For associating token numbers with token names for "yacc.c", don't use

#define statements unless `--yacc' is specified; always use enum
yytokentype.  Most important discussions start at:
<http://lists.gnu.org/archive/html/bison-patches/2005-09/msg00053.html>,
<http://lists.gnu.org/archive/html/bison-patches/2005-12/msg00052.html>,
and
<http://lists.gnu.org/archive/html/bison-patches/2006-06/msg00043.html>.
* NEWS (2.3+): Mention.
* data/c.m4 (b4_yacc_if): New.
(b4_token_enums_defines): Use b4_yacc_if to decide whether to add the
token #define's.
* doc/bison.texinfo (Bison Options): Describe the effect of `--yacc'
on token name definitions.
* src/getargs.c (usage): Capitalize `Yacc' in English.
* src/output.c (prepare): Define b4_yacc_flag.
* tests/regression.at (Early token definitions): Test that tokens names
are defined before the pre-prologue not just before the post-prologue.
Remove this test case and copy to...
(Early token definitions with --yacc): ... this to test #define's.
(Early token definitions without --yacc): ... and this to test enums.

NEWS

@@ -3,6 +3,12 @@ Bison News
 
 Changes in version 2.3+:
 
+* 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.
+
 * 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.