(EXTRA_DIST): Avoid +=, a GNU make extension.

[bison.git] / NEWS

diff --git a/NEWS b/NEWS
index 14a42e217e55ed362ef333253f9c47131b37cf16..51836800db71469ff3d051a3747afd1268647961 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,13 +1,26 @@
 Bison News
 ----------
 
 Bison News
 ----------
 

-Changes in version 1.49b:
+Changes in version 1.49b, 2002-08-12:
+
+* 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.
+
+* 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
+  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.
 
 
 * 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.
 

-* Undefined token
+* Unknown token numbers

   If yylex returned a code out of range, yyparse could die.  This is
   no longer the case.
 
   If yylex returned a code out of range, yyparse could die.  This is
   no longer the case.
 


@@ -17,20 +30,48 @@ Changes in version 1.49b:
   user specified that one of her tokens is numbered 256, then error
   will be mapped onto another number.
 
   user specified that one of her tokens is numbered 256, then error
   will be mapped onto another number.
 

-* 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 state 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
+  <http://mail.gnu.org/pipermail/bug-bison/2002-May/001452.html>.
+
+* Traces
+  Popped tokens and nonterminals are now reported.

 
 

-* The initial rule is explicit.
+* 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.
 
   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 are actually removed.
+* Useless rules

   Before, Bison reported the useless rules, but, although not used,
   Before, Bison reported the useless rules, but, although not used,

-  included them in the parsers.
+  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.

 
 

-* False `Token not used' report fixed.
+* Incorrect `Token not used'

   On a grammar such as
 
            %token useless useful
   On a grammar such as
 
            %token useless useful


@@ -40,17 +81,19 @@ Changes in version 1.49b:
   where a token was used to set the precedence of the last rule,
   bison reported both `useful' and `useless' as useless tokens.
 
   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.
+* Revert the C++ namespace changes introduced in 1.31
+  as they caused too many portability hassles.

 
 

-* Items overflow
-  Bison no longer dumps core when there are too many items, it just
-  dies.
+* 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
 
 * 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
   or
   For instance
      %token YYEOF 0
   or


@@ -59,6 +102,41 @@ Changes in version 1.49b:
 * Semantic parser
   This old option, which has been broken for ages, is removed.
 
 * 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'.
+
+* 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.
+
+* 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 <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:
 
 \f
 Changes in version 1.35, 2002-03-25: