X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/09add9c24f4524f4c362cf51a1b555f8c49a6157..478c4a8f495f4b665e6bcb5b5a669089a7bd614a:/NEWS diff --git a/NEWS b/NEWS index 564b087e..490e89ed 100644 --- a/NEWS +++ b/NEWS @@ -2,15 +2,114 @@ GNU Bison NEWS * Noteworthy changes in release ?.? (????-??-??) [?] -** WARNING: Future backward-incompatibilities! +** Bug fixes + +*** Named %union support + + Bison 3.0 introduced a regression on named %union such as + + %union foo { int ival; }; + + The possibility to use a name was introduced ``for Yacc compatibility''. + It is however not required by POSIX Yacc, and its usefulness is not clear. + +*** %define api.value.type union with %defines + + The yacc.c and glr.c parsers were broken when %defines was used + together with "%define api.value.type union". + +*** Redeclarations are reported in proper order + + On + + %token FOO "foo" + %printer {} "foo" + %printer {} FOO + + bison used to report: + + /tmp/foo.yy:2.10-11: error: %printer redeclaration for FOO + %printer {} "foo" + ^^ + /tmp/foo.yy:3.10-11: previous declaration + %printer {} FOO + ^^ + + Now, the "previous" declaration is always the first one. + + +** Documentation + + Bison now installs various files in its docdir (which defaults to + '/usr/local/share/doc/bison'), including the three fully blown examples + extracted from the documentation: + + - rpcalc + Reverse polish calculator, a simple introductory example. + - mfcalc + Multi-function Calc, a calculator with memory and functions and located + error messages. + - calc++ + a calculator in C++ using variant support and token constructors. + +* Noteworthy changes in release 3.0.2 (2013-12-05) [stable] + +** Bug fixes + +*** Generated source files when errors are reported + + When warnings are issued and -Werror is set, bison would still generate + the source files (*.c, *.h...). As a consequence, some runs of "make" + could fail the first time, but not the second (as the files were generated + anyway). + + This is fixed: bison no longer generates this source files, but, of + course, still produces the various reports (*.output, *.xml, etc.). - Bison will stop adding a semicolon at the end of the actions (as announced - in the release 2.5): +*** %empty is used in reports - foo.y:2.22: warning: a ';' might be needed at the end of action code - exp: "num" { $$ = $1 } - ^ - foo.y:2.22: future versions of Bison will not add the ';' + Empty right-hand sides are denoted by '%empty' in all the reports (text, + dot, XML and formats derived from it). + +*** YYERROR and variants + + When C++ variant support is enabled, an error triggered via YYERROR, but + not caught via error recovery, resulted in a double deletion. + +* Noteworthy changes in release 3.0.1 (2013-11-12) [stable] + +** Bug fixes + +*** Errors in caret diagnostics + + On some platforms, some errors could result in endless diagnostics. + +*** Fixes of the -Werror option + + Options such as "-Werror -Wno-error=foo" were still turning "foo" + diagnostics into errors instead of warnings. This is fixed. + + Actually, for consistency with GCC, "-Wno-error=foo -Werror" now also + leaves "foo" diagnostics as warnings. Similarly, with "-Werror=foo + -Wno-error", "foo" diagnostics are now errors. + +*** GLR Predicates + + As demonstrated in the documentation, one can now leave spaces between + "%?" and its "{". + +*** Installation + + The yacc.1 man page is no longer installed if --disable-yacc was + specified. + +*** Fixes in the test suite + + Bugs and portability issues. + +* Noteworthy changes in release 3.0 (2013-07-25) [stable] + +** WARNING: Future backward-incompatibilities! Like other GNU packages, Bison will start using some of the C99 features for its own code, especially the definition of variables after statements. @@ -28,6 +127,29 @@ GNU Bison NEWS Support for YYLEX_PARAM and YYPARSE_PARAM is removed (deprecated in Bison 1.875): use %lex-param, %parse-param, or %param. + Missing semicolons at the end of actions are no longer added (as announced + in the release 2.5). + +*** Use of YACC='bison -y' + + TL;DR: With Autoconf <= 2.69, pass -Wno-yacc to (AM_)YFLAGS if you use + Bison extensions. + + Traditional Yacc generates 'y.tab.c' whatever the name of the input file. + Therefore Makefiles written for Yacc expect 'y.tab.c' (and possibly + 'y.tab.h' and 'y.outout') to be generated from 'foo.y'. + + To this end, for ages, AC_PROG_YACC, Autoconf's macro to look for an + implementation of Yacc, was using Bison as 'bison -y'. While it does + ensure compatible output file names, it also enables warnings for + incompatibilities with POSIX Yacc. In other words, 'bison -y' triggers + warnings for Bison extensions. + + Autoconf 2.70+ fixes this incompatibility by using YACC='bison -o y.tab.c' + (which also generates 'y.tab.h' and 'y.output' when needed). + Alternatively, disable Yacc warnings by passing '-Wno-yacc' to your Yacc + flags (YFLAGS, or AM_YFLAGS with Automake). + ** Bug fixes *** The epilogue is no longer affected by internal #defines (glr.c) @@ -39,7 +161,7 @@ GNU Bison NEWS int yylex (YYSTYPE *yylval); - This is has been fixed: yylval, yynerrs, yychar, and yylloc are now valid + This is fixed: yylval, yynerrs, yychar, and yylloc are now valid identifiers for user-provided variables. *** stdio.h is no longer needed when locations are enabled (yacc.c) @@ -47,6 +169,8 @@ GNU Bison NEWS Changes in Bison 2.7 introduced a dependency on FILE and fprintf when locations are enabled. This is fixed. +*** Warnings about useless %pure-parser/%define api.pure are restored + ** Diagnostics reported by Bison Most of these features were contributed by Théophile Ranquet and Victor @@ -221,6 +345,11 @@ GNU Bison NEWS bar.y: error: shift/reduce conflicts: 1 found, 0 expected bar.y: error: reduce/reduce conflicts: 2 found, 0 expected +** Incompatibilities with POSIX Yacc + + The 'yacc' category is no longer part of '-Wall', enable it explicitly + with '-Wyacc'. + ** Additional yylex/yyparse arguments The new directive %param declares additional arguments to both yylex and @@ -236,6 +365,23 @@ GNU Bison NEWS %param {arg1_type *arg1} {arg2_type *arg2} +** Types of values for %define variables + + Bison used to make no difference between '%define foo bar' and '%define + foo "bar"'. The former is now called a 'keyword value', and the latter a + 'string value'. A third kind was added: 'code values', such as '%define + foo {bar}'. + + Keyword variables are used for fixed value sets, e.g., + + %define lr.type lalr + + Code variables are used for value in the target language, e.g., + + %define api.value.type {struct semantic_type} + + String variables are used remaining cases, e.g. file names. + ** Variable api.token.prefix The variable api.token.prefix changes the way tokens are identified in @@ -243,7 +389,7 @@ GNU Bison NEWS with identifiers in the target language. For instance %token FILE for ERROR - %define api.token.prefix "TOK_" + %define api.token.prefix {TOK_} %% start: FILE for ERROR; @@ -252,6 +398,79 @@ GNU Bison NEWS use these prefixed token names, although the grammar itself still uses the short names (as in the sample rule given above). +** Variable api.value.type + + This new %define variable supersedes the #define macro YYSTYPE. The use + of YYSTYPE is discouraged. In particular, #defining YYSTYPE *and* either + using %union or %defining api.value.type results in undefined behavior. + + Either define api.value.type, or use "%union": + + %union + { + int ival; + char *sval; + } + %token INT "integer" + %token STRING "string" + %printer { fprintf (yyo, "%d", $$); } + %destructor { free ($$); } + + /* In yylex(). */ + yylval.ival = 42; return INT; + yylval.sval = "42"; return STRING; + + The %define variable api.value.type supports both keyword and code values. + + The keyword value 'union' means that the user provides genuine types, not + union member names such as "ival" and "sval" above (WARNING: will fail if + -y/--yacc/%yacc is enabled). + + %define api.value.type union + %token INT "integer" + %token STRING "string" + %printer { fprintf (yyo, "%d", $$); } + %destructor { free ($$); } + + /* In yylex(). */ + yylval.INT = 42; return INT; + yylval.STRING = "42"; return STRING; + + The keyword value variant is somewhat equivalent, but for C++ special + provision is made to allow classes to be used (more about this below). + + %define api.value.type variant + %token INT "integer" + %token STRING "string" + + Code values (in braces) denote user defined types. This is where YYSTYPE + used to be used. + + %code requires + { + struct my_value + { + enum + { + is_int, is_string + } kind; + union + { + int ival; + char *sval; + } u; + }; + } + %define api.value.type {struct my_value} + %token INT "integer" + %token STRING "string" + %printer { fprintf (yyo, "%d", $$); } + %destructor { free ($$); } + + /* In yylex(). */ + yylval.u.ival = 42; return INT; + yylval.u.sval = "42"; return STRING; + ** Variable parse.error This variable controls the verbosity of error messages. The use of the @@ -284,17 +503,33 @@ GNU Bison NEWS It used to be an error only if used in non GLR mode, _and_ if there are reduce/reduce conflicts. -** Token numbering has changed to preserve the user-defined order +** Tokens are numbered in their order of appearance + + Contributed by Valentin Tolmer. + + With '%token A B', A had a number less than the one of B. However, + precedence declarations used to generate a reversed order. This is now + fixed, and introducing tokens with any of %token, %left, %right, + %precedence, or %nonassoc yields the same result. + + When mixing declarations of tokens with a litteral character (e.g., 'a') + or with an identifier (e.g., B) in a precedence declaration, Bison + numbered the litteral characters first. For example - When declaring %token A B, the numbering for A is inferior to B. Up to now, - when declaring associativity at the same time, with %left (or %right, - %precedence, %nonassoc), B was inferior to A. + %right A B 'c' 'd' + + would lead to the tokens declared in this order: 'c' 'd' A B. Again, the + input order is now preserved. + + These changes were made so that one can remove useless precedence and + associativity declarations (i.e., map %nonassoc, %left or %right to + %precedence, or to %token) and get exactly the same output. ** Useless precedence and associativity Contributed by Valentin Tolmer. - When developping and maintaining a grammar, useless associativity and + When developing and maintaining a grammar, useless associativity and precedence directives are common. They can be a nuisance: new ambiguities arising are sometimes masked because their conflicts are resolved due to the extra precedence or associativity information. Furthermore, it can @@ -319,8 +554,8 @@ GNU Bison NEWS %left '*' %% exp: - "num" - | exp '+' "num" + "number" + | exp '+' "number" | exp '*' exp ; @@ -339,7 +574,7 @@ GNU Bison NEWS %precedence '=' %% - exp: "var" '=' "num"; + exp: "var" '=' "number"; will produce a @@ -354,7 +589,7 @@ GNU Bison NEWS %nonassoc '=' %% - exp: "var" '=' "num"; + exp: "var" '=' "number"; The warning is: @@ -364,6 +599,8 @@ GNU Bison NEWS ** Empty rules + With help from Joel E. Denny and Gabriel Rassoul. + Empty rules (i.e., with an empty right-hand side) can now be explicitly marked by the new %empty directive. Using %empty on a non-empty rule is an error. The new -Wempty-rule warning reports empty rules without @@ -386,11 +623,13 @@ GNU Bison NEWS ** Java skeleton improvements - Contributed by Paolo Bonzini. - 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". + Contributed by Paolo Bonzini. + + The Java skeleton now supports push parsing. + Contributed by Dennis Heimbigner. ** C++ skeletons improvements @@ -432,7 +671,7 @@ GNU Bison NEWS ; list: - /* nothing */ { /* Generates an empty string list */ } + %empty { /* Generates an empty string list. */ } | list item ";" { std::swap ($$, $1); $$.push_back ($2); } ; @@ -459,6 +698,21 @@ GNU Bison NEWS ... } +*** C++ locations + + There are operator- and operator-= for 'location'. Negative line/column + increments can no longer underflow the resulting value. + +* Noteworthy changes in release 2.7.1 (2013-04-15) [stable] + +** Bug fixes + +*** Fix compiler attribute portability (yacc.c) + + With locations enabled, __attribute__ was used unprotected. + +*** Fix some compiler warnings (lalr1.cc) + * Noteworthy changes in release 2.7 (2012-12-12) [stable] ** Bug fixes @@ -509,8 +763,8 @@ GNU Bison NEWS exp: exp '+' exp { $exp = $1 + $3; }; ^^^ - The default behaviour for now is still not to display these unless - explictly asked with -fcaret (or -fall). However, in a later release, it + The default behavior for now is still not to display these unless + explicitly asked with -fcaret (or -fall). However, in a later release, it will be made the default behavior (but may still be deactivated with -fno-caret). @@ -597,7 +851,7 @@ GNU Bison NEWS Other issues in the test suite have been addressed. - Nul characters are correctly displayed in error messages. + Null characters are correctly displayed in error messages. When possible, yylloc is correctly initialized before calling yylex. It is no longer necessary to initialize it in the %initial-action. @@ -2478,7 +2732,7 @@ Output file does not redefine const for C++. ----- -Copyright (C) 1995-2013 Free Software Foundation, Inc. +Copyright (C) 1995-2015 Free Software Foundation, Inc. This file is part of Bison, the GNU Parser Generator. @@ -2513,7 +2767,12 @@ along with this program. If not, see . LocalWords: Automake TMPDIR LESSEQ ylwrap endif yydebug YYTOKEN YYLSP ival hh LocalWords: extern YYTOKENTYPE TOKENTYPE yytokentype tokentype STYPE lval pdf LocalWords: lang yyoutput dvi html ps POSIX lvalp llocp Wother nterm arg init - LocalWords: TOK calc yyo fval Wconflicts + LocalWords: TOK calc yyo fval Wconflicts parsers yystackp yyval yynerrs + LocalWords: Théophile Ranquet Santet fno fnone stype associativity Tolmer + LocalWords: Wprecedence Rassoul Wempty Paolo Bonzini parser's Michiel loc + LocalWords: redeclaration sval fcaret reentrant XSLT xsl Wmaybe yyvsp Tedi + LocalWords: pragmas noreturn untyped Rozenman unexpanded Wojciech Polak + LocalWords: Alexandre MERCHANTABILITY yytype Local Variables: mode: outline