X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/77714df234fec3610f18f873b569354599fac17d..5dac0025f6cef52c95cf1b8d04c5047980a73160:/NEWS diff --git a/NEWS b/NEWS index 50fb91ef..554f32ca 100644 --- a/NEWS +++ b/NEWS @@ -1,25 +1,142 @@ Bison News ---------- +Changes in version 1.75c: -Changes in version 1.49b: +* "parse error" -> "syntax error" + Bison now uniformly uses the term "syntax error"; formerly, the code + and manual sometimes used the term "parse error" instead. POSIX + requires "syntax error" in diagnostics, and it was thought better to + be consistent. + +* "parsing stack overflow..." -> "parser stack overflow" + GLR parsers now report "parser stack overflow" as per the Bison manual. + +* 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. -* Large grammars - Large grammars are now supported (large token numbers, large grammar - size (= sum of the LHS and RHS lengths), large LALR tables). +* 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 + token. Formerly, it popped the stack until it found a state that + allowed some non-error action other than a default reduction on the + error token. The new behavior has long been the documented behavior, + and has long been required by POSIX. For more details, please see + . + +* Traces + Popped tokens and nonterminals are now reported. + +* 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 @@ -30,6 +147,13 @@ Changes in version 1.49b: 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 @@ -52,26 +176,50 @@ Changes in version 1.49b: * 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 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 + produces additional information: + - itemset + complete the core item sets with their closure + - lookahead + explicitly associate lookaheads to items + - solved + describe shift/reduce conflicts solving. + 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 bar + %% + bar: '0' {} '0'; + + This is fixed. + +* GNU M4 is now required when using Bison. Changes in version 1.35, 2002-03-25: @@ -87,7 +235,6 @@ Changes in version 1.35, 2002-03-25: This kludge also addresses some C++ problems when the stack was extended. - Changes in version 1.34, 2002-03-12: @@ -213,8 +360,8 @@ Changes in version 1.31, 2002-01-14: 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