Index: bison/src/bison/2.4.1/bison-2.4.1-src/NEWS |
=================================================================== |
--- bison/src/bison/2.4.1/bison-2.4.1-src/NEWS (revision 0) |
+++ bison/src/bison/2.4.1/bison-2.4.1-src/NEWS (revision 0) |
@@ -0,0 +1,1067 @@ |
+Bison News |
+---------- |
+ |
+* Changes in version 2.4.1 (2008-12-11): |
+ |
+** In the GLR defines file, unexpanded M4 macros in the yylval and yylloc |
+ declarations have been fixed. |
+ |
+** Temporary hack for adding a semicolon to the user action. |
+ |
+ Bison used to prepend a trailing semicolon at the end of the user |
+ action for reductions. This allowed actions such as |
+ |
+ exp: exp "+" exp { $$ = $1 + $3 }; |
+ |
+ instead of |
+ |
+ exp: exp "+" exp { $$ = $1 + $3; }; |
+ |
+ Some grammars still depend on this `feature'. Bison 2.4.1 restores |
+ the previous behavior in the case of C output (specifically, when |
+ neither %language or %skeleton or equivalent command-line options |
+ are used) to leave more time for grammars depending on the old |
+ behavior to be adjusted. Future releases of Bison will disable this |
+ feature. |
+ |
+** A few minor improvements to the Bison manual. |
+ |
+* Changes in version 2.4 (2008-11-02): |
+ |
+** %language is an experimental feature. |
+ |
+ We first introduced this feature in test release 2.3b as a cleaner |
+ alternative to %skeleton. Since then, we have discussed the possibility of |
+ modifying its effect on Bison's output file names. Thus, in this release, |
+ we consider %language to be an experimental feature that will likely evolve |
+ in future releases. |
+ |
+** Forward compatibility with GNU M4 has been improved. |
+ |
+** Several bugs in the C++ skeleton and the experimental Java skeleton have been |
+ fixed. |
+ |
+* Changes in version 2.3b (2008-05-27): |
+ |
+** The quotes around NAME that used to be required in the following directive |
+ are now deprecated: |
+ |
+ %define NAME "VALUE" |
+ |
+** The directive `%pure-parser' is now deprecated in favor of: |
+ |
+ %define api.pure |
+ |
+ which has the same effect except that Bison is more careful to warn about |
+ unreasonable usage in the latter case. |
+ |
+** Push Parsing |
+ |
+ Bison can now generate an LALR(1) parser in C with a push interface. That |
+ is, instead of invoking `yyparse', which pulls tokens from `yylex', you can |
+ push one token at a time to the parser using `yypush_parse', which will |
+ return to the caller after processing each token. By default, the push |
+ interface is disabled. Either of the following directives will enable it: |
+ |
+ %define api.push_pull "push" // Just push; does not require yylex. |
+ %define api.push_pull "both" // Push and pull; requires yylex. |
+ |
+ See the new section `A Push Parser' in the Bison manual for details. |
+ |
+ The current push parsing interface is experimental and may evolve. More user |
+ feedback will help to stabilize it. |
+ |
+** The -g and --graph options now output graphs in Graphviz DOT format, |
+ not VCG format. Like --graph, -g now also takes an optional FILE argument |
+ and thus cannot be bundled with other short options. |
+ |
+** Java |
+ |
+ Bison can now generate an LALR(1) parser in Java. The skeleton is |
+ `data/lalr1.java'. Consider using the new %language directive instead of |
+ %skeleton to select it. |
+ |
+ See the new section `Java Parsers' in the Bison manual for details. |
+ |
+ The current Java interface is experimental and may evolve. More user |
+ feedback will help to stabilize it. |
+ |
+** %language |
+ |
+ This new directive specifies the programming language of the generated |
+ parser, which can be C (the default), C++, or Java. Besides the skeleton |
+ that Bison uses, the directive affects the names of the generated files if |
+ the grammar file's name ends in ".y". |
+ |
+** XML Automaton Report |
+ |
+ 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. |
+ |
+** The grammar file may now specify the name of the parser header file using |
+ %defines. For example: |
+ |
+ %defines "parser.h" |
+ |
+** When reporting useless rules, useless nonterminals, and unused terminals, |
+ Bison now employs the terms "useless in grammar" instead of "useless", |
+ "useless in parser" instead of "never reduced", and "unused in grammar" |
+ instead of "unused". |
+ |
+** Unreachable State Removal |
+ |
+ Previously, Bison sometimes generated parser tables containing unreachable |
+ states. A state can become unreachable during conflict resolution if Bison |
+ disables a shift action leading to it from a predecessor state. Bison now: |
