.
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