Bison News
----------
+Changes in version 1.75c:
-Changes in version 1.49b:
+* GLR and inline
+ Users of Bison have to decide how they handle the portability of the
+ C keyword `inline'.
+
+Changes in version 1.75b, 2002-11-13:
+
+* %destructor
+ It is now possible to reclaim the memory associated to symbols
+ discarded during error recovery. This feature is still experimental.
+
+* Bison now parses C99 lexical constructs like UCNs and
+ backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
+
+* --no-line works properly.
+
+* %error-verbose
+ This new directive is preferred over YYERROR_VERBOSE.
+
+* %lex-param, %parse-param
+ These new directives are preferred over PARSE_PARAM and LEX_PARAM.
+ In addition, they provide a means for yyerror to remain pure, and
+ to access to the current location.
+
+ #defining yyerror to steal internal variables is strongly
+ discouraged. It is not guaranteed to work for ever.
+
+* #line
+ Bison now recognizes #line in its input, and forwards them.
+
+* #line
+ File names are properly escaped. E.g. foo\bar.y give #line 123 "foo\\bar.y".
+
+Changes in version 1.75a, 2002-10-24:
+
+* Bison can no longer be built by a K&R C compiler; it requires C89 or
+ later to be built. This change originally took place a few versions
+ ago, but nobody noticed until we recently asked someone to try
+ building Bison with a K&R C compiler.
+
+Changes in version 1.75, 2002-10-14:
+
+* Bison should now work on 64-bit hosts.
+
+* Indonesian translation thanks to Tedi Heriyanto.
+
+* GLR parsers
+ Fix spurious parse errors.
+
+* Pure parsers
+ Some people redefine yyerror to steal yyparse' private variables.
+ Reenable this trick until an official feature replaces it.
+
+* Type Clashes
+ In agreement with POSIX and with other Yaccs, leaving a default
+ action is valid when $$ is untyped, and $1 typed:
+
+ untyped: ... typed;
+
+ but the converse remains an error:
+
+ typed: ... untyped;
+
+* Values of mid-rule actions
+ The following code:
+
+ foo: { ... } { $$ = $1; } ...
+
+ was incorrectly rejected: $1 is defined in the second mid-rule
+ action, and is equal to the $$ of the first mid-rule action.
+
+Changes in version 1.50, 2002-10-04:
+
+* GLR parsing
+ The declaration
+ %glr-parser
+ causes Bison to produce a Generalized LR (GLR) parser, capable of handling
+ almost any context-free grammar, ambiguous or not. The new declarations
+ %dprec and %merge on grammar rules allow parse-time resolution of
+ ambiguities. Contributed by Paul Hilfinger.
+
+ Unfortunately Bison 1.50 does not work properly on 64-bit hosts
+ like the Alpha, so please stick to 32-bit hosts for now.
+
+* Output Directory
+ When not in Yacc compatibility mode, when the output file was not
+ specified, running `bison foo/bar.y' created `foo/bar.c'. It
+ now creates `bar.c'.
* Undefined token
The undefined token was systematically mapped to 2 which prevented
- the use of 2 from the user. This is no longer the case.
+ the use of 2 by the user. This is no longer the case.
* Unknown token numbers
- If yylex returned a code out of range, yyparse could die. This is
+ If yylex returned an out of range value, yyparse could die. This is
no longer the case.
* Error token
- According to POSIX, the error token should be numbered as 256.
+ According to POSIX, the error token must be 256.
Bison extends this requirement by making it a preference: *if* the
user specified that one of her tokens is numbered 256, then error
will be mapped onto another number.
+* Verbose error messages
+ They no longer report `..., expecting error or...' for states where
+ error recovery is possible.
+
+* End token
+ Defaults to `$end' instead of `$'.
+
* Error recovery now conforms to documentation and to POSIX
When a Bison-generated parser encounters a syntax error, it now pops
the stack until it finds a state that allows shifting the error
* Traces
Popped tokens and nonterminals are now reported.
-* Large grammars
- Large grammars are now supported (large token numbers, large grammar
- size (= sum of the LHS and RHS lengths), large LALR tables).
+* Larger grammars
+ Larger grammars are now supported (larger token numbers, larger grammar
+ size (= sum of the LHS and RHS lengths), larger LALR tables).
+ Formerly, many of these numbers ran afoul of 16-bit limits;
+ now these limits are 32 bits on most hosts.
* Explicit initial rule
Bison used to play hacks with the initial rule, which the user does
Before, Bison reported the useless rules, but, although not used,
included them in the parsers. They are now actually removed.
+* Useless rules, useless nonterminals
+ They are now reported, as a warning, with their locations.
+
+* Rules never reduced
+ Rules that can never be reduced because of conflicts are now
+ reported.
+
* Incorrect `Token not used'
On a grammar such as
* Token end-of-file
The token end of file may be specified by the user, in which case,
the user symbol is used in the reports, the graphs, and the verbose
- error messages instead of `$', which remains being the defaults.
+ error messages instead of `$end', which remains being the default.
For instance
- %token YYEOF 0
+ %token MYEOF 0
or
- %token YYEOF 0 "end of file"
+ %token MYEOF 0 "end of file"
* Semantic parser
This old option, which has been broken for ages, is removed.
-* New translation
+* New translations
+ Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
Croatian, thanks to Denis Lackovic.
* Incorrect token definitions
- When fed with `%token 'a' "A"', Bison used to output `#define 'a' 65'.
+ When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
* Token definitions as enums
Tokens are output both as the traditional #define's, and, provided
the compiler supports ANSI C or is a C++ compiler, as enums.
- This helps debuggers producing symbols instead of values.
+ This lets debuggers display names instead of integers.
* Reports
In addition to --verbose, bison supports --report=THINGS, which
Bison used to systematically output this information on top of
the report. Solved conflicts are now attached to their states.
+* Type clashes
+ Previous versions don't complain when there is a type clash on
+ the default action if the rule has a mid-rule action, such as in:
+
+ %type <foo> bar
+ %%
+ bar: '0' {} '0';
+
+ This is fixed.
+
+* GNU M4 is now required when using Bison.
\f
Changes in version 1.35, 2002-03-25:
This kludge also addresses some C++ problems when the stack was
extended.
-
\f
Changes in version 1.34, 2002-03-12:
\f
Changes in version 1.30, 2001-10-26:
-* `--defines' and `--graph' have now an optionnal argument which is the
- output file name. `-d' and `-g' do not change, they do not take any
+* `--defines' and `--graph' have now an optional argument which is the
+ output file name. `-d' and `-g' do not change; they do not take any
argument.
* `%source_extension' and `%header_extension' are removed, failed
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