+ |
+ 1. Removes unreachable states. |
+ |
+ 2. Does not report any conflicts that appeared in unreachable states. |
+ WARNING: As a result, you may need to update %expect and %expect-rr |
+ directives in existing grammar files. |
+ |
+ 3. For any rule used only in such states, Bison now reports the rule as |
+ "useless in parser due to conflicts". |
+ |
+ This feature can be disabled with the following directive: |
+ |
+ %define lr.keep_unreachable_states |
+ |
+ See the %define entry in the `Bison Declaration Summary' in the Bison manual |
+ for further discussion. |
+ |
+** Lookahead Set Correction in the `.output' Report |
+ |
+ When instructed to generate a `.output' file including lookahead sets |
+ (using `--report=lookahead', for example), Bison now prints each reduction's |
+ lookahead set only next to the associated state's one item that (1) is |
+ associated with the same rule as the reduction and (2) has its dot at the end |
+ of its RHS. Previously, Bison also erroneously printed the lookahead set |
+ next to all of the state's other items associated with the same rule. This |
+ bug affected only the `.output' file and not the generated parser source |
+ code. |
+ |
+** --report-file=FILE is a new option to override the default `.output' file |
+ name. |
+ |
+** The `=' that used to be required in the following directives is now |
+ deprecated: |
+ |
+ %file-prefix "parser" |
+ %name-prefix "c_" |
+ %output "parser.c" |
+ |
+** An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}' |
+ |
+ Bison 2.3a provided a new set of directives as a more flexible alternative to |
+ the traditional Yacc prologue blocks. Those have now been consolidated into |
+ a single %code directive with an optional qualifier field, which identifies |
+ the purpose of the code and thus the location(s) where Bison should generate |
+ it: |
+ |
+ 1. `%code {CODE}' replaces `%after-header {CODE}' |
+ 2. `%code requires {CODE}' replaces `%start-header {CODE}' |
+ 3. `%code provides {CODE}' replaces `%end-header {CODE}' |
+ 4. `%code top {CODE}' replaces `%before-header {CODE}' |
+ |
+ See the %code entries in section `Bison Declaration Summary' in the Bison |
+ manual for a summary of the new functionality. See the new section `Prologue |
+ Alternatives' for a detailed discussion including the advantages of %code |
+ over the traditional Yacc prologues. |
+ |
+ The prologue alternatives are experimental. More user feedback will help to |
+ determine whether they should become permanent features. |
+ |
+** Revised warning: unset or unused mid-rule values |
+ |
+ Since Bison 2.2, Bison has warned about mid-rule values that are set but not |
+ used within any of the actions of the parent rule. For example, Bison warns |
+ about unused $2 in: |
+ |
+ exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; }; |
+ |
+ Now, Bison also warns about mid-rule values that are used but not set. For |
+ example, Bison warns about unset $$ in the mid-rule action in: |
+ |
+ exp: '1' { $1 = 1; } '+' exp { $$ = $2 + $4; }; |
+ |
+ However, Bison now disables both of these warnings by default since they |
+ sometimes prove to be false alarms in existing grammars employing the Yacc |
+ constructs $0 or $-N (where N is some positive integer). |
+ |
+ To enable these warnings, specify the option `--warnings=midrule-values' or |
+ `-W', which is a synonym for `--warnings=all'. |
+ |
+** Default %destructor or %printer with `<*>' or `<>' |
+ |
+ Bison now recognizes two separate kinds of default %destructor's and |
+ %printer's: |
+ |
+ 1. Place `<*>' in a %destructor/%printer symbol list to define a default |
+ %destructor/%printer for all grammar symbols for which you have formally |
+ declared semantic type tags. |
+ |
+ 2. Place `<>' in a %destructor/%printer symbol list to define a default |
+ %destructor/%printer for all grammar symbols without declared semantic |
+ type tags. |
+ |
+ Bison no longer supports the `%symbol-default' notation from Bison 2.3a. |
+ `<*>' and `<>' combined achieve the same effect with one exception: Bison no |
+ longer applies any %destructor to a mid-rule value if that mid-rule value is |
+ not actually ever referenced using either $$ or $n in a semantic action. |
+ |
+ The default %destructor's and %printer's are experimental. More user |
+ feedback will help to determine whether they should become permanent |
+ features. |
+ |
+ See the section `Freeing Discarded Symbols' in the Bison manual for further |
+ details. |
+ |
+** %left, %right, and %nonassoc can now declare token numbers. This is required |
+ by POSIX. However, see the end of section `Operator Precedence' in the Bison |
+ manual for a caveat concerning the treatment of literal strings. |
+ |
+** The nonfunctional --no-parser, -n, and %no-parser options have been |
+ completely removed from Bison. |
+ |
+* Changes in version 2.3a, 2006-09-13: |
+ |
+** Instead of %union, you can define and use your own union type |
+ YYSTYPE if your grammar contains at least one <type> tag. |
+ Your YYSTYPE need not be a macro; it can be a typedef. |
+ This change is for compatibility with other Yacc implementations, |
+ and is required by POSIX. |
+ |
+** Locations columns and lines start at 1. |
+ In accordance with the GNU Coding Standards and Emacs. |
+ |
+** You may now declare per-type and default %destructor's and %printer's: |
+ |
+ For example: |
+ |
+ %union { char *string; } |
+ %token <string> STRING1 |
+ %token <string> STRING2 |
+ %type <string> string1 |
+ %type <string> string2 |
+ %union { char character; } |
+ %token <character> CHR |
+ %type <character> chr |
+ %destructor { free ($$); } %symbol-default |
+ %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1 |
+ %destructor { } <character> |
+ |
+ guarantees that, when the parser discards any user-defined symbol that has a |
+ semantic type tag other than `<character>', it passes its semantic value to |
+ `free'. However, when the parser discards a `STRING1' or a `string1', it |
+ also prints its line number to `stdout'. It performs only the second |
+ `%destructor' in this case, so it invokes `free' only once. |
+ |
+ [Although we failed to mention this here in the 2.3a release, the default |
+ %destructor's and %printer's were experimental, and they were rewritten in |
+ future versions.] |
+ |
+** Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y', |
+ `--yacc', or `%yacc'), Bison no longer generates #define statements for |
+ associating token numbers with token names. Removing the #define statements |
+ helps to sanitize the global namespace during preprocessing, but POSIX Yacc |
+ requires them. Bison still generates an enum for token names in all cases. |
+ |
+** Handling of traditional Yacc prologue blocks is now more consistent but |
+ potentially incompatible with previous releases of Bison. |
+ |
+ As before, you declare prologue blocks in your grammar file with the |
+ `%{ ... %}' syntax. To generate the pre-prologue, Bison concatenates all |
+ prologue blocks that you've declared before the first %union. To generate |
+ the post-prologue, Bison concatenates all prologue blocks that you've |
+ declared after the first %union. |
+ |
+ Previous releases of Bison inserted the pre-prologue into both the header |
+ file and the code file in all cases except for LALR(1) parsers in C. In the |
+ latter case, Bison inserted it only into the code file. For parsers in C++, |
+ the point of insertion was before any token definitions (which associate |
+ token numbers with names). For parsers in C, the point of insertion was |
+ after the token definitions. |
+ |
+ Now, Bison never inserts the pre-prologue into the header file. In the code |
+ file, it always inserts it before the token definitions. |
+ |
+** Bison now provides a more flexible alternative to the traditional Yacc |
+ prologue blocks: %before-header, %start-header, %end-header, and |
+ %after-header. |
+ |
+ For example, the following declaration order in the grammar file reflects the |
+ order in which Bison will output these code blocks. However, you are free to |
+ declare these code blocks in your grammar file in whatever order is most |
+ convenient for you: |
+ |
+ %before-header { |
+ /* Bison treats this block like a pre-prologue block: it inserts it into |
+ * the code file before the contents of the header file. It does *not* |
+ * insert it into the header file. This is a good place to put |
+ * #include's that you want at the top of your code file. A common |
+ * example is `#include "system.h"'. */ |
+ } |
+ %start-header { |
+ /* Bison inserts this block into both the header file and the code file. |
+ * In both files, the point of insertion is before any Bison-generated |
+ * token, semantic type, location type, and class definitions. This is a |
+ * good place to define %union dependencies, for example. */ |
+ } |
+ %union { |
+ /* Unlike the traditional Yacc prologue blocks, the output order for the |
+ * new %*-header blocks is not affected by their declaration position |
+ * relative to any %union in the grammar file. */ |
+ } |
+ %end-header { |
+ /* Bison inserts this block into both the header file and the code file. |
+ * In both files, the point of insertion is after the Bison-generated |
+ * definitions. This is a good place to declare or define public |
+ * functions or data structures that depend on the Bison-generated |
+ * definitions. */ |
+ } |
+ %after-header { |
+ /* Bison treats this block like a post-prologue block: it inserts it into |
+ * the code file after the contents of the header file. It does *not* |
+ * insert it into the header file. This is a good place to declare or |
+ * define internal functions or data structures that depend on the |
+ * Bison-generated definitions. */ |
+ } |
+ |
+ If you have multiple occurrences of any one of the above declarations, Bison |
+ will concatenate the contents in declaration order. |
+ |
+ [Although we failed to mention this here in the 2.3a release, the prologue |
+ alternatives were experimental, and they were rewritten in future versions.] |
+ |
+** The option `--report=look-ahead' has been changed to `--report=lookahead'. |
+ The old spelling still works, but is not documented and may be removed |
+ in a future release. |
+ |
+* Changes in version 2.3, 2006-06-05: |
+ |
+** GLR grammars should now use `YYRECOVERING ()' instead of `YYRECOVERING', |
+ for compatibility with LALR(1) grammars. |
+ |
+** It is now documented that any definition of YYSTYPE or YYLTYPE should |
+ be to a type name that does not contain parentheses or brackets. |
+ |
+* Changes in version 2.2, 2006-05-19: |
+ |
+** The distribution terms for all Bison-generated parsers now permit |
+ using the parsers in nonfree programs. Previously, this permission |
+ was granted only for Bison-generated LALR(1) parsers in C. |
+ |
+** %name-prefix changes the namespace name in C++ outputs. |
+ |
+** The C++ parsers export their token_type. |
+ |
+** Bison now allows multiple %union declarations, and concatenates |
+ their contents together. |
+ |
+** New warning: unused values |
+ Right-hand side symbols whose values are not used are reported, |
+ if the symbols have destructors. For instance: |
+ |
+ exp: exp "?" exp ":" exp { $1 ? $1 : $3; } |
+ | exp "+" exp |
+ ; |
+ |
+ will trigger a warning about $$ and $5 in the first rule, and $3 in |
+ the second ($1 is copied to $$ by the default rule). This example |
+ most likely contains three errors, and could be rewritten as: |
+ |
+ exp: exp "?" exp ":" exp |
+ { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); } |
+ | exp "+" exp |
+ { $$ = $1 ? $1 : $3; if ($1) free ($3); } |
+ ; |
+ |
+ However, if the original actions were really intended, memory leaks |
+ and all, the warnings can be suppressed by letting Bison believe the |
+ values are used, e.g.: |
+ |
+ exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); } |
+ | exp "+" exp { $$ = $1; (void) $3; } |
+ ; |
+ |
+ If there are mid-rule actions, the warning is issued if no action |
+ uses it. The following triggers no warning: $1 and $3 are used. |
+ |
+ exp: exp { push ($1); } '+' exp { push ($3); sum (); }; |
+ |
+ The warning is intended to help catching lost values and memory leaks. |
+ If a value is ignored, its associated memory typically is not reclaimed. |
+ |
+** %destructor vs. YYABORT, YYACCEPT, and YYERROR. |
+ Destructors are now called when user code invokes YYABORT, YYACCEPT, |
+ and YYERROR, for all objects on the stack, other than objects |
+ corresponding to the right-hand side of the current rule. |
+ |
+** %expect, %expect-rr |
+ Incorrect numbers of expected conflicts are now actual errors, |
+ instead of warnings. |
+ |
+** GLR, YACC parsers. |
+ The %parse-params are available in the destructors (and the |
+ experimental printers) as per the documentation. |
+ |
+** Bison now warns if it finds a stray `$' or `@' in an action. |
+ |
+** %require "VERSION" |
+ This specifies that the grammar file depends on features implemented |
+ in Bison version VERSION or higher. |
+ |
+** lalr1.cc: The token and value types are now class members. |
+ The tokens were defined as free form enums and cpp macros. YYSTYPE |
+ was defined as a free form union. They are now class members: |
+ tokens are enumerations of the `yy::parser::token' struct, and the |
+ semantic values have the `yy::parser::semantic_type' type. |
+ |
+ If you do not want or can update to this scheme, the directive |
+ `%define "global_tokens_and_yystype" "1"' triggers the global |
+ definition of tokens and YYSTYPE. This change is suitable both |
+ for previous releases of Bison, and this one. |
+ |
+ If you wish to update, then make sure older version of Bison will |
+ fail using `%require "2.2"'. |
+ |
+** DJGPP support added. |
+ |
+* Changes in version 2.1, 2005-09-16: |
+ |
+** The C++ lalr1.cc skeleton supports %lex-param. |
+ |
+** Bison-generated parsers now support the translation of diagnostics like |
+ "syntax error" into languages other than English. The default |
+ language is still English. For details, please see the new |
+ Internationalization section of the Bison manual. Software |
+ distributors should also see the new PACKAGING file. Thanks to |
+ Bruno Haible for this new feature. |
+ |
+** Wording in the Bison-generated parsers has been changed slightly to |
+ simplify translation. In particular, the message "memory exhausted" |
+ has replaced "parser stack overflow", as the old message was not |
+ always accurate for modern Bison-generated parsers. |
+ |
+** Destructors are now called when the parser aborts, for all symbols left |
+ behind on the stack. Also, the start symbol is now destroyed after a |
+ successful parse. In both cases, the behavior was formerly inconsistent. |
+ |
+** When generating verbose diagnostics, Bison-generated parsers no longer |
+ quote the literal strings associated with tokens. For example, for |
+ a syntax error associated with '%token NUM "number"' they might |
+ print 'syntax error, unexpected number' instead of 'syntax error, |
+ unexpected "number"'. |
+ |
+* Changes in version 2.0, 2004-12-25: |
+ |
+** Possibly-incompatible changes |
+ |
+ - Bison-generated parsers no longer default to using the alloca function |
+ (when available) to extend the parser stack, due to widespread |
+ problems in unchecked stack-overflow detection. You can "#define |
+ YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read |
+ the manual to determine safe values for YYMAXDEPTH in that case. |
+ |
+ - Error token location. |
+ During error recovery, the location of the syntax error is updated |
+ to cover the whole sequence covered by the error token: it includes |
+ the shifted symbols thrown away during the first part of the error |
+ recovery, and the lookahead rejected during the second part. |
+ |
+ - Semicolon changes: |
+ . Stray semicolons are no longer allowed at the start of a grammar. |
+ . Semicolons are now required after in-grammar declarations. |
+ |
+ - Unescaped newlines are no longer allowed in character constants or |
+ string literals. They were never portable, and GCC 3.4.0 has |
+ dropped support for them. Better diagnostics are now generated if |
+ forget a closing quote. |
+ |
+ - NUL bytes are no longer allowed in Bison string literals, unfortunately. |
+ |
+** New features |
+ |
+ - GLR grammars now support locations. |
+ |
+ - New directive: %initial-action. |
+ This directive allows the user to run arbitrary code (including |
+ initializing @$) from yyparse before parsing starts. |
+ |
+ - A new directive "%expect-rr N" specifies the expected number of |
+ reduce/reduce conflicts in GLR parsers. |
+ |
+ - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'. |
+ This is a GNU extension. |
+ |
+ - The option `--report=lookahead' was changed to `--report=look-ahead'. |
+ [However, this was changed back after 2.3.] |
+ |
+ - Experimental %destructor support has been added to lalr1.cc. |
+ |
+ - New configure option --disable-yacc, to disable installation of the |
+ yacc command and -ly library introduced in 1.875 for POSIX conformance. |
+ |
+** Bug fixes |
+ |
+ - For now, %expect-count violations are now just warnings, not errors. |
+ This is for compatibility with Bison 1.75 and earlier (when there are |
+ reduce/reduce conflicts) and with Bison 1.30 and earlier (when there |
+ are too many or too few shift/reduce conflicts). However, in future |
+ versions of Bison we plan to improve the %expect machinery so that |
+ these violations will become errors again. |
+ |
+ - Within Bison itself, numbers (e.g., goto numbers) are no longer |
+ arbitrarily limited to 16-bit counts. |
+ |
+ - Semicolons are now allowed before "|" in grammar rules, as POSIX requires. |
+ |
+* Changes in version 1.875, 2003-01-01: |
+ |
+** The documentation license has been upgraded to version 1.2 |
+ of the GNU Free Documentation License. |
+ |
+** syntax error processing |
+ |
+ - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error |
+ locations too. This fixes bugs in error-location computation. |
+ |
+ - %destructor |
+ It is now possible to reclaim the memory associated to symbols |
+ discarded during error recovery. This feature is still experimental. |
+ |
+ - %error-verbose |
+ This new directive is preferred over YYERROR_VERBOSE. |
+ |
