X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/cdf3f113388c74730337663f7f367f49ffebe12c..cf499cff31eabd04e37107484647bdd453137d1d:/NEWS

diff --git a/NEWS b/NEWS
index bbf25383..ca458c7e 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,33 @@ Bison News
   Also, it is possible to add code to the parser's constructors using
   "%code init" and "%define init_throws".
 
+** Variable api.tokens.prefix
+
+  The variable api.tokens.prefix changes the way tokens are identified in
+  the generated files.  This is especially useful to avoid collisions
+  with identifiers in the target language.  For instance
+
+      %token FILE for ERROR
+      %define api.tokens.prefix "TOK_"
+      %%
+      start: FILE for ERROR;
+
+  will generate the definition of the symbols TOK_FILE, TOK_for, and
+  TOK_ERROR in the generated sources.  In particular, the scanner must
+  use these prefixed token names, although the grammar itself still
+  uses the short names (as in the sample rule given above).
+
+** Variable api.namespace
+
+  The "namespace" variable is renamed "api.namespace".  Backward
+  compatibility is ensured, but upgrading is recommended.
+
+** Variable parse.error
+
+  The variable error controls the verbosity of error messages.  The
+  use of the %error-verbose directive is deprecated in favor of
+  %define parse.error "verbose".
+
 * Changes in version 2.5 (????-??-??):
 
 ** IELR(1) and Canonical LR(1) Support
@@ -28,9 +55,9 @@ Bison News
   default.  You can specify the type of parser tables in the grammar
   file with these directives:
 
-    %define lr.type "LALR"
-    %define lr.type "IELR"
-    %define lr.type "canonical LR"
+    %define lr.type lalr
+    %define lr.type ielr
+    %define lr.type canonical-lr
 
   The default reduction optimization in the parser tables can also be
   adjusted using `%define lr.default-reductions'.  See the documentation
@@ -41,21 +68,30 @@ Bison News
   These features are experimental.  More user feedback will help to
   stabilize them.
 
-** %define can now be invoked via the command line.
+** %define improvements.
+
+*** Multiple invocations for any variable is now an error not a warning.
 
-  Each of these bison command-line options
+*** Can now be invoked via the command line.
 
-    -D NAME=VALUE
-    --define=NAME=VALUE
+  Each of these command-line options
+
+    -D NAME[=VALUE]
+    --define=NAME[=VALUE]
+
+    -F NAME[=VALUE]
+    --force-define=NAME[=VALUE]
 
   is equivalent to this grammar file declaration
 
-    %define NAME "VALUE"
+    %define NAME ["VALUE"]
 
-  for any NAME and VALUE.  Omitting `=VALUE' on the command line is
-  equivalent to omitting `"VALUE"' in the declaration.
+  except that the manner in which Bison processes multiple definitions
+  for the same NAME differs.  Most importantly, -F and --force-define
+  quietly override %define, but -D and --define do not.  For further
+  details, see the section "Bison Options" in the Bison manual.
 
-** %define variables renamed.
+*** Variables renamed.
 
   The following %define variables
 
@@ -70,7 +106,18 @@ Bison News
   The old names are now deprecated but will be maintained indefinitely
   for backward compatibility.
 
-** Symbols names
+*** Values no longer need to be quoted in grammar file.
+
+  If a %define value is an identifier, it no longer needs to be placed
+  within quotations marks.  For example,
+
+    %define api.push-pull "push"
+
+  can be rewritten as
+
+    %define api.push-pull push
+
+** Symbol names.
 
   Consistently with directives (such as %error-verbose) and variables
   (e.g. push-pull), symbol names may include dashes in any position,
@@ -99,8 +146,32 @@ Bison News
   about a missing semicolon where it did not before.  Future releases of
   Bison will cease to append semicolons entirely.
 
+** Character literals not of length one.
+
+  Previously, Bison quietly converted all character literals to length
+  one.  For example, without warning, Bison interpreted the operators in
+  the following grammar to be the same token:
+
+    exp: exp '++'
+       | exp '+' exp
+       ;
+
+  Bison now warns when a character literal is not of length one.  In
+  some future release, Bison will report an error instead.
+
+** Verbose error messages fixed for nonassociative tokens.
+
+  When %error-verbose is specified, syntax error messages produced by
+  the generated parser include the unexpected token as well as a list of
+  expected tokens.  Previously, this list erroneously included tokens
+  that would actually induce a syntax error because conflicts for them
+  were resolved with %nonassoc.  Such tokens are now properly omitted
+  from the list.
+
 * Changes in version 2.4.2 (????-??-??):
 
+** Detection of GNU M4 1.4.6 or newer during configure is improved.
+
 ** %code is now a permanent feature.
 
   A traditional Yacc prologue directive is written in the form: