Give a try to M4 as a back end.

* lib/readpipe.c: New, from wdiff.
* src/Makefile.am (DEFS): Define PKGDATADIR, not BISON_SIMPLE and
BISON_HAIRY.
* src/system.h (BISON_HAIRY, BISON_SIMPLE): Remove the DOS and VMS
specific values.  Now it is m4 that performs the lookup.
* src/parse-skel.y: Remove.
* src/muscle_tab.c, src/muscle_tab.h (muscles_m4_output): New.
* src/output.c (actions_output, guards_output)
(token_definitions_output): No longer keeps track of the output
line number, hence remove the second argument.
(guards_output): Check against the guard member of a rule, not the
action member.
Adjust callers.
(output_skeleton): Don't look for the skeleton location, let m4 do
that.
Create `/tmp/muscles.m4'.  This is temporary, a proper temporary
file will be used.
Invoke `m4' on m4sugar.m4, muscles.m4, and the skeleton.
(prepare): Given that for the time being changesyntax is not
usable in M4, rename the muscles using `-' to `_'.
Define `defines_flag', `output_parser_name' and `output_header_name'.
* src/output.h (actions_output, guards_output)
(token_definitions_output): Adjust prototypes.
* src/scan-skel.l: Instead of scanning the skeletons, it now
processes the output of m4: `__oline__' and `#output'.
* data/bison.simple: Adjust to be used by M4(sugar).
* tests/Makefile.am: Use check_SCRIPTS to make sure `bison' is up
to date.
* tests/bison.in: Use the secrete envvar `BISON_PKGDATADIR'
instead of the dead `BISON_SIMPLE' and `BISON_HAIRY'.
* data/m4sugar/m4sugar.m4, data/m4sugar/version.m4: New,
shamelessly stolen from CVS Autoconf.

src/Makefile.am

@@ -1,4 +1,4 @@
-## Copyright 2001 Free Software Foundation, Inc.
+## Copyright (C) 2001, 2002 Free Software Foundation, Inc.
 
 ## 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
@@ -18,8 +18,7 @@
 AUTOMAKE_OPTIONS = ../lib/ansi2knr
 
 DEFS = @DEFS@ \
-  -DBISON_SIMPLE=\"$(pkgdatadir)/bison.simple\" \
-  -DBISON_HAIRY=\"$(pkgdatadir)/bison.hairy\" \
+  -DPKGDATADIR=\"$(pkgdatadir)\" \
   -DLOCALEDIR=\"$(datadir)/locale\"
 
 CFLAGS = @CFLAGS@ $(WARNING_CFLAGS) $(WERROR_CFLAGS)
@@ -45,9 +44,9 @@ bison_SOURCES = LR0.c closure.c complain.c conflicts.c	\
     muscle_tab.h muscle_tab.c \
     options.h options.c \
     print.c reader.c reduce.c symtab.c warshall.c vcg.c \
-    skeleton.h parse-skel.h parse-skel.y scan-skel.l
+    scan-skel.l
 
-BUILT_SOURCES = parse-skel.c scan-skel.c
+BUILT_SOURCES = scan-skel.c
 
 EXTRA_bison_SOURCES = vmsgetargs.c