+ - #defining yyerror to steal internal variables is discouraged. |
+ It is not guaranteed to work forever. |
+ |
+** POSIX conformance |
+ |
+ - Semicolons are once again optional at the end of grammar rules. |
+ This reverts to the behavior of Bison 1.33 and earlier, and improves |
+ compatibility with Yacc. |
+ |
+ - `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. |
+ |
+ - The documentation now emphasizes that yylex and yyerror must be |
+ declared before use. C99 requires this. |
+ |
+ - Bison now parses C99 lexical constructs like UCNs and |
+ backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires. |
+ |
+ - File names are properly escaped in C output. E.g., foo\bar.y is |
+ output as "foo\\bar.y". |
+ |
+ - Yacc command and library now available |
+ The Bison distribution now installs a `yacc' command, as POSIX requires. |
+ Also, Bison now installs a small library liby.a containing |
+ implementations of Yacc-compatible yyerror and main functions. |
+ This library is normally not useful, but POSIX requires it. |
+ |
+ - Type clashes now generate warnings, not errors. |
+ |
+ - If the user does not define YYSTYPE as a macro, Bison now declares it |
+ using typedef instead of defining it as a macro. |
+ For consistency, YYLTYPE is also declared instead of defined. |
+ |
+** Other compatibility issues |
+ |
+ - %union directives can now have a tag before the `{', e.g., the |
+ directive `%union foo {...}' now generates the C code |
+ `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility. |
+ The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc. |
+ For consistency, YYLTYPE's struct tag is now `YYLTYPE' not `yyltype'. |
+ This is for compatibility with both Yacc and Bison 1.35. |
+ |
+ - `;' is output before the terminating `}' of an action, for |
+ compatibility with Bison 1.35. |
+ |
+ - Bison now uses a Yacc-style format for conflict reports, e.g., |
+ `conflicts: 2 shift/reduce, 1 reduce/reduce'. |
+ |
+ - `yystype' and `yyltype' are now obsolescent macros instead of being |
+ typedefs or tags; they are no longer documented and are planned to be |
+ withdrawn in a future release. |
+ |
+** GLR parser notes |
+ |
+ - GLR and inline |
+ Users of Bison have to decide how they handle the portability of the |
+ C keyword `inline'. |
+ |
+ - `parsing stack overflow...' -> `parser stack overflow' |
+ GLR parsers now report `parser stack overflow' as per the Bison manual. |
+ |
+** Bison now warns if it detects conflicting outputs to the same file, |
+ e.g., it generates a warning for `bison -d -o foo.h foo.y' since |
+ that command outputs both code and header to foo.h. |
+ |
+** #line in output files |
+ - --no-line works properly. |
+ |
+** 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 by the user. This is no longer the case. |
+ |
+** Unknown token numbers |
+ 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 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 |
+ 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 |
+ Paul Eggert, "Reductions during Bison error handling" (2002-05-20) |
+ <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>. |
+ |
+** 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 |
+ not write. It is now explicit, and visible in the reports and |
+ graphs as rule 0. |
+ |
+** Useless rules |
+ 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 useless useful |
+ %% |
+ exp: '0' %prec useful; |
+ |
+ where a token was used to set the precedence of the last rule, |
+ bison reported both `useful' and `useless' as useless tokens. |
+ |
+** Revert the C++ namespace changes introduced in 1.31 |
+ as they caused too many portability hassles. |
+ |
+** Default locations |
+ By an accident of design, the default computation of @$ was |
+ performed after another default computation was performed: @$ = @1. |
+ The latter is now removed: YYLLOC_DEFAULT is fully responsible of |
+ the computation of @$. |
+ |
+** Token end-of-file |
+ The token end of file may be specified by the user, in which case, |
+ the user symbol is used in the reports, the graphs, and the verbose |
+ error messages instead of `$end', which remains being the default. |
+ For instance |
+ %token MYEOF 0 |
+ or |
+ %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 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 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 [changed to `look-ahead' in 1.875e through 2.3, but changed back] |
+ explicitly associate lookahead tokens 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 <foo> bar |
+ %% |
+ bar: '0' {} '0'; |
+ |
+ This is fixed. |
+ |
