Bison News
----------
+Changes in version 1.75c:
-Changes in version 1.49b:
+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
+ %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, runnning `bison foo/bar.y' created `foo/bar.c'. It
+ 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
* 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
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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