+** GNU M4 is now required when using Bison. |
+ |
+* Changes in version 1.35, 2002-03-25: |
+ |
+** C Skeleton |
+ Some projects use Bison's C parser with C++ compilers, and define |
+ YYSTYPE as a class. The recent adjustment of C parsers for data |
+ alignment and 64 bit architectures made this impossible. |
+ |
+ Because for the time being no real solution for C++ parser |
+ generation exists, kludges were implemented in the parser to |
+ maintain this use. In the future, when Bison has C++ parsers, this |
+ kludge will be disabled. |
+ |
+ This kludge also addresses some C++ problems when the stack was |
+ extended. |
+ |
+* Changes in version 1.34, 2002-03-12: |
+ |
+** File name clashes are detected |
+ $ bison foo.y -d -o foo.x |
+ fatal error: header and parser would both be named `foo.x' |
+ |
+** A missing `;' at the end of a rule triggers a warning |
+ In accordance with POSIX, and in agreement with other |
+ Yacc implementations, Bison will mandate this semicolon in the near |
+ future. This eases the implementation of a Bison parser of Bison |
+ grammars by making this grammar LALR(1) instead of LR(2). To |
+ facilitate the transition, this release introduces a warning. |
+ |
+** Revert the C++ namespace changes introduced in 1.31, as they caused too |
+ many portability hassles. |
+ |
+** DJGPP support added. |
+ |
+** Fix test suite portability problems. |
+ |
+* Changes in version 1.33, 2002-02-07: |
+ |
+** Fix C++ issues |
+ Groff could not be compiled for the definition of size_t was lacking |
+ under some conditions. |
+ |
+** Catch invalid @n |
+ As is done with $n. |
+ |
+* Changes in version 1.32, 2002-01-23: |
+ |
+** Fix Yacc output file names |
+ |
+** Portability fixes |
+ |
+** Italian, Dutch translations |
+ |
+* Changes in version 1.31, 2002-01-14: |
+ |
+** Many Bug Fixes |
+ |
+** GNU Gettext and %expect |
+ GNU Gettext asserts 10 s/r conflicts, but there are 7. Now that |
+ Bison dies on incorrect %expectations, we fear there will be |
+ too many bug reports for Gettext, so _for the time being_, %expect |
+ does not trigger an error when the input file is named `plural.y'. |
+ |
+** Use of alloca in parsers |
+ If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use |
+ malloc exclusively. Since 1.29, but was not NEWS'ed. |
+ |
+ alloca is used only when compiled with GCC, to avoid portability |
+ problems as on AIX. |
+ |
+** yyparse now returns 2 if memory is exhausted; formerly it dumped core. |
+ |
+** When the generated parser lacks debugging code, YYDEBUG is now 0 |
+ (as POSIX requires) instead of being undefined. |
+ |
+** User Actions |
+ Bison has always permitted actions such as { $$ = $1 }: it adds the |
+ ending semicolon. Now if in Yacc compatibility mode, the semicolon |
+ is no longer output: one has to write { $$ = $1; }. |
+ |
+** Better C++ compliance |
+ The output parsers try to respect C++ namespaces. |
+ [This turned out to be a failed experiment, and it was reverted later.] |
+ |
+** Reduced Grammars |
+ Fixed bugs when reporting useless nonterminals. |
+ |
+** 64 bit hosts |
+ The parsers work properly on 64 bit hosts. |
+ |
+** Error messages |
+ Some calls to strerror resulted in scrambled or missing error messages. |
+ |
+** %expect |
+ When the number of shift/reduce conflicts is correct, don't issue |
+ any warning. |
+ |
+** The verbose report includes the rule line numbers. |
+ |
+** Rule line numbers are fixed in traces. |
+ |
+** Swedish translation |
+ |
+** Parse errors |
+ Verbose parse error messages from the parsers are better looking. |
+ Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'('' |
+ Now: parse error: unexpected '/', expecting "number" or '-' or '(' |
+ |
+** Fixed parser memory leaks. |
+ When the generated parser was using malloc to extend its stacks, the |
+ previous allocations were not freed. |
+ |
+** Fixed verbose output file. |
+ Some newlines were missing. |
+ Some conflicts in state descriptions were missing. |
+ |
+** Fixed conflict report. |
+ Option -v was needed to get the result. |
+ |
+** %expect |
+ Was not used. |
+ Mismatches are errors, not warnings. |
+ |
+** Fixed incorrect processing of some invalid input. |
+ |
+** Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H. |
+ |
+** Fixed some typos in the documentation. |
+ |
+** %token MY_EOF 0 is supported. |
+ Before, MY_EOF was silently renumbered as 257. |
+ |
+** doc/refcard.tex is updated. |
+ |
+** %output, %file-prefix, %name-prefix. |
+ New. |
+ |
+** --output |
+ New, aliasing `--output-file'. |
+ |
+* Changes in version 1.30, 2001-10-26: |
+ |
+** `--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 |
+ experiment. |
+ |
+** Portability fixes. |
+ |
+* Changes in version 1.29, 2001-09-07: |
+ |
+** The output file does not define const, as this caused problems when used |
+ with common autoconfiguration schemes. If you still use ancient compilers |
+ that lack const, compile with the equivalent of the C compiler option |
+ `-Dconst='. autoconf's AC_C_CONST macro provides one way to do this. |
+ |
+** Added `-g' and `--graph'. |
+ |
+** The Bison manual is now distributed under the terms of the GNU FDL. |
+ |
+** The input and the output files has automatically a similar extension. |
+ |
+** Russian translation added. |
+ |
+** NLS support updated; should hopefully be less troublesome. |
+ |
+** Added the old Bison reference card. |
+ |
+** Added `--locations' and `%locations'. |
+ |
+** Added `-S' and `--skeleton'. |
+ |
+** `%raw', `-r', `--raw' is disabled. |
+ |
+** Special characters are escaped when output. This solves the problems |
+ of the #line lines with path names including backslashes. |
+ |
+** New directives. |
+ `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose', |
+ `%debug', `%source_extension' and `%header_extension'. |
+ |
+** @$ |
+ Automatic location tracking. |
+ |
+* Changes in version 1.28, 1999-07-06: |
+ |
+** Should compile better now with K&R compilers. |
+ |
+** Added NLS. |
+ |
+** Fixed a problem with escaping the double quote character. |
+ |
+** There is now a FAQ. |
+ |
+* Changes in version 1.27: |
+ |
+** The make rule which prevented bison.simple from being created on |
+ some systems has been fixed. |
+ |
+* Changes in version 1.26: |
+ |
+** Bison now uses automake. |
+ |
+** New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>. |
+ |
+** Token numbers now start at 257 as previously documented, not 258. |
+ |
+** Bison honors the TMPDIR environment variable. |
+ |
+** A couple of buffer overruns have been fixed. |
+ |
+** Problems when closing files should now be reported. |
+ |
+** Generated parsers should now work even on operating systems which do |
+ not provide alloca(). |
+ |
+* Changes in version 1.25, 1995-10-16: |
+ |
+** Errors in the input grammar are not fatal; Bison keeps reading |
+the grammar file, and reports all the errors found in it. |
+ |
+** Tokens can now be specified as multiple-character strings: for |
+example, you could use "<=" for a token which looks like <=, instead |
+of chosing a name like LESSEQ. |
+ |
+** The %token_table declaration says to write a table of tokens (names |
+and numbers) into the parser file. The yylex function can use this |
+table to recognize multiple-character string tokens, or for other |
+purposes. |
+ |
+** The %no_lines declaration says not to generate any #line preprocessor |
+directives in the parser file. |
+ |
+** The %raw declaration says to use internal Bison token numbers, not |
+Yacc-compatible token numbers, when token names are defined as macros. |
+ |
+** The --no-parser option produces the parser tables without including |
+the parser engine; a project can now use its own parser engine. |
+The actions go into a separate file called NAME.act, in the form of |
+a switch statement body. |
+ |
+* Changes in version 1.23: |
+ |
+The user can define YYPARSE_PARAM as the name of an argument to be |
+passed into yyparse. The argument should have type void *. It should |
+actually point to an object. Grammar actions can access the variable |
+by casting it to the proper pointer type. |
+ |
+Line numbers in output file corrected. |
+ |
+* Changes in version 1.22: |
+ |
+--help option added. |
+ |
+* Changes in version 1.20: |
+ |
+Output file does not redefine const for C++. |
+ |
+Local Variables: |
+mode: outline |
+End: |
+ |
+----- |
+ |
+Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, |
+2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
+ |
+This file is part of Bison, the GNU Compiler Compiler. |
+ |
+This program is free software: you can redistribute it and/or modify |
+it under the terms of the GNU General Public License as published by |
+the Free Software Foundation, either version 3 of the License, or |
+(at your option) any later version. |
+ |
+This program is distributed in the hope that it will be useful, |
+but WITHOUT ANY WARRANTY; without even the implied warranty of |
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
+GNU General Public License for more details. |
+ |
+You should have received a copy of the GNU General Public License |
+along with this program. If not, see <http://www.gnu.org/licenses/